Transcriptional regulation of Munc13-4 expression in cytotoxic lymphocytes is disrupted by an intronic mutation associated with a primary immunodeficiency

• Published in: The Journal of experimental medicine Vol. 211; no. 6; pp. 1079 - 1091
• Main Authors: Cichocki, Frank, Schlums, Heinrich, Li, Hongchuan, Stache, Vanessa, Holmes, Timothy, Lenvik, Todd R, Chiang, Samuel C C, Miller, Jeffrey S, Meeths, Marie, Anderson, Stephen K, Bryceson, Yenan T
• Format: Journal Article
• Language: English
• Published: United States The Rockefeller University Press 02.06.2014
• Subjects: Blotting, Western; CD8-Positive T-Lymphocytes - immunology; CD8-Positive T-Lymphocytes - metabolism; Cells, Cultured; Cytotoxicity, Immunologic - genetics; Cytotoxicity, Immunologic - immunology; DNA Helicases - genetics; DNA Helicases - immunology; DNA Helicases - metabolism; Gene Expression Regulation - immunology; Humans; Immunologic Deficiency Syndromes - genetics; Immunologic Deficiency Syndromes - immunology; Immunologic Deficiency Syndromes - metabolism; Introns - genetics; Killer Cells, Natural - immunology; Killer Cells, Natural - metabolism; Lymphohistiocytosis, Hemophagocytic - genetics; Lymphohistiocytosis, Hemophagocytic - immunology; Lymphohistiocytosis, Hemophagocytic - metabolism; Medicin och hälsovetenskap; Membrane Proteins - genetics; Membrane Proteins - immunology; Membrane Proteins - metabolism; Nuclear Proteins - genetics; Nuclear Proteins - immunology; Nuclear Proteins - metabolism; Point Mutation - immunology; Protein Binding - genetics; Protein Binding - immunology; Protein Isoforms - genetics; Protein Isoforms - immunology; Protein Isoforms - metabolism; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; STAT4 Transcription Factor - genetics; STAT4 Transcription Factor - immunology; STAT4 Transcription Factor - metabolism; Transcription Factors - genetics; Transcription Factors - immunology; Transcription Factors - metabolism
• ISSN: 0022-1007; 1540-9538; 1540-9538
• DOI: 10.1084/jem.20131131

Autosomal recessive mutations in UNC13D, the gene that encodes Munc13-4, are associated with familial hemophagocytic lymphohistiocytosis type 3 (FHL3). Munc13-4 expression is obligatory for exocytosis of lytic granules, facilitating cytotoxicity by T cells and natural killer (NK) cells. The mechanisms regulating Munc13-4 expression are unknown. Here, we report that Munc13-4 is highly expressed in differentiated human NK cells and effector CD8(+) T lymphocytes. A UNC13D c.118-308C>T mutation, causative of FHL3, disrupted binding of the ETS family member ELF1 to a conserved intronic sequence. This mutation impairs UNC13D intron 1 recruitment of STAT4 and the chromatin remodeling complex component BRG1, diminishing active histone modifications at the locus. The intronic sequence acted as an overall enhancer of Munc13-4 expression in cytotoxic lymphocytes in addition to representing an alternative promoter encoding a novel Munc13-4 isoform. Mechanistically, T cell receptor engagement facilitated STAT4-dependent Munc13-4 expression in naive CD8(+) T lymphocytes. Collectively, our data demonstrates how chromatin remodeling within an evolutionarily conserved regulatory element in intron 1 of UNC13D regulates the induction of Munc13-4 expression in cytotoxic lymphocytes and suggests that an alternative Munc13-4 isoform is required for lymphocyte cytotoxicity. Thus, mutations associated with primary immunodeficiencies may cause disease by disrupting transcription factor binding.