RESUMO
Deltex is a component of the Notch signaling network, which mediates cellular differentiation, proliferation, and apoptosis during development. Murine Deltex was initially isolated as a cDNA transcript that displayed increased expression in T-cell tumors induced by gamma irradiation. The in vivo function of Deltex is unknown; however, the emerging role of Notch signaling in T-cell development and lymphomagenesis indirectly supports a role for Deltex in these processes. To investigate the regulation of Deltex expression in both normal and transformed tissue, we have begun analyzing the Deltex genomic locus. Here, we report the exon-intron organization of Deltex and map the locus to the middistal region of mouse chromosome 5, tightly linked to the Adam1a, Lnk, Tbx5, and Nos1 loci. The human homolog of Deltex has been localized to chromosome 12.
Assuntos
Proteínas de Transporte , Mapeamento Cromossômico , Cromossomos Humanos Par 12 , Proteínas/genética , Regiões 3' não Traduzidas , Regiões 5' não Traduzidas , Proteínas ADAM , Proteínas Adaptadoras de Transdução de Sinal , Sequência de Aminoácidos , Animais , Clonagem Molecular , Éxons , Fertilinas , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Íntrons , Masculino , Glicoproteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Metaloendopeptidases/genética , Camundongos , Camundongos Endogâmicos C57BL , Dados de Sequência Molecular , Óxido Nítrico Sintase/genética , Óxido Nítrico Sintase Tipo I , Proteínas/metabolismo , Receptores Notch , Homologia de Sequência de Aminoácidos , Proteínas com Domínio T/genéticaRESUMO
Elucidation of the leukemogenic process induced by fractionated X-irradiation (FX) requires the identification of molecules that mediate the differentiation and regeneration of T cells. To isolate cDNA transcripts associated with FX-induced leukemia in C57BL/6 mice, a cDNA library was constructed from FX-induced thymoma mRNA and differentially screened with cDNA probes. A novel cDNA transcript, FX-induced transcript 1 (FXI-T1), showed strong differential mRNA expression in all C57BL/6 FX-induced thymomas examined when compared with normal thymus tissue. FXI-T1 was not universally expressed in proliferative or other neoplastic cells. Expression of FXI-T1 mRNA in untreated mouse organs was not restricted to the thymus; highest expression was observed in brain and skeletal muscle tissue. The translated FXI-T1 sequence encodes a basic, prolinerich protein that contains a RING-H2-finger motif. The COOH-terminal region of the putative FXI-T1 protein has sequence similarity with the COOH-terminal domain of the Drosophila deltex protein, a component of a signal pathway that functions during cell differentiation. The described observations suggest an association of FXI-T1 with FX-induced leukemogenesis. The study of FXI-T1 should contribute to an understanding of the processes of T-cell differentiation and regeneration in addition to leukemogenesis.
Assuntos
DNA Complementar/biossíntese , Proteínas de Ligação a DNA/biossíntese , Timoma/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Northern Blotting , Sequência Conservada , Biblioteca Gênica , Camundongos , Camundongos Endogâmicos C57BL , Dados de Sequência Molecular , Neoplasias Induzidas por Radiação , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , RNA Mensageiro/genética , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Timoma/etiologia , Distribuição Tecidual/genética , Ubiquitina-Proteína Ligases , Irradiação Corporal TotalRESUMO
A retrovirus element (TLev1) is located within the Thymus leukemia antigen (Tla) locus of the C57BL/10 mouse major histocompatibility complex. Low-copy probes have been isolated from sequences flanking the TLev1 integration site to examine the distribution of TLev1 among inbred mouse strains having genotypically determined variations in TL-antigen expression. It was found that the low-copy probes cross-hybridize to regions within the Tla locus in a genotype-specific manner. Although a strong association was found between TL mouse strains and TLev1, the presence or absence of the TLev1 locus did not exclusively correlate with expression or nonexpression of TL antigens. Analysis of different Mus subspecies indicates that TLev1 integrated into a common ancestor of the species Mus musculus. It is suggested that the loss of the TLev1 locus from certain mouse genomes reflects evolutionary rearrangements in the TL region; the resulting diversity may relate to the differential expression of TL antigens among mouse strains. The probes described here provide a useful tool for examining the genomic expansions and contractions which have occurred during the evolution of the Tla locus.
Assuntos
Haplótipos , Glicoproteínas de Membrana/genética , Camundongos Endogâmicos C57BL/genética , Polimorfismo Genético , Polimorfismo de Fragmento de Restrição , Animais , Reações Cruzadas , DNA/genética , Enzimas de Restrição do DNA , Genes Virais , Marcadores Genéticos , Camundongos , Camundongos Endogâmicos C57BL/imunologia , Hibridização de Ácido Nucleico , Retroviridae/genéticaRESUMO
Early studies of the resistance and susceptibility of mouse strains to radiation-induced leukemia virus have demonstrated the important role of altered histocompatibility (H-2) antigen expression in the effectiveness of the immune response of the host to virus-infected and transformed cells. Changes in H-2 gene expression have now been correlated with disease resistance in a variety of viral systems. The experiments discussed indicate that viruses may directly or indirectly affect H-2 antigen expression at various levels of gene expression. These investigations generate a framework for approaching a molecular understanding of viral-induced changes in H-2 gene expression.
