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Molecular and Cellular Biology, October 1999, p. 7011-7019, Vol. 19, No. 10
Department of Molecular
Genetics1 and Division of Developmental
Therapeutics, Cancer Center,2 University of
Illinois College of Medicine, Chicago, Illinois 60607, and
Department of Human Genetics3 and
Molecular Biology Program,4 Memorial
Sloan-Kettering Cancer Center, New York, New York 10021
Received 6 April 1999/Returned for modification 5 May 1999/Accepted 20 July 1999
The mechanism by which cyclin-dependent kinase 4 (CDK4) regulates
cell cycle progression is not entirely clear. Cyclin D/CDK4 appears to
initiate phosphorylation of retinoblastoma protein (Rb) leading to
inactivation of the S-phase-inhibitory action of Rb. However, cyclin
D/CDK4 has been postulated to act in a noncatalytic manner to regulate
the cyclin E/CDK2-inhibitory activity of p27Kip1 by
sequestration. In this study we investigated the roles of CDK4 in cell
cycle regulation by targeted disruption of the mouse CDK4
gene. CDK4 In mammalian cells, the balance of
growth-stimulatory and -inhibitory signals regulates the transition
between proliferation and quiescence (42). Cyclin-dependent
kinases (CDKs) activated by the regulatory subunits, cyclins, control
cell cycle progression in all eukaryotes (21, 48, 52). Among
several cyclin-CDK complexes, cyclin D- and cyclin E-dependent kinases
play critical roles in regulating G1 progression and entry
into S phase. D-type cyclins bind to and activate CDK4 during early to
mid-G1. This is followed by activation of CDK2 in complex
with cyclin E during late G1. These two types of CDKs seem
to collaborate to determine the rate of the G1 to S
transition (1, 40, 45). After cells enter S phase, cyclin A
binds to and activates CDK2, which is required for maintenance of DNA
replication (41). Three D-type cyclins (D1, D2, and
D3) are expressed in tissue-specific but overlapping manners
(32), whereas CDK4 and CDK2 and cyclins E and A are
ubiquitously expressed. D-type cyclins also activate CDK6, a
kinase closely related to CDK4 (2, 35). Although CDK6 and
CDK4 are coexpressed in many cell types, it is unclear whether these
two CDKs have completely overlapping functions.
Cyclin D-CDK4 plays an important role in inactivating the
S-phase-inhibitory action of the retinoblastoma protein (Rb) by phosphorylation (10, 11, 19, 22, 60). During early
G1, Rb is in a hypophosphorylated form and sequesters the
E2F family of transcription factors (39). As cells proceed
through G1, Rb is progressively phosphorylated, resulting
in release of E2F from the sequestration and activation of a number of
S-phase-specific genes by E2F. Accumulating evidence suggests that the
kinase activity of cyclin D-CDK4 is at least partly responsible for the
initial phosphorylation of Rb at specific sites, which allows
subsequent phosphorylation of other sites, presumably by cyclin E-CDK2
(24, 29). Other Rb-related proteins, such as p130 and p107,
could also be regulated by cyclin D-CDK4 in a phosphorylation-dependent manner (3, 9, 61), although details are not completely understood.
Cyclin D- and cyclin E-dependent kinases are inhibited by association
with CDK inhibitor proteins, including p27Kip1
(53). We previously demonstrated that p27 plays a
rate-limiting role in the transition between proliferation and
quiescence by creating and examining mice deficient in p27
(25). T lymphocytes, oligodendrocytes, keratinocytes and
ovarian granulosa cells in p27-deficient mice were refractory to
growth-inhibitory signals (6, 30, 36, 59). The
gigantism-like phenotype of p27-deficient mice further suggested that
p27 determines the replicative capacity of cells in response to
growth-inhibitory signals, while it remained unclear how p27 plays this
role by interacting with multiple cyclin-CDK complexes. Although p27
has been categorized as a general inhibitor of the G1-S
CDKs, cyclin D-CDK4 and cyclin E (or A)-CDK2 show different
susceptibilities to inhibition by p27 (57). In proliferating cells, the association of p27 does not necessarily inhibit cyclin D-CDK4, whereas it always inactivates cyclin E (or A)-CDK2. Thus, cyclin D-CDK4 may sequester p27, controlling the amount of p27 available for inhibition of CDK2 activity. Therefore, cyclin D-CDK4 may
play both catalytic and noncatalytic roles in the regulation of
G1 progression. In this study, we attempted to determine
the indispensable role(s) of CDK4 in cell cycle regulation by targeted disruption of the mouse CDK4 gene. Our analyses of CDK4-null
mice and fibroblasts from these mice suggested that at least part of CDK4's rate-limiting role for the G0-S transition consists
of negative control of the activity of p27 by sequestration.
Cloning and vector construction.
The CDK4 gene
with its 5' and 3' flanking regions was cloned from a mouse 129/sv
genomic library (Stratagene), with murine CDK4 cDNA (31)
used as a probe. Exons 2 to 5 and a 3' portion of exon 1 were deleted
and replaced with the functional neomycin resistance gene cassette
prepared from the pMC1-neo-poly(A)+ plasmid. A herpes
simplex virus (HSV) thymidine kinase gene was inserted adjacent to the
3' end of the CDK4 genomic fragment for the negative selection
(47).
Targeted disruption of the CDK4 gene in ES cells.
CJ-7 ES
cells (25, 58) were electroporated with the targeting vector
and selected with G418 and ganciclovir, as described previously
(25). The probe for the Southern analysis was a 1.2-kb BamHI-EcoRI genomic fragment 5' upstream to the
region used for the targeting vector. We injected four of these clones
individually into C57BL/6 blastocyst embryos (day 3.5), and the
resulting male chimeras were crossed with wild-type C57BL/6 females to
generate CDK4+/ Analyses of fertility and diabetes.
We examined the mating
ability and fertility of CDK4 Histology.
Tissues were fixed with 10% buffered formalin,
embedded in paraffin, and cut in 3-µm-thick sections with a
microtome. Slides were stained with hematoxylin and eosin
(20).
Culture of embryonic fibroblasts.
Fibroblasts were prepared
from day 12.5 embryos according to standard protocols (20)
and cultured in Dulbecco's modified minimum essential medium (DMEM)
supplemented with 10% fetal bovine serum (FBS). Cells from one embryo
were cultured in a 60-mm-diameter culture dish until confluent (passage
0) and then kept under subconfluent conditions by passages with a
dilution of 1:3. Following three passages, cells were serum starved
by 72-h culture in DMEM supplemented with 0.1% FBS and then
stimulated by 10% FBS. At different times, cells were pulse-labeled
with 100 µM bromodeoxyuridine (BrdU) for 30 min and then harvested.
For flow cytometry, cells were fixed with 70% ethanol, stained with 10 µg of fluorescein-conjugated anti-BrdU antibody (Pharmingen)/ml and
then stained with 50 µg of propidium iodide/ml in the presence
of 200 µg of RNase A/ml for 30 min at 37°C according to the
manufacturer's protocols. The samples were analyzed with a FACScan
(Becton Dickinson), and the data were processed with Cell Quest (Becton
Dickinson) software.
Immunoprecipitation and immunoblotting.
Cells were lysed by
sonication in NP-40 lysis buffer (50 mM HEPES-KOH [pH 7.5], 150 mM
NaCl, 0.1% NP-40, 10% glycerol, 1 mM EDTA, 2.5 mM EGTA, 1 mM
dithiothreitol, 10 mM CDK4 gene targeting.
First, we generated a
CDK4-null mouse strain, using a standard gene targeting
technique with murine embryonic stem (ES) cells (47). We
constructed a genomic homologous recombination vector in which 81% of
the CDK4 coding sequence (from the middle of exon 1 through exon 5) and
the intervening introns were replaced with a neomycin resistance gene
(Fig. 1a). Of the 348 ES clones examined after transfection and selection, 6 had legitimate homologous recombination, exhibiting the CDK4+/
0270-7306/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Targeted Disruption of CDK4 Delays Cell Cycle Entry
with Enhanced p27Kip1 Activity
ABSTRACT
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
/ mice survived embryogenesis and
showed growth retardation and reproductive dysfunction associated with
hypoplastic seminiferous tubules in the testis and perturbed corpus
luteum formation in the ovary. These phenotypes appear to be opposite
to those of p27-deficient mice such as gigantism and gonadal
hyperplasia. A majority of CDK4/ mice
developed diabetes mellitus by 6 weeks, associated with degeneration of
pancreatic islets. Fibroblasts from CDK4/
mouse embryos proliferated similarly to wild-type embryonic fibroblasts under conditions that promote continuous growth. However, quiescent CDK4/ fibroblasts exhibited a substantial
(~6-h) delay in S-phase entry after serum stimulation. This cell
cycle perturbation by CDK4 disruption was associated with increased
binding of p27 to cyclin E/CDK2 and diminished activation of CDK2
accompanied by impaired Rb phosphorylation. Importantly, fibroblasts
from CDK4/ p27/
embryos displayed partially restored kinetics of the G0-S
transition, indicating the significance of the sequestration of p27 by
CDK4. These results suggest that at least part of CDK4's participation in the rate-limiting mechanism for the G0-S transition
consists of controlling p27 activity.
