Increased abundance of cytoplasmic and nuclear caveolin 1 in human diploid fibroblasts in H₂O₂-induced premature senescence and interplay with p38α^MAPK

Abstract 

Treatment of IMR-90 human diploid fibroblasts with a sublethal concentration of H₂O₂ 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 H₂O₂-induced premature senescence. Moreover, we demonstrate that phosphorylation of caveolin 1 during treatment with H₂O₂ is dependent on p38α mitogen-activated protein kinase.

Abbreviations: FBS, fetal bovine serum, GAPDH, glyceraldehyde-3-phosphate dehydrogenase, HDF, human diploid fibroblast, IgG, immunoglobulin G, MAPK, mitogen-activated kinase, MEM, minimum essential medium, mRNA, messenger ribonucleic acid, MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assay, PBS, phosphate buffer saline, RT-PCR, reverse transcriptase-polymerase chain reaction, S.D., standard deviation, SA β-gal activity, senescence associated-β galactosidase activity, siRNA, small interfering RNA, TGF-β1, transforming growth factor-β1

Keywords: H₂O₂, siRNA, Cellular senescence, Caveolin 1, Fibroblasts, Stress-induced premature senescence