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Molecular determinants of PKA-dependent inhibition of TRPC5 channel

Title
Molecular determinants of PKA-dependent inhibition of TRPC5 channel
Author
김선정
Keywords
canonical transient receptor potential isoform 5; nonselective cation channels; protein kinase A
Issue Date
2011-10
Publisher
AMER PHYSIOLOGICAL SOC, 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA
Citation
AMERICAN JOURNAL OF PHYSIOLOGY-CELL PHYSIOLOGY , 301, 4, C823-C832
Abstract
Canonical transient receptor potential (TRPC) channels are Ca(2+)-permeable, nonselective cation channels that are widely expressed in numerous cell types. Here, we demonstrate a new mechanism of TPRC isofom 5 (TRPC5) regulation, via cAMP signaling via G alpha(s). Monovalent cation currents in human embryonic kidney-293 cells transfected with TRPC5 were induced by G protein activation with intracellular perfusion of GTP gamma S or by muscarinic stimulation. This current could be inhibited by a membrane-permeable analog of cAMP, 8-bromo-cAMP, by isoproterenol, by a constitutively active form of G alpha(s) [G alpha(s) (Q227L)], and by forskolin. These inhibitory effects were blocked by the protein kinase A (PKA) inhibitors, KT-5720 and H-89, as well as by two point mutations at consensus PKA phosphorylation sites on TRPC5 (S794A and S796A). Surface expression of several mutated versions of TRPC5, quantified using surface biotinylation, were not affected by G alpha(s) (Q227L), suggesting that trafficking of this channel does not underlie the regulation we report. This mechanism of inhibition was also found to be important for the closely related channel, TRPC4, in particular for TRPC4 alpha, although TRPC4 beta was also affected. However, this form of regulation was not found to be involved in TRPC6 and transient receptor potential vanilloid 6 function. In murine intestinal smooth muscle cells, muscarinic stimulation-induced cation currents were mediated by TRPC4 (>80%) and TRPC6. In murine intestinal smooth muscle cells, 8-bromo-cAMP, adrenaline, and isoproterenol decreased nonselective cation currents activated by muscarinic stimulation or GTP gamma S. Together, these results suggest that TRPC5 is directly phosphorylated by G(s)/cAMP/PKA at positions S794 and S796. This mechanism may be physiologically important in visceral tissues, where muscarinic receptor and beta(2)-adrenergic receptor are involved in the relaxation and contraction of smooth muscles.
URI
http://www.physiology.org/doi/abs/10.1152/ajpcell.00351.2010
ISSN
0363-6143
DOI
10.1152/ajpcell.00351.2010
Appears in Collections:
COLLEGE OF ENGINEERING[S](공과대학) > ELECTRICAL AND BIOMEDICAL ENGINEERING(전기·생체공학부) > Articles
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