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Molecular and Cellular Biology, October 2000, p. 7773-7783, Vol. 20, No. 20
0270-7306/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Meiotic Telomere Distribution and Sertoli Cell Nuclear
Architecture Are Altered in Atm- and
Atm-p53-Deficient Mice
Harry
Scherthan,1
Martin
Jerratsch,1
Sonu
Dhar,2
Y. Alan
Wang,3
Stephen P.
Goff,2 and
Tej K.
Pandita2,*
University of Kaiserslautern, D-67653
Kaiserslautern, Germany1; Columbia
University, New York, New York 100322; and
Harvard Medical School, Boston, Massachusetts3
Received 31 January 2000/Returned for modification 20 June
2000/Accepted 18 July 2000
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ABSTRACT |
The ataxia telangiectasia mutant (ATM) protein is an intrinsic part
of the cell cycle machinery that surveys genomic integrity and
responses to genotoxic insult. Individuals with ataxia telangiectasia as well as Atm
/ mice are predisposed to
cancer and are infertile due to spermatogenesis disruption during first
meiotic prophase. Atm/
spermatocytes frequently display aberrant synapsis and clustered telomeres (bouquet topology). Here, we used telomere fluorescent in
situ hybridization and immunofluorescence (IF) staining of SCP3 and
testes-specific histone H1 (H1t) to spermatocytes of Atm-
and Atm-p53-deficient mice and investigated whether gonadal atrophy in Atm-null mice is associated with stalling of
telomere motility in meiotic prophase. SCP3-H1t IF revealed that most
Atm/ p53/ spermatocytes
degenerated during late zygotene, while a few progressed to
pachytene and diplotene and some even beyond metaphase II, as indicated
by the presence of a few round spermatids. In
Atm/ p53/ meiosis, the
frequency of spermatocytes I with bouquet topology was elevated
72-fold. Bouquet spermatocytes with clustered telomeres were generally
void of H1t signals, while mid-late pachytene and diplotene
Atm/ p53/ spermatocytes
displayed expression of H1t and showed telomeres dispersed over
the nuclear periphery. Thus, it appears that meiotic telomere movements
occur independently of ATM signaling. Atm inactivation more
likely leads to accumulation of spermatocytes I with bouquet topology by slowing progression through initial stages of first meiotic
prophase and an ensuing arrest and demise of spermatocytes I. Sertoli
cells (SECs), which contribute to faithful spermatogenesis, in the
Atm mutants were found to frequently display numerous
heterochromatin and telomere clusters
a nuclear topology which
resembles that of immature SECs. However,
Atm/ SECs exhibited a mature vimentin and
cytokeratin 8 intermediate filament expression signature. Upon IF with
ATM antibodies, we observed ATM signals throughout the nuclei
of human and mouse SECs, spermatocytes I, and haploid round spermatids.
ATM but not H1t was absent from elongating spermatid nuclei. Thus, ATM
appears to be removed from spermatid nuclei prior to the occurrence of DNA nicks which emanate as a consequence of nucleoprotamine formation.
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INTRODUCTION |
Ataxia telangiectasia is a rare
human recessive autosomal disorder with a pleiotropic phenotype,
specifically including progressive neurological degeneration,
telangiectasia, often associated with premature aging, reduced size,
immunodeficiency, sensitivity to ionizing radiation, cancer
predisposition, and infertility (13, 40, 81, 93). Mice
mutated in the homologue of the ATM (ataxia telangiectasia
mutated) gene (Atm) display similar pleiotropic defects
(5, 27, 97). The ATM protein belongs to a growing family of
phosphatidylinositol-3 kinase-related kinases and seems to play a role
as an intrinsic part of the cell cycle machinery that surveys genomic
integrity, cell cycle progression, and processing of DNA damage. It
shows similarity to several yeast and mammalian proteins involved in
meiotic recombination and cell cycle progression, namely, the products
of MEC1 in the budding yeast Saccharomyces cerevisiae and rad3+ of the fission yeast
Schizosaccharomyces pombe (9, 56) and the TOR
proteins of yeasts and mammals (45, 75). Besides its role in
the mitotic cell cycle and development (14, 53, 98), the ATM
protein and its relative ATR (ATM and rad3 related) have been regarded
as important components in the machinery monitoring progression of
meiotic recombination, double-strand break repair, and homologue
pairing (60, 69), which is in agreement with the location of
Atm throughout meiotic chromatin (7, 28). Detection and
signaling of DNA damage are possibly mediated through downstream
targets of ATM like c-Abl, Chk1, Chk2, and Rad51 proteins (8, 17,
19, 26). Furthermore, MEC1, the yeast homologue of the ATM
phosphatidylinositol-3 kinase, is known to exert checkpoint function in
the mitotic and meiotic cell cycle, and its absence mediates a defect
in synapsis (35, 56). MEC1 is required for phosphorylation
of replication protein A (Rpa) as a response to radiation-induced DNA
damage (15). Rpa has been shown to interact with Rad51
(36), which plays an important role in meiotic recombination (82, 83, 89) and localizes to meiotic recombination
complexes (1, 89, 90). Consistent with a role for ATM in
meiosis, individuals with ataxia telangiectasia display gonadal atrophy and spermatogenetic failure, a phenotype which is mirrored by Atm-deficient mice (5, 97).
Cell lines derived from ataxia telangiectasia patients are
hypersensitive to ionizing radiation (53, 58, 88) and
display a prominent chromatin defect at chromosome ends in the form of chromosome end-to-end associations or telomeric associations seen at
metaphase (49, 63, 64). Telomere associations correlate with
genomic instability and carcinogenicity (21, 64, 65). Telomeres contain both DNA and protein that concertedly stabilize the
ends of eukaryotic DNA, thereby protecting chromosome ends from
exonucleolytic attack, fusion, and degradation (for reviews, see
references 11 and 99). In the
mammalian interphase nucleus, telomeres appear to be attached to the
filamentous nuclear matrix (55), while in budding yeast
cells, telomeres are clustered in a few perinuclear chromatin domains
(20). Because of the ATM homology to
Mec1/Tel1 of S. cerevisiae (34, 74),
it has been suggested that mutations in ATM could lead to
altered telomere metabolism. We have recently reported alterations in
both basal and radiation-induced telomeric associations and in mean
telomere length in isogenic cells with manipulated ATM, demonstrating a direct link between ATM function and telomere maintenance
(84). Furthermore, it was shown that ATM
disruption leads to a telomeric chromatin defect in that telomere
repeats are predominantly enriched in the insoluble nuclear matrix
fraction (65, 85). Atm/
spermatocytes I also have their telomeric repeats enriched in the
nuclear matrix fraction and display an altered distribution of
chromosome ends in the meiotic prophase nucleus, i.e.,
numerous nuclei have telomeres accumulated at a limited sector of the
nuclear envelope (65)a nuclear topology which resembles a
chromosomal bouquet, which is usually seen at the leptotene-zygotene
transition during meiotic prophase of the mouse (79) and
other species (22, 100). Bouquet formation appears to be a
consistent motif of meiotic prophase of the vast majority if not all
eukaryotic species (for a review, see reference 23)
and is thought to instigate interactions along aligned and spatially
accumulated chromosome end segments. In this way it may bring about
prealignment and facilitate the sorting process of homologues prior to
their synaptic pairing (22, 54, 72, 91).
Spermatogenesis in male Atm/ mice is
disrupted during earliest prophase I, leading to chromosome
fragmentation and spermatocyte degeneration during zygotene (5,
97). Aberrant zygotene-equivalent spermatocytes I of
Atm-deficient mice frequently display a nuclear architecture
of bouquet cells (65), which poses the question whether
Atm inactivation stalls meiotic telomere movements at the
cluster site. Here, we investigate telomere distribution in spermatocytes I of Atm-p53 double-knockout mice, which show
a partial rescue of progression through the first meiotic prophase (6). In this double mutant we observed a dramatic increase in the frequency of spermatocytes I with bouquet topology and show that
a small number of mid-late pachytene and diplotene spermatocytes, as
identified by the expression of the testis-specific histone H1 (H1t)
and the synaptonemal complex protein SCP3, have telomeres dispersed
over the nuclear periphery. Furthermore, it is shown that
Atm disruption causes an immature nuclear architecture and heterochromatin distribution in Sertoli cells (SECs), the supportive somatic cell lineage of the seminiferous epithelium; they were found to
display strong immunofluorescence (IF) Atm signals in their chromatin.
Atm was detected in the chromatin of human SECs, mouse and human
spermatocytes I, and developing spermatids.
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MATERIALS AND METHODS |
Mice and tissues.
For the present study, we used mice that
are deficient for Atm, p53, and c-Abl
and double null for Atm and p53. The mating pairs
for Atm heterozygotes were obtained from Philip Leder,
Harvard Medical School, Boston. p53+/ mating
mice were obtained from Larry Donehower, Baylor College of Medicine,
Houston, Tex. The genotyping of the Atm+/,
p53+/, and Atm+/
p53+/ mice was done by the procedure described by
Westphal et al. (94), and the genotyping of c-Abl
null mice was done according to the protocol of Hardin et al.
