Rationale: Osteoarthritis (OA) is the most common joint disease worldwide. Previous studies have identified the imbalance between extracellular matrix (ECM) catabolism and anabolism in cartilage tissue as the main cause. To date, there is no cure for OA despite a few symptomatic treatments. This study aimed to investigate the role of CircCDK14, a novel circRNA factor, in the progression of OA, and to elucidate its underlying molecular mechanisms.

Postmenopausal osteoporosis (PMOP) is a chronic systemic bone metabolism disorder. Promotion in the patterns of human bone marrow mesenchymal stem cells (hBMSCs) differentiation towards osteoblasts contributes to alleviating osteoporosis. Aucubin, a natural compound isolated from the well‐known herbal medicine Eucommia, was previously shown to possess various pharmacological effects. However, its effects on hBMSCs of PMOP patients are unknown. The aim of this present research was to investigate the impact and underlying process of aucubin on cell proliferation and osteogenic differentiation in hBMSCs isolated from PMOP patients. The ability of aucubin to inhibit the ferroptosis induced by erastin in hBMSCs was detected; ROS production, ferrous ion levels, SOD, MDA, and GPX activities were tested by using commercial kits. Next, ALP staining, ARS staining, RT‐qPCR, RNA‐sequencing, and Western blot were applied for determining the mRNA and protein expression levels associated with the osteogenesis of hBMSCs. The study also explored the involvement of BMP2/Smads signalling in aucubin promoting the osteogenesis of hBMSCs and evaluated the effects of aucubin intervention on osteoporosis using an ovariectomised rat model. The results indicated that aucubin significantly inhibited ROS generation and oxidative stress induced by erastin and protected against ferroptosis in hBMSCs. Additionally, aucubin facilitated osteogenic differentiation of hBMSCs by activating the BMP2/SMADs pathway and attenuated the progression of osteoporosis in OVX rats, suggesting a potential therapeutic benefit for postmenopausal osteoporosis (PMOP).

Background: Osteoarthritis (OA) is the most prevalent age-related disease in the world. Chondrocytes undergo an age-dependent decline in their proliferation and synthetic capacity, which is the main cause of OA development. However, the intrinsic mechanism of chondrocyte senescence is still unclear. This study aimed to investigate the role of a novel long non-coding RNA (lncRNA), AC006064.4–201 in the regulation of chondrocyte senescence and OA progression and to elucidate the underlying molecular mechanisms. Methods: The function of AC006064.4–201 in chondrocytes was assessed using western blotting, quantitative real-time polymerase chain reaction (qRT-PCR), immunofluorescence (IF) and β-galactosidase staining. The interaction between AC006064.4–201 and polypyrimidine tract-binding protein 1 (PTBP1), as well as cyclin-dependent kinase inhibitor 1B (CDKN1B), was evaluated using RPD-MS, fluorescence in situ hybridization (FISH), RNA immunoprecipitation (RIP) and RNA pull-down assays. Mice models were used to investigate the role of AC006064.4–201 in post-traumatic and age-related OA in vivo. Results: Our research revealed that AC006064.4–201 was downregulated in senescent and degenerated human cartilage, which could alleviate senescence and regulate metabolism in chondrocytes. Mechanically, AC006064.4–201 directly interacts with PTBP1 and blocks the binding between PTBP1 and CDKN1B mRNA, thereby destabilizing CDKN1B mRNA and decreasing the translation of CDKN1B. The in vivo experiments were consistent with the results of the in vitro experiments. Conclusions: The AC006064.4–201/PTBP1/CDKN1B axis plays an important role in OA development and provides new molecular markers for the early diagnosis and treatment of OA in the future. Graphical Schematic diagram of AC006064.4–201 mechanism. A schematic diagram of the mechanism underlying the effect of AC006064.4–201

Osteoarthritis (OA) is a whole-joint disorder that interferes with the quality of life in older individuals. Here we report that ZDHHC11 is highly expressed in articular chondrocytes but is downregulated in the degenerated cartilage of aged mice and patients with OA. ZDHHC11 prevents chondrocyte senescence and promotes cartilage anabolism, culminating in an improved OA phenotype. The deletion of Zdhhc11 in mice (Zdhhc11^fl/fl) exacerbates OA progression in a destabilized medial meniscus model. Specifically, we identify ZDHHC11 as a key palmitoyltransferase whose depletion leads to a GNB2-dependent E3 ubiquitin ligase-mediated proteasomal degradation of APOD. Mechanistically, ZDHHC11-mediated palmitoylation alleviates OA progression by deactivating the GATA4–P65 signaling pathway. We also propose an original lipid nanoparticle-based platform for Zdhhc11 mRNA delivery to rejuvenate impaired cartilage by specifically targeting chondrocytes in vivo. Collectively, ZDHHC11-dependent palmitoylation is essential for ameliorating OA, and the targeted delivery of ZDHHC11 may serve as a promising strategy for future OA treatment.

Introduction: Osteosarcoma is the most common primary malignancy of the bone among adolescents and children. Despite intensive chemotherapy and aggressive surgery, the 5-year survival rate of osteosarcoma still falls under 70%, mainly due to its tendency to metastasize and to develop drug resistance. Therefore, new treatments for osteosarcoma are urgently needed. HGF/c-Met signaling pathway, when dysregulated, is involved in the onset, progression and metastasis of various cancers, making the HGF/c-Met axis a promising therapeutic target. Methods: In this study, we found Met to be a cancer-promoting gene in osteosarcoma as well, and aimed to investigate the role of a c-met inhibitor (PHA-665752) in osteosarcoma. For this purpose, two human osteosarcoma cell lines (143B and U2OS) were introduced in this study and treated with PHA-665752. CCK8 cell proliferation assay was performed to obtain the IC₅₀ value of PHA-665752 for 143B and U2OS. After that, colony formation assay, transwell migration and invasion assay and wound-healing assay were performed. Furthermore, a tumor-transplanted mouse model was used for in vivo experiments. Results: Our results showed that PHA-665752 could suppress osteosarcoma progression, promote apoptosis and inhibit proliferation of human osteosarcoma cells. Moreover, we found ERK1/2 pathway to be an important mediator underlying the osteosarcoma-suppressing function of PHA-665752. LY3214996, a highly selective inhibitor of the ERK1/2 pathway, was able to antagonize the effects of PHA-665752 in osteosarcoma. Finally, in vivo experiments indicated that PHA-665752 suppressed tumor growth in a tumor-transplanted mouse model. Conclusion: Taken together, Met provided a druggable target for osteosarcoma and PHA-665752 is a promising candidate for anti-osteosarcoma treatments.