Previous Article | Next Article 
Molecular and Cellular Biology, August 2001, p. 5512-5519, Vol. 21, No. 16
Department of Biological
Chemistry1 and Molecular Biology
Institute,2 University of California Los
Angeles, Los Angeles, California 90095-1737
Received 16 March 2001/Returned for modification 30 April
2001/Accepted 24 May 2001
Nonsense-mediated mRNA decay (NMD), the loss of mRNAs carrying
premature stop codons, is a process by which cells recognize and
degrade nonsense mRNAs to prevent possibly toxic effects of truncated
peptides. Most mammalian nonsense mRNAs are degraded while associated
with the nucleus, but a few are degraded in the cytoplasm; at either
site, there is a requirement for translation and for an intron
downstream of the early stop codon. We have examined the NMD of a
mutant HEXA message in lymphoblasts derived from a
Tay-Sachs disease patient homozygous for the common frameshift mutation
1278ins4. The mutant mRNA was nearly undetectable in these cells and
increased to approximately 40% of normal in the presence of the
translation inhibitor cycloheximide. The stabilized transcript was
found in the cytoplasm in association with polysomes. Within 5 h
of cycloheximide removal, the polysome-associated nonsense message was
completely degraded, while the normal message was stable. The increased
lability of the polysome-associated mutant HEXA mRNA
shows that NMD of this endogenous mRNA occurred in the cytoplasm.
Transfection of Chinese hamster ovary cells showed that expression of
an intronless HEXA minigene harboring the frameshift mutation or a closely located nonsense codon resulted in half the
normal mRNA level. Inclusion of multiple downstream introns decreased
the abundance further, to about 20% of normal. Thus, in contrast to
other systems, introns are not absolutely required for NMD of
HEXA mRNA, although they enhance the
low-HEXA-mRNA phenotype.
Investigators studying
genetic disorders have often found that some mutations are associated
with very low levels of mRNA. Barring gross DNA alterations, these are
usually frameshift or nonsense mutations (15, 21-23, 25, 28, 34,
35, 43, 46, 48, 61, 62). Among them are mutations of the
HEXA gene, leading to Tay-Sachs disease (TSD), an
autosomally inherited neurodegenerative disorder (26).
While numerous mutations have been identified as the cause of TSD, the
most common is a 4-bp insertion in exon 11 (1278ins4) of the 14-exon
HEXA gene, shortening the reading frame by 100 codons.
Patient fibroblasts homozygous for this frameshift mutation (or in
compound heterozygosity with a splice site mutation) have undetectable
levels of the nonsense-containing mRNA (48), even though
transcription is normal (52). It is not the frameshift
itself but the premature termination codon 9 nucleotides (nt)
downstream that causes the low-mRNA phenotype (12).
The degradation of mRNAs containing premature stop codons, termed
nonsense-mediated mRNA decay (NMD), is a process of much broader
biological significance than removal of mRNA in genetic disease
(4, 10, 33, 40-42, 44, 54, 56, 57, 66; L. E. Maquat,
Editorial, Am. J. Hum. Genet. 59:279-286, 1996).
Organisms as diverse as yeast (54), worms (51,
56), plants (55), and mammals (41;
Maquat, editorial), demonstrate this phenomenon. It is presumed that
NMD prevents the synthesis of truncated peptides that could have
dominant negative effects on the organism. The process serves as a
general surveillance mechanism to abolish aberrant transcripts
resulting not only from rare mutations but also from mistakes in RNA
processing (56).
Numerous studies in the last decade have addressed the mechanism of
NMD. In Saccharomyces cerevisiae, NMD occurs in the
cytoplasm while the transcript is associated with polysomes
(73). It has been suggested that when an early stop codon
is reached, translation stalls and the message is scanned by specific
factors. If a certain downstream element is encountered (53,
72), and if specific trans factors are present
(1, 2, 20, 36, 53, 60), the message undergoes a type of
conformational change that renders it sensitive to a 5' decapping
enzyme independent of the normal poly(A) tail shortening, followed by a
5'-to-3' exonuclease-mediated degradation (27, 45). Thus,
the data show that in yeast, NMD occurs in the cytoplasm (1, 2,
7, 18, 19, 30, 45, 53, 54, 57-60, 73).
However, very few mammalian nonsense messages studied to date show a
cytoplasmic mode of decay. These include transcripts for Additional suggestions of nuclear involvement in NMD come from
observations that exons harboring an early stop codon are often skipped
(3, 22, 23), implying recognition of the reading frame in
the nucleus. However, this interpretation is not universally accepted,
and the suggestion of a reverse transcription-PCR artifact has been
offered as an explanation for nonsense-mediated exon skipping
(67, 68).
The strongest evidence that nuclear processes are important for NMD in
mammalian cells comes from the failure of intronless minigenes (cDNAs)
to reproduce the decay phenotype (50, 66, 70; X. Sun, and
L. E. Maquat, Letter, RNA 6:1-8, 2000) and from the
requirement for downstream introns (10, 14, 16, 65, 70,
71). To reconcile the nuclear involvement and the requirement
for cytoplasmic translation, it has been proposed that exon-exon
junctions are tagged upon completion of splicing, producing an mRNP
capable of signaling decay when an early stop codon is present at a
proper distance from the tag (31). Some transcripts would
be translated, recognized as nonsense, and degraded in the cytoplasm,
and others would undergo this process while still associated with the
nucleus. In this paper, we address the site of decay and the
requirement for introns for the NMD of the HEXA transcript.
Cell culture.
Normal (GM 03299D) and TSD (GM 11852)
lymphoblasts (Coriell Institute) were cultured in suspension under 5%
CO2 in T75 flasks with RPMI 1640 medium (Life
Technologies) containing 10% fetal bovine serum (Irvine Scientific),
penicillin and streptomycin, nonessential amino acids, and sodium
pyruvate. Cells were passaged 1 to 2 days earlier, so that they
would be at a density of about 2 × 106
cells/ml on the day of the experiment. To inhibit translation, 2 × 107 to 3 × 107
lymphoblasts were pelleted, washed once with phosphate-buffered saline,
and resuspended in medium containing 28 µg of cycloheximide/ml. To
subsequently remove the cycloheximide, cells were pelleted, washed
twice with phosphate-buffered saline, and resuspended in medium without
the inhibitor. The dose of cycloheximide selected, 28 µg/ml,
inhibited translation by 93% after a 4-h incubation, as monitored by
[35S]methionine-cysteine incorporation. After
removal of cycloheximide, total translation increased to 63% of the
initial level within 1 h and remained at that level for an
additional 5 h. To inhibit transcription, 5 µg of actinomycin
D/ml (29, 33, 66) was added to the cycloheximide-free
medium. Chinese hamster ovary cells were cultured under 5%
CO2 in 10-cm plates with alpha minimal essential
medium (Life Technologies) and 5% fetal bovine serum.
