Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0409974 (lupus)
 22,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The metabolism of poly(ADP-ribose) in peripheral blood mononuclear (PBM) cells was studied in 13 patients with systemic lupus erythematosus (SLE) and in 12 age and sex matched controls. Poly(ADP-ribose) polymerase activity was measured as the net accumulation of ADP-ribose polymers during the conversion of 32P-NAD to poly(ADP-ribose) in PBM cells in vitro. The control population showed a mean activity of 418 +/- 91(s.d.)pmol ADP-ribose/10 min/10(6) cells. The SLE population was more heterogeneous and showed a lower mean of 225 +/- 147(s.d.)pmol ADP-ribose/10 min/10(6) cells. The mechanism of decreased ADP-ribose polymer accumulation was investigated. Measurements of turnover of the ADP-ribose polymers and its substrate, NAD+, showed that diminished ADP-ribose polymer accumulation in SLE subjects resulted from decreased poly(ADP-ribose) synthesis and not from altered rates of polymer turnover or NAD utilization. Western blot analyses of enzyme protein levels, kinetic studies of poly(ADP-ribose) polymerase activity and analyses of polymer size distribution suggested that the mechanisms of poly(ADP-ribose) synthesis in SLE cells is not altered but that the number of active poly(ADP-ribose) polymerase molecules is reduced.
Lupus 1996 Feb
PMID:Biochemical characterization of ADP-ribose polymer metabolism in SLE. 864 20

Lupus is a chronic inflammatory autoimmune disease influenced by multiple genetic loci including Fas Ligand (FasL) and P2X7 receptor (P2X7R). The Fas/Fas Ligand apoptotic pathway is critical for immune homeostasis and peripheral tolerance. Normal effector T lymphocytes up-regulate the transmembrane tyrosine phosphatase B220 before undergoing apoptosis. Fas-deficient MRL/lpr mice (lpr mutation) exhibit lupus and lymphoproliferative syndromes due to the massive accumulation of B220(+) CD4(-)CD8(-) (DN) T lymphocytes. The precise ontogeny of B220(+) DN T cells is unknown. B220(+) DN T lymphocytes could be derived from effector CD4(+) and CD8(+) T lymphocytes, which have not undergone activation-induced cell death due to inactivation of Fas, or from a special cell lineage. P2X7R is an extracellular ATP-gated cell membrane receptor involved in the release of proinflammatory cytokines and TNFR1/Fas-independent cell death. P2X7R also regulate early signaling events involved in T-cell activation. We show herein that MRL/lpr mice carry a P2X7R allele, which confers a high sensitivity to ATP. However, during aging, the MRL/lpr T-cell population exhibits a drastically reduced sensitivity to ATP- or NAD-mediated stimulation of P2X7R, which parallels the increase in B220(+) DN T-cell numbers in lymphoid organs. Importantly, we found that this B220(+) DN T-cell subpopulation has a defect in P2X7R-mediated responses. The few B220(+) T cells observed in normal MRL(+/+) and C57BL/6 mice are also resistant to ATP or NAD treatment. Unexpectedly, while P2X7R mRNA and proteins are present inside of B220(+) T cells, P2X7R are undetectable on the plasma membrane of these T cells. Our results prompt the conclusion that cell surface expression of B220 strongly correlates with the negative regulation of the P2X7R pathway in T cells.
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PMID:Loss of P2X7 receptor plasma membrane expression and function in pathogenic B220+ double-negative T lymphocytes of autoimmune MRL/lpr mice. 2328 17