title: PKD2 functions as an epidermal growth factor-activated plasma membrane channel.
abstract: PKD2, or polycystin 2, the product of the gene mutated in type 2 autosomal dominant polycystic kidney disease, belongs to the transient receptor potential channel superfamily and has been shown to function as a nonselective cation channel in the plasma membrane. However, the mechanism of PKD2 activation remains elusive. We show that PKD2 overexpression increases epidermal growth factor (EGF)-induced inward currents in LLC-PK(1) kidney epithelial cells, while the knockdown of endogenous PKD2 by RNA interference or the expression of a pathogenic missense variant, PKD2-D511V, blunts the EGF-induced response. Pharmacological experiments indicate that the EGF-induced activation of PKD2 occurs independently of store depletion but requires the activity of phospholipase C (PLC) and phosphoinositide 3-kinase (PI3K). Pipette infusion of purified phosphatidylinositol-4,5-bisphosphate (PIP(2)) suppresses the PKD2-mediated effect on EGF-induced conductance, while pipette infusion of phosphatidylinositol-3,4,5-trisphosphate (PIP(3)) does not have any effect on this conductance. Overexpression of type Ialpha phosphatidylinositol-4-phosphate 5-kinase [PIP(5)Kalpha], which catalyzes the formation of PIP(2), suppresses EGF-induced currents. Biochemical experiments show that PKD2 physically interacts with PLC-gamma2 and EGF receptor (EGFR) in transfected HEK293T cells and colocalizes with EGFR and PIP(2) in the primary cilium of LLC-PK(1) cells. We propose that plasma membrane PKD2 is under negative regulation by PIP(2). EGF may reduce the threshold of PKD2 activation by mechanical and other stimuli by releasing it from PIP(2)-mediated inhibition.
authors.affiliation: Department of Cell Biology, University of Oklahoma Health Sciences Center, 941 Stanton L. Young Boulevard, Oklahoma City, OK 73104, USA.
authors.forename: Rong
authors.initials: R
authors.lastname: Ma
authors.forename: Wei-Ping
authors.initials: WP
authors.lastname: Li
authors.forename: Dana
authors.initials: D
authors.lastname: Rundle
authors.forename: Jin
authors.initials: J
authors.lastname: Kong
authors.forename: Hamid I
authors.initials: HI
authors.lastname: Akbarali
authors.forename: Leonidas
authors.initials: L
authors.lastname: Tsiokas
mesh_terms: D000483:Alleles; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002923:Cilia / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D066246:ErbB Receptors / Q000032:analysis / Q000378:metabolism; D006801:Humans; D007473:Ion Channels / Q000235:genetics / Q000378:metabolism*; D007668:Kidney / Q000166:cytology; D018374:LLC-PK1 Cells; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D020125:Mutation, Missense; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology; D051966:Phospholipase C gamma; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D034622:RNA Interference; D013552:Swine; D050396:TRPP Cation Channels; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D002118:Calcium; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D007473:Ion Channels; D008565:Membrane Proteins; D019869:Phosphatidylinositol 3-Kinases; D019269:Phosphatidylinositol 4,5-Diphosphate; D051966:Phospholipase C gamma; D017853:Phosphotransferases (Alcohol Group Acceptor); D050396:TRPP Cation Channels; D010738:Type C Phospholipases; C020077:1-phosphatidylinositol-4-phosphate 5-kinase