RNA extraction.
Total cellular RNA was extracted with RNA
STAT 60 (Tel-Test) as per the supplier's protocol. Nuclear and
cytoplasmic RNAs were isolated by methods described by Jakubowski and
Roberts (32). Briefly, cells were lysed with 500 µl of
lysis buffer (10 mM Tris-HCl [pH 7.5], 1.5 mM
MgCl2, 0.3 M sucrose, 0.5% NP-40, 0.25% sodium deoxycholate, and 0.5 U of RNase inhibitor [Boehringer
Mannheim]/µl) and loaded onto 500 µl of a cushion buffer (10 mM
Tris-HCl [pH 7.5], 1.5 mM MgCl2, and 0.4 M
sucrose). The samples were centrifuged for 10 min at 800 × g. The cytoplasmic supernatant was treated with proteinase
K, extracted with phenol-chloroform, and precipitated with ethanol. The
nuclear pellet was resuspended in 150 µl of high-salt DNase buffer
(10 mM Tris-HCl [pH 7.4], 500 mM NaCl, 5 mM
MgCl2, and 0.1 mM CaCl2)
and incubated for 30 min at 37°C with 100 U of DNase I (Life
Technologies). The samples were then treated with proteinase K,
extracted with phenol-chloroform, and precipitated with ethanol.
Northern blot analysis.
Fifteen-microgram aliquots of total,
nuclear, and cytoplasmic RNA were used for Northern blot analysis. The
RNA was subjected to electrophoresis on a 1% agarose-formaldehyde gel
and blotted onto a nylon membrane. The blots were stained with
methylene blue to visualize the 18S and 28S rRNA and then probed with a
32P-labeled full-length HEXA cDNA, a
360-bp 5' HEXA cDNA, a 600-bp Polysome profile analysis.
Polysomes were isolated following
methods described by Duncan and Burgoyne (24). In brief,
2 × 107 to 3 × 107 lymphoblasts were lysed with 900 µl of
lysis buffer (50 mM Tris-HCl [pH 7.4], 100 mM KCl, 5 mM
MgCl2, 1% Triton X-100, 1% sodium deoxycholate, 1 mg of heparin/ml, and 20 µg of cycloheximide/ml) and loaded onto a
15-to-50% linear sucrose gradient. The sucrose solutions were made
with gradient buffer (50 mM Tris [pH 7.4], 100 mM KCl, and 5 mM
MgCl2) and poured into 14- by 89-cm Beckman
UltraClear centrifuge tubes using a gradient mixer attached to a
peristaltic pump. To disrupt polysomes, 30 mM EDTA was added to the
lysis buffer. Samples were centrifuged at 4°C in an SW41 rotor at
40,000 rpm for 2.5 h. Polysome profiles were created with an ISCO
model 185 gradient fractionator with a tube piercer, attached to a UA-6 absorbance monitor and fraction collector. Fourteen fractions were
collected, and sodium dodecyl sulfate was added to each to a
concentration of 0.5%. RNA was isolated by extraction with
phenol-chloroform and then chloroform alone and precipitated with 3 M
ammonium acetate and ethanol. The entire RNA sample from each fraction
was used for Northern analysis.
Construction of minigenes.
Standard molecular biology
techniques were used in the construction of the normal and mutant
HEXA minigenes and cDNAs. Restriction enzymes were purchased
from Pharmacia, and the PCR enzymes TaqPlus Precision PCR
system and Pfu DNA polymerase were purchased from Stratagene. All constructs were cloned into the pcDNA3.1( (i) Construct 1.
Two HEXA minigenes
(12) with four introns upstream and three downstream of
the mutation were a kind gift from Richard L. Proia (National
Institutes of Health). These minigenes, normal (TK (ii) Construct 2.
The two minigenes were digested with
KpnI and partially digested with SalI to purify a
6.5-kb fragment, which was ligated to a 1.45-kb
SalI/KpnI fragment PCR amplified from the normal HEXA cDNA. This intermediate plasmid was linearized with
KpnI and ligated to a 200-bp KpnI fragment from
the original normal and mutant minigenes, digested with
SalI, and finally cloned into XhoI-linearized
pcDNA3.1( (iii) Construct 3.
Two bands of about 3 and 7.9 kb were gel
purified after digestion of the normal and mutant construct 2 with
HpaI and HindIII. The 3-kb fragment was
further cut with Psp1406I to yield a 550-bp fragment, which
was then ligated to the 7.9-kb HpaI/HindIII
fragment and a 420-bp HindIII/Psp1406I
fragment PCR amplified from the normal HEXA cDNA.
(iv) Construct 4.
Normal 2-kb HEXA cDNA was gel
purified after digestion with XbaI and
HindIII and then cloned into pcDNA3.1( (v) Construct 5.
A 5.4-kb PvuII/EcoRI
fragment of construct 1 was cloned into pGEMEX-1 (Promega) and then
digested with PvuII and BamHI to release a 4.6-kb
vector. This vector was ligated to a 820-bp
PvuII/BamHI fragment obtained either from the
normal or mutant HEXA cDNA. This intermediate construct was
digested with EcoRI yielding a 1.4-kb band that was ligated
to an 8-kb EcoRI fragment of construct 1.
(vi) Construct 6.
The mutant cDNAs (harboring the 1278ins4
or the W392X mutation) were both created with the PCR-based QuickChange
site-directed mutagenesis kit (Stratagene) according to the
manufacturer's protocol. Briefly, the normal HEXA cDNA in
the pGEM-3Zf(+) (Promega) vector was PCR amplified by Pfu
DNA polymerase (Stratagene), known for its high fidelity, with primers
harboring the desired mutation. The nicked DNA was used to transform
XL1-Blue ultracompetent cells after the parental DNA had been digested
with DpnI. The new mutant cDNAs were sequenced to confirm
the presence of the mutation. They were then digested with
XbaI and PstI to release a 2-kb fragment, which
was cloned into pBluescript II KS(+) (Stratagene). This intermediate
construct was cut with XbaI and EcoRI to yield a 2.1-kb band that was finally cloned into pcDNA3.1( Transfections.
