A cryptopromoter is activated in the proliferating cell nuclear antigen gene of growth arrested cells

Sell, Christian; Chang, Chung-Ming; Koniecki, Janice; Chen, Huimin; Baserga, Renato

doi:10.1002/jcp.1041520122

Cited by 9 publications

(5 citation statements)

References 28 publications

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“…Expression of the PCNA gene is also decreased in senescent WI-38 fibroblast cells and is regulated by posttranscriptional mechanisms [Chang et al, 1990;Sell et al, 1992]. The PCNA hnRNA is present in senescent cells at levels comparable to that in proliferating cells.…”

Section: Discussionmentioning

confidence: 83%

“…However, similar to EPC-1, PCNA mRNA levels are undetectable in senescent WI-38 fibroblasts [Chang et al, 1991] whereas the hnRNA is readily detected using RT-PCR. Under some conditions, the changes in PCNA hnRNA levels are regulated by changes in stability [Sell et al, 1992]. Both EPC-1 and PCNA hnRNA are regulated during replicative senescence, and it is possible that a common mechanism may be involved.…”

Section: Discussionmentioning

confidence: 99%

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Regulation ofEPC-1/PEDF in normal human fibroblasts is posttranscriptional

et al. 2000

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The EPC-1 (early population doubling level cDNA-1) gene, also known as pigment epithelium-derived factor, encodes a protein belonging to the serine protease inhibitor (serpin) superfamily that has been reported to inhibit angiogenesis and proliferation of several cell types. We have previously reported that the EPC-1 mRNA and the secreted EPC-1 protein are expressed at levels more than 100-fold higher in early passage, G(0), WI-38 cells compared to either proliferating or senescent WI-38 fibroblasts. To examine the molecular mechanisms that regulate changes in EPC-1 gene expression in WI-38 cells, we isolated and characterized the human EPC-1 gene and determined the mRNA cap site. Transcriptional assays showed no change in the transcription rates of EPC-1 between young proliferating, quiescent, and senescent WI-38 cells. These results suggest posttranscriptional regulation of the EPC-1 gene. Reverse transcriptase polymerase chain reaction measurements (of hnRNA) indicate regulation at the hnRNA level. The regulation of the EPC-1 gene at the level of hnRNA can explain the observed slow increase in the steady-state EPC-1 mRNA levels when cells become quiescent. The reduction of EPC-1 mRNA levels that occurs when cells exit G(0) and are induced to proliferate can be accounted for by a reduction of the EPC-1 mRNA stability in stimulated cells as compared to quiescent cells.

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Section: Discussionmentioning

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Regulation ofEPC-1/PEDF in normal human fibroblasts is posttranscriptional

et al. 2000

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“…Previously, both transcriptional as well as posttranscriptional components in the regulation of PCNA mRNA levels after serum stimulation have been reported (1,37,46). Therefore, we next incubated S phase nuclei with S phase cytoplasmic extract in the presence of the transcriptional inhibitor actinomycin D or the translational inhibitor cycloheximide.…”

Section: Resultsmentioning

confidence: 99%

p21^CIP1 Controls Proliferating Cell Nuclear Antigen Level in Adult Cardiomyocytes

Engel

Hauck

Boehm

et al. 2003

Molecular and Cellular Biology

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Cell cycle withdrawal associated with terminal differentiation is responsible for the incapability of many organs to regenerate after injury. Here, we employed a cell-free system to analyze the molecular mechanisms underlying cell cycle arrest in cardiomyocytes. In this assay, incubation of S phase nuclei mixed with cytoplasmic extract of S phase cells and adult primary cardiomyocytes results in a dramatic reduction of proliferating cell nuclear antigen (PCNA) protein levels. This effect was blocked by the proteasome inhibitors MG132 and lactacystin, whereas actinomycin D and cycloheximide had no effect. Immunodepletion and addback experiments revealed that the effect of cardiomyocyte extract on PCNA protein levels is maintained by p21 but not p27. In serum-stimulated cardiomyocytes PCNA expression was reconstituted, whereas the protein level of p21 but not that of p27 was reduced. Cytoplasmic extract of serum-stimulated cardiomyocytes did not influence the PCNA protein level in S phase nuclei. Moreover, the hypertrophic effect of serum stimulation was blocked by ectopic expression of p21 and the PCNA protein level was found to be upregulated in adult cardiomyocytes derived from p21 knockout mice. Our data provide evidence that p21 regulates the PCNA protein level in adult cardiomyocytes, which has implications for cardiomyocyte growth control.The idea of eliciting tissue repair by regenerative growth has incited concerted effort within the past decade aimed at the identification of mechanisms which maintain cell cycle arrest in terminally differentiated cells. Progression of eukaryotic cells through the cell cycle is controlled by the specific activation of a series of cyclin-dependent kinases (cdk's) (38). cdk's are known to phosphorylate tumor suppressor pocket proteins (Rb, p107, and p130), resulting in a release of E2F transcription factors and thus enabling the transcription of E2F-dependent genes required for S phase entry (15). One mechanism that downregulates the activity of cdk's leading to cell cycle arrest involves the binding of inhibitory proteins. Cyclin/cdk complexes are regulated by two families of cdk inhibitors (cki's), the INK4 family and the CIP/KIP family, including p21 and p27. INK4 proteins and CIP/KIP proteins are structurally distinct and interact with cyclins and cdk's in different ways. Whereas members of the INK4 family specifically inhibit cdk4 and cdk6, members of the CIP/KIP family are general inhibitors of cdk's involved in the G 1 /S transition and S phase (36, 49). Furthermore, p21 and p27 are involved in the differentiation of intestinal epithelial cells, keratinocytes, PC12 cells, glioma cells, and skeletal and cardiac muscle cells (53). The biochemical activities of cki's and their ability to promote differentiation implicate these proteins as mediators of cell cycle exit and differentiation. However, it is unclear why p21 and p27 are highly expressed in most differentiated cells, while cdk's as their main targets are downregulated.In a previous study we established a new my...