INTRODUCTION
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
MATERIALS AND METHODS
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
offspring. The genotype of
each mouse was determined by a PCR-based assay or Southern blotting by
using DNA from part of the tail, sampled 14 to 21 days after birth.
/ mice by
keeping each mutant and a wild-type fertile partner together in a cage
and checking daily for the presence of a vaginal plug. Females with
plugs were separated and monitored throughout pregnancy, delivery, and
nursing. Glucosuria was monitored in the morning (9 to 11 a.m.) by
using Chemstrip (Boehringer Mannheim). Each mouse was analyzed for
glucosuria on at least three different days.
-glycerophosphate, 1 mM NaF, 0.1 mM sodium
orthovanadate, 0.2 mM phenylmethylsulfonyl fluoride (PMSF), 20 µg of
aprotinin/ml, 20 µg of leupeptin/ml, 1 µg of pepstatin/ml, 10 µg
of soy bean trypsin inhibitor/ml). Lysates were then clarified by
centrifugation, and protein contents were measured by using the
Bradford reagent (Sigma). CDK2-associated kinase activity was measured
in immunoprecipitates by using histone H1 as a substrate
(57). Fifty micrograms of protein was loaded onto a sodium
dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gel for
quantitative immunoblotting. For the analysis of CDKs in complex with
p27, lysates with 300 µg of protein were immunoprecipitated with 1 µg of affinity-purified anti-p27 antibody (57) or normal
rabbit immunoglobulin G (IgG) as a control. For measurement of p27 in
complex with cyclin E, 600 µg of protein was immunoprecipitated with
2 µg of anti-cyclin E antibody (M-20; Santa Cruz Biotechnology).
Immune complexes were collected by incubation with protein A-agarose
(Pierce) for 1 h at 4°C. After an extensive washing of the
protein A-agarose beads with lysis buffer, immune complexes were
subjected to SDS-PAGE. Immunoblotting was performed by using the
following primary antibodies purchased from Neomarkers and Pharmingen:
CDK2 (clone 2B6 plus 8D4), CDK4 (DCS-31), CDK6 (K6.90 plus K6.83),
cyclin D1 (DCS-6), cyclin D2 (DCS-5.2), cyclin D3 (DCS-28.1), p27
(DCS-72.F6), and Rb (G3-245). The antibody specific for Rb with Ser-780
phosphorylation was obtained from New England Biolabs. Antibody binding
was detected by using peroxidase-conjugated anti-mouse IgG (Pierce) and
the Supersignal chemiluminescence reagent (Pierce). Signals on X-ray films were quantified by using GS-700 Imaging Densitometer and Molecular Analyst software (Bio-Rad).
RESULTS
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
genotype,
and 2 exhibited germ line transmission in the resulting chimeras (Fig.
1b). CDK4+/ mice were overtly normal and
fertile. We then set up intercross mating and cultured fibroblasts from
embryos on day 12.5. No CDK4 protein was detected in
CDK4/ fibroblasts (Fig. 1c and d) by
immunoblotting, indicating that a CDK4-null mutation had been created.
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FIG. 1.
Gene targeting of the CDK4 gene in ES cells
and generation of CDK4-null mice. (a) Targeting replacement vector. A
genomic fragment containing the six exons encoding CDK4 was isolated
from a 129/svj mouse genomic library, and a 6.0-kb
EcoRI-NotI fragment was subcloned into the
pBluescript plasmid vector. The homologous recombination was
constructed by replacing a 2.2-kb MscI fragment of this
plasmid with a neomycin-phosphotransferase gene under the control of
the thymidine kinase promoter for the positive selection. An HSV
thymidine kinase gene under the control of the polyoma enhancer was
then inserted at the 3' side of the 1.2-kb homologous flanking region
for the negative selection. A 1.2-kb BamHI-EcoRI
genomic fragment upstream of the 2.6-kb 5' homologous region was
used as a probe to distinguish the wild-type (wt) and mutant (mut)
alleles. (b) Germ line transmission of the CDK4 mutation.
The gene targeting event was identified by Southern blotting with
BamHI-digested genomic DNAs and the probe shown in panel a.
Germ line transmission was confirmed by the Southern blot with genomic
DNAs of the F1 offspring from crossbreeding of chimeras
with wild-type C57BL/6 mice. An analysis of a representative
F1 litter is shown. (c) PCR genotyping of day 12.5 embryos
obtained from intercross between CDK4-heterozyous mice.
Wild-type (+/+), homozygous ( 
/), and heterozygous (+/) mice were
identified by the presence of PCR products specific for either the wt
or mut allele. (d) Immunoblotting for CDK4 with CDK4 monoclonal
antibody (DCS-31) with extracts of fibroblasts obtained from (+/+),
(/), and (+/) embryos.
Growth retardation in CDK4-deficient mice.
To characterize the
impact of CDK4 deficiency on development and homeostasis in vivo, we
examined CDK4/ mice generated by intercross
breeding of CDK4+/ mice (Fig.
2a). Of 98 mice born from the intercross,
22 (22%) were homozygotes, a figure which is approximately consistent
with the Mendelian rule. However, six (27%) of the homozygotes died by
28 days after birth, while no wild type and only one heterozygote died
during this period, indicating increased postnatal lethality of
CDK4-null mice. Gross autopsy examination did not reveal
major defects related to the lethality, while detailed pathological examinations are still ongoing. CDK4/ mice
were 20% smaller at birth than their littermates with the CDK4+/+ genotype (Fig. 2b). The growth
retardation of the mutants became more obvious during prepuberty,
and the adult homozygotes of both sexes were about 42 to 43% smaller
than wild-type controls. Body weights of
CDK4+/+, CDK4+/, and
CDK4/ males at 7 weeks were 28.8 ± 3.5, 27.3 ± 1.2, and 17.2 ± 1.9 g, while those of
CDK4+/+, CDK4+/,
and CDK4/ females were 20.8 ± 0.9, 20.4 ± 1.8, and 11.9 ± 2.6 g, respectively (means ± standard deviations; n = 7). None of
homozygous mice attained the size of the wild-type mice.
|
Testicular atrophy in CDK4-deficient mice.
Fertility depends
on proliferation and differentiation in the gonads and other
reproductive organs and could be decreased by perturbed cell cycle
regulation (51, 59). We found that fertility was compromised
in both CDK4/ males and females. Only 10%
of male homozygous mutants examined (n = 10) were
fertile, whereas all female mutants (n = 10) were infertile. The testes of 12-week-old CDK4/
mice were remarkably small and displayed dysplastic changes in histological examination (Fig. 2c and d). Cross sections of
seminiferous epithelial tubules in CDK4/
testes had smaller diameters than those in
CDK4+/+ testes and showed reduced numbers of the
spermatogonia/spermatocytes with perturbed layer formation. Mature
spermatids were rarely found in CDK4+/+ testes.
Thus, defective proliferation of gonocytes, together with hypoplastic
supporting structure (i.e., Sertoli cells) of seminiferous epithelia
(34), may contribute to impaired spermatogenesis in mutants.
Perturbed corpus luteum formation in CDK4/
ovaries.
Granulosa cells in the ovary proliferate during
follicular maturation and differentiate into luteal cells following
ovulation (50). Ovaries of 8-week-old
CDK4/ mice exhibited some well-developed
antral follicles and corpora luteum-like structures (Fig. 3b and
d). However, the organization of
granulosa/luteal cells in the corpora luteum-like structures was
significantly disturbed, and aberrant luteinization was often observed
with oocytes trapped in the middle (Fig. 3c). These observations suggest that female infertility in CDK4/
mice may be associated with perturbed regulation of proliferation and
differentiation of granulosa cells.
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Diabetes mellitus in CDK4/ mice.
We found that a majority of adult CDK4/ mice
exhibit glucosuria (Table 1). While no
CDK4/ mice displayed glucosuria at 2 to 3 weeks of age, 60 to 80% of homozygous mutants started exhibiting
glucosuria by 6 to 7 weeks. The rest of mutants did not develop this
diabetic phenotype, at least not during our observations up to 40 weeks. Furthermore, CDK4/ mice had
degenerative changes in islets of Langerhans of the pancreas (Fig.
4). The pancreatic islets are an
endocrine organ secreting insulin, glucagon, and other peptide hormones
(56). Insufficient secretion of insulin from the islets is a
major cause of clinical diabetes mellitus. At 3 weeks of age,
CDK4/ pancreas had fewer islets, many of
which exhibited disorganized cellularity and dying cells with condensed
nuclei (Fig. 4c). In 6-week-old CDK4/ mice
that showed glucosuria, most islets were markedly small, with only a
few cells, as can be seen in Fig. 4d. No sign of inflammation, i.e.,
infiltration of lymphocytes or granulocytes, was observed in
CDK4/ pancreas. There was no significant
change in exocrine acinar cells in pancreas of
CDK4/ mice. This diabetic phenotype with
islet degeneration was observed in both males and females with no
distortion. These data suggest that diabetes mellitus in
CDK4/ mice is associated with degeneration
of islets of Langerhans.
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CDK6 expression in organs of CDK4/
mice.
Since CDK4 and CDK6 possess common biochemical properties as
Rb kinases (2, 35), we examined by immunoblotting whether expression of CDK6 was affected in organs of
CDK4/ mice (Fig.
