scholarly journals Proliferation-dependent and cell cycle–regulated transcription of mouse pericentric heterochromatin

2007 ◽  
Vol 179 (3) ◽  
pp. 411-421 ◽  
Author(s):  
Junjie Lu ◽  
David M. Gilbert
Keyword(s):  
Cell Cycle ◽  
Rna Polymerase Ii ◽  
Cellular Proliferation ◽  
Kinase Inhibitor ◽  
Pericentric Heterochromatin ◽  
Repeat Sequence ◽  
G1 Phase ◽  
Satellite Repeat ◽  
Cyclin Dependent Kinase Inhibitor ◽  
Quiescent Cells

Pericentric heterochromatin transcription has been implicated in Schizosaccharomyces pombe heterochromatin assembly and maintenance. However, in mammalian systems, evidence for such transcription is inconsistent. We identify two populations of RNA polymerase II–dependent mouse γ satellite repeat sequence–derived transcripts from pericentric heterochromatin that accumulate at different times during the cell cycle. A small RNA species was synthesized exclusively during mitosis and rapidly eliminated during mitotic exit. A more abundant population of large, heterogeneous transcripts was induced late in G1 phase and their synthesis decreased during mid S phase, which is coincident with pericentric heterochromatin replication. In cells that lack the Suv39h1,2 methyltransferases responsible for H3K9 trimethylation, transcription occurs from more sites but is still cell cycle regulated. Transcription is not detected in quiescent cells and induction during G1 phase is sensitive to serum deprivation or the cyclin-dependent kinase inhibitor roscovatine. We demonstrate that mammalian pericentric heterochromatin transcription is linked to cellular proliferation. Our data also provide an explanation for inconsistencies in the detection of such transcripts in different systems.

scholarly journals CCNE1 and E2F1 Partially Suppress G1 Phase Arrest Caused by Spliceostatin A Treatment

2021 ◽  
Vol 22 (21) ◽  
pp. 11623
Author(s):  
Kei Kikuchi ◽  
Daisuke Kaida
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Kinase Inhibitor ◽  
G1 Phase ◽  
Cell Cycle Regulators ◽  
Protein Levels ◽  
Cyclin Dependent Kinase Inhibitor ◽  
Phase Arrest ◽  
G1 Phase Arrest ◽  
Spliceostatin A

The potent splicing inhibitor spliceostatin A (SSA) inhibits cell cycle progression at the G1 and G2/M phases. We previously reported that upregulation of the p27 cyclin-dependent kinase inhibitor encoded by CDKN1B and its C-terminal truncated form, namely p27*, which is translated from CDKN1B pre-mRNA, is one of the causes of G1 phase arrest caused by SSA treatment. However, the detailed molecular mechanism underlying G1 phase arrest caused by SSA treatment remains to be elucidated. In this study, we found that SSA treatment caused the downregulation of cell cycle regulators, including CCNE1, CCNE2, and E2F1, at both the mRNA and protein levels. We also found that transcription elongation of the genes was deficient in SSA-treated cells. The overexpression of CCNE1 and E2F1 in combination with CDKN1B knockout partially suppressed G1 phase arrest caused by SSA treatment. These results suggest that the downregulation of CCNE1 and E2F1 contribute to the G1 phase arrest induced by SSA treatment, although they do not exclude the involvement of other factors in SSA-induced G1 phase arrest.

scholarly journals Inhibitory Effects of Peptide Lunasin in Colorectal Cancer HCT-116 Cells and Their Tumorsphere-Derived Subpopulation

2020 ◽  
Vol 21 (2) ◽  
pp. 537 ◽  
Author(s):  
Samuel Fernández-Tomé ◽  
Fei Xu ◽  
Yanhui Han ◽  
Blanca Hernández-Ledesma ◽  
Hang Xiao
Keyword(s):  
Colorectal Cancer ◽  
Cell Cycle ◽  
Kinase Inhibitor ◽  
G1 Phase ◽  
Inhibitory Effects ◽  
Cyclin Dependent Kinase Inhibitor ◽  
Hct 116 ◽  
Hct 116 Cells ◽  
Induced Apoptosis ◽  
Chemopreventive Activity

