Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024141 (systemic lupus erythematosus)
 44,322 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Purine nucleoside phosphorylase (PNP) deficiency is a rare inherited disease accounting for approximately 4% of patients with severe combined immunodeficiency. Thirty-three patients have been reported. PNP-deficient patients suffer from recurrent infections, usually beginning in the first year of life. Two thirds of patients have evidence of neurologic disorders. Findings range from spasticity to developmental delay, to mental retardation. One third of patients develop autoimmune disease. The most common manifestation of this is autoimmune hemolytic anemia. Idiopathic thrombocytopenic purpura and systemic lupus erythematosis have also been reported. Patients usually present with infections but approximately one fourth have come to medical care initially for neurological problems. In PNP deficiency, T- and B-cell immunity are affected. T-cell function may be profoundly deficient, may be normal at birth and then decrease with time, or may fluctuate repeatedly between low and normal. B-cell function can be normal but is deficient in approximately one third of patients. PNP protein is a trimer of approximately 90,000 daltons. It is found in most tissues of the body but is at highest levels in lymphoid tissues. This tissue distribution explains why the lymphoid system is predominantly affected in PNP deficiency. Many mechanisms have been proposed to explain the metabolic toxicity in PNP deficiency. The elevated dGTP found in PNP deficiency is thought to inhibit ribonucleotide reductase and, thus, impede cell division. Depressed GTP levels may correlate with neurologic dysfunction. The gene for PNP has been cloned; it is located on the long arm of chromosome 14. Studies of a mutant PNP gene isolated from one patient showed that a point mutation resulting in an amino acid substitution was responsible for PNP deficiency. PNP deficiency has a grave prognosis. No patient has reached the third decade of life. Twenty-nine of the 33 reported patients have died from their disease. Prenatal diagnosis is currently available. Many different therapies have been utilized for PNP deficiency including bone marrow transplantation, red cell transfusions, and supplementation of the diet with purines and pyrimidines. None of these therapies has been consistently successful. In light of the poor prognosis for PNP deficiency, bone marrow transplantation should be considered for all patients. In the future, improved forms of therapy such as gene therapy may become available.
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PMID:Purine nucleoside phosphorylase deficiency. 193 Oct 7

An autoantibody reactive with a conserved sequence of 28 S rRNA (anti-28 S) was identified in serum from a patient with systemic lupus erythematosus. Anti-28 S protected a unique 59-nucleotide fragment synthesized in vitro against RNase T1 digestion. RNA sequence analysis revealed that it corresponded to residues 1944-2002 in human 28 S rRNA and 1767-1825 in mouse 28 S rRNA. These sequences are identical and highly conserved throughout all known eukaryotic 28 S rRNAs. In addition, this fragment is homologous to residues 1052-1110 of Escherichia coli 23 S rRNA that lies within the GTP hydrolysis center of the 50 S ribosomal subunit. Anti-28 S and its Fab fragments strongly inhibited poly(U)-directed polyphenylalanine synthesis, but had no effect on ribosomal peptidyltransferase activity. This effect resulted from inhibition of the binding of elongation factors EF-1 alpha and EF-2 to ribosomes and of the associated GTP hydrolysis. The inhibitory effect was almost completely suppressed by preincubation of anti-28 S with 28 S rRNA or in vitro synthesized RNA fragments containing the immunoreactive region. These results show that the immunoreactive conserved region of 28 S rRNA participates in the interaction of ribosomes with the two elongation factors in protein synthesis.
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PMID:A human autoantibody specific for a unique conserved region of 28 S ribosomal RNA inhibits the interaction of elongation factors 1 alpha and 2 with ribosomes. 198 69

The growth inhibitory mechanisms of mizoribine, an immunosuppressive imidazole nucleoside used clinically to inhibit rejection reactions after renal transplantation and in the treatment of systemic lupus erythematosus and rheumatoid arthritis, were studied in human and murine cells. We found that (a) human cells were 20- to 60-fold more resistant than murine cells to both mizoribine and its aglycone, (b) adenine phosphoribosyltransferase (APRT)-deficient human cells were resistant to aglycone but not to mizoribine, (c) hypoxanthine phosphoribosyltransferase (HPRT)-deficient human cells were at least 100-fold more sensitive to both mizoribine and aglycone, and (d) the decrease in intracellular GTP broadly paralleled the cytotoxicity in each case. Therefore, data obtained from studies using non-human tissues should be interpreted carefully before clinical application. Results indicate that the growth inhibitory effect of the aglycone but not of mizoribine is mediated by APRT, and depletion of guanine nucleotides is responsible for the effects of both drugs. Our data also suggest that the drugs may reduce mutant HPRT-deficient somatic cells in vivo, and may cause enhanced adverse reactions in HPRT-deficient individuals. The drug may have altered effects in patients receiving other purine or pyrimidine analogs.
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PMID:Differential cytotoxic effects of mizoribine and its aglycone on human and murine cells and on normal and enzyme-deficient human cells. 757 67

