Ubiquitin-proteasome system and ER stress in the retina of diabetic rats
Related Experiment Video
Updated: Feb 28, 2026

Alternate Immersion in Glucose to Produce Prolonged Hyperglycemia in Zebrafish
Published on: May 5, 2021
Karnam Shruthi1, Singareddy Sreenivasa Reddy1, Geereddy Bhanuprakash Reddy1
1Biochemistry Division, National Institute of Nutrition, Hyderabad, India.
Purpose:
Diabetic retinopathy (DR) is the most frequently occurring complication of diabetes. Alterations in ubiquitin-proteasome system (UPS) have been associated with several degenerative disorders. Hence, in this study, we investigated the status and role of UPS and ER stress in the retina of diabetic rats.
Methods:
Diabetes was induced in rats by streptozotocin. Retinal markers, ER stress markers, components of UPS, ERAD, and autophagy were analyzed after 2- and 4-months of diabetes. Apoptosis was analyzed by TUNEL Assay.
Results:
There were increased acellular capillaries and pericyte loss in diabetic rat retina. Decreased protein expression of UPS components - ubiquitin activating enzyme (E1), deubiquitinating enzymes (UCHL1 and UCHL5), SIAH1 (E3 ligase) and free ubiquitin were observed in the diabetic rats. Increased ER stress markers (ATF6, XBP1, and CHOP), decreased expression of HRD1, declined autophagy (LC3B) and increased apoptosis were observed in diabetic rats. Interestingly, treatment of diabetic rats with a chemical chaperone (4-PBA) restored the levels of DUBs and ameliorated ER stress-induced retinal cell death in type 1 diabetic rats.
Conclusion:
The declined UPS components: E1 and HRD1 in the retina of diabetic rats could elicit ER stress, and the prolonged ER stress may trigger CHOP-mediated neuronal apoptosis.
Related Concept Videos
Role of ER in the Secretory Pathway
Components of the secretory pathway
About a third of proteins synthesized in the cell are sorted via the secretory route. They shuffle between different compartments in membrane-bound vesicles until they reach their final destination. The main intracellular compartments involved...
The Unfolded Protein Response
Export of Misfolded Proteins out of the ER
Protein Folding Quality Check in the RER

