Downregulation of TRPC6 expression is a critical molecular event during FK506 treatment for overactive bladder

Area of Science:

• Urology
• Pharmacology
• Cell Biology

Background:

• Overactive bladder (OAB) symptoms can be improved by FK506, but its mechanism remains unclear.
• Transient Receptor Potential Canonical 6 (TRPC6) channels are implicated in bladder smooth muscle function.
• Understanding the interaction between FK506 and TRPC6 is crucial for OAB therapeutic development.

Purpose of the Study:

• To investigate the effect of FK506 on TRPC6 in bladder smooth muscle.
• To explore the role of TRPC6 in the pathophysiology of OAB.
• To elucidate the mechanism by which FK506 exerts its therapeutic effects in OAB.

Main Methods:

• Urodynamic studies in a rat model of OAB induced by bladder outlet obstruction (BOO).
• Western blot, RT-PCR, and immunofluorescence staining to assess TRPC6 expression in rat and human bladder tissues.
• In vitro studies using cultured bladder smooth muscle cells (BSMCs) treated with PDGF, TRPC6 siRNAs, and FK506 to evaluate cell proliferation, Ca2+ influx, and contractility.
• Immunofluorescence and co-immunoprecipitation assays to examine NFAT translocation and TRPC6-FKBP12 interaction.

Main Results:

• FK506 administration improved urodynamic indices in OAB rats, correlating with reduced TRPC6 expression.
• TRPC6 was expressed in both rat and human bladder tissues, with elevated levels in OAB.
• FK506 and TRPC6 siRNAs attenuated PDGF-induced increases in BSMC proliferation, Ca2+ influx, and contractility.
• FK506 inhibited NFAT nuclear translocation and disrupted the interaction between TRPC6 and FKBP12.

Conclusions:

• FK506 demonstrates therapeutic potential for OAB by modulating TRPC6 activity in bladder smooth muscle.
• TRPC6 represents a promising molecular target for the development of novel OAB therapies.
• The findings provide mechanistic insights into FK506's action, involving TRPC6 and NFAT signaling pathways.