Characterization of a newt tenascin cDNA and localization of tenascin mRNA during newt limb regeneration by in situ hybridization☆

[摘要] Wepreviouslyshowedthattenascin,alarge,extracellularmatrixglycoprotein,exhibitsatemporallyandspatiallyrestricteddistributionduringurodelelimbregeneration.Tofurtherinvestigatetheroleoftenascininregeneration,weclonedanewttenascincDNA,NvTN.1,thathas70%homologytothechickentenascinsequence.AdeducedaminoacidsequenceofNvTN.1showedamodularstructureuniquetotenascincharacterizedbyepidermalgrowthfactor-likeandfibronectintypeIIIrepeats.Todeterminethecellularoriginoftenascinproteinduringlimbregeneration,welocalizedtenascintranscriptsbyinsituhybridizationusingariboprobesynthesizedfromNvTN.1.Transcriptscouldnotbedetectedinnormallimbtissuesbutfirstbecamedetectableinthewouldepitheliumat2daysandinthedistalmesodermat5daysafteramputation.Thesewoundepithelialcellsareprobablythesourceoftenascinproteinfoundwithinandimmediatelyunderneaththewoundepithelium.Atpreblastemastages,hybridizationwasseenincellsassociatedwithmostofthedistalmesodermaltissuesbutnotindermis.Atblastemastages,essentiallyeverymesenchymalcellcontainedtenascintranscripts.Thus,regardlessoforigin,blastemalmesenchymalcellsmayshareacommonregulatorymechanismthatresultsintenascingenetranscription.Finally,duringredifferentiationstagesofregeneration,tenascingenetranscriptionwasassociatedwithbothdifferentiationandgrowth.Theresultsshowthatinitiationoftenascingeneexpressionisanearlyeventinregenerationandcontinuedtenascingenetranscriptionisassociatedwithsomeoftheimportantprocessesofregeneration,namelywouldepithelial-mesenchymalinteractions,dedifferentiation,initiationofcellcycling,blastemaoutgrowth,andcellulardifferentiation.

[学科分类] 生物科学（综合）