title: PKC-dependent coupling of calcium permeation through transient receptor potential canonical 3 (TRPC3) to calcineurin signaling in HL-1 myocytes.
abstract: Cardiac transient receptor potential canonical (TRPC) channels are crucial upstream components of Ca(2+)/calcineurin/nuclear factor of activated T cells (NFAT) signaling, thereby controlling cardiac transcriptional programs. The linkage between TRPC-mediated Ca(2+) signals and NFAT activity is still incompletely understood. TRPC conductances may govern calcineurin activity and NFAT translocation by supplying Ca(2+) either directly through the TRPC pore into a regulatory microdomain or indirectly via promotion of voltage-dependent Ca(2+) entry. Here, we show that a point mutation in the TRPC3 selectivity filter (E630Q), which disrupts Ca(2+) permeability but preserves monovalent permeation, abrogates agonist-induced NFAT signaling in HEK293 cells as well as in murine HL-1 atrial myocytes. The E630Q mutation fully retains the ability to convert phospholipase C-linked stimuli into L-type (Ca(V)1.2) channel-mediated Ca(2+) entry in HL-1 cells, thereby generating a dihydropyridine-sensitive Ca(2+) signal that is isolated from the NFAT pathway. Prevention of PKC-dependent modulation of TRPC3 by either inhibition of cellular kinase activity or mutation of a critical phosphorylation site in TRPC3 (T573A), which disrupts targeting of calcineurin into the channel complex, converts cardiac TRPC3-mediated Ca(2+) signaling into a transcriptionally silent mode. Thus, we demonstrate a dichotomy of TRPC-mediated Ca(2+) signaling in the heart constituting two distinct pathways that are differentially linked to gene transcription. Coupling of TRPC3 activity to NFAT translocation requires microdomain Ca(2+) signaling by PKC-modified TRPC3 complexes. Our results identify TRPC3 as a pivotal signaling gateway in Ca(2+)-dependent control of cardiac gene expression.
authors.affiliation: Institute of Pharmaceutical Sciences, University of Graz, 8010 Graz, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Poteser
authors.forename: Hannes
authors.initials: H
authors.lastname: Schleifer
authors.forename: Michaela
authors.initials: M
authors.lastname: Lichtenegger
authors.forename: Michaela
authors.initials: M
authors.lastname: Schernthaner
authors.forename: Thomas
authors.initials: T
authors.lastname: Stockner
authors.forename: C Oliver
authors.initials: CO
authors.lastname: Kappe
authors.forename: Toma N
authors.initials: TN
authors.lastname: Glasnov
authors.forename: Christoph
authors.initials: C
authors.lastname: Romanin
authors.forename: Klaus
authors.initials: K
authors.lastname: Groschner
mesh_terms: D000818:Animals; D019703:Calcineurin / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D006801:Humans; D017136:Ion Transport; D051379:Mice; D009206:Myocardium / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D050778:NFATC Transcription Factors / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D015398:Signal Transduction; D050052:TRPC Cation Channels / Q000378:metabolism*
chemical_list: D050778:NFATC Transcription Factors; D050052:TRPC Cation Channels; C104603:TRPC3 cation channel; D011493:Protein Kinase C; D019703:Calcineurin; D002118:Calcium