Open AccessPKD2 Functions as an Epidermal Growth Factor-Activated Plasma Membrane Channel
Author(s) -
Rong Ma,
Wei Ping Li,
Dana R. Rundle,
Jin Kong,
Hamid I. Akbarali,
Leonidas Tsiokas
Publication year - 2005
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.25.18.8285-8298.2005
Subject(s) - phospholipase c , epidermal growth factor , biology , phosphatidylinositol , microbiology and biotechnology , hek 293 cells , transfection , gene knockdown , epidermal growth factor receptor , phospholipase d , kinase , signal transduction , receptor , biochemistry , gene , apoptosis
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-PK1 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 (PIP2 ) suppresses the PKD2-mediated effect on EGF-induced conductance, while pipette infusion of phosphatidylinositol-3,4,5-trisphosphate (PIP3 ) does not have any effect on this conductance. Overexpression of type Iα phosphatidylinositol-4-phosphate 5-kinase [PIP(5)Kα], which catalyzes the formation of PIP2 , suppresses EGF-induced currents. Biochemical experiments show that PKD2 physically interacts with PLC-γ2 and EGF receptor (EGFR) in transfected HEK293T cells and colocalizes with EGFR and PIP2 in the primary cilium of LLC-PK1 cells. We propose that plasma membrane PKD2 is under negative regulation by PIP2 . EGF may reduce the threshold of PKD2 activation by mechanical and other stimuli by releasing it from PIP2 -mediated inhibition.