title: Adipogenic RNAs are transferred in osteoblasts via bone marrow adipocytes-derived extracellular vesicles (EVs).
abstract: BACKGROUND
  In osteoporosis, bone loss is accompanied by increased marrow adiposity. Given their proximity in the bone marrow and their shared origin, a dialogue between adipocytes and osteoblasts could be a factor in the competition between human Mesenchymal Stem Cells (hMSC) differentiation routes, leading to adipocyte differentiation at the expense of osteoblast differentiation. The adipocyte/osteoblast balance is highly regulated at the level of gene transcription. In our work, we focused on PPARgamma, CEBPalpha and CEBPdelta, as these transcription factors are seen as master regulators of adipogenesis and expressed precociously, and on leptin and adiponectin, considered as adipocyte marker genes. In 2010, our group has demonstrated, thanks to a coculture model, that in the presence of hMSC-derived adipocytes (hMSC-Adi), hMSC-derived osteoblasts (hMSC-Ost) express lesser amounts of osteogenic markers but exhibit the expression of typical adipogenic genes. Nevertheless, the mechanisms underlying this modulation of gene expression are not clarified. Recently, adipocytes were described as releasing extracellular vesicles (EVs), containing and transferring adipocyte specific transcripts, like PPARgamma, leptin and adiponectin. Here, we investigated whether EVs could be the way in which adipocytes transfer adipogenic RNAs in our coculture model.
  
  
  RESULTS
  We observed in hMSC-Ost incubated in hAdi-CM an increase in the adipogenic PPARγ, leptin, CEBPα and CEBPδ transcripts as well as the anti-osteoblastic miR-138, miR30c, miR125a, miR-125b, miR-31 miRNAs, probably implicated in the observed osteocalcin (OC) and osteopontin (OP) expression decrease. Moreover, EVs were isolated from conditioned media collected from cultures of hMSC at different stages of adipocyte differentiation and these specific adipogenic transcripts were detected inside. Finally, thanks to interspecies conditioned media exposition, we could highlight for the first time a horizontal transfer of adipogenic transcripts from medullary adipocytes to osteoblasts.
  
  
  CONCLUSIONS
  Here, we have shown, for the first time, RNA transfer between hMSC-derived adipocytes and osteoblasts through EVs. Additional studies are needed to clarify if this mechanism has a role in the adipocytic switch driven on osteoblasts by adipocytes inside bone marrow and if EVs could be a target component to regulate the competition between osteoblasts and adipocytes in the prevention or in the therapy of osteoporosis and other osteopenia.
authors.affiliation: Univ Lille Nord de France, F-59000, Lille, France. perrine.martin@univ-littoral.fr.|Université du Littoral Côte d'Opale, ULCO, F-62327, Boulogne sur Mer, France. perrine.martin@univ-littoral.fr.|UCEIV EA 4492, F-59140, Dunkerque, France. perrine.martin@univ-littoral.fr.|Université du Littoral Côte d'Opale, EA4492 - Unité de Chimie Environnementale et Interactions sur le Vivant (UCEIV), Maison de la Recherche en Environnement Industriel 2, ULCO, 189A, Avenue Maurice Schumann, 59140, Dunkerque, France. perrine.martin@univ-littoral.fr.
authors.forename: Perrine J
authors.initials: PJ
authors.lastname: Martin
authors.affiliation: Univ Lille Nord de France, F-59000, Lille, France. nathalie.haren@u-picardie.fr.|PMOI EA 4490, IFR 114, F-62327 Boulogne sur Mer and F-59000, Lille, France. nathalie.haren@u-picardie.fr.|Université du Littoral Côte d'Opale, ULCO, F-62327, Boulogne sur Mer, France. nathalie.haren@u-picardie.fr.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Haren
authors.affiliation: Univ Lille Nord de France, F-59000, Lille, France. olfa.ghali@univ-littoral.fr.|PMOI EA 4490, IFR 114, F-62327 Boulogne sur Mer and F-59000, Lille, France. olfa.ghali@univ-littoral.fr.|Université du Littoral Côte d'Opale, ULCO, F-62327, Boulogne sur Mer, France. olfa.ghali@univ-littoral.fr.
authors.forename: Olfa
authors.initials: O
authors.lastname: Ghali
authors.affiliation: Univ Lille Nord de France, F-59000, Lille, France. aline.clabaut@univ-littoral.fr.|PMOI EA 4490, IFR 114, F-62327 Boulogne sur Mer and F-59000, Lille, France. aline.clabaut@univ-littoral.fr.|Université du Littoral Côte d'Opale, ULCO, F-62327, Boulogne sur Mer, France. aline.clabaut@univ-littoral.fr.
authors.forename: Aline
authors.initials: A
authors.lastname: Clabaut
authors.affiliation: Univ Lille Nord de France, F-59000, Lille, France. christophe.chauveau@univ-littoral.fr.|PMOI EA 4490, IFR 114, F-62327 Boulogne sur Mer and F-59000, Lille, France. christophe.chauveau@univ-littoral.fr.|Université du Littoral Côte d'Opale, ULCO, F-62327, Boulogne sur Mer, France. christophe.chauveau@univ-littoral.fr.
authors.forename: Christophe
authors.initials: C
authors.lastname: Chauveau
authors.affiliation: Univ Lille Nord de France, F-59000, Lille, France. pierre.hardouin@univ-littoral.fr.|PMOI EA 4490, IFR 114, F-62327 Boulogne sur Mer and F-59000, Lille, France. pierre.hardouin@univ-littoral.fr.|Université du Littoral Côte d'Opale, ULCO, F-62327, Boulogne sur Mer, France. pierre.hardouin@univ-littoral.fr.
authors.forename: Pierre
authors.initials: P
authors.lastname: Hardouin
authors.affiliation: Univ Lille Nord de France, F-59000, Lille, France. odile.broux@univ-littoral.fr.|PMOI EA 4490, IFR 114, F-62327 Boulogne sur Mer and F-59000, Lille, France. odile.broux@univ-littoral.fr.|Université du Littoral Côte d'Opale, ULCO, F-62327, Boulogne sur Mer, France. odile.broux@univ-littoral.fr.
authors.forename: Odile
authors.initials: O
authors.lastname: Broux
mesh_terms: D017667:Adipocytes / Q000166:cytology*; D050156:Adipogenesis / Q000187:drug effects; D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology*; D051743:CCAAT-Enhancer-Binding Protein-delta / Q000378:metabolism; D022762:CCAAT-Enhancer-Binding Proteins / Q000378:metabolism; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000494:pharmacology; D006801:Humans; D020738:Leptin / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism; D051379:Mice; D035683:MicroRNAs / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism; D015675:Osteocalcin / Q000378:metabolism; D053495:Osteopontin / Q000378:metabolism; D047495:PPAR gamma / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D022142:Secretory Vesicles / Q000378:metabolism*
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; C515848:CEBPA protein, human; C497252:CEBPD protein, human; D017077:Culture Media, Conditioned; D020738:Leptin; D035683:MicroRNAs; D047495:PPAR gamma; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D015675:Osteocalcin; D053495:Osteopontin; D051743:CCAAT-Enhancer-Binding Protein-delta