title: Knock-in of diphteria toxin A chain gene at Ins2 locus: effects on islet development and localization of Ins2 expression in the brain.
abstract: We report here knock-in of diphteria toxin A chain (dta) gene at the Ins2 locus, using the strategy previously employed to insert lacZ under control of the Ins2 promoter. Mutant Ins2(dta/+), Ins2(dta/lacZ) or Ins2(lacZ/+) mouse pups were generated by breeding and analyzed to study the effects of toxigenetic beta-cell ablation on islet development and to localize the extrapancreatic Ins2 expression site in the brain. Ins2(dta/+) and Ins2(dta/lacZ) pups developed a severe diabetic ketoacidosis and died rapidly. Histological analysis of their pancreas revealed that beta-cells completely disappeared in their islets as evidenced by loss of lacZ activity or insulin immunonostaining. beta-cell ablation did not alter the size of other islet cell populations which were normal at birth, although the glucagon-cell population was reduced by 85% at embryonic day E12.5. In the brain, comparative analysis of lacZ expression in Ins2(lacZ/+) and Ins2(dta/laZ) mice identified the choroid plexus (CP) as a major Ins2 expression site. This finding was confirmed by RT-PCR analysis of insulin transcripts in RNAs prepared from microdissected wild-type CP. Transcripts for other key beta-cell markers, with the notable exception of Pdx-1, were also found in CP RNAs. These results must revive interest in studies focused on extrapancreatic insulin gene expression.
authors.affiliation: Institut Cochin, INSERM U567, CNRS UMR 8104, Université René Descartes, Département Génétique, Développement et Pathologie Moléculaire, 24 rue du Faubourg Saint-Jacques, 75014 Paris, France.
authors.forename: Luciane
authors.initials: L
authors.lastname: Lamotte
authors.forename: Malene
authors.initials: M
authors.lastname: Jackerott
authors.forename: Danielle
authors.initials: D
authors.lastname: Bucchini
authors.forename: Jacques
authors.initials: J
authors.lastname: Jami
authors.forename: Rajiv L
authors.initials: RL
authors.lastname: Joshi
authors.forename: Louise
authors.initials: L
authors.lastname: Deltour
mesh_terms: D000818:Animals; D002831:Choroid Plexus / Q000378:metabolism* / Q000473:pathology; D016883:Diabetic Ketoacidosis / Q000378:metabolism / Q000473:pathology; D004167:Diphtheria Toxin / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D005822:Genetic Vectors / Q000235:genetics; D007328:Insulin / Q000378:metabolism; D007515:Islets of Langerhans / Q000378:metabolism* / Q000473:pathology; D007763:Lac Operon / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D010179:Pancreas / Q000378:metabolism* / Q000473:pathology; D010446:Peptide Fragments / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic
chemical_list: D004167:Diphtheria Toxin; D007328:Insulin; D010446:Peptide Fragments; C029795:diphtheria toxin fragment A