To address the molecular mechanism underlying the functional defects of peripheral T cells in systemic lupus erythematosus (SLE), we focused on early signaling events. We demonstrated that protein expression of the TCR zeta chain was significantly decreased in peripheral T cells from patients with SLE compared to normal controls and patients with systemic sclerosis (SSc). Among those patients showing decreased TCR zeta chain expression, we found two patients with pronounced TCR zeta chain abnormalities, including an aberrant 14 kDa form in one and only trace expression in the other. RT-PCR, SSCP and subsequent cloning of the transcripts revealed that bases 468503, corresponding to exon 7, were deleted in both patients. Since exon 7 spans the GTP/GDP binding site and N-terminal tyrosine in the third ITAM domain of TCR zeta chain, the transcript lacking exon 7 may be responsible for altered signal transduction via TCR in these SLE patients.
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PMID:TCR zeta chain lacking exon 7 in two patients with systemic lupus erythematosus. 970 Oct 29

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease of unknown aetiology. Although it has been reported that T cells might be responsible for the pathogenesis of SLE, it remains unclear whether immune aberrations of SLE T cells are the primary event in this pathological process. We have recently reported that tyrosine phosphorylation and expression of the T cell receptor zeta chain (TCR zeta) was significantly decreased in SLE T cells and that two SLE patients exhibited a 36 bp, exon 7 deletion of the TCR zeta mRNA. To investigate further common mutations in TCR zeta mRNA among SLE patients, mRNA was isolated from the peripheral blood T cells of two normal controls, two systemic sclerosis (SSc) patients, and eight SLE patients. TCR zeta cDNA was amplified by RT-PCR. Five out of the eight SLE patients exhibited abnormal migration patterns of the TCR zeta cDNA in PCR single stranded conformational polymorphism analysis. PCR products were ligated into pUC18 and five clones obtained were sequenced. Analysis of the nucleotide sequences revealed that all of the five pUC18 clones from the normal controls and SSc patients had the normal nucleotide sequence, whereas all eight SLE patients had mutations in TCR zeta cDNA accompanied by predicted amino acid substitutions. Mutations found in six of these patients corresponded to those of the third immunoreceptor tyrosine-based activation motif (ITAM) domain or the GTP/GDP binding site in TCR zetaThus, these mutations in TCR zeta mRNA could be responsible for the decreased expression of the TCR zeta protein in SLE T cells.
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PMID:Mutations in T cell receptor zeta chain mRNA of peripheral T cells from systemic lupus erythematosus patients. 980 20

High-frequency single nucleotide polymorphism (SNP) alleles are useful in mapping genes responsible for disease susceptibility. Functionally, Fcgamma receptors (FcgammaR) have been implicated in autoimmune disease, and the gene encoding the signaling element for several FcgammaR, Fc-epsilon-receptor gamma-chain (FcepsilonRIgamma), has several SNPs in the immunoreceptor tyrosine activation motif (ITAM) recorded in GenBank. Direct sequencing of the FcepsilonRIgamma coding region found potentially polymorphic sites in the 5'-->3' direction in control donors, which were not confirmed in the reverse direction (n = 66), and further exploration of 80 SLE patients revealed no non-synonymous SNPs. One normal donor was heterozygous for a non-synonymous SNP at nt 38 which changed the fifth codon from valine (GTG) to methionine (ATG). Although the EST databases suggest candidate SNPs, insertions and deletions, these appear to be artifacts, most probably due to secondary structure. The coding region of FcepsilonRIgamma shows a remarkable absence of nucleotide diversity. Either as yet unidentified regulatory elements of FcepsilonRIgamma or other genes in the region of human chromosome 1q23 are likely to be systemic lupus erythematosus disease susceptibility and severity genes.
Lupus 2002
PMID:Conservation of FcepsilonRI gamma chain coding region in normals and in SLE patients. 1189 18

B cell receptor (BCR) signaling plays a critical role in B cell tolerance and activation. Here, we show that mice with B cell-specific ablation of both Cbl and Cbl-b (Cbl-/-Cblb-/-) manifested systemic lupus erythematosus (SLE)-like autoimmune disease. The Cbl double deficiency resulted in a substantial increase in marginal zone (MZ) and B1 B cells. The mutant B cells were not hyperresponsive in terms of proliferation and antibody production upon BCR stimulation; however, B cell anergy to protein antigen appeared to be impaired. Concomitantly, BCR-proximal signaling, including tyrosine phosphorylation of Syk tyrosine kinase, Phospholipase C-gamma2 (PLC-gamma2), and Rho-family GTP-GDP exchange factor Vav, and Ca2+ mobilization were enhanced, whereas tyrosine phosphorylation of adaptor protein BLNK was substantially attenuated in the mutant B cells. These results suggested that the loss of coordination between these pathways was responsible for the impaired B cell tolerance induction. Thus, Cbl proteins control B cell-intrinsic checkpoint of immune tolerance, possibly through coordinating multiple BCR-proximal signaling pathways during anergy induction.
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PMID:Control of the B cell-intrinsic tolerance programs by ubiquitin ligases Cbl and Cbl-b. 1749 44

