Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0021051 (immunodeficiency)
 71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The surface membrane molecule CD5 is expressed on mature T cells and on the B-1a subpopulation of B cells. These CD5 positive B cells express an antibody repertoire with a relatively high frequency of self-reactivity. There is uncertainty about the origins of CD5 B cells and the reasons for this are reviewed. Recent reports which relate to the lineage/selection debate are discussed. For instance, an increase in the frequency of CD5 B cells is a feature of several genetically determined polysystem autoimmune syndromes. In the case of motheaten (me, mev) the pathogenesis of this increase in CD5 B cells is not yet understood, even though the mutation has been mapped to the Hematopoietic cell protein-tyrosine phosphatase (Hcph) gene. Another mutation which affects B cell development, X-linked immunodeficiency (xid), encodes a point mutation in a B cell cytoplasmic tyrosine kinase. Expression of xid in otherwise normal mice causes a lack of CD5 B cells and a shift in the antibody repertoire. Interestingly, expression of both xid and motheaten results in an amelioration of autoantibody production. Evidence is presented that in B cells regulation of expression of CD5 can occur at the level of mRNA and that cross-linking of sIgM can induce the accumulation of CD5 mRNA. The overall concept advanced is that cells expressing natural autoantibodies are triggered via sIgM ligation to become CD5 B cells.
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PMID:Activation of B-cells by sIgM cross-linking induces accumulation of CD5 mRNA. 753 70

Motheaten viable (mev) mice are deficient in the cytosolic protein tyrosine phosphatase, PTP1C, and exhibit severe B cell immunodeficiency and autoantibody production. The role of PTP1C in B cell selection and function was analyzed by breeding immunoglobulin transgenes specific for a defined antigen, hen egg lysozyme, into mev mice. Antigen triggered a greater and more rapid elevation of intracellular calcium in PTP1C-deficient B cells, indicating that this phosphatase negatively regulates immunoglobulin signaling. Elimination of self-reactive B cells carrying this signal-enhancing mutation was triggered during their development by binding a lower valency form of self-antigen than is normally required. These findings establish that activation of distinct repertoire-censoring mechanisms depends on quantitative differences in antigen receptor signaling, whose thresholds are determined by negative regulation through PTP1C.
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PMID:Protein tyrosine phosphatase 1C negatively regulates antigen receptor signaling in B lymphocytes and determines thresholds for negative selection. 760 Feb 99

Homozygosity for the motheaten (me) or viable motheaten (mev) mutations causes severe dysregulation of murine hematopoiesis with the consequent development of both immunodeficiency and systemic autoimmunity. Expression of this phenotype has now been linked to loss-of-function mutations in the gene encoding PTP1C, an intracellular tyrosine phosphatase predominantly expressed in cells of hemopoietic origin. As discussed in this article, the association of PTP1C mutation with the multiple hemopoietic defects found in motheaten mice indicates that this tyrosine phosphatase is critical to normal hematopoiesis and is consistent with the recognized importance of protein tyrosine phosphorylation in modulating the cell signaling pathways governing proliferation and differentiation. The motheaten mouse therefore provides a powerful model of delineating the precise function of PTP1C and thereby elucidating the specific molecular mechanisms whereby this tyrosine phosphatase participates in the control of hemopoietic cell differentiation and function.
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PMID:Identification of PTP1C mutation as the genetic defect in motheaten and viable motheaten mice: a step toward defining the roles of protein tyrosine phosphatases in the regulation of hemopoietic cell differentiation and function. 792 24

Mice homozygous for the autosomal recessive motheaten (me) or the allelic viable motheaten (mev) mutations manifest a unique immunological disease associated with severe immunodeficiency and autoimmunity. Over the past few years, our group has used the motheaten mouse as a model system for elucidating the genetic and cellular events that contribute to expression of normal hematopoietic and immune cell function. To this end, we have sought to identify the gene responsible for the motheaten phenotype. In our initial studies, our general approach involved the use of subtractive hybridization to identify genes that were differentially expressed in the mutant versus control mice and which might thus provide clues as to the primary gene defect. Using this approach, we showed that genes encoding stefin A cysteine proteinase inhibitors are markedly overexpressed in bone marrow cells of me and mev mice compared to bone marrow cells of normal congenic animals. However, the motheaten mutation has been mapped to mouse choromosome 6 while the stefin A gene cluster was localized to mouse chromosome 16. Stefin gene therefore does not represent the primary gene defect. Our second strategy aimed at identifying the primary gene defect underlying the motheaten phenotype was prompted by the recent localization of a protein tyrosine phosphatase gene to human chromosome 12p12-p13, a region containing a large segment of homology with the region on mouse chromosome 6 where the motheaten locus has been mapped. We have shown that abnormal Hcph transcripts are expressed in me and mev bone marrow cells and that the generation of these altered transcripts is due to RNA splicing defects caused by single basepair changes in the Hcph genes of the mutant mice. These mutant mice thus provide a valuable model system for elucidating the biological roles of HCP in vivo and defining the mechanism whereby defective function of a hematopoietic cell phosphatase leads to expression of the motheaten phenotype of severe immunodeficiency and systemic autoimmunity.
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PMID:Molecular basis of the motheaten phenotype. 807 Aug 15

The viable motheaten (mev) mice are characterized by a moth-eaten appearance of the coat, immunodeficiency, autoimmunity, generalized inflammatory disease, paws necroses, and early death. The target of the single point mev mutation is PTP1C, a protein tyrosine phosphatase whose deficient expression in hematopoietic cells should explain all phenotypic features of mev mice, particularly their autoimmune and inflammatory pathologies. In order to evaluate their role in the development of the mev mouse disease, we constructed mevscid congenics to probe the impact of autoimmunity and mevbeige congenics to probe the impact of elastase and cathepsine G neutrophil activities. Both mevscid and mevbeige mice were nearly equivalent to mev mice with regards to moth-eaten appearance, paw necroses and early death. Thus, autoimmunity does neither initiate nor substantially enhance the mev mouse syndrome. Moreover, the beige mutation-linked deficiency of protease activity of neutrophils is unable to significantly reduce the mev mutation-dependent inflammatory pathology.
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PMID:Interactions of the scid or beige mutations with the viable motheaten mutation. 878 12

Increasing numbers of genetic diseases involving bone development and models for these diseases have been identified recently. Analysis of these bone diseases have revealed that regulated action of multiple growth factors and subsequent signal transduction are essential for normal bone formation. In this paper, two murine mutant mice viable motheaten and osteopetrosis are analyzed. Mice with the recessive 'viable motheaten' mutation express a severe immunodeficiency syndrome and bone defects. Mutations at the motheaten locus were shown to be the result of aberrant splicing of the gene encoding hematopoietic cell phosphatase (Hcph). Mice homozygous for the osteopetrosis mutation develop congenital osteopetrosis due to a severe deficiency of osteoclasts. It has been recognized that bone trace element composition analysis helps to define bone-related physiological conditions. We have analyzed bone trace element composition in viable motheaten and osteopetrosis mutant animal models in this study. In order to gain insights into the effects of particular genetic defects on bone trace element composition, inductively coupled plasma atomic emissions spectrometry (ICP-AES) analysis was performed. Marked changes in bone trace element levels were found in limb bones of viable motheaten and osteopetrosis mutant mice. An assessment of these trace element spectrum in the two mutant models with respect to each genetic defects are discussed in this paper.
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PMID:Aberrant regulation of bone trace elements in motheaten and osteopetrosis mutant mice. 959 82