CHO cells were transiently transfected with
the various constructs using the Lipofectamine Plus system (Life
Technologies) according to the manufacturer's directions. Transfection
was carried out in 10-cm plates with 4 µg of DNA in serum-free medium
for 3 h. Serum was added to 5%, and about 40 h later, RNA
was extracted for analysis as described above.
Translation is required for decay of nonsense HEXA
mRNA.
The effect of inhibiting translation on nonsense mRNA
abundance was examined by treating normal and TSD lymphoblasts with cycloheximide. Total RNA was analyzed by Northern blotting, which in
these and subsequent experiments showed three distinguishable HEXA species
0270-7306/01/$04.00+0 DOI: 10.1128/MCB.21.16.5512-5519.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Nonsense-Mediated Decay of Human
HEXA mRNA
ABSTRACT
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
INTRODUCTION
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
-globin
from bone marrow cells of transgenic mice (38, 39), Rous
sarcoma virus gag (4, 5), and
selenium-dependent glutathione peroxidase I (44; P. M. Moriarty, C. C. Reddy, and L. E. Maquat, Letter, RNA
3:1369-1373, 1997). Instead, most mammalian nonsense mRNAs
display a nuclear or nucleus-associated mechanism of decay. These
include transcripts for human triosephosphate isomerase (8, 9,
16, 17, 21, 69, 70), human -globin in nonerythroid cells
(6, 71), hamster dihydrofolate reductase (66), hamster adenine phosphoribosyltransferase
(33), mouse major urinary protein (10), and
mouse T-cell receptor (13, 14). With these
transcripts, the level of the nonsense mRNA that fractionates with the
nucleus is reduced to the same degree as the level in the cytoplasm;
furthermore, the nonsense mRNA that escapes into the cytoplasm has
normal stability (6, 9, 10, 17, 21, 33, 62, 66). This
implies that NMD occurs while the message is still associated with the
nucleus. But translation remains essential, as shown by the
stabilization of nonsense mRNAs in the presence of
translation-inhibiting drugs (13, 14), tRNA suppressors
(8), and 5' stem-loop structures that prevent mRNA
translation (8, 65).
MATERIALS AND METHODS
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
-actin cDNA, or an 800-bp
neomycin resistance probe. A riboprobe was synthesized from the plasmid
pSPU4b, kindly provided by Douglas Black (University of California, Los
Angeles), for the 94-nt U4 snRNA probe (11). Radioactivity
was visualized and quantitated with a PhosphorImager (Molecular Dynamics).
) vector (Invitrogen) and were thus driven by the cytomegalovirus (CMV) promoter
and carried a neomycin resistance (neor)
gene. All the mutant constructs except the W392X intronless minigene
carried the 1278ins4 mutation in exon 11. The W392X mutation creates a
stop codon in exon 11, about 114 nt upstream of the stop codon
resulting from 1278ins4.
) and mutant (Mut
TK), were digested with SalI, and the 8.8-kb fragment was
cloned into the XhoI linearized pcDNA3.1() in order to
transfer them from a herpes simplex thymidine kinase promoter to a CMV promoter.
).
). The
intermediate construct was cut with KpnI to release a 72-bp
fragment, which was then replaced with a 273-bp genomic KpnI
fragment with or without the 4-bp mutation.
).
RESULTS
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
a major species of 2.1 kb and two minor
species of 2.6 and 2.4 kb (Fig. 1 and
2). The 2.1-kb mRNA migrated in the region of the 18S rRNA, which occasionally disrupted the hybridization signal. The minor 2.6-kb transcript hybridized with several
nonoverlapping HEXA probes and disappeared within 2 h
of actinomycin D treatment (data not shown); it is therefore thought to
be a pre-mRNA. It was present in normal and mutant cells, appeared to
be insensitive to NMD, and was not studied further. The other minor
species, of 2.4 kb, hybridized to an alternative 3' untranslated
region probe (data not shown), showing that it was the
previously described HEXA mRNA with a longer 3' untranslated
region (47). Though the 2.4-kb message was subject to NMD,
only the abundant full-length 2.1-kb mRNA was used for all analyses.
View larger version (38K):
[in a new window]
FIG. 1.
Stabilization of the nonsense TSD mRNA with
cycloheximide. (Top) Northern blot analysis of total RNA isolated from
lymphoblasts, either normal (lanes 1 and 2) or TSD (lanes 3 and 4),
with and without a 4-h cycloheximide treatment. (Bottom) PhosphorImager
quantitation of the average amount of HEXA mRNA in the
above lanes and in two other experiments, normalized to -actin.
Error bars indicate standard deviations. The mRNA measured is the major
species of 2.1 kb. The two minor species (2.4 [*] and 2.6 [**] kb, respectively) are described in the text.
View larger version (50K):
[in a new window]
FIG. 2.
Decay of the cycloheximide-stabilized pool of
HEXA mRNA. Northern blot analysis of total RNA
isolated from lymphoblasts before treatment (0 h), after a 4-h
treatment with cycloheximide, and 1, 2, 6, and 12 h following
cycloheximide removal. Blots were rehybridized with a -actin cDNA
probe for normalization. Asterisks indicate minor mRNA species as in
Fig. 1.
Cycloheximide-stabilized nonsense HEXA mRNA is found
only in the cytoplasmic fraction.
Cellular fractionation and
Northern blot analysis were used to determine the cellular distribution
of the normal and nonsense HEXA mRNA. As shown in Fig.
3, in the absence of cycloheximide, the
HEXA mRNA was lacking in both the nuclear and cytoplasmic fractions of TSD cells, while it was present almost exclusively in the
cytoplasmic fraction of normal cells. After treatment with cycloheximide, the stabilized TSD mRNA was elevated exclusively in the
cytoplasmic fraction, with no noticeable changes in the nuclear
fraction. (The NMD-insensitive 2.6-kb transcript was seen in all
fractions and is not included in the analysis.) Although some leakage
from nucleus to cytoplasm may have occurred, the nuclear fraction
appeared to be generally intact, as shown by enrichment of the snRNAs
U4 (Fig. 3) and U6 (data not shown).
|
Nonsense HEXA mRNA accumulates on polysomes in the
presence of cycloheximide and disappears from polysomes upon removal of
the inhibitor.
