RESUMO
DNA methylation is a fundamental epigenetic modification, important across biological processes. The maintenance methyltransferase DNMT1 is essential for lineage differentiation during development, but its functions in tissue homeostasis are incompletely understood. We show that epidermis-specific DNMT1 deletion severely disrupts epidermal structure and homeostasis, initiating a massive innate immune response and infiltration of immune cells. Mechanistically, DNA hypomethylation in keratinocytes triggered transposon derepression, mitotic defects, and formation of micronuclei. DNA release into the cytosol of DNMT1-deficient keratinocytes activated signaling through cGAS and STING, thus triggering inflammation. Our findings show that disruption of a key epigenetic mark directly impacts immune and tissue homeostasis, and potentially impacts our understanding of autoinflammatory diseases and cancer immunotherapy.
Assuntos
Metilação de DNA , Dermatite/genética , Epiderme/fisiopatologia , Nucleotidiltransferases/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Aberrações Cromossômicas , Citosol/fisiologia , DNA (Citosina-5-)-Metiltransferase 1/genética , Dermatite/imunologia , Dermatite/patologia , Humanos , Imunidade Inata/genética , Helicase IFIH1 Induzida por Interferon/metabolismo , Queratinócitos/imunologia , Queratinócitos/metabolismo , Queratinócitos/patologia , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos Transgênicos , Nucleotidiltransferases/genéticaRESUMO
Molecular mechanisms that maintain lineage integrity of helper T cells are largely unknown. Here we show histone deacetylases 1 and 2 (HDAC1 and HDAC2) as crucial regulators of this process. Loss of HDAC1 and HDAC2 during late T cell development led to the appearance of major histocompatibility complex (MHC) class II-selected CD4(+) helper T cells that expressed CD8-lineage genes such as Cd8a and Cd8b1. HDAC1 and HDAC2-deficient T helper type 0 (TH0) and TH1 cells further upregulated CD8-lineage genes and acquired a CD8(+) effector T cell program in a manner dependent on Runx-CBFß complexes, whereas TH2 cells repressed features of the CD8(+) lineage independently of HDAC1 and HDAC2. These results demonstrate that HDAC1 and HDAC2 maintain integrity of the CD4 lineage by repressing Runx-CBFß complexes that otherwise induce a CD8(+) effector T cell-like program in CD4(+) T cells.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Histona Desacetilase 1/metabolismo , Histona Desacetilase 2/metabolismo , Células Th1/imunologia , Animais , Diferenciação Celular/genética , Linhagem da Célula/genética , Células Cultivadas , Subunidades alfa de Fatores de Ligação ao Core/metabolismo , Subunidade beta de Fator de Ligação ao Core/metabolismo , Citocinas/metabolismo , Citotoxicidade Imunológica/genética , Antígenos de Histocompatibilidade Classe II/genética , Antígenos de Histocompatibilidade Classe II/metabolismo , Histona Desacetilase 1/genética , Histona Desacetilase 2/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Ligação ProteicaRESUMO
The histone deacetylases HDAC1 and HDAC2 remove acetyl moieties from lysine residues of histones and other proteins and are important regulators of gene expression. By deleting different combinations of Hdac1 and Hdac2 alleles in the epidermis, we reveal a dosage-dependent effect of HDAC1/HDAC2 activity on epidermal proliferation and differentiation. Conditional ablation of either HDAC1 or HDAC2 in the epidermis leads to no obvious phenotype due to compensation by the upregulated paralogue. Strikingly, deletion of a single Hdac2 allele in HDAC1 knockout mice results in severe epidermal defects, including alopecia, hyperkeratosis, hyperproliferation and spontaneous tumour formation. These mice display impaired Sin3A co-repressor complex function, increased levels of c-Myc protein, p53 expression and apoptosis in hair follicles (HFs) and misregulation of HF bulge stem cells. Surprisingly, ablation of HDAC1 but not HDAC2 in a skin tumour model leads to accelerated tumour development. Our data reveal a crucial function of HDAC1/HDAC2 in the control of lineage specificity and a novel role of HDAC1 as a tumour suppressor in the epidermis.
