Abstract of related literatures |
1. Proliferating cell nuclear antigen (PCNA) RNA levels are regulated by transcription as well as changes in stability, in growing cells. We have cloned the murine PCNA cDNA and a fragment of the murine PCNA gene flanking the transcription initiation site. Comparison of the murine deduced amino acid sequence with the PCNA sequence from rat, human, Drosophila, Saccharomyces cerevisiae, and higher plants, reveals extensive homology between species. The homology is likely to be related to the fundamental role of PCNA as an auxiliary protein for DNA replication. Consensus sequences for transcriptional regulatory factors identified within 520 bp 5' of the cap site of the murine PCNA gene include: an inverted CCAAT site, an enhancer core element (EBP-1), three cAMP-response elements (CRE-BP), one AP-2 site, three Sp1 sites, and two octamer sequences. The first 20 bp of the transcriptional unit are homologous to an initiator element, which may direct transcription from RNA polymerase II in the absence of a TATAA box. The consensus elements in the murine PCNA gene are similar in sequence and/or location to elements identified in the genes for human, Drosophilia, and yeast PCNA. PMID: [1726365]
2. We have isolated clones containing the entire mouse proliferating cell nuclear antigen (PCNA) gene of 3890 bp and flanking sequences using a rat PCNA cDNA as a probe. The mouse gene has 6 exons whose sequences and junction points of exons with introns are extensively homologous to the human gene while sizes and nucleotide sequences of introns are much less conserved than exons. By a transient expression assay of chloramphenicol acetyltransferase, the promoter of this gene is localized within 200 bp upstream of the transcription initiation site. We have also isolated two processed pseudogenes. Homology between the first one (psi PCNA-I) and the exons of the PCNA gene was 76.8% in the region so far sequenced. The second one (psi PCNA-II) consists of a region highly homologous to the entire exons of the PCNA gene, and only 9 out of total 1256 bp are different from the corresponding exon sequence of the gene. The 5'-flanking region of the psi PCNA-II did not function as an active promoter. Surveys in various wild and laboratory mice genomes suggest that the psi PCNA-II was generated through the reverse transcription process of the PCNA mRNA about 5 x 10(5) years ago in the domesticus subspecies of Mus musculus, the house mouse. The psi PCNA-II is tentatively mapped in the chromosome 17 of the C57BL mouse. PMID: [1674997]
3. The National Institutes of Health's Mammalian Gene Collection (MGC) project was designed to generate and sequence a publicly accessible cDNA resource containing a complete open reading frame (ORF) for every human and mouse gene. The project initially used a random strategy to select clones from a large number of cDNA libraries from diverse tissues. Candidate clones were chosen based on 5'-EST sequences, and then fully sequenced to high accuracy and analyzed by algorithms developed for this project. Currently, more than 11,000 human and 10,000 mouse genes are represented in MGC by at least one clone with a full ORF. The random selection approach is now reaching a saturation point, and a transition to protocols targeted at the missing transcripts is now required to complete the mouse and human collections. Comparison of the sequence of the MGC clones to reference genome sequences reveals that most cDNA clones are of very high sequence quality, although it is likely that some cDNAs may carry missense variants as a consequence of experimental artifact, such as PCR, cloning, or reverse transcriptase errors. Recently, a rat cDNA component was added to the project, and ongoing frog (Xenopus) and zebrafish (Danio) cDNA projects were expanded to take advantage of the high-throughput MGC pipeline. PMID: [15489334]
4. Expression of cyclin, a non-histone nuclear protein, during recombinant interleukin 2 (rIL2)-driven cell-cycle progression of cloned T lymphocytes has been assessed. We found that expression of cyclin protein, as detected by immunofluorescence, is tightly associated with proliferation, and not merely S-phase, of L2 cells stimulated with rIL2. Cyclin immunofluorescence was detected in all cell-cycle phases (G1/S/G2/M, as detected by flow cytometry) of proliferating L2 cells. Accumulation of cyclin mRNA levels was induced as early as 1 h after stimulation, was maximal at 25-49 h, and remained elevated throughout stimulation, as detected by Northern blot analysis. A cDNA-encoding murine cyclin was cloned from a cDNA library prepared from IL2-stimulated cloned T cells. The sequence of the 5' end of the murine cyclin cDNA was determined and found to be 88% and 82% similar to the sequences of cDNA clones encoding rat and human cyclin, respectively. The present studies demonstrate that cyclin protein and mRNA accumulation are highly regulated during IL2-induced proliferation of a cloned T cell. These data provide a framework for addressing the molecular mechanisms regulating cyclin gene expression during cellular proliferation. PMID: [2906640]
5. The herpes simplex virus (HSV) virulence factor ICP34.5, the mouse myeloid differentiation protein MyD116, and the hamster growth arrest and DNA damage protein GADD34 share a 63-amino-acid carboxyl domain which has significant homologies to otherwise divergent proteins. Here we report that both ICP34.5 and its cellular homolog MyD116 complex through the conserved domain with proliferating cell nuclear antigen. In addition, HSV infection induces a novel 70-kDa cellular protein detectable by antisera to both ICP34.5 and GADD34, demonstrating that this novel protein possesses homology with the 63-amino-acid conserved domain. PMID: [9371605]
6. We isolated a mouse cDNA encoding APEX2 protein and demonstrated that APEX2 binds to PCNA. The level of Apex2 mRNA was high in the thymus, bone marrow, spleen, and kidney in adult mice. Apex2 consists of six exons and is flanked on the 3' end by Alas2 on X chromosome 63.0. Furthermore, Apex2 is flanked on the 5' end by a novel gene with a 106-bp intergenic sequence. We disrupted Apex2 in embryonic stem cells derived from a male mouse, and a 55-kDa APEX2 protein was detected in the nuclei of Apex2(+) but not Apex2-disrupted cells. Immunoelectron microscopy revealed that APEX2 is also localized in the mitochondria of Apex2(+) cells. In serum-stimulated BALB/c 3T3 cells, the level of Apex2 mRNA was transiently increased and the level of APEX2 reached a maximum in the late S phase, thus indicating that APEX2 may participate in postreplicative base excision repair. PMID: [12573260]
7. The proliferating cell nuclear antigen (PCNA) is an essential protein for DNA replication and damage repair. How its function is controlled remains an important question. Here, we show that the chromatin-bound PCNA protein is phosphorylated on Tyr 211, which is required for maintaining its function on chromatin and is dependent on the tyrosine kinase activity of EGF receptor (EGFR) in the nucleus. Phosphorylation on Tyr 211 by EGFR stabilizes chromatin-bound PCNA protein and associated functions. Consistently, increased PCNA Tyr 211 phosphorylation coincides with pronounced cell proliferation, and is better correlated with poor survival of breast cancer patients, as well as nuclear EGFR in tumours, than is the total PCNA level. These results identify a novel nuclear mechanism linking tyrosine kinase receptor function with the regulation of the PCNA sliding clamp. PMID: [17115032]
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