scholarly journals Stat Proteins Control Lymphocyte Proliferation by Regulating p27Kip1 Expression

1998 ◽  
Vol 18 (4) ◽  
pp. 1996-2003 ◽  
Author(s):  
Mark H. Kaplan ◽  
Carla Daniel ◽  
Ulrike Schindler ◽  
Michael J. Grusby
Keyword(s):  
Cell Cycle ◽  
Proliferative Response ◽  
S Phase ◽  
Interleukin 4 ◽  
Activated T Cells ◽  
Stat Proteins ◽  
Protein Levels ◽  
Proliferation Of Lymphocytes ◽  
Cytokine Stimulation ◽  
Stimulation Of

ABSTRACT The proliferation of lymphocytes in response to cytokine stimulation is essential for a variety of immune responses. Recent studies with signal transducer and activator of transcription 6 (Stat6)-deficient mice have demonstrated that this protein is required for the normal proliferation of lymphocytes in response to interleukin-4 (IL-4). In this report, we show that the impaired IL-4-induced proliferative response of Stat6-deficient lymphocytes is not due to an inability to activate alternate signaling pathways, such as those involving insulin receptor substrates, or to a failure to upregulate IL-4 receptor levels. Cell cycle analysis showed that the percentage of Stat6-deficient lymphocytes that transit from the G1 to the S phase of the cell cycle following IL-4 stimulation is lower than that of control lymphocytes. Although the regulation of many genes involved in the control of cytokine-induced proliferation is normal in Stat6-deficient lymphocytes, protein levels of the cdk inhibitor p27Kip1 were found to be markedly dysregulated. p27Kip1 is expressed at significantly higher levels in Stat6-deficient lymphocytes than in control cells following IL-4 stimulation. The higher level of p27Kip1 expression seen in IL-4-stimulated Stat6-deficient lymphocytes correlates with decreased cdk2-associated kinase activity and is the result of the increased accumulation of protein rather than altered mRNA expression. Similarly, higher levels of p27Kip1 protein expression are also seen following IL-12 stimulation of Stat4-deficient lymphocytes than are seen following stimulation of control cells. These data suggest that Stat proteins may control the cytokine-induced proliferative response of activated T cells by regulating the expression of cell cycle inhibitors so that cyclin-cdk complexes may function to promote transition from the G1 to the S phase of the cell cycle.

scholarly journals The Saccharomyces cerevisiae YAK1 gene encodes a protein kinase that is induced by arrest early in the cell cycle.

1991 ◽  
Vol 11 (8) ◽  
pp. 4045-4052 ◽  
Author(s):  
S Garrett ◽  
M M Menold ◽  
J R Broach
Keyword(s):  
Cell Cycle ◽  
Protein Kinase ◽  
Kinase Activity ◽  
Specific Activity ◽  
S Phase ◽  
Protein Kinase Activity ◽  
Dependent Protein Kinase ◽  
Protein Levels ◽  
Cycle Arrest ◽  
Dependent Protein

Null mutations in the gene YAK1, which encodes a protein with sequence homology to known protein kinases, suppress the cell cycle arrest phenotype of mutants lacking the cyclic AMP-dependent protein kinase (A kinase). That is, loss of the YAK1 protein specifically compensates for loss of the A kinase. Here, we show that the protein encoded by YAK1 has protein kinase activity. Yak1 kinase activity is low during exponential growth but is induced at least 50-fold by arrest of cells prior to the completion of S phase. Induction is not observed by arrest at stages later in the cell cycle. Depending on the arrest regimen, induction can occur either by an increase in Yak1 protein levels or by an increase in Yak1 specific activity. Finally, an increase in Yak1 protein levels causes growth arrest of cells with attenuated A kinase activity. These results suggest that Yak1 acts in a pathway parallel to that of the A kinase to negatively regulate cell proliferation.

scholarly journals Adenosine 3':5'-monophosphate content and actions in the division cycle of synchronized HeLa cells.

