Protein patterns of developmentally totipotent mouse teratocarcinoma cells and normal early embryo cells☆

[摘要] Proteinpatternsofmouseteratocarcinomastemcellswerecompared,bytwo-dimensionalgelelectrophoresis,withthoseofearlyembryocells.Thesemalignantcellswereknownfrompreviousexperiments(B.MintzandK.Illmensee,1975,Proc.Nat.Acad.Sci.USA72,3585–3589)tobecapableofconversiontonormalcyandofcontributingtoembryogenesiswhenintroducedintoablastocyst.Theproteincomparisonswereintendedtorevealwhethertotipotentteratocarcinomacellsmostnearlyresemblenormaltotipotentcellsofaspecificstage,asapossiblecluetotheirdevelopmentalorigins.Asimplemethodwasdevisedforthepurposeofgenerallyfacilitatingcomparisonsoftwo-dimensionalgels,amongwhichtechnicalvariationscommonlyaltertheabsolutepositionsofindividualproteins.Thisvariationwasnormalizedbytheuseofareferenceconstellation,oranetworkoflinesconnectingsharedlandmarkproteinsidentifiedinallthegels.Whereasthenetworkmayundergotopologicalchangefromonegeltoanother,itcontinuestoprovideareadilyrecognizedstandardofreference.Proteinpatternsdisplayedmanysimilaritiesandsomedifferences,hencenonidentity,betweenteratocarcinomacellsandallnormalpreimplantationembryostagestested,aswellasbetweenthevariousembryostagesthemselves.Theresultsalsounexpectedlydisclosed,however,thatchangedphysiologicalstatesorposttranslationalalterationsmaycontributesignificantlytosomeoftheproteindifferencesirrespectiveofthedevelopmentalstatusorpotentialitiesofthecells.Forexample,intheOTT6050teratocarcinomatransplantline,pureteratocarcinomacellgroups(“cores”)foundintheascitesfluidsynthesizedseveralproteinsnotexpressedwhenthecoreswereenveloped(inembryoidbodies)byayolksaclikeepithelium;yetthecorecellsfrombothsourcesformcomparabletumorsifinjectedsubcutaneouslyandareabletoundergodifferentiationifinjectedintoblastocysts.Inanothercomparison,someproteinsthatwerepresentininnercellmassesisolatedfromblastocystswereabsentinintactblastocysts,possiblybecauseoftheirmodificationbythesurroundingtrophoblastinthelattercase.Theseobservationsimplythatproteindifferencesbetweenembryoregionsorstages,howeverreal,arenotnecessarilyrelevantforanevaluationoftheirdevelopmentalprospects.

[学科分类] 生物科学（综合）