The cytoplasmic HEXA mRNA distribution
was determined by Northern blot analysis of ribosome fractions from
normal and TSD lymphoblasts. Fractionation of cell lysates through a
sucrose gradient separated ribosomal subunits (40S and 60S),
monosomes (80S), and polysomes into 14 fractions. The absorbance
profile of each sample at 254 nm showed polysomes to be abundant in
fractions 9 to 14 (Fig. 4, left panels).
The presence of polysomes in these fractions was verified by the
addition of 30 mM EDTA, which disrupts polysomes, to a sample lysate
prior to centrifugation. In the presence of EDTA, absorbance shifted
from the polysome peaks (fractions 9 to 14) to the upper monosome or
soluble phase (fractions 2 to 7), and most of the
polysome-associated HEXA message shifted to the lighter
fractions (data not shown).
|
-actin
mRNA from TSD cells showed approximately equal loading (Fig. 4c, f, and
i), as did blots of -actin mRNA from normal cells (data not shown).
These experiments show that polysome-associated mutant HEXA
mRNA is subject to degradation when translation is resumed.
Introns are not absolutely required but enhance NMD of
HEXA mRNA.
Intron-containing and intronless
HEXA minigenes (Fig. 5A),
driven by the CMV promoter, were transiently expressed in CHO cells. All but one of the mutant minigenes had the common 1278ins4 mutation, which shortens the reading frame by 100 codons to four-fifths of the
normal frame. An additional nonsense cDNA, W392X, was tested for
comparison, as it also had been shown to result in low mRNA in cells of
TSD patients (61). The nonsense codon W392X is located 117 nt upstream of the nonsense codon of 1278ins4 (Fig. 5A, constructs 6 and 7). For each construct, the HEXA mRNA was subject to
Northern blot analysis (Fig. 5B), quantitated by PhosphorImager, and
normalized to the neor mRNA transcribed
from the same plasmid in order to account for differences in
transfection and RNA recovery (Fig. 5C).
|
| |
DISCUSSION |
|---|
|
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
|
|---|
NMD of mammalian messages occurs most often while the transcript is still associated with the nucleus (6, 8-10, 13, 14, 16, 17, 21, 33, 66, 69-71), though in a few cases it occurs when the mRNA is in the cytoplasm (4, 5, 38, 39, 44; Moriarty et al., letter). Our studies show that NMD of the HEXA mRNA is similar to all other mammalian mRNAs in that ongoing translation is required for decay (Fig. 1 to 4). However, it differs from nucleus-associated NMD (33, 63) in that the cytoplasmic, polysome-associated nonsense HEXA message remains sensitive to decay (Fig. 4); thus, the HEXA transcript may be added to the short list of mammalian messages that follow a cytoplasmic mode of decay. In addition, NMD of the HEXA message differs from that of all mammalian transcripts studied to date (49, 64) in that downstream introns are not absolutely required, although they enhance the process.
Although we have shown degradation of cytoplasmic nonsense HEXA mRNA, we cannot exclude the possibility that some TSD transcripts are degraded while associated with the nucleus. First, we could demonstrate stabilization of the nonsense mRNA pool to only 40% of normal. Second, any increase in nucleus-associated nonsense mRNA in the presence of cycloheximide would not have been observed, because the HEXA mRNA was not detected even in the nuclear fraction of normal cells, implying rapid processing and export of this transcript.
Of the few mammalian mRNAs that follow a cytoplasmic mechanism of decay (5, 38, 39), the glutathione peroxidase I transcript, the one best studied, requires an intron at least 59 nt downstream of the early stop codon (44, 64Moriary et al., letter), as do transcripts that decay while associated with the nucleus (10, 49, 65, 70, 71). To explain the necessity of introns and the requirement of cytoplasmic translation, a model has been proposed in which transcripts, upon completion of splicing, are marked at each exon-exon junction (31, 65, 70, 71). This mRNP would be exported out of the nucleus, translated, and degraded if an early stop codon was reached and there was an exon-exon junction marker at a proper distance downstream. If the proper mRNP structure was not created (i.e., there was no splicing to create a downstream exon-exon junction marker [14], or if the marker was too close to the early stop codon [49, 64]), then that message could escape decay.
Our data showing that intronless HEXA minigenes that harbor nonsense codons give rise to low mRNA add an interesting complexity to the mechanism of NMD; how can the same mechanism operate on intron-containing and intronless genes containing early stop codons with the same effect? As mentioned above, it has been proposed that certain factors bind to exon-exon junctions, and spliceosomal proteins (i.e., SRm160 and hPrp8p) have been found to associate with spliced mRNA at such junctions (37), creating a certain mRNP structure. It could be envisioned that some nonsense transcripts would rely on the process of splicing to create the proper mRNP complex to facilitate NMD, but others, resembling nonsense mRNAs in yeast, would rely partially or exclusively on sequences in cis to create the functionally equivalent mRNP structure. In addition, the mRNP structures derived either with or without splicing could facilitate NMD with different efficiencies. Such may be the case for the HEXA message, for which the decrease in abundance in the absence of introns was not as severe as when introns were present.
To our knowledge, this is the first time intronless nonsense HEXA minigenes have been shown to reproduce, if incompletely, the low-mRNA phenotype. Previously, the level of nonsense HEXA mRNA was found to be normal in transfected COS-1 cells (50). But COS-1 cells may not be suitable for the study of NMD, at least of this transcript. They failed to show NMD when transfected with an intron-containing HEXA minigene, even though the same minigene was subject to NMD in mouse L cells (12).
These results, in the context of the published literature, confirm that NMD in mammalian cells is a multipathway phenomenon, with some transcripts following a nuclear or nucleus-associated pathway and others following a cytoplasmic pathway. It is also possible that the pathways are hierarchical and that nonsense codons can be recognized and degraded, with various efficiencies, at different stages following transcription.
| |
ACKNOWLEDGMENTS |
|---|
We thank Douglas Black (UCLA) for providing the U4 and U6 snRNA probes and Dohn Glitz (UCLA) and David Greenberg (UCLA) for helpful discussions.
