title: ADAM12 and alpha9beta1 integrin are instrumental in human myogenic cell differentiation.
abstract: Knowledge on molecular systems involved in myogenic precursor cell (mpc) fusion into myotubes is fragmentary. Previous studies have implicated the a disintegrin and metalloproteinase (ADAM) family in most mammalian cell fusion processes. ADAM12 is likely involved in fusion of murine mpc and human rhabdomyosarcoma cells, but it requires yet unknown molecular partners to launch myogenic cell fusion. ADAM12 was shown able to mediate cell-to-cell attachment through binding alpha9beta1 integrin. We report that normal human mpc express both ADAM12 and alpha9beta1 integrin during their differentiation. Expression of alpha9 parallels that of ADAM12 and culminates at time of fusion. alpha9 and ADAM12 coimmunoprecipitate and participate to mpc adhesion. Inhibition of ADAM12/alpha9beta1 integrin interplay, by either ADAM12 antisense oligonucleotides or blocking antibody to alpha9beta1, inhibited overall mpc fusion by 47-48%, with combination of both strategies increasing inhibition up to 62%. By contrast with blockade of vascular cell adhesion molecule-1/alpha4beta1, which also reduced fusion, exposure to ADAM12 antisense oligonucleotides or anti-alpha9beta1 antibody did not induce detachment of mpc from extracellular matrix, suggesting specific involvement of ADAM12-alpha9beta1 interaction in the fusion process. Evaluation of the fusion rate with regard to the size of myotubes showed that both ADAM12 antisense oligonucleotides and alpha9beta1 blockade inhibited more importantly formation of large (> or =5 nuclei) myotubes than that of small (2-4 nuclei) myotubes. We conclude that both ADAM12 and alpha9beta1 integrin are expressed during postnatal human myogenic differentiation and that their interaction is mainly operative in nascent myotube growth.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale EMI 0011, Faculty of Medicine, Paris XII University, Creteil 94010, France.
authors.forename: Peggy
authors.initials: P
authors.lastname: Lafuste
authors.forename: Corinne
authors.initials: C
authors.lastname: Sonnet
authors.forename: Bénédicte
authors.initials: B
authors.lastname: Chazaud
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Dreyfus
authors.forename: Romain K
authors.initials: RK
authors.lastname: Gherardi
authors.forename: Ulla M
authors.initials: UM
authors.lastname: Wewer
authors.forename: François-Jérôme
authors.initials: FJ
authors.lastname: Authier
mesh_terms: D051722:ADAM Proteins; D000072199:ADAM12 Protein; D019138:Antibodies, Blocking / Q000494:pharmacology; D002448:Cell Adhesion; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D004347:Drug Interactions; D004591:Electrophoresis, Polyacrylamide Gel; D016650:Fluorescein-5-isothiocyanate; D005455:Fluorescent Antibody Technique; D005456:Fluorescent Dyes; D006801:Humans; D015151:Immunoblotting; D007211:Indoles; D016023:Integrins / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008561:Membrane Fusion / Q000187:drug effects; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D018613:Microscopy, Confocal; D024510:Muscle Development; D018485:Muscle Fibers, Skeletal / Q000187:drug effects; D018482:Muscle, Skeletal / Q000196:embryology*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D011233:Precipitin Tests; D011419:Propidium; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012235:Rhodamines
chemical_list: D019138:Antibodies, Blocking; D005456:Fluorescent Dyes; D007211:Indoles; D016023:Integrins; D008565:Membrane Proteins; D016376:Oligonucleotides, Antisense; D012235:Rhodamines; C113256:integrin alpha 9 beta 1; D011419:Propidium; C009434:tetramethylrhodamine isothiocyanate; C007293:DAPI; D051722:ADAM Proteins; D000072199:ADAM12 Protein; C000606480:ADAM12 protein, human; D008666:Metalloendopeptidases; D016650:Fluorescein-5-isothiocyanate