(39). The alleles are carried on mixed genetic background
mice (129SvEv × Black Swiss). Animal colonies were maintained at
the animal care facility of Columbia University College of Physicians
and Surgeons, New York. Generally, mice of 42 days of age were
sacrificed, and testes were resected for further processing or instant
snap freezing in liquid N2. Frozen testicles were kept at
70°C until further use. Control IF experiments were also carried
out on human testis biopsy material (79) which had been
stored in liquid nitrogen.
Chromosome preparations, cell suspensions, and tissue
sections.
To obtain structurally preserved nuclei for
three-dimensional analysis, male mice were killed by cervical
dislocation. Testes were removed, and structurally preserved suspension
nuclei were prepared by cross-linking fixation with phosphate-buffered
saline (PBS)-buffered formaldehyde (65) and using the
following modifications. Testicular fragments were minced with scalpels
in cold minimal essential medium containing protease inhibitor (Roche
Biochemicals). This suspension was mixed in equal volumes with fixative
(3.7% formaldehyde, 0.1 M sucrose [pH 7.2]) and placed on
silane-coated glass slides (Menzel Gläser). After air drying and
prior to IF staining, the resulting sucrose coating was removed by
rinsing the preparations repeatedly in PBS.
FISH.
For fluorescence in situ hybridization, a directly
labeled (TTAGGG)3 PNA probe was used to detect
telomere repeats (telo-FISH). When telo-FISH was combined with IF, we
first performed immunostaining and then subjected preparations to
simultaneous denaturation in the presence of the telomere probe
(79). To mark the centromere-kinetochore region in SECs, we
designed a 42-mer oligonucleotide (MiS1; 5'-GTGTA TATCA
TAGAG TTACA ATGAG AAACA TGGAA AA-3'), which is homologous to
the minor satellite of Mus musculus (95) and
localizes to the kinetochore region of mouse metaphase chromosomes (see
inset in Fig. 7e and not shown). Localization of minor satellite DNA to
kinetochore regions of all M. musculus chromosomes has been reported previously (95). Labeling, FISH, and detection of
oligonucleotides were performed as described (78).
Antisera.
A polyclonal rabbit anti-SCP3 antiserum was
utilized to detect axial cores and complete synaptonemal complexes
(SCs) (52). A rabbit antiserum against testis-specific
histone H1 (H1t) was used as previously described (59). An
anti-cytokeratin 8 monoclonal antibody (MAb; clone 35
H11; Dako) and
a goat antivimentin antiserum (31) were used to stain for
SEC-specific intermediate filaments (3).
Two Abs to ATM were commercially obtained. Affinity-purified rabbit
antiserum Ab1 (NB100-104) raised against an ATM fragment containing
amino acids 2138 to 2739 expressed in Escherichia coli (27) was obtained from Novus Biologicals. An
affinity-purified MAb to ATM, which was raised against a glutathione
S-transferase fusion protein corresponding to amino acids
2577 to 3056 (2C1), was obtained from GeneTex, and its specificity in
immunocytology and Western blots has been demonstrated earlier (7,
18). We tested the specificity of the Abs in mouse and human
testis suspensions and performed IF analysis with the 2C1 MAb
(18), since it produced a dispersed granular staining in
both mouse and human testis suspension nuclei. Ab1 (Novus) was found to
produce the same pattern of labeling in spermatocyte nuclei of both
species, but in the mouse it additionally created strong granular IF
signals throughout the sex vesicle (unpublished observations).
Immunostaining.
IF staining of the SC lateral element SCP3
protein was done as described previously (65) with some
modifications. Briefly, sucrose-embedded cells were washed with PBS,
extracted for 30 min with 0.5% Triton X-100-PBS, and incubated with
rabbit anti-SCP3 polyclonal serum diluted 1:1,000 in PTBG (PBS with
0.1% Tween 20, 0.2% bovine serum albumin, and 0.1% gelatin)
overnight at 4°C. Cells were washed three times for 5 min each with
PTBG and incubated with a secondary fluorescein isothiocyanate
(FITC)-conjugated sheep anti-rabbit immunoglobulin (Ig) antibody
(Sigma; diluted 1:250 in PTBG). After three washes in PBS-Tween 20 for
3 min each, preparations were mounted in antifade solution (Vector
Laboratories) containing DAPI (4',6'-diamidino-2-phenylindole; Sigma)
(0.1 µg/ml) as DNA counterstain. For subsequent in situ
hybridization, preparations obtained by this procedure were fixed for 5 min in PBS-0.1% formaldehyde (acid free; Merck), rinsed in PBS-0.1%
glycine to quench aldehyde groups, and subjected to FISH (see above).
Immunostaining with Abs to cytokeratin 8 (MAb 35
H11; Dako) and
vimentin (
31) was done as described above. Vimentin was
detected with secondary tetramethyl rhodamine isocyanate
(TRITC)-conjugated
anti-goat Ig Abs (Sigma; diluted 1:500 in
PBS-Tween), while cytokeratin
8 was detected using secondary anti-mouse
Ig-FITC Abs (Jackson
Labs). Cytokeratin and vimentin immunoreactivity
was verified
on cytospin preparations of HeLa cells (not shown), which
express
both intermediate filament markers (
61). Abs to ATM
(diluted
1:100 in PTBG) were reacted with testis preparations as
described
above. Primary Abs were incubated with a biotinylated
secondary
Ab (Sigma; diluted 1:500 in PTBG), which was then visualized
with
ExtrAvidin-FITC (Sigma; diluted 1:500 in PTBG). Both Abs produced
labeling throughout nuclear chromatin of testis suspension cells.
The
specificity of this chromatin-like labeling was verified by
the absence
of nuclear signals in
Atm/ testes nuclei or
in reactions without the primary Abs (not
shown).
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RESULTS |
Here, we investigate whether the aberrant meiotic telomere
distribution caused by the Atm mutation (65) is
retained in advanced spermatocytes of Atm p53
double-knockout mice. Unlike in the Atm single mutant,
spermatogenesis in the double mutant proceeds beyond the
leptotene-zygotene transition although fertility is not restored (6). For further comparison, we also monitored
spermatogenesis in mice deficient for genes which act downstream of
Atm, namely p53 and c-Abl (8, 43,
80).
To determine and verify the impact of the mutations studied on
spermatogenesis, progression of meiotic prophase was monitored by IF of
SCP3 lateral element proteins (44, 76) of the SC in spread
spermatocytes I of the various homozygous deletion mice (not shown)
(65). In agreement with previous investigations (6, 7,
65, 97), our analysis revealed a meiotic prophase arrest in
Atm/ and Atm/
p53/ mice which manifested in a high frequency of
aberrant spermatocytes showing defects in all aspects of SC formation,
i.e., fragmented SCs, pairing-partner switches, absence of sex vesicle
formation, and unpaired axial cores (not shown). Furthermore, we
detected few late pachytene and diplotene cells as well as a few
spermatids in Atm/ p53/
testis preparations (see below), which extends earlier observations according to which some Atm/
p53/ spermatocytes I reach the pachytene stage
(6). Control, c-Abl/ and
p53/ mice, in contrast, showed normal
progression through male meiotic prophase (not shown). The fairly
normal progression of early prophase I observed in the
c-Abl/ mice used in this investigation would
be consistent with a role of c-Abl signaling in haploid
spermatids (26, 70) and a variable phenotype according to
which the majority of but not all c-Abl/
mice exhibit defects in gametogenesis (50, 92). It is not known at present whether the action of the c-Abl-related
tyrosine kinase Arg (50) is responsible for the variations
in fertility in our c-Abl knockout mice.
Atm/ p53/ disruption
causes a pronounced accumulation of spermatocytes with clustered
telomeres.
Atm disruption has been shown to increase the
level of spermatocyte nuclei with locally clustered telomeres (bouquet
arrangement) (65). To investigate whether this feature is
also present in Atm/ p53/
spermatocytes I, we prepared testicular suspensions by cross-linking fixation with formaldehyde, which maintains nuclear topology to a
considerable degree (65), and hybridized these in situ with a telomere repeat PNA probe (Fig. 1).
When we assessed the frequency of nuclei with clustered telomeres in
Atm/ spermatocytes, a 32-fold increase over
wild-type frequencies (0.12%) was noted (Table
1). Investigation of nuclear suspensions of Atm/ p53/ testicles
revealed a further twofold increase in the frequency of spermatocytes
with a bouquet topology compared to frequencies of
Atm/ testes, or, in other words, a 72-fold
increase in bouquet cells over the control (Table 1).
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FIG. 1.
PNA telo-FISH to testis suspension nuclei of
Atm-p53-deficient mice. (a and b) Telomeres (whitish) are
scattered throughout premeiotic, somatic nuclei (gray), as seen at the
maximum nuclear diameter. (c and d) Top view of spermatocyte I nuclei
which display telomeres clustered at a limited sector of the nuclear
periphery (indicative of leptotene-zygotene transition). DNA was
counterstained with DAPI (gray).
