scholarly journals Regulation of histone mRNA in the unperturbed cell cycle: evidence suggesting control at two posttranscriptional steps.

1991 ◽  
Vol 11 (5) ◽  
pp. 2416-2424 ◽  
Author(s):  
M E Harris ◽  
R Böhni ◽  
M H Schneiderman ◽  
L Ramamurthy ◽  
D Schümperli ◽  
...  

The levels of histone mRNA increase 35-fold as selectively detached mitotic CHO cells progress from mitosis through G1 and into S phase. Using an exogenous gene with a histone 3' end which is not sensitive to transcriptional or half-life regulation, we show that 3' processing is regulated as cells progress from G1 to S phase. The half-life of histone mRNA is similar in G1- and S-phase cells, as measured after inhibition of transcription by actinomycin D (dactinomycin) or indirectly after stabilization by the protein synthesis inhibitor cycloheximide. Taken together, these results suggest that the change in histone mRNA levels between G1- and S-phase cells must be due to an increase in the rate of biosynthesis, a combination of changes in transcription rate and processing efficiency. In G2 phase, there is a rapid 35-fold decrease in the histone mRNA concentration which our results suggest is due primarily to an altered stability of histone mRNA. These results are consistent with a model for cell cycle regulation of histone mRNA levels in which the effects on both RNA 3' processing and transcription, rather than alterations in mRNA stability, are the major mechanisms by which low histone mRNA levels are maintained during G1.

1991 ◽  
Vol 11 (5) ◽  
pp. 2416-2424
Author(s):  
M E Harris ◽  
R Böhni ◽  
M H Schneiderman ◽  
L Ramamurthy ◽  
D Schümperli ◽  
...  

The levels of histone mRNA increase 35-fold as selectively detached mitotic CHO cells progress from mitosis through G1 and into S phase. Using an exogenous gene with a histone 3' end which is not sensitive to transcriptional or half-life regulation, we show that 3' processing is regulated as cells progress from G1 to S phase. The half-life of histone mRNA is similar in G1- and S-phase cells, as measured after inhibition of transcription by actinomycin D (dactinomycin) or indirectly after stabilization by the protein synthesis inhibitor cycloheximide. Taken together, these results suggest that the change in histone mRNA levels between G1- and S-phase cells must be due to an increase in the rate of biosynthesis, a combination of changes in transcription rate and processing efficiency. In G2 phase, there is a rapid 35-fold decrease in the histone mRNA concentration which our results suggest is due primarily to an altered stability of histone mRNA. These results are consistent with a model for cell cycle regulation of histone mRNA levels in which the effects on both RNA 3' processing and transcription, rather than alterations in mRNA stability, are the major mechanisms by which low histone mRNA levels are maintained during G1.


2000 ◽  
Vol 20 (12) ◽  
pp. 4188-4198 ◽  
Author(s):  
Michael L. Whitfield ◽  
Lian-Xing Zheng ◽  
Amy Baldwin ◽  
Tomohiko Ohta ◽  
Myra M. Hurt ◽  
...  

ABSTRACT The expression of the replication-dependent histone mRNAs is tightly regulated during the cell cycle. As cells progress from G1 to S phase, histone mRNA levels increase 35-fold, and they decrease again during G2 phase. Replication-dependent histone mRNAs are the only metazoan mRNAs that lack polyadenylated tails, ending instead in a conserved stem-loop. Much of the cell cycle regulation is posttranscriptional and is mediated by the 3′ stem-loop. A 31-kDa stem-loop binding protein (SLBP) binds the 3′ end of histone mRNA. The SLBP is necessary for pre-mRNA processing and accompanies the histone mRNA to the cytoplasm, where it is a component of the histone messenger RNP. We used synchronous CHO cells selected by mitotic shakeoff and HeLa cells synchronized at the G1/S or the M/G1 boundary to study the regulation of SLBP during the cell cycle. In each system the amount of SLBP is regulated during the cell cycle, increasing 10- to 20-fold in the late G1 and then decreasing in the S/G2border. SLBP mRNA levels are constant during the cell cycle. SLBP is regulated at the level of translation as cells progress from G1 to S phase, and the protein is rapidly degraded as they progress into G2. Regulation of SLBP may account for the posttranscriptional component of the cell cycle regulation of histone mRNA.


1984 ◽  
Vol 4 (11) ◽  
pp. 2364-2369
Author(s):  
A Artishevsky ◽  
A M Delegeane ◽  
A S Lee

Temporal analysis of DNA replication and histone mRNA accumulation in a hamster fibroblast cell cycle mutant (K12) showed that histone mRNA accumulates periodically during the cell cycle and reaches its highest level in the S phase. The direct correlation between the initiation of DNA synthesis and the accumulation of histone mRNA to high levels in S phase demonstrated the strict interdependence of these two events. Moreover, a critical period necessary for histone mRNA accumulation occurred late in G1 phase. If cells were incubated at the nonpermissive temperature during this critical period, the amount of histone mRNA remained at the basal level. Transcription rate measurements indicated that the triggering of histone mRNA synthesis occurred in late G1 and this mRNA was synthesized at its maximal rate 3 to 5 h before its peak of accumulation. However, if cells were prohibited from synthesizing DNA as a consequence of the temperature-sensitive block in G1, the synthesis of histone mRNA was not initiated.


