title: Skp2-mediated degradation of p27 regulates cell cycle progression in compressed human bladder smooth muscle cells.
abstract: Bladder outlet obstruction (BOO) results in smooth muscle cell hyperplasia, decreased bladder wall compliance, and lower and upper urinary tract pathology. Mechanical stimulus on detrusor tissue is critical to BOO disease progression. Our previous studies confirm that mechanical stimulus triggers human bladder smooth muscle cell (HBSMC) proliferation. To better understand the signal transduction mechanisms for this process we detected cell cycle machinery of HBSMC (Bose ® Biodynamic, Minnetonka, MN, USA). HBSMCs cultured in scaffolds were subjected to four different pressures (0 cmH2O, 100 cmH2O, 200 cmH2O, and 300 cmH2O) for 24 hours, which were controlled by a BOSE BioDynamic bioreactor. Then we used flow cytometry to examine cell cycle distribution, polymerase chain reaction, and immunoblotting to quantify Skp2, p27, and p21 expression in each group. Additionally, Skp2 was silenced in HBSMCs using small interfering RNA to validate the role of Skp2 in mediating pressure-induced cell cycle progression. Compared with the 0 cmH2O control, HBSMCs in the 200 cmH2O and 300 cmH2O groups exhibited high-level expression of Skp2 gene and low-level expression of p27 protein. However, p21, another downstream signal of Skp2, showed no significant change between groups. In addition, Skp2 silencing abolished increases in cell proliferation induced by pressure. To the best of our knowledge, this is the first report on the functional importance of Skp2 in cyclic hydrodynamic pressure stimulated HBSMC proliferation. The signal transduction mechanism for this process involves p27 as well as p21 signaling pathway.
authors.affiliation: Department of Urology, West China Hospital, Sichuan University, Chengdu, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Chen
authors.affiliation: Department of Urology, West China Hospital, Sichuan University, Chengdu, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Wu
authors.affiliation: Department of Urology, West China Hospital, Sichuan University, Chengdu, China.
authors.forename: Tang-Qiang
authors.initials: TQ
authors.lastname: Wei
authors.affiliation: Department of Urology, West China Hospital, Sichuan University, Chengdu, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Wei
authors.affiliation: Key Laboratory of Transplant Engineering and Immunology, Ministry of Health, West China Hospital, Sichuan University, Chengdu, China.
authors.forename: Sheng-Fu
authors.initials: SF
authors.lastname: Li
authors.affiliation: Department of Urology, West China Hospital, Sichuan University, Chengdu, China. Electronic address: Wangkj139@yahoo.cn.
authors.forename: Kun-Jie
authors.initials: KJ
authors.lastname: Wang
authors.affiliation: Department of Urology, West China Hospital, Sichuan University, Chengdu, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Li
mesh_terms: D002453:Cell Cycle; D049109:Cell Proliferation; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D057446:Hydrodynamics; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000378:metabolism*; D011312:Pressure; D059748:Proteolysis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D044786:S-Phase Kinase-Associated Proteins / Q000378:metabolism*; D001743:Urinary Bladder / Q000166:cytology*
chemical_list: D050759:Cyclin-Dependent Kinase Inhibitor p21; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D044786:S-Phase Kinase-Associated Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27
keywords: Cell cycle; Cellular mechanotransduction; Mechanical stress; Urinary bladder; Urinary bladder neck obstruction