5). In wild-type mice, CDK6 protein in
the testis was almost undetectable, and that in the pancreas was less
abundant than in the thymus and lung. In
CDK4/ mice, similar patterns of CDK6
expression were detected. Pancreatic expression of CDK6 appeared lower
in CDK4/ mice. Thus, there is apparently no
compensatory increase in CDK6 expression, at least not in these organs
of CDK4/ mice.
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Growth of CDK4/ embryonic
fibroblasts.
As growth retardation and reproductive dysfunction of
CDK4/ mice suggested that cell cycle
progression might be perturbed in CDK4-null cells, we studied growth
properties of fibroblasts from CDK4/ mouse
embryos. Cultures of CDK4/ fibroblasts
were morphologically indistinguishable from those of
CDK4+/+ fibroblasts. The growth curves of
passage 4 CDK4/ fibroblasts in the presence
of 10% FBS were similar to those of CDK4+/+
fibroblasts from the same litters (Fig.
6a), and the distribution of
CDK4/ cells in different phases of the cell
cycle during exponential growth was comparable to that of
CDK4+/+ cells (Fig. 6b). Cells with these two
genotypes displayed contact inhibition at similar cell densities. These
observations were confirmed in experiments by using embryos from three
different litters. Growth of CDK4/
fibroblasts at earlier passages also appeared to be similar to that of
wild-type cells (data not shown). These data suggest that CDK4
disruption has a minimal effect on the rate of continuous proliferation
of embryonic fibroblasts.
|
Delayed cell cycle entry of CDK4/
fibroblasts.
To further determine whether CDK4 has a rate-limiting
role in the transition between quiescence and proliferation, we
examined cell cycle entry of CDK4/ and
CDK4+/+ fibroblasts from quiescence. Passage 4 fibroblasts were starved by 72-h culture in medium supplemented with
0.1% FBS and then stimulated by the addition of 10% FBS. Flow
cytometric analysis of cells stained with anti-BrdU antibody and
propidium iodide demonstrated that by 18 h, wild-type fibroblasts
started to enter the S phase, while most of
CDK4/ cells did not enter S phase until 21 to 24 h (Fig. 7a and b). These
results indicate that the absence of CDK4 significantly delays the
G0-S transition but does not prevent it.
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/
fibroblasts was associated with diminished and delayed expression of
cyclin D1 protein (Fig. 7c), suggesting that growth factor-dependent
signals that regulate the induction of cyclin D1 (7, 27, 28)
are also influenced by CDK4 deficiency. The retinoblastoma protein
(Rb), a well-characterized substrate for cyclin D- and E-dependent
kinases, became hyperphosphorylated just before
CDK4+/+ cells entered S phase, consistent with
previous studies (60). In contrast, Rb remained mostly
hypophosphorylated in CDK4/ cells up to
24 h after serum stimulation, and the total amount of Rb was lower
than that in wild-type cells (Fig. 7c). We further measured
phosphorylation of the serine-780 residue of Rb, which is catalyzed
specifically by cyclin D-dependent kinases (24). While
Ser-780 phosphorylation accumulated significantly during cell cycle
entry of wild-type cells, it was almost undetectable in
serum-stimulated CDK4/ cells up to 24 h, suggesting that the cyclin D-dependent phosphorylation of Rb was
defective. We found that even during exponential growth, the amount of
Rb in CDK4/ cells was about 30 to 50% of
that in CDK4+/+ cells, and phosphorylation was
diminished (data not shown). The expression of CDK6 was increased by
serum stimulation in CDK4/ and
CDK4+/+ cells in similar manners. The expression
of cyclins D2 and D3 did not differ significantly for
CDK4/ and CDK4+/+
cells. In addition, CDK4 was constantly expressed in
CDK4+/+ cells during serum starvation and
restimulation (data not shown). The cellular amount of p27 decreased
somewhat when cells entered the cell cycle for both
CDK4/ and CDK4+/+
cells. We also found that levels of p27 in
CDK4/ cells tended to be 30 to 40% lower
than those in CDK4+/+ cells. CDK2-associated
kinase activity accumulated as wild-type cells entered S phase, whereas
the induction of the kinase activity was substantially diminished and
delayed in CDK4/ cells (Fig. 7d). The
cellular levels of CDK2 protein in CDK4/ and
CDK4+/+ cells were comparable and not affected
by serum starvation and restimulation (data not shown). These data
suggest that CDK4 is part of the rate-limiting mechanism for the
G0-S transition.
Increased binding of p27 to other CDKs in
CDK4/ fibroblasts.
To determine
whether alterations in p27-CDK interactions are involved in the
delayed cell cycle entry of CDK4/ cells, we
measured the amounts of CDKs bound to p27 in cells 18 h after
serum stimulation by immunoprecipitation, followed by immunoblotting
(Fig. 8a). Wild-type cells showed a
substantial amount of CDK4 in complex with p27, while no CDK4 was
detected in complex with p27 in CDK4/ cells.
We detected increases in the amounts of CDK2 and CDK6 bound to p27 in
serum-stimulated CDK4/ cells, by 2.0- and
3.4-fold, respectively, compared with those in wild-type cells. In
particular, two forms of CDK2 with different electrophoretic migrations
were detected in the p27-associated complex from CDK4-null cells,
whereas only the faster-migrating form of CDK2 bound to p27 in
wild-type cells. Previous studies suggested that the faster-migrating
form of CDK2 is phosphorylated on the Thr-160 residue by CDK-activating
kinase (CAK) (17). These results suggest that p27 in
CDK4-null cells may bind not only CAK-phosphorylated cyclin E-CDK2
complexes but also newly associated complexes that have not been
phosphorylated by CAK. To further determine whether a larger amount of
p27 is associated with cyclin E-CDK2 in serum-stimulated
CDK4/ fibroblasts than in wild-type
cells, we measured the amounts of p27 in the cyclin E
immunoprecipitates from cell lysates prepared 18 h after serum
stimulation. The amount of p27 associated with cyclin E was 2.4-fold
greater in CDK4/ cells than in
CDK4+/+ cells, although similar amounts of
cyclin E are expressed (Fig. 8b and c). These results suggest that the
elimination of CDK4 results in the association of more p27 protein with
cyclin E-CDK2 and cyclin D-CDK6 complexes.
|
Restored kinetics of the G0-S transition in
CDK4/ p27/
fibroblasts.
To further determine whether enhanced activity of p27
to bind cyclin E-CDK2 plays a significant role in the delayed cell
cycle entry of CDK4-null fibroblasts, we examined fibroblasts from
mouse embryos lacking both CDK4 and p27, which we generated by
crossbreeding between the CDK4- and p27-deficient mouse strains
(25). In the presence of 10% FBS, all cell types examined,
such as CDK4/ p27+/+,
CDK4+/+ p27/,
CDK4/ p27/, and
CDK4+/+ p27/,
displayed similar patterns of cell cycle distribution, according to the
double staining with BrdU and propidium iodide (data not shown). After
serum starvation and restimulation, CDK4/
p27/ cells, which lacked both CDK4 and p27,
entered S phase with only a modest delay compared to the time to entry
of wild-type cells (Fig. 9). This
contrasted sharply with the marked delay of
CDK4/ p27+/+ cells.
In addition, CDK4+/+
p27/ cells entered S phase with similar or
slightly accelerated kinetics compared with those of wild-type cells.
These observations that the elimination of p27 substantially restored
the kinetics of cell cycle entry in CDK4-null cells suggest that the
rate-limiting function of CDK4 for the G0-S transition
depends at least partly on its activity in sequestering p27.
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DISCUSSION |
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Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
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In this study, we demonstrated that
CDK4/ mice survive embryogenesis, suggesting
that CDK4 is not essential for mouse development. Furthermore, examination of CDK4/
fibroblasts suggested that CDK4 is dispensable during continuous proliferation. However, our analysis with quiescent
CDK4/ fibroblasts indicated that CDK4 plays
a rate-limiting role when quiescent cells enter the cell cycle. Growth
retardation, reproductive dysfunction, and degeneration of pancreatic
islets in CDK4/ mice further suggest that
CDK4 plays a critical role in in vivo regulation of cell cycle
progression, the lack of which other CDKs cannot completely compensate for.
The dwarfism-like phenotype of CDK4-null mice is reminiscent
of those in cyclin D1-deficient mice (13, 55) and transgenic mice with high copy numbers of the Rb gene (4). It also
presents an image opposite to that of the gigantism-like phenotypes of mice deficient in the CDK inhibitor p27 (25) and mice
lacking p18INK4c, an inhibitor of CDK4 and CDK6 (14,
16, 38). These observations suggest that the genetic pathway
involving p27, p18, cyclin D1, CDK4, and Rb may be important for
regulation of animal growth (46). Perturbed G1
progression in serum-stimulated CDK4/
embryonic fibroblasts further implies that growth retardation of
CDK4/ mice is associated with defective cell
cycle regulation during development. However, it is also possible that
the dwarfism in CDK4/ mice is due to another
problem, e.g., a neurological or an endocrine disorder.