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Telomere clustering is relaxed in Atm/
p53/ mid-late pachytene spermatocytes.
To
address the question whether accumulation of bouquet spermatocytes
results from immobilization of leptotene-zygotene telomeres, which are
aberrantly associated with the nuclear matrix (65, 85), or
whether the former effect is simply the consequence of prophase I
arrest during zygotene, we assessed the topology of telomere
distribution in Atm/ and
Atm/ p53/ spermatocytes.
Advanced spermatocytes I can be identified by IF staining of
testis-specific H1t and SCP3. H1t appears in mid-pachynema and is
present until haploid spermatids reach the elongation stage (25,
59). Consistent with previous observations (59), H1t and SCP3 costaining revealed H1t fluorescence in the chromatin of
undisrupted spermatocytes post-mid-pachytene and during diplotene as
well as in round and elongated spermatids of wild-type mice (not
shown). In Atm/ testis suspensions, however,
only one of several hundred spermatocytes investigated showed distinct
H1t immunofluorescence and displayed characteristics of mid-pachytene
SC formation, with strong labeling of partially polarized SCs having
thickened ends (Fig. 2). Diplotene spermatocytes and haploid spermatids were absent in
Atm/ testis suspensions, which corroborates
earlier findings showing that the vast majority of spermatocytes I get
eliminated at the leptotene-zygotene transition (5, 7, 97).
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FIG. 2.
Histone H1t (red) and anti-SCP3 (green) immunostaining
to Atm/ testis nuclei. (a) An aberrant
spermatocyte I shows axial cores and fragments of SCs near a large
chromocenter (bright blue). (b) Spermatocyte nucleus at zygotene
equivalent stage with fragments of SCs is devoid of H1t signals. The
SEC nucleus below (arrowhead) displays a large nucleolus (dark area
void of H1t signal) and distinct dispersed H1t signals throughout its
chromatin. Note that H1t signals were not seen in wild-type SECs (not
shown). (c) A rare late-pachytene spermatocyte nucleus exhibiting H1t
fluorescence and strongly labeled SCs with thickened ends. DNA is
counterstained with DAPI (blue).
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H1t and SCP3 IF costaining of
Atm/
p53/ testis suspensions disclosed the presence of
mid-late pachytene spermatocytes (Fig.
3), which agrees with previous data
(
57,
59). In our mice
we furthermore detected diplotene
spermatocytes as well as round
and elongated haploid spermatids (Fig.
3e and f and 4d to f).
If stalling of
meiotic telomere movements relates to
Atm deficiency,
one
would expect H1t-positive late pachytene and diplotene
Atm/ p53/ spermatocytes to
be endowed with a bouquet topology. To test
this possibility, we
determined the mode of telomere distribution
in
Atm-p53-deficient spermatocytes by H1t IF and telo-FISH.
Interestingly,
it was found that chromosome ends were generally
dispersed over
the nuclear periphery of
Atm/ p53/ post-mid-pachytene
and diplotene spermatocytes (Fig.
4c to e).
Thus, it appears that
chromosome polarization is resolved during
pachytene of
Atm/ p53/ spermatocytes and
that the absence of functional ATM does not
stall meiotic telomere
movements.
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FIG. 3.
H1t (red) and anti-SCP3 (green) immunostaining of
Atm/ p53/ meiocytes. (a)
Leptotene spermatocyte with faintly stained fragments of axial
elements. (b) Zygotene nucleus with long axial elements and stronger
SCP3 signal spots, which indicate some SC formation. (c) Aberrant
spermatocyte I with fragmented SCs. Absence of H1t fluorescence
indicates that this spermatocyte has not reached mid-pachytene. (d)
Late-pachytene spermatocyte (arrowhead) with H1t-positive chromatin
(red). (e) Diplotene spermatocyte with faintly labeled axial cores
embedded in H1t-positive chromatin. (f) Nucleus of a round spermatid
with a single DAPI-bright chromocenter and H1t-positive chromatin. DNA
was stained with DAPI.
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FIG. 4.
Combined telo-FISH (FITC, green) and H1t immunostaining
(Cy3, red) to suspension nuclei of Atm/
p53/ testis. (a) Premeiotic nucleus, which
exhibits telomere signals (green) dispersed throughout the nuclear
lumen, as seen at the focal plane at the nuclear center. (b) Top view
of the nucleus of a bouquet spermatocyte discloses clustered telomeres
at a limited sector of the nuclear periphery. This spermatocyte is most
likely at leptotene-zygotene-equivalent stage, since H1t signals are
absent. (c) A more advanced spermatocyte which displays faint H1t
signals in its chromatin and a relaxed but still locally restricted
accumulation of peripheral telomeres. Focal plane is at the top of
nucleus. (d) H1t-positive spermatocyte nucleus (late pachytene or
diplotene) exhibits dispersed telomeres. Focal plane is at top of
nucleus. (e) The same nucleus as in panel d, but focal plane at the
maximum nuclear diameter is shown. Telomeres are distributed over the
nuclear periphery. (f) Two spermatid nuclei encountered in the
Atm/ p53/ mouse testis show
H1t fluorescence in their chromatin and formation of chromocenters.
Nuclear DNA is counterstained with DAPI (blue).
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Atm-deficient SECs express adult-type intermediate
filament markers.
In the course of our H1t IF experiments, we
repeatedly observed intense H1t signals in the chromatin of
Atm mutant SECs (Fig. 3b), while an elevated H1t
fluorescence in control SEC nuclei was generally absent (not shown).
SECs of adult mammalian testes are mitotically inactive and represent
the supporting cell lineage which is important for meiotic
differentiation and maintenance of the blood-testis barrier (for
reviews, see references 46 and
67). Since elevated H1t IF signals could suggest
skewed or immature differentiation of Atm-deficient SECs, we
examined the expression of vimentin and cytokeratin 8 in the mutants
and control. Vimentin is an intermediate filament marker expressed by
SECs throughout development (3, 24), while cytokeratin 8 expression marks lack of SEC differentiation, as it normally occurs
only in fetal and early postnatal testes (2, 66) and in SECs
of infertile individuals or in association with testicular cancer
(10, 51, 61). IF disclosed an increased frequency of
vimentin-positive mutant SECs in relation to total testis cells (Table
2), which is most likely related to the
absence of haploid cells and/or a response to the requirements for
increased phagocytosis of the apoptotic bodies resulting from massive
germ cell degeneration in the knockouts. However, control,
Atm/, and Atm/
p53/ mutant SECs were found to exclusively express
vimentin but not cytokeratin 8. A few cytokeratin 8-positive cells
encountered in all genotypes (0.2% in the control and 0.3% in the
mutants; not shown) most likely represent cells of the epididymis
epithelium, which is known to express this intermediate filament
(24). Therefore, it appears that Atm mutant SECs
display a mature intermediate filament expression signature.
Atm localizes to the chromatin of SECs and
spermatids.
Recently, ATM has been implicated in the control of
histone H1 phosphorylation (36) and to be associated with
histone deacetylase (47). Since the nature of the increased
fluorescence of testis-specific histone H1t in Atm-deficient
SECs remained unclear, we determined the presence of ATM in SECs by IF
with MAb 2C1 (18). In the wild type, strong granular ATM IF
signals were obtained throughout the nucleoplasm of SECs and other
testis cell types (Fig. 5). A conspicuous
dearth of ATM IF signal was noted at the heterochromatin blocks of
SECs, while the euchromatic portion of the nuclei showed strong IF
(Fig. 5c). In contrast, heterochromatin blocks of round spermatids in
the same preparation showed the presence of H1t and, to a variable
extent, of ATM epitopes at these regions (Fig. 5d), which indicates
that the dearth of ATM signals in the heterochromatic chromocenters of
SECs is not due to restricted access of Abs. Dispersed granular ATM
signals were also noted throughout the nuclei of spermatocytes I and
round spermatids. In the more advance spermatids, ATM fluorescence was
less intense at the heterochromatin regions, while nuclei of elongated
spermatids showed weak or no ATM signals at all. H1t-ATM costaining
revealed that ATM was absent from nuclei of elongating spermatids which
still displayed H1t epitopes (Fig. 5d). Sperm heads completely lacked
ATM and H1t epitopes. These results are consistent with the replacement
of histones and other chromatin and nucleoplasmic components by
protamines during sperm maturation (4). Control IF
experiments to testis suspensions of Atm-deficient animals
revealed that ATM signals were generally absent from spermatogenetic
and other cell types (Fig. 5). Occasionally, weak autofluorescence was
observed in some preparations of Atm/
testicles.
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FIG. 5.
