RESUMO
We describe the cloning of a full length cDNA encoding the mouse mammalian achaete-scute homolog 1 (mouse MASH1). Using a ribonuclease protection assay to examine expression of this gene in cell lines, postimplantation embryos and adult tissues, expression was detected between days 10.5 and 16.5 of gestation and in adult brain. No expression was detected in other adult tissues or in most of the cell lines examined. However, differentiation of P19 embryonal carcinoma cells into neuronal cell types by exposure to retinoic acid resulted in the induction of MASH1 RNA expression.
Assuntos
Proteínas de Ligação a DNA/genética , Fatores de Transcrição , Sequência de Aminoácidos , Animais , Sequência de Bases , Fatores de Transcrição Hélice-Alça-Hélice Básicos , Encéfalo/metabolismo , Linhagem Celular/metabolismo , Clonagem Molecular , DNA/química , Proteínas de Ligação a DNA/biossíntese , Proteínas de Ligação a DNA/química , Drosophila , Embrião de Mamíferos/metabolismo , Embrião não Mamífero , Camundongos , Dados de Sequência Molecular , Ratos , Homologia de Sequência do Ácido NucleicoRESUMO
We have made a null mutation in the mouse activin beta B gene by deleting the portion of the gene encoding the proteolytic cleavage site and the majority of the coding region for the mature processed protein. Mice homozygous for this mutation complete embryogenesis and are completely viable. Approximately 40% of the homozygous mutant animals are born with open eyes. Aside from the incompletely penetrant eye defects, histopathological analysis has not revealed any other abnormalities in homozygous mutant animals. Breeding tests have shown that both male and female homozygous mutant animals are fertile.
Assuntos
Ativinas , Desenvolvimento Embrionário e Fetal/fisiologia , Fertilidade/fisiologia , Homozigoto , Mutação , Oligopeptídeos , Peptídeos/genética , Adjuvantes Imunológicos/genética , Adjuvantes Imunológicos/fisiologia , Alelos , Animais , Sequência de Bases , Southern Blotting , Linhagem Celular , Embrião de Mamíferos/química , Embrião de Mamíferos/citologia , Desenvolvimento Embrionário e Fetal/genética , Feminino , Genótipo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Dados de Sequência Molecular , Peptídeos/fisiologia , Reação em Cadeia da PolimeraseAssuntos
Sistemas de Identificação Animal , Camundongos Transgênicos , Reação em Cadeia da Polimerase/métodos , Animais , Sequência de Bases , DNA/análise , DNA/metabolismo , Primers do DNA , Marcadores Genéticos , Indicadores e Reagentes , Canamicina Quinase , Camundongos , Dados de Sequência Molecular , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Tireotropina/genética , beta-Galactosidase/genéticaRESUMO
Mice homozygous for a targeted mutation of the Hoxa-2 (Hox 1.11) gene are born with cleft palates and die within 24 hr of birth. Analysis of stained skeletons revealed that homozygous mutant animals contained multiple cranial skeletal defects, including a duplication of the ossification centers of the bones of the middle ear. Histological analysis suggested that this duplication resulted from the transformation of skeletal elements derived from the second branchial arch into more anterior structures, resulting in a duplication of Meckel's cartilage adjacent to the otic capsule. Skeletal elements normally derived from the second arch were absent in the mutants. These data provide direct experimental evidence for the existence of a branchial Hox code.
Assuntos
Genes Homeobox , Cabeça/embriologia , Crista Neural/embriologia , Anormalidades Múltiplas/genética , Animais , Sequência de Bases , Fissura Palatina/embriologia , Fissura Palatina/genética , Nervos Cranianos/embriologia , Primers do DNA/química , Feminino , Masculino , Camundongos , Camundongos Knockout , Dados de Sequência Molecular , Morfogênese , Rombencéfalo/embriologiaRESUMO
The Mov-34 mutation is a recessive embryonic lethal mutation caused by experimental introduction of a recombinant Moloney murine leukemia provirus into the mouse germline. We have cloned a full-length cDNA from the Mov-34 gene, the transcription unit disrupted by the proviral integration. This cDNA is predicted to encode a novel 321-amino acid, 36-kDa protein of unknown function. Overlapping phage lambda clones containing the entire Mov-34 gene have been isolated. The Mov-34 gene spans just over 8 kb and contains seven exons. The 5' flanking region of the Mov-34 gene contains neither "TATA" nor "CAAT" box sequences, and 5' end mapping by primer extension and ribonuclease protection reveal multiple transcription initiation sites.
