The effects of myostatin on adipogenic differentiation of human bone marrow-derived mesenchymal stem cells are mediated through cross-communication between Smad3 and Wnt/beta-catenin signaling pathways.
The effects of myostatin on adipogenic differentiation are poorly understood, and the underlying mechanisms are unknown. We determined the effects of human recombinant myostatin protein on adipogenesis of bone marrow-derived human mesenchymal stem cells (hMSCs) and adipose tissue-derived preadipocytes. For both progenitor cell types, differentiation in the presence of myostatin caused a dose-dependent reduction of lipid accumulation and diminished incorporation of exogenous fatty acid into cellular lipids. Myostatin significantly down-regulated the expression of adipocyte markers PPARgamma, C/EBPalpha, leptin, and aP2, but not C/EBPbeta. Overexpression of PPARgamma, but not C/EBPbeta, blocked the inhibitory effects of myostatin on adipogenesis. Myostatin induced phosphorylation of Smad3 in hMSCs; knockdown of Smad3 by RNAi or inhibition of its upstream kinase by an Alk5 inhibitor blocked the inhibitory effect of myostatin on adipogenesis in hMSCs, implying an important role of Smad3 activation in this event. Furthermore, myostatin enhanced nuclear translocation of beta-catenin and formation of the Smad3-beta-catenin-TCF4 complex, together with the altered expression of a number of Wnt/beta-catenin pathway genes in hMSCs. The inhibitory effects of myostatin on adipogenesis were blocked by RNAi silencing of beta-catenin and diminished by overexpression of dominant-negative TCF4. The conclusion is that myostatin inhibited adipogenesis in human bone marrow-derived mesenchymal stem cells and preadipocytes. These effects were mediated, in part, by activation of Smad3 and cross-communication of the TGFbeta/Smad signal to Wnt/beta-catenin/TCF4 pathway, leading to down-regulation of PPARgamma.
Guo
Wen
W
Section of Endocrinology, Diabetes, and Nutrition, Boston University School of Medicine, Boston Medical Center, 670 Albany Street, Boston, MA 02118, USA. wguo@bu.edu
Flanagan
John
J
Jasuja
Ravi
R
Kirkland
James
J
Jiang
Lan
L
Bhasin
Shalender
S
D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000502:physiology; D017667:Adipocytes / Q000166:cytology / Q000378:metabolism*; D050156:Adipogenesis / Q000187:drug effects / Q000502:physiology*; D000328:Adult; D000943:Antigens, Differentiation / Q000096:biosynthesis / Q000235:genetics; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism*; D002467:Cell Nucleus; D002478:Cells, Cultured; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D055435:Myostatin; D047495:PPAR gamma / Q000096:biosynthesis / Q000235:genetics; D010766:Phosphorylation / Q000187:drug effects; D034622:RNA Interference; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D051900:Smad3 Protein / Q000235:genetics / Q000378:metabolism*; D051820:TCF Transcription Factors / Q000235:genetics / Q000378:metabolism; D058118:Transcription Factor 7-Like 2 Protein; D016212:Transforming Growth Factor beta / Q000378:metabolism / Q000494:pharmacology*; D051153:Wnt Proteins / Q000235:genetics / Q000378:metabolism*; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*
D000943:Antigens, Differentiation; C525911:MSTN protein, human; D055435:Myostatin; D047495:PPAR gamma; C497790:SMAD3 protein, human; D051900:Smad3 Protein; D051820:TCF Transcription Factors; C544894:TCF7L2 protein, human; D058118:Transcription Factor 7-Like 2 Protein; D016212:Transforming Growth Factor beta; D051153:Wnt Proteins; D051176:beta Catenin