ABSTRACT
A spontaneous point mutation in the coding region of the carboxypeptidase E (CPE) gene in Cpe(fat)/Cpe(fat) mice affects proinsulin processing. Cell lines derived from the pancreatic beta-cells of Cpe(fat)/Cpe(fat) mice were generated by crossing C57BLKS/J-Cpe(fat)/+ mice with NOD mice expressing the simian virus 40 large T oncogene under the control of the rat insulin II promoter. Two cell lines, designated NIT-2 and NIT-3, were cultured from adenomatous islets obtained from F2 littermates and were compared with the NIT-1 cell line previously developed from mice with wild-type CPE. Electron microscopy of the cultured NIT-2 and -3 cells showed increased numbers of enlarged and electron-lucent granules compared with NIT-1 cells. Pro-CPE, but not the mature form of CPE, is present in NIT-2 and -3 cells, and neither pro-CPE nor CPE are secreted into the medium. Immunocytochemistry shows the pro-CPE to be localized to an endoplasmic reticulum-like structure in NIT-3 cells. Proinsulin is less extensively processed in NIT-2 and -3 cells than in NIT-1 cells, indicating that the Cpe(fat) mutation affects both the endopeptidase and carboxypeptidase reactions. The secretion of insulin/proinsulin from NIT-2 and -3 cells is significantly elevated by secretagogues, indicating that CPE is not required for sorting proinsulin into the regulated pathway.
Subject(s)
Carboxypeptidases/genetics , Carboxypeptidases/metabolism , Islets of Langerhans/metabolism , Mice, Transgenic/genetics , Mice, Transgenic/metabolism , Point Mutation , Proinsulin/metabolism , Protein Processing, Post-Translational/physiology , Animals , Blotting, Western , Carboxypeptidase H , Cell Line , Enzyme Precursors/metabolism , Immunohistochemistry , Insulin/biosynthesis , Islets of Langerhans/cytology , Mice , Mice, Inbred C57BL , Mice, Inbred NOD , Microscopy, Electron , RatsABSTRACT
The clinical and histologic features are reported of an autosomal dominant mouse cataract that was first observed as a new mutation in a cross between BALB/cJ and AKR/J. In the homozygous state, the eyes were microphthalmic, and a dense white cataract was present when the eyes opened at day 12. Histologic changes were apparent from birth and as early as 18 days' gestation. Liquefaction started by day 4, and herniation of lens contents posteriorly was seen at day 11. Heterozygous mice had variable expression depending both on their genetic background and age. When the single gene was expressed fully, the cataract appeared as a fetal nuclear white opacity; partial expression gave a nuclear haze to snowflake nuclear opacities. Lop-10 appeared to be an excellent model for studying variable expression of a dominant gene.
Subject(s)
Cataract/genetics , Disease Models, Animal , Animals , Cataract/pathology , Gene Expression , Lens, Crystalline/pathology , Mice , Mice, Inbred AKR/genetics , Mice, Inbred BALB C/genetics , Microphthalmos/pathology , MutationABSTRACT
We have identified restriction fragment length polymorphisms between Mus musculus and Mus spretus for the Chromosome 15 loci Hox-3, Wnt-1, Krt-2, Rar-g, and Ly-6. We followed the inheritance of these alleles in interspecific genetic test crosses between velvet coat (Ve) heterozygotes and M. spretus. The results suggest a gene order and recombination distances (in cM) of Ly-6-22-Wnt-1-2-Ve/Krt-2/Rar-g-3-Hox-3. No recombination was found between Ve, Krt-2, and Rar-g. The data also provide evidence for the hypothesis of a large-scale genomic duplication involving homologous gene pairs on mouse Chromosomes 15 and 11.
Subject(s)
Genes, Developmental , Genes, Homeobox , Genes , Genetic Linkage , Homeodomain Proteins , Mutation , Zebrafish Proteins , Animals , Carrier Proteins/genetics , Chromosome Mapping , Crosses, Genetic , DNA-Binding Proteins/genetics , Female , Hair , Keratins/genetics , Male , Mice , Mice, Inbred BALB C , Polymorphism, Restriction Fragment Length , Proto-Oncogene Proteins/genetics , Receptors, Retinoic Acid , Wnt Proteins , Wnt1 ProteinABSTRACT
Adult C57BL/6J male mice homozygous for the mutant gene, juvenile spermatogonial depletion (jsd/jsd), show azoosper4ia and testes reduced to one-third normal size, but are otherwise phenotypically normal. In contrast, adult jsd/jsd females are fully fertile. This feature facilitated mapping the jsd gene to the centromeric end of chromosome 1; the gene order is jsd-Isocitrate dehydrogenase-1 (Idh-1)-Peptidase-3 (Pep-3). Analysis of testicular histology from jsd/jsd mice aged 3-10 wk revealed that these mutant mice experience one wave of spermatogenesis, but fail to continue mitotic proliferation of type A spermatogonial cells at the basement membrane. As a consequence, histological sections of testes from mutant mice aged 8-52 wk showed tubules populated by modest numbers of Sertoli cells, with only an occasional spermatogonial cell. Some sperm with normal morphology and motility were observed in epididymides of 6.5- but not in 8-wk or older mutants. Treatment with retinol failed to alter the loss of spermatogenesis in jsd/jsd mice. Analyses of serum hormones of jsd/jsd males showed that testosterone levels were normal at all ages--a finding corroborated by normal seminal vesicle and vas deferens weights, whereas serum follicle-stimulating hormone levels were significantly elevated in mutant mice from 4 to 20 wk of age. We hypothesize the jsd/jsd male may be deficient in proliferative signals from Sertoli cells that are needed for spermatogenesis.
Subject(s)
Oligospermia/genetics , Spermatogonia/pathology , Spermatozoa/pathology , Animals , Homozygote , Hormones/blood , Male , Mice , Mice, Inbred C57BL , Mice, Mutant Strains , Oligospermia/blood , Oligospermia/pathology , Spermatogenesis , Testis/drug effects , Testis/pathology , Vitamin A/pharmacologyABSTRACT
Restriction fragment length polymorphisms have been identified between inbred strains of mice for the homeo box gene complex Hox-2. These genetic markers were used to follow the segregation of different Hox-2 alleles among recombinant inbred strains of mice and among the progeny of a three point genetic cross. The results place the Hoax-2 locus approximately 1 cM from the rex (Re) locus on mouse chromosome 11.
