interleukin-8 and Immunologic-Deficiency-Syndromes

Mutations of the DNA methyltransferase 3B (DNMT3B) gene have been detected in patients with immunodeficiency, centromere instability, and facial anomalies (ICF) syndrome. Most of these mutations are clustered in its catalytic domain and thus lead to defective DNA methylation. Nevertheless, the S270P mutation in the N-terminal PWWP (Pro-Trp-Trp-Pro) domain of the DNMT3B gene has prompted questions as to how this mutation contributes to the development of ICF syndrome. In this study, we found that wild-type DNMT3B is SUMOylated through covalent modification, whereas the S270P mutant interacts with SUMO-1 via non-covalent interaction. The S270P mutation results in diffuse nucleus localization. Moreover, the S270P mutant fails to interact with PIAS1, a small ubiquitin-related modifier (SUMO) E3 ligase, and causes the constitutive activation of nuclear factor-kappa B, which induces the expression of interleukin 8. Collectively, our data demonstrate that the S270P mutation affects DNMT3B functions via specific, non-covalent interaction with SUMO-1.

Topics: Cell Line, Tumor; Cell Nucleus; Centromere; Chromosomal Instability; Craniofacial Abnormalities; DNA (Cytosine-5-)-Methyltransferases; DNA Methyltransferase 3B; Face; Humans; Immunologic Deficiency Syndromes; Interleukin-8; NF-kappa B; Point Mutation; Promoter Regions, Genetic; Protein Binding; Protein Inhibitors of Activated STAT; Small Ubiquitin-Related Modifier Proteins; SUMO-1 Protein; Syndrome; Transcription Factors; Transcription, Genetic

In neutrophils, superoxide anion production generally accompanies chemotaxis and functions in killing invading pathogens. The GIT2 GTPase-activating protein binds to the guanine nucleotide-exchange factor alphaPIX. Here we show that GIT2 was necessary for directional chemotaxis and for the suppression of superoxide production in G protein-coupled receptor-stimulated neutrophils. GIT2 was also necessary for the orientation of superoxide production toward chemoattractant sources. GIT2 suppressed the activity of ADP ribosylation factor 1 and was a component of the Gbetagamma subunit-mediated direction-sensing machinery 'downstream' of G protein-coupled receptor signaling. This study establishes a function for GIT2 in linking chemotaxis and superoxide production in neutrophils and shows that loss of GIT2 in vivo leads to an immunodeficient state.

Topics: Actins; ADP-Ribosylation Factor 1; Animals; Aspergillosis; Cell Cycle Proteins; Chemotactic Factors; Chemotaxis; Complement C5a; Disease Susceptibility; Enzyme Activation; GTP-Binding Protein beta Subunits; GTP-Binding Protein gamma Subunits; GTPase-Activating Proteins; Guanine Nucleotide Exchange Factors; Immunologic Deficiency Syndromes; Intercellular Signaling Peptides and Proteins; Interleukin-8; Lung; Lung Diseases, Fungal; Mice; Mice, Inbred C57BL; Mice, Knockout; Multiprotein Complexes; N-Formylmethionine Leucyl-Phenylalanine; Neutrophils; p21-Activated Kinases; Phosphatidylinositol Phosphates; Phosphoproteins; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins c-akt; rac1 GTP-Binding Protein; Receptors, G-Protein-Coupled; Recombinant Fusion Proteins; Rho Guanine Nucleotide Exchange Factors; Superoxides

Neutrophil-specific granule deficiency (SGD) is a rare, congenital disease characterized by atypical neutrophil structure and function, resulting in recurrent bacterial infections from early infancy. Homozygous recessive mutations in the CCAAT/enhancer-binding protein epsilon (C/EBPepsilon) gene were described in two of five SGD patients, indicating loss of C/EBPepsilon function as the primary genetic defect in this disease. C/EBPepsilon is expressed in murine and human macrophages. Macrophages from the C/EBPepsilon-deficient mice show impaired differentiation, phagocytic activity, and transcription of macrophage-specific genes. To determine if monocyte/macrophage cells are impacted in SGD, we analyzed phenotypic features of peripheral blood (PB) monocytes in a SGD individual lacking functional C/EBPepsilon. Flow cytometric analysis of PB leukocytes revealed aberrant expression of CD45, CD11b, CD14, CD15, and CD16 on cells from the SGD individual. Also, the PB CD14(+) cells from this individual, weakly stained for the monocyte-specific enzyme, nonspecific esterase, and electron microscopic examination, indicated morphologic differences between the SGD cells and those from normal controls. Serum interleukin (IL)-6 levels in the SGD individual during a severe bacterial infection were lower compared with levels in other non-SGD individuals with sepsis. In contrast, serum IL-8 levels were markedly elevated in the SGD individual compared with those of non-SGD individuals in sepsis. PB CD14(+) cells from the SGD individual expressed higher IL-8 mRNA levels compared with normal controls in response to lipopolysaccharide and interferon-gamma. These phenotypic and functional alterations of PB monocytes in the SGD individual suggest that C/EBPepsilon plays a critical role in monocyte/macrophage development of humans and is consistent with observations in the murine system. This study implicates abnormalities in monocytes/macrophages and neutrophils in the onset and development of SGD.

Topics: Animals; Antigens, CD; Carboxylesterase; CCAAT-Enhancer-Binding Proteins; Cytokines; Cytoplasmic Granules; Female; Humans; Immunologic Deficiency Syndromes; Immunophenotyping; Interleukin-8; Mice; Microscopy, Electron; Monocytes; Mutation; Neutrophils; RNA, Messenger