Circ_CLASP2 Regulates High Glucose-Induced Dysfunction of Human Endothelial Cells Through Targeting miR-140-5p/FBXW7 Axis

Abstract

Hyperglycemia exposure results in the dysfunction of endothelial cells (ECs) and the development of diabetic complications. Circular RNAs (circRNAs) have been demonstrated to play critical roles in EC dysfunction. The current study aimed to explore the role and mechanism of circRNA CLIP–associating protein 2 (circ_CLASP2, hsa_circ_0064772) on HG-induced dysfunction in human umbilical vein endothelial cells (HUVECs). Quantitative real-time polymerase chain reaction (qRT-PCR) was used to assess the levels of circ_CLASP2, miR-140-5p and F-box, and WD repeat domain-containing 7 (FBXW7). The stability of circ_CLASP2 was identified by the actinomycin D and ribonuclease (RNase) R assays. Cell colony formation, proliferation, and apoptosis were measured by a standard colony formation assay, colorimetric 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl-2H-tetrazolium bromide (MTT) assay, and flow cytometry, respectively. Western blot analysis was performed to determine the expression of related proteins. Targeted correlations among circ_CLASP2, miR-140-5p, and FBXW7 were confirmed by dual-luciferase reporter assay. High glucose (HG) exposure downregulated the expression of circ_CLASP2 in HUVECs. Circ_CLASP2 overexpression or miR-140-5p knockdown promoted proliferation and inhibited apoptosis of HUVECs under HG conditions. Circ_CLASP2 directly interacted with miR-140-5p via pairing to miR-140-5p. The regulation of circ_CLASP2 overexpression on HG-induced HUVEC dysfunction was mediated by miR-140-5p. Moreover, FBXW7 was a direct target of miR-140-5p, and miR-140-5p regulated HG-induced HUVEC dysfunction via FBXW7. Furthermore, circ_CLASP2 mediated FBXW7 expression through sponging miR-140-5p. Our current study suggested that the overexpression of circ_CLASP2 protected HUVEC from HG-induced dysfunction at least partly through the regulation of the miR-140-5p/FBXW7 axis, highlighting a novel therapeutic approach for the treatment of diabetic-associated vascular injury.

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

“…In contrast, it has been demonstrated that circ_CLASP2 is decreased in HG-induced HUVECs. Circ_CLASP2 protects HUVECs against hyperglycemia dysfunction by regulating the miR-140-5p/FBXW7 pathway ( Zhang et al, 2021b ).…”

Recent Insight on Regulations of FBXW7 and Its Role in Immunotherapy

“…Parallel to lncRNAs, most circRNAs regulate FBXW7 as miRNA "sponges". For instance, hsa_circ_11780 (93), circFBXW4 (94), Hsa_circ_001988 (95), circ_CLASP2 (96), circBRAF (97), circ_0000094 (98), hsa_circ_0001306 (99), hsa_circ_0022742 (100), circPSD3 (101), and circKL (102) were confirmed to sponge different miRNAs to impact the expression of FBXW7, respectively. Intriguingly, although the majority of circRNAs are deemed unable to code proteins as non-coding RNAs, a special circRNA associated with FBXW7 has been confirmed the function of coding protein.…”

Hyperglycemia-induced endothelial exosomes trigger trophoblast dysregulation and abnormal placentation through PUM2-mediated repression of SOX2

“…Glucose concentrations between 20 to 30 mmol/l have been used to mimic high-glucose conditions in previous studies. [25][26][27][28] Our experiments were conducted in cells treated by NG (5 mmol/l), HG (20 mmol/l), HG (30 mmol/l) and mannitol as an osmotic control for more rigorous study design and careful conclusions. We labeled HUVECderived exosomes with DiD fluorescent probes and uptake of the labeled exosomes by HTR-8a/SVneo cells was certified by immuno-fluorescent imaging.…”