Genetic and environmental factors are believed to influence development of systemic lupus erythematosus (SLE). Endogenous retroviruses (ERV) correspond to the integrated proviral form of infectious retroviruses, which are trapped within the genome due to mutations. ERV represent a key molecular link between the host genome and infectious viral particles. ERV-encoded proteins are recognized by antiviral immune responses and become targets of autoreactivity. Alternatively, ERV protein may influence cellular processes and the life cycle of infectious viruses. As examples, the HRES-1 human ERV encodes a 28-kDa nuclear autoantigen and a 24-kDa small GTP-ase, termed HRES-1/Rab4. HRES-1/p28 is a nuclear autoantigen recognized by cross-reactive antiviral antibodies, while HRES-1/Rab4 regulates surface expression of CD4 and the transferrin receptor (TFR) through endosome recycling. Expression of HRES-1/Rab4 is induced by the tat gene of HIV-1, which in turn down-regulates expression of CD4 and susceptibility to re-infection by HIV-1. CD4 and the TFR play essential roles in formation of the immunological synapse (IS) during normal T-cell activation by a cognate MHC class II peptide complex. The key intracellular transducer of T-cell activation, Lck, is brought to the IS via binding to CD4. T-cell receptorzeta (TCRzeta) chain binds to the TFR. Abnormal T-cell responses in SLE have been associated with reduced lck and TCRzeta chain levels. HRES-1 is centrally located on chromosome 1 at q42 relative to lupus-linked microsatellite markers and polymorphic HRES-1 alleles have been linked to the development of SLE. 1q42 is one of the three most common fragile sites in the human genome, and is inducible by DNA demethylation, a known mechanism of retroviral gene activation. Molecular mimicry and immunomodulation by a ERV, such as HRES-1, may contribute to self-reactivity and abnormal T and B-cell functions in SLE.
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PMID:Molecular mimicry and immunomodulation by the HRES-1 endogenous retrovirus in SLE. 1843 9

Statins have been successfully used in patients with hypercholesterolemia and cardiovascular diseases, but there is increasing evidence that they exert effects by much exceeding the lowering of cholesterol levels. Statins have antiatherosclerotic, antiinflammatory, antioxidant, immunomodulatory and antithrombotic effects. These "pleiotropic" effects stem from their inhibition of prenylation of the small GTP-binding proteins Ras and Rho, and to the disruption, or depletion, of cholesterol rich membrane micro-domains (membrane rafts). Through these pathways statins modulate immune responses by altering cytokine levels and by affecting the function of cells involved in both innate and adaptive responses. Anti-inflammatory and immunosuppressory properties of statins provide the rationale for their potential application in conditions in which the inflammation and immune response represent key pathogenic mechanisms, such as antiphospholipid syndrome, rheumatoid arthritis and systemic lupus erythematosus. Reduction of atherosclerosis progression in autoimmunity is also a very important effect. Statins pathways of action in systemic autoimmune diseases, and their potential therapeutic use are discussed in this review. The inhibition of mevalonate pathway by statins impairs modification of Ras and Rho GTPases, which play key roles in signaling pathways related to tumor formation, metastasis and cell death. There is experimental and clinical evidence that statins may improve the therapeutic outcome of anticancer drugs. Thus, this review will also discuss recent insights into the molecular mechanisms underlying the anticancer effects of statins and their assessment as promising candidates for inclusion into current therapeutic regimens for the treatment of malignant diseases.
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PMID:To cardiovascular disease and beyond: new therapeutic perspectives of statins in autoimmune diseases and cancer. 2225 Jun 52

In this study, the complete mitochondrial genome of the Tibetan wolf (Canis lupus laniger) was sequenced using blood samples obtained from a wild female Tibetan wolf captured from Lhasa in Tibet, China. Qinghai-Tibet Plateau, with an average elevation above 3500 m, is the highest plateau in the world. Sequence analysis showed that its structure is in accordance with other Canidae species, but GTG is used as the start codon in ND4L gene which is different from many canide animals.
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PMID:The complete mitochondrial genome sequence of the Tibetan wolf (Canis lupus laniger). 2443 45


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