Fig 2: Irisin-mediated SIRT1 inhibited FTO expression via RANBP2-mediated SUMOylation.A RANBP2 protein expression in Sirt1 knockdown cells with or without irisin treatment was assayed by western blotting. B Co-immunoprecipitation of SIRT1 with RANBP2 in BMMSCs with or without irisin treatment. C Colocalization of SIRT1 and RANBP2 after treatment with or without irisin in BMMSCs was exhibited in confocal immunofluorescent images. D Representative images of Oil red O staining in Sirt1-overexpressed cells with or without Ranbp2 knockdown, and quantitative analysis of Oil red O staining. E mRNA expressions of Pparγ, C/ebpα, and C/ebpβ in Sirt1-overexpressed cells with or without Ranbp2 knockdown. F Fto mRNA expression in Sirt1-overexpressed cells with or without Ranbp2 knockdown was assayed by qRT-PCR. G FTO protein expression in Sirt1-overexpressed cells with or without Ranbp2 knockdown was assayed by western blotting. H Co-immunoprecipitation was used to detect the interactions of FTO with SIRT1 and RANBP2 proteins in irisin-treated or non-treated BMMSCs. Co-immunoprecipitation was used to detect the interactions of FTO with SUMO2/3 in irisin-treated or non-treated BMMSCs. The values are mean ± SD of at least three independent experiments; n.s.p > 0.05, *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001.

Fig 3: Irisin-mediated SIRT1 destabilizes FTO through the deacetylation of RANBP2, thereby inhibiting the adipogenic differentiation of bone marrow mesenchymal stem cells (BMMSCs), suggesting that the irisin/SIRT1/RANBP2/FTO signaling axis may serve as a new target for therapeutic drugs in OP.