A role for calcium-calmodulin in regulating nitric oxide production during skeletal muscle satellite cell activation

Abstract

RE.A role for calcium-calmodulin in regulating nitric oxide production during skeletal muscle satellite cell activation. Am J Physiol Cell Physiol 296: C922-C929, 2009. First published January 21, 2009 doi:10.1152/ajpcell.00471.2008.-When skeletal muscle is stretched or injured, myogenic satellite cells are activated to enter the cell cycle. This process depends on nitric oxide (NO) production by NO synthase (NOS), matrix metalloproteinase activation, release of hepatocyte growth factor (HGF) from the extracellular matrix, and presentation of HGF to the c-met receptor as demonstrated by a primary culture and in vivo assays. We now add evidence that calcium-calmodulin is involved in the satellite cell activation cascade in vitro. Conditioned medium from cultures that were treated with a calcium ionophore (A23187, ionomycin) for 2 h activated cultured satellite cells and contained active HGF, similar to the effect of mechanical stretch or NO donor treatments. The response was abolished by addition of calmodulin inhibitors (calmidazolium, W-13, W-12) or a NOS inhibitor N G -nitro-L-arginine methyl ester hydrochloride but not by its less inactive enantiomer N G -nitro-Darginine methyl ester hydrochloride. Satellite cells were also shown to express functional calmodulin protein having a calcium-binding activity at 12 h postplating, which is the time at which the calcium ionophore was added in this study and the stretch treatment was applied in our previous experiments. Therefore, results from these experiments provide an additional insight that calcium-calmodulin mediates HGF release from the matrix and that this step in the activation pathway is upstream from NO synthesis. muscle regeneration; stretch-activation SKELETAL MUSCLE SATELLITE cells are resident myogenic stem cells normally found in a quiescent state in adult skeletal muscles. When muscle is injured, overused, or mechanically stretched, these cells are activated to enter the cell cycle, divide, differentiate, and fuse with muscle fibers to repair damaged regions and to enhance hypertrophy of muscle fibers (reviewed in Refs. 7,10,17). Therefore, mechanical changes in muscle can initiate events that lead to satellite cell activation, although the mechanism has not been clearly delineated.Of all growth factors studied thus far, only hepatocyte growth factor (HGF) provides a signal that can activate quiescent satellite cells in primary culture and in vivo (1,20). HGF is a heparin-binding protein localized in the extracellular domain of uninjured skeletal muscle fibers, and its predominant form is the active heterodimer of the 60-kDa ␣-chain and 30-kDa ␤-chain (25). The intracellular signaling receptor for HGF is the c-met proto-oncogene, and its message and protein have been found in quiescent and activated satellite cells (1,8,20). Thus release of HGF from its sequestration and subsequent presentation to the c-met receptor may be a critical aspect of the activation of quiescent satellite cells.In previous works, we employed a FlexerCell system (Flexcell Int...

Redox Control of Skeletal Muscle Regeneration

“…In vitro, the stretching of myofibers induces hepatocyte growth factor (a potent MuSC mitogenic factor) release in a metalloprotease and NO -dependent manner (356). Upstream, calciumcalmodulin, known to associate with NOS in other cell types (347), activates NOS activity in MuSCs; its specific inhibition abrogates the calcium ionophore-induced MuSC activation (320). Collectively, these data argue for a positive role of NO in MuSC activation after muscle injury.…”

PGC-1α regulation by exercise training and its influences on muscle function and insulin sensitivity

“…Nitric oxide (NO) production is increased during contractile activity (13,149,185). Both endothelial and neuronal isoforms of NO synthase (eNOS and nNOS, respectively) have been shown to be activated by Ca 2ϩ /calmodulin and AMPK (34,35,47,161,197). Several studies suggest a role of endogenous NO in AMPKand Ca 2ϩ -dependent regulation of PGC-1␣, GLUT4, and mitochondrial genes (119,128).…”

Methylene Blue for Distributive Shock: A Potential New Use of an Old Antidote

“…All isoforms of NOS utilize L-arginine as a substrate along with oxygen and reduced nicotinamide-adenine-dinucleotide phosphate as co-substrates [18]. In addition, all isoforms of NOS bind calmodulin and calcium; activated calmodulin is important for the regulation of eNOS and nNOS activity [19]. Production of NO is a two-step process: In the first step, NOS hydroxylates L-arginine to an intermediate known as N-hydroxy-L-arginine.…”