Protein phosphatase-1α interacts with and dephosphorylates polycystin-1

• Published in: PloS one 2012-06, Vol.7 (6), p.e36798-e36798
• Main Authors: Parnell, Stephen C, Puri, Sanjeev, Wallace, Darren P, Calvet, James P
• Format: Article
• Language: English
• Subjects: Amino Acid Motifs; Amino Acid Sequence; Amino acids; Amino Acids - metabolism; Animals; Binding; Biochemistry; Biology; Calcineurin; Cell cycle; Conserved sequence; Cysts; Dephosphorylation; Enzymes; Fusion protein; Genes; HEK293 Cells; Holoenzymes - metabolism; Humans; Immunoprecipitation; Kidney diseases; Kinases; Localization; Mice; Models, Biological; Molecular biology; Molecular Sequence Data; Mutation; Mutation - genetics; Phosphatase; Phosphorylation; Plasmids; Polycystic kidney; Polycystic kidney disease 1 protein; Protein Binding; Protein kinase A; Protein phosphatase; Protein Phosphatase 1 - metabolism; Proteins; Recombinant Fusion Proteins - metabolism; Regulation; Regulatory sequences; Sequence Alignment; Signaling; Substrate Specificity; TRPP Cation Channels - chemistry; TRPP Cation Channels - metabolism
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0036798

Polycystin signaling is likely to be regulated by phosphorylation. While a number of potential protein kinases and their target phosphorylation sites on polycystin-1 have been identified, the corresponding phosphatases have not been extensively studied. We have now determined that polycystin-1 is a regulatory subunit for protein phosphatase-1α (PP1α). Sequence analysis has revealed the presence of a highly conserved PP1-interaction motif in the cytosolic, C-terminal tail of polycystin-1; and we have shown that transfected PP1α specifically co-immunoprecipitates with a polycystin-1 C-tail construct. To determine whether PP1α dephosphorylates polycystin-1, a PKA-phosphorylated GST-polycystin-1 fusion protein was shown to be dephosphorylated by PP1α but not by PP2B (calcineurin). Mutations within the PP1-binding motif of polycystin-1, including an autosomal dominant polycystic kidney disease (ADPKD)-associated mutation, significantly reduced PP1α-mediated dephosphorylation of polycystin-1. The results suggest that polycystin-1 forms a holoenzyme complex with PP1α via a conserved PP1-binding motif within the polycystin-1 C-tail, and that PKA-phosphorylated polycystin-1 serves as a substrate for the holoenzyme.