RESUMO
Our work and that of others defined mitosis-specific (Rad21 subfamily) and meiosis-specific (Rec8 subfamily) proteins involved in sister chromatid cohesion in several eukaryotes, including humans. Mutation of the fission yeast Schizosaccharomyces pombe rec8 gene was previously shown to confer a number of meiotic phenotypes, including strong reduction of recombination frequencies in the central region of chromosome III, absence of linear element polymerization, reduced pairing of homologous chromosomes, reduced sister chromatid cohesion, aberrant chromosome segregation, defects in spore formation, and reduced spore viability. Here we extend the description of recombination reduction to the central regions of chromosomes I and II. We show at the protein level that expression of rec8 is meiosis specific and that Rec8p localizes to approximately 100 foci per prophase nucleus. Rec8p was present in an unphosphorylated form early in meiotic prophase but was phosphorylated prior to meiosis I, as demonstrated by analysis of the mei4 mutant blocked before meiosis I. Evidence for the persistence of Rec8p beyond meiosis I was obtained by analysis of the mutant mes1 blocked before meiosis II. A human gene, which we designate hrec8, showed significant primary sequence similarity to rec8 and was mapped to chromosome 14. High mRNA expression of mouse and human rec8 genes was found only in germ line cells, specifically in testes and, interestingly, in spermatids. hrec8 was also expressed at a low level in the thymus. Sequence similarity and testis-specific expression indicate evolutionarily conserved functions of Rec8p in meiosis. Possible roles of Rec8p in the integration of different meiotic events are discussed.
Assuntos
Proteínas de Ciclo Celular , Cromátides/genética , Proteínas Fúngicas/genética , Meiose/genética , Proteínas Nucleares/genética , Fosfoproteínas/genética , Recombinação Genética/genética , Proteínas de Schizosaccharomyces pombe , Sequência de Aminoácidos , Mapeamento Cromossômico , Cromossomos/genética , Cromossomos Humanos Par 14 , Clonagem Molecular , Proteínas de Ligação a DNA , Células Eucarióticas , Evolução Molecular , Proteínas Fúngicas/metabolismo , Expressão Gênica/genética , Teste de Complementação Genética , Células Germinativas/metabolismo , Humanos , Imuno-Histoquímica , Dados de Sequência Molecular , Mutação/genética , Fosforilação , Filogenia , RNA Mensageiro/metabolismo , Saccharomyces/genética , Alinhamento de Sequência , Análise de Sequência de DNARESUMO
Interlineage human-mouse hybrids were constructed by fusion of human acute undifferentiated leukaemia cells with the mouse thymoma cell line BW5147. Some of the hybrids expressed the human differentiation antigens CD4, CD7, CD33, and CD71 (transferrin receptor). Chromosome analysis revealed that the expression of the myeloid antigen CD33 is dependent on the presence of human chromosome 19, which is in agreement with the location of CD33-coding sequences on chromosome 19, as recently reported by Peiper et al. (1987). Furthermore, these hybrids allowed us to confirm the assignment of the CD4 antigen, the CD7 antigen, and the CD71 antigen to human chromosomes 12, 17 and 3, respectively.
Assuntos
Antígenos CD/genética , Antígenos de Diferenciação Mielomonocítica/genética , Cromossomos Humanos Par 19 , Leucemia/genética , Adulto , Animais , Antígenos CD/biossíntese , Antígenos CD7 , Antígenos de Diferenciação Mielomonocítica/biossíntese , Antígenos de Diferenciação de Linfócitos T/biossíntese , Antígenos de Diferenciação de Linfócitos T/genética , Antígenos CD4/biossíntese , Antígenos CD4/genética , Bandeamento Cromossômico , Humanos , Células Híbridas , Masculino , Camundongos , Receptores da Transferrina/biossíntese , Receptores da Transferrina/genética , Lectina 3 Semelhante a Ig de Ligação ao Ácido Siálico , Células Tumorais CultivadasRESUMO
Human-murine myeloid somatic cell hybrids were assayed for the expression of the myeloid-associated sialyl-X determinant. This determinant is expressed at the surface of hybrid cells containing human chromosome 11, but its expression could not be correlated with the presence of the sialyltransferase which is involved in the sialyl-X synthesis. The sialyl-X determinant, however, is simultaneously expressed with another alpha 2----3-sialyltransferase activity, which is involved in the sialylation of the O-linked Gal beta 1----3GalNAc alpha-R core structure. Chromosomal analyses and enzymatic data suggest that human chromosome 11 is involved in the expression of both the sialyl-X antigen and this alpha 2----3-sialyltransferase.
Assuntos
Antígenos de Neoplasias/análise , Cromossomos Humanos Par 11 , Epitopos/análise , Leucemia Mieloide/imunologia , Antígenos do Grupo Sanguíneo de Lewis , Sialiltransferases/análise , Animais , Humanos , Células Híbridas/enzimologia , Camundongos , Sialiltransferases/genéticaRESUMO
We have constructed somatic cell hybrids between the murine T cell line BW5147 and cells from patients suffering from T cell acute lymphoblastic leukemia. The obtained hybrid clones were analyzed for expression of human T cell antigens and presence of human chromosomes. T cell hybrids derived from fusion between the BW5147 cell line and bone marrow cells from a patient with pre-T acute lymphoblastic leukemia (TdT+/HLA-DR+/Tp41+/T11+/T1-/T6-/T4-/T8-/T3-) appeared to express the human T cell antigen Tp41, which can be recognized by the monoclonal antibodies 3A1 and WT1. Although this panel of hybrid cells contained all human chromosomes, no other T cell antigens were expressed. Fusion of the BW5147 cell line with peripheral blood cells from a patient with a more mature T cell acute lymphoblastic leukemia (TdT+/HLA-DR+/Tp41+/T11+/T1+/T6-/T4+/T8+/T3-) resulted in a panel of hybrid clones that expressed not only the Tp41 antigen, but also the human T cell antigens T1 and T4; two hybrids even expressed the T3 antigen. This panel of hybrids also contained the whole human genome. The two panels of human-mouse T cell hybrids allowed us to assign the genes coding for the human T cell antigens Tp41, T1, and T4 to human chromosomes 17, 11, and 12, respectively. Furthermore, these data support our previous suggestion that the expression of human lymphoid differentiation antigens in human-mouse lymphoid hybrids is influenced by the differentiation stage of the fusion partners.