title: Differential expression of the IL-1 system components during in vitro myogenesis: implication of IL-1beta in induction of myogenic cell apoptosis.
abstract: We evaluated the expression of IL-1 system by normal human myogenic cells during in vitro myogenesis and the effect of exogenous IL-1beta. Expression of IL-1alpha and beta, IL-1 receptor antagonist (IL-1Ra), IL-1RI and II, IL-1R accessory protein (IL-1RAcP) and IL-1beta converting enzyme (ICE) was studied by immunocytochemistry, immunoblotting, ELISA and RT - PCR. Cell proliferation was evaluated by [3H]thymidine incorporation, cell fusion by flow cytometry and cell death by in situ end-labelling. Human normal myogenic cells constitutively produced IL-1beta and ICE, with a maximum expression at time of cell fusion. IL-1Rs and IL-1RAcP expression reached a peak at time of commitment to fusion. Myogenic cells produced small amounts of IL-1Ra at latest stages of culture, and only the intracellular isoform. Exposure of cultures to exogenous IL-1beta (1-5 ng/ml) induced myogenic cell apoptosis, without effect on cell proliferation or fusion. IL-1beta-induced cell death was associated with morphological changes including spreading appearance of cells and alteration of cell alignment. We conclude that (1) human myogenic cells constitutively produce IL-1beta; (2) IL-1 system components are differentially expressed during in vitro myogenesis; (3) IL-1 system participates to the coordinated regulation of cell density during normal myogenesis, which could serve to control the muscle mass in vivo.
authors.affiliation: Groupe d'Etudes et de Recherche sur le Muscle et le Nerf (GERMEN), Faculté de Médecine de Créteil-Université Paris, XII Val-de-Marne, Créteil, France. authier@univ-paris12.fr
authors.forename: F J
authors.initials: FJ
authors.lastname: Authier
authors.forename: B
authors.initials: B
authors.lastname: Chazaud
authors.forename: A
authors.initials: A
authors.lastname: Plonquet
authors.forename: M C
authors.initials: MC
authors.lastname: Eliezer-Vanerot
authors.forename: F
authors.initials: F
authors.lastname: Poron
authors.forename: L
authors.initials: L
authors.lastname: Belec
authors.forename: G
authors.initials: G
authors.lastname: Barlovatz-Meimon
authors.forename: R K
authors.initials: RK
authors.lastname: Gherardi
mesh_terms: D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology*; D053179:Caspase 7; D020169:Caspases; D018929:Cell Culture Techniques; D003546:Cysteine Endopeptidases; D006801:Humans; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1 / Q000037:antagonists & inhibitors* / Q000096:biosynthesis* / Q000494:pharmacology*; D053577:Interleukin-1 Receptor Accessory Protein; D018485:Muscle Fibers, Skeletal / Q000166:cytology*; D014176:Protein Biosynthesis; D011506:Proteins; D012795:Sialoglycoproteins / Q000096:biosynthesis / Q000494:pharmacology
chemical_list: C507765:IL1RAP protein, human; C507763:IL1RN protein, human; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1; D053577:Interleukin-1 Receptor Accessory Protein; D011506:Proteins; D012795:Sialoglycoproteins; C505520:CASP7 protein, human; D053179:Caspase 7; D020169:Caspases; D003546:Cysteine Endopeptidases