The gonads are highly proliferative organs. In the adult testis, germ
cells continuously proliferate and differentiate into spermatids in
response to hormonal signals. Disturbed control of proliferation in the
gonads could lead to reduced or abrogated fertility. We have shown that
CDK4 deficiency leads to reproductive dysfunction in both males and
females. The testicular atrophy in CDK4/
males showed some similarity to that in mice lacking E2F-1
(15, 62). Phosphorylation of Rb by cyclin D-CDK4 activates
the transcriptional activity of E2F-1 by releasing E2F-1 from
sequestration (37). Thus, this genetic pathway seems to be
critical for proper regulation of spermatogenesis.
In contrast with proliferating spermatogonia in the testis, oocytes in
the adult ovary are arrested in meiosis, while somatic granulosa cells
in the follicle proliferate and differentiate in response to
gonadotropins (50). Maintenance of the oocyte function
depends on interactions between oocytes and granulosa cells via
cell-cell contact and paracrine factors. Furthermore, upon ovulation,
granulosa cells differentiate into luteal cells, which secrete steroid
and peptide hormones required for the maintenance of pregnancy.
CDK4/ females were infertile, and their
ovaries exhibited disturbed cellularity in corpora luteum and
apparently abnormal luteinization. These morphological changes in
CDK4/ ovaries looked different from those in
infertile cyclin D2/ mice (51,
54). cyclin D2/ ovaries had only small
follicles and are defective in FSH-dependent proliferation of granulosa
cells. In contrast, the absence of CDK4 seems to allow granulosa
cells to proliferate to form large follicles, although the kinetics of
differentiation may be disturbed. This difference between
cyclin D2/ and
CDK4/ ovaries implies that in the
absence of CDK4, cyclin D2 may activate other CDKs to somehow
promote granulosa cell proliferation. Female mice lacking p27 are also
infertile in association with hyperproliferation of
granulosa cells during luteal differentiation (25, 59). These studies recapitulate the importance of the pathway involving cyclin D2, CDK4, and p27 in the homeostasis of the
proliferation and differentiation of granulosa cells.
We have found that a majority of CDK4/ mice
develop diabetes mellitus, associated with degenerative changes in
pancreatic islets. This spontaneous development of nonobese diabetes
resembles that in NOD mice or BB rats, which are animal models of
autoimmune type I diabetes (8, 33). However,
CDK4/ pancreas displayed no sign of
insulitis, the characteristic inflammation of islets due to
autoimmunity. The marked decrease in cell numbers of
CDK4/ pancreatic islets and the presence of
apoptotic cells suggest that CDK4 plays a critical role for the
postnatal proliferation (and possibly for the maintenance) of these
endocrine islet cells. The loss of islets, and especially of
insulin-secreting B cells, leads to the development of diabetes
(56). It is presently unclear why approximately 30% of
CDK4-null mice do not develop diabetes. Although diabetes could
affect postnatal growth, all CDK4/ mice
display similar extents of growth retardation whether or not they
develop symptomatic diabetes. In addition, postnatal death often
observed by 4 weeks of age does not seem to be related to diabetes,
since no CDK4/ mice developed glucosuria
until 5 to 6 weeks. We are currently investigating the mechanism of the
incomplete penetrance of diabetes and its relationship to other
phenotypes of these mutant animals.
The delayed cell cycle entry of CDK4/
fibroblasts with impaired Rb phosphorylation indicates that CDK4
participates in the rate-limiting mechanism for the G0-S
transition. Diminished phosphorylation of Ser-780 of Rb, a specific
target of cyclin D-dependent kinases (24), further implies
that in fibroblasts, CDK4 plays a central role in the initiation of Rb
phosphorylation. Although CDK6 is bound to D-type cyclins, Rb kinase
activity detected in CDK6 immunoprecipitates is very weak in both
wild-type and CDK4/ fibroblasts
(18a). The question of whether CDK6 is essential for
proliferation without CDK4 awaits future experiments to inactivate CDK6
in CDK4/ cells by gene targeting or other methods.
Our data also recapitulate the significance of CDK4-p27 interaction for
the control of cyclin E-CDK2 activation. A larger amount of p27 that is
free from sequestration could set a higher inhibitory threshold for the
cyclin E-CDK2 activity. Therefore, p27 may act as an intermediate
coordinator of CDK4 and CDK2 activation. The partial restoration of the
kinetics of the G0-S transition in
CDK4/ p27/
fibroblasts supports the hypothesis that CDK4 functions as an upstream
regulator of p27, although the enhanced proliferation of
CDK4/ p27/ cells
may involve other regulatory mechanism(s) independent of the CDK4-p27
interaction, such as redistribution of other CDK inhibitors and
modifications of CDK proteins. The mechanism of this enhanced S-phase
entry is complex, since elevated CDK2 activity by p27 elimination might
also compensate for the absence of CDK4, especially in Rb
phosphorylation. We have observed that in serum-stimulated CDK4/ p27/ cells,
the amounts of hyperphosphorylated Rb are slightly increased compared
with those in CDK4/
p27+/+ cells (data not shown).
In proliferating cells, a majority of p27 molecules are in complex with
cyclin D-dependent kinases (44), which does not necessarily
inhibit the kinase activity (5, 57). In contrast, cyclin
E-CDK2 and cyclin A-CDK2 appear to be inhibited whenever they bind to
p27 (5, 57). Moreover, studies with inducible expression of
p27 or in vitro-purified proteins have demonstrated that the amount of
p27 required for inhibition of cyclin D-CDK4 is much larger than that
required for the inhibition of cyclin A-CDK2 (5, 43). Our
study together with these other studies suggests the significance of
the p27-regulatory action of CDK4 in the G0-S transition.
The p27 reservoir function of CDK4 may allow multiple modes of control
of G1-CDK activity in response to various extracellular
signals. For instance, transforming growth factor decreases the
expression of CDK4 (12) and induces the CDK4-specific
inhibitor p15INK4b (18, 49). These changes will
disrupt the cyclin D-CDK4-p27 complex, leading to the inhibition of
cyclin E-CDK2 and cyclin A-CDK2. Growth factor deprivation,
differentiation, contact inhibition, or loss of anchorage will
also decrease the expression of cyclin D and/or CDK4 (23, 26, 32,
44, 63), resulting in the mobilization of p27 to the CDK2
complexes. In contrast, when cells enter the cell cycle from
quiescence, mitogenic signals facilitate complex formation of
cyclin D-CDK4 (7), which will sequester p27 and allow the
timely activation of cyclin E-CDK2.
Growth retardation and reproductive dysfunction in CDK4-null mice present an opposite image to the phenotype of mice deficient in p27, such as gigantism and gonadal hyperplasia (14, 25, 38). These observations imply that p27 and CDK4 genetically counteract to regulate animal growth and reproductive function, which may depend on the stoichiometric interaction between these two molecules. Interestingly, 7-week-old mice deficient in both p27 and CDK4 (n = 3) are 18 to 33% smaller than wild-type litter mice, whereas CDK4-null mice with intact p27 are 35 to 57% smaller than wild-type controls (24a). CDK4- and p27-null mice provide unique models in which we can further investigate interactions of cell cycle-regulatory proteins and their roles in development and oncogenesis.
| |
ACKNOWLEDGMENTS |
|---|
We thank Lida Aris and Angel Alvarez for technical assistance, Vera C. Soares for blastocyst injections, Rex Hess and Geula Gibori for comments on morphology of testes and ovaries, respectively, and William T. Beck for helpful suggestions.
This work was supported by funds provided to H.K. by the American Cancer Society, Illinois Division (no. 98-41), the Campus Research Board of the University of Illinois, and the Cancer Center of University of Illinois at Chicago and by funds provided to A.K. from the National Institutes of Health (GM52597) and the Pew Foundation. T.T. was supported by Osaka University.
| |
FOOTNOTES |
|---|
* Corresponding author. Mailing address: 900 S. Ashland Ave., MC 669, Chicago, IL 60607. Phone: (312) 355-1601. Fax: (312) 413-0353. E-mail: kiyokawa{at}uic.edu.
Present address: Department of Obstetrics and Gynecology, Osaka
University Medical School, Osaka 565, Japan.
| |
REFERENCES |
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Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
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| 1. |
Ando, K.,
F. Ajchenbaum-Cymbalista, and J. D. Griffin.
1993.
Regulation of G1/S transition by cyclins D2 and D3 in hematopoietic cells.
Proc. Natl. Acad. Sci. USA
90:9571-9575 |
| 2. | Bates, S., L. Bonetta, D. MacAllan, D. Parry, A. Holder, C. Dickson, and G. Peters. 1994. CDK6 (PLSTIRE) and CDK4 (PSK-J3) are a distinct subset of the cyclin-dependent kinases that associate with cyclin D1. Oncogene 9:71-79[Medline]. |
| 3. |
Beijersbergen, R. L.,
L. Carlee,
R. M. Kerkhoven, and R. Bernards.
1995.
Regulation of the retinoblastoma protein-related p107 by G1 cyclin complexes.
Genes Dev.
9:1340-1353 |
| 4. |
Bignon, Y. J.,
Y. Chen,
C. Y. Chang,
D. J. Riley,
J. J. Windle,
P. L. Mellon, and W. H. Lee.
1993.
Expression of a retinoblastoma transgene results in dwarf mice.
