Objective To explore the roles of the mechanoreceptor Yes-associated protein 1(YAP1)and piezo type mechanosensitive ion channel component 2(PIEZO2)in mechanotransduction in mouse bladder urothelial cells.Methods Mouse bladder urothelial cells were subjected to mechanical stretching using the FX-6000T cell stretching system and treated with the YAP1-specific inhibitor verteporfin(VP).The expressions of PIEZO2,YAP1 and connective tissue growth factor(CTGF)at the mRNA and protein levels,as well as changes in cellular adenosine triphosphatase(ATP)concentration,were detected using reverse transcription quantitative PCR(RT-qPCR)and Western blotting(WB).Results After stretching stimulation,under the fluorescence microscope,it was observed that the diameter length of the stretched cells were longer than that before stretching,and the difference was statistically significant(P＜0.05).The expressions of YAP1,PIEZO2 and CTGF at the mRNA and protein levels were increased in the stretched group compared to those of the non-stretched group(P＜0.05).VP effectively reduced the expressions of YAP1,PIEZO2 and CTGF at the mRNA and protein levels after stretching stimulation(P＜0.05).Stretching stimulation significantly increased the intracellular ATP concentration,while VP was able to inhibit the increase in ATP concentration,with a statistically significant difference(P＜0.000 1).Conclusion Stretching stimulation increased the expressions of YAP1 and PIEZO2 in bladder urothelial cells and promoted the release of ATP;verteporfin inhibited the increase in YAP1 activity and the overexpression of PIEZO2 caused by stretching,thereby reducing the release of ATP.It is suggested that mouse bladder urothelial cells may primarily sense mechanical signals through the YAP1-PIEZO2-ATP pathway.

Objective:To investigate the role of mechanosensor Yes-associated protein 1 (YAP1) in urothelial cells in inducing bladder dysfunction in a partial bladder outlet obstruction (pBOO) model.Methods:Ten female C57BL/6 mice were included in this study and randomly divided into pBOO and sham groups based on body weight using a stratified pairing method, with 5 mice in each group. The pBOO group underwent proximal urethral ligation surgery, while the sham group underwent a sham operation. Two weeks after surgery, the urinary pattern was analyzed using the urine spot test. The significant increase in urine spot numbers indicated the successful establishment of the pBOO model. The mice were then sacrificed, and bladder tissues were weighed and stained with hematoxylin and eosin (HE) to observe morphological changes. The bladder urothelial layer was further isolated, and total cell proteins were extracted to detect the expression levels of YAP1 protein using Western blotting. Mouse immortalized bladder urothelial cells were divided into three experimental groups: the negative control (NC) group, which was treated with YAP1-NC lentivirus; the overexpression (OE) group, which was treated with YAP1-OE lentivirus to induce YAP1 protein overexpression; and the verteporfin treatment (VP) group, which was treated with verteporfin on the basis of the OE group. Real-time quantitative PCR and Western blotting were used to verify the transcription and expression levels of YAP1 protein, the co-transcriptional activator TEAD4 protein, and the phosphorylated protein DRP1-616 (at serine 616) of dynamin-related protein 1 (DRP1). An ATP detection kit was used to measure the ATP release concentration in the NC, OE, and VP groups. The interaction between YAP1 and TEAD4 was investigated using co-immunoprecipitation, and the expression of the mitochondrial marker translocase of the outer mitochondrial membrane 20 (Tom20) was observed using immunofluorescence staining.Results:The results of the urine spot test showed that the number of urine spots on the filter paper in the pBOO group was higher than that in the sham group within 6 hours [(283.0±9.1) spots vs. (3.7±0.3) spots, P<0.01], and the urine spots were scattered. The bladder wet weight in the pBOO group was significantly higher than that in the sham group [(105.70±6.84) mg vs. (22.33±1.20) mg, P<0.01]. Histological observations revealed reduced bladder mucosal folds and increased detrusor muscle thickness in the pBOO group. The expression of YAP1 protein in the bladder urothelial cells of the pBOO group was significantly upregulated compared to the sham group [(1.26±0.08) vs. (0.50±0.04), P<0.01]. In vitro experiments showed that compared to the NC group, the OE group had significantly increased expression of DRP1-616 [(0.94±0.05) vs. (0.33±0.01), P<0.01] and higher ATP release concentration [(24.45±0.16) μmol/mg vs. (19.67±0.42) μmol/mg, P<0.01]. In contrast, the VP group had significantly decreased expression of DRP1-616 [(0.29±0.04) vs. (0.94±0.05), P<0.01] and lower ATP release concentration [(10.55±0.01) μmol/mg vs. (24.45±0.16) μmol/mg, P<0.01] compared to the OE group. Co-immunoprecipitation experiments using YAP1 and TEAD4 antibodies showed that YAP1 and TEAD4 proteins could interact and form a transcriptional complex to regulate ATP release. Immunofluorescence staining revealed increased expression of Tom20 in the OE group compared to the NC group [(104.20±3.28) vs. (74.51±3.87), P<0.01]. Conclusions:In the pBOO-induced bladder dysfunction model, YAP1 is highly expressed in urothelial cells. YAP1 forms a transcriptional complex with TEAD4 to regulate ATP release by promoting mitochondrial fission via DRP1-616 expression, which is a key mechanism underlying pBOO-induced bladder dysfunction.