IF staining of ATM (FITC, green) and SCP3 (red) in
testis suspension cells of wild-type (a to c) and
Atm/ mice. Strong granular ATM IF signals
are dispersed throughout the nuclei of (a) spermatocytes, (b)
spermatids, and (c) SECs. Elongated sperm nuclei (c, right detail) do
not exhibit ATM epitopes. ATM signals are reduced in the
heterochromatin clusters of an SEC nucleus (c, dark-staining regions),
while ATM is present in the heterochromatin clusters of a round
spermatid (b). (d) ATM (green) and histone H1t (red) co-IF to wild-type
spermatid nuclei. The round spermatid to the right shows extensive
colocalization of ATM and H1t signals (yellow in the merge). The
elongated spermatid nucleus in the center exhibits H1t but no ATM
signals, while the condensed nucleus of a sperm head is void of IF
signals. Atm/, an
Atm/ spermatocyte (nucleus to the left,
identified by SCP3-positive SC fragments [red]) and an SEC (as
identified by vimentin [Vim.] staining around its nucleus; right
detail in red channel) lack ATM immunofluorescence. The
autofluorescence in the green channel seen at the SEC position results
from weak bleedthrough of the strong vimentin signal upon prolonged
exposure. DAPI was used as the DNA counterstain.
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The fact that most of the antibodies used in IF studies to mouse
spermatocytes were raised against portions of the human ATM
protein
(
7) prompted us to test the specificity of our ATM
MAb on
human testis preparations. Reminiscent of the IF signals
seen in the
mouse, dispersed granular ATM epitopes were detected
throughout the
nuclei of all cell types of a human testis suspension
(not shown).
Decoration of axial cores or SCs with ATM, as reported
before in mouse
spreads (
68,
69), was not detected in our
undisrupted mouse
and human spermatocytes. Altogether, it appears
that the ATM protein is
abundant in the nucleoplasm of spermatocytes,
in developing round
spermatids, and in the euchromatin of SECs.
Its absence may influence
the response of these cells to genotoxic
insult as well as to
differentiation-induced double-strand breaks
in meiotic
DNA.
SEC nuclear architecture is altered in Atm-deficient
background.
We furthermore determined whether the absence of the
Atm protein also influences nuclear architecture and telomere
distribution in SECs. In adult testes, most SECs display a unique
nuclear architecture in that they carry a large nucleolus which is
associated with one to three prominent DAPI-bright heterochromatin
clusters amidst a faintly stained euchromatin (Fig.
6a to c) (37, 38, 41). In
contrast to the adult situation, most SEC nuclei of prepubertal mouse
testes contain numerous heterochromatin clusters (16). Using
vimentin IF as an SEC marker on DAPI-stained testis preparations, we
found that 79% or more of Atm/ and
Atm/ p53/ SEC nuclei
contained four or more heterochromatin clusters of various sizes (Fig.
6d), which represents a threefold increase over the control (Table
3) and data in the literature (37, 41). It appears that the chromocenter distribution in
Atm-mutant SECs is reminiscent of that of immature SECs
(16). In addition to SECs with multiple heterochromatin
clusters, both mutants contained a reduced number of SECs with
two heterochromatin clusters, which are the predominant SEC type in the
adult mouse (Table 3) (37, 38).
View larger version (35K):
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|
FIG. 6.
SECs from control (a and b) and
Atm/ p53/ mouse testis (c
and d) stained for vimentin (TRITC; red) and hybridized with a
FITC-labeled telomere PNA probe (fluorescein, green). (a to d) SECs
positive for vimentin intermediate filament marker. (a) SEC with two
chromocenters (blue) which are associated with one or two distinct
telomere signals. (b) Vimentin-positive SEC with three chromocenters,
each associated with one telomere signal. (c) Two-chromocenter
Atm mutant SEC which shows two telomere signals at the
larger chromocenter. (d) Mutant SEC with numerous heterochromatin
clusters and telomere signals. The bar in d represents 10 µm and
applies to a through d. (e) Wild-type two-chromocenter type I SEC with
numerous minor-satellite (red) and associated telo-FISH signals
(green). The inset shows an enlarged mouse metaphase chromosome (blue)
with FISH signals of the minor-satellite probe (red) at the kinetochore
region. (f) Nucleus of a wild-type two-chromocenter type II SEC which
exhibits one strong minor-satellite signal (red) and an associated
single-telomere signal (yellow) at each DAPI-bright chromocenter. DNA
was counterstained with DAPI (blue). The bar in f represents 10 µm
and applies to e and f.
|
|
SECs of the adult mouse with one to three chromocenters have been shown
to be present in two states: type I SECs have kinetochore
dispersed
over the corresponding chromocenters, while type II
SECs have
kinetochores tightly associated and are active in ribosomal
gene
transcription (
38). To determine whether the Atm mutation
influences the activity of SECs, we identified SEC types by marking
mouse centromeres by FISH with a probe for the
kinetochore-associated
minor-satellite DNA of
M. musculus (Fig.
6e, inset). Type I SECs,
due to centromere
dispersion over their corresponding chromocenter
(
38), did
exhibit three or more minor-satellite signals per
heterochromatin
cluster (Fig.
6e). Type II SECs, due to tightly
associated centromeres
(
38), displayed one or two strong minor
satellite signals
per heterochromatin cluster (Fig.
6f). Both
Atm mutants were
found to contain significantly more type I SECs
than the control, in
which type II SECs prevailed (Table
4).
When we investigated associations of short-arm telomeres and
centromeres
in type II SECs by two-color FISH, it was found that
heterochromatin
blocks endowed with one or two minor-satellite FISH
signals generally
showed one or two strong telomere signals associated
with a minor
satellite cluster (Fig.
6f). Type I SECs generally
exhibited telomere
signals equaling the number of minor-satellite
signals associated
with a chromocenter (Fig.
6e). These data indicate
that telomere
signal distribution in
Atm mutant SECs is
related to the activity
status of SECs and that the absence of ATM does
not induce defective
telomere distribution in SECs. Therefore, it
appears that type
I SECs and those with immature nuclear architecture
but adult
intermediate filament expression profile are prevalent in the
Atm-deficient background.
| |
DISCUSSION |
Individuals with ataxia telangiectasia and mice with
Atm deficiency display gonadal atrophy and infertility.
Previous investigation has revealed, in addition to other defects (for
reviews, see references 13 and
53), that Atm/
spermatocytes display altered telomere distribution. Here we show that
the dramatic accumulation of spermatocyte I nuclei with a bouquet
topology in Atm/ mice (65) is
also present in Atm-p53 double-knockout mice. In this
background, spermatogenesis proceeds beyond the leptotene-zygotene transition, although fertility is not restored (6).
Immunostaining for SCP3 lateral element proteins and histone H1t showed
the general absence of pachytene spermatocytes in
Atm/ testes, which confirms that
spermatogenesis abrogates during zygotene equivalent stages (6,
65, 69, 97) in this background. In contrast to those from the
single-knockout mice, testicles from our Atm/
p53/ mice were found to contain some pachytene and
diplotene spermatocytes as well as a few round spermatids, which
extends earlier reports that a subpopulation of
Atm/ p53/ spermatocytes
bypass the leptotene-zygotene arrest seen in the Atm/ background (6).
Atm/ p53/ disruption
causes pronounced accumulation of spermatocytes with clustered
telomeres but fails to stall meiotic telomere movements.
ATM
function has been shown to influence telomere metabolism in human
systems (84), and telomere sequences are aberrantly associated with the nuclear matrix (85). Similar
observations have been made in spermatocytes I of
Atm/ mice, which also display an elevated
frequency of nuclei with a bouquet topology (65)a nuclear
organization motif which is rarely found in wild-type mouse
spermatocytes (32, 79) and oocytes (87). The high
frequency of bouquet cells encountered in the
Atm/ single-knockout mouse
(65; this report) is further elevated in
Atm-p53 double-knockout mouse testes. The accumulation of
prophase nuclei with bouquet topology in Atm mutant
spermatogenesis indicates that most likely all mouse spermatocytes I
pass through this under normal conditions. The accumulation of bouquet
cells in the mutants could result from the absence of an Atm-dependent
dispersion signal to clustered meiotic telomeres or, more likely, could
simply be the consequence of accumulation of spermatocytes at the
leptotene-zygotene transition, i.e., the stage when meiotic telomere
clustering normally occurs (for reviews, see references 22,
77, and 100). The higher levels of bouquet
cells observed in Atm/ p53/
mouse spermatogenesis and the presence of a few H1t-positive mid-late-pachytene and diplotene spermatocytes as well as a few round
spermatids suggest that Atm/
p53/ mouse spermatocytes progress further in
prophase I and more may reach the bouquet stage before they are doomed
to apoptosis.
If zygotene telomeres are immobilized due to
Atm deficiency,
one would expect pachytene and diplotene spermatocytes to display
a
bouquet topology in the double mutant. Interestingly, we observed
that
chromosome ends were generally scattered over the nuclear
envelope in
the H1t-positive
Atm/ p53/
late-pachytene nuclei investigated, which demonstrates that meiotic
chromosome ends are capable of exerting positional changes in
the
absence of Atm signaling. The high frequency of bouquet cells
detected
in both
Atm mutants therefore may be the consequence
of
slowed telomere movement to and at the cluster site. This could
result
from entrapment of chromosome ends by illegitimately connected
chromosome cores, aberrant telomere-nuclear matrix interactions
(
65), and a generally slowed progression through
leptotene-zygotene
in
Atm-deficient meiosis. Failure to
establish faithful homologue
pairing and to assemble recombination
complexes (
6,
7,
19,
97) may eventually trigger spermatocyte
degeneration. In the
double-knockout mice, the arrest is mediated
in a p53-independent
manner, which likely involves a
synaptic checkpoint (
62). If
such a checkpoint
operates in mammals, we would expect the few
cells which reach and pass
meiotic divisions to be derived from
nuclei that were endowed with a
premeiotic homologue association.