Genes Dev.
7:1654-1662 |
| 5. |
Blain, S. W.,
E. Montalvo, and J. Massague.
1997.
Differential interaction of the cyclin-dependent kinase (Cdk) inhibitor p27Kip1 with cyclin A-Cdk2 and cyclin D2-Cdk4.
J. Biol. Chem.
272:25863-25872 |
| 6. |
Casaccia-Bonnefil, P.,
R. Tikoo,
H. Kiyokawa,
V. J. Friedrich,
M. V. Chao, and A. Koff.
1997.
Oligodendrocyte precursor differentiation is perturbed in the absence of the cyclin-dependent kinase inhibitor p27Kip1.
Genes Dev.
11:2335-2346 |
| 7. |
Cheng, M.,
V. Sexl,
C. J. Sherr, and M. F. Roussel.
1998.
Assembly of cyclin D-dependent kinase and titration of p27Kip1 regulated by mitogen-activated protein kinase kinase (MEK1).
Proc. Natl. Acad. Sci. USA
95:1091-1096 |
| 8. | Cheta, D. 1998. Animal models of type I (insulin-dependent) diabetes mellitus. J. Pediatr. Endocrinol. Metab. 11:11-19[Medline]. |
| 9. |
Dong, F.,
W. D. J. Cress,
D. Agrawal, and W. J. Pledger.
1998.
The role of cyclin D3-dependent kinase in the phosphorylation of p130 in mouse BALB/c 3T3 fibroblasts.
J. Biol. Chem.
273:6190-6195 |
| 10. | Dowdy, S. F., P. W. Hinds, K. Louie, S. I. Reed, A. Arnold, and R. A. Weinberg. 1993. Physical interaction of the retinoblastoma protein with human D cyclins. Cell 73:499-511[Medline]. |
| 11. | Ewen, M. E., H. K. Sluss, C. J. Sherr, H. Matsushime, J. Kato, and D. M. Livingston. 1993. Functional interactions of the retinoblastoma protein with mammalian D-type cyclins. Cell 73:487-497[Medline]. |
| 12. | Ewen, M. E., H. K. Sluss, L. L. Whitehouse, and D. M. Livingston. 1993. TGF beta inhibition of Cdk4 synthesis is linked to cell cycle arrest. Cell 74:1009-1020[Medline]. |
| 13. |
Fantl, V.,
G. Stamp,
A. Andrews,
I. Rosewell, and C. Dickson.
1995.
Mice lacking cyclin D1 are small and show defects in eye and mammary gland development.
Genes Dev.
9:2364-2372 |
| 14. | Fero, M. L., M. Rivkin, M. Tasch, P. Porter, C. E. Carow, E. Firpo, K. Polyak, L. H. Tsai, V. Broudy, R. M. Perlmutter, K. Kaushansky, and J. M. Roberts. 1996. A syndrome of multiorgan hyperplasia with features of gigantism, tumorigenesis, and female sterility in p27(Kip1)-deficient mice. Cell 85:733-744[Medline]. |
| 15. | Field, S. J., F. Y. Tsai, F. Kuo, A. M. Zubiaga, W. G. J. Kaelin, D. M. Livingston, S. H. Orkin, and M. E. Greenberg. 1996. E2F-1 functions in mice to promote apoptosis and suppress proliferation. Cell 85:549-561[Medline]. |
| 16. |
Franklin, D. S.,
V. L. Godfrey,
H. Lee,
G. I. Kovalev,
R. Schoonhoven,
S. Chen-Kiang,
L. Su, and Y. Xiong.
1998.
CDK inhibitors p18(INK4c) and p27(Kip1) mediate two separate pathways to collaboratively suppress pituitary tumorigenesis.
Genes Dev.
12:2899-2911 |
| 17. | Gu, Y., J. Rosenblatt, and D. O. Morgan. 1992. Cell cycle regulation of CDK2 activity by phosphorylation of Thr160 and Tyr15. EMBO J. 11:3995-4005[Medline]. |
| 18. | Hannon, G. J., and D. Beach. 1994. p15INK4B is a potential effector of TGF-beta-induced cell cycle arrest. Nature 371:257-261[Medline]. |
| 18a. | Hesabi, B., T. Tsutsui, and H. Kiyokawa. Unpublished observations. |
| 19. | Hinds, P. W., S. Mittnacht, V. Dulic, A. Arnold, S. I. Reed, and R. A. Weinberg. 1992. Regulation of retinoblastoma protein functions by ectopic expression of human cyclins. Cell 70:993-1006[Medline]. |
| 20. | Hogan, B., R. Beddington, F. Costantini, and E. Lacy. 1994. Manipulating the mouse embryo, 2nd ed. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. |
| 21. | Hunter, T., and J. Pines. 1994. Cyclins and cancer. II. Cyclin D and CDK inhibitors come of age. Cell 79:573-582[Medline]. |
| 22. |
Kato, J.,
H. Matsushime,
S. W. Hiebert,
M. E. Ewen, and C. J. Sherr.
1993.
Direct binding of cyclin D to the retinoblastoma gene product (pRb) and pRb phosphorylation by the cyclin D-dependent kinase CDK4.
Genes Dev.
7:331-342 |
| 23. |
Kato, J. Y., and C. J. Sherr.
1993.
Inhibition of granulocyte differentiation by G1 cyclins D2 and D3 but not D1.
Proc. Natl. Acad. Sci. USA
90:11513-11517 |
| 24. | Kitagawa, M., H. Higashi, H. K. Jung, I. Suzuki-Takahashi, M. Ikeda, K. Tamai, J. Kato, K. Segawa, E. Yoshida, S. Nishimura, and Y. Taya. 1996. The consensus motif for phosphorylation by cyclin D1-Cdk4 is different from that for phosphorylation by cyclin A/E-Cdk2. EMBO J. 15:7060-7069[Medline]. |
| 24a. | Kiyokawa, H. Unpublished observations. |
| 25. | Kiyokawa, H., R. D. Kineman, K. O. Manova-Todorova, V. C. Soares, E. S. Hoffman, M. Ono, D. Khanam, A. C. Hayday, L. A. Frohman, and A. Koff. 1996. Enhanced growth of mice lacking the cyclin-dependent kinase inhibitor function of p27(Kip1). Cell 85:721-732[Medline]. |
| 26. |
Kiyokawa, H.,
V. M. Richon,
R. A. Rifkind, and P. A. Marks.
1994.
Suppression of cyclin-dependent kinase 4 during induced differentiation of erythroleukemia cells.
Mol. Cell. Biol.
14:7195-7203 |
| 27. |
Ladha, M. H.,
K. Y. Lee,
T. M. Upton,
M. F. Reed, and M. E. Ewen.
1998.
Regulation of exit from quiescence by p27 and cyclin D1-CDK4.
Mol. Cell. Biol.
18:6605-6615 |
| 28. |
Lavoie, J. N.,
G. L'Allemain,
A. Brunet,
R. Muller, and J. Pouyssegur.
1996.
Cyclin D1 expression is regulated positively by the p42/p44MAPK and negatively by the p38/HOGMAPK pathway.
J. Biol. Chem.
271:20608-20616 |
| 29. |
Lundberg, A. S., and R. A. Weinberg.
1998.
Functional inactivation of the retinoblastoma protein requires sequential modification by at least two distinct cyclin-cdk complexes.
Mol. Cell. Biol.
18:753-761 |
| 30. | Luo, Y., S. O. Marx, H. Kiyokawa, A. Koff, J. Massague, and A. R. Marks. 1996. Rapamycin resistance tied to defective regulation of p27Kip1. Mol. Cell. Biol. 16:6744-6751[Abstract]. |
| 31. | Matsushime, H., M. E. Ewen, D. K. Strom, J. Y. Kato, S. K. Hanks, M. F. Roussel, and C. J. Sherr. 1992. Identification and properties of an atypical catalytic subunit (p34PSK-J3/cdk4) for mammalian D type G1 cyclins. Cell 71:323-334[Medline]. |
| 32. | Matsushime, H., M. F. Roussel, R. A. Ashmun, and C. J. Sherr. 1991. Colony-stimulating factor 1 regulates novel cyclins during the G1 phase of the cell cycle. Cell 65:701-713[Medline]. |
| 33. | McDuffie, M. 1998. Genetics of autoimmune diabetes in animal models. Curr. Opin. Immunol. 10:704-709[Medline]. |
| 34. | McLaren, A. 1998. Gonad development: assembling the mammalian testis. Curr. Biol. 8:R175-R177[Medline]. |
| 35. |
Meyerson, M., and E. Harlow.
1994.
Identification of G1 kinase activity for cdk6, a novel cyclin D partner.
Mol. Cell. Biol.
14:2077-2086 |
| 36. |
Missero, C.,
F. Di Cunto,
H. Kiyokawa,
A. Koff, and G. P. Dotto.
1996.
The absence of p21Cip1/WAF1 alters keratinocyte growth and differentiation and promotes ras-tumor progression.
Genes Dev.