Objective To explore the roles of the mechanoreceptor Yes-associated protein 1(YAP1)and piezo type mechanosensitive ion channel component 2(PIEZO2)in mechanotransduction in mouse bladder urothelial cells.Methods Mouse bladder urothelial cells were subjected to mechanical stretching using the FX-6000T cell stretching system and treated with the YAP1-specific inhibitor verteporfin(VP).The expressions of PIEZO2,YAP1 and connective tissue growth factor(CTGF)at the mRNA and protein levels,as well as changes in cellular adenosine triphosphatase(ATP)concentration,were detected using reverse transcription quantitative PCR(RT-qPCR)and Western blotting(WB).Results After stretching stimulation,under the fluorescence microscope,it was observed that the diameter length of the stretched cells were longer than that before stretching,and the difference was statistically significant(P＜0.05).The expressions of YAP1,PIEZO2 and CTGF at the mRNA and protein levels were increased in the stretched group compared to those of the non-stretched group(P＜0.05).VP effectively reduced the expressions of YAP1,PIEZO2 and CTGF at the mRNA and protein levels after stretching stimulation(P＜0.05).Stretching stimulation significantly increased the intracellular ATP concentration,while VP was able to inhibit the increase in ATP concentration,with a statistically significant difference(P＜0.000 1).Conclusion Stretching stimulation increased the expressions of YAP1 and PIEZO2 in bladder urothelial cells and promoted the release of ATP;verteporfin inhibited the increase in YAP1 activity and the overexpression of PIEZO2 caused by stretching,thereby reducing the release of ATP.It is suggested that mouse bladder urothelial cells may primarily sense mechanical signals through the YAP1-PIEZO2-ATP pathway.

Objective:To investigate the role of mechanosensor Yes-associated protein 1 (YAP1) in urothelial cells in inducing bladder dysfunction in a partial bladder outlet obstruction (pBOO) model.Methods:Ten female C57BL/6 mice were included in this study and randomly divided into pBOO and sham groups based on body weight using a stratified pairing method, with 5 mice in each group. The pBOO group underwent proximal urethral ligation surgery, while the sham group underwent a sham operation. Two weeks after surgery, the urinary pattern was analyzed using the urine spot test. The significant increase in urine spot numbers indicated the successful establishment of the pBOO model. The mice were then sacrificed, and bladder tissues were weighed and stained with hematoxylin and eosin (HE) to observe morphological changes. The bladder urothelial layer was further isolated, and total cell proteins were extracted to detect the expression levels of YAP1 protein using Western blotting. Mouse immortalized bladder urothelial cells were divided into three experimental groups: the negative control (NC) group, which was treated with YAP1-NC lentivirus; the overexpression (OE) group, which was treated with YAP1-OE lentivirus to induce YAP1 protein overexpression; and the verteporfin treatment (VP) group, which was treated with verteporfin on the basis of the OE group. Real-time quantitative PCR and Western blotting were used to verify the transcription and expression levels of YAP1 protein, the co-transcriptional activator TEAD4 protein, and the phosphorylated protein DRP1-616 (at serine 616) of dynamin-related protein 1 (DRP1). An ATP detection kit was used to measure the ATP release concentration in the NC, OE, and VP groups. The interaction between YAP1 and TEAD4 was investigated using co-immunoprecipitation, and the expression of the mitochondrial marker translocase of the outer mitochondrial membrane 20 (Tom20) was observed using immunofluorescence staining.Results:The results of the urine spot test showed that the number of urine spots on the filter paper in the pBOO group was higher than that in the sham group within 6 hours [(283.0±9.1) spots vs. (3.7±0.3) spots, P<0.01], and the urine spots were scattered. The bladder wet weight in the pBOO group was significantly higher than that in the sham group [(105.70±6.84) mg vs. (22.33±1.20) mg, P<0.01]. Histological observations revealed reduced bladder mucosal folds and increased detrusor muscle thickness in the pBOO group. The expression of YAP1 protein in the bladder urothelial cells of the pBOO group was significantly upregulated compared to the sham group [(1.26±0.08) vs. (0.50±0.04), P<0.01]. In vitro experiments showed that compared to the NC group, the OE group had significantly increased expression of DRP1-616 [(0.94±0.05) vs. (0.33±0.01), P<0.01] and higher ATP release concentration [(24.45±0.16) μmol/mg vs. (19.67±0.42) μmol/mg, P<0.01]. In contrast, the VP group had significantly decreased expression of DRP1-616 [(0.29±0.04) vs. (0.94±0.05), P<0.01] and lower ATP release concentration [(10.55±0.01) μmol/mg vs. (24.45±0.16) μmol/mg, P<0.01] compared to the OE group. Co-immunoprecipitation experiments using YAP1 and TEAD4 antibodies showed that YAP1 and TEAD4 proteins could interact and form a transcriptional complex to regulate ATP release. Immunofluorescence staining revealed increased expression of Tom20 in the OE group compared to the NC group [(104.20±3.28) vs. (74.51±3.87), P<0.01]. Conclusions:In the pBOO-induced bladder dysfunction model, YAP1 is highly expressed in urothelial cells. YAP1 forms a transcriptional complex with TEAD4 to regulate ATP release by promoting mitochondrial fission via DRP1-616 expression, which is a key mechanism underlying pBOO-induced bladder dysfunction.