Cbf mediates articular cartilage regeneration and repair in aging

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The long term goal of this study is to develop a safer and more effective therapeutic approach to cure aging- associated osteoarthritis (OA). The immediate goal of this study is to characterize the mechanism underlying how core-binding factor beta (Cbfβ) mediates articular cartilage regeneration and repair in aging-associated OA. Current therapeutic options for aging-associated OA are still limited to pain management and surgical intervention representing a significant concern in the aging population. Recent studies have shed light on the nature of OA genetic susceptibility and confirmed a number of candidate genes involved in damage of the articular cartilage, including Sox9, YAP, Wnt/β-catenin signaling and TGFβ/BMP signaling. However, the root causes of the disease remain unclear. In our preliminary studies, we found that the expression of Cbfβ decreases with age in mouse articular cartilage, while postnatal induced chondrocyte-specific Cbfβ-deficient mice developed spontaneous OA-like phenotype characterized by articular cartilage degradation and subchondral bone intrusion, which was exacerbated with age. Notably, heatmap analysis of RNA-seq data showed that Cbfβf/fCol2α1-Cre and aging mice articular cartilage share very similar changes in the gene expression profiles compared with that of two-month-old mouse articular cartilage. Our qPCR data confirmed that the OA related gene expression changes in articular cartilage of aging-associated and Cbfβ deficiency induced OA included downregulated Sox9, BMP7, ALK3 and upregulated Yap, Wnt5a/b, Wnt/β-catenin BMP2/4. In addition, AAV-CMV-Cbfβ mediated Cbfβ overexpression with local administration protected against surgical OA in mice. Based on our preliminary data, we hypothesize that deficiency of Cbfβ is one of the main causes of articular cartilage degeneration in aging-associated osteoarthritis (OA), and Cbfβ enhances articular cartilage regeneration and repair by modulating multiple key signaling pathways, including Wnt/β-catenin, BMP/TGFβ, YAP and Sox9 signaling pathways. We will test this hypothesis through three specific aims. In Aim1, We determine the roles of Cbfβ in articular cartilage regeneration and repair in aging-associated osteoarthritis through analyses of adult and aged Cbfβf/fAggrecan-CreER mice, and aged wild type mice in physiological and pathological conditions via a loss-of-function approach. In Aim 2, we characterize the function of Cbfβ in articular cartilage regeneration and repair and preventing OA genesis in adult and aged mice via a gain-of-function approach using AAV-CMV-Cbfβ and CbfβOEf/fAggrecan-CreER gene overexpression models. We will dissect the mechanism underlying how Cbfβ enhances articular cartilage regeneration and repair by regulating the Wnt/β-catenin, BMP/TGFβ, YAP, and Sox9 signaling pathways in aging-associated OA in Aim 3. Insights gained from the proposed study will not only address the basic scientific question about the pathogenesis of aging-associated OA, but also will provide the foundation for the ultimate goal of facilitating the design of safer and novel therapeutic approach for aging-associated OA.