The Expression And Functional Activities Of Myosin Ⅱ In Prostate

Background Benign prostatic hyperplasia(BPH)is the most common pathologic process interfering quality of life for aging males.BPH/LUTS is mainly caused by increased prostatic volume and changed smooth muscle(SM)tone,as well as decompensation and over-activity of bladder.Recent studies have shown that SM myosin Ⅱ(SMM Ⅱ)and non-muscle myosin II(NMM Ⅱ)may be associated with SM tone and cell proliferation and apoptosis,respectively.Objective To investigate the expression and functional activities of myosin II in prostate.Methods In this study,competitive RT-PCR,real-time RT-PCR,Western blot,Masson’s trichrome staining,immunofluroscence staining,Confocal,Organ bath and flow cytometry were conducted.The expression of SMM II isoforms(SM-A/-B,SM1/2 and LC17a/b)and NMM Ⅱ isoforms(NMMHC-A,B,C)was detected.And the contractile characteristics of prostate SM and prostatic cell proliferation and apoptosis were also investigated.Results Prostatic SM generated significant force induced by phenylephrine with an intermediate tonicity between phasic bladder and tonic aorta type contractility.Correlating with this kind of intermediate tonicity,rat prostate mainly expressed LC17a and SM1 but with relatively equal expression of SM-B at the mRNA level.Meanwhile,SM myosin heavy chain(SM MHC)present only in the stroma while NMMHC-A,B,C were present both in the stroma and endothelial.With Blebbistatin(BLEB)being intraprostatically injected in rat,SM MHC,NMMHC-A and NMMHC-B were found significantly attenuated through a mechanism involving MLC20 dephosphorylation,along with lessened phenylephrine-induced contraction and decreased prostatic weight.In addition,surgical castration upregulated the expression of SM MHC and enhanced prostatic SM contractility.T deprivation altered prostate SMM II isoform composition with upregulation of SM-B and SM2 but downregulation of LC17a,favoring a faster more phasic-type contraction.Meanwhile,NMMHC-A and NMMHC-C were found decreased and NMMHC-B was reletively increaed,along with decreased cell proliferation and increased apoptosis by castration.Conclusions The expression and functional activities of myosin II may regulate the dynamic and static components of prostate and may be mediated by testosterone.