In these cells, homologous synaptic
pairing may have occurred
without the detrimental effects which are
elicited when separated
homologous telomeres and chromosomes with
distorted repair capacities
are mobilized during a homologue search and
tear apart chromosomes
with double-strand breaks. According to this
view, the degeneration
of most
Atm-p53 double-knockout mouse
spermatocytes would reflect
the general absence of premeiotic homologue
association in mammals
(
79).
SECs display an immature nuclear architecture in
Atm-deficient genetic background.
Since Atm
function influences meiotic and mitotic telomere behavior and SECs
usually display a few conspicuous telomere signals (telocenters) in
tight association with their corresponding heterochromatin clusters
(37, 79), we also determined whether short-arm telomere distribution of the acrocentric mouse chromosomes and nuclear architecture is affected by the Atm mutation. We used
vimentin IF to identify SECs and found, in contrast to wild-type mice, that the majority of mutant vimentin-positive SECs contained numerous heterochromatin clusters, a nuclear architecture usually observed in
SECs of immature postnatal testes (16). Without vimentin IF,
such cells would have gone unnoticed. However, the adult intermediate expression profile suggests that SEC differentiation per se is not
influenced by ATM function, since mutant SECs failed to express cytokeratin 8, a marker for immature or derailed SEC differentiation (2, 3). Besides SECs with immature heterochromatin
distribution, the mutant testes also contained SECs with two
heterochromatin clusters per nucleus, a feature frequently seen in
normal adult mice. When we monitored the activity of the latter SECs
with minor satellite and telo-FISH and applied the centromere criteria
of Haaf et al. (38) (see Results), we found that most mutant
SECs were of type I because they displayed centromeres and telomeres dispersed over the corresponding chromocenter. Furthermore, type I SECs
have been shown to be inactive in ribosomal gene transcription (38). It has been suggested that the transcription of
specific spermiogenesis genes at the onset of puberty and the initial
formation of mature sperm coincide with maturation of nuclear
architecture of SECs, i.e., the formation of one to three large
heterochromatin clusters (16). This suggestion is supported
by the immature nuclear topology and the inactive state of most mutant
SECs with adult-type nuclear architecture in
Atm/ and Atm/
p53/ mouse testes, since both mutants fail to
produce mature spermatozoa.
ATM localizes to the chromatin/nucleoplasm of SECs and haploid
spermatids.
Immunostaining of wild-type testes revealed granular
overall fluorescence of ATM epitopes in the nucleoplasm of
spermatocytes I, round spermatids, and SECs, which is consistent with a
similar localization in somatic cells (30) and mouse
spermatocytes (7). ATM IF signals were weak in elongating
mouse spermatids which still displayed H1t epitopes, while both
proteins were absent from sperm nuclei with a mature hook-shaped
morphology. Our data indicate that ATM departs or is removed from
spermatid chromatin prior to the stage when, in relation to the
tight complexation of DNA with protamines, nicks (and possibly
double-strand breaks) occur in sperm DNA (4, 86). ATM
function in haploid cells will thus most likely contribute to
surveillance of genome integrity prior to conversion of nucleosomal DNA
into transcriptionally inert nucleoprotamine. In SECs, ATM was found at
high levels throughout euchromatin, while prominent heterochromatin
clusters of this cell type showed a dearth of ATM epitopes. This
observation makes it unlikely that the lack of ATM at SEC
heterochromatin directly influences chromocenter formation in this cell
type. Reduced levels of ATM in heterochromatin of SECs (and maybe other
cell types) could be linked to a reduced efficacy of DNA repair in
inactive rodent chromatin (for a review, see reference
12). Exclusive colocalization of ATM with axial
cores or SCs, as reported previously from spread mouse spermatocytes
(68, 69), was not observed in the undisrupted mouse and
human spermatocyte nuclei in this study. Our data therefore align with
recent IF studies in mouse meiosis, which showed a dispersed
chromatin-like distribution in spermatocyte nuclei but failed to
observe an exclusive preference of ATM for SC components (7,
60).
Overall, our findings argue against a prominent defect in telomere
topology in
Atm mutant spermatocytes I and SECs. The data
can rather be reconciled with the view that the ATM protein kinase
and
its homologues are predominantly involved in mitotic and meiotic
cell
cycle control, possibly in response to DNA damage and double-strand
break formation (
35,
42,
56,
58,
96). The absence of
ATM
seems to slow progression of the initial stages of first meiotic
prophase and, due to defective synapsis, also the formation and
release
of the bouquet topology, which results in the accumulation
of
spermatocytes with clustered telomeres, which are normally
seen at the
leptotene-zygotene transition stage (
65,
79; this
report). Interestingly, the
MEC1 mutant and other
recombination-deficient
mutants of
S. cerevisiae
display defects in synapsis (
35,
48).
Abrogated
recombination has also been shown to lead to increased
bouquet
frequencies in yeast meiosis (
91), which indicates a
link
between the two processes. Since spermatogenesis in
Atm-deficient
animals represents a pathological
condition, further experiments
are needed to disclose the players in
the ATM-telomere
act.
| |
ACKNOWLEDGMENTS |
We thank Raj Pandita for technical support, C. Heyting for SCP3
antiserum, P. Moens for H1t antiserum, and G. Giese for vimentin antiserum.
This work was supported by NIH grant NS34746 to T.K.P. and the Deutsche
Forschungsgemeinschaft (350/8-2) to H.S.
| |
FOOTNOTES |
*
Corresponding author. Mailing address: Center for
Radiological Research, College of Physicians & Surgeons, Columbia
University, VC11-213, 630 West 168th St., New York, NY 10032. Phone:
(212) 305-3911. Fax: (212) 305-3229. E-mail:
tkp1{at}columbia.edu.
| |
REFERENCES |
| 1.
|
Anderson, L. K.,
H. H. Offenberg,
W. M. H. C. Verkuilen, and C. Heyting.
1997.
RecA-like proteins are components of early meiotic nodules in Lilly.
Proc. Natl. Acad. Sci. USA
94:6868-6873[Abstract/Free Full Text].
|
| 2.
|
Appert, A.,
V. Fridmacher,
O. Locquet, and S. Magre.
1998.
Patterns of keratins 8, 18 and 19 during gonadal differentiation in the mouse: sex- and time-dependent expression of keratin 19.
Differentiation
63:273-284[Medline].
|
| 3.
|
Aumüller, G.,
C. Schulze, and C. Viebahn.
1992.
Intermediate filaments in Sertoli cells.
Microsc. Res. Tech.
20:50-72[CrossRef][Medline].
|
| 4.
|
Balhorn, R.
1982.
A model for the structure of chromatin in mammalian sperm.
J. Cell Biol.
93:298-305[Abstract/Free Full Text].
|
| 5.
|
Barlow, C.,
S. Hirotsune,
R. Paylor,
M. Liyanage,
M. Eckhaus,
F. Collins,
Y. Shiloh,
J. N. Crawley,
T. Ried,
D. Tagle, and A. Wynshaw-Boris.
1996.
Atm-deficient mice: a paradigm of ataxia telangiectasia.
Cell
86:159-171[CrossRef][Medline].
|
| 6.
|
Barlow, C.,
M. Liyanage,
P. B. Moens,
C. X. Deng,
T. Ried, and A. Wynshaw-Boris.
1997.
Partial rescue of the prophase I defects of Atm-deficient mice by p53 and p21 null alleles.
Nat. Genet.
17:462-466[CrossRef][Medline].
|
| 7.
|
Barlow, C.,
M. Liyanage,
P. B. Moens,
M. Tarsounas,
K. Nagashima,
K. Brown,
S. Rottinghaus,
S. P. Jackson,
D. Tagle,
T. Ried, and A. Wynshaw-Boris.
1998.
Atm deficiency results in severe meiotic disruption as early as leptonema of prophase I.
Development
125:4007-4017[Abstract].
|
| 8.
|
Baskaran, R.,
L. D. Wood,
L. L. Whitaker,
C. E. Canman,
S. E. Morgan,
Y. Xu,
D. Baltimore,
M. B. Kastan, and J. Wang.
1997.
Ataxia telangiectasia mutant protein activates c-Abl tyrosine kinase in response to ionizing radiation.
Nature
387:516-519[CrossRef][Medline].
|
| 9.
|
Bentley, N. J.,
D. A. Holtzman,
G. Flaggs,
K. S. Keegan,
A. DeMaggio,
J. C. Ford,
M. Hoekstra, and A. M. Carr.
1996.
