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 ß-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.