Melatonin-induced autophagy is associated with degradation of MyoD protein in C2C12 myoblast cells
Article first published online: 14 MAY 2012
© 2012 John Wiley & Sons A/S
Journal of Pineal Research
Volume 53, Issue 3, pages 289–297, October 2012
How to Cite
Kim, C. H., Kim, K. H. and Yoo, Y.-M. (2012), Melatonin-induced autophagy is associated with degradation of MyoD protein in C2C12 myoblast cells. Journal of Pineal Research, 53: 289–297. doi: 10.1111/j.1600-079X.2012.00998.x
- Issue published online: 10 SEP 2012
- Article first published online: 14 MAY 2012
- Accepted manuscript online: 31 MAR 2012 09:55AM EST
- Received September 29, 2011; Accepted March 23, 2012.
- C2C12 cells;
- lysosomal degradation;
Abstract: MyoD is a muscle-specific transcriptional factor that acts as a master switch for skeletal muscle differentiation. This protein regulates myoblast proliferation and myogenic differentiation and is also a short-lived regulatory protein that is degraded by the ubiquitin system. However, the lysosomal pathway of MyoD protein degradation remains unknown. In this study, we sought to determine whether melatonin (1, 2 mm)-induced autophagy causes the degradation of MyoD protein in C2C12 myoblast cells. Melatonin induced a significant increase in expression of the microtubule-associated protein 1 light chain 3 (LC3)-II and Beclin-1 proteins in a dose-dependent manner. Melatonin treatment also significantly increased p-ERK, Ras, and p-Akt expressions in a dose-dependent manner. However, Bax expression was high compared with the absence of melatonin treatment, and Bcl-2 expression was high in the 0.1–0.5 mm melatonin treatments and low in the 1 and 2 mm melatonin treatments. Under the same conditions, cytosolic MyoD protein was significantly decreased in a dose-dependent manner and completely eliminated by 36 hr. This decrease in MyoD protein involved ubiquitin-mediated proteasomal activity with proteasome inhibitor MG132 or autophagy-dependent lysosomal degradation with lysosomal inhibitor bafilomycin A1 (Baf-A1). In the same condition, phosphorylation of the mammalian target of rapamycin, p-mTOR, and p-S6K expression with Baf-A1 or Baf-A1-plus melatonin treatment were significantly decreased compared with the levels after treatment with melatonin only. Together, these results suggest that melatonin (1, 2 mm)-induced autophagy results in partial lysosomal degradation of MyoD protein in C2C12 myoblast cells.