SERINC3 promotes osteogenic differentiation of BMSCs via IL-32/AMPK-mediated autophagy and mitochondrial energy metabolism.

Abstract

Background: SERINC3, a member of the serine incorporator protein family, is known for its roles in viral resistance and tumorigenesis, however, its function in osteogenesis remains unexplored.

Methods: Lentivirus infection, alkaline Phosphatase/Alizarin Red S Staining, and RT-qPCR were used to evaluate the osteogenic differentiation of mesenchymal stem cells mediated by SERINC3. MicroCT, H&E, and Masson staining were performed to investigate the bone formation and bone defect repair via Serinc3 knockout (KO) mice and nude mice. RNA sequencing, Co-IP, Western blotting, and Seahorse energy metabolism analysis were performed to elucidate the regulatory mechanism of SERINC3.

Results: Here, we identify SERINC3 as a critical regulator of osteogenic differentiation of bone marrow-derived stem cells (BMSCs) and bone regeneration. SERINC3 expression was significantly upregulated during osteogenic differentiation of BMSCs and stem cells from human exfoliated deciduous teeth (SHED). Functional assays revealed that SERINC3 overexpression enhanced osteogenic differentiation, proliferation, and migration of MSCs, while Serinc3-KO impaired these processes and led to osteopenia in mice. In a calvarial defect model, Serinc3-KO mice exhibited 42% less bone volume (BV/TV) and 35% lower bone mineral density (BMD), whereas SERINC3-overexpressing BMSCs significantly improved bone repair. Mechanistically, RNA sequencing and pathway analysis revealed that SERINC3 interacts with IL32 to activate the AMPK-ULK1-autophagy axis, thereby promoting osteogenesis. Additionally, SERINC3 enhanced mitochondrial energy metabolism by upregulating tricarboxylic acid cycle enzymes (ACO1, DLAT, SDHA) and increasing oxygen consumption rates. Rescue experiments confirmed that AMPK inhibition or autophagy blockade abolished SERINC3-mediated osteogenic effects, whereas mitochondrial electron transport chain activators restored osteogenesis in SERINC3-knockdown cells.

Conclusions: In summary, this study identifies SERINC3 as a novel regulator of bone formation that orchestrates osteogenesis through IL32-AMPK-autophagy signaling axis and mitochondrial metabolism. These findings highlight SERINC3 as a potential therapeutic target for enhancing bone regeneration and treating skeletal defects.