Assuntos
Genes Letais/genética , Genes Recessivos/genética , Leucemia Experimental/genética , Vírus da Leucemia Murina de Moloney/genética , Proteínas , Proteínas Recombinantes/genética , Proteínas dos Retroviridae/genética , Sequência de Aminoácidos , Animais , Bacteriófago lambda/genética , Sequência de Bases , Clonagem Molecular , DNA/genética , DNA Recombinante , Éxons/genética , Peptídeos e Proteínas de Sinalização Intracelular , Camundongos , Dados de Sequência Molecular , Mutação/genética , Provírus/genética , Proteínas de Ligação a RNA , Ribonucleases/metabolismo , TATA Box/genéticaRESUMO
Goosecoid (gsc) is an evolutionarily conserved homeobox gene expressed in the gastrula organizer region of a variety of vertebrate embryos, including zebrafish, Xenopus, chicken and mouse. To understand the role of gsc during mouse embryogenesis, we generated gsc-null mice by gene targeting in embryonic stem cells. Surprisingly, gsc-null embryos gastrulated and formed the primary body axes; gsc-null mice were born alive but died soon after birth with numerous craniofacial defects. In addition, rib fusions and sternum abnormalities were detected that varied depending upon the genetic background. Transplantation experiments suggest that the ovary does not provide gsc function to rescue gastrulation defects. These results demonstrate that gsc is not essential for organizer activity in the mouse but is required later during embryogenesis for craniofacial and rib cage development.
Assuntos
Proteínas de Ligação a DNA/genética , Ossos Faciais/embriologia , Gástrula/fisiologia , Genes Homeobox , Proteínas de Homeodomínio , Proteínas Repressoras , Costelas/embriologia , Crânio/embriologia , Fatores de Transcrição , Animais , Feminino , Morte Fetal , Expressão Gênica , Marcação de Genes , Proteína Goosecoid , Camundongos , Camundongos Mutantes , Morfogênese/genética , FenótipoRESUMO
The Grg gene encodes a 197 amino acid protein homologous to the amino-terminal domain of the product of the groucho gene of the Drosophila Enhancer of split complex. Analysis with a polyclonal antisera specific for the Grg protein revealed that Grg is a 25 kd nuclear protein that can participate in specific protein-protein interactions. A null mutation of the Grg gene was constructed by gene targeting. Mice homozygous for this mutation completed embryogenesis and were born, but exhibited varying degrees of post-natal growth deficiency. No dosage-sensitive genetic interaction was detected between the Notch1 and Grg genes in mice heterozygous for a Notch1 mutant allele and homozygous for the Grg null mutation.
Assuntos
Proteínas de Ligação a DNA/genética , Proteínas de Drosophila , Hormônios de Inseto/genética , Proteínas/genética , Proteínas Repressoras/genética , Fatores de Transcrição , Alelos , Animais , Sequência de Bases , Fatores de Transcrição Hélice-Alça-Hélice Básicos , Proteínas Correpressoras , Drosophila/genética , Desenvolvimento Embrionário e Fetal/genética , Dosagem de Genes , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Genes Letais/fisiologia , Mutação em Linhagem Germinativa/fisiologia , Homozigoto , Camundongos , Camundongos Mutantes , Dados de Sequência Molecular , Ligação Proteica/fisiologia , Proteínas/metabolismo , RNA Mensageiro/análise , Transcrição Gênica/genéticaRESUMO
The Notch gene of Drosophila encodes a large transmembrane protein involved in cell-cell interactions and cell fate decisions in the Drosophila embryo. We report here the isolation of cDNA clones encompassing the full-length coding sequence of Notch-1, a mouse homolog of Drosophila Notch. The predicted amino acid sequence of the Notch-1 protein retains all of the conserved amino acid motifs of Notch and the other vertebrate Notch homologs. The cDNA sequence predicts a 2531-amino-acid protein containing a signal peptide, 36 epidermal growth factor-like repeats, 3 Notch/lin-12 repeats, a transmembrane domain, and 6 cdc10/ankyrin repeats. The Notch-1 gene was localized to the proximal portion of mouse chromosome 2 by mapping with an interspecific backcross panel.