2008 ◽  
Vol 28 (14) ◽  
pp. 4469-4479 ◽  
Author(s):  
M. Murat Koseoglu ◽  
Lee M. Graves ◽  
William F. Marzluff

ABSTRACT Histone mRNA levels are cell cycle regulated, and a major regulatory mechanism is restriction of stem-loop binding protein (SLBP) to S phase. Degradation of SLBP at the end of S phase results in cessation of histone mRNA biosynthesis, preventing accumulation of histone mRNA until SLBP is synthesized just before entry into the next S phase. Degradation of SLBP requires an SFTTP (58 to 62) and KRKL (95 to 98) sequence, which is a putative cyclin binding site. A fusion protein with the 58-amino-acid sequence of SLBP (amino acids 51 to 108) fused to glutathione S-transferase (GST) is sufficient to mimic SLBP degradation at late S phase. Using GST-SLBP fusion proteins as a substrate, we show that cyclin A/Cdk1 phosphorylates Thr61. Furthermore, knockdown of Cdk1 by RNA interference stabilizes SLBP at the end of S phase. Phosphorylation of Thr61 is necessary for subsequent phosphorylation of Thr60 by CK2 in vitro. Inhibitors of CK2 also prevent degradation of SLBP at the end of S phase. Thus, phosphorylation of Thr61 by cyclin A/Cdk1 primes phosphorylation of Thr60 by CK2 and is responsible for initiating SLBP degradation. We conclude that the increase in cyclin A/Cdk1 activity at the end of S phase triggers degradation of SLBP at S/G2.


1984 ◽  
Vol 4 (12) ◽  
pp. 2723-2734
Author(s):  
H L Sive ◽  
N Heintz ◽  
R G Roeder

We have examined the effects of protein synthesis inhibition on histone gene expression during the HeLa cell cycle. Histone mRNAs, which normally are rapidly degraded in the absence of DNA synthesis, persist and increase in concentration when translation is inhibited before DNA replication is halted. This is not a function of polysomal shielding of these mRNAs from active degradation mechanisms since inhibitors of translation initiation alone effect stabilization and induction. The superinduction of histone mRNAs by protein synthesis inhibition is effective at the G1/S border, and in the S-phase and non-S-phase periods of the cell cycle. However, the relative increase in histone mRNA is greater when cells not synthesizing DNA are treated with a protein synthesis inhibitor than when S-phase cells are so treated. Non-histone mRNAs examined are not superinduced by translation inhibition. Transcription rates from both histone and non-histone genes increase after protein synthesis inhibition. Although the decrease in histone gene transcription associated with DNA synthesis inhibition is prevented and reversed by protein synthesis inhibition, we have no evidence that histone gene-specific transcriptional regulation is dependent on protein synthesis. Transcriptional increases may contribute to the superinduction effect but cannot explain its differential extent during the cell cycle, since these increases are similar when replicating or nonreplicating cells are treated with a protein synthesis inhibitor. We believe that changes in histone mRNA stability can account for much of the differential superinduction effect. Our results indicate a requirement for continuing protein synthesis in the cell cycle regulation of histone mRNAs.


1984 ◽  
Vol 4 (11) ◽  
pp. 2364-2369 ◽  
Author(s):  
A Artishevsky ◽  
A M Delegeane ◽  
A S Lee

Temporal analysis of DNA replication and histone mRNA accumulation in a hamster fibroblast cell cycle mutant (K12) showed that histone mRNA accumulates periodically during the cell cycle and reaches its highest level in the S phase. The direct correlation between the initiation of DNA synthesis and the accumulation of histone mRNA to high levels in S phase demonstrated the strict interdependence of these two events. Moreover, a critical period necessary for histone mRNA accumulation occurred late in G1 phase. If cells were incubated at the nonpermissive temperature during this critical period, the amount of histone mRNA remained at the basal level. Transcription rate measurements indicated that the triggering of histone mRNA synthesis occurred in late G1 and this mRNA was synthesized at its maximal rate 3 to 5 h before its peak of accumulation. However, if cells were prohibited from synthesizing DNA as a consequence of the temperature-sensitive block in G1, the synthesis of histone mRNA was not initiated.


