N6-methyladenosine(m6A)is the most abundant posttranscriptional methylation modification that occurs in mRNA and modulates the fine-tuning of various biological processes in mammalian development and human diseases.In this study we investigated the role of m6A modification in the osteogenesis of mesenchymal stem cells(MSCs),and the possible mechanisms by which m6A modification regulated the processes of osteoporosis and bone necrosis.We performed systematic analysis of the differential gene signatures in patients with osteoporosis and bone necrosis and conducted m6A-RNA immunoprecipitation(m6A-RIP)sequencing to identify the potential regulatory genes involved in osteogenesis.We showed that fat mass and obesity(FTO),a primary m6A demethylase,was significantly downregulated in patients with osteoporosis and osteonecrosis.During the differentiation of human MSCs into osteoblasts,FTO was markedly upregulated.Both depletion of FTO and application of the FTO inhibitor FB23 or FB23-2 impaired osteogenic differentiation of human MSCs.Knockout of FTO in mice resulted in decreased bone mineral density and impaired bone formation.PPARG,a biomarker for osteoporosis,was identified as a critical downstream target of FTO.We further revealed that FTO mediated m6A demethylation in the 3'UTR of PPARG mRNA,and reduced PPARG mRNA stability in an YTHDF1-dependent manner.Overexpression of PPARG alleviated FTO-mediated osteogenic differentiation of MSCs,whereas knockdown of PPARG promoted FTO-induced expression of the osteoblast biomarkers ALPL and OPN during osteogenic differentiation.Taken together,this study demonstrates the functional significance of the FTO-PPARG axis in promoting the osteogenesis of human MSCs and sheds light on the role of m6A modification in mediating osteoporosis and osteonecrosis.

Liu-shan Chen;Meng Zhang;Peng Chen;Xiao-feng Xiong;Pei-qing Liu;Hai-bin Wang;Jun-jian Wang;Juan Shen

Guangdong Provincial Key Laboratory of Pharmaceutical Bioactive Substances,Guangdong Pharmaceutical University,Guangzhou 510006,China;Department of Orthopedics,Henan Provincial People's Hospital,People's Hospital of Zhengzhou University,People's Hospital of Henan University,Zhengzhou 450003,China;The First Clinical Medical College,Guangzhou University of Chinese Medicine,Guangzhou 510405,China;Department of Laboratory of New Drug Design and Evaluation,School of Pharmaceutical Sciences,Sun Yat-Sen University,Guangzhou 510006,China

中国药理学报（英文版）

[1]Liu-shan Chen;Meng Zhang;Peng Chen;Xiao-feng Xiong;Pei-qing Liu;Hai-bin Wang;Jun-jian Wang;Juan Shen-.The m6A demethylase FTO promotes the osteogenesis of mesenchymal stem cells by downregulating PPARG)[J].中国药理学报（英文版）,2022(05):1311-1323

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