1976 ◽  
Vol 71 (2) ◽  
pp. 515-534 ◽  
Author(s):  
C E Zeilig ◽  
R A Johnson ◽  
E W Sutherland ◽  
D L Friedman
Keyword(s):  
Cell Cycle ◽  
Cyclic Amp ◽  
Hela Cells ◽  
S Phase ◽  
Intracellular Camp ◽  
Specific Effects ◽  
Low Concentrations ◽  
High Concentrations ◽  
Camp Levels ◽  
Stimulation Of

The involvement of adenosine 3':5'-monophosphate (cAMP) in the regulation of the cell cycle was studied by determining intracellular fluctuations in cAMP levels in synchronized HeLa cells and by testing the effects of experimentally altered levels on cell cycle traverse. Cyclic AMP levels were lowest during mitosis and were highest during late G-1 or early S phase. These findings were supported by results obtained when cells were accumulated at these points with Colcemid or high levels of thymidine. Additional fluctuations in cAMP levels were observed during S phase. Two specific effects of cAMP on cell cycle traverse were found. Elevation of cAMP levels in S phase or G-2 caused arrest of cells in G-2 for as long as 10 h and lengthened M. However, once cells reached metaphase, elevation of cAMP accelerated the completion of mitosis. Stimulation of mitosis was also observed after addition of CaCl2. The specificity of the effects of cAMP was verified by demonstrating that: (a) intracellular cAMP was increased after exposure to methylisobutylxanthine (MIX) before any observed effects on cycle traverse; (b) submaximal concentrations of MIX potentiated the effects of isoproterenol; and (c) effects of MIX and isoproterenol were mimicked by 8-Br-cAMP. MIX at high concentrations inhibited G-1 traverse, but this effect did not appear to be mediated by cAMP. Isoproterenol slightly stimulated G-1 traverse and partially prevented the MIX-induced delay. Moreover, low concentrations of 8-Br-cAMP (0.10-100 muM) stimulated G-1 traverse, whereas high concentrations (1 mM) inhibited. Both of these effects were also observed with the control, Br-5'-AMP, at 10-fold lower concentrations.

scholarly journals The jun and fos protein families are both required for cell cycle progression in fibroblasts.

1991 ◽  
Vol 11 (9) ◽  
pp. 4466-4472 ◽  
Author(s):  
K Kovary ◽  
R Bravo
Keyword(s):  
Cell Cycle ◽  
Transcription Factors ◽  
Dna Synthesis ◽  
Cell Cycle Progression ◽  
S Phase ◽  
3T3 Cells ◽  
Cycle Progression ◽  
Serum Stimulation ◽  
Fos Protein ◽  
Stimulation Of

The expression of different members of the Jun and Fos families of transcription factors is rapidly induced following serum stimulation of quiescent fibroblasts. To determine whether these proteins are required for cell cycle progression, we microinjected affinity-purified antibodies directed against c-Fos, FosB, Fra-1, c-Jun, JunB, and JunD, and antibodies that recognize either the Fos or the Jun family of proteins, into Swiss 3T3 cells and determined their effects in cell cycle progression by monitoring DNA synthesis. We found that microinjection of anti-Fos and anti-Jun family antibodies efficiently blocked the entrance to the S phase of serum-stimulated or asynchronously growing cells. However, the antibodies against single members of the Fos family only partially inhibited DNA synthesis. In contrast, all three Jun antibodies prevented DNA synthesis more effectively than did any of the anti-Fos antibodies.

scholarly journals Novel Control of S Phase of the Cell Cycle by Ubiquitin-conjugating Enzyme H7

2009 ◽  
Vol 20 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Elizabeth A. Whitcomb ◽  
Edward J. Dudek ◽  
Qing Liu ◽  
Allen Taylor
Keyword(s):  
Cell Cycle ◽  
S Phase ◽  
Regulatory Proteins ◽  
Protein Levels ◽  
Proteolytic Pathway ◽  
Dynamic Cell ◽  
Ubiquitin Conjugating Enzyme ◽  
Phase Progression ◽  
Cycle Dependent ◽  
Cycle Regulation

Timely degradation of regulatory proteins by the ubiquitin proteolytic pathway (UPP) is an established paradigm of cell cycle regulation during the G2/M and G1/S transitions. Less is known about roles for the UPP during S phase. Here we present evidence that dynamic cell cycle–dependent changes in levels of UbcH7 regulate entrance into and progression through S phase. In diverse cell lines, UbcH7 protein levels are dramatically reduced in S phase but are fully restored by G2. Knockdown of UbcH7 increases the proportion of cells in S phase and doubles the time to traverse S phase, whereas UbcH7 overexpression reduces the proportion of cells in S phase. These data suggest a role for UbcH7 targets in the completion of S phase and entry into G2. Notably, UbcH7 knockdown was coincident with elevated levels of the checkpoint kinase Chk1 but not Chk2. These results argue that UbcH7 promotes S phase progression to G2 by modulating the intra-S phase checkpoint mediated by Chk1. Furthermore, UbcH7 levels appear to be regulated by a UPP. Together the data identify novel roles for the UPP, specifically UbcH7 in the regulation of S phase transit time as well as in cell proliferation.

