RESUMO
Ocular coloboma is a congenital defect resulting from failure of normal closure of the optic fissure during embryonic eye development. This birth defect causes childhood blindness worldwide, yet the genetic etiology is poorly understood. Here, we identified a novel homozygous mutation in the SALL2 gene in members of a consanguineous family affected with non-syndromic ocular coloboma variably affecting the iris and retina. This mutation, c.85G>T, introduces a premature termination codon (p.Glu29*) predicted to truncate the SALL2 protein so that it lacks three clusters of zinc-finger motifs that are essential for DNA-binding activity. This discovery identifies SALL2 as the third member of the Drosophila homeotic Spalt-like family of developmental transcription factor genes implicated in human disease. SALL2 is expressed in the developing human retina at the time of, and subsequent to, optic fissure closure. Analysis of Sall2-deficient mouse embryos revealed delayed apposition of the optic fissure margins and the persistence of an anterior retinal coloboma phenotype after birth. Sall2-deficient embryos displayed correct posterior closure toward the optic nerve head, and upon contact of the fissure margins, dissolution of the basal lamina occurred and PAX2, known to be critical for this process, was expressed normally. Anterior closure was disrupted with the fissure margins failing to meet, or in some cases misaligning leading to a retinal lesion. These observations demonstrate, for the first time, a role for SALL2 in eye morphogenesis and that loss of function of the gene causes ocular coloboma in humans and mice.
Assuntos
Códon sem Sentido , Coloboma/genética , Fatores de Transcrição/genética , Adolescente , Animais , Criança , Consanguinidade , Análise Mutacional de DNA , Proteínas de Ligação a DNA , Olho/embriologia , Olho/patologia , Proteínas do Olho/genética , Proteínas do Olho/metabolismo , Feminino , Expressão Gênica , Genes Recessivos , Estudos de Associação Genética , Predisposição Genética para Doença , Células HEK293 , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Homozigoto , Humanos , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fator de Transcrição PAX2/genética , Fator de Transcrição PAX2/metabolismo , Fator de Transcrição PAX6 , Fatores de Transcrição Box Pareados/genética , Fatores de Transcrição Box Pareados/metabolismo , Linhagem , Polimorfismo de Nucleotídeo Único , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Fatores de Transcrição/metabolismoRESUMO
Four homologs to the Drosophila homeotic gene spalt (sal) exist in both humans and mice (SALL1 to SALL4/Sall1 to Sall4, respectively). Mutations in both SALL1 and SALL4 result in the autosomal-dominant developmental disorders Townes-Brocks and Okihiro syndrome, respectively. In contrast, no human diseases have been associated with SALL2 to date, and Sall2-deficient mice have shown no apparent abnormal phenotype. We generated mice deficient in Sall2 and, contrary to previous reports, 11% of our Sall2-deficient mice showed background-specific neural tube defects, suggesting that Sall2 has a role in neurogenesis. To investigate whether Sall4 may compensate for the absence of Sall2, we generated compound Sall2 knockout/Sall4 genetrap mutant mice. In these mutants, the incidence of neural tube defects was significantly increased. Furthermore, we found a similar phenotype in compound Sall1/4 mutant mice, and in vitro studies showed that SALL1, SALL2, and SALL4 all co-localized in the nucleus. We therefore suggest a fundamental and redundant function of the Sall proteins in murine neurulation, with the heterozygous loss of a particular SALL protein also possibly compensated in humans during development.
Assuntos
Tubo Neural/embriologia , Tubo Neural/metabolismo , Fatores de Transcrição/metabolismo , Animais , Apoptose , Proteínas de Ligação a DNA/deficiência , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Embrião de Mamíferos/anormalidades , Embrião de Mamíferos/patologia , Regulação da Expressão Gênica no Desenvolvimento , Marcação de Genes , Peptídeos e Proteínas de Sinalização Intracelular/deficiência , Peptídeos e Proteínas de Sinalização Intracelular/genética , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Camundongos , Mutação/genética , Crista Neural/metabolismo , Crista Neural/patologia , Defeitos do Tubo Neural/metabolismo , Defeitos do Tubo Neural/patologia , Neurulação , Crânio/embriologia , Crânio/metabolismo , Fatores de Transcrição/deficiência , Fatores de Transcrição/genéticaRESUMO
Highly immunodominant marker antigens simply blended to existing veterinary vaccines may represent a smart approach for addressing the still open issue of vaccination compliance. This approach was evaluated by blending a widely deployed Mycoplasma hyopneumoniae vaccine with a peptide-KLH (Keyhole Limpet Hemocyanin) conjugate as marker. Piglets were vaccinated twice with: (i) a combination of the M. hyopneumoniae-specific vaccine and the marker, (ii) M. hyopneumoniae-specific vaccine, (iii) marker alone or (iv) placebo dose only. All piglets which received the M. hyopneumoniae-specific vaccine/marker formulation or, as control, the marker blended with Montanide IMS1313 adjuvant responded to the respective immunisation from day 21 to 77 post vaccination as seropositive for the appropriate peptide and KLH. However, the responder rate to M. hyopneumoniae of piglets administered with M. hyopneumoniae-specific vaccine/marker was slightly reduced at day 35 and 49 post immunisation in comparison with piglets vaccinated with M. hyopneumoniae-specific vaccine alone. Accordingly, we conclude that this marker technology could be successfully applied to label a whole set of vaccines prevented that the blending process will be optimised.