Forty‐five Vasopressin‐Regulated Phosphoproteins Involved in Control of Collecting Duct Water Transport

Abstract

Vasopressin regulates renal water excretion through actions to regulate aquaporin 2 trafficking and transcription. These actions are dependent on vasopressin‐induced phosphorylation changes in collecting duct cells. Although some phosphorylation targets are well known including aquaporin 2 itself, the full gamut of vasopressin‐induced phosphorylation changes is unexplored. Our prior studies using quantitative phosphoproteomics have identified phosphorylation changes in cultured mouse mpkCCD cells (PMID: 33346914) and native inner medullary collecting duct cells (PMID: 31313956). Here, we have curated a list of vasopressin‐regulated phosphoproteins based on a consensus of the two studies. This includes 51 phosphorylation sites in 45 proteins, archived at https://esbl.nhlbi.nih.gov/Databases/AVP‐Phos/. Among these sites are 23 consensus protein kinase A (PKA) sites that are increased in response to vasopressin, consistent with a central role for PKA in vasopressin signaling. Fifteen downregulated phosphorylation sites are associated with decreased activation of the MAP kinases, ERK1 and ERK2. The remaining 13 sites are likely to be phosphorylated by other kinases. Regulated phosphoproteins include several protein kinases, namely Mink1, Camkk2, Cdk18, Prkar2a, Erbb3, and Src, which play likely roles downstream from PKA. Gene Ontology term analysis reveals multiple vasopressin‐regulated phosphoproteins involved in known vasopressin‐regulated processes: “transmembrane transport” (Aqp2, Itpr1, Itpr2, Itpr3), “actin cytoskeleton organization” (Bin1, Myo9b, Pdlim5, Slc9a3r1, Specc1l), “regulation of GTPase activity” (Als2, Arfgef1, Ralgapa2), “exocytosis” (Exoc7, Stxbp5, Itsn1), “endocytosis” (Bin1, Itsn1), “cell cycle” (Sept9, Arhgef2, Specc1l, Src), “regulation of transcription” (Hdac4, Ctnnb1, Lrrfip1, Tsc22d4), “Wnt signaling pathway” (Ctnnb1, Slc9a3r1, Src). Overall, this study provides a list of vasopressin‐regulated phosphoproteins likely to be involved in vasopressin‐mediated regulation of collecting duct water transport, providing grist for future studies.