| The Catalytic Subunit of Human Telomerase is a Unique Caspase-6 and Caspase-7 Substrate. | |
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MedLine Citation:
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PMID: 21936563 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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Telomerase is a ribonucleoprotein complex that is essential for persistent cellular proliferation. The catalytic subunit of human telomerase, hTERT, functions as a reverse transcriptase and promotes vitality by maintaining telomeric DNA length. hTERT is tightly regulated with complex but poorly understood positive and negative regulation at several levels including transcription, protein-protein interactions, and post-translation modifications. Because evidence implicates hTERT as an apoptosis inhibitor and because telomerase activity tends to decrease during apoptosis, we hypothesized that hTERT is a caspase substrate leading to down regulation during apoptosis. Caspases are proteases that initiate and execute apoptosis by cleaving target proteins. Indeed, we found that caspases-6 and -7 cleave hTERT during apoptosis in cultured cells. Caspase-6 cleaves at residues D129 and D637 and caspase-7 cleaves at E286 and D628. Three of the caspase cleavage sites are unique motifs. All four caspase motifs appear conserved in TERTs from old world monkeys and apes, and the caspase-6 sites appear conserved in all primates. The caspase site that cleaves at D129 appears conserved in amniotes. hTERT fragments generated by cleavage were remarkably persistent, lasting hours after caspase activation. These results reveal a new biologically relevant mechanism for telomerase down regulation through caspase mediated cleavage of hTERT and expand the list of known caspase motifs. |
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Authors:
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Joana Soares; Margaret M Lowe; Michael Bruce Jarstfer |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-9-21 |
Journal Detail:
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Title: Biochemistry Volume: - ISSN: 1520-4995 ISO Abbreviation: - Publication Date: 2011 Sep |
Date Detail:
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Created Date: 2011-9-22 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0370623 Medline TA: Biochemistry Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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