Inhibition of cell differentiation and cell cohesion by tunicamycin in Dictyostelium discoideum☆

[摘要] TheeffectsoftunicamycinonproteinglycosylationandcelldifferentiationwereexaminedduringearlydevelopmentofDictyosteliumdiscoideum.Tunicamycininhibitedcellgrowthreversiblyinliquidmedium.Ataconcentrationof3μg/ml,tunicamycincompletelyinhibitedmorphogenesisandcelldifferentiationindevelopingcells.Thesecellsremainedasasmoothlawnandfailedtoundergochemotacticmigration.TheexpressionofEDTA-resistantcontactsiteswasalsoinhibited.Theinhibitionbytunicamycinwasreversibleifcellswerewashedfreeofthedrugwithinthefirst10hrofincubation.After12hrofdevelopment,cellswereprotectedfromthedrugbythesheath.Whencellsweretreatedwithtunicamycinduringthefirst10hrofdevelopment,incorporationof[3H]mannoseand[3H]fucosewasinhibitedbyapproximately75%within45minwhilenosignificantinhibitionof[3H]leucineincorporationwasobservedduringtheinitial3hrofdrugtreatment.Theinhibitionofproteinglycosylationwasfurtherevidencedbythereductioninnumberofglycoproteins“stained”with125I-labelledconA.Anumberofdevelopmentallyregulatedhigh-molecular-weightglycoproteins,includingthecontactsiteAglycoprotein(gp80),wereundetectablewhencellswerelabelledwith[3H]fucoseinthepresenceoftunicamycin.ItisthereforeevidentthatglycoproteinswithN-glycosidicallylinkedcarbohydratemoietiesmayplayacrucialroleinintercellularcohesivenessandearlydevelopmentofD.discoideum.

[学科分类] 生物科学（综合）