Abstract
In skeletal muscles from patient suffering of Duchenne Muscular Dystrophy and from mdx mice, the absence of the cytoskeleton protein dystrophin has been shown to be essential for maintaining a normal calcium influx. We showed that a TRPC store-dependent cation influx is increased by loss of dystrophin or a scaffolding protein α1-syntrophin, however the mechanisms of this calcium mishandling are incompletely understood. First of all, we confirmed that TRPC1 but also STIM1 and Orai1 are supporting the store-operated cation entry which is enhanced in dystrophin-deficient myotubes. Next, we demonstrated that inhibition of PLC or PKC in dystrophin-deficient myotubes restores elevated cation entry to normal levels similarly to enforced minidystrophin expression. In addition, silencing α1-syntrophin also increased cation influx in a PLC/PKC dependent pathway. We also showed that α1-syntrophin and PLCβ are part of a same protein complex reinforcing the idea of their inter-relation in calcium influx regulation. This elevated cation entry was decreased to normal levels by chelating intracellular free calcium with BAPTA-AM. Double treatments with BAPTA-AM and PLC or PKC inhibitors suggested that the elevation of cation influx by PLC/PKC pathway is dependent on cytosolic calcium. All these results demonstrate an involvement in dystrophin-deficient myotubes of a specific calcium/PKC/PLC pathway in elevation of store-operated cation influx supported by the STIM1/Orai1/TRPC1 proteins, which is normally regulated by the α1-syntrophin/dystrophin scaffold.
Copyright © 2012 Elsevier Ltd. All rights reserved.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Calcium / metabolism*
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Calcium Channels / chemistry
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Calcium Channels / genetics
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Calcium Channels / metabolism
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Calcium Signaling / drug effects
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Calcium-Binding Proteins / antagonists & inhibitors
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Calcium-Binding Proteins / genetics
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Calcium-Binding Proteins / metabolism
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Cell Line
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Chelating Agents / pharmacology
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Dystrophin / genetics
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Dystrophin / metabolism*
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Egtazic Acid / analogs & derivatives
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Egtazic Acid / pharmacology
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Enzyme Inhibitors / pharmacology
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Membrane Glycoproteins / antagonists & inhibitors
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Membrane Glycoproteins / genetics
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Membrane Glycoproteins / metabolism
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Membrane Proteins / antagonists & inhibitors
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Membrane Proteins / genetics
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Membrane Proteins / metabolism
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Mice
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Muscle Fibers, Skeletal / metabolism*
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Muscle Proteins / antagonists & inhibitors
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Muscle Proteins / genetics
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Muscle Proteins / metabolism
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ORAI1 Protein
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Phospholipase C beta / antagonists & inhibitors
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Phospholipase C beta / metabolism*
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Protein Kinase C / antagonists & inhibitors
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Protein Kinase C / metabolism*
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RNA Interference
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RNA, Small Interfering / metabolism
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Signal Transduction
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Stromal Interaction Molecule 1
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TRPC Cation Channels / antagonists & inhibitors
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TRPC Cation Channels / genetics
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TRPC Cation Channels / metabolism
Substances
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Calcium Channels
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Calcium-Binding Proteins
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Chelating Agents
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Dystrophin
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Enzyme Inhibitors
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Membrane Glycoproteins
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Membrane Proteins
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Muscle Proteins
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ORAI1 Protein
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Orai1 protein, mouse
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RNA, Small Interfering
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Stim1 protein, mouse
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Stromal Interaction Molecule 1
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TRPC Cation Channels
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syntrophin alpha1
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transient receptor potential cation channel, subfamily C, member 1
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1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester
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Egtazic Acid
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Protein Kinase C
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Phospholipase C beta
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Calcium