Assuntos
Transformação Celular Viral , Genes MHC Classe I , Antígenos H-2/genética , Animais , Regulação da Expressão Gênica , Leucemia Experimental/genética , Leucemia Experimental/imunologia , Camundongos , Retroviridae/genética , Infecções Tumorais por Vírus/genética , Infecções Tumorais por Vírus/imunologiaRESUMO
Transformation of murine thymocytes by radiation leukemia virus is associated with reduced expression of the class I antigens encoded in the major histocompatibility complex (MHC) and increased methylation and altered restriction enzyme patterns of MHC DNA. These changes may play a role in host susceptibility to virus-induced leukemogenesis and accord with the notion that viral genomes play a regulatory function when they integrate adjacent to histocompatibility genes.
Assuntos
Transformação Celular Viral , Antígenos H-2/genética , Vírus da Leucemia Murina , Leucemia Experimental/genética , Animais , Enzimas de Restrição do DNA , Regulação da Expressão Gênica , Leucemia Experimental/microbiologia , Metilação , Camundongos , Polimorfismo Genético , RNA Mensageiro/genética , Recombinação Genética , Linfócitos T/fisiologia , Transcrição GênicaRESUMO
Two retroviruslike sequences have been isolated from the TL locus of the major histocompatibility complex of C57BL/10 mice. One sequence (TLev2) hybridizes only with probes derived from the pol region of the murine leukemia provirus AKR; the other sequence (TLev1) hybridizes with gag, pol, and env AKR region probes. This 9-kilobase endogenous, TL region-associated virus (TLev1) has been further characterized. The TLev1 genome has been shown to contain murine leukemia virus-related sequences bounded by retroviruslike, VL30 long terminal repeats. Hybridization of TLev1-derived probes to mouse genomic digests reveals multiple copies which show distinct patterns compared with those observed with murine leukemia virus probes. The study of TLev1 may prove significant with respect to the interaction of retroviral sequences within the genome, expression of genes within the TL locus, and polymorphisms within the major histocompatibility complex.
Assuntos
Antígenos de Neoplasias/genética , Genes Virais , Complexo Principal de Histocompatibilidade , Glicoproteínas de Membrana , Camundongos Endogâmicos C57BL/genética , Retroviridae/genética , Vírus AKR da Leucemia Murina/genética , Animais , Sequência de Bases , Clonagem Molecular , Camundongos , Camundongos Endogâmicos C57BL/microbiologia , Hibridização de Ácido Nucleico , Sequências Repetitivas de Ácido Nucleico , Homologia de Sequência do Ácido NucleicoRESUMO
The studies reported here localize murine leukemia viral sequences to the TL region of the major histocompatibility complex, H-2. We examined a battery of 38 cosmids, isolated from two large genomic libraries constructed from C57BL/10 spleen DNA, that define 25 class I gene sequences. The viral probes used hybridized with only four cosmids, containing overlapping mouse sequences, that define four class I gene-related sequences in a region of 90 kilobases of DNA. The data show that two distinct viral envelope sequences are contained in the cluster. One of these sequences is situated with its 3' end next to the 3' end of a class I sequence. The other sequence, which does not contain the entire viral envelope, is proximal to the 3' end of a different class I sequence. Hybridization of the viral probes with the H-2 cosmid clones does not appear to be due to homology between viral and H-2 sequences. Rather, the viral sequences detected appear to be linked to or inserted amid class I genes. These findings may be significant in understanding molecular mechanisms involved in the generation of H-2 class I gene diversity.
Assuntos
Transformação Celular Viral , Genes Virais , Vírus da Leucemia Murina/genética , Complexo Principal de Histocompatibilidade , Animais , Sequência de Bases , Mapeamento Cromossômico , DNA Viral/genética , CamundongosRESUMO
Reaction of the cAMP (cyclic adenosine 3'--5'-monophosphate) receptor protein (CRP) of Escherichia coli with the bifunctional reagent o-phenylenedimaleimide (oPDM) results in the cross-linking of the two subunits of a CRP protomer. In the presence of cAMP the rate of cross-linking increases. CRP modified with oPDM retains [3H]cAMP binding activity but loses [3H]d(I-C)n binding activity. Proteolysis of cross-linked CRP gives distinct sodium dodecyl sulfate-polyacrylamide gel electrophoretic patterns depending upon whether cAMP was present during the reaction with oPDM. CRP cross-linked in the absence of cAMP retains the same relative resistance to proteolysis as unmodified CRP. The presence of 0.1 mM cAMP during proteolysis results in the production of two fragments, one of approximately 13 000 daltons and a second of approximately 20 000 daltons. CRP cross-linked with oPDM in the presence of cAMP (then dialyzed to remove cAMP) remains sensitive to alpha-chymotrypsin digestion even in the absence of added cAMP producing only the 13 000-dalton fragment. It is suggested that the nature of the oPDM cross-link is a consequence of the conformational state of CRP.
