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 (Cbf?) 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/?-catenin signaling and TGF?/BMP signaling. However, the root causes of the disease remain unclear. In our preliminary studies, we found that the expression of Cbf? decreases with age in mouse articular cartilage, while postnatal induced chondrocyte-specific Cbf?-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 Cbf?f/fCol2?1-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 Cbf? deficiency induced OA included downregulated Sox9, BMP7, ALK3 and upregulated Yap, Wnt5a/b, Wnt/?-catenin BMP2/4. In addition, AAV-CMV-Cbf? mediated Cbf? overexpression with local administration protected against surgical OA in mice. Based on our preliminary data, we hypothesize that deficiency of Cbf? is one of the main causes of articular cartilage degeneration in aging-associated osteoarthritis (OA), and Cbf? enhances articular cartilage regeneration and repair by modulating multiple key signaling pathways, including Wnt/?-catenin, BMP/TGF?, YAP and Sox9 signaling pathways. We will test this hypothesis through three specific aims.
In Aim1, We determine the roles of Cbf? in articular cartilage regeneration and repair in aging-associated osteoarthritis through analyses of adult and aged Cbf?f/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 Cbf? in articular cartilage regeneration and repair and preventing OA genesis in adult and aged mice via a gain-of-function approach using AAV-CMV-Cbf? and Cbf?OEf/fAggrecan-CreER gene overexpression models. We will dissect the mechanism underlying how Cbf? enhances articular cartilage regeneration and repair by regulating the Wnt/?-catenin, BMP/TGF?, 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.
Osteoarthritis (OA) is the most common form of arthritis affecting the knee, hip and spine, inflicting pain and physical limitation on over 70% of Americans between the age of 55 and 70. The proposed study will provide important insights into the roles of Cbf? in aging-associated OA by elucidating the mechanism by which Cbf? regulates Sox9, Yap, Wnt/?-catenin, BMP/TGF? signaling and articular cartilage regeneration and repair. 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.