title: Knockdown endogenous CypA with siRNA in U2OS cells results in disruption of F-actin structure and alters tumor phenotype.
abstract: Cyclophilin A (CypA) was originally identified as a cytosolic protein possessing peptidyl-prolyl isomerase activity. CypA has been shown to play a pivotal role in the immune response, but little is known about other molecular mechanisms of CypA-mediated biologic events. In our present study, we demonstrate that knockdown CypA expression using RNAi in U2OS cells resulted in disruption of the F-actin structure, as well as decreased anchorage-independent growth, proliferation, and migration. Wild-type U2OS cells treated with cyclosporine A (CsA), a peptidyl-prolyl isomerase inhibitor, displayed the same phenotype as knockdown CypA cells, suggesting that the isomerase activity of CypA is required to maintain a normal phenotype. In vitro and in vivo binding assays revealed that CypA binds to N-WASP, which functions in the nucleation of actin via the Arp2/3 complex. Pulse-chase labeling study indicated an enhanced degradation of N-WASP in cell lacking CypA, suggesting that CypA is required for stabilizing N-WASP to form a N-WASP/Arp2/3 complex for the nucleation/initiation of F-actin polymerization.
authors.affiliation: Dental Research Institute, UCLA School of Dentistry, Los Angeles, CA 90095, USA.
authors.forename: Colonya C
authors.initials: CC
authors.lastname: Calhoun
authors.forename: Ying-Chun
authors.initials: YC
authors.lastname: Lu
authors.forename: Jun
authors.initials: J
authors.lastname: Song
authors.forename: Robert
authors.initials: R
authors.lastname: Chiu
mesh_terms: D000199:Actins / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D021984:Cyclophilin A / Q000235:genetics / Q000378:metabolism; D055785:Gene Knockdown Techniques; D020868:Gene Silencing; D006801:Humans; D009369:Neoplasms / Q000378:metabolism / Q000473:pathology; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal / Q000235:genetics / Q000378:metabolism
chemical_list: D000199:Actins; D034741:RNA, Small Interfering; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal; D021984:Cyclophilin A