This work was supported in part by National Institutes of Health research grant NS22376.
| |
FOOTNOTES |
|---|
* Corresponding author. Mailing address: Department of Biological Chemistry, UCLA School of Medicine, 33-257 CHS, Los Angeles, CA 90095-1737. Phone: (310) 825-7149. Fax: (310) 206-1929. E-mail: eneufeld{at}mednet.ucla.edu.
| |
REFERENCES |
|---|
|
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
|
|---|
| 1. | Atkin, A. L., N. Altamura, P. Leeds, and M. R. Culbertson. 1995. The majority of yeast UPF1 co-localizes with polyribosomes in the cytoplasm. Mol. Biol. Cell 6:611-625[Abstract]. |
| 2. |
Atkin, A. L.,
L. R. Schenkman,
M. Eastham,
J. N. Dahlseid,
M. J. Lelivelt, and M. R. Culbertson.
1997.
Relationship between yeast polyribosomes and Upf proteins required for nonsense mRNA decay.
J. Biol. Chem.
272:22163-22172 |
| 3. | Bach, G., S. M. Moskowitz, P. T. Tieu, A. Matynia, and E. F. Neufeld. 1993. Molecular analysis of Hurler syndrome in Druze and Muslim Arab patients in Israel: multiple allelic mutations of the IDUA gene in a small geographic area. Am. J. Hum. Genet. 53:330-338[Medline]. |
| 4. |
Barker, G. F., and K. Beemon.
1991.
Nonsense codons within the Rous sarcoma virus gag gene decrease the stability of unspliced viral RNA.
Mol. Cell. Biol.
11:2760-2768 |
| 5. |
Barker, G. F., and K. Beemon.
1994.
Rous sarcoma virus RNA stability requires an open reading frame in the gag gene and sequences downstream of the gag-pol junction.
Mol. Cell. Biol.
14:1986-1996 |
| 6. |
Baserga, S. J., and E. J. Benz, Jr.
1992.
Beta-globin nonsense mutation: deficient accumulation of mRNA occurs despite normal cytoplasmic stability.
Proc. Natl. Acad. Sci. USA
89:2935-2939 |
| 7. | Beelman, C. A., and R. Parker. 1995. Degradation of mRNA in eukaryotes. Cell 81:179-183[CrossRef][Medline]. |
| 8. |
Belgrader, P.,
J. Cheng, and L. E. Maquat.
1993.
Evidence to implicate translation by ribosomes in the mechanism by which nonsense codons reduce the nuclear level of human triosephosphate isomerase mRNA.
Proc. Natl. Acad. Sci. USA
90:482-486 |
| 9. |
Belgrader, P.,
J. Cheng,
X. Zhou,
L. S. Stephenson, and L. E. Maquat.
1994.
Mammalian nonsense codons can be cis effectors of nuclear mRNA half-life.
Mol. Cell. Biol.
14:8219-8228 |
| 10. |
Belgrader, P., and L. E. Maquat.
1994.
Nonsense but not missense mutations can decrease the abundance of nuclear mRNA for the mouse major urinary protein, while both types of mutations can facilitate exon skipping.
Mol. Cell. Biol.
14:6326-6336 |
| 11. |
Black, D. L., and A. L. Pinto.
1989.
U5 small nuclear ribonucleoprotein: RNA structure analysis and ATP-dependent interaction with U4/U6.
Mol. Cell. Biol.
9:3350-3359 |
| 12. | Boles, D. J., and R. L. Proia. 1995. The molecular basis of HEXA mRNA deficiency caused by the most common Tay-Sachs disease mutation. Am. J. Hum. Genet. 56:716-724[Medline]. |
| 13. |
Carter, M. S.,
J. Doskow,
P. Morris,
S. Li,
R. P. Nhim,
S. Sandstedt, and M. F. Wilkinson.
1995.
A regulatory mechanism that detects premature nonsense codons in T-cell receptor transcripts in vivo is reversed by protein synthesis inhibitors in vitro.
J. Biol. Chem.
270:28995-29003 |
| 14. | Carter, M. S., S. Li, and M. F. Wilkinson. 1996. A splicing-dependent regulatory mechanism that detects translation signals. EMBO J. 15:5965-5975[Medline]. |
| 15. |
Chang, J. C., and Y. W. Kan.
1979.
0 thalassemia, a nonsense mutation in man.
Proc. Natl. Acad. Sci. USA
76:2886-2889 |
| 16. |
Cheng, J.,
P. Belgrader,
X. Zhou, and L. E. Maquat.
1994.
Introns are cis effectors of the nonsense-codon-mediated reduction in nuclear mRNA abundance.
Mol. Cell. Biol.
14:6317-6325 |
| 17. |
Cheng, J., and L. E. Maquat.
1993.
Nonsense codons can reduce the abundance of nuclear mRNA without affecting the abundance of pre-mRNA or the half-life of cytoplasmic mRNA.
Mol. Cell. Biol.
13:1892-1902 |
| 18. | Czaplinski, K., N. Majlesi, T. Banerjee, and S. W. Peltz. 2000. Mtt1 is a Upf1-like helicase that interacts with the translation termination factors and whose overexpression can modulate termination efficiency. RNA 6:730-743[Abstract]. |
| 19. |
Czaplinski, K.,
M. J. Ruiz-Echevarria,
S. V. Paushkin,
X. Han,
Y. Weng,
H. A. Perlick,
H. C. Dietz,
M. D. Ter-Avanesyan, and S. W. Peltz.
1998.
The surveillance complex interacts with the translation release factors to enhance termination and degrade aberrant mRNAs.
Genes Dev.
12:1665-1677 |
| 20. | Czaplinski, K., Y. Weng, K. W. Hagan, and S. W. Peltz. 1995. Purification and characterization of the Upf1 protein: a factor involved in translation and mRNA degradation. RNA 1:610-623[Abstract]. |
| 21. |
Daar, I. O., and L. E. Maquat.
1988.
Premature translation termination mediates triosephosphate isomerase mRNA degradation.
Mol. Cell. Biol.
8:802-813 |
| 22. | Dietz, H. C., and R. J. Kendzior, Jr. 1994. Maintenance of an open reading frame as an additional level of scrutiny during splice site selection. Nat. Genet. 8:183-188[CrossRef][Medline]. |
| 23. |
Dietz, H. C.,
D. Valle,
C. A. Francomano,
R. J. Kendzior, Jr.,
R. E. Pyeritz, and G. R. Cutting.
1993.
The skipping of constitutive exons in vivo induced by nonsense mutations.
