Insulin-like growth factor 2 (IGF-2) potentiates BMP-9-induced osteogenic differentiation and bone formation.
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.
Chen
Liang
L
Department of Orthopaedic Surgery, Second Affiliated Hospital, Chongqing Medical University, Chongqing, People's Republic of China.
Jiang
Wei
W
Huang
Jiayi
J
He
Bai-Cheng
BC
Zuo
Guo-Wei
GW
Zhang
Wenli
W
Luo
Qing
Q
Shi
Qiong
Q
Zhang
Bing-Qiang
BQ
Wagner
Eric R
ER
Luo
Jinyong
J
Tang
Min
M
Wietholt
Christian
C
Luo
Xiaoji
X
Bi
Yang
Y
Su
Yuxi
Y
Liu
Bo
B
Kim
Stephanie H
SH
He
Connie J
CJ
Hu
Yawen
Y
Shen
Jikun
J
Rastegar
Farbod
F
Huang
Enyi
E
Gao
Yanhong
Y
Gao
Jian-Li
JL
Zhou
Jian-Zhong
JZ
Reid
Russell R
RR
Luu
Hue H
HH
Haydon
Rex C
RC
He
Tong-Chuan
TC
Deng
Zhong-Liang
ZL
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
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