Knock-in of diphteria toxin A chain gene at Ins2 locus: effects on islet development and localization of Ins2 expression in the brain

• Published in: Transgenic research 2004-10, Vol.13 (5), p.463-473
• Main Authors: LAMOTTE, Luciane, JACKEROTT, Malene, BUCCHINI, Danielle, JAMI, Jacques, JOSHI, Rajiv L, DELTOUR, Louise
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Biotechnology; Choroid Plexus; Choroid Plexus - metabolism; Choroid Plexus - pathology; Comparative analysis; Diabetic Ketoacidosis; Diabetic Ketoacidosis - metabolism; Diabetic Ketoacidosis - pathology; Diphtheria Toxin; Diphtheria Toxin - genetics; Diphtheria Toxin - metabolism; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Regulation, Developmental; Genetic engineering; Genetic technics; Genetic Vectors; Genetic Vectors - genetics; Insulin; Insulin - metabolism; Islets of Langerhans; Islets of Langerhans - metabolism; Islets of Langerhans - pathology; Lac Operon; Lac Operon - genetics; Life Sciences; Methods. Procedures. Technologies; Mice; Mice, Transgenic; Pancreas; Pancreas - metabolism; Pancreas - pathology; Peptide Fragments; Peptide Fragments - genetics; Peptide Fragments - metabolism; Promoter Regions, Genetic; Rodents; Transgenic animals and transgenic plants
• ISSN: 0962-8819; 1573-9368
• DOI: 10.1007/s11248-004-9587-x

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.