title: Insulin-like growth factor 2 (IGF-2) potentiates BMP-9-induced osteogenic differentiation and bone formation.
abstract: Efficient osteogenic differentiation and bone formation from mesenchymal stem cells (MSCs) should have clinical applications in treating nonunion fracture healing. MSCs are adherent bone marrow stromal cells that can self-renew and differentiate into osteogenic, chondrogenic, adipogenic, and myogenic lineages. We have identified bone morphogenetic protein 9 (BMP-9) as one of the most osteogenic BMPs. Here we investigate the effect of insulin-like growth factor 2 (IGF-2) on BMP-9-induced bone formation. We have found that endogenous IGF-2 expression is low in MSCs. Expression of IGF-2 can potentiate BMP-9-induced early osteogenic marker alkaline phosphatase (ALP) activity and the expression of later markers. IGF-2 has been shown to augment BMP-9-induced ectopic bone formation in the stem cell implantation assay. In perinatal limb explant culture assay, IGF-2 enhances BMP-9-induced endochondral ossification, whereas IGF-2 itself can promote the expansion of the hypertropic chondrocyte zone of the cultured limb explants. Expression of the IGF antagonists IGFBP3 and IGFBP4 leads to inhibition of the IGF-2 effect on BMP-9-induced ALP activity and matrix mineralization. Mechanistically, IGF-2 is further shown to enhance the BMP-9-induced BMPR-Smad reporter activity and Smad1/5/8 nuclear translocation. PI3-kinase (PI3K) inhibitor LY294002 abolishes the IGF-2 potentiation effect on BMP-9-mediated osteogenic signaling and can directly inhibit BMP-9 activity. These results demonstrate that BMP-9 crosstalks with IGF-2 through PI3K/AKT signaling pathway during osteogenic differentiation of MSCs. Taken together, our findings suggest that a combination of BMP-9 and IGF-2 may be explored as an effective bone-regeneration agent to treat large segmental bony defects, nonunion fracture, and/or osteoporotic fracture.
authors.affiliation: Department of Orthopaedic Surgery, Second Affiliated Hospital, Chongqing Medical University, Chongqing, People's Republic of China.
authors.forename: Liang
authors.initials: L
authors.lastname: Chen
authors.forename: Wei
authors.initials: W
authors.lastname: Jiang
authors.forename: Jiayi
authors.initials: J
authors.lastname: Huang
authors.forename: Bai-Cheng
authors.initials: BC
authors.lastname: He
authors.forename: Guo-Wei
authors.initials: GW
authors.lastname: Zuo
authors.forename: Wenli
authors.initials: W
authors.lastname: Zhang
authors.forename: Qing
authors.initials: Q
authors.lastname: Luo
authors.forename: Qiong
authors.initials: Q
authors.lastname: Shi
authors.forename: Bing-Qiang
authors.initials: BQ
authors.lastname: Zhang
authors.forename: Eric R
authors.initials: ER
authors.lastname: Wagner
authors.forename: Jinyong
authors.initials: J
authors.lastname: Luo
authors.forename: Min
authors.initials: M
authors.lastname: Tang
authors.forename: Christian
authors.initials: C
authors.lastname: Wietholt
authors.forename: Xiaoji
authors.initials: X
authors.lastname: Luo
authors.forename: Yang
authors.initials: Y
authors.lastname: Bi
authors.forename: Yuxi
authors.initials: Y
authors.lastname: Su
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.forename: Stephanie H
authors.initials: SH
authors.lastname: Kim
authors.forename: Connie J
authors.initials: CJ
authors.lastname: He
authors.forename: Yawen
authors.initials: Y
authors.lastname: Hu
authors.forename: Jikun
authors.initials: J
authors.lastname: Shen
authors.forename: Farbod
authors.initials: F
authors.lastname: Rastegar
authors.forename: Enyi
authors.initials: E
authors.lastname: Huang
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Gao
authors.forename: Jian-Li
authors.initials: JL
authors.lastname: Gao
authors.forename: Jian-Zhong
authors.initials: JZ
authors.lastname: Zhou
authors.forename: Russell R
authors.initials: RR
authors.lastname: Reid
authors.forename: Hue H
authors.initials: HH
authors.lastname: Luu
authors.forename: Rex C
authors.initials: RC
authors.lastname: Haydon
authors.forename: Tong-Chuan
authors.initials: TC
authors.lastname: He
authors.forename: Zhong-Liang
authors.initials: ZL
authors.lastname: Deng
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001857:Bone Matrix / Q000187:drug effects / Q000378:metabolism; D002113:Calcification, Physiologic / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D019902:Chondrocytes / Q000187:drug effects / Q000473:pathology; D005333:Fetus; D055427:Growth Differentiation Factor 2 / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D006984:Hypertrophy; D020007:Implants, Experimental; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000378:metabolism; D018974:Insulin-Like Growth Factor Binding Protein 4 / Q000378:metabolism; D007335:Insulin-Like Growth Factor II / Q000378:metabolism* / Q000494:pharmacology; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology; D051379:Mice; D010012:Osteogenesis / Q000187:drug effects; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D051785:Smad Proteins / Q000378:metabolism
chemical_list: D015415:Biomarkers; D055427:Growth Differentiation Factor 2; D018972:Insulin-Like Growth Factor Binding Protein 3; D018974:Insulin-Like Growth Factor Binding Protein 4; D051785:Smad Proteins; D007335:Insulin-Like Growth Factor II; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D000469:Alkaline Phosphatase