The Schizosaccharomyces pombe rad3 checkpoint gene.
EMBO J.
15:6641-6651[Medline].
|
| 10.
|
Bergmann, M., and S. Kliesch.
1994.
The distribution pattern of cytokeratin and vimentin immunoreactivity in testicular biopsies of infertile men.
Anat. Embryol. (Berlin)
190:515-520[Medline].
|
| 11.
|
Blackburn, E. H., and C. W. Greider (ed.).
1995.
Telomeres. Cold Spring Harbor monograph series no. 29.
Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y.
|
| 12.
|
Bohr, V. A., and K. Wassermann.
1988.
DNA repair at the level of the gene.
Trends Biochem. Sci.
13:429-433[CrossRef][Medline].
|
| 13.
|
Bridges, B. A., and D. G. Harnden.
1982.
Ataxia telangiectasia: a cellular and molecular link between cancer, neuropathology, and immune deficiency.
Wiley, Chichester, England.
|
| 14.
|
Brown, K. D.,
C. Barlow, and A. Wynshaw-Boris.
1999.
Multiple ATM-dependent pathways: an explanation for pleiotropy.
Am. J. Hum. Genet.
64:46-50[CrossRef][Medline].
|
| 15.
|
Brush, G. S.,
D. M. Morrow,
P. Hieter, and T. J. Kelly.
1996.
The ATM homologue MEC1 is required for phosphorylation of replication protein A in yeast.
Proc. Natl. Acad. Sci. USA
93:15075-15080[Abstract/Free Full Text].
|
| 16.
|
Chandley, A. C., and R. M. Speed.
1995.
A reassessment of Y chromosome behaviour in germ cells and Sertoli cells of the mouse as revealed by in situ hybridisation.
Chromosoma
104:282-286[Medline].
|
| 17.
|
Chaturvedi, P.,
W. K. Eng,
Y. Zhu,
M. R. Mattern,
R. Mishra,
M. R. Hurle,
X. Zhang,
R. S. Annan,
Q. Lu,
L. F. Faucette,
G. F. Scott,
X. Li,
S. A. Carr,
R. K. Johnson,
J. D. Winkler, and B. B. Zhou.
1999.
Mammalian Chk2 is a downstream effector of the ATM-dependent DNA damage checkpoint pathway.
Oncogene
18:4047-4054[CrossRef][Medline].
|
| 18.
|
Chen, G., and E. Y.-H. Lee.
1996.
The product of the ATM gene is a 370 kDa nuclear phosphoprotein.
J. Biol. Chem.
271:33693-33697[Abstract/Free Full Text].
|
| 19.
|
Chen, G.,
S. S. Yuan,
W. Liu,
Y. Xu,
K. Trujillo,
B. Song,
F. Cong,
S. P. Goff,
Y. Wu,
R. Arlinghaus,
D. Baltimore,
P. J. Gasser,
M. S. Park,
P. Sung, and E. Y.-H. Lee.
1999.
Radiation-induced assembly of Rad51 and Rad52 recombination complex requires ATM and c-Abl.
J. Biol. Chem.
274:12748-12752[Abstract/Free Full Text].
|
| 20.
|
Cockell, M., and S. M. Gasser.
1999.
Nuclear compartments and gene regulation.
Curr. Opin. Genet. Dev.
9:199-205[CrossRef][Medline].
|
| 21.
|
Counter, C. M.,
A. A. Avilion,
C. E. LeFeuvre,
N. G. Stewart,
C. W. Greider,
C. B. Harley, and S. Bacchetti.
1992.
Telomere shortening associated with chromosome instability is arrested in immortal cells which express telomerase activity.
EMBO J.
11:1921-1929[Medline].
|
| 22.
|
de Lange, T.
1998.
Ending up with the right partner.
Nature
392:753-754[CrossRef][Medline].
|
| 23.
|
Dernburg, A. F.,
J. W. Sedat,
W. Z. Cande, and H. W. Bass.
1995.
The cytology of telomeres, p. 295-338.
In
E. H. Blackburn, and C. W. Greider (ed.), Telomeres. Cold Spring Harbor monograph series no. 29. Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y.
|
| 24.
|
Dinges, H. P.,
K. Zatloukal,
C. Schmid,
S. Mair, and G. Wirnsberger.
1991.
Co-expression of cytokeratin and vimentin filaments in rete testis and epididymis: an immunohistochemical study.
Virchows Arch. A Pathol. Anat. Histopathol.
418:119-127[CrossRef][Medline].
|
| 25.
|
Drabent, B.,
C. Bode,
B. Bramlage, and D. Doenecke.
1996.
Expression of the mouse testicular histone gene H1t during spermatogenesis.
Histochem. Cell Biol.
106:247-251[Medline].
|
| 26.
|
Duggal, R. N.,
Z. F. Zakeri,
C. Ponzetto, and D. J. Wolgemuth.
1987.
Differential expression of the c-Abl proto-oncogene and the homeo box-containing gene Hox 1.4 during mouse spermatogenesis.
Ann. N.Y. Acad. Sci.
513:112-127[Medline].
|
| 27.
|
Elson, A.,
Y. Wang,
C. J. Daugherty,
C. C. Morton,
F. Zhou,
J. Campos-Torres, and P. Leder.
1996.
Pleiotropic defects in ataxia-telangiectasia protein-deficient mice.
Proc. Natl. Acad. Sci. USA
93:13084-13089[Abstract/Free Full Text].
|
| 28.
|
Flaggs, G.,
A. W. Plug,
K. M. Dunks,
K. E. Mundt,
J. C. Ford,
M. R. Quiggle,
E. M. Taylor,
C. H. Westphal,
T. Ashley,
M. F. Hoekstra, and A. M. Carr.
1997.
Atm-dependent interactions of a mammalian chk1 homolog with meiotic chromosomes.
Curr. Biol.
7:977-986[CrossRef][Medline].
|
| 29.
|
Gasior, S. L.,
A. K. Wong,
Y. Kora,
A. Shinohara, and D. K. Bishop.
1998.
Rad52 associates with RPA and functions with rad55 and rad57 to assemble meiotic recombination complexes.
Genes Dev.
12:2208-2221[Abstract/Free Full Text].
|
| 30.
|
Gately, D. P.,
J. C. Hittle,
G. K. T. Chan, and T. J. Yen.
1998.
Characterization of ATM expression, localization, and associated DNA-dependent protein kinase activity.
Mol. Biol. Cell
9:2361-2374[Abstract/Free Full Text].
|
| 31.
|
Giese, G.,
M. Kubbies, and P. Traub.
1990.
Alterations of cell cycle kinetics and vimentin expression in asynchronous, TPA-treated MPC-11 mouse plasmacytoma cells.
Exp. Cell Res.
190:179-184[CrossRef][Medline].
|
| 32.
|
Glamann, J.
1986.
Crossing over in the male mouse as analyzed by recombination nodules and bars.
Carlsberg Res. Commun.
51:143-162[CrossRef].
|
| 33.
|
Golub, E. I.,
R. C. Gupta,
T. Haaf,
M. S. Wold, and C. M. Radding.
1998.
Interaction of human rad51 recombination protein with single-stranded DNA binding protein, RPA.
Nucleic Acids Res.
26:5388-5393[Abstract/Free Full Text].
|
| 34.
|
Greenwell, P. W.,
S. L. Kronmal,
S. E. Porter,
J. Gassenhuber,
B. Obermaier, and T. D. Petes.
1995.
TEL1, a gene involved in controlling telomere length in S. cerevisiae, is homologous to the human ataxia telangiectasia gene.
Cell
82:823-829[CrossRef][Medline].
|
| 35.
|
Grushcow, J. M.,
T. M. Holzen,
K. J. Park,
T. Weinert,
M. Lichten, and D. K. Bishop.
1999.
Saccharomyces cerevisiae checkpoint genes MEC1, RAD17 and RAD24 are required for normal meiotic recombination partner choice.
Genetics
153:607-620[Abstract/Free Full Text].
|
| 36.
|
Guo, C. Y.,
Y. Wang,
D. L. Brautigan, and J. M. Larner.
1999.
Histone H1 dephosphorylation is mediated through a radiation-induced signal transduction pathway dependent on ATM.
J. Biol. Chem.
274:18715-18720[Abstract/Free Full Text].
|
| 37.
|
Guttenbach, M.,
M. J. Martinez-Exposito,
W. Engel, and M. Schmid.
1996.
Interphase chromosome arrangement in Sertoli cells of adult mice.
Biol. Reprod.
54:980-986[Abstract].
|
| 38.
|
Haaf, T.,
C. Steinlein, and M. Schmid.
1990.
Nucleolar transcriptional activity in mouse Sertoli cells is dependent on centromere arrangement.
Exp. Cell Res.
191:157-160[CrossRef][Medline].
|
| 39.
|
Hardin, J. D.,
S. Boast,
P. L. Schwartzberg,
G. Lee,
F. W. Alt,
A. M. Stall, and S. P. Goff.
1996.
