HuD and alpha-crystallin A axis protects neuro-retinal cells in early diabetes

TL;DR

This study shows that the HuD and CRYAA proteins protect retinal cells in early diabetes, offering new insights into preventing neuro-retinal damage.

Contribution

The study identifies HuD as a novel regulator of CRYAA, revealing a new protective axis in diabetic neuro-retinal degeneration.

Findings

HuD and CRYAA are downregulated in diabetic retinas and high-glucose-treated cells.

HuD regulates CRYAA by binding to its mRNA, affecting cell viability and inflammation.

Modulating HuD and CRYAA levels impacts cell death under hyperglycemic conditions.

Abstract

Diabetic retinopathy (DR) is a prevalent microvascular complication of diabetes; however, neuro-retinal degeneration is also observed in patients with diabetes without signs of DR. The mechanisms leading to neuro-retinal cell loss before vascular complications manifest in diabetes remain poorly understood. In this study, we investigated the neuronal RNA-binding protein HuD as a novel regulator of neuro-retinal degeneration in the early stage of diabetes. We determined the expression of HuD and alpha-crystallin A (CRYAA) in the retinal ganglion cell layer. HuD and CRYAA were down-regulated in the retinas of streptozotocin-induced diabetic rats and in neuro-retinal cells (R-28) treated with high glucose. Cryaa mRNA was identified as a novel target transcript of HuD, and we demonstrated that HuD post-transcriptionally regulates the expression of Cryaa mRNA by binding to its 3′-untranslated region. Silencing and overexpression of HuD positively regulated the expressions of Cryaa mRNA and protein. We demonstrated that the increase in inflammatory cytokines such as TNFα, IL-1β, and IL-6 in R-28 cells under hyperglycemic conditions was a result of both CRYAA and HuD levels. Silencing HuD and CRYAA enhanced high glucose-induced R-28 cell death, whereas their overexpression alleviated this effect. HuD post-transcriptionally regulates CRYAA expression, influencing the function and viability of neuro-retinal cells under diabetic conditions. Our results suggest that the HuD/CRYAA axis plays a crucial role in neuro-retinal cells and has the potential to serve as a prognostic factor and therapeutic target for diabetic neuro-retinal degeneration.

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