The involvement of cancer stem-like cells (CSC) in the tumor pathogenesis has profound implications for cancer therapy and chemoprevention. Lunasin is a bioactive peptide from soybean and other vegetal sources with proven protective activities against cancer and other chronic diseases. The present study focused on the cytotoxic effect of peptide lunasin in colorectal cancer HCT-116 cells, both the bulk tumor and the CSC subpopulations. Lunasin inhibited the proliferation and the tumorsphere-forming capacity of HCT-116 cells. Flow cytometry results demonstrated that the inhibitory effects were related to apoptosis induction and cell cycle-arrest at G1 phase. Moreover, lunasin caused an increase in the sub-GO/G1 phase of bulk tumor cells, linked to the apoptotic events found. Immunoblotting analysis further showed that lunasin induced apoptosis through activation of caspase-3 and cleavage of PARP, and could modulate cell cycle progress through the cyclin-dependent kinase inhibitor p21. Together, these results provide new evidence on the chemopreventive activity of peptide lunasin on colorectal cancer by modulating both the parental and the tumorsphere-derived subsets of HCT-116 cells.

scholarly journals Role of the UBL-UBA Protein KPC2 in Degradation of p27 at G1 Phase of the Cell Cycle

2005 ◽  
Vol 25 (21) ◽  
pp. 9292-9303 ◽  
Author(s):  
Taichi Hara ◽  
Takumi Kamura ◽  
Shuhei Kotoshiba ◽  
Hidehisa Takahashi ◽  
Kenichiro Fujiwara ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Ubiquitin Ligase ◽  
Kinase Inhibitor ◽  
26S Proteasome ◽  
G1 Phase ◽  
Cyclin Dependent Kinase ◽  
Cyclin Dependent Kinase Inhibitor ◽  
Uba Domain

ABSTRACT KPC2 (Kip1 ubiquitylation-promoting complex 2) together with KPC1 forms the ubiquitin ligase KPC, which regulates degradation of the cyclin-dependent kinase inhibitor p27 at the G1 phase of the cell cycle. KPC2 contains a ubiquitin-like (UBL) domain, two ubiquitin-associated (UBA) domains, and a heat shock chaperonin-binding (STI1) domain. We now show that KPC2 interacts with KPC1 through its UBL domain, with the 26S proteasome through its UBL and NH2-terminal UBA domains, and with polyubiquitylated proteins through its UBA domains. The association of KPC2 with KPC1 was found to stabilize KPC1 in a manner dependent on the STI1 domain of KPC2. KPC2 mutants that lacked either the NH2-terminal or the COOH-terminal UBA domain supported the polyubiquitylation of p27 in vitro, whereas a KPC2 derivative lacking the STI1 domain was greatly impaired in this regard. Depletion of KPC2 by RNA interference resulted in inhibition of p27 degradation at the G1 phase, and introduction of KPC2 derivatives into the KPC2-depleted cells revealed that the NH2-terminal UBA domain of KPC2 is essential for p27 degradation. These observations suggest that KPC2 cooperatively regulates p27 degradation with KPC1 and that the STI1 domain as well as the UBL and UBA domains of KPC2 are indispensable for its function.

Paradoxical accumulation of the cyclin-dependent kinase inhibitor p27kip1 during the cAMP-dependent mitogenic stimulation of thyroid epithelial cells

1996 ◽  
Vol 109 (7) ◽  
pp. 1759-1764
Author(s):  
F. Depoortere ◽  
J.E. Dumont ◽  
P.P. Roger
Keyword(s):  
Cell Cycle ◽  
Epithelial Cells ◽  
Cell Cycle Progression ◽  
Kinase Inhibitor ◽  
Concomitant Administration ◽  
Growth Stimulation ◽  
Positive Control ◽  
Cycle Progression ◽  
Cyclin Dependent Kinase Inhibitor ◽  
Enhanced Expression

In different systems, cAMP either blocks or promotes cell cycle progression in mid to late G1 phase. Dog thyroid epithelial cells in primary culture constitute a model of positive control of DNA synthesis initiation and G0-S pre-replicative phase progression by cyclic AMP (cAMP) as a second messenger for thyrotropin (TSH). We report here that TSH markedly increases the expression of p27kip1, the inhibitor of the cell cycle and cyclin-dependent kinases. This effect was prevented by the concomitant administration of the cAMP-independent mitogens, epidermal growth factor (EGF)+serum. EGF+serum also slightly inhibited the weak basal accumulation of p27kip1. Nevertheless, in the case of stimulation by TSH alone, the cAMP-dependent cell cycle progression was fully compatible with the enhanced expression of p27kip1. This observation is paradoxical since a decrease of p27kip1 is generally associated with growth stimulation in other systems, and since a similar cAMP-dependent increase of p27kip1 in macrophages has been found responsible for mid-G1 cell cycle arrest. The opposite regulation of p27kip1 in response to TSH or EGF+serum in dog thyroid epithelial cells suggests a major difference at mid to late G1 stages between cAMP-dependent and cAMP-independent mitogenic pathways.

