Loss of ascl1a prevents secretory cell differentiation within the zebrafish intestinal epithelium resulting in a loss of distal intestinal motility

摘要

Thevertebrateintestinalepitheliumisrenewedcontinuouslyfromstemcellsatthebaseofthecryptinmammalsorbaseofthefoldinfishoverthelifeoftheorganism.Asstemcellsdivide,newlyformedepithelialcellsmakeaninitialchoicebetweenasecretoryorenterocytefate.ThischoicehaspreviouslybeendemonstratedtoinvolveNotchsignalingaswellasAtonalandHertranscriptionfactorsinbothembryogenesisandadults.Here,wedemonstratethatincontrasttotheematoh1/eminmammals,emascl1a/emisresponsibleforformationofsecretorycellsinzebrafish.emascl1aminus;/minus;/emembryoslackallintestinalepithelialsecretorycellsandinsteaddifferentiateintoenterocytes.emascl1aminus;/minus;/emembryosalsofailtoinduceintestinalepithelialexpressionofemdeltaD/emsuggestingthatemascl1a/emplaysaroleininitiationofNotchsignaling.InhibitionofNotchsignalingincreasesthenumberofemascl1a/emandemdeltaD/emexpressingintestinalepithelialcellsaswellasthenumberofdevelopingsecretorycellsduringtwospecifictimeperiods:between30and34#xA0;hpfandagainbetween64and74#xA0;hpf.Lossofenteroendocrineproductsresultsinlossofanterogrademotilityinemascl1aminus;/minus;/emembryos.5HTproducedbyenterochromaffincellsiscriticalinmotilityandsecretionwithintheintestine.Wefindthatadditionofexogenous5HTtoemascl1aminus;/minus;/emembryosatnearphysiologicallevels(measuredbydifferentialpulsevoltammetry)induceanterogrademotilityatsimilarlevelstowildtypevelocity,distance,andfrequency.Removalordoublingtheconcentrationof5HTinWTembryosdoesnotsignificantlyaffectanterogrademotility,suggestingthatthelossofadditionalenteroendocrineproductsinemascl1aminus;/minus;/emembryosalsocontributestointestinalmotility.Thus,zebrafishintestinalepithelialcellsappeartohaveacommonsecretoryprogenitorfromwhichallsubtypesform.Lossofenteroendocrinecellsrevealsthecriticalneedforenteroendocrineproductsinmaintenanceofnormalintestinalmotility./p/div