Abnormal peripheral lymphocyte function in c-abl mutant mice.
Cell. Immunol.
172:100-107[CrossRef][Medline].
|
| 40.
|
Harnden, D. G.
1994.
The nature of ataxia-telangiectasia: problems and perspectives.
Int. J. Radiat. Biol.
66:S13-S19[Medline].
|
| 41.
|
Hsu, T. C.,
J. E. Cooper,
M. L. Mace, Jr., and B. R. Brinkley.
1971.
Arrangement of centromeres in mouse cells.
Chromosoma
34:73-87[CrossRef][Medline].
|
| 42.
|
Johnson, R. T.,
E. Gotoh,
A. M. Mullinger,
A. J. Ryan,
Y. Shiloh,
Y. Ziv, and S. Squires.
1999.
Targeting double-strand breaks to replicating DNA identifies a subpathway of DSB repair that is defective in ataxia-telangiectasia cells.
Biochem. Biophys. Res. Commun.
261:317-325[CrossRef][Medline].
|
| 43.
|
Kastan, M. B.,
Q. Zhan,
W. S. El Deiry,
F. Carrier,
T. Jacks,
W. V. Walsh,
B. S. Plunkett,
B. Vogelstein, and A. J. Fornace, Jr.
1992.
A mammalian cell cycle checkpoint pathway utilizing p53 and GADD45 is defective in ataxia-telangiectasia.
Cell
71:587-597[CrossRef][Medline].
|
| 44.
|
Keegan, K. S.,
D. A. Holtzman,
A. W. Plug,
E. R. Christenson,
E. E. Brainerd,
G. Flaggs,
N. J. Bentley,
E. M. Taylor,
M. S. Meyn,
S. B. Moss,
A. M. Carr,
T. Ashley, and M. E. Hoekstra.
1996.
The Atr and Atm protein kinases associate with different sites along meiotically pairing chromosomes.
Genes Dev.
10:2423-2437[Abstract/Free Full Text].
|
| 45.
|
Keith, C. T., and S. L. Schreiber.
1995.
PIK-related kinases: DNA repair, recombination, and cell cycle checkpoint.
Science
270:50-51.
|
| 46.
|
Kierszenbaum, A. L.
1994.
Mammalian spermatogenesis in vivo and in vitro: a partnership of spermatogenic and somatic cell lineages.
Endocrine Rev.
15:116-134[Abstract/Free Full Text].
|
| 47.
|
Kim, G. D.,
Y. H. Choi,
A. Dimtchev,
S. J. Jeong,
A. Dritschilo, and M. Jung.
1999.
Sensing of ionizing radiation-induced DNA damage by ATM through interaction with histone deacetylase.
J. Biol. Chem.
274:31127-31130[Abstract/Free Full Text].
|
| 48.
|
Kleckner, N.,
R. Padmore, and D. K. Bishop.
1991.
Meiotic chromosome metabolism: one view.
Cold Spring Harbor Symp. Quant. Biol.
56:729-743[Abstract/Free Full Text].
|
| 49.
|
Kojis, T. L.,
R. A. Gatti, and R. S. Sparkes.
1991.
The cytogenetics of ataxia telangiectasia.
Cancer Genet. Cytogenet.
56:143-156[CrossRef][Medline].
|
| 50.
|
Kruh, G. D.,
R. Perego,
T. Miki, and S. A. Aaronson.
1990.
The complete coding sequence of arg defines the Abelson subfamily of cytoplasmic tyrosine kinases.
Proc. Natl. Acad. Sci. USA
87:5802-5806[Abstract/Free Full Text].
|
| 51.
|
Kurohmaru, M.,
Y. Kanai, and Y. Hayashi.
1992.
A cytological and cytoskeletal comparison of Sertoli cells without germ cell and those with germ cells using the W/WV mutant mouse.
Tissue Cell
24:895-903[CrossRef][Medline].
|
| 52.
|
Lammers, J. H. M.,
H. H. Offenberg,
M. van Aalderen,
A. C. Vink,
A. J. Dietrich, and C. Heyting.
1994.
The gene encoding a major component of the lateral elements of synaptonemal complexes of the rat is related to X-linked lymphocyte-regulated genes.
Mol. Cell. Biol.
14:1137-1146[Abstract/Free Full Text].
|
| 53.
|
Lavin, M. F.,
P. Concannon, and R. A. Gatti.
1999.
Eighth international workshop on ataxia-telangiectasia (ATW8).
Cancer Res.
59:3845-3849[Free Full Text].
|
| 54.
|
Loidl, J.
1990.
The initiation of meiotic chromosome pairing: the cytological view.
Genome
33:759-778[Medline].
|
| 55.
|
Luderus, M. E. E.,
B. van Steensel,
L. Chong,
O. C. M. Sibon,
F. F. M. Cremers, and T. de Lange.
1996.
Structure, subnuclear distribution, and nuclear matrix association of the mammalian telomeric complex.
J. Cell Biol.
135:867-881[Abstract/Free Full Text].
|
| 56.
|
Lydall, D.,
Y. Nikolsky,
D. K. Bishop, and T. Weinert.
1996.
A meiotic recombination checkpoint controlled by mitotic checkpoint genes.
Nature
383:840-843[CrossRef][Medline].
|
| 57.
|
Meistrich, M. L., and W. A. Brock.
1987.
Proteins of the meiotic cell nucleus, p. 333-353.
In
P. B. Moens (ed.), Meiosis. Academic Press, New York, N.Y.
|
| 58.
|
Meyn, M. S.
1995.
Ataxia-telangiectasia and cellular responses to DNA damage.
Cancer Res.
55:5991-6001[Abstract/Free Full Text].
|
| 59.
|
Moens, P. B.
1995.
Histones H1 and H4 of surface-spread meiotic chromosomes.
Chromosoma
104:169-174[Medline].
|
| 60.
|
Moens, P. B.,
M. Tarsounas,
T. Morita,
T. Habu,
S. T. Rottinghaus,
R. Freire,
S. P. Jackson,
C. Barlow, and A. Wynshaw-Boris.
1999.
The association of ATR protein with mouse meiotic chromosome cores.
Chromosoma
108:95-102[CrossRef][Medline].
|
| 61.
|
Moll, R.,
W. W. Franke,
D. L. Schiller,
B. Geiger, and R. Krepler.
1982.
The catalog of human cytokeratins: patterns of expression in normal epithelia, tumors and cultured cells.
Cell
31:11-24[CrossRef][Medline].
|
| 62.
|
Odorisio, T.,
T. A. Rodriguez,
E. P. Evans,
A. R. Clarke, and P. S. Burgoyne.
1998.
The meiotic checkpoint monitoring synapsis eliminates spermatocytes via p53-independent apoptosis.
Nat. Genet.
18:257-261[CrossRef][Medline].
|
| 63.
|
Pandita, T. K.,
S. Pathak, and C. Geard.
1995.
Chromosome end association, telomeres and telomerase activity in ataxia telangiectasia cells.
Cytogenet. Cell Genet.
71:86-93[Medline].
|
| 64.
|
Pandita, T. K.,
E. J. Hall,
T. K. Hei,
M. A. Piatyszek,
W. E. Wright,
C. Q. Piao,
R. K. Pandita,
J. V. Willey,
C. R. Geard,
M. B. Kastan, and J. W. Shay.
1996.
Chromosome end-to-end associations and telomerase activity during cancer progression in human cells after treatment with a-particles simulating radon progeny.
Oncogene
13:1423-1430[Medline].
|
| 65.
|
Pandita, T. K.,
C. H. Westphal,
M. Anger,
S. G. Sawant,
C. R. Geard,
R. K. Pandita, and H. Scherthan.
1999.
Atm inactivation results in aberrant telomere clustering during meiotic prophase.
Mol. Cell. Biol.
19:5096-5105[Abstract/Free Full Text].
|
| 66.
|
Paranko, J.,
M. Kallajoki,
L. J. Pelliniemi,
V. P. Lehto, and I. Virtanen.
1986.
Transient coexpression of cytokeratin and vimentin in differentiating rat Sertoli cells.
Dev. Biol.
117:35-44[CrossRef][Medline].
|
| 67.
|
Parvinen, M.,
K. K. Vihko, and J. Toppari.
1986.
Cell interactions during the seminiferous epithelial cycle.
Int. Rev. Cytol.
104:115-151[Medline].
|
| 68.
|
Plug, A. W.,
A. H. Peters,
Y. Xu,
K. S. Keegan,
M. F. Hoekstra,
D. Baltimore,
P. de Boer, and T. Ashley.
1997.
ATM and RPA in meiotic chromosome synapsis and recombination.
Nat. Genet.
17:457-461[CrossRef][Medline].
|
| 69.
|
Plug, A. W.,
A. H. Peters,
K. S. Keegan,
M. F. Hoekstra,
P. de Boer, and T. Ashley.
1998.
Changes in protein composition of meiotic nodules during mammalian meiosis.
