AMPK promotes osteogenesis and inhibits adipogenesis through AMPK-Gfi1-OPN axis.
Several metabolic, genetic and oncogenic bone diseases share the common pathological phenotype of defective bone marrow stromal cell (BMSC) differentiation. Many reports in bone science in the past several years have suggested that the skeleton also has an endocrine role. The role of AMP-activated protein kinase (AMPK) as an energy metabolism sensor and how it regulates BMSC differentiation is largely unknown. In the current study, we used AMPK agonists to activate AMPK in MC3T3-E1 cells to investigate the functional roles of AMPK in osteogenesis. However, metformin and AICAR failed to activate AMPK consistently. Therefore, we established MC3T3-E1 and 3T3-L1 cell models of AMPK α subunit overexpression through lentivirus vector, in which AMPK was overactivated. AMPK hyperactivation stimulated MC3T3-E1 cell osteogenesis and inhibited 3T3-L1 cell adipogenesis. Osteopontin (OPN) mediated AMPK regulation of osteogenesis and adipogenesis. Furthermore, we provided evidence that the transcriptional repressor growth factor independence-1 (Gfi1) was downregulated and disassociated from the OPN promoter in response to AMPK activation, resulting in the upregulation of OPN. Overexpression of wild-type and dominant-negative Gfi1 modulated MC3T3-E1 osteogenesis and 3T3-L1 adipogenesis. Further evidence suggested that AMPK enhanced ectopic bone formation of MC3T3-E1 cells through the AMPK-Gfi1-OPN axis. In conclusion, AMPK was sufficient to stimulate osteogenesis of MC3T3-E1 cells and inhibit adipogenesis of 3T3-L1 cells through the AMPK-Gfi1-OPN axis. These findings helped elucidate the molecular mechanisms underlying AMPK regulation of osteogenesis and adipogenesis.
Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhizaoju Road, Shanghai 200011, People's Republic of China.
Yu-Gang
YG
Wang
Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhizaoju Road, Shanghai 200011, People's Republic of China.
Xin-Hua
XH
Qu
Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhizaoju Road, Shanghai 200011, People's Republic of China.
Ying
Y
Yang
Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhizaoju Road, Shanghai 200011, People's Republic of China.
Xiu-Guo
XG
Han
Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhizaoju Road, Shanghai 200011, People's Republic of China.
Lei
L
Wang
Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhizaoju Road, Shanghai 200011, People's Republic of China.
Han
H
Qiao
Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhizaoju Road, Shanghai 200011, People's Republic of China. Electronic address: chillow@163.com.
Qi-Ming
QM
Fan
Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhizaoju Road, Shanghai 200011, People's Republic of China. Electronic address: tingtingtang@hotmail.com.
Ting-Ting
TT
Tang
Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, 639 Zhizaoju Road, Shanghai 200011, People's Republic of China; The Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai JiaoTong University School of Medicine (SJTUSM) & Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS), Shanghai 200025, China. Electronic address: krdai@163.com.
Ke-Rong
KR
Dai
D041721:3T3-L1 Cells; D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D050156:Adipogenesis / Q000187:drug effects; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001842:Bone and Bones / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D008687:Metformin / Q000494:pharmacology; D051379:Mice; D008819:Mice, Nude; D010012:Osteogenesis / Q000187:drug effects; D053495:Osteopontin / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012265:Ribonucleotides / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D014157:Transcription Factors / Q000378:metabolism*
D015415:Biomarkers; D004268:DNA-Binding Proteins; C079873:Gfi1 protein, mouse; D012265:Ribonucleotides; D014157:Transcription Factors; D053495:Osteopontin; D000620:Aminoimidazole Carboxamide; D008687:Metformin; D055372:AMP-Activated Protein Kinases; C031143:AICA ribonucleotide
AMP-activated protein kinase; Adipogenesis; Growth factor independence-1; Osteogenesis; Osteopontin