Glucocorticoid actions on L6 muscle cells in culture
Glucocorticoids exert striking catabolic effects on skeletal muscle. The mechanism of these effects remains poorly understood. They employed L6 muscle cells in culture to ascertain whether intracellular glucocorticoid receptors are involved. Studies in vitro permit exploration of glucocorticoid effects in the absence of other hormonal influences. L6 myoblasts were induced to form differentiated myotubes by growth in 1% serum. L6 myotubes were found to possess a high-affinity, limited capacity intracellular glucocorticoid receptor (apparent K/sub D/ = 5 x 10/sup -10/ M; B/sub max/ = 711 pmols/g protein) with ligand specificity similar to that of glucocorticoid receptors from classical glucocorticoid target tissues. Further, (/sup 3/H) triamcinolone acetonide specific binding to L6 cell homogenates was blocked by a glucocorticoid antagonist, RU38486 (11..beta..-(4-dimethyl-aminophenyl)-17..beta..-hydroxy-17..cap alpha..-(prop-l-ynyl)-estra-4,9-dien-3-one). Dexamethasone (10/sup -5/M) caused a 10-fold increase in the activity of gluatmine synthetase in L6 myotubes; this increase was prevented by RU38486. Similarly, dexamethasone (10/sup -5/M) caused a 20% decrease in (/sup 12/C) leucine incorporation into protein. This effect also was blocked by RU38486. Thus, induction of glutamine synthetase and diminution of protein synthesis by dexamethasone require intracellular glucocorticoid receptors. L6 cells should prove particularly valuable for further studies of glucocorticoid actions on skeletal muscle.
- Research Organization:
- Univ. of Maryland School of Medicine, Baltimore
- OSTI ID:
- 7189688
- Report Number(s):
- CONF-8606151-
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:6; Conference: 76. annual meeting of the Federation of American Society for Experimental Biology, Washington, DC, USA, 8 Jun 1986
- Country of Publication:
- United States
- Language:
- English
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550201* - Biochemistry- Tracer Techniques