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Identification of PITX1 as a TERT suppressor gene located on human chromosome 5.

ABSTRACT: Telomerase, a ribonucleoprotein enzyme that maintains telomere length, is crucial for cellular immortalization and cancer progression. Telomerase activity is attributed primarily to the expression of telomerase reverse transcriptase (TERT). Using microcell-mediated chromosome transfer (MMCT) into the mouse melanoma cell line B16F10, we previously found that human chromosome 5 carries a gene, or genes, that can negatively regulate TERT expression (H. Kugoh, K. Shigenami, K. Funaki, J. Barrett, and M. Oshimura, Genes Chromosome Cancer 36:37-47, 2003). To identify the gene responsible for the regulation of TERT transcription, we performed cDNA microarray analysis using parental B16F10 cells, telomerase-negative B16F10 microcell hybrids with a human chromosome 5 (B16F10MH5), and its revertant clones (MH5R) with reactivated telomerase. Here, we report the identification of PITX1, whose expression leads to the downregulation of mouse tert (mtert) transcription, as a TERT suppressor gene. Additionally, both human TERT (hTERT) and mouse TERT (mtert) promoter activity can be suppressed by PITX1. We show that three and one binding site within the hTERT and mtert promoters, respectively, that express a unique conserved region are responsible for the transcriptional activation of TERT. Furthermore, we showed that PITX1 binds to the TERT promoter both in vitro and in vivo. Thus, PITX1 suppresses TERT transcription through direct binding to the TERT promoter, which ultimately regulates telomerase activity.

SUBMITTER: Qi DL

PROVIDER: S-EPMC3126332 | biostudies-literature | 2011 Apr

REPOSITORIES: biostudies-literature

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Identification of PITX1 as a TERT suppressor gene located on human chromosome 5.

Qi Dong-Lai DL Ohhira Takahito T Fujisaki Chikako C Inoue Toshiaki T Ohta Tsutomu T Osaki Mitsuhiko M Ohshiro Eriko E Seko Tomomi T Aoki Shinsuke S Oshimura Mitsuo M Kugoh Hiroyuki H

Molecular and cellular biology 20110207 8

Telomerase, a ribonucleoprotein enzyme that maintains telomere length, is crucial for cellular immortalization and cancer progression. Telomerase activity is attributed primarily to the expression of telomerase reverse transcriptase (TERT). Using microcell-mediated chromosome transfer (MMCT) into the mouse melanoma cell line B16F10, we previously found that human chromosome 5 carries a gene, or genes, that can negatively regulate TERT expression (H. Kugoh, K. Shigenami, K. Funaki, J. Barrett, an ...[more]

PMID: 21300782

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Project description:The objective of Human Y Chromosome Proteome Project is to map and annotate all proteins encoded by genes on the MSY sequences. Lysine (K)-specific demethylase 5D (KDM5D) is located on the AZFb region of Y chromosome and encode for a JmjC-domain-containing protein. Changes in KDM5D transcript level in prostate cancer have shown in various studies. To investigation the function of KDM5D in prostate cancer, we knocked down the expression of KDM5D in human prostate cancer cell (DU-145) using siRNA approach. Down-regulation of KDM5D was confirmed by qRT-PCR and western-blot analyses. Cell cycle analysis and MTS assay revealed that down-regulation of KDM5D induces cell proliferation. Furthermore, we observed that KDM5D down-regulation could effectively decrease apoptosis, as measured by the propidium iodide flow cytometric assay. To further our study, we investigated the dynamic of KDM5D protein network using shotgun label free quantitative proteomics approach in knockdown and control cell line. In summary, 102 down-regulated and 107 up-regulated proteins were detected from 894 total proteins. Up-regulated proteins mainly activated ribosome biogenesis whereas down-regulated genes were mainly involved in proteolysis, cell death and metabolic process. The result raw files were converted to mzXML format and processed through the global proteome machine (GPM) software (version 2.1.1) of the X!Tandem algorithm (freely available at http://www.thegpm.org). The 16 gel fractions were processed serially for each experiment and the output files were generated as non-redundant, merged files with protein identifications with log (e) values less than -1, for each individual gel fraction. A protein database compiled from NCBI (Homo sapien) was used in GPM to search the tandem mass spectra; the database also included common trypsin and human peptide contaminants. False discovery rates (FDR) were evaluated by searching against a reversed sequence database. Search parameters included MS and MS/MS tolerances of +2 Da and +0.2 Da, carbamidomethylation of cysteine as fixed modifications, oxidation of methionine as variable modifications and tolerance of two missed tryptic cleavages and K/R-P cleavages.

Dataset Information

Identification of PITX1 as a TERT suppressor gene located on human chromosome 5.

Publications

Identification of PITX1 as a TERT suppressor gene located on human chromosome 5.

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