CircZBTB44-Encoded Peptide ZBTB44-342aa Alleviates Aortic Valve Calcification Via cGAS-STING Inhibition

BACKGROUND: Circular RNAs are implicated in various physiopathologic activities and play a crucial role in calcific aortic valve disease (CAVD) progression. However, the role of coding circular RNAs in CAVD remains unclear. In this study, we aimed to characterize coding circular RNAs and explore their functions in CAVD. METHODS: Using a systematic approach from transcriptome sequencing to experimental validation, we identified circZBTB44, confirmed its translation into ZBTB44-342aa, and investigated the function and mechanism of this peptide in CAVD using both cellular and animal models. RESULTS: We found that circZBTB44 promotes the translation of ZBTB44-342aa through N6-methyladenosine modifications. Functionally, ZBTB44-342aa binds to IGF2BP3 (insulin-like growth factor 2 mRNA-binding protein 3), which inhibits mitochondrial damage and mtDNA release into the cytoplasm, thereby suppressing the activation of the cGAS-STING (stimulator of interferon genes) pathway and alleviating the osteogenic differentiation of human aortic valve interstitial cells. Consistent with this, both circZBTB44 overexpression and STING deprivation alleviated aortic valve lesions in vivo, while in vitro, overexpressing circZBTB44 or adding ZBTB44-342aa recombinant protein inhibited the osteogenic response. Conversely, siRNA-mediated knockdown of circZBTB44 enhanced this response. Furthermore, STING inhibition by H-151 alleviated the osteogenic response, whereas its activation by dimeric amidobenzimidazole exacerbated it. CONCLUSIONS: This study demonstrates that circZBTB44-encoded ZBTB44-342aa alleviates CAVD progression by inhibiting the cGAS-STING signaling pathway, thereby identifying both circZBTB44 and STING as potential therapeutic targets.