DJ-1 Promotes Diabetic Corneal Epithelial Wound Healing by Attenuating Hyperglycemia-Induced Oxidative Stress Through Inhibiting PTEN.

Abstract

Purpose: Diabetic keratopathy (DK) is characterized by delayed corneal epithelial wound healing and impaired nerve regeneration, primarily due to mitochondrial oxidative stress. DJ-1 plays a key role in redox regulation. This study explores the effects of DJ-1 downregulation on DK and its mechanisms.

Methods: Type 1 diabetes was induced in male C57BL/6J mice, and DJ-1 was overexpressed. Corneal oxidative stress and activity were assessed using DHE, Ki67, and TUNEL staining. Epithelial repair and nerve regeneration were evaluated by epithelial wound healing and nerve staining. Human corneal epithelial cells (HCE-T) and primary human corneal epithelial cells were exposed to high-glucose conditions, while DJ-1 and phosphatase and tensin homolog (PTEN) expression were modulated in HCE-T cells. Mitochondrial alterations were assessed by transmission electron microscopy, mitochondrial membrane potential staining, and mitoSOX staining. DJ-1, PTEN, and antioxidant protein levels were measured by immunofluorescence and Western blotting.

Results: In diabetic mice and high glucose-treated cells, DJ-1 and antioxidant enzyme levels were significantly reduced, while PTEN expression increased, accompanied by mitochondrial structural and functional impairments. DJ-1 overexpression alleviated oxidative stress and apoptosis, enhanced cell proliferation, and promoted epithelial wound healing and nerve regeneration. In HCE-T cells, DJ-1 downregulated PTEN, upregulated antioxidant proteins, and restored mitochondrial function, reducing reactive oxygen species accumulation and activity loss caused by high glucose. PTEN activation under high glucose diminished DJ-1's protective effects. DJ-1 also directly interacted with PTEN, indicating a regulatory mechanism.

Conclusions: DJ-1 deficiency disrupts mitochondrial function, upregulates PTEN, and suppresses antioxidant protein expression, exacerbating corneal oxidative stress. These findings provide insights into molecular mechanisms underlying DK.