Human diploid fibroblasts (HDFs) exposed to subcytotoxic stress display many features of senescence. Using differential display RT-PCR, gene expression of HDFs in premature senescence induced by tert-butylhydroperoxide or ethanol and in replicative senescence was compared to gene expression of HDFs at early cumulative population doublings. Thirty genes of known function were identified from the 265 differentially displayed cDNA fragments. A customized low-density array allowed to confirm the relative level of the corresponding 30 transcripts. We found differential expression of genes coding for proteins implicated namely in growth arrest (PTEN, IGFBP-3, LRP-1 and CAV1), senescent morphogenesis (TGFb1 and LOXL2) and iron metabolism (TFR and FTL).
Treatment of IMR-90 human diploid fibroblasts with a sublethal concentration of H 2 O 2 induces premature senescence. We investigated the protein abundance, subcellular localization and involvement of caveolin 1 in premature senescence. Caveolin 1 is a scaffolding protein able to concentrate and organize signaling molecules within the caveolae membrane domains. We report the first evidence of increased nuclear and cytoplasmic localization of caveolin 1 during establishment of H 2 O 2 -induced premature senescence. Moreover, we demonstrate that phosphorylation of caveolin 1 during treatment with H 2 O 2 is dependent on p38a mitogen-activated protein kinase.
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