title: Expression and proliferation profiles of PKC, JNK and p38MAPK in physiologically stretched human bladder smooth muscle cells.
abstract: OBJECTIVE
  To determine protein kinase C (PKC), c-Jun NH2-Terminal Kinase (JNK) and P38 mitogen-activated protein kinases (p38MAPK) expression levels and effects of their respective inhibitors on proliferation of human bladder smooth muscle cells (HBSMCs) when physiologically stretched in vitro.
  
  
  METHODS
  HBSMCs were grown on silicone membrane and stretch was applied under varying conditions; (equibiaxial elongation: 2.5%, 5%, 10%, 15%, 20%, 25%), (frequency: 0.05, 0.1, 0.2, 0.5, 1Hz). Optimal physiological stretch was established by assessing proliferation with 5-Bromo-2-deoxyuridine (BrdU) assay and flow cytometry. PKC, JNK and p38 expression levels were analyzed by Western blot. Specificity was maintained by employing specific inhibitors; (GF109203X for PKC, SP600125 for JNK and SB203580 for p38MAPK), in some experiments.
  
  
  RESULTS
  Optimum proliferation was observed at 5% equibiaxial stretch (BrdU: 0.837±0.026 (control) to 1.462±0.023)%, (P<0.05) and apoptotic cell death rate decreased from 16.4±0.21% (control) to 4.5±0.13% (P<0.05) applied at 0.1Hz. Expression of PKC was upregulated with slight increase in JNK and no change in p38MAPK after application of stretch. Inhibition had effects on proliferation (1.075±0.024, P<0.05 GF109203X); (1.418±0.021, P>0.05 SP600125) and (1.461±0.01, P>0.05 SB203580). These findings show that mechanical stretch can promote magnitude-dependent proliferative modulation through PKC and possibly JNK but not via p38MAPK in hBSMCs.
authors.affiliation: Department of Urology, West China Hospital, Sichuan University, Chengdu, Sichuan, PR China.
authors.forename: Romel
authors.initials: R
authors.lastname: Wazir
authors.forename: De-Yi
authors.initials: DY
authors.lastname: Luo
authors.forename: Yi
authors.initials: Y
authors.lastname: Dai
authors.forename: Xuan
authors.initials: X
authors.lastname: Yue
authors.forename: Ye
authors.initials: Y
authors.lastname: Tian
authors.forename: Kun-Jie
authors.initials: KJ
authors.lastname: Wang
mesh_terms: D049109:Cell Proliferation / Q000187:drug effects*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D052580:Muscle Stretching Exercises; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D001743:Urinary Bladder / Q000166:cytology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D011493:Protein Kinase C; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases
keywords: Bladder smooth muscle cell; JNK; PKC; Proliferation; Stretch; p38