Circ-ADAM9 Promotes High Glucose-Induced Retinal Pigment Epithelial Cell Injury in DR via Regulating miR-338-3p/CARM1 Axis

Abstract

Background. Circular RNAs (circRNAs) have been reported to be involved in the regulation of retinal pigment epithelial (RPE) cell injury and are closely related to the development of diabetic retinopathy (DR). More research is needed to confirm the role and mechanism of circ-ADAM9 in DR progression. Methods. High glucose (HG)-induced RPE cells (ARPE-19) were used to mimic the hyperglycemia condition. The expression of circ-ADAM9, microRNA (miR)-338-3p, and coactivator-associated arginine methyltransferase 1 (CARM1) was measured using quantitative real-time PCR. Cell proliferation and apoptosis were determined using MTT assay, EdU assay, and flow cytometry. The protein expression of apoptosis markers and CARM1 was examined by the western blot analysis. Also, MDA level and SOD activity were determined to assess cell oxidative stress. In addition, the interaction between miR-338-3p and circ-ADAM9 or CARM1 was confirmed by dual-luciferase reporter assay and RIP assay. Results. The expression of circ-ADAM9 was upregulated in DR patients and HG-induced ARPE-19 cells. Silenced circ-ADAM9 could promote proliferation and inhibit inflammation, apoptosis, and oxidative stress in HG-induced ARPE9 cells. In terms of mechanism, circ-ADAM9 could sponge miR-338-3p to upregulate CARM1. The inhibitory effect of circ-ADAM9 knockdown on HG-induced ARPE9 cell injury could be reversed by an miR-338-3p inhibitor. As a target of miR-338-3p, CARM1 knockdown could alleviate HG-induced ARPE9 cells’ injury, and its overexpression also could reverse the negatively regulation of miR-338-3p on HG-induced ARPE9 cell injury. Conclusion. Circ-ADAM9 contributed to HG-induced ARPE9 cell injury by regulating miR-338-3p/CARM1 axis, which provided effective targets for DR treatment.

Circular RNAs in diabetes and its complications: Current knowledge and future prospects

“…Meanwhile, deficiency of circRNA _0084043 effectively suppressed HG-stimulated inflammation by inhibiting the inflammatory cytokines TNF-α, IL-6, and Cox-2 in ARPE-19 cells (Li et al, 2020b). Circ-ADAM9 and circ-PSEN1 were also up-regulated in DR, circ-ADAM9 could promote ARPE-19 cell injury and downregulation of circ-PSEN1 can ameliorate ferroptosis (Zhu et al, 2021b;Liang et al, 2022). CircZNF532 not only regulates pericyte biology by acting as a miR-29a-3p sponge and inducing increased expression of NG2, LOXL2, and CDK2, but also modulates ARPE-19 cell apoptosis and pyroptosis, thereby facilitating angiogenesis and inflammation in DR (Jiang et al, 2020;Liang et al, 2021b;Wang et al, 2022b).…”

Oxidative Stress and Its Regulation in Diabetic Retinopathy

“…Circular RNAs have also been implicated in the pathophysiology of oxidative damage in diabetic retinopathy [ 191 , 192 , 193 , 194 ]. Studies demonstrated ceRNA activity of three separate circRNA, i.e., circFTO (targeting miR-148-3p in ARPE-19), circSLC16A12 (targeting miR-140-3p in HREC), and circRNA_0084043 (targeting miR-140-3p in ARPE-19), and knockdown of these circRNAs reduced MDA content and increased SOD and/or glutathione peroxidase activity, indicating a reduction in oxidative stress [ 195 , 196 , 197 ].…”

Circular RNA circADAM9 Promotes Inflammation, Oxidative Stress, and Fibrosis of Human Mesangial Cells via the Keap1-Nrf2 Pathway in Diabetic Nephropathy

“…CircADAM9 plays an oncogenic role by regulating the proliferation, apoptosis, migration, and invasion of cancer cells in melanoma [14][15][16] and osteosarcoma [17]. CircADAM9 has also been implicated in diabetic retinopathy and is involved in the regulation of retinal pigment epithelial cell damage, including cell proliferation, apoptosis, inflammation, and oxidative stress [18][19][20]. However, the expression and role of this circRNA in DN remain largely unknown.…”