ADAR1 plays a protective role in proximal tubular cells under high glucose conditions by attenuating the PI3K/AKT/mTOR signaling pathway.

Abstract

Adenosine deaminases acting on RNA 1 (ADAR1), an RNA editing enzyme, holds a role in cancer, inflammation, and immunity. However, its specific function in the nephropathy and high-glucose-induced human renal tubular epithelial cells (HK-2) injury in diabetic db/db mice is not clear. This study explored the expression characteristics of ADAR1 in proximal renal tubular cells of diabetic db/db mice, examining its function in the mechanism of high-glucose-induced HK-2 cell injury. Furthermore, it elucidated the molecular mechanism underlying the protective effect of ADAR1, the regulation of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PKB/Akt)/mammalian target of the rapamycin (mTOR) signaling. We observed a decrease in ADAR1 expression in proximal tubular cells of diabetic db/db mice, accompanied by an increase in the expression of inflammation-related markers (PI3K/AKT/mTOR). We constructed and validated ADAR1-overexpression plasmids and used an ADAR1 inhibitor (8-azaadenosine) to carry out cell experiments. The upregulation of ADAR1 expression alleviated high-glucose-induced endoplasmic reticulum stress, reduced HK-2 cell apoptosis, and reduced the expression of inflammation-related indicators (PI3K/AKT/mTOR). Taken together, the pivotal roles of ADAR1 in the progression of proximal renal tubulopathy and the mechanism of high-glucose-induced HK-2 injury in diabetic db/db mice suggest that ADAR1 may be a potential key factor in slowing the progression of diabetic kidney disease.