Science
259:680-683 |
| 24. | Duncan, J. S., and R. D. Burgoyne. 1996. Characterization of the effects of Ca2+ depletion on the synthesis, phosphorylation and secretion of caseins in lactating mammary epithelial cells. Biochem. J. 317:487-493. |
| 25. |
Gossage, D. L.,
C. J. Norby-Slycord,
M. S. Hershfield, and M. L. Markert.
1993.
A homozygous 5 base-pair deletion in exon 10 of the adenosine deaminase (ADA) gene in a child with severe combined immunodeficiency and very low levels of ADA mRNA and protein.
Hum. Mol. Genet.
2:1493-1494 |
| 26. | Gravel, R. A., J. T. R. Clarke, M. M. Kaback, D. Mahuran, K. Sandhoff, and K. Suzuki. 1995. The GM2 gangliosidoses, p. 2839-2879. In C. R. Scriver, A. L. Beaudet, W. S. Sly, and D. Valle (ed.), The metabolic and molecular bases of inherited disease, vol. 2. McGraw-Hill, Inc., New York, N.Y. |
| 27. | Hagan, K. W., M. J. Ruiz-Echevarria, Y. Quan, and S. W. Peltz. 1995. Characterization of cis-acting sequences and decay intermediates involved in nonsense-mediated mRNA turnover. Mol. Cell. Biol. 15:809-823[Abstract]. |
| 28. |
Hamosh, A.,
B. J. Rosenstein, and G. R. Cutting.
1992.
CFTR nonsense mutations G542X and W1282X associated with severe reduction of CFTR mRNA in nasal epithelial cells.
Hum. Mol. Genet.
1:542-544 |
| 29. | Hattori, Y., J. C. Vera, C. I. Rivas, N. Bersch, R. C. Bailey, M. E. Geffner, and D. W. Golde. 1996. Decreased insulin-like growth factor I receptor expression and function in immortalized African Pygmy T cells. J. Clin. Endocrinol. Metab. 81:2257-2263[Abstract]. |
| 30. |
He, F.,
S. W. Peltz,
J. L. Donahue,
M. Rosbash, and A. Jacobson.
1993.
Stabilization and ribosome association of unspliced pre-mRNAs in a yeast upf1 mutant.
Proc. Natl. Acad. Sci. USA
90:7034-7038 |
| 31. | Hentze, M. W., and A. E. Kulozik. 1999. A perfect message: RNA surveillance and nonsense-mediated decay. Cell 96:307-310[CrossRef][Medline]. |
| 32. |
Jakubowski, M., and J. L. Roberts.
1994.
Processing of gonadotropin-releasing hormone gene transcripts in the rat brain.
J. Biol. Chem.
269:4078-4083 |
| 33. | Kessler, O., and L. A. Chasin. 1996. Effects of nonsense mutations on nuclear and cytoplasmic adenine phosphoribosyltransferase RNA. Mol. Cell. Biol. 16:4426-4435[Abstract]. |
| 34. |
Kugler, W.,
J. Enssle,
M. W. Hentze, and A. E. Kulozik.
1995.
Nuclear degradation of nonsense mutated beta-globin mRNA: a post-transcriptional mechanism to protect heterozygotes from severe clinical manifestations of beta-thalassemia?
Nucleic Acids Res.
23:413-418 |
| 35. | Lee, J. H., N. Novoradovskaya, B. Rundquist, J. Redwine, C. Saltini, and M. Brantly. 1998. Alpha 1-antitrypsin nonsense mutation associated with a retained truncated protein and reduced mRNA. Mol. Genet. Metab. 63:270-280[CrossRef][Medline]. |
| 36. |
Leeds, P.,
S. W. Peltz,
A. Jacobson, and M. R. Culbertson.
1991.
The product of the yeast UPF1 gene is required for rapid turnover of mRNAs containing a premature translational termination codon.
Genes Dev.
5:2303-2314 |
| 37. |
Le Hir, H.,
M. J. Moore, and L. E. Maquat.
2000.
Pre-mRNA splicing alters mRNP composition: evidence for stable association of proteins at exon-exon junctions.
Genes Dev.
14:1098-1108 |
| 38. | Lim, S. K., and L. E. Maquat. 1992. Human beta-globin mRNAs that harbor a nonsense codon are degraded in murine erythroid tissues to intermediates lacking regions of exon I or exons I and II that have a cap-like structure at the 5' termini. EMBO J. 11:3271-3278[Medline]. |
| 39. |
Lim, S. K.,
C. D. Sigmund,
K. W. Gross, and L. E. Maquat.
1992.
Nonsense codons in human beta-globin mRNA result in the production of mRNA degradation products.
Mol. Cell. Biol.
12:1149-1161 |
| 40. |
Losson, R., and F. Lacroute.
1979.
Interference of nonsense mutations with eukaryotic messenger RNA stability.
Proc. Natl. Acad. Sci. USA
76:5134-5137 |
| 41. | Maquat, L. E. 1995. When cells stop making sense: effects of nonsense codons on RNA metabolism in vertebrate cells. RNA 1:453-465[Abstract]. |
| 42. |
Maquat, L. E., and A. J. Kinniburgh.
1985.
A beta zero-thalassemic beta-globin RNA that is labile in bone marrow cells is relatively stable in HeLa cells.
Nucleic Acids Res
13:2855-2867 |
| 43. | Menon, K. P., and E. F. Neufeld. 1994. Evidence for degradation of mRNA encoding alpha-L-iduronidase in Hurler fibroblasts with premature termination alleles. Cell Mol. Biol. (Noisy-le-Grand) 40:999-1005[Medline]. |
| 44. |
Moriarty, P. M.,
C. C. Reddy, and L. E. Maquat.
1998.
Selenium deficiency reduces the abundance of mRNA for Se-dependent glutathione peroxidase 1 by a UGA-dependent mechanism likely to be nonsense codon-mediated decay of cytoplasmic mRNA.
Mol. Cell. Biol.
18:2932-2939 |
| 45. | Muhlrad, D., and R. Parker. 1994. Premature translational termination triggers mRNA decapping. Nature 370:578-581[CrossRef][Medline]. |
| 46. |
Myerowitz, R., and F. C. Costigan.
1988.
The major defect in Ashkenazi Jews with Tay-Sachs disease is an insertion in the gene for the alpha-chain of beta-hexosaminidase.
J. Biol. Chem.
263:18587-18589 |
| 47. |
Myerowitz, R.,
R. Piekarz,
E. F. Neufeld,
T. B. Shows, and K. Suzuki.
1985.