2003 ◽  
Vol 185 (6) ◽  
pp. 1825-1830 ◽  
Author(s):  
Kenneth C. Keiler ◽  
Lucy Shapiro

ABSTRACT SsrA, or tmRNA, is a small RNA found in all bacteria that intervenes in selected translation reactions to target the nascent polypeptide for rapid proteolysis. We have found that the abundance of SsrA RNA in Caulobacter crescentus is regulated with respect to the cell cycle. SsrA RNA abundance increases in late G1 phase, peaks during the G1-S transition, and declines in early S phase, in keeping with the reported role for SsrA in the timing of DNA replication initiation. Cell cycle regulation of SsrA RNA is accomplished by a combination of temporally controlled transcription and regulated RNA degradation. Transcription from the ssrA promoter peaks late in G1, just before the peak in SsrA RNA abundance. SsrA RNA is stable in G1-phase cells and late S-phase cells but is degraded with a half-life of 4 to 5 min at the onset of S phase. This degradation is surprising, since SsrA RNA is both highly structured and highly abundant. This is the first observation of a structural RNA that is cell cycle regulated.


1991 ◽  
Vol 11 (1) ◽  
pp. 544-553
Author(s):  
T D Morris ◽  
L A Weber ◽  
E Hickey ◽  
G S Stein ◽  
J L Stein

A major component of the regulation of histone protein synthesis during the cell cycle is the modulation of the half-life of histone mRNA. We have uncoupled transcriptional and posttranscriptional regulation by using a Drosophila hsp70-human H3 histone fusion gene that produces a marked human H3 histone mRNA upon heat induction. Transcription of this gene can be switched on and off by raising and lowering cell culture temperatures, respectively. HeLa cell lines containing stably integrated copies of the fusion gene were synchronized by double thymidine block. Distinct populations of H3 histone mRNA were produced by heat induction in early S-phase, late S-phase, or G2-phase cells, and the stability of the induced H3 histone mRNA was measured. The H3 histone mRNA induced during early S phase decayed with a half-life of 110 min, whereas the same transcript induced during late S phase had a half-life of 10 to 15 min. The H3 histone mRNA induced in non-S-phase cells is more stable than that induced in late S phase, with a half-life of 40 min. Thus, the stability of histone mRNA is actively regulated throughout the cell cycle. Our results are consistent with an autoregulatory model in which the stability of histone mRNA is determined by the level of free histone protein in the cytoplasm.


2021 ◽  
Vol 12 ◽  
Author(s):  
Mengxue Jiang ◽  
Zhijian Kuang ◽  
Yaohui He ◽  
Yin Cao ◽  
Tingyan Yu ◽  
...  

In diabetes mellitus, death of β cell in the pancreas occurs throughout the development of the disease, with loss of insulin production. The maintenance of β cell number is essential to maintaining normoglycemia. SNAPIN has been found to regulate insulin secretion, but whether it induces β cell proliferation remains to be elucidated. This study aimed to explore the physiological roles of SNAPIN in β cell proliferation. SNAPIN expression increases with the age of mice and SNAPIN is down-regulated in diabetes. KEGG pathway and GO analysis showed that SNAPIN- interacting proteins were enriched in cell cycle regulation. B cell cycle was arrested in the S phase, and cell proliferation was inhibited after SNAPIN knockdown. The expression of CDK2, CDK4 and CCND1 proteins in the S phase of the cell cycle were reduced after SNAPIN knockdown, whereas they were increased after overexpression of SNAPIN. In addition, insulin protein and mRNA levels also increased or decreased after SNAPIN knockdown or overexpression, respectively. Conclusions: Our data indicate that SNAPIN mediates β cells proliferation and insulin secretion, and provide evidences that SNAPIN might be a pharmacotherapeutic target for diabetes mellitus.


1991 ◽  
Vol 11 (1) ◽  
pp. 544-553 ◽  
Author(s):  
T D Morris ◽  
L A Weber ◽  
E Hickey ◽  
G S Stein ◽  
J L Stein

A major component of the regulation of histone protein synthesis during the cell cycle is the modulation of the half-life of histone mRNA. We have uncoupled transcriptional and posttranscriptional regulation by using a Drosophila hsp70-human H3 histone fusion gene that produces a marked human H3 histone mRNA upon heat induction. Transcription of this gene can be switched on and off by raising and lowering cell culture temperatures, respectively. HeLa cell lines containing stably integrated copies of the fusion gene were synchronized by double thymidine block. Distinct populations of H3 histone mRNA were produced by heat induction in early S-phase, late S-phase, or G2-phase cells, and the stability of the induced H3 histone mRNA was measured. The H3 histone mRNA induced during early S phase decayed with a half-life of 110 min, whereas the same transcript induced during late S phase had a half-life of 10 to 15 min. The H3 histone mRNA induced in non-S-phase cells is more stable than that induced in late S phase, with a half-life of 40 min. Thus, the stability of histone mRNA is actively regulated throughout the cell cycle. Our results are consistent with an autoregulatory model in which the stability of histone mRNA is determined by the level of free histone protein in the cytoplasm.


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