Assuntos
Mapeamento Cromossômico , Hormônios de Inseto/genética , Proteínas de Membrana/genética , Receptores de Superfície Celular , Fatores de Transcrição , Sequência de Aminoácidos , Animais , Clonagem Molecular , DNA , Drosophila , Proteínas de Drosophila , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Dados de Sequência Molecular , Receptor Notch1 , Receptores Notch , Homologia de Sequência de AminoácidosRESUMO
Homeobox genes are expressed with a specific spatial and temporal order, which is essential for pattern formation during the early development of both invertebrates and vertebrates. Here we show that widespread ectopic expression of the Hoxa-1 (Hox 1.6) gene directed by a human beta-actin promoter in transgenic mice is embryolethal and produces abnormal phenotypes in a subset of domains primarily located in anterior regions. Interestingly, this abnormal development in the Hoxa-1 transgenic mice is associated with ectopic expression of the Hoxb-1 (Hox 2.9) gene in select hindbrain regions. At gestation day 9.5, two domains of strong Hoxb-1 expression are found in the anterior region of the hindbrains of Hoxa-1 transgenic embryos. One region represents the normal pattern of Hoxb-1 expression in rhombomere 4 and its associated migrating neural crest cells, while another major domain of Hoxb-1 expression consistently appears in rhombomere 2. Similar ectopic domains of beta-galactosidase activity are detected in dual transgenic embryos containing both beta-actin/Hoxa-1 transgene and a Hoxb-1/lacZ reporter construct. Expression of another lacZ reporter gene that directs beta-galactosidase activity predominantly in rhombomere 2 is suppressed in the Hoxa-1 transgenic embryos. We have also detected weaker and variable ectopic Hoxb-1 expression in rhombomeres 1, 3 and 6. No ectopic Hoxb-1 expression is detected in rhombomere 5 and the expression of Hoxa-3 and Krox-20 in this region is unchanged in the Hoxa-1 transgenic embryos. While no obvious change in the morphology of the trigeminal or facial-acoustic ganglia is evident, phenotypic changes do occur in neurons that emanate from rhombomeres 2 and 3 in the Hoxa-1 transgenic embryos. Additionally, alterations in the pattern of Hoxa-2 and Hoxb-1 expression in a subpopulation of neural crest cells migrating from the rhombomere 2 region are detected in these transgenics. Taken together, these data suggest that ectopic Hoxa-1 expression can reorganize select regions of the developing hindbrain by inducing partial transformations of several rhombomeres into a rhombomere-4-like identity.
