The UFM1 System Alleviated Fatty Acid Oxidation and Chondrocyte Senescence via the UFMylation of CAVIN1. The UFM1 System Alleviated Fatty Acid Oxidation and Chondrocyte Senescence via the UFMylation of CAVIN1

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. Overall design: Cartilage was obtained from 3 knee replacement patients, and the extracted chondrocytes were divided into two groups, one as a control group and the other as a CAVIN1 knockout group, with 3 biological replicates per group.