Irisin Attenuates Osteogenic Differentiation of Mouse Mesenchymal Stem Cells via Suppressing Bone Morphogenetic Protein-2 Signaling

Abstract

This study assessed the impact of irisin on mouse mesenchymal stem cells (MSCs) differentiation and the underlying mechanisms. Bone marrow mesenchymal stem cells (BMMSCs) and mesenchymal progenitor cells (KUSA-A1 cells) were isolated from mice and inoculated into petri dishes. Cell proliferation and apoptosis under different concentrations of irisin were detected by MTT. Irisin (1 μM) with nontoxic dose concentration was selected for subsequent experiments. Cells were exposed to 1 μM irisin, osteogenic differentiation was detected by von kossa stain, we employed oil red o stain to test adipocyte differentiation, Alcian blue stain to determine chondrocyte differentiation. BMP-2 expression was analyzed by immunocytochemical staining. Finally, signal transduction pathways and expression and transcription levels of osteogenic differentiation markers in irisin-treated cells were detected by protein imprinting and PCR. BMMSCs and KUSA-A1 cells displayed significantly suppressed osteogenic differentiation and reduced formation of extracellular mineralized matrix, while BMMSCs presented unaffected adipocyte differentiation and chondrocyte differentiation. 1 μM Irisin did not exert cytotoxicity. Further, irisin treatment abated osteogenic differentiation makers Runx2, Osterix, Osteocalcin, Osteopontin, alkaline phosphatase expression. Finally, BMP-2/Smads signaling related molecules (BMP-2, Smad1, Smad4, Smad5 and Smad8) levels were reduced after Irisin treatment. Irisin might inhibit osteoblast differentiation by modulating BMP-2/Smads axis.