scholarly journals ATF6 knockdown decreases apoptosis, arrests the S phase of the cell cycle, and increases steroid hormone production in mouse granulosa cells

2017 ◽  
Vol 312 (3) ◽  
pp. C341-C353 ◽  
Author(s):  
Yongjie Xiong ◽  
Huatao Chen ◽  
Pengfei Lin ◽  
Aihua Wang ◽  
Lei Wang ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Er Stress ◽  
Granulosa Cells ◽  
Physiological Function ◽  
Steroid Hormone ◽  
Follicular Development ◽  
S Phase ◽  
Mrna Levels ◽  
Hormone Production ◽  
Protein Levels

Activating transcription factor 6 (ATF6), a sensor protein located in the endoplasmic reticulum (ER) membrane, is an important factor in the ER stress signaling pathway. ER stress is known to be involved in folliculogenesis, follicular growth, and ovulation; however, the physiological function of ATF6 in mouse granulosa cells remains largely unknown. The aim of this study was to assess the role of ATF6 in mouse granulosa cells with respect to apoptosis, the cell cycle, and steroid hormone production, as well as several key genes related to follicular development, via RNA interference, immunohistochemical staining, real-time quantitative PCR, Western blotting, flow cytometry, terminal deoxynucleotidyltransferase-mediated deoxy-UTP nick end labeling (TUNEL) assay, and ELISA. Immunohistochemical staining revealed that ATF6 was extensively distributed in the granulosa cells of various ovarian follicles and oocytes in adult female mice. FSH or LH treatment significantly increased ATF6 protein levels in mouse granulosa cells. In the meantime, a recombinant plasmid was used to deplete ATF6 successfully using short hairpin RNA-mediated interference technology, which was verified at both the mRNA and protein levels. Flow cytometry and TUNEL assay analysis indicated that ATF6 depletion decreased apoptosis and arrested the S phase of the cell cycle in mouse granulosa cells. Consistent with these results, p53, caspase-3, B cell lymphoma 2 (Bcl-2)-associated X protein, CCAAT-enhancer-binding protein homologous protein, cyclin A1, cyclin B1, and cyclin D2 mRNA expression decreased, whereas Bcl-2 and glucose-regulated protein 78 kDa mRNA expression increased. Interestingly, ATF6 knockdown obviously increased progesterone and estradiol production in mouse granulosa cells. Cytochrome P450 1b1 ( Cyp1b1) mRNA levels were downregulated, whereas Cyp11a1, steroidogenic acute regulatory, and Cyp19a1 mRNA levels were upregulated, in keeping with the changes in steroid hormones. Furthermore, ATF6 disruption remarkably increased insulin-like growth factor binding protein 4 ( Igfbp4) expression and decreased hyaluronan synthase 2 ( Has2), prostaglandin-endoperoxide synthase 2 ( Ptgs2), and prostaglandin F receptor ( Ptgfr) expression in mouse granulosa cells, which are proteins crucial for follicular development. But, after treating with tunicamycin, the levels of Has2, Ptgs2, and Ptgfr increased relatively, whereas Igfbp4 expression decreased. Collectively, these results imply that ATF6, as a key player in ER stress signaling, may regulate apoptosis, the cell cycle, steroid hormone synthesis, and other modulators related to folliculogenesis in mouse granulosa cells, which may indirectly be involved in the development, ovulation, and atresia of ovarian follicles by affecting the physiological function of granulosa cells. The present study extends our understanding and provides new insights into the physiological significance of ATF6, a key signal transducer of ER stress, in ovarian granulosa cells.

scholarly journals Stimulation of 3-hydroxy-3-methylglutaryl-coenzyme A reductase in mouse uterine epithelial cells by oestradiol-17 β

1984 ◽  
Vol 218 (3) ◽  
pp. 849-855 ◽  
Author(s):  
P A Wilce ◽  
L Leijten ◽  
L Martin
Keyword(s):  
Cell Cycle ◽  
Enzyme Activity ◽  
Epithelial Cells ◽  
Time Course ◽  
Hormone Treatment ◽  
S Phase ◽  
Uterine Epithelial Cells ◽  
Coa Reductase ◽  
Two Peaks ◽  
Stimulation Of

