Effect And Mechanism Of CD38-FKBP12.6 Pathway On Detrusor Function In Mice

Background and Objective: CD38(Cluster of Differentiation 38)-FKBP12.6(FK506 Binding Protein 12.6)pathway is involved in the biological process and disease occurrence of various tissues and organs by affecting intracellular calcium signal,but we know little about its specific role in detrusor.The aim of this research is to study the effect and mechanism of CD38-FKBP12.6 pathway on the detrusor of normal mice and DO(Detrusor Overactivity)mice.Methods: DO models of mice were established by PBOO(Partial Bladder Outlet Obstruction).Western blot assay was used to detect the expression of CD38,FKBP12.6,IP3R(Inositol-1,4,5-trisphosphate Receptor),TRPM4(Transient Receptor Potential Melastatin-4),mTOR(mammalian Target of Rapamycin),p-mTOR(p-mammalian Target of Rapamycin)and RyR(Ryanodine Receptor)in bladder smooth muscle.The expression of CD38 and FKBP12.6 in DO detrusor and the co-localization of FKBP12.6 and IP3 R in mouse detrusor were studied by immunofluorescence staining.The micturition frequency of CD38 and FKBP12.6 knockout mice and the effect of FKBP12.6 knockout on the micturition frequency of DO mice were researched by void spots test.The influences of CD38 and FKBP12.6 knockout on the bladder function and the impact of FKBP12.6 knockout on the DO mice bladder function were analyzed by the urodynamic test.The detrusor strips test was applied to research the contractions of detrusor in FKBP12.6 knockout mice and DO mice.The effects of FKBP12.6 knockout on the bladder sensitivity of normal mice and DO mice were measured by VMR(Visceromotor Response).Immunoprecipitation was implemented to research the interaction between IP3 R and FKBP12.6 in mice detrusor.The mechanism of bladder function changes after FKBP12.6 knockout was researched by the drug inhibition test.Results: 1.CD38 affected the bladder function of mice:(1)The expression of CD38 in the detrusor of DO mice was significantly increased(P < 0.05).(2)Compared with wild-type mice(CD38 +/+,WT),CD38 heterozygous mice(CD38 +/-,HZ)showed a 50% decrease in CD38 expression in bladder detrusor(P < 0.05).(3)The down-regulation of CD38 expression did not affect the general morphology of the bladder.(4)The down-regulation of CD38 increased the frequency of micturition(P < 0.01).(5)The down-regulation of CD38 resulted in the instability of the bladder(P < 0.01).2.FKBP12.6 affected the bladder function of mice:(1)FKBP12.6 was significantly down-regulated in detrusor of DO mice(P < 0.01).(2)FKBP12.6 knockout did not affect the morphology of the bladder and detrusor in mice.(3)FKBP12.6 knockout increased the frequency of micturition in mice(P < 0.01).(4)FKBP12.6 knockout increased bladder sensitivity(P < 0.01),and the contraction frequency of detrusor strips(P < 0.05)which could be inhibited by 2-ABP(2-aminoethyldiphenyl borate).(5)IP3R inhibitor 2-APB and TRPM4 inhibitor 9-PHE(9-phenanthrol)significantly reduced the frequency of micturition(P < 0.05)and detrusor instability(P < 0.05)in KO mice.(6)FKBP12.6 gene knockout did not affect the expression of IP3 R and TRPM4 in detrusor,but FKBP12.6 could directly affect IP3 R in mice detrusor.(7)Knockout of FKBP12.6 could activate mTOR in detrusor(P < 0.05).(8)After FKBP12.6 knockout,the cation transport of detrusor muscle was significantly affected.3.FKBP12.6 affected the bladder function of DO mice:(1)FKBP12.6 knockout did not have a significant effect on the morphology of DO detrusor in mice.(2)FKBP12.6 knockout increased the micturition frequency of DO mice(P < 0.05)and increased the fluctuation of bladder pressure during the storage period(P < 0.05).(3)FKBP12.6 knockout increased the sensitivity of DO bladder(P < 0.05).(4)FKBP12.6 knockout enhanced the contraction of DO detrusor(P < 0.01).(5)FKBP12.6 knockout resulted in a significant down-regulation of RyR expression in DO detrusor(P < 0.01).Conclusion: 1.The stable expression of CD38 plays an important role in the maintenance of bladder function in mice.The down-regulation of CD38 will lead to bladder instability in mice.2.FKBP12.6 plays an important role in maintaining the normal bladder function of mice.FKBP12.6 knockout can cause bladder dysfunction in mice,which may be related to the abnormal activation of IP3R/TRPM4 pathway.3.FKBP12.6 knockout will lead to the down-regulation of RyR expression in DO detrusor of mice,which will aggravate the bladder dysfunction of DO.