Intersectin links WNK kinases to endocytosis of ROMK1.
With-no-lysine (WNK) kinases are a novel family of protein kinases characterized by an atypical placement of the catalytic lysine. Mutations of 2 family members, WNK1 and WNK4, cause pseudohypoaldosteronism type 2 (PHA2), an autosomal-dominant disease characterized by hypertension and hyperkalemia. WNK1 and WNK4 stimulate clathrin-dependent endocytosis of renal outer medullar potassium 1 (ROMK1), and PHA2-causing mutations of WNK4 increase the endocytosis. How WNKs stimulate endocytosis of ROMK1 and how mutations of WNK4 increase the endocytosis are unknown. Intersectin (ITSN) is a multimodular endocytic scaffold protein. Here we show that WNK1 and WNK4 interacted with ITSN and that the interactions were crucial for stimulation of endocytosis of ROMK1 by WNKs. The stimulation of endocytosis of ROMK1 by WNK1 and WNK4 required specific proline-rich motifs of WNKs, but did not require their kinase activity. WNK4 interacted with ROMK1 as well as with ITSN. Disease-causing WNK4 mutations enhanced interactions of WNK4 with ITSN and ROMK1, leading to increased endocytosis of ROMK1. These results provide a molecular mechanism for stimulation of endocytosis of ROMK1 by WNK kinases.
He
Guocheng
G
Department of Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-8856, USA.
Wang
Hao-Ran
HR
Huang
Shao-Kuei
SK
Huang
Chou-Long
CL
D033942:Adaptor Proteins, Vesicular Transport / Q000378:metabolism*; D002460:Cell Line; D002966:Clathrin / Q000378:metabolism; D004705:Endocytosis; D005786:Gene Expression Regulation; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007668:Kidney; D015778:Minor Histocompatibility Antigens; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics / Q000378:metabolism*; D011392:Proline; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000076204:WNK Lysine-Deficient Protein Kinase 1; D018909:src Homology Domains
D033942:Adaptor Proteins, Vesicular Transport; D002966:Clathrin; D047908:Intracellular Signaling Peptides and Proteins; C086989:KCNJ1 protein, human; D015778:Minor Histocompatibility Antigens; D024661:Potassium Channels, Inwardly Rectifying; C115919:intersectin 1; D011392:Proline; D017346:Protein Serine-Threonine Kinases; D000076204:WNK Lysine-Deficient Protein Kinase 1; C498743:WNK1 protein, human