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Dexamethasone Stimulates Store-operated Calcium Entry and Protein Degradation in Cultured L6 Myotubes Through a Phospholipase A(2)-dependent Mechanism

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Specialties Cell Biology
Physiology
Date 2010 Jan 29
PMID 20107037
Citations 14
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Abstract

Muscle wasting in various catabolic conditions is at least in part regulated by glucocorticoids. Increased calcium levels have been reported in atrophying muscle. Mechanisms regulating calcium homeostasis in muscle wasting, in particular the role of glucocorticoids, are poorly understood. Here we tested the hypothesis that glucocorticoids increase intracellular calcium concentrations in skeletal muscle and stimulate store-operated calcium entry (SOCE) and that these effects of glucocorticoids may at least in part be responsible for glucocorticoid-induced protein degradation. Treatment of cultured myotubes with dexamethasone, a frequently used in vitro model of muscle wasting, resulted in increased intracellular calcium concentrations determined by fura-2 AM fluorescence measurements. When SOCE was measured by using calcium "add-back" to muscle cells after depletion of intracellular calcium stores, results showed that SOCE was increased 15-25% by dexamethasone and that this response to dexamethasone was inhibited by the store-operated calcium channel blocker BTP2. Dexamethasone treatment stimulated the activity of calcium-independent phospholipase A(2) (iPLA(2)), and dexamethasone-induced increase in SOCE was reduced by the iPLA(2) inhibitor bromoenol lactone (BEL). In additional experiments, treatment of myotubes with the store-operated calcium channel inhibitor gadolinium ion or BEL reduced dexamethasone-induced increase in protein degradation. Taken together, the results suggest that glucocorticoids increase calcium concentrations in myocytes and stimulate iPLA(2)-dependent SOCE and that glucocorticoid-induced muscle protein degradation may at least in part be regulated by increased iPLA(2) activity, SOCE, and cellular calcium levels.

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References
1.
Benson D, Hasselgren P, Hiyama D, James J, Li S, Rigel D . Effect of sepsis on calcium uptake and content in skeletal muscle and regulation in vitro by calcium of total and myofibrillar protein breakdown in control and septic muscle: results from a preliminary study. Surgery. 1989; 106(1):87-93. View

2.
Sandri M, Sandri C, Gilbert A, Skurk C, Calabria E, Picard A . Foxo transcription factors induce the atrophy-related ubiquitin ligase atrogin-1 and cause skeletal muscle atrophy. Cell. 2004; 117(3):399-412. PMC: 3619734. DOI: 10.1016/s0092-8674(04)00400-3. View

3.
Periasamy M, Kalyanasundaram A . SERCA pump isoforms: their role in calcium transport and disease. Muscle Nerve. 2007; 35(4):430-42. DOI: 10.1002/mus.20745. View

4.
Lam M, Dubyak G, Distelhorst C . Effect of glucocorticosteroid treatment on intracellular calcium homeostasis in mouse lymphoma cells. Mol Endocrinol. 1993; 7(5):686-93. DOI: 10.1210/mend.7.5.8316252. View

5.
Krozowski Z, Li K, Koyama K, Smith R, Obeyesekere V, Sasano H . The type I and type II 11beta-hydroxysteroid dehydrogenase enzymes. J Steroid Biochem Mol Biol. 1999; 69(1-6):391-401. DOI: 10.1016/s0960-0760(99)00074-6. View