J. Cell Sci.
111:413-423[Abstract].
|
| 70.
|
Ponzetto, C., and D. J. Wolgemuth.
1985.
Haploid expression of a unique c-Abl transcript in the mouse male germ line.
Mol. Cell. Biol.
5:1791-1794[Abstract/Free Full Text].
|
| 71.
|
Price, C. M.
1999.
Telomeres and telomerase: broad effects on cell growth.
Curr. Opin. Genet. Dev.
9:218-224[CrossRef][Medline].
|
| 72.
|
Rockmill, B., and G. S. Roeder.
1998.
Telomere-mediated chromosome pairing during meiosis in budding yeast.
Genes Dev.
12:2574-2586[Abstract/Free Full Text].
|
| 73.
|
Roeder, G. S.
1997.
Meiotic chromosomes: it takes two to tango.
Genes Dev.
11:2600-2621[Free Full Text].
|
| 74.
|
Sanchez, Y.,
B. A. Desany,
W. J. Jones,
Q. Liu,
B. Wang, and S. J. Elledge.
1996.
Regulation of RAD53 by the ATM-like kinases MEC1 and TEL1 in yeast cell cycle checkpoint pathways.
Science
271:357-360[Abstract].
|
| 75.
|
Savitsky, K.,
A. Bar-Shira,
S. Gilad,
G. Rotman,
Y. Ziv,
L. Vanagaite,
D. A. Tagle,
S. Smith,
T. Uziel,
S. Sfez,
M. Ashkenazi,
I. Pecker,
M. Frydman,
R. Harnik,
S. R. Patanjali,
A. Simmons,
G. A. Clines,
A. Sartiel,
R. A. Gatti,
L. Chessa,
O. Sanyal,
M. F. Lavin,
N. G. J. Jaspers,
A. M. R. Taylor,
C. F. Arlett,
T. Miki,
S. M. Weissman,
M. Lovett,
F. S. Collins, and Y. Shiloh.
1995.
A single ataxia telangiectasia gene with a product similar to PI-3 kinase.
Science
268:1749-1753[Abstract/Free Full Text].
|
| 76.
|
Schalk, J. A.,
A. J. Dietrich,
A. C. Vink,
H. H. Offenberg,
M. van Aalderen, and C. Heyting.
1998.
Localization of SCP2 and SCP3 protein molecules within synaptonemal complexes of the rat.
Chromosoma
107:540-548[CrossRef][Medline].
|
| 77.
|
Scherthan, H.
1997.
Chromosome behavior in earliest meiotic prophase, p. 217-248.
In
H. Gill, J. S. Parker, and M. Puertas (ed.), Chromosomes today, vol. 12. Chapman and Hall, London, England.
|
| 78.
|
Scherthan, H., and T. Cremer.
1994.
Methodology of non isotopic in situ-hybridization in paraffin embedded tissue sections.
Methods Mol. Genet.
5:223-238.
|
| 79.
|
Scherthan, H.,
S. Weich,
H. Schwegler,
C. Heyting,
M. Harle, and T. Cremer.
1996.
Centromere and telomere movement during early prophase of mouse and man are associated with the onset of chromosome pairing.
J. Cell Biol.
134:1109-1125[Abstract/Free Full Text].
|
| 80.
|
Shafman, T.,
K. K. Khanna,
P. Kedar,
K. Spring,
S. Kozlov,
T. Yen,
K. Hobson,
M. Gatei,
N. Zhang,
D. Watters,
M. Egerton,
Y. Shiloh,
S. Kharbanda,
D. Kufe, and M. F. Lavin.
1997.
Interactions between ATM protein and c-Abl in response to DNA damage.
Nature
387:520-523[CrossRef][Medline].
|
| 81.
|
Shiloh, Y.
1995.
Ataxia-telangiectasia: closer to unraveling the mystery.
Eur. J. Hum. Genet.
3:116-138[Medline].
|
| 82.
|
Shinohara, A.,
H. Ogawa, and T. Ogawa.
1992.
Rad51 protein involved in repair and recombination in S. cerevisiae is a RecA-like protein.
Cell
69:457-470[CrossRef][Medline].
|
| 83.
|
Shinohara, A.,
S. Gasior,
T. Ogawa,
N. Kleckner, and D. K. Bishop.
1997.
Saccharomyces cerevisiae recA homologues RAD51 and DMC1 have both distinct and overlapping roles in meiotic recombination.
Genes Cells
2:615-629[Abstract].
|
| 84.
|
Smilenov, L. B.,
S. E. Morgan,
W. Mellado,
S. G. Sawant,
M. B. Kastan, and T. K. Pandita.
1997.
Influence of ATM function on telomere metabolism.
Oncogene
15:2659-2665[CrossRef][Medline].
|
| 85.
|
Smilenov, L. B.,
S. Dhar, and T. K. Pandita.
1999.
Altered telomere nuclear matrix interactions and nucleosomal periodicity in ataxia telangiectasia cells before and after ionizing radiation treatment.
Mol. Cell. Biol.
19:6963-6971[Abstract/Free Full Text].
|
| 86.
|
Smith, A., and T. Haaf.
1998.
DNA nicks and increased sensitivity of DNA to fluorescence in situ end labeling during functional spermiogenesis.
Biotechniques
25:496-502[Medline].
|
| 87.
|
Speed, R. M.
1982.
Meiosis in the foetal mouse ovary.
Chromosoma
85:427-437[CrossRef][Medline].
|
| 88.
|
Suzuki, K.,
S. Kodama, and M. Watanabe.
1999.
Recruitment of ATM protein to double strand DNA irradiated with ionizing radiation.
J. Biol. Chem.
274:25571-25575[Abstract/Free Full Text].
|
| 89.
|
Tarsounas, M.,
T. Morita,
R. E. Pearlman, and P. B. Moens.
1999.
RAD51 and DMC1 form mixed complexes associated with mouse meiotic chromosome cores and synaptonemal complexes.
J. Cell Biol.
147:207-220[Abstract/Free Full Text].
|
| 90.
|
Terasawa, M.,
A. Shinohara,
Y. Hotta,
H. Ogawa, and T. Ogawa.
1995.
Localization of RecA-like recombination proteins on chromosomes of the lily at various meiotic stages.
Genes Dev.
9:925-934[Abstract/Free Full Text].
|
| 91.
|
Trelles-Sticken, E.,
J. Loidl, and H. Scherthan.
1999.
Bouquet formation in budding yeast: Initiation of recombination is not required for meiotic telomere clustering.
J. Cell Sci.
112:651-658[Abstract].
|
| 92.
|
Tybulewicz, V. L.,
C. E. Crawford,
P. K. Jackson,
R. T. Bronson, and R. C. Mulligan.
1991.
Neonatal lethality and lymphopenia in mice with a homozygous disruption of the c-abl proto-oncogene.
Cell
65:1153-1163[CrossRef][Medline].
|
| 93.
|
Westphal, C. H.
1997.
Cell-cycle signaling: Atm displays its many talents.
Curr. Biol.
7:789-792.
|
| 94.
|
Westphal, C. H.,
S. Rowan,
C. Schmaltz,
A. Elson,
D. E. Fisher, and P. Leder.
1997.
Atm and p53 cooperate in apoptosis and suppression of tumorigenesis, but not in resistance to acute radiation toxicity.
Nat. Genet.
16:397-401[CrossRef][Medline].
|
| 95.
|
Wong, A. K. C., and J. B. Rattner.
1988.
Sequence organization and cytological localization of the minor satellite of mouse.
Nucleic Acids Res.
16:11645-11661[Abstract/Free Full Text].
|
| 96.
|
Xie, G.,
R. C. Habbersett,
Y. Jia,
S. R. Peterson,
B. E. Lehnert,
E. M. Bradbury, and J. A. D'Anna.
1998.
Requirements for p53 and the ATM gene product in the regulation of G1/S and S phase checkpoints.
Oncogene
16:721-736[CrossRef][Medline].
|
| 97.
|
Xu, Y.,
T. Ashley,
E. E. Brainerd,
R. T. Bronson,
M. S. Meyn, and D. Baltimore.
1996.
Targeted disruption of ATM leads to growth retardation, chromosomal fragmentation during meiosis, immune defects, and thymic lymphoma.
Genes Dev.
10:2411-2422[Abstract/Free Full Text].
|
| 98.
|
Xu, Y., and D. Baltimore.
1996.
Dual roles of ATM in the cellular response to radiation and in cell growth control.
Genes Dev.
10:2401-2410[Abstract/Free Full Text].
|
| 99.
|
Zakian, V. A.
1995.
Saccharomyces telomeres: function, structure and replication, P. 107-138.
In
E. H. Blackburn, and C. W. Greider (ed.), Telomeres. Cold Spring Harbor monograph series no. 29. Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y.
|
| 100.
|
Zickler, D., and N. Kleckner.
1998.
The leptotene-zygotene transition of meiosis.
Annu. Rev. Genet.
32:619-697[CrossRef][Medline].
|
Molecular and Cellular Biology, October 2000, p. 7773-7783, Vol. 20, No. 20
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