Human beta-hexosaminidase alpha chain: coding sequence and homology with the beta chain.
Proc. Natl. Acad. Sci. USA
82:7830-7834 |
| 48. |
Myerowitz, R., and R. L. Proia.
1984.
cDNA clone for the alpha-chain of human beta-hexosaminidase: deficiency of alpha-chain mRNA in Ashkenazi Tay-Sachs fibroblasts.
Proc. Natl. Acad. Sci. USA
81:5394-5398 |
| 49. | Nagy, E., and L. E. Maquat. 1998. A rule for termination-codon position within intron-containing genes: when nonsense affects RNA abundance. Trends Biochem. Sci. 23:198-199[CrossRef][Medline]. |
| 50. |
Nishimoto, J.,
A. Tanaka,
E. Nanba, and K. Suzuki.
1991.
Expression of the beta-hexosaminidase alpha subunit gene with the four-base insertion of infantile Jewish Tay-Sachs disease.
J. Biol. Chem.
266:14306-14309 |
| 51. |
Page, M. F.,
B. Carr,
K. R. Anders,
A. Grimson, and P. Anderson.
1999.
SMG-2 is a phosphorylated protein required for mRNA surveillance in Caenorhabditis elegans and related to Upf1p of yeast.
Mol. Cell. Biol.
19:5943-5951 |
| 52. |
Paw, B. H., and E. F. Neufeld.
1988.
Normal transcription of the beta-hexosaminidase alpha-chain gene in the Ashkenazi Tay-Sachs mutation.
J. Biol. Chem.
263:3012-3015 |
| 53. |
Peltz, S. W.,
A. H. Brown, and A. Jacobson.
1993.
mRNA destabilization triggered by premature translational termination depends on at least three cis-acting sequence elements and one trans-acting factor.
Genes Dev.
7:1737-1754 |
| 54. | Peltz, S. W., F. He, E. Welch, and A. Jacobson. 1994. Nonsense-mediated mRNA decay in yeast. Prog. Nucleic Acid Res. Mol. Biol. 47:271-298[Medline]. |
| 55. | Petracek, M. E., T. Nuygen, W. F. Thompson, and L. F. Dickey. 2000. Premature termination codons destabilize ferredoxin-1 mRNA when ferredoxin-1 is translated. Plant J. 21:563-569[CrossRef][Medline]. |
| 56. |
Pulak, R., and P. Anderson.
1993.
mRNA surveillance by the Caenorhabditis elegans smg genes.
Genes Dev.
7:1885-1897 |
| 57. | Ruiz-Echevarria, M. J., K. Czaplinski, and S. W. Peltz. 1996. Making sense of nonsense in yeast. Trends Biochem. Sci. 21:433-438[CrossRef][Medline]. |
| 58. | Ruiz-Echevarría, M. J., C. I. González, and S. W. Peltz. 1998. Identifying the right stop: determining how the surveillance complex recognizes and degrades an aberrant mRNA. EMBO J. 17:575-589[CrossRef][Medline]. |
| 59. | Ruiz-Echevarria, M. J., and S. W. Peltz. 1996. Utilizing the GCN4 leader region to investigate the role of the sequence determinants in nonsense-mediated mRNA decay. EMBO J. 15:2810-2819[Medline]. |
| 60. |
Ruiz-Echevarría, M. J.,
J. M. Yasenchak,
X. Han,
J. D. Dinman, and S. W. Peltz.
1998.
The upf3 protein is a component of the surveillance complex that monitors both translation and mRNA turnover and affects viral propagation.
Proc. Natl. Acad. Sci. USA
95:8721-8726 |
| 61. | Shore, S., J. Tomczak, E. E. Grebner, and R. Myerowitz. 1992. An unusual genotype in an Ashkenazi Jewish patient with Tay-Sachs disease. Hum. Mutat. 1:486-490[CrossRef][Medline]. |
| 62. | Smit, L. S., S. Z. Nasr, M. C. Iannuzzi, and F. S. Collins. 1993. An African-American cystic fibrosis patient homozygous for a novel frameshift mutation associated with reduced CFTR mRNA levels. Hum. Mutat. 2:148-151[CrossRef][Medline]. |
| 63. | Stephenson, L. S., and L. E. Maquat. 1996. Cytoplasmic mRNA for human triosephosphate isomerase is immune to nonsense-mediated decay despite forming polysomes. Biochimie 78:1043-1047[Medline]. |
| 64. | Sun, X., P. M. Moriarty, and L. E. Maquat. 2000. Nonsense-mediated decay of glutathione peroxidase 1 mRNA in the cytoplasm depends on intron position. EMBO J. 19:4734-4744[CrossRef][Medline]. |
| 65. | Thermann, R., G. Neu-Yilik, A. Deters, U. Frede, K. Wehr, C. Hagemeier, M. W. Hentze, and A. E. Kulozik. 1998. Binary specification of nonsense codons by splicing and cytoplasmic translation. EMBO J. 17:3484-3494[CrossRef][Medline]. |
| 66. |
Urlaub, G.,
P. J. Mitchell,
C. J. Ciudad, and L. A. Chasin.
1989.
Nonsense mutations in the dihydrofolate reductase gene affect RNA processing.
Mol. Cell. Biol.
9:2868-2880 |
| 67. | Valentine, C. R. 1998. The association of nonsense codons with exon skipping. Mutat. Res. 411:87-117[CrossRef][Medline]. |
| 68. | Valentine, C. R., and R. H. Heflich. 1997. The association of nonsense mutation with exon-skipping in hprt mRNA of Chinese hamster ovary cells results from an artifact of RT-PCR. RNA 3:660-676[Abstract]. |
| 69. | Zhang, J., and L. E. Maquat. 1996. Evidence that the decay of nucleus-associated nonsense mRNA for human triosephosphate isomerase involves nonsense codon recognition after splicing. RNA 2:235-243[Abstract]. |
| 70. |
Zhang, J.,
X. Sun,
Y. Qian,
J. P. LaDuca, and L. E. Maquat.
1998.
At least one intron is required for the nonsense-mediated decay of triosephosphate isomerase mRNA: a possible link between nuclear splicing and cytoplasmic translation.
Mol. Cell. Biol.
