Clusterin/apolipoprotein J is a novel biomarker of cellular senescence that does not affect the proliferative capacity of human diploid fibroblasts.
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| Abstract |
Normal human fibroblasts have a limited replicative potential in culture and eventually reach a state of irreversible growth arrest, termed senescence. In a previous study aiming to identify genes that are differentially regulated during cellular senescence we have cloned clusterin/apolipoprotein J (Apo J), a 80 kDa secreted glycoprotein. In the current report we pursue our studies and show that senescence of human diploid fibroblasts is accompanied by up-regulation of both Apo J mRNA and protein levels, but with no altered biogenesis, binding partner profile or intracellular distribution of the two Apo J forms detected. To analyze the causal relationship between senescence and Apo J protein accumulation, we stably overexpressed the Apo J gene in primary as well as in SV40 T antigen-immortalized human fibroblasts and we showed no alteration of the proliferative capacity of the transduced cells. Despite previous reports on tumor-derived cell lines, overexpression of Apo J in human fibroblasts did not provide protection against apoptosis or growth arrest induced by hydrogen peroxide. Overall, our results suggest that Apo J overexpression does not induce senescence but it is rather a secondary consequence of the senescence phenotype. To our knowledge this is the first report that provides a functional analysis of human Apo J during replicative senescence.
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| Authors | C Petropoulou, I P Trougakos, E Kolettas, O Toussaint, E S Gonos |
| Journal | FEBS letters (FEBS Lett) Vol. 509 Issue 2 Pg. 287-97 (Dec 07 2001) ISSN: 0014-5793 [Print] England |
| PMID | 11741605 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't) |
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