Orphan Nuclear Receptor NR4A1 Promotes Proliferation and Osteogenic Differentiation of Valvular Interstitial Cells through Activation of CCND2

Calcific aortic valve disease (CAVD), the most common human valve disease on a global scale, ranks and persists as an unaddressed clinical challenge. This is primarily attributed to the absence of efficacious pharmacological approaches. The Nuclear Receptor Subfamily 4 Group A Member 1 (NR4A1), intricately associated with the pathogenesis of multiple cardiovascular diseases, has emerged as a pivotal target for the diagnosis and treatment of numerous ailments. However, the specific molecular mechanisms and the functional significance of NR4A1 in the pathogenesis of CAVD are yet to be comprehensively elucidated. By performing in-depth analyses on human aortic valve tissues and carrying out functional investigations using primary valvular interstitial cells (VICs), we were able to demonstrate that NR4A1 significantly facilitated cellular proliferation and intensifies the osteogenic differentiation process of VICs. Evidently, this is reflected in the elevated expression of key osteogenic markers, namely runt-related transcription factor 2 (RUNX2) and alkaline phosphatase (ALP). Mechanistically, the pro-calcific effects were achieved via NR4A1-dependent modulation of the cell cycle regulatory protein Cyclin D2 (CCND2). Significantly, in vivo investigations employing ApoE-/- mice maintained on a high-fat Western diet demonstrated that pharmacological suppression of NR4A1 efficiently mitigated the advancement of aortic valve calcification. These discoveries not merely determine NR4A1 to be a crucial modulator in cellular proliferation, thereby accelerating valvular calcification, but also present compelling evidence advocating for targeting NR4A1 may represent a potential therapeutic strategy for CAVD.