| First Author | Semjonous NM | Year | 2011 |
| Journal | Endocrinology | Volume | 152 |
| Issue | 1 | Pages | 93-102 |
| PubMed ID | 21106871 | Mgi Jnum | J:189132 |
| Mgi Id | MGI:5444422 | Doi | 10.1210/en.2010-0957 |
| Citation | Semjonous NM, et al. (2011) Hexose-6-phosphate dehydrogenase contributes to skeletal muscle homeostasis independent of 11beta-hydroxysteroid dehydrogenase type 1. Endocrinology 152(1):93-102 |
| abstractText | Glucose-6-phosphate (G6P) metabolism by the enzyme hexose-6-phosphate dehydrogenase (H6PDH) within the sarcoplasmic reticulum lumen generates nicotinamide adenine dinucleotide phosphate (reduced) to provide the redox potential for the enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) to activate glucocorticoid (GC). H6PDH knockout (KO) mice have a switch in 11beta-HSD1 activity, resulting in GC inactivation and hypothalamic-pituitary-adrenal axis activation. Importantly, H6PDHKO mice develop a type II fiber myopathy with abnormalities in glucose metabolism and activation of the unfolded protein response (UPR). GCs play important roles in muscle physiology, and therefore, we have examined the importance of 11beta-HSD1 and GC metabolism in mediating aspects of the H6PDHKO myopathy. To achieve this, we examined 11beta-HSD1/H6PDH double-KO (DKO) mice, in which 11beta-HSD1 mediated GC inactivation is negated. In contrast to H6PDHKO mice, DKO mice GC metabolism and hypothalamic-pituitary-adrenal axis set point is similar to that observed in 11beta-HSD1KO mice. Critically, in contrast to 11beta-HSD1KO mice, DKO mice phenocopy the salient features of the H6PDHKO, displaying reduced body mass, muscle atrophy, and vacuolation of type II fiber-rich muscle, fasting hypoglycemia, increased muscle glycogen deposition, and elevated expression of UPR genes. We propose that muscle G6P metabolism through H6PDH may be as important as changes in the redox environment when considering the mechanism underlying the activation of the UPR and the ensuing myopathy in H6PDHKO and DKO mice. These data are consistent with an 11beta-HSD1-independent function for H6PDH in which sarcoplasmic reticulum G6P metabolism and nicotinamide adenine dinucleotide phosphate-(oxidized)/nicotinamide adenine dinucleotide phosphate (reduced) redox status are important for maintaining muscle homeostasis. |
