Contribution of TRPC Channels to Intracellular Ca2 + Dyshomeostasis in Smooth Muscle From mdx Mice

Abstract

Duchenne muscular dystrophy (DMD) is an irreversible muscle disease characterized by a progressive loss of muscle function, decreased ambulation, and ultimately death as a result of cardiac or respiratory failure. DMD is caused by the lack of dystrophin, a protein that is important for membrane stability and signaling in excitable cells. Although vascular smooth muscle cells (VSMCs) dysfunction occurs in many pathological conditions, little is known about vascular smooth muscle function in DMD. We have previously shown that striated muscle cells, as well as neurons isolated from dystrophic (mdx) mice have higher intracellular Ca 2+ ([Ca 2+ ] i) and Na + ([Na + ] i) concentrations and decreased cell viability in comparison with wild type (Wt). Experiments were carried out in isolated VSMCs from mdx (a murine model of DMD) and congenic C57BL/10SnJ Wt mice. We found elevated [Ca 2+ ] i and [Na + ] i in VSMCs from mdx mice compared to Wt. Exposure to 1-oleoyl-2-acetyl-sn-glycerol (OAG), a TRPC3 and TRPC6 channel activator, induced a greater elevation of [Ca 2+ ] i and [Na + ] i in mdx than Wt VSMCs. The OAG induced increases in [Ca 2+ ] i could be abolished by either removal of extracellular Ca 2+ or by SAR7334, a blocker of TRPC3 and TRPC 6 channels in both genotypes. Mdx and Wt VSMCs were susceptible to muscle cell stretch-induced elevations of [Ca 2+ ] i and [Na + ] i which was completely inhibited by GsMTx-4, a mechanosensitive ion channel inhibitor. Western blots showed a significant upregulation of TRPC1-3,-6 proteins in mdx VSMCs compare to age-matched Wt. The lack of dystrophin in mdx VSMCs produced a profound alteration of [Ca 2+ ] i and [Na + ] i homeostasis that appears to be mediated by TRPC channels. Moreover, we have been able to demonstrate pharmacologically that the enhanced stretch-induced elevation of intracellular [Ca 2+ ] and concomitant cell damage in mdx VSMCs also appears to be mediated through TRPC1,-3 and-6 channel activation.

Senescence Is Associated With Elevated Intracellular Resting [Ca2 +] in Mice Skeletal Muscle Fibers. An in vivo Study

“…This pathway's identity is not fully understood; however, the involvement of TRPCs, which are highly expressed in skeletal muscle cells, has been suggested (Vandebrouck et al, 2002;Millay et al, 2009). A similar aberrant elevation in [Ca 2+ ] i and [Na + ] i have been observed in muscle cells from patients with Duchene's muscular dystrophy and mdx mice (Lopez et al, 1987;Altamirano et al, 2014b;Lopez et al, 2017Lopez et al, , 2020 where an abnormal Ca 2+ influx has also been reported (Tutdibi et al, 1999;Kruger et al, 2008;Millay et al, 2009). Thus, if it were possible to prevent this chronic elevation of [Ca 2+ ] i during aging, it may exert a myo-protective effect and potentially prevent the muscle wasting and dysfunction observed in the aging muscle.…”

“…Among the TRPCs, in skeletal muscle, TRPC3 is the most expressed, followed by TRPC1 and TRPC6 ( Kunert-Keil et al, 2006 ). TRPC channels have been implicated in the pathogenesis of diverse muscle diseases, in particular muscle dystrophies and myasthenia gravis ( Kruger et al, 2008 ; Gailly, 2012 ; Mijares et al, 2014 ; Sauc and Frieden, 2017 ; Lopez et al, 2020 ). Furthermore, overexpression of a dominant-negative form of TRPC6 (dnTRPC6) in this TRPC3 overexpression background reverted its dystrophic phenotype as well as reverting the dystrophic phenotype both in mdx and in Scgd mouse ( Millay et al, 2009 ; Burr et al, 2014 ).…”

“…Through the aid of a stereomicroscope (233445 Olympus, MA, United States), individual muscle fibers were impaled with either Ca 2+ or Na + double-barreled microelectrodes. Examples of actual recordings from these electrodes can be found in our previous publications ( Lopez et al, 1983 , 2000 , 2011 , 2020 ).…”

Abnormal Calcium Handling in Duchenne Muscular Dystrophy: Mechanisms and Potential Therapies

“…These studies show that in dystrophic colonic muscle, increased Ca 2+ influx through Ltype voltage-dependent channels is responsible for the sustained mechanical tone. A recent study showed that the enhanced stretch-induced Ca 2+ i concentration in the vascular smooth muscle cells of mdx mice occurs through the activation of TRPC1, TRPC3, and TRPC6 channels (Lopez et al, 2020). Thus, focusing on the Ca 2+ handling in dystrophic smooth muscle cells may have therapeutic implications.…”

Therapeutic effects of SKF-96365 on murine allergic rhinitis induced by OVA

“… 11 – 13 There is ample evidence that SKF-96365 is widely used to study the function of TRPC channels. 12 – 17 Previous reports indicate that SKF 96365 could suppress cardiomyocyte hypertrophy, and inhibit spontaneous nociception and pain hypersensitivity induced by melittin via inactivating TRPC channels and Ca 2+ influx. 12 , 18 In cultured NECs, TRPC6, STIM1, Orai1, Ca 2+ MFI levels, and inflammatory mediators were upregulated by lipopolysaccharide (LPS) and 1-oleoyl-2-acetyl-glycerol (OAG, diacylglycerol (DAG) analog, TRPC6 activator), but were inhibited by SKF-96365.…”