10:3065-3075 |
| 37. | Mulligan, G., and T. Jacks. 1998. The retinoblastoma gene family: cousins with overlapping interests. Trends Genet. 14:223-229[Medline]. |
| 38. | Nakayama, K., N. Ishida, M. Shirane, A. Inomata, T. Inoue, N. Shishido, I. Horii, D. Y. Loh, and K. Nakayama. 1996. Mice lacking p27(Kip1) display increased body size, multiple organ hyperplasia, retinal dysplasia, and pituitary tumors. Cell 85:707-720[Medline]. |
| 39. | Nevins, J. R., G. Leone, J. DeGregori, and L. Jakoi. 1997. Role of the Rb/E2F pathway in cell growth control. J. Cell. Physiol. 173:233-236[Medline]. |
| 40. |
Ohtsubo, M., and J. M. Roberts.
1993.
Cyclin-dependent regulation of G1 in mammalian fibroblasts.
Science
259:1908-1912 |
| 41. | Pagano, M., R. Pepperkok, F. Verde, W. Ansorge, and G. Draetta. 1992. Cyclin A is required at two points in the human cell cycle. EMBO J. 11:961-971[Medline]. |
| 42. |
Pardee, A. B.
1989.
G1 events and regulation of cell proliferation.
Science
246:603-608 |
| 43. | Polyak, K., M. H. Lee, H. Erdjument-Bromage, A. Koff, J. M. Roberts, P. Tempst, and J. Massague. 1994. Cloning of p27Kip1, a cyclin-dependent kinase inhibitor and a potential mediator of extracellular antimitogenic signals. Cell 78:59-66[Medline]. |
| 44. | Poon, R. Y., H. Toyoshima, and T. Hunter. 1995. Redistribution of the CDK inhibitor p27 between different cyclin. CDK complexes in the mouse fibroblast cell cycle and in cells arrested with lovastatin or ultraviolet irradiation. Mol. Biol. Cell 6:1197-1213[Abstract]. |
| 45. |
Quelle, D. E.,
R. A. Ashmun,
S. A. Shurtleff,
J. Y. Kato,
D. Bar-Sagi,
M. F. Roussel, and C. J. Sherr.
1993.
Overexpression of mouse D-type cyclins accelerates G1 phase in rodent fibroblasts.
Genes Dev.
7:1559-1571 |
| 46. | Raff, M. C. 1996. Size control: the regulation of cell numbers in animal development. Cell 86:173-175[Medline]. |
| 47. | Ramirez-Solis, R., and A. Bradley. 1994. Advances in the use of embryonic stem cell technology. Curr. Opin. Biotechnol. 5:528-533[Medline]. |
| 48. | Reed, S. I. 1997. Control of the G1/S transition. Cancer Surv. 29:7-23[Medline]. |
| 49. |
Reynisdottir, I.,
K. Polyak,
A. Iavarone, and J. Massague.
1995.
Kip/Cip and Ink4 Cdk inhibitors cooperate to induce cell cycle arrest in response to TGF-beta.
Genes Dev.
9:1831-1845 |
| 50. | Richards, J. S., S. L. Fitzpatrick, J. W. Clemens, J. K. Morris, T. Alliston, and J. Sirois. 1995. Ovarian cell differentiation: a cascade of multiple hormones, cellular signals, and regulated genes. Recent Prog. Horm. Res. 50:223-254. |
| 51. |
Robker, R. L., and J. S. Richards.
1998.
Hormone-induced proliferation and differentiation of granulosa cells: a coordinated balance of the cell cycle regulators cyclin D2 and p27Kip1.
Mol. Endocrinol.
12:924-940 |
| 52. | Sherr, C. J. 1994. G1 phase progression: cycling on cue. Cell 79:551-555[Medline]. |
| 53. |
Sherr, C. J., and J. M. Roberts.
1995.
Inhibitors of mammalian G1 cyclin-dependent kinases.
Genes Dev.
9:1149-1163 |
| 54. | Sicinski, P., J. L. Donaher, Y. Geng, S. B. Parker, H. Gardner, M. Y. Park, R. L. Robker, J. S. Richards, L. K. McGinnis, J. D. Biggers, J. J. Eppig, R. T. Bronson, S. J. Elledge, and R. A. Weinberg. 1996. Cyclin D2 is an FSH-responsive gene involved in gonadal cell proliferation and oncogenesis. Nature 384:470-474[Medline]. |
| 55. | Sicinski, P., J. L. Donaher, S. B. Parker, T. Li, A. Fazeli, H. Gardner, S. Z. Haslam, R. T. Bronson, S. J. Elledge, and R. A. Weinberg. 1995. Cyclin D1 provides a link between development and oncogenesis in the retina and breast. Cell 82:621-630[Medline]. |
| 56. | Slack, J. M. 1995. Developmental biology of the pancreas. Development 121:1569-1580[Abstract]. |
| 57. | Soos, T. J., H. Kiyokawa, J. S. Yan, M. S. Rubin, A. Giordano, A. DeBlasio, S. Bottega, B. Wong, J. Mendelsohn, and A. Koff. 1996. Formation of p27-CDK complexes during the human mitotic cell cycle. Cell Growth Differ. 7:135-146[Abstract]. |
| 58. |
Swiatek, P. J., and T. Gridley.
1993.
Perinatal lethality and defects in hindbrain development in mice homozygous for a targeted mutation of the zinc finger gene Krox20.
Genes Dev.
7:2071-2084 |
| 59. |
Tong, W.,
H. Kiyokawa,
T. J. Soos,
M. Park,
V. C. Soares,
K. O. Manova-Todorova,
J. W. Pollard, and A. Koff.
1998.
The absence of p27Kip1, an inhibitor of G1 cyclin-dependent kinases, uncouples differentiation and growth arrest during the granulosa luteal transition.
Cell Growth Differ.
9:787-794[Abstract].
|
| 60. | Weinberg, R. A. 1995. The retinoblastoma protein and cell cycle control. Cell 81:323-330[Medline]. |
| 61. |
Xiao, Z. X.,
D. Ginsberg,
M. Ewen, and D. M. Livingston.
1996.
Regulation of the retinoblastoma protein-related protein p107 by G1 cyclin-associated kinases.
Proc. Natl. Acad. Sci. USA
93:4633-4637 |
| 62. | Yamasaki, L., T. Jacks, R. Bronson, E. Goillot, E. Harlow, and N. J. Dyson. 1996. Tumor induction and tissue atrophy in mice lacking E2F-1. Cell 85:537-548[Medline]. |
| 63. |
Zhu, X.,
M. Ohtsubo,
R. M. Bohmer,
J. M. Roberts, and R. K. Assoian.
1996.
Adhesion-dependent cell cycle progression linked to the expression of cyclin D1, activation of cyclin E-cdk2, and phosphorylation of the retinoblastoma protein.
J. Cell Biol.
133:391-403 |
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67: 10564-10572
[Abstract] [Full Text] -
Macias, E., Kim, Y., Miliani de Marval, P. L., Klein-Szanto, A., Rodriguez-Puebla, M. L.
(2007). Cdk2 Deficiency Decreases ras/CDK4-Dependent Malignant Progression, but Not myc-Induced Tumorigenesis. Cancer Res.
67: 9713-9720
[Abstract] [Full Text] -
Wang, B., Omar, A., Angelovska, T., Drobic, V., Rattan, S. G., Jones, S. C., Dixon, I. M. C.
(2007). Regulation of collagen synthesis by inhibitory Smad7 in cardiac myofibroblasts. Am. J. Physiol. Heart Circ. Physiol.
293: H1282-H1290
[Abstract] [Full Text] -
Ray, D., Terao, Y., Nimbalkar, D., Hirai, H., Osmundson, E. C., Zou, X., Franks, R., Christov, K., Kiyokawa, H.
(2007). Hemizygous Disruption of Cdc25A Inhibits Cellular Transformation and Mammary Tumorigenesis in Mice. Cancer Res.
67: 6605-6611
[Abstract] [Full Text] -
Alonso, L. C., Yokoe, T., Zhang, P., Scott, D. K., Kim, S. K., O'Donnell, C. P., Garcia-Ocana, A.
(2007). Glucose Infusion in Mice: A New Model to Induce {beta}-Cell Replication. Diabetes
56: 1792-1801
[Abstract] [Full Text] -
Muntean, A. G., Pang, L., Poncz, M., Dowdy, S. F., Blobel, G. A., Crispino, J. D.
(2007). Cyclin D-Cdk4 is regulated by GATA-1 and required for megakaryocyte growth and polyploidization. Blood
109: 5199-5207
[Abstract] [Full Text] -
Scott, L. J., Mohlke, K. L., Bonnycastle, L. L., Willer, C. J., Li, Y., Duren, W. L., Erdos, M. R., Stringham, H. M., Chines, P. S., Jackson, A. U., Prokunina-Olsson, L., Ding, C.-J., Swift, A. J., Narisu, N., Hu, T., Pruim, R., Xiao, R., Li, X.-Y., Conneely, K. N., Riebow, N. L., Sprau, A. G., Tong, M., White, P. P., Hetrick, K. N., Barnhart, M. W., Bark, C. W., Goldstein, J. L., Watkins, L., Xiang, F., Saramies, J., Buchanan, T. A., Watanabe, R. M., Valle, T. T., Kinnunen, L., Abecasis, G. R., Pugh, E. W., Doheny, K. F., Bergman, R. N., Tuomilehto, J., Collins, F. S., Boehnke, M.
