Journal
CELLULAR SIGNALLING
Volume 28, Issue 5, Pages 384-390Publisher
ELSEVIER SCIENCE INC
DOI: 10.1016/j.cellsig.2016.01.017
Keywords
Glucosamine; Insulin; Hexosamine biosynthetic pathway; Regulated in DNA Damage and Development 1; O-GlcNAcylation; ER Stress
Categories
Funding
- American Diabetes Association Pathway to Stop Diabetes [1-14-INI-04]
- NIH [EY023612]
Ask authors/readers for more resources
Resistance to insulin action is a key cause of diabetic complications, yet much remains unknown about the molecular mechanisms that contribute to the defect. Glucose-induced insulin resistance in peripheral tissues such as the retina is mediated in part by the hexosamine biosynthetic pathway (HBP). Glucosamine (GAM), a leading dietary supplement marketed to relieve the discomfort of osteoarthritis, is metabolized by the HBP, and in doing so bypasses the rate-limiting enzyme of the pathway. Thus, exogenous GAM consumption potentially exacerbates the resistance to insulin action observed with diabetes-induced hyperglycemia. In the present study, we evaluated the effect of GAM on insulin action in retinal Muller cells in culture. Addition of GAM to Muller cell culture repressed insulin-induced activation of the Akt/mTORC1 signaling pathway. However, the effect was not recapitulated by chemical inhibition to promote protein O-GlcNAcylation, nor was blockade of O-GlcNAcylation sufficient to prevent the effects of GAM. Instead, GAM induced ER stress and subsequent expression of the protein Regulated in DNA Damage and Development (REDD1), which was necessary for GAM to repress insulin stimulated phosphorylation of Akt on Thr308. Overall, the findings support a model whereby GAM promotes ER stress in retinal Muller cells, resulting in elevated REDD1 expression and thus resistance to insulin action. (C) 2016 Elsevier Inc. All tights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available