title: Phospholipase C epsilon (PLCε) induced TRPC6 activation: a common but redundant mechanism in primary podocytes.
abstract: In eukaryotic cells, activation of phospholipase C (PLC)-coupled membrane receptors by hormones leads to an increase in the intracellular Ca(2+) concentration [Ca(2+) ]i . Catalytic activity of PLCs results in the hydrolysis of phosphatidylinositol 4,5-bisphosphate to generate inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG) which opens DAG-sensitive classical transient receptor channels 3, 6, and 7 (TRPC3/6/7), initiating Ca(2+) influx from the extracellular space. Patients with focal segmental glomerulosclerosis (FSGS) express gain-of-function mutants of TRPC6, while others carry loss-of-function mutants of PLCε, raising the intriguing possibility that both proteins interact and might work in the same signalling pathway. While TRPC6 activation by PLCβ and PLCγ isozymes was extensively studied, the role of PLCε in TRPC6 activation remains elusive. TRPC6 was co-immunoprecipitated with PLCε in a heterologous overexpression system in HEK293 cells as well as in freshly isolated murine podocytes. Receptor-operated TRPC6 currents in HEK293 cells expressing TRPC6 were reduced by a specific PLCε siRNA and by a PLCε loss-of-function mutant isolated from a patient with FSGS. PLCε-induced TRPC6 activation was also identified in murine embryonic fibroblasts (MEFs) lacking Gαq/11 proteins. Further analysis of the signal transduction pathway revealed a Gα12/13 Rho-GEF activation which induced Rho-mediated PLCε stimulation. Therefore, we identified a new pathway for TRPC6 activation by PLCε. PLCε-/- podocytes however, were undistinguishable from WT podocytes in their angiotensin II-induced formation of actin stress fibers and their GTPγS-induced TRPC6 activation, pointing to a redundant role of PLCε-mediated TRPC6 activation at least in podocytes.
authors.affiliation: Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Hermann
authors.initials: H
authors.lastname: Kalwa
authors.forename: Ursula
authors.initials: U
authors.lastname: Storch
authors.forename: Jana
authors.initials: J
authors.lastname: Demleitner
authors.forename: Susanne
authors.initials: S
authors.lastname: Fiedler
authors.forename: Tim
authors.initials: T
authors.lastname: Mayer
authors.forename: Martina
authors.initials: M
authors.lastname: Kannler
authors.forename: Meike
authors.initials: M
authors.lastname: Fahlbusch
authors.forename: Holger
authors.initials: H
authors.lastname: Barth
authors.forename: Alan
authors.initials: A
authors.lastname: Smrcka
authors.forename: Friedhelm
authors.initials: F
authors.lastname: Hildebrandt
authors.forename: Thomas
authors.initials: T
authors.lastname: Gudermann
authors.forename: Alexander
authors.initials: A
authors.lastname: Dietrich
mesh_terms: D000818:Animals; D020013:Calcium Signaling / Q000502:physiology; D057809:HEK293 Cells; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D054801:Phosphoinositide Phospholipase C / Q000378:metabolism*; D050199:Podocytes / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D050052:TRPC Cation Channels / Q000378:metabolism*; D000074287:TRPC6 Cation Channel
chemical_list: D050052:TRPC Cation Channels; D000074287:TRPC6 Cation Channel; C117032:TRPC6 protein, human; C492146:Trpc6 protein, mouse; D015544:Inositol 1,4,5-Trisphosphate; D054801:Phosphoinositide Phospholipase C; C423320:phospholipase C epsilon