The characteristics of 3-hydroxy-3-methylglutaryl-CoA reductase from mouse uterine epithelial cells were studied. Preliminary experiments showed that enzyme activity was stimulated approx. 10-fold 18h after administration of 100ng of oestradiol-17 beta. This activity was associated with all particulate fractions of the uterine luminal cell. The Km for D-3-hydroxy-3-methylglutaryl-CoA was 5.54 +/- 1.12 microM. The detailed time-course of oestrogen stimulation showed two peaks of activity, 9 and 15h after hormone treatment. The DNA content of the epithelial cells doubled between 6 and 12h after hormone treatment, whereas the protein content increased linearly over the 18h period. The peak of enzyme activity at 9h is associated with early S phase of the epithelial cells; the peak at 15h may be associated with a second S phase or with mitosis. Pretreatment with progesterone for 3 days before injection of oestradiol-17 beta (a treatment which inhibits uterine epithelial DNA synthesis) reduced the oestrogenic stimulation of enzyme activity by 63%; progesterone treatment alone did not stimulate enzyme activity. These data suggest that uterine epithelial 3-hydroxy-3-methylglutaryl-CoA reductase may play an important role in the cell cycle in this tissue.

1,25-Dihydroxyvitamin D3 regulation of cardiac myocyte proliferation and hypertrophy

1997 ◽  
Vol 272 (4) ◽  
pp. H1751-H1758 ◽  
Author(s):  
T. D. O'Connell ◽  
J. E. Berry ◽  
A. K. Jarvis ◽  
M. J. Somerman ◽  
R. U. Simpson
Keyword(s):  
Cell Cycle ◽  
Cardiac Myocyte ◽  
S Phase ◽  
Neonatal Rat ◽  
Nuclear Antigen ◽  
Dihydroxyvitamin D3 ◽  
Myocyte Hypertrophy ◽  
Protein Levels ◽  
1,25 Dihydroxyvitamin D3 ◽  
Myocyte Proliferation

We previously demonstrated that 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] inhibits myocyte maturation (T. D. O'Connell, D. A. Giacherio, A. K. Jarvis, and R. U. Simpson. Endocrinology 136: 482-488, 1995). To define further the role of 1,25(OH)2D3 in regulating myocardial development, we examined the effects of 1,25(OH)2D3 on proliferation and growth of primary cultures of ventricular myocytes isolated from neonatal rat hearts. When neonatal myocytes were grown in a serum-supplemented medium, cell number approximately doubled, and treating these myocytes with 1,25(OH)2D3 inhibited their proliferation by 56.56% after 4 days. Flow cytometry revealed that 1,25(OH)2D3 reduced the percentage of cells in the S phase of the cell cycle by 31.39% after 4 days. We show for the first time that proliferating cell nuclear antigen protein levels were specifically reduced by 1,25(OH)2D3. Protooncogene c-myc protein levels were also reduced by this hormone. Interestingly, a phorbol ester had a similar effect on myocyte proliferation. Furthermore, 1,25(OH)2D3 increased myocyte protein levels and increased cell size, suggesting that it induces cardiac myocyte hypertrophy. Our findings indicate that 1,25(OH)2D3 and phorbol esters directly regulate myocyte proliferation and induce myocyte hypertrophy. Finally, the data demonstrate that the mechanism by which 1,25(OH)2D3 regulates myocyte proliferation involves blocking entry into the S phase of the cell cycle.

The ZF87/MAZ transcription factor functions as a growth suppressor in fibroblasts

2000 ◽  
Vol 78 (4) ◽  
pp. 477-485 ◽  
Author(s):  
Matthew C Stubbs ◽  
InSung Min ◽  
Marc W Izzo ◽  
Ravikumar Rallapalli ◽  
Assia Derfoul ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Transcription Factor ◽  
Slow Growth ◽  
Chemotherapeutic Agent ◽  
S Phase ◽  
G1 Arrest ◽  
Zinc Finger Transcription Factor ◽  
Protein Levels ◽  
Myc Gene ◽  
Growth Suppressor

ZF87/MAZ is a zinc finger transcription factor that activates expression of tissue-specific genes and represses expression of the c-myc proto-oncogene. Infection of NIH3T3 fibroblasts with a retrovirus expressing ZF87/MAZ leads to a significant reduction in G418-resistant colonies, compared to cells infected with a retroviral control. Further, only a small fraction of the G418-resistant colonies express ZF87/MAZ. When the ZF87/MAZ-expressing colonies are expanded, they demonstrate a slow growth phenotype, a delayed transit through G1 phase and a decrease in endogenous c-myc gene expression and cyclin A and cyclin E protein levels. Consistent with a partial G1 arrest, the ZF87/MAZ-expressing cells show a reduced sensitivity to the S phase specific chemotherapeutic agent camptothecin. These data indicate that ZF87/MAZ is a growth suppressor protein in nontransformed cells, in part, by affecting the levels of key cell cycle regulatory proteins.Key words: cell cycle, ZF87/MAZ, cancer.