p21WAF1 Control of Epithelial Cell Cycle and Cell Fate

2002 ◽  
Vol 13 (6) ◽  
pp. 453-464 ◽  
Author(s):  
Wendy C. Weinberg ◽  
Mitchell F. Denning
Keyword(s):  
Cell Cycle ◽  
Epithelial Cell ◽  
Cell Fate ◽  
Cell Biology ◽  
Kinase Inhibitor ◽  
Growth Arrest ◽  
Nuclear Antigen ◽  
Central Position ◽  
Cyclin Dependent Kinase ◽  
Cyclin Dependent Kinase Inhibitor

As a broad-acting cyclin-dependent kinase inhibitor, p21WAF1 occupies a central position in the cell cycle regulation of self-renewing tissues such as oral mucosa and skin. In addition to regulating normal cell cycle progression decisions, p21WAF1 integrates genotoxic insults into growth arrest and apoptotic signaling pathways that ultimately determine cell fate. As a result of its complex interactions with cell cycle machinery and response to mutagenic agents, p21WAF1 also has stage-specific roles in epithelial carcinogenesis. Finally, a view is emerging of p21WAF1 as not merely a cyclin-dependent kinase inhibitor, but also as a direct participant in regulating genes involved in growth arrest, senescence, and aging, thus providing an additional layer of control over matters of the cell cycle. This review discusses these various roles played by p21WAF1 in cell cycle control, and attempts to relate these to epithelial cell biology, with special emphasis on keratinocytes. (Abbreviations used include the following: Brdu, 5-Bromo-2-deoxyuridine; cdk, cyclin-dependent kinase; EGF, epidermal growth factor; KIP, kinase inhibitor protein; PCNA, proliferating cell nuclear antigen; and TPA, 12-O-tetradecanoylphorbol-13-acetate.)

scholarly journals Epstein-Barr Virus Nuclear Antigen 3A Promotes Cellular Proliferation by Repression of the Cyclin-Dependent Kinase Inhibitor p21WAF1/CIP1

2014 ◽  
Vol 10 (10) ◽  
pp. e1004415 ◽  
Author(s):  
Melissa L. Tursiella ◽  
Emily R. Bowman ◽  
Keith C. Wanzeck ◽  
Robert E. Throm ◽  
Jason Liao ◽  
...  
Keyword(s):  
Epstein Barr Virus ◽  
Cellular Proliferation ◽  
Kinase Inhibitor ◽  
Nuclear Antigen ◽  
Cyclin Dependent Kinase ◽  
Barr Virus ◽  
Cyclin Dependent Kinase Inhibitor ◽  
Epstein Barr

scholarly journals A comprehensive model for the proliferation–quiescence decision in response to endogenous DNA damage in human cells

2018 ◽  
Vol 115 (10) ◽  
pp. 2532-2537 ◽  
Author(s):  
Frank S. Heldt ◽  
Alexis R. Barr ◽  
Sam Cooper ◽  
Chris Bakal ◽  
Béla Novák
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Kinase Inhibitor ◽  
Human Cells ◽  
Cyclin Dependent Kinase ◽  
Restriction Point ◽  
Cyclin Dependent Kinase Inhibitor ◽  
Serum Stimulation ◽  
G1 Cells ◽  
External Stimuli

Human cells that suffer mild DNA damage can enter a reversible state of growth arrest known as quiescence. This decision to temporarily exit the cell cycle is essential to prevent the propagation of mutations, and most cancer cells harbor defects in the underlying control system. Here we present a mechanistic mathematical model to study the proliferation–quiescence decision in nontransformed human cells. We show that two bistable switches, the restriction point (RP) and the G1/S transition, mediate this decision by integrating DNA damage and mitogen signals. In particular, our data suggest that the cyclin-dependent kinase inhibitor p21 (Cip1/Waf1), which is expressed in response to DNA damage, promotes quiescence by blocking positive feedback loops that facilitate G1 progression downstream of serum stimulation. Intriguingly, cells exploit bistability in the RP to convert graded p21 and mitogen signals into an all-or-nothing cell-cycle response. The same mechanism creates a window of opportunity where G1 cells that have passed the RP can revert to quiescence if exposed to DNA damage. We present experimental evidence that cells gradually lose this ability to revert to quiescence as they progress through G1 and that the onset of rapid p21 degradation at the G1/S transition prevents this response altogether, insulating S phase from mild, endogenous DNA damage. Thus, two bistable switches conspire in the early cell cycle to provide both sensitivity and robustness to external stimuli.

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