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“…Thus, additional important regulatory sequences must reside within the gene outside the promoter and the first intron. A cryptic promoter was previously identified in intron 4 of the gene (86); its presence seems to be required for the proper regulation of PCNA mRNA in G 0 cells (8,87). In addition, an antisense transcript, 500 -600 bases in length with an unknown function, was reported to be constitutively synthesized from a promoter located within the first intron (11).…”

Section: Proper Cell Cycle-dependent Regulation Of Hpcna Expression Imentioning

confidence: 99%

The Promoter of the Human Proliferating Cell Nuclear Antigen Gene Is Not Sufficient for Cell Cycle-dependent Regulation in Organotypic Cultures of Keratinocytes

Noya¹,

Chien²,

Wu³

et al. 2002

Journal of Biological Chemistry

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The proliferating cell nuclear antigen (PCNA) is essential for DNA replication of mammalian cells and their small DNA tumor viruses. The mechanism of the cell cycle-dependent regulation of the human PCNA promoter is not clear despite extensive investigations. In this report, we employed organotypic cultures of primary human keratinocytes, which closely resemble native skin comprising both proliferating and postmitotic, differentiated cells, to examine the cell cycle-dependent regulation of the human PCNA gene (hPCNA) in the absence or presence of the human papillomavirus type 18 (HPV-18) E7 protein. HPV-18 E7 promotes S phase re-entry in post-mitotic differentiated keratinocytes by abrogating the transcription repression of E2F transcription factors by the retinoblastoma susceptibility protein, pRb. We demonstrated that E7 reactivated the transcription of the endogenous hPCNA in differentiated keratinocytes. In contrast, with or without E7, the expression of a transduced hPCNA promoter-driven reporter did not correlate with that of the endogenous hPCNA gene in either proliferating or differentiated cells. Moreover, in Chinese hamster ovary and L-cells, HPV E7 and the adenovirus E1A protein repressed the transduced hPCNA promoter, but both activated an extended promoter construct spanning the first intron. Mutations of two E2F sites in the intron reduced the basal activity and abolished the response to E7 or E1A. Promoter repression or activation required the CR2 domain of E7 and, to a lesser extent, CR1 as well. However, in organotypic cultures, this extended promoter construct failed to recapitulate the cell cycle-dependent regulation of the endogenous hPCNA gene. Only when a full-length Myc-tagged hPCNA spanning the 5 promoter and all exons and introns was used was the native pattern of expression largely restored, indicative of the complexity of its regulation.

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A cryptopromoter is activated in the proliferating cell nuclear antigen gene of growth arrested cells

Cited by 9 publications

References 28 publications

Regulation ofEPC-1/PEDF in normal human fibroblasts is posttranscriptional

Regulation ofEPC-1/PEDF in normal human fibroblasts is posttranscriptional

p21^CIP1 Controls Proliferating Cell Nuclear Antigen Level in Adult Cardiomyocytes

The Promoter of the Human Proliferating Cell Nuclear Antigen Gene Is Not Sufficient for Cell Cycle-dependent Regulation in Organotypic Cultures of Keratinocytes

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A cryptopromoter is activated in the proliferating cell nuclear antigen gene of growth arrested cells

Cited by 9 publications

References 28 publications

Regulation ofEPC-1/PEDF in normal human fibroblasts is posttranscriptional

Regulation ofEPC-1/PEDF in normal human fibroblasts is posttranscriptional

p21CIP1 Controls Proliferating Cell Nuclear Antigen Level in Adult Cardiomyocytes

The Promoter of the Human Proliferating Cell Nuclear Antigen Gene Is Not Sufficient for Cell Cycle-dependent Regulation in Organotypic Cultures of Keratinocytes

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p21^CIP1 Controls Proliferating Cell Nuclear Antigen Level in Adult Cardiomyocytes