ATL

2014 ◽  
Vol 24 (7) ◽  
pp. 1165-1172 ◽  
Author(s):  
Xiaolong Liang ◽  
Yi Liu ◽  
Liqiong Zeng ◽  
Chao Yu ◽  
Zhongwen Hu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Cell Cycle ◽  
Cervical Cancer ◽  
Web Sites ◽  
S Phase ◽  
Luciferase Reporter ◽  
Reporter Assay ◽  
Chain Reaction ◽  
Protein Levels ◽  
Polymerase Chain

ObjectivesThe chief objective of this study was to identify the miRNAs targeting Fos, a well-recognized proto-oncogene that is commonly overexpressed in cervical cancer, and its biological significance on the cellular behaviors of HeLa, a cervical cancer cell.Materials and MethodsWe initially analyzed the 3′untranslated region (3′UTR) of Fos and screened the potential miRNAs targeting Fos using 3 bioinformatical Web sites. Luciferase reporter assay, real-time polymerase chain reaction, and Western blotting were used to validate the binding of chosen miRNA (miR-101) on the 3′UTR of Fos and the downstream regulation on its mRNA and protein levels. Furthermore, flow cytometry along with the Fos rescue strategy was applied to analyze the modulation of cell cycle of HeLa cells by miR-101.ResultsAmong these predicted candidate miRNAs, miR-101 was the miRNAs preferred by all the 3 used Web sites. The results of luciferase reporter assay, real-time polymerase chain reaction, and Western blotting demonstrated that miR-101 directly targeted on the 3′UTR of Fos and down-regulated the expression of Fos at mRNA and protein levels. Furthermore, cell cycle analysis showed that miR-101 arrests G1-to-S phase transition of HeLa cells, at least partially by targeting Fos.ConclusionsWe concluded that by targeting the proto-oncogene Fos, miR-101 is involved in G1-to-S phase transition in cervical cancer cells in vitro and might provide a new approach for the pharmacological interference node in cervical cancer treatment.

scholarly journals Disruption of the Rb-Raf-1 Interaction Inhibits Tumor Growth and Angiogenesis

2004 ◽  
Vol 24 (21) ◽  
pp. 9527-9541 ◽  
Author(s):  
Piyali Dasgupta ◽  
Jiazhi Sun ◽  
Sheng Wang ◽  
Gina Fusaro ◽  
Vicki Betts ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Growth Factor ◽  
Cell Cycle Progression ◽  
S Phase ◽  
Mitogen Activated Protein Kinase ◽  
Tubule Formation ◽  
Cycle Progression ◽  
Cyclin Dependent Kinases ◽  
Quiescent Cells ◽  
Stimulation Of

ABSTRACT The retinoblastoma tumor suppressor protein (Rb) plays a vital role in regulating mammalian cell cycle progression and inactivation of Rb is necessary for entry into S phase. Rb is inactivated by phosphorylation upon growth factor stimulation of quiescent cells, facilitating the transition from G1 phase to S phase. Although the signaling events after growth factor stimulation have been well characterized, it is not yet clear how these signals contact the cell cycle machinery. We had found previously that growth factor stimulation of quiescent cells lead to the direct binding of Raf-1 kinase to Rb, leading to its inactivation. Here we show that the Rb-Raf-1 interaction occurs prior to the activation of cyclin and/or cyclin-dependent kinases and facilitates normal cell cycle progression. Raf-1-mediated inactivation of Rb is independent of the mitogen-activated protein kinase cascade, as well as cyclin-dependent kinases. Binding of Raf-1 seemed to correlate with the dissociation of the chromatin remodeling protein Brg1 from Rb. Disruption of the Rb-Raf-1 interaction by a nine-amino-acid peptide inhibits Rb phosphorylation, cell proliferation, and vascular endothelial growth factor-mediated capillary tubule formation. Delivery of this peptide by a carrier molecule led to a 79% reduction in tumor volume and a 57% reduction in microvessel formation in nude mice. It appears that Raf-1 links mitogenic signaling to Rb and that disruption of this interaction could aid in controlling proliferative disorders.

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