title: Differential signalling through ALK-1 and ALK-5 regulates leptin expression in mesenchymal stem cells.
abstract: Leptin plays a central role in maintaining energy balance, with multiple other systemic effects. Despite leptin importance in peripheral regulation of mesenchymal stem cells (MSC) differentiation, little is known about its expression mechanism. Leptin is often described as adipokine, while it is expressed by other cell types. We have recently shown an in vitro leptin expression, enhanced by glucocorticoids in synovial fibroblasts (SVF). Here, we investigated leptin expression in MSC from bone marrow (BM-MSC) and umbilical cord matrix (UMSC). Results showed that BM-MSC, but not UMSC, expressed leptin that was strongly enhanced by glucocorticoids. Transforming growth factor β1 (TGF-β1) markedly inhibited the endogenous- and glucocorticoid-induced leptin expression in BM-MSC. Since TGF-β1 was shown to signal via ALK-5-Smad2/3 and/or ALK-1-Smad1/5 pathways, we analyzed the expression of proteins from both pathways. In BM-MSC, TGF-β1 increased phosphorylated Smad2 (p-Smad2) expression, while ALK-5 inhibitor (SB431542) induced leptin expression and significantly restored TGF-β1-induced leptin inhibition. In addition, both prednisolone and SB431542 increased p-Smad1/5 expression. These results suggested the ALK-5-Smad2 pathway as an inhibitor of leptin expression, while ALK-1-Smad1/5 as an activator. Indeed, Smad1 expression silencing induced leptin expression inhibition. Furthermore, prednisolone enhanced the expression of TGF-βRII while decreasing p-Smad2 in BM-MSC and SVF but not in UMSC. In vitro differentiation revealed differential osteogenic potential in SVF, BM-MSC, and UMSC that was correlated to their leptin expression potential. Our results suggest that ALK-1/ALK-5 balance regulates leptin expression in MSC. It also underlines UMSC as leptin nonproducer MSC for cell therapy protocols where leptin expression is not suitable.
authors.affiliation: Laboratory of Rheumatology, GIGA-I3, GIGA Research Centre, University and CHU of Liège, Liège, Belgium.
authors.forename: Mustapha
authors.initials: M
authors.lastname: Zeddou
authors.forename: Biserka
authors.initials: B
authors.lastname: Relic
authors.forename: Olivier
authors.initials: O
authors.lastname: Malaise
authors.forename: Edith
authors.initials: E
authors.lastname: Charlier
authors.forename: Aline
authors.initials: A
authors.lastname: Desoroux
authors.forename: Yves
authors.initials: Y
authors.lastname: Beguin
authors.forename: Dominique
authors.initials: D
authors.lastname: de Seny
authors.forename: Michel G
authors.initials: MG
authors.lastname: Malaise
mesh_terms: D030301:Activin Receptors, Type II / Q000235:genetics / Q000378:metabolism*; D001549:Benzamides / Q000494:pharmacology; D001853:Bone Marrow / Q000378:metabolism; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics / Q000378:metabolism; D004149:Dioxoles / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation; D020868:Gene Silencing; D006801:Humans; D020738:Leptin / Q000037:antagonists & inhibitors / Q000378:metabolism*; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D010012:Osteogenesis; D010766:Phosphorylation; D011239:Prednisolone / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; D054411:Receptors, Leptin / Q000037:antagonists & inhibitors / Q000378:metabolism; D018125:Receptors, Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D051899:Smad2 Protein / Q000235:genetics / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology; D014470:Umbilical Cord / Q000166:cytology / Q000378:metabolism
chemical_list: C459179:4-(5-benzo(1,3)dioxol-5-yl-4-pyridin-2-yl-1H-imidazol-2-yl)benzamide; D001549:Benzamides; D050659:Core Binding Factor Alpha 1 Subunit; D004149:Dioxoles; C515448:LEPR protein, human; D020738:Leptin; C493709:RUNX2 protein, human; D054411:Receptors, Leptin; D018125:Receptors, Transforming Growth Factor beta; C497782:SMAD2 protein, human; D051899:Smad2 Protein; D053773:Transforming Growth Factor beta1; D011239:Prednisolone; D017346:Protein Serine-Threonine Kinases; C425364:ACVRL1 protein, human; D030301:Activin Receptors, Type II; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; C000625841:TGFBR1 protein, human
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