Here we describe a previously unknown form of inherited immunodeficiency revealed by an N-ethyl-N-nitrosourea-induced mutation called elektra. Mice homozygous for this mutation showed enhanced susceptibility to bacterial and viral infection and diminished numbers of T cells and inflammatory monocytes that failed to proliferate after infection and died via the intrinsic apoptotic pathway in response to diverse proliferative stimuli. They also had a greater proportion of T cells poised to replicate DNA, and their T cells expressed a subset of activation markers, suggestive of a semi-activated state.
View Article and Find Full Text PDFHomeostatic control of the immune system involves mechanisms that ensure the self-tolerance, survival and quiescence of hematopoietic-derived cells. In this study, we demonstrate that the GTPase of immunity associated protein (Gimap)5 regulates these processes in lymphocytes and hematopoietic progenitor cells. As a consequence of a recessive N-ethyl-N-nitrosourea-induced germline mutation in the P-loop of Gimap5, lymphopenia, hepatic extramedullary hematopoiesis, weight loss, and intestinal inflammation occur in homozygous mutant mice.
View Article and Find Full Text PDFNull alleles of the gene encoding NEMO (NF-kappaB essential modulator) are lethal in hemizygous mice and men, whereas hypomorphic alleles typically cause a syndrome of immune deficiency and ectodermal dysplasia. Here we describe an allele of Ikbkg in mice that impaired Toll-like receptor signaling, lymph node formation, development of memory and regulatory T cells, and Ig production, but did not cause ectodermal dysplasia. Degradation of IkappaB alpha, which is considered a primary requirement for NEMO-mediated immune signaling, occurred normally in response to Toll-like receptor stimulation, yet ERK phosphorylation and NF-kappaB p65 nuclear translocation were severely impaired.
View Article and Find Full Text PDFSluggish was identified in a population of third generation mice descended from N-ethyl-N-nitrosourea-mutagenized sires. Macrophages from homozygotes exhibited impaired TNF-alpha production in response to all TLR ligands tested and displayed impaired type I IFN production in response to TLR7 and TLR9 stimulations. The phenotype was confined to a critical region on mouse chromosome 18 and then ascribed to a T to A transversion in the acceptor splice site of intron 4 at position 13346 of the Map3k8 gene, resulting in defective splicing.
View Article and Find Full Text PDFThe classical recessive coat color mutation misty (m) arose spontaneously on the DBA/J background and causes generalized hypopigmentation and localized white-spotting in mice, with a lack of pigment on the belly, tail tip, and paws. Here we describe moonlight (mnlt), a second hypopigmentation and white-spotting mutation identified on the C57BL/6J background, which yields a phenotypic copy of m/m coat color traits. We demonstrate that the 2 mutations are allelic.
View Article and Find Full Text PDFHepcidin, a liver-derived protein that restricts enteric iron absorption, is the key regulator of body iron content. Several proteins induce expression of the hepcidin-encoding gene Hamp in response to infection or high levels of iron. However, mechanism(s) of Hamp suppression during iron depletion are poorly understood.
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