Negative modulation of inositol 1,4,5-trisphosphate type 1 receptor expression prevents dystrophin-deficient muscle cells death

Abstract

Evidence for a modulatory effect of cyclosporin A (CsA) on calcium signaling and cell survival in dystrophin-deficient cells is presented. Our previous works strongly supported the hypothesis of an overactivation of Ca 2ϩ release via inositol 1,4,5-trisphosphate (IP3) receptors (IP3R) in dystrophindeficient cells, both during membrane depolarization and at rest, through spontaneous Ca 2ϩ release events. Forced expression of minidystrophin in these cells contributed, during stimulation and in resting condition, to the recovery of a controlled calcium homeostasis. In the present work, we demonstrate that CsA exposure displayed a dualmodulator effect on calcium signaling in dystrophin-deficient cells. Short-time incubation induced a decrease of IP3-dependent calcium release, leading to patterns of release similar to those observed in myotubes expressing mini-dystrophin, whereas long-time incubation reduced the expression of the type I of IP3 receptors (IP3R-1) RNA levels. Moreover, both IP3R-1 knockdown and blockade through 2-aminoethoxydiphenyle borate or CsA induced improved survival of dystrophin-deficient myotubes, demonstrating the cell death dependence on the IP3-dependent calcium signaling as well as the protective effect of CsA. Inhibition of the IP3 pathway could be a very interesting approach for reducing the natural cell death of dystrophindeficient cells in development. calcium regulation; cyclosporin A; muscular dystrophy DUCHENNE MUSCULAR DYSTROPHY (DMD) is a severe X-linked recessive, progressive muscle-wasting disease affecting 1/3,500 male births. A milder form of the disease, Becker muscular dystrophy (BMD), has a later onset and a much longer survival. Both disorders are caused by mutations in the DMD gene that encodes a 427-kDa cytoskeletal protein dystrophin expressed at the inner surface of the sarcolemma of muscle fibers (26). The vast majority of DMD mutations results in the absence of dystrophin in all muscle fibers, apart from the sporadic "revertant" fibers (49), whereas the presence of a low level of a 229-kDa truncated protein mini-dystrophin is seen in BMD patients (20).Perturbations in intracellular calcium homeostasis are thought to come with DMD. Indications suggesting such calcium alterations were discovered early before dystrophin protein was identified (16), and it was then proposed that the absence of dystrophin leads to increased levels of intracellular calcium (11), contributing to muscle degeneration through activation of calcium-dependent proteases. Further data progressively reinforced such a hypothesis. Elevated subsarcolemmal calcium levels were found in mdx muscle cells using direct measurements (6) and as well as the exploration of calciumactivated K ϩ -channels activities (32). It has been also hypothesized that calcium entry due to increased microdisruptions in dystrophic muscle cells results in an alteration of calcium leak channels. First, a local exocytotic response induced by calcium influx from a membrane wound could increase the amount of calcium leak channels (...

Inositol 1,4,5-trisphosphate (IP3)-dependent Ca2+ signaling mediates delayed myogenesis in Duchenne muscular dystrophy fetal muscle

“…In adult muscles, dystrophin and α-syntrophin regulate PLC activity by stabilizing the sarcolemma; thus, dystrophin absence leads to increased PLC activity (Jordan et al, 2004;Mondin et al, 2009;Sabourin et al, 2012). Furthermore, previous studies showed that dystrophic human samples and murine cell lines expressed high levels of IP3 compared with normal cell lines (Liberona et al, 1998;Mondin et al, 2009) and IP3-induced Ca 2+ release altered gene expression regulation (Powell et al, 2001;Araya et al, 2003).…”

“…In adult muscles, dystrophin and α-syntrophin regulate PLC activity by stabilizing the sarcolemma; thus, dystrophin absence leads to increased PLC activity (Jordan et al, 2004;Mondin et al, 2009;Sabourin et al, 2012). Furthermore, previous studies showed that dystrophic human samples and murine cell lines expressed high levels of IP3 compared with normal cell lines (Liberona et al, 1998;Mondin et al, 2009) and IP3-induced Ca 2+ release altered gene expression regulation (Powell et al, 2001;Araya et al, 2003). In addition, it was determined that modifications in the metabolism of IP3 were fundamental at different stages of muscle development (Carrasco et al, 1997), and others suggested a role for IP3/IP3R during skeletal myocyte development (Rosemblit et al, 1999) and in cardiomyocyte hypertrophy (Arantes et al, 2012).…”

“…Moreover, a previous study showed that basal levels of IP3 were increased two-to three-fold in dystrophic human and murine cell lines compared with normal cell lines (Liberona et al, 1998). As IP3 production is induced by phospholipase C (PLC) activation, it was reported that dystrophin absence determines increased PLC activity and IP3 production (Mondin et al, 2009;Sabourin et al, 2012).…”

Type 1 Inositol (1,4,5)-Trisphosphate Receptor Activates Ryanodine Receptor 1 to Mediate Calcium Spark Signaling in Adult Mammalian Skeletal Muscle

“…Several studies showed that the pathological consequence of altered Ca 2ϩ signals observed in the dystrophic skeletal muscle fibers was associated with abnormal IP 3 R distribution (36,37). Knockdown of IP 3 R1 could minimize cell death in dystrophin-deficient muscle fibers (38). Our previous studies showed that Ca 2ϩ spark in the dystrophic (mdx) muscle fibers was irreversible and no longer peripherally confined (4).…”

Ca2+-dependent Transcriptional Control of Ca2+ Homeostasis

“…In a seminal study performed in cerebellar granules, Carafoli and co-workers (33) found that expression of IP 3 R1 was induced after membrane depolarization with potassium, whereas RyR2 levels remained unchanged. The induction of IP 3 R1 was absolutely dependent on Ca also in skeletal muscle (34), although the mechanism is still unresolved because no NFAT-binding sites have been identified in the IP 3 R1 promoter (35), suggesting that the IP 3 R1 gene might be an indirect target of activity-dependent gene transcription through the calcineurin/NFAT pathway.…”