title: Inhibition of de novo ceramide synthesis upregulates phospholipase D and enhances myogenic differentiation.
abstract: In L6 skeletal myoblasts induced to differentiate by Arg8-vasopressin treatment, a short-lived lowering of ceramide levels was observed, followed by a long-lasting elevation that was prevented by inhibitors of the de novo synthesis pathway, fumonisin B1 and myriocin. Both inhibitors increased the expression of myogenic differentiation markers and cell fusion rate, whereas short-chain ceramides inhibited these responses. Similar drug effects were observed on primary mouse satellite cell differentiation. Furthermore, bacterial sphingomyelinase overexpression suppressed myogenin nuclear accumulation in L6 cells. These data suggested that endogenous ceramide mediates a negative feedback mechanism limiting myogenic differentiation, and that inhibitors of ceramide synthesis promoted myogenesis by removing this control. Phospholipase D (PLD), a recognized target of ceramide, is required for myogenesis, as shown by the negative effects of PLD1 isoform depletion obtained by siRNA treatment. Fumonisin induced an increase in PLD activity of L6 cells, whereas C6-ceramide decreased it. The expression of PLD1 mRNA transcripts was selectively decreased by C6-ceramide, and increased by ceramide synthesis inhibitors. An early step of myogenic response is the PLD1-dependent formation of actin stress fiber-like structures. C6-ceramide addition or overexpression of sphingomyelinase impaired actin fiber formation. Ceramide might thus regulate myogenesis through downregulation of PLD1 expression and activity.
authors.affiliation: INSERM, Unit 585, Villeurbanne, F-69621 France.
authors.forename: Saïda
authors.initials: S
authors.lastname: Mebarek
authors.forename: Hiba
authors.initials: H
authors.lastname: Komati
authors.forename: Fabio
authors.initials: F
authors.lastname: Naro
authors.forename: Caroline
authors.initials: C
authors.lastname: Zeiller
authors.forename: Monica
authors.initials: M
authors.lastname: Alvisi
authors.forename: Michel
authors.initials: M
authors.lastname: Lagarde
authors.forename: Annie-France
authors.initials: AF
authors.lastname: Prigent
authors.forename: Georges
authors.initials: G
authors.lastname: Némoz
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D002518:Ceramides / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000502:physiology; D002999:Clone Cells; D018482:Muscle, Skeletal / Q000378:metabolism*; D010739:Phospholipase D / Q000378:metabolism / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D015854:Up-Regulation
chemical_list: D002518:Ceramides; D012333:RNA, Messenger; D010739:Phospholipase D