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mTORC1-Independent Reduction of Retinal Protein Synthesis in Type 1 Diabetes

Authors :
Leonard S. Jefferson
Subramaniam Pennathur
Patrice Fort
Scot R. Kimball
Mandy K. Losiewicz
Steven F. Abcouwer
Thomas W. Gardner
Source :
Diabetes
Publication Year :
2014
Publisher :
American Diabetes Association, 2014.

Abstract

Poorly controlled diabetes has long been known as a catabolic disorder with profound loss of muscle and fat body mass resulting from a simultaneous reduction in protein synthesis and enhanced protein degradation. By contrast, retinal structure is largely maintained during diabetes despite reduced Akt activity and increased rate of cell death. Therefore, we hypothesized that retinal protein turnover is regulated differently than in other insulin-sensitive tissues, such as skeletal muscle. Ins2Akita diabetic mice and streptozotocin-induced diabetic rats exhibited marked reductions in retinal protein synthesis matched by a concomitant reduction in retinal protein degradation associated with preserved retinal mass and protein content. The reduction in protein synthesis depended on both hyperglycemia and insulin deficiency, but protein degradation was only reversed by normalization of hyperglycemia. The reduction in protein synthesis was associated with diminished protein translation efficiency but, surprisingly, not with reduced activity of the mTORC1/S6K1/4E-BP1 pathway. Instead, diabetes induced a specific reduction of mTORC2 complex activity. These findings reveal distinctive responses of diabetes-induced retinal protein turnover compared with muscle and liver that may provide a new means to ameliorate diabetic retinopathy.

Details

ISSN :
1939327X and 00121797
Volume :
63
Database :
OpenAIRE
Journal :
Diabetes
Accession number :
edsair.doi.dedup.....3c73480949dbdeea316d905389b22b3c
Full Text :
https://doi.org/10.2337/db14-0235