Abstract
Purpose:
Diabetes is one of the risk factors that lead to corneal keratopathy and the deficiency in epithelium wound healing is relatively common in persons with diabetes mellitus, leading to corneal ulceration and subsequent vision loss. This study investigated the promotive effects of SIRT1 on high glucose-attenuated corneal epithelial wound healing via p53 regulation of the IGFBP3/IGF-1R/AKT pathway.
Methods:
Effects of high glucose on SIRT expression were assessed in primary human corneal epithelial cells and corneas from Ins2Akita/+mice by Western blotting. SIRT1 was activated by ectopic expression. Effects of p53 as a key regulational factor and targets AKT pathway in response to high glucose induced wounding were investigated in corneal epithelial cells. Effects of overexpression of SIRT1 promotes high glucose-attenuated corneal epithelial wound healing via p53 regulation of the IGFBP3/IGF-1R/AKT pathway were investigated in corneal epithelial cells and Ins2Akita/+mice.
Results:
High glucose induces downregulation of SIRT1 and upregulation of p53 acetylation in primary human corneal epithelial cells (CECs) and corneas from Ins2Akita/+mice. Treatment with Pifithrin-α (PFT-α) dramatically decreased total p53 and acetylated p53 expression and AKT pathway was activated in CECs. Acetyl-p53 was also increased by the histone deacetylase (HDAC) class I/II inhibitor trichostatin A (TSA) and AKT pathway was inactivated. This post-translational modifications of the p53 protein was also involved in response to high glucose induced wounding in CECs, suggesting p53 as a key regulational factor and targets AKT pathway in corneal epithelium wound healing. Furthermore, SIRT1 overexpression completely promotes high glucose-attenuated wound healing in CECs and corneas from Ins2Akita/+mice with the down-regulation of IGFBP3 protein. The molecular mechanism by which SIRT1 promotes corneal epithelial wound healing appeared to involve the enhancement of IGFBP3/IGF-1/AKT pathway through deacetylation of p53.
Conclusions:
These results will provide a valuable information into the mechanisms underlying corneal epithelial cells wound healing with diabetes mellitus. This study also suggest a protective role of SIRT1 in the pathogenesis of diabetic keratopathy and the regulation of SIRT1 as a possible target to attenuate high glucose-attenuated corneal epithelial wound healing.
Keywords: 480 cornea: basic science