Skeletal muscle satellite cell diversity: Satellite cells form fibers of different types in cell culture☆

摘要

Followingskeletalmuscleinjury,newfibersformfromresidentsatellitecellswhichreestablishthefibercompositionoftheoriginalmuscle.Wehaveusedacellculturesystemtoanalyzesatellitecellsisolatedfromadultchickenandquailpectoralismajor(PM;afastmuscle)andanteriorlatissimusdorsi(ALD;aslowmuscle)todetermineifsatellitecellsisolatedfromfastorslowmusclesproduceoneorseveraltypesoffiberswhentheyformnewfibersinvitrointheabsenceofinnervationoraspecificextracellularmilieu.Thetypesoffibersformedinsatellitecellculturesweredeterminedusingimmunoblottingandimmunocytochemistrywithmonoclonalantibodiesspecificforavianfastandslowmyosinheavychain(MHC)isoforms.Wefoundthatsatellitecellswereofdifferenttypesandthatfastandslowmusclesdifferedinthepercentageofeachtypetheycontained.PrimarysatellitecellsisolatedfromthePMformedonlyfastfibers,whileupto25%ofthoseisolatedfromALDformedfibersthatwerebothfastandslow(fast/slowfibers),theremainderbeingfastonly.Fast/slowfibersformedfromchickensatellitecellsexpressedslowMHC1,whileslowMHC2predominatedinfast/slowfibersformedfromquailsatellitecells.Prolongedprimaryculturedidnotaltertherelativeproportionsoffasttofast/slowfibersinhighdensityculturesofeitherchickenorquailsatellitecells.Nochangeincommitmentwasobservedinfibersformedfromchickensatellitecellprogenyrepeatedlysubculturedathighdensity,whilefibersformedfromsubculturedquailsatellitecellprogenydemonstratedincreasingcommitmenttofast/slowfibertypeformation.Quailsatellitecellsclonedfromhighdensityculturesformedcoloniesthatdemonstratedasimilarchangeincommitmentfromfasttofast/slow,asdidseriallysubclonedindividualsatellitecellprogeny,indicatingthattheobservedchangefromfasttofast/slowdifferentiationresultedfromintrinsicchangeswithinasatellitecell.Thussatellitecellsfreshlyisolatedfromadultchickenandquailarecommittedtoformfibersofatleasttwotypes,satellitecellsofthesetwotypesarefoundindifferentproportionsinfastandslowmuscles,andrepeatedcellproliferationofquailsatellitecellprogenymayaltersatellitecellprogenytoincreasinglyformfibersofasingletype.