(2007). A Genome-Wide Association Study of Type 2 Diabetes in Finns Detects Multiple Susceptibility Variants. Science
316: 1341-1345
[Abstract] [Full Text] -
Ramsey, M. R., Krishnamurthy, J., Pei, X.-H., Torrice, C., Lin, W., Carrasco, D. R., Ligon, K. L., Xiong, Y., Sharpless, N. E.
(2007). Expression of p16Ink4a Compensates for p18Ink4c Loss in Cyclin-Dependent Kinase 4/6-Dependent Tumors and Tissues. Cancer Res.
67: 4732-4741
[Abstract] [Full Text] -
Ray, D., Terao, Y., Fuhrken, P. G., Ma, Z.-Q., DeMayo, F. J., Christov, K., Heerema, N. A., Franks, R., Tsai, S. Y., Papoutsakis, E. T., Kiyokawa, H.
(2007). Deregulated CDC25A Expression Promotes Mammary Tumorigenesis with Genomic Instability. Cancer Res.
67: 984-991
[Abstract] [Full Text] -
Stocco, C., Telleria, C., Gibori, G.
(2007). The Molecular Control of Corpus Luteum Formation, Function, and Regression. Endocr. Rev.
28: 117-149
[Abstract] [Full Text] -
Vasavada, R. C., Cozar-Castellano, I., Sipula, D., Stewart, A. F.
(2007). Tissue-Specific Deletion of the Retinoblastoma Protein in the Pancreatic {beta}-Cell Has Limited Effects on {beta}-Cell Replication, Mass, and Function. Diabetes
56: 57-64
[Abstract] [Full Text] -
Cozar-Castellano, I., Haught, M., Stewart, A. F.
(2006). The Cell Cycle Inhibitory Protein p21cip Is Not Essential for Maintaining {beta}-Cell Cycle Arrest or {beta}-Cell Function In Vivo. Diabetes
55: 3271-3278
[Abstract] [Full Text] -
Rachdi, L., Balcazar, N., Elghazi, L., Barker, D. J., Krits, I., Kiyokawa, H., Bernal-Mizrachi, E.
(2006). Differential Effects of p27 in Regulation of {beta}-Cell Mass During Development, Neonatal Period, and Adult Life. Diabetes
55: 3520-3528
[Abstract] [Full Text] -
Cohen, P. E., Pollack, S. E., Pollard, J. W.
(2006). Genetic Analysis of Chromosome Pairing, Recombination, and Cell Cycle Control during First Meiotic Prophase in Mammals. Endocr. Rev.
27: 398-426
[Abstract] [Full Text] -
Cozar-Castellano, I., Fiaschi-Taesch, N., Bigatel, T. A., Takane, K. K., Garcia-Ocana, A., Vasavada, R., Stewart, A. F.
(2006). Molecular Control of Cell Cycle Progression in the Pancreatic {beta}-Cell. Endocr. Rev.
27: 356-370
[Abstract] [Full Text] -
Fatrai, S., Elghazi, L., Balcazar, N., Cras-Meneur, C., Krits, I., Kiyokawa, H., Bernal-Mizrachi, E.
(2006). Akt Induces {beta}-Cell Proliferation by Regulating Cyclin D1, Cyclin D2, and p21 Levels and Cyclin-Dependent Kinase-4 Activity. Diabetes
55: 318-325
[Abstract] [Full Text] -
Cozar-Castellano, I., Weinstock, M., Haught, M., Velazquez-Garcia, S., Sipula, D., Stewart, A. F.
(2006). Evaluation of {beta}-Cell Replication in Mice Transgenic for Hepatocyte Growth Factor and Placental Lactogen: Comprehensive Characterization of the G1/S Regulatory Proteins Reveals Unique Involvement of p21cip. Diabetes
55: 70-77
[Abstract] [Full Text] -
Loveland, K. L., Hogarth, C., Szczepny, A., Prabhu, S. M., Jans, D. A.
(2006). Expression of Nuclear Transport Importins beta 1 and beta 3 Is Regulated During Rodent Spermatogenesis. Biol. Reprod.
74: 67-74
[Abstract] [Full Text] -
Chesnokova, V., Kovacs, K., Castro, A.-V., Zonis, S., Melmed, S.
(2005). Pituitary Hypoplasia in Pttg-/- Mice Is Protective for Rb+/- Pituitary Tumorigenesis. Mol. Endocrinol.
19: 2371-2379
[Abstract] [Full Text] -
Kushner, J. A., Ciemerych, M. A., Sicinska, E., Wartschow, L. M., Teta, M., Long, S. Y., Sicinski, P., White, M. F.
(2005). Cyclins D2 and D1 Are Essential for Postnatal Pancreatic {beta}-Cell Growth. Mol. Cell. Biol.
25: 3752-3762
[Abstract] [Full Text] -
Ray, D., Terao, Y., Nimbalkar, D., Chu, L.-H., Donzelli, M., Tsutsui, T., Zou, X., Ghosh, A. K., Varga, J., Draetta, G. F., Kiyokawa, H.
(2005). Transforming Growth Factor {beta} Facilitates {beta}-TrCP-Mediated Degradation of Cdc25A in a Smad3-Dependent Manner. Mol. Cell. Biol.
25: 3338-3347
[Abstract] [Full Text] -
Kaldis, P.
(2005). The N-terminal Peptide of the Kaposi's Sarcoma-associated Herpesvirus (KSHV)-cyclin Determines Substrate Specificity. J. Biol. Chem.
280: 11165-11174
[Abstract] [Full Text] -
Zhang, X., Gaspard, J. P., Mizukami, Y., Li, J., Graeme-Cook, F., Chung, D. C.
(2005). Overexpression of Cyclin D1 in Pancreatic {beta}-Cells In Vivo Results in Islet Hyperplasia Without Hypoglycemia. Diabetes
54: 712-719
[Abstract] [Full Text] -
Wolfraim, L. A., Letterio, J. J.
(2005). Cutting Edge: p27Kip1 Deficiency Reduces the Requirement for CD28-Mediated Costimulation in Naive CD8+ but Not CD4+ T Lymphocytes. J. Immunol.
174: 2481-2484
[Abstract] [Full Text] -
BARBACID, M., ORTEGA, S., SOTILLO, R., ODAJIMA, J., MARTIN, A., SANTAMARIA, D., DUBUS, P., MALUMBRES, M.
(2005). Cell Cycle and Cancer: Genetic Analysis of the Role of Cyclin-dependent Kinases. Cold Spring Harb Symp Quant Biol
70: 233-240
[Abstract] -
Gagliardi, A. D., Kuo, E. Y. W., Raulic, S., Wagner, G. F., DiMattia, G. E.
(2005). Human stanniocalcin-2 exhibits potent growth-suppressive properties in transgenic mice independently of growth hormone and IGFs. Am. J. Physiol. Endocrinol. Metab.
288: E92-E105
[Abstract] [Full Text] -
Jirawatnotai, S., Aziyu, A., Osmundson, E. C., Moons, D. S., Zou, X., Kineman, R. D., Kiyokawa, H.
(2004). Cdk4 Is Indispensable for Postnatal Proliferation of the Anterior Pituitary. J. Biol. Chem.
279: 51100-51106
[Abstract] [Full Text] -
Sherr, C. J., Roberts, J. M.
(2004). Living with or without cyclins and cyclin-dependent kinases. Genes Dev.
18: 2699-2711
[Abstract] [Full Text] -
Miliani de Marval, P. L., Macias, E., Rounbehler, R., Sicinski, P., Kiyokawa, H., Johnson, D. G., Conti, C. J., Rodriguez-Puebla, M. L.
(2004). Lack of Cyclin-Dependent Kinase 4 Inhibits c-myc Tumorigenic Activities in Epithelial Tissues. Mol. Cell. Biol.
24: 7538-7547
[Abstract] [Full Text] -
Chiles, T. C.
(2004). Regulation and Function of Cyclin D2 in B Lymphocyte Subsets. J. Immunol.
173: 2901-2907
[Abstract] [Full Text] -
Pei, X.-H., Bai, F., Tsutsui, T., Kiyokawa, H., Xiong, Y.
(2004). Genetic Evidence for Functional Dependency of p18Ink4c on Cdk4. Mol. Cell. Biol.
24: 6653-6664
[Abstract] [Full Text] -
Li, T., Inoue, A., Lahti, J. M., Kidd, V. J.
(2004). Failure To Proliferate and Mitotic Arrest of CDK11p110/p58-Null Mutant Mice at the Blastocyst Stage of Embryonic Cell Development. Mol. Cell. Biol.
24: 3188-3197
[Abstract] [Full Text] -
Su, T. T., Stumpff, J.
(2004). Promiscuity Rules? The Dispensability of Cyclin E and Cdk2. Sci Signal
2004: pe11-pe11
[Abstract] [Full Text] -
Cozar-Castellano, I., Takane, K. K., Bottino, R., Balamurugan, A.N., Stewart, A. F.
(2004). Induction of {beta}-Cell Proliferation and Retinoblastoma Protein Phosphorylation in Rat and Human Islets Using Adenovirus-Mediated Transfer of Cyclin-Dependent Kinase-4 and Cyclin D1. Diabetes
53: 149-159
[Abstract] [Full Text] -
Kohoutek, J., Dvorak, P., Hampl, A.
