title: Novel expression of CST1 as candidate senescence marker.
abstract: Senescent cells exhibit altered expression of numerous genes. Identifying the significance of the changes in gene expression may help advance our understanding of the senescence biology. Here, we report on the consistent and strong upregulation of CST1 expression during cellular senescence, independent of the initial trigger. CST1 expression at both the messenger RNA and protein levels was barely detected in control cells, which included early passage proliferating, quiescent, or immortal human fibroblasts and various human tumor cell lines. Immunoblotting and immunofluorescence cytochemical studies further suggest that CST1 accumulates intracellularly, within vesicular structures. We discuss these results in light of the known function of CST1 as a potent inhibitor of lysosomal cysteine proteases.
authors.affiliation: Department of Biological Sciences, College of Pharmacy, Touro University of California, Mare Island, Vallejo, USA. daniel.keppler@tu.edu
authors.forename: Daniel
authors.initials: D
authors.lastname: Keppler
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.forename: Teeru
authors.initials: T
authors.lastname: Bihani
authors.forename: Athena W
authors.initials: AW
authors.lastname: Lin
mesh_terms: D000375:Aging / Q000235:genetics* / Q000473:pathology; D015415:Biomarkers / Q000378:metabolism; D015153:Blotting, Western; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000235:genetics*; D004591:Electrophoresis, Polyacrylamide Gel; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D012313:RNA / Q000235:genetics*; D055333:Salivary Cystatins / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D015415:Biomarkers; C525171:CST1 protein, human; D055333:Salivary Cystatins; D012313:RNA