Cytoskeleton/stretch‐activated ion channel interaction regulates myogenic differentiation of skeletal myoblasts

Abstract

In the present study, we investigated the functional interaction between stress fibers (SFs) and stretch-activated channels (SACs) and its possible role in the regulation of myoblast differentiation induced by switch to differentiation culture in the presence or absence of sphingosine 1-phosphate. It was found that there was a clear temporal correlation between SF formation and SAC activation in differentiating C2C12 myoblasts. Inhibition of actin polymerization with the specific Rho kinase inhibitor Y-27632, significantly decreased SAC sensitivity in these cells, suggesting a role for Rho-dependent actin remodeling in the regulation of the channel opening. The alteration of cytoskeletal/SAC functional correlation had also deleterious effects on myogenic differentiation of C2C12 cells as judged by combined confocal immunofluorescence, biochemical and electrophysiological analyses. Indeed, the treatment with Y-27632 or with DHCB, an actin disrupting agent, inhibited the expression of the myogenic markers (myogenin and sarcomeric proteins) and myoblast-myotube transition. The treatment with the channel blocker, GdCl(3), also affected myogenesis in these cells. It impaired, in fact, myoblast phenotypic maturation (i.e., reduced the expression of alpha-sarcomeric actin and skeletal myosin and the activity of creatine kinase) but did not modify promoter activity and protein expression levels of myogenin. The results of this study, together with being in agreement with the general idea that cytoskeletal remodeling is essential for muscle differentiation, describe a novel pathway whereby the formation of SFs and their contraction, generate a mechanical tension to the plasma membrane, activate SACs and trigger Ca(2+)-dependent signals, thus influencing the phenotypic maturation of myoblasts.

Melatonin affects voltage-dependent calcium and potassium currents in MCF-7 cell line cultured either in growth or differentiation medium

“…Linear leak and capacitive currents were canceled on-line using the P/4 procedure. This procedure also minimized the not-voltage dependent currents such as those flowing through intermediate-conductance Ca 2 þ -activated K þ channels, IKCa (Haren et al, 2010), and stretch activated channels (Formigli et al, 2007;Sbrana et al, 2008).…”

“…However, to elucidate this issue, it must be considered that besides the voltage dependent ion channel activation, many other mechanisms may contribute to the establishment of resting membrane potential, such as stretch activated channels (Aydar et al, 2009;Formigli et al, 2007;Sbrana et al, 2008), ionic pumps (2Na/3 K ATPase and Ca 2 þ pump), 3Na/Ca exchanger (Becchetti 2011) and voltage-independent channels as IKCa and K ATP (Abdul et al, 2003;Blackiston et al, 2009;Haren et al, 2010;Klimatcheva and Wonderlin, 1999), and that the complexity of the scenario requires further investigations.…”

Regulation of transient receptor potential canonical channel 1 (TRPC1) by sphingosine 1-phosphate in C2C12 myoblasts and its relevance for a role of mechanotransduction in skeletal muscle differentiation

“…It has been recently reported that activation of stretch-activated channels (SACs) may also play a role in muscle biology and myogenesis (Formigli et al, 2007b;Wedhas et al, 2005). SACs are non-selective ion channels that are present in a huge variety of cells and organisms, where they participate in mechanotransduction, converting membrane stretch into electrical Ca 2+ , K + and Na + current across the plasma membrane, and biochemical signals (Ambudkar, 2006;Sachs and Morris, 1998).…”

“…SACs are non-selective ion channels that are present in a huge variety of cells and organisms, where they participate in mechanotransduction, converting membrane stretch into electrical Ca 2+ , K + and Na + current across the plasma membrane, and biochemical signals (Ambudkar, 2006;Sachs and Morris, 1998). In particular, SAC expression and activity are prevalent in neonatal skeletal muscle tissue and undifferentiated myoblasts, and decline as myoblasts mature and fuse into myotubes (Formigli et al, 2007b;Haws and Lansman, 1991). Moreover, the inhibition of these channels with several pharmacological compounds, including gadolinium chloride (GdCl 3 ), streptomycin and the spider venom toxin (GsMTx4), has been shown to suppress the expression of the typical myogenic markers and the myoblast-myotube transition, suggesting that SAC activation may lead to increased Ca 2+ entries necessary for skeletal muscle differentiation (Formigli et al, 2007b;Wedhas et al, 2005).…”

Functional interaction between TRPC1 channel and connexin-43 protein: a novel pathway underlying S1P action on skeletal myogenesis

“…S1P actions on skeletal myoblast differentiation are strictly dependent on intracellular Ca 2? mobilization [6,8,9], actin cytoskeletal remodeling, and mechanosensitive stretch-activated cation channel (SAC) opening [10,11]. The formation of stress fibers by S1P has been associated with plasma membrane stretching and, in turn, with SAC activation in C2C12 myoblasts [12,13].…”