(2004). Temporal Distribution of CDK4, CDK6, D-Type Cyclins, and p27 in Developing Mouse Oocytes. Biol. Reprod.
70: 139-145
[Abstract] [Full Text] -
Jirawatnotai, S., Moons, D. S., Stocco, C. O., Franks, R., Hales, D. B., Gibori, G., Kiyokawa, H.
(2003). The Cyclin-dependent Kinase Inhibitors p27Kip1 and p21Cip1 Cooperate to Restrict Proliferative Life Span in Differentiating Ovarian Cells. J. Biol. Chem.
278: 17021-17027
[Abstract] [Full Text] -
Gonzalez, T., Seoane, M., Caamano, P., Vinuela, J., Dominguez, F., Zalvide, J.
(2003). Inhibition of Cdk4 Activity Enhances Translation of p27kip1 in Quiescent Rb-negative Cells. J. Biol. Chem.
278: 12688-12695
[Abstract] [Full Text] -
Lea, N. C., Orr, S. J., Stoeber, K., Williams, G. H., Lam, E. W.-F., Ibrahim, M. A. A., Mufti, G. J., Thomas, N. S. B.
(2003). Commitment Point during G0->G1 That Controls Entry into the Cell Cycle. Mol. Cell. Biol.
23: 2351-2361
[Abstract] [Full Text] -
Xin, S., Weng, L., Xu, J., Du, W.
(2003). The role of RBF in developmentally regulated cell proliferation in the eye disc and in Cyclin D/Cdk4 induced cellular growth. Development
129: 1345-1356
[Abstract] [Full Text] -
Ciemerych, M. A., Kenney, A. M., Sicinska, E., Kalaszczynska, I., Bronson, R. T., Rowitch, D. H., Gardner, H., Sicinski, P.
(2002). Development of mice expressing a single D-type cyclin. Genes Dev.
16: 3277-3289
[Abstract] [Full Text] -
Zou, X., Ray, D., Aziyu, A., Christov, K., Boiko, A. D., Gudkov, A. V., Kiyokawa, H.
(2002). Cdk4 disruption renders primary mouse cells resistant to oncogenic transformation, leading to Arf/p53-independent senescence. Genes Dev.
16: 2923-2934
[Abstract] [Full Text] -
Kwon, Y. H., Jovanovic, A., Serfas, M. S., Kiyokawa, H., Tyner, A. L.
(2002). p21 Functions to Maintain Quiescence of p27-deficient Hepatocytes. J. Biol. Chem.
277: 41417-41422
[Abstract] [Full Text] -
Moons, D. S., Jirawatnotai, S., Parlow, A. F., Gibori, G., Kineman, R. D., Kiyokawa, H.
(2002). Pituitary Hypoplasia and Lactotroph Dysfunction in Mice Deficient for Cyclin-Dependent Kinase-4. Endocrinology
143: 3001-3008
[Abstract] [Full Text] -
Rodriguez-Puebla, M. L., Miliani de Marval, P. L., LaCava, M., Moons, D. S., Kiyokawa, H., Conti, C. J.
(2002). cdk4 Deficiency Inhibits Skin Tumor Development but Does Not Affect Normal Keratinocyte Proliferation. Am. J. Pathol.
161: 405-411
[Abstract] [Full Text] -
Gartel, A. L., Tyner, A. L.
(2002). The Role of the Cyclin-dependent Kinase Inhibitor p21 in Apoptosis. Molecular Cancer Therapeutics
1: 639-649
[Abstract] [Full Text] -
Vidal, A., Millard, S. S., Miller, J. P., Koff, A.
(2002). Rho Activity Can Alter the Translation of p27 mRNA and Is Important for RasV12-induced Transformation in a Manner Dependent on p27 Status. J. Biol. Chem.
277: 16433-16440
[Abstract] [Full Text] -
Moons, D. S., Jirawatnotai, S., Tsutsui, T., Franks, R., Parlow, A. F., Hales, D. B., Gibori, G., Fazleabas, A. T., Kiyokawa, H.
(2002). Intact Follicular Maturation and Defective Luteal Function in Mice Deficient for Cyclin- Dependent Kinase-4. Endocrinology
143: 647-654
[Abstract] [Full Text] -
Musgrove, E. A., Hunter, L.-J. K., Lee, C. S. L., Swarbrick, A., Hui, R., Sutherland, R. L.
(2001). Cyclin D1 Overexpression Induces Progestin Resistance in T-47D Breast Cancer Cells Despite p27Kip1 Association with Cyclin E-Cdk2. J. Biol. Chem.
276: 47675-47683
[Abstract] [Full Text] -
Wang, Z., Yu, R., Melmed, S.
(2001). Mice Lacking Pituitary Tumor Transforming Gene Show Testicular and Splenic Hypoplasia, Thymic Hyperplasia, Thrombocytopenia, Aberrant Cell Cycle Progression, and Premature Centromere Division. Mol. Endocrinol.
15: 1870-1879
[Abstract] [Full Text] -
Boxem, M., van den Heuvel, S.
(2001). lin-35 Rb and cki-1 Cip/Kip cooperate in developmental regulation of G1 progression in C. elegans. Development
128: 4349-4359
[Abstract] [Full Text] -
Ezhevsky, S. A., Ho, A., Becker-Hapak, M., Davis, P. K., Dowdy, S. F.
(2001). Differential Regulation of Retinoblastoma Tumor Suppressor Protein by G1 Cyclin-Dependent Kinase Complexes In Vivo. Mol. Cell. Biol.
21: 4773-4784
[Abstract] [Full Text] -
Miliani de Marval, P. L., Gimenez-Conti, I. B., LaCava, M., Martinez, L. A., Conti, C. J., Rodriguez-Puebla, M. L.
(2001). Transgenic Expression of Cyclin-Dependent Kinase 4 Results in Epidermal Hyperplasia, Hypertrophy, and Severe Dermal Fibrosis. Am. J. Pathol.
159: 369-379
[Abstract] [Full Text] -
Zindy, F., den Besten, W., Chen, B., Rehg, J. E., Latres, E., Barbacid, M., Pollard, J. W., Sherr, C. J., Cohen, P. E., Roussel, M. F.
(2001). Control of Spermatogenesis in Mice by the Cyclin D-Dependent Kinase Inhibitors p18Ink4c and p19Ink4d. Mol. Cell. Biol.
21: 3244-3255
[Abstract] [Full Text] -
Tong, W., Pollard, J. W.
(2001). Genetic Evidence for the Interactions of Cyclin D1 and p27Kip1 in Mice. Mol. Cell. Biol.
21: 1319-1328
[Abstract] [Full Text] -
Ye, X., Zhu, C., Harper, J. W.
(2001). A premature-termination mutation in the Mus musculus cyclin-dependent kinase 3 gene. Proc. Natl. Acad. Sci. USA
10.1073/pnas.041596198v1
[Abstract] [Full Text] -
Metz, S., Holland, S., Johnson, L., Espling, E., Rabaglia, M., Segu, V., Brockenbrough, J. S., Tran, P. O.
(2001). Inosine-5'-Monophosphate Dehydrogenase Is Required for Mitogenic Competence of Transformed Pancreatic {beta} Cells. Endocrinology
142: 193-204
[Abstract] [Full Text] -
Geng, Y., Yu, Q., Sicinska, E., Das, M., Bronson, R. T., Sicinski, P.
(2000). Deletion of the p27Kip1 gene restores normal development in cyclin D1-deficient mice. Proc. Natl. Acad. Sci. USA
10.1073/pnas.011522998v1
[Abstract] [Full Text] -
Rausa, F. M., Tan, Y., Zhou, H., Yoo, K. W., Stolz, D. B., Watkins, S. C., Franks, R. R., Unterman, T. G., Costa, R. H.
(2000). Elevated Levels of Hepatocyte Nuclear Factor 3beta in Mouse Hepatocytes Influence Expression of Genes Involved in Bile Acid and Glucose Homeostasis. Mol. Cell. Biol.
20: 8264-8282
[Abstract] [Full Text] -
Geng, Y., Yu, Q., Sicinska, E., Das, M., Bronson, R. T., Sicinski, P.
(2001). Deletion of the p27Kip1 gene restores normal development in cyclin D1-deficient mice. Proc. Natl. Acad. Sci. USA
98: 194-199
[Abstract] [Full Text] -
Ye, X., Zhu, C., Harper, J. W.
(2001). A premature-termination mutation in the Mus musculus cyclin-dependent kinase 3 gene. Proc. Natl. Acad. Sci. USA
98: 1682-1686
[Abstract] [Full Text] -
Hermeking, H., Rago, C., Schuhmacher, M., Li, Q., Barrett, J. F., Obaya, A. J., O'Connell, B. C., Mateyak, M. K., Tam, W., Kohlhuber, F., Dang, C. V., Sedivy, J. M., Eick, D., Vogelstein, B., Kinzler, K. W.
(2000). Identification of CDK4 as a target of c-MYC. Proc. Natl. Acad. Sci. USA
97: 2229-2234
[Abstract] [Full Text]
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