Transgenic Mice Expressing A Mutant Human GH Gene Causing Type II IGHD

国立情報学研究所で電子化したコンテンツを使用している。We identified several mutations in the intron 3 of human growth hormone gene I (hGH-I) in patients with isolated GH deficiency (IGHD) type II characterized by an autosomal dominant trait. The mutations result in exon 3 skipping and generation of 17 Kd mutant GH. To elucidate how the mutation causes dominant trait, transgenic mice expressing a mutant hGH gene (the first guanine to adenine transversion in intron 3: GH-I; IVS3+1: G-A) were produced in C57BL/6 strain. Genotypes of mice were identified by PCR-amplified products of tail snip DNAs. Delivery of the mutant hGH transgene into 76 fertilized eggs resulted in production of two male heterozygous transgenic mice (hGH^<+/->, the zero filial generation, FO). Since the mating of the transgenic mice with the same strain was unsuccessful, they were outcrossed with CD-I (ICR) strain. Only one mouse gave birth, producing 4 male and 7 female (F1) harboring the mutant hGH gene in one allele (hGH^<+/->). F1 mice were mated again with the wild type ICR strain, generating 82 hGH+/" mice (F2 : 51 males and 31 females). To study whether somatotrophs in F2 mice express the mutant hGH gene, RNA extracted from the pituitary was subjected to RT-PCR. It was demonstrated that the F2, hGH^<+/-> mice express the mutant hGH gene, lacking exon 3. Thus, these heterozygous mice were sib-mated to generate homozygous mice (F3). The mating resulted in 27% hGH^<-/->, 64% hGH+/ and 9% hGH^<+/+> mice, indicating that the transgene was carried stably to the descendants and did not interfere with the reproduction. These mice will be a valuable model to study how type II IGHD develops during the course of development