Assuntos
Regulação da Expressão Gênica , Genes Homeobox , Rombencéfalo/embriologia , Transformação Genética , Actinas/genética , Animais , Sequência de Bases , Imuno-Histoquímica , Hibridização In Situ , Camundongos , Camundongos Transgênicos , Dados de Sequência Molecular , Morfogênese/genética , Sistema Nervoso/embriologia , Crista Neural/citologia , Regiões Promotoras GenéticasRESUMO
The Notch gene of Drosophila encodes a large transmembrane protein involved in cell-cell interactions and cell fate decisions in the Drosophila embryo. To determine if a gene homologous to Drosophila Notch plays a role in early mouse development, we screened a mouse embryo cDNA library with probes from the Xenopus Notch homolog, Xotch. A partial cDNA clone encoding the mouse Notch homolog, which we have termed Motch, was used to analyze expression of the Motch gene. Motch transcripts were detected in a wide variety of adult tissues, which included derivatives of all three germ layers. Differentiation of P19 embryonal carcinoma cells into neuronal cell types resulted in increased expression of Motch RNA. In the postimplantation mouse embryo Motch transcripts were first detected in mesoderm at 7.5 days post coitum (dpc). By 8.5 dpc, transcript levels were highest in presomitic mesoderm, mesenchyme and endothelial cells, while much lower levels were detected in neuroepithelium. In contrast, at 9.5 dpc, neuroepithelium was a major site of Motch expression. Transcripts were also abundant in cell types derived from neural crest. These data suggest that the Motch gene plays multiple roles in patterning and differentiation of the early postimplantation mouse embryo.
Assuntos
Sistema Nervoso Central/embriologia , Expressão Gênica/fisiologia , Genes/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Drosophila/genética , Indução Embrionária/genética , Mesoderma/fisiologia , Camundongos , Técnicas de Sonda Molecular , Dados de Sequência Molecular , Morfogênese/genética , Homologia de SequênciaRESUMO
Tie-1 and Tie-2 define a new class of receptor tyrosine kinases that are specifically expressed in developing vascular endothelial cells. To study the functions of Tie-1 and Tie-2 during vascular endothelial cell growth and differentiation in vivo, targeted mutations of the genes in mice were introduced by homologous recombination. Embryos deficient in Tie-1 failed to establish structural integrity of vascular endothelial cells, resulting in oedema and subsequently localized haemorrhage. However, analyses of embryos deficient in Tie-2 showed that it is important in angiogenesis, particularly for vascular network formation in endothelial cells. This result contrasts with previous reports on Tie-2 function in vasculogenesis and/or endothelial cell survival. Our in vivo analyses indicate that the structurally related receptor tyrosine kinases Tie-1 and Tie-2 have important but distinct roles in the formation of blood vessels.
Assuntos
Vasos Sanguíneos/embriologia , Endotélio Vascular/embriologia , Receptores Proteína Tirosina Quinases/fisiologia , Animais , Sequência de Bases , Vasos Sanguíneos/crescimento & desenvolvimento , Diferenciação Celular/fisiologia , Divisão Celular/fisiologia , Linhagem Celular , Primers do DNA , Edema/embriologia , Endotélio Vascular/citologia , Hemorragia/embriologia , Camundongos , Camundongos Endogâmicos C57BL , Dados de Sequência Molecular , Mutagênese , Fenótipo , Receptores Proteína Tirosina Quinases/genética , Receptor de TIE-1 , Receptor TIE-2 , Receptores de TIERESUMO
The Notch signaling pathway is an evolutionarily conserved intercellular signaling mechanism essential for embryonic development in mammals. Mutations in the human JAGGED1 ( JAG1 ) gene, which encodes a ligand for the Notch family of transmembrane receptors, cause the autosomal dominant disorder Alagille syndrome. We have examined the in vivo role of the mouse Jag1 gene by creating a null allele through gene targeting. Mice homozygous for the Jag1 mutation die from hemorrhage early during embryogenesis, exhibiting defects in remodeling of the embryonic and yolk sac vasculature. We mapped the Jag1 gene to mouse chromosome 2, in the vicinity of the Coloboma ( Cm ) deletion. Molecular and complementation analyses revealed that the Jag1 gene is functionally deleted in the Cm mutant allele. Mice heterozygous for the Jag1 null allele exhibit an eye dysmorphology similar to that of Cm /+ heterozygotes, but do not exhibit other phenotypes characteristic of Cm /+ mice or of humans with Alagille syndrome. These results establish the phenotype of Cm /+ mice as a contiguous gene deletion syndrome and demonstrate that Jag1 is essential for remodeling of the embryonic vasculature.