Aster-B Modulates Oxidative Stress Responses and Carotenoid Distribution in ARPE-19 Cells

Area of Science:

• Ocular biology
• Cellular stress response
• Lipid metabolism

Background:

• Oxidative stress and lipid metabolism are key factors in ocular diseases like drusen formation and photoreceptor damage.
• Aster-B (GRAMD1B) facilitates non-vesicular cholesterol and carotenoid transport and is abundant in the human eye, but its ocular role is unclear.

Purpose of the Study:

• To investigate the function of Aster-B in ARPE-19 cells, a model for retinal pigment epithelium (RPE).
• To understand Aster-B's role in cellular response to oxidative stress and its impact on lipid transport.

Main Methods:

• Generated an Aster-B-expressing cell line in ARPE-19 cells using CRISPR/dCas9.
• Exposed cells to hydrogen peroxide (H2O2) to induce oxidative stress.
• Tracked carotenoid localization and cellular responses under varying conditions.

Main Results:

• Aster-B expression increased ARPE-19 cell survival under H2O2-induced oxidative stress, activating p53 and TGFβ pathways.
• Aster-B facilitated mitochondrial accumulation of carotenoids, which decreased under oxidative stress.
• Carotenoids protected control cells but harmed Aster-B-expressing cells under oxidative stress, indicating context-dependent function.

Conclusions:

• Aster-B plays a crucial role in RPE cells by coordinating lipid transport and cellular stress responses.
• Findings suggest Aster-B's involvement in the pathogenesis of oxidative stress-related ocular diseases.
• Carotenoid's beneficial or detrimental effects are dependent on Aster-B expression and cellular location.