In vitro development of precursor cells in the myogenic lineage☆

[摘要] Expressionofthemuscle-specificintegralmembraneproteinH36andtheintermediatefilamentproteindesmin,detectedbyimmunofluorescence,wasusedtoidentifycellsatdistinctstagesintheskeletalmyogeniclineage.Theseproteinswerecoordinatelyexpressedinculturesofrathindlimbmyoblastsfrom17-and19-dayfetusesandnewbornpups,andinsatellitecellsfromjuveniles.BothH36+anddesmin+cellswerepresentinculturesfrom13.5-and15-dayembryonichindlimbs,butdesminexpressionwasmoreprevalent:H36−/desmin+myoblastspredominateduringthisearlystageofdevelopment.H36wasnotdetectedinDay12embryohindlimbbudcellsinvivonorinculturessoonafterplating.Initially,only1%oftheDay12limbbudcellsexpresseddesmin.Whenthesecellswereseriallypassagedevery3–4days,cellswithallthreepossiblemyogenicphenotypesdeveloped:thatis,H36+/desmin−,H36+/desmin+,andH36−/desmin+cells.TherewasaprogressiveincreaseinthefrequencyofH36+cells,with75%ofcellspositivebypassage6(Day27invitro).Themaximumfrequencyofcellsthatexpresseddesminoccurredinpassage5(Day23invitro).TheseresultsdemonstratethatprecursorstothecellsthatexpressH36anddesminarepresentinthe12-dayembryohindlimbbudandthatthetransitionfromH36−/desmin−precursorstocellswithamyogenicphenotypecanoccurinvitro.MyoD1andmyogeninwerenotdetectedinthesecells,suggestingthattheinitialexpressionofH36anddesmininthemyogeniclineagemayprecedeand/orisindependentoftheseregulatoryproteins.Theconversionofprecursorcellsinthe12-daylimbbudtoamoreadvancedstageofdevelopmentservestodefineadditionalcellsinthemyogeniclineage.Theabilitytomonitorinvitrothesestagesofdevelopmentaffordstheopportunitytostudyhowtheyareregulated.

[学科分类] 生物科学（综合）