RESUMO
Pseudo-TORCH syndrome (PTS) is characterized by microcephaly, enlarged ventricles, cerebral calcification, and, occasionally, by systemic features at birth resembling the sequelae of congenital infection but in the absence of an infectious agent. Genetic defects resulting in activation of type 1 interferon (IFN) responses have been documented to cause Aicardi-Goutières syndrome, which is a cause of PTS. Ubiquitin-specific peptidase 18 (USP18) is a key negative regulator of type I IFN signaling. In this study, we identified loss-of-function recessive mutations of USP18 in five PTS patients from two unrelated families. Ex vivo brain autopsy material demonstrated innate immune inflammation with calcification and polymicrogyria. In vitro, patient fibroblasts displayed severely enhanced IFN-induced inflammation, which was completely rescued by lentiviral transduction of USP18. These findings add USP18 deficiency to the list of genetic disorders collectively termed type I interferonopathies. Moreover, USP18 deficiency represents the first genetic disorder of PTS caused by dysregulation of the response to type I IFNs. Therapeutically, this places USP18 as a promising target not only for genetic but also acquired IFN-mediated CNS disorders.
Assuntos
Doenças Autoimunes do Sistema Nervoso , Encéfalo/imunologia , Calcinose , Endopeptidases/deficiência , Imunidade Inata , Interferon Tipo I/imunologia , Microglia/imunologia , Malformações do Sistema Nervoso , Transdução de Sinais , Doenças Autoimunes do Sistema Nervoso/genética , Doenças Autoimunes do Sistema Nervoso/imunologia , Doenças Autoimunes do Sistema Nervoso/patologia , Encéfalo/patologia , Calcinose/genética , Calcinose/imunologia , Calcinose/patologia , Endopeptidases/imunologia , Feminino , Humanos , Interferon Tipo I/genética , Masculino , Microglia/patologia , Malformações do Sistema Nervoso/genética , Malformações do Sistema Nervoso/imunologia , Malformações do Sistema Nervoso/patologia , Transdução de Sinais/genética , Transdução de Sinais/imunologia , Ubiquitina TiolesteraseAssuntos
Cistatina B/genética , Deficiências do Desenvolvimento/diagnóstico , Deficiências do Desenvolvimento/genética , Discinesias/genética , Microcefalia/diagnóstico , Microcefalia/genética , Pré-Escolar , Comorbidade , Discinesias/diagnóstico , Estudos de Associação Genética , Marcadores Genéticos/genética , Predisposição Genética para Doença/genética , Humanos , Incidência , Lactente , Masculino , Mutação/genética , Polimorfismo de Nucleotídeo Único/genética , Medição de RiscoRESUMO
RAD52 and RAD54 genes from Saccharomyces cerevisiae are required for double-strand break repair through homologous recombination and show epistatic interactions i.e., single and double mutant strains are equally sensitive to DNA damaging agents. In here we combined mutations in RAD52 and RAD54 homologs in Schizosaccharomyces pombe and mice. The analysis of mutant strains in S. pombe demonstrated nearly identical sensitivities of rhp54, rad22A and rad22B double and triple mutants to X-rays, cis-diamminedichloroplatinum and hydroxyurea. In this respect, the fission yeast homologs of RAD54 and RAD52 closely resemble their counterparts in S. cerevisiae. To verify if inactivation of RAD52 affects the DNA damage sensitivities of RAD54 deficient mice, several endpoints were studied in double mutant mice and in bone marrow cells derived from these animals. Haemopoietic depression in bone marrow and the formation of micronuclei after in vivo exposure to mitomycine C (MMC) was not increased in either single or double mutant mice in comparison to wildtype animals. The induction of sister chromatid exchanges in splenocytes was slightly reduced in the RAD54 mutant. A similar reduction was detected in the double mutant. However, a deficiency of RAD52 exacerbates the MMC survival of RAD54 mutant mice and also has a distinct effect on the survival of bone marrow cells after exposure to ionizing radiation. These findings may be explained by additive defects in HR in the double mutant but may also indicate a more prominent role for single-strand annealing in the absence of Rad54.
Assuntos
Proteínas Nucleares/genética , Schizosaccharomyces/genética , Alquilantes/farmacologia , Animais , Medula Óssea/efeitos dos fármacos , Dano ao DNA/genética , DNA Helicases/genética , Proteínas de Ligação a DNA/genética , Resistencia a Medicamentos Antineoplásicos/genética , Epistasia Genética , Eritrócitos/efeitos dos fármacos , Feminino , Hematopoese/genética , Hematopoese/efeitos da radiação , Masculino , Camundongos , Camundongos Knockout , Testes para Micronúcleos , Mitomicina/toxicidade , Mutação , Tolerância a Radiação/genética , Proteínas de Schizosaccharomyces pombe/genética , Troca de Cromátide Irmã/genéticaRESUMO
In meiotic prophase, synaptonemal complexes (SCs) closely appose homologous chromosomes (homologs) along their length. SCs are assembled from two axial elements (AEs), one along each homolog, which are connected by numerous transverse filaments (TFs). We disrupted the mouse gene encoding TF protein Sycp1 to analyze the role of TFs in meiotic chromosome behavior and recombination. Sycp1(-/-) mice are infertile, but otherwise healthy. Sycp1(-/-) spermatocytes form normal AEs, which align homologously, but do not synapse. Most Sycp1(-/-) spermatocytes arrest in pachynema, whereas a small proportion reaches diplonema, or, exceptionally, metaphase I. In leptotene Sycp1(-/-) spermatocytes, gammaH2AX (indicative of DNA damage, including double-strand breaks) appears normal. In pachynema, Sycp1(-/-) spermatocytes display a number of discrete gammaH2AX domains along each chromosome, whereas gammaH2AX disappears from autosomes in wild-type spermatocytes. RAD51/DMC1, RPA, and MSH4 foci (which mark early and intermediate steps in pairing/recombination) appear in similar numbers as in wild type, but do not all disappear, and MLH1 and MLH3 foci (which mark late steps in crossing over) are not formed. Crossovers were rare in metaphase I of Sycp1(-/-) mice. We propose that SYCP1 has a coordinating role, and ensures formation of crossovers. Unexpectedly, Sycp1(-/-) spermatocytes did not form XY bodies.