Project description:Chondrocyte senescence underlies osteoarthritis (OA). However, the pathogenesis of chondrocyte senescence remains largely unclear. Here we report that TRIM15 is a critical regulator in chondrocyte senescence. TIRM15 is highly expressed in chondrocytes of senescent cartilage from human OA patients and aged mice. Using gain- and loss-of-function studies, we further identify that TRIM15 facilitates chondrocyte senescence. Notably, conditional deletion of TRIM15 in chondrocytes severely impairs skeletal growth, partially due to the fact that embryonic chondrocyte senescence is disturbed. Compared with Col2a1-CreERT2/TRIM15flox/flox mice, TRIM15flox/flox mice exhibits accelerated OA phenotype, increased senescence markers and senescence-associated secretory phenotype (SASP) during aging. Mechanistically, TRIM15 binds with YAP and directly mediates K48-linked YAP ubiquitination at K254, which interrupts the interaction between YAP and AMOT, leading to enhanced YAP nuclear translocation. Intra-articular injection of AAV5-Trim15 shRNA decelerates OA progression in mice. Collectively, these findings indicate that targeting TRIM15 reshapes aging cartilage microenvironment and protects against OA.
Project description:Cartilage aging is a quintessential feature of knee osteoarthritis, and extracellular matrix (ECM) stiffening is a typical feature of cartilage aging. However, the mechanism of ECM stiffening to influence chondrocytes and downstream molecules is still poorly understood. Here, we mimicked the physiological and pathological stiffness of human cartilage by using polydimethylsiloxane-based substrates. We show that the epigenetic regulation of Parkin by histone deacetylase 3 (HDAC3) represents a new mechanosensitive mechanism by which the stiff matrix affects the physiology of chondrocytes. We found that ECM stiffening could accelerate the senescence of cultured chondrocytes in vitro, and also found that stiff ECM downregulated HDAC3, drove Parkin acetylation to activate excessive mitophagy, and accelerated chondrocyte senescence and osteoarthritis in mice. In contrast, intra-articular injection of adeno-associated virus expressing HDAC3 restored the young phenotype of aged chondrocytes stimulated by ECM stiffening and alleviated osteoarthritis in mice. Our findings indicate that changes in the mechanical properties of ECM initiate pathogenic mechanotransduction signals, promote the acetylation of Parkin and hyperactivate mitophagy, and damage the health of chondrocytes. These findings may provide new insights into how the mechanical properties of ECM regulate chondrocytes.
Project description:Osteoarthritis (OA) is a prevalent degenerative joint disease characterized by progressive cartilage degradation, chronic inflammation, and chondrocyte senescence. Tumor necrosis factor-like cytokine 1A (TL1A), a member of the TNF superfamily, has recently been implicated in regulating inflammatory processes and tissue remodeling. However, its precise role in OA pathogenesis remains incompletely understood. In this study, we investigated the impact of TL1A deficiency on OA progression and its underlying mechanism with a focus on oxidative stress-induced chondrocyte senescence.
Project description:Osteoarthritis (OA) is a prevalent degenerative joint disease characterized by progressive cartilage degradation, chronic inflammation, and chondrocyte senescence. Tumor necrosis factor-like cytokine 1A (TL1A), a member of the TNF superfamily, has recently been implicated in regulating inflammatory processes and tissue remodeling. However, its precise role in OA pathogenesis remains incompletely understood. In this study, we investigated the impact of TL1A deficiency on OA progression and its underlying mechanism with a focus on oxidative stress-induced chondrocyte senescence.
Project description:As the unique cell type in articular cartilage, chondrocyte senescence is a crucial cellular event contributing to osteoarthritis development. Here we show that clathrin-mediated endocytosis and activation of Notch signaling promotes chondrocyte senescence and osteoarthritis development, which is negatively regulated by myosin light chain 3. Myosin light chain 3 (MYL3) protein levels decline sharply in senescent chondrocytes of cartilages from model mice and osteoarthritis (OA) patients. Conditional deletion of Myl3 in chondrocytes significantly promoted, whereas intra-articular injection of adeno-associated virus overexpressing MYL3 delayed, OA progression in male mice. MYL3 deficiency led to enhanced clathrin-mediated endocytosis by promoting the interaction between myosin VI and clathrin, further inducing the internalization of Notch and resulting in activation of Notch signaling in chondrocytes. Pharmacologic blockade of clathrin-mediated endocytosis-Notch signaling prevented MYL3 loss-induced chondrocyte senescence and alleviated OA progression in mice. Our results establish a previously unknown mechanism essential for cellular senescence and provide a potential therapeutic direction for OA.
Project description:Osteoarthritis (OA) is a widespread age-related joint disease caused by the gradual loss of chondrocyte function along with age. Here, we found that UFMylation modification was lower-leveled in senescent cartilage, mediated chondrocyte senescence and OA phenotypes through targeting CAVIN1, which acted as a stimulator in chondrocyte senescence, mainly through promoting CPT1 expression and activating fatty acid β-oxidation (FAO). Physiologically, FAO was at a very low level in chondrocytes, while the anomalous activation of FAO accelerated chondrocyte senescence. UFMylation of CAVIN1 promoted its binding with TRIP12, leading to ubiquitination degradation. Therefore, UFMylation played a pivotal role in post-translationally modification of CAVIN1. Polymeric micellar nanoparticles (NPs) conjugated with UFM1 improved the stability of UFM1 recombinant protein (UFM1-rp), and extended the retention time of UFM1-rp in the mouse joint cavity. The administration of UFM1 into mouse joints using an advanced NP delivery system is effective in attenuating age-related pathogenesis. Therefore, we uncovered a previously unknown mechanism, UFM1-CAVIN1-CPT1 axis, in the protection of OA progression and constructed a new drug for OA treatment, and have provided important preliminary evidence toward the translation of our findings into clinical usage.
Project description:Receptor-interacting protein kinase 1 (RIP1)-mediated necroptosis plays a vital role in various diseases, but the involvement of RIP1 and its functional mechanism in osteoarthritis pathogenesis remains largely unknown. To identify molecular targets of RIP1 in chondrocytes, RNA sequencing was performed in chondrocytes treated with adenovirus expressing RIP1 or vector control. We found that 9857 genes were differentially expressed in chondrocytes after RIP1 overexpression. GO analysis indicated that DNA replication, chromosome segregation and regulation of cell cycle process were upregulated, while terms including cartilage development, skeletal system development, extracellular matrix organization, skeletal system morphogenesis, chondrocyte differentiation, collagen fibril organization and limb development were downregulated. Pathway analysis revealed that IL-17 signaling pathway, cell cycle, DNA replication, proteasome, TNF signaling pathway, cellular senescence and p53 signaling pathway were significantly upregulated by RIP1, meanwhile, ECM-receptor interaction, other glycan degradation and glycosaminoglycan degradation were downregulated. These results underscore the importance of RIP1 in OA by perturbing a series of essential events during disease progression such like cell cycle regulation, chondrocyte differentiation, inflammation and ECM remodeling.