Insulin receptor substrate 1 regulates the cellular differentiation and the matrix metallopeptidase expression of preosteoblastic cells.
Insulin receptor substrate 1 (IRS1) is an essential molecule for the intracellular signaling of IGF1 and insulin, which are potent anabolic regulators of bone metabolism. Osteoblastic IRS1 is essential for maintaining bone turnover; however, the mechanism underlying this regulation remains unclear. To clarify the role of IRS1 in bone metabolism, we employed RNA interference to inhibit IRS1 gene expression and observed the effects of silencing this gene on the proliferation and differentiation of and the expression of matrix metallopeptidase (MMP) and tumor necrosis factor receptor superfamily, member 11b (TNFRSF11B) in MC3T3-E1 cells. Our results showed that IRS1 short hairpin RNAs can effectively suppress the expression of IRS1, and inhibit the phosphorylation of AKT in IRS1 pathway; reduce the expression of MMP2, MMP3, MMP13, and MMP14, decrease the expression of TNFRSF11B and RANKL (also known as tumor necrosis factor (ligand) superfamily, member 11), however increase the RANKL/TNFRSF11B ratio; decrease cell survival, proliferation, and mineralization, and impair the differentiation of MC3T3-E1 cells. The downregulation of IRS1 had no effect on the expression of MMP1. Our findings suggest that IRS1 not only promotes bone formation and mineralization but also might play roles in bone resorption partly via the regulation of MMPs and RANKL/TNFRSF11B ratio, thus regulates the bone turnover.
Bu
Yan-Hong
YH
Institute of Metabolism and Endocrinology, Department of Clinical Laboratory, The Second Xiang-Ya Hospital of Central South University, 410011 ChangSha, People's Republic of China.
He
Yu-Ling
YL
Zhou
Hou-De
HD
Liu
Wei
W
Peng
Dan
D
Tang
Ai-Guo
AG
Tang
Ling-Li
LL
Xie
Hui
H
Huang
Qiu-Xia
QX
Luo
Xiang-Hang
XH
Liao
Er-Yuan
EY
D000704:Analysis of Variance; D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation / Q000502:physiology*; D002460:Cell Line; D049109:Cell Proliferation; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D005434:Flow Cytometry; D015870:Gene Expression; D055504:Insulin Receptor Substrate Proteins / Q000235:genetics / Q000378:metabolism*; D020782:Matrix Metalloproteinases / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D010006:Osteoblasts / Q000378:metabolism*; D053244:Osteoprotegerin / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000502:physiology; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D053245:RANK Ligand / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction
D055504:Insulin Receptor Substrate Proteins; D053244:Osteoprotegerin; D053245:RANK Ligand; D051057:Proto-Oncogene Proteins c-akt; D020782:Matrix Metalloproteinases