RESUMO
Inappropriate stimulation or defective negative regulation of the type I interferon response can lead to autoinflammation. In genetically uncharacterized cases of the type I interferonopathy Aicardi-Goutières syndrome, we identified biallelic mutations in LSM11 and RNU7-1, which encode components of the replication-dependent histone pre-mRNA-processing complex. Mutations were associated with the misprocessing of canonical histone transcripts and a disturbance of linker histone stoichiometry. Additionally, we observed an altered distribution of nuclear cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS) and enhanced interferon signaling mediated by the cGAS-stimulator of interferon genes (STING) pathway in patient-derived fibroblasts. Finally, we established that chromatin without linker histone stimulates cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) production in vitro more efficiently. We conclude that nuclear histones, as key constituents of chromatin, are essential in suppressing the immunogenicity of self-DNA.
Assuntos
Cromatina/metabolismo , Histonas/metabolismo , Interferon Tipo I/biossíntese , Precursores de RNA/metabolismo , Proteínas de Ligação a RNA/genética , Ribonucleoproteína Nuclear Pequena U7/genética , Doenças Autoimunes do Sistema Nervoso/genética , Doenças Autoimunes do Sistema Nervoso/imunologia , Linhagem Celular , DNA/imunologia , Regulação da Expressão Gênica/genética , Regulação da Expressão Gênica/imunologia , Células HCT116 , Células HEK293 , Doenças Hereditárias Autoinflamatórias/genética , Doenças Hereditárias Autoinflamatórias/imunologia , Humanos , Proteínas de Membrana/metabolismo , Malformações do Sistema Nervoso/genética , Malformações do Sistema Nervoso/imunologia , Nucleotídeos Cíclicos/biossíntese , Nucleotidiltransferases/metabolismoRESUMO
Although ribosomes are ubiquitous and essential for life, recent data indicate that monogenic causes of ribosomal dysfunction can confer a remarkable degree of specificity in terms of human disease phenotype. Box C/D small nucleolar RNAs (snoRNAs) are evolutionarily conserved non-protein-coding RNAs involved in ribosome biogenesis. Here we show that biallelic mutations in the gene SNORD118, encoding the box C/D snoRNA U8, cause the cerebral microangiopathy leukoencephalopathy with calcifications and cysts (LCC), presenting at any age from early childhood to late adulthood. These mutations affect U8 expression, processing and protein binding and thus implicate U8 as essential in cerebral vascular homeostasis.