J Biol Chem 2025 Sep 24;:110766. doi: 10.1016/j.jbc.2025.110766.

Differential modulation of polycystin-2 gain-of-function channels by cysteine-reactive compounds, amphiphilic substances and S4-S5 linker mutations.

???displayArticle.abstract???
Polycystin-2 (PC2) mutations are responsible for ∼15% of cases of autosomal-dominant polycystic kidney disease (ADPKD). PC2 belongs to the transient receptor potential (TRP) ion channel family and can function as a homotetrameric nonselective cation channel. Little is known about its gating mechanism, and no specific PC2 activators or inhibitors have been identified. In this study, we performed a comparative electrophysiological analysis of two well-established gain-of-function (GOF) PC2 constructs, PC2 F604P and PC2 L677A N681A, expressed in Xenopus laevis oocytes. Interestingly, PC2 F604P, but not PC2 L677A N681A, could be inhibited by several membrane-permeable cysteine-reactive compounds. In contrast, positively charged cysteine-reactive compounds had no inhibitory effect. Thus, the inhibitory effect probably involves covalent modification of intracellular cysteine residues. Consistent with this, site-directed mutagenesis revealed a critical functional role of the free cysteine residue C593, localized in the intracellular S4-S5 linker of PC2 F604P. Moreover, the ion channel function of PC2 F604P was disturbed by S4-S5 linker mutations flanking C593. Interestingly, several structurally unrelated amphiphilic substances mimicked the inhibitory effect of membrane-permeable cysteine-reactive compounds on PC2 F604P without affecting PC2 L677A N681A. Collectively, our data suggest a critical role of the S4-S5 linker and the plasma membrane lipid environment in F604P-triggered PC2 gating. Finally, we demonstrated that the ADPKD-associated mutation located within the S4-S5 linker (N580K) completely abolished or significantly reduced currents mediated by PC2 F604P or PC2 L677A N681A, respectively. These findings provide new insights into molecular mechanisms involved in PC2 gating.

???displayArticle.pubmedLink??? 41005473
???displayArticle.link??? J Biol Chem