Lycium ruthenicum Murray Anthocyanin Regulates the Molecular Mechanism of Hypoxia-Induced Calcium Homeostasis in H9c2 Cells Through the circAgtpbp1/rno-miR-30b-5p/Rgs8 Axis

Maintaining intracellular calcium (Ca²⁺) homeostasis is crucial for normal cardiomyocyte function and growth. Anthocyanins, known for their strong antioxidant properties, can neutralize free radicals and mitigate hypoxia-induced damage to cardiomyocytes. Circular RNAs (circRNAs), acting as competing endogenous RNAs (ceRNAs), regulate cellular processes under hypoxic conditions by interacting with microRNAs to influence cell differentiation, proliferation, apoptosis, and energy metabolism. However, the role of circRNAs in intracellular Ca²⁺ homeostasis remains unclear. In this study, we explored the impact of the circAgtpbp1/rno-miR-30b-5p/Rgs8 axis on the regulation of Ca²⁺ homeostasis in hypoxia-induced H9c2 cells, based on our previous findings related to anthocyanin-mediated hypoxia protection. We utilized various molecular tools, including circAgtpbp1 and Rgs8 overexpression vectors, si-RNA fragments, and rno-miR-30b-5p mimics and inhibitors, to modulate the expression of circAgtpbp1, Rgs8 and rno-miR-30b-5p. Our results indicate that inhibition of rno-miR-30b-5p, along with overexpression of circAgtpbp1 and Rgs8, disrupts the regulatory effects of anthocyanins on hypoxia-induced H9c2 cells, while promoting these effects conversely. Moreover, circAgtpbp1 and Rgs8 synergistically modulate the influence of anthocyanins on these cells, with rno-miR-30b-5p counteracting the effects of Rgs8 and circAgtpbp1. These findings suggest that anthocyanins regulate Ca²⁺ homeostasis in hypoxia-induced H9c2 cells through the circAgtpbp1/Rgs8/rno-miR-30b-5p axis and provide insights into the molecular mechanisms underlying anthocyanin-mediated hypoxia protection, thus establishing a foundation for further research on cardiac protection in hypoxic conditions.