Abstract
Osteoblast lineage-specific differentiation of mesenchymal stem cells is a well regulated but poorly understood process. Both bone morphogenetic proteins (BMPs) and Wnt signaling are implicated in regulating osteoblast differentiation and bone formation. Here we analyzed the expression profiles of mesenchymal stem cells stimulated with Wnt3A and osteogenic BMPs, and we identified connective tissue growth factor (CTGF) as a potential target of Wnt and BMP signaling. We confirmed the microarray results, and we demonstrated that CTGF was up-regulated at the early stage of BMP-9 and Wnt3A stimulations and that Wnt3A-regulated CTGF expression was beta-catenin-dependent. RNA interference-mediated knockdown of CTGF expression significantly diminished BMP-9-induced, but not Wnt3A-induced, osteogenic differentiation, suggesting that Wnt3A may also regulate osteoblast differentiation in a CTGF-independent fashion. However, constitutive expression of CTGF was shown to inhibit both BMP-9- and Wnt3A-induced osteogenic differentiation. Exogenous expression of CTGF was shown to promote cell migration and recruitment of mesenchymal stem cells. Our findings demonstrate that CTGF is up-regulated by Wnt3A and BMP-9 at the early stage of osteogenic differentiation, which may regulate the proliferation and recruitment of osteoprogenitor cells; however, CTGF is down-regulated as the differentiation potential of committed pre-osteoblasts increases, strongly suggesting that tight regulation of CTGF expression may be essential for normal osteoblast differentiation of mesenchymal stem cells.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adenoviridae / genetics
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Alkaline Phosphatase / metabolism
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Animals
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Bone Morphogenetic Proteins / metabolism
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Bone and Bones / physiology
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Cell Differentiation
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Cell Line
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Cell Movement
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Connective Tissue Growth Factor
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Cytoskeletal Proteins / metabolism
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Down-Regulation
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Gene Expression Regulation*
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Green Fluorescent Proteins / metabolism
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Growth Differentiation Factor 2
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Growth Differentiation Factors
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Humans
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Immediate-Early Proteins / biosynthesis*
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Immediate-Early Proteins / genetics*
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Intercellular Signaling Peptides and Proteins / biosynthesis*
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Intercellular Signaling Peptides and Proteins / genetics*
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Intercellular Signaling Peptides and Proteins / metabolism*
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Mesoderm / metabolism*
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Mice
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Mice, Inbred C3H
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Microscopy, Fluorescence
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Models, Biological
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Oligonucleotide Array Sequence Analysis
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Osteoblasts / metabolism*
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Proteins / metabolism
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RNA / chemistry
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RNA / metabolism
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RNA Interference
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Reverse Transcriptase Polymerase Chain Reaction
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Signal Transduction
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Stem Cells
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Time Factors
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Trans-Activators / metabolism
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Up-Regulation
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Wnt Proteins
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Wnt3 Protein
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Wnt3A Protein
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beta Catenin
Substances
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Bone Morphogenetic Proteins
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CCN2 protein, human
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CCN2 protein, mouse
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CTNNB1 protein, human
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CTNNB1 protein, mouse
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Cytoskeletal Proteins
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GDF2 protein, human
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Gdf2 protein, mouse
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Growth Differentiation Factor 2
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Growth Differentiation Factors
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Immediate-Early Proteins
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Intercellular Signaling Peptides and Proteins
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Proteins
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Trans-Activators
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WNT3A protein, human
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Wnt Proteins
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Wnt3 Protein
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Wnt3A Protein
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Wnt3a protein, mouse
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beta Catenin
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Connective Tissue Growth Factor
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Green Fluorescent Proteins
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RNA
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Alkaline Phosphatase