18:5272-5283 |
| 71. | Zhang, J., X. Sun, Y. Qian, and L. E. Maquat. 1998. Intron function in the nonsense-mediated decay of beta-globin mRNA: indications that pre-mRNA splicing in the nucleus can influence mRNA translation in the cytoplasm. RNA 4:801-815[Abstract]. |
| 72. | Zhang, S., M. J. Ruiz-Echevarria, Y. Quan, and S. W. Peltz. 1995. Identification and characterization of a sequence motif involved in nonsense-mediated mRNA decay. Mol. Cell. Biol. 15:2231-2244[Abstract]. |
| 73. | Zhang, S., E. M. Welch, K. Hogan, A. H. Brown, S. W. Peltz, and A. Jacobson. 1997. Polysome-associated mRNAs are substrates for the nonsense-mediated mRNA decay pathway in Saccharomyces cerevisiae. RNA 3:234-244[Abstract]. |
Molecular and Cellular Biology, August 2001, p. 5512-5519, Vol. 21, No. 16
0270-7306/01/$04.00+0 DOI: 10.1128/MCB.21.16.5512-5519.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
This article has been cited by other articles:
-
Barbier, J., Dutertre, M., Bittencourt, D., Sanchez, G., Gratadou, L., de la Grange, P., Auboeuf, D.
(2007). Regulation of H-ras Splice Variant Expression by Cross Talk between the p53 and Nonsense-Mediated mRNA Decay Pathways. Mol. Cell. Biol.
27: 7315-7333
[Abstract] [Full Text] -
Isken, O., Maquat, L. E.
(2007). Quality control of eukaryotic mRNA: safeguarding cells from abnormal mRNA function. Genes Dev.
21: 1833-3856
[Abstract] [Full Text] -
Kamhi, E., Yahalom, G., Kass, G., Hacham, Y., Sperling, R., Sperling, J.
(2006). AUG sequences are required to sustain nonsense-codon-mediated suppression of splicing. Nucleic Acids Res
34: 3421-3433
[Abstract] [Full Text] -
Li, X., Li, W., Wang, H., Bayley, D. L., Cao, J., Reed, D. R., Bachmanov, A. A., Huang, L., Legrand-Defretin, V., Beauchamp, G. K., Brand, J. G.
(2006). Cats Lack a Sweet Taste Receptor. J. Nutr.
136: 1932S-1934S
[Full Text] -
Yamanegi, K., Tang, S., Zheng, Z.-M.
(2005). Kaposi's Sarcoma-Associated Herpesvirus K8{beta} Is Derived from a Spliced Intermediate of K8 Pre-mRNA and Antagonizes K8{alpha} (K-bZIP) To Induce p21 and p53 and Blocks K8{alpha}-CDK2 Interaction. J. Virol.
79: 14207-14221
[Abstract] [Full Text] -
Malonek, S., Rojas, M. C., Hedden, P., Hopkins, P., Tudzynski, B.
(2005). Restoration of Gibberellin Production in Fusarium proliferatum by Functional Complementation of Enzymatic Blocks. Appl. Environ. Microbiol.
71: 6014-6025
[Abstract] [Full Text] -
WACHTEL, C., LI, B., SPERLING, J., SPERLING, R.
(2004). Stop codon-mediated suppression of splicing is a novel nuclear scanning mechanism not affected by elements of protein synthesis and NMD. RNA
10: 1740-1750
[Abstract] [Full Text] -
LeBlanc, J. J., Beemon, K. L.
(2004). Unspliced Rous Sarcoma Virus Genomic RNAs Are Translated and Subjected to Nonsense-Mediated mRNA Decay before Packaging. J. Virol.
78: 5139-5146
[Abstract] [Full Text] -
Ebralidze, A., Wang, Y., Petkova, V., Ebralidse, K., Junghans, R. P.
(2004). RNA Leaching of Transcription Factors Disrupts Transcription in Myotonic Dystrophy. Science
303: 383-387
[Abstract] [Full Text] -
Yang, T., McNally, B. A., Ferrone, S., Liu, Y., Zheng, P.
(2003). A Single-nucleotide Deletion Leads to Rapid Degradation of TAP-1 mRNA in a Melanoma Cell Line. J. Biol. Chem.
278: 15291-15296
[Abstract] [Full Text] -
Lynch, M., Kewalramani, A.
(2003). Messenger RNA Surveillance and the Evolutionary Proliferation of Introns. Mol Biol Evol
20: 563-571
[Abstract] [Full Text] -
Maderazo, A. B., Belk, J. P., He, F., Jacobson, A.
(2003). Nonsense-Containing mRNAs That Accumulate in the Absence of a Functional Nonsense-Mediated mRNA Decay Pathway Are Destabilized Rapidly upon Its Restitution. Mol. Cell. Biol.
23: 842-851
[Abstract] [Full Text] -
Lamba, J. K., Adachi, M., Sun, D., Tammur, J., Schuetz, E. G., Allikmets, R., Schuetz, J. D.
(2003). Nonsense mediated decay downregulates conserved alternatively spliced ABCC4 transcripts bearing nonsense codons. Hum Mol Genet
12: 99-109
[Abstract] [Full Text] -
Perrin-Vidoz, L., Sinilnikova, O. M., Stoppa-Lyonnet, D., Lenoir, G. M., Mazoyer, S.
(2002). The nonsense-mediated mRNA decay pathway triggers degradation of most BRCA1 mRNAs bearing premature termination codons. Hum Mol Genet
11: 2805-2814
[Abstract] [Full Text] -
Maquat, L. E.
(2002). NASty effects on fibrillin pre-mRNA splicing: another case of ESE does it, but proposals for translation-dependent splice site choice live on. Genes Dev.
16: 1743-1753
[Full Text] -
Li, B., Wachtel, C., Miriami, E., Yahalom, G., Friedlander, G., Sharon, G., Sperling, R., Sperling, J.
(2002). Stop codons affect 5' splice site selection by surveillance of splicing. Proc. Natl. Acad. Sci. USA
99: 5277-5282
[Abstract] [Full Text] -
Wilusz, C. J., Wang, W., Peltz, S. W.
(2001). Curbing the nonsense: the activation and regulation of mRNA surveillance. Genes Dev.
15: 2781-2785
[Full Text] -
MAQUAT, L.E., SERIN, G.
(2001). Nonsense-mediated mRNA Decay: Insights into Mechanism from the Cellular Abundance of Human Upf1, Upf2, Upf3, and Upf3X Proteins. Cold Spring Harb Symp Quant Biol
66: 313-320
[Abstract]
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»