Abstract 13942: Circular RNA-HIPK3 Suppresses Aortic Valve Calcification by Dual Inhibition of the Wnt/β-catenin Pathway in Aortic Valve Interstitial Cells

Introduction: Calcific aortic valve disease (CAVD) has become an increasingly important worldwide medical problem without effective pharmacological intervention. Circular RNAs (circRNAs), a large class of non-coding RNAs, have been shown to play a critical role in the occurrence and progression of cardiovascular disease. However, the role of circRNAs in CAVD remains unclear. Methods and Results: High-throughput sequencing of circRNAs expression profiles in human calcified aortic valves and normal controls revealed that circRNA-HIPK3 (circHIPK3) was abundant in aortic valves but decreased in calcified aortic valves. Infecting the CAVD mouse model with adeno-associated virus subtype 9 expressing circHIPK3 (AAV9-circHIPK3) revealed that circHIPK3 overexpression reduced thickness and calcium deposition of the aortic valve leaflet in vivo . Gain- or loss-of-function experiments showed that circHIPK3 inhibited osteogenic responses in human aortic valve interstitial cells. MeRIP and RIP experiments showed that circHIPK3 enhanced the stability of suppressor of morphogenesis in genitalia 1 (SMG1) mRNA in an N6-methyladenosine (m 6 A)-dependent manner. Meanwhile, RNA pull-down and ChIP-Seq indicated that circHIPK3 increased the transcriptional activity of Chibby family member 1(CBY1) by promoting TATA-box binding protein-associated factor 15 (TAF15) intranuclear translocation. Furthermore, SMG1 and CBY1 negatively regulated the activity of Wnt/β-catenin pathway, and rescue experiments showed that circHIPK3 inhibited the Wnt/β-catenin pathway through increasing the expression of SMG1 and CBY1. Conclusions: Deficiency of circHIPK3 results in activation of the Wnt/β-catenin pathway and thereby induces aortic valve calcification. Exogenous circHIPK3 supplementation shows the ability to inhibit aortic valve thickening and calcification in vivo . Therefore, targeting circHIPK3 may be a potential strategy to prevent the development of CAVD.