Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C1862200 (RHE)
 1,093 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Membrane permeable N-ethylmaleimide (NEM) and (2-aminoethyl)methanethiosulfonatehydrobromide (MTSEA) inhibited the rat brain Na(+)-Ca(2+) exchanger RBE-2 (NCX1.5) expressed in HEK 293 cells in a dose dependent manner. 50% inhibition was obtained at 1 mm MTSEA and 1.65 mm NEM. External application of membrane impermeable [2-(trimethylammonium) ethyl]methanethiosulfonatebromide (MTSET) and sodium(2-sulfonatoethyl)methanethiosulfonate (MTSES) did not inhibit the transport activity in whole cells. Following reconstitution, however, of RBE-2 transfected cell proteins into proteoliposomes, external application of MTSET and MTSES led to a decrease in transport activity to 42.7 (S.D. = 9.1) and 51% (S.D. = 10.14), respectively. Similar results were obtained also when the rat heart isoform RHE-1 (NCX1.1) or the rat brain isoform RBE-1 (NCX1.4) was expressed. NEM and MTSEA inhibited Na(+) gradient-dependent Ca(2+) uptake also in HEK 293 cells expressing RBE-2/C14A/C20S/ C122S/C780S (numbering corresponds to RBE-2), a mutant in which all putative extracellular cysteines were exchanged. To study the accessibility of different cysteines to covalent modification, surface biotinylation of cells expressing the wild type exchanger and its mutants was carried out using 3-(N-maleimidylpropionyl)biocytin. Surface biotinylation revealed immunoreactive protein derived from the wild type Na(+)-Ca(2+) exchanger only if the transfected cells were exposed to the reducing agent Tris(2-carboxyethyl)phosphine. No reduction was needed when the single cysteine mutants of RBE-2, C14A, C20S, and C780S, were expressed. Treatment of the cells expressing these mutants with MTSET before biotinylation, led to a decrease in the amount of exchanger protein that was revealed. No immunoreactive protein was detected when the quadruple mutant RBE-2, C14A/C20S/C122S/C780S, was biotinylated, suggesting that no additional cysteines are accessible directly from the extracellular face of the membrane. Permeabilizing the cells expressing RBE-2/C14A/C20S/ C122S/C780S with streptolysin O resulted in biotinylation of the exchanger protein. Its amount decreased if exposure to NEM preceded streptolysin O treatment. Our results suggest that Na(+)-Ca(2+) exchange activity is inhibited by covalent modification with sulfhydryl reagents of cysteine residues that are accessible from the cytoplasmic face of the membrane.
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PMID:The transport activity of the Na+-Ca2+ exchanger NCX1 expressed in HEK 293 cells is sensitive to covalent modification of intracellular cysteine residues by sulfhydryl reagents. 1113 12

Cyclosporin A (CsA) treatment of HEK 293 cells expressing the rat heart RHE-1 (NCX1.1, EMBL accession number ) or the rat brain RBE-2 (NCX1.5, GenBank(TM) accession number ) Na(+)-Ca(2+) exchanger inhibited their transport activity in a concentration-dependent manner. The inhibition was detectable at 2 microm CsA, and exposure of the cells to 20 microm CsA resulted in a decrease of the Na(+)-dependent Ca(2+) uptake to about 20% relative to that of untreated cells. Determination of the surface expression of the exchanger protein revealed a parallel concentration-dependent reduction in the amount of the immunoreactive protein. No reduction was detected in the amount of total immunoreactive exchanger protein in CsA-treated cells relative to untreated ones. Among the different drugs tested, only PSC833, an analog of cyclosporin D, mimicked the effects of CsA. Exposure of the transfected cells to the chemically related cyclosporin D and macrolide drugs (FK506 or rapamycin) had no effect on the transport activity or the surface expression of the Na(+)-Ca(2+) exchanger. Co-expression of the human multidrug transporter P-glycoprotein (of which both drugs are modulators) with the cloned Na(+)-Ca(2+) exchanger revealed that transport activity and surface expression of each transporter in the co-transfected system were similar to those of each transporter alone in both the presence and absence of CsA or PSC833. CsA and PSC833 inhibited the surface expression of the NCX1 protein but did not alter the surface expression of P-glycoprotein. Unlike some P-glycoprotein endoplasmic reticulum-retained mutants (Loo, T. W., and Clarke, D. M. (1997) J. Biol. Chem. 272, 709-712), CsA did not rescue RBE-2/F913-->Stop, an endoplasmic reticulum-retained function-competent mutant of the Na(+)-Ca(2+) exchanger (Kasir, J., Ren, X., Furman, I., and Rahamimoff, H. (1999) J. Biol. Chem. 274, 24873-24880) and did not induce its kinesis to the surface membrane, further demonstrating molecular differences between P-glycoprotein and NCX1 mutants for interaction with CsA.
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PMID:Transport activity and surface expression of the Na+-Ca2+ exchanger NCX1 are inhibited by the immunosuppressive agent cyclosporin A and by the nonimmunosuppressive agent PSC833. 1170 Mar 17

Lannea microcarpa (Anacardiaceae) is a tropical tree used in African folk medicine and commercial dermopharmaceutical formulations. Fractionation and analysis of its polar extract allowed the identification of 4'-methoxy-myricetin 3-O-alpha-L-rhamnopyranoside, myricetin 3-O-alpha-L-rhamnopyranoside, myricetin 3-O-beta-D-glucopyranoside, vitexin, isovitexin, gallic acid and epi-catechin, as the major constituents. In-vivo assay (the croton oil ear test in mice) showed that the extract had significant anti-inflammatory effect (ID50 = 900 microg cm(-2)) but ten times lower than that of indometacin (ID50 = 93 microg cm(-2)), the non-steroidal anti-inflammatory drug used as reference. Cytotoxicity and cutaneous irritation of the extract and its constituents were investigated. The crude extract and its major components did not affect cell viability in-vitro either in three different cultures (J774. A1, WEHI-164 and HEK-293) of cells grown in monolayers or in the reconstituted human epidermis (RHE, 3D model), nor did they cause release of pro-inflammatory mediators (IL-1alpha) or histomorphological modification of RHE.
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PMID:An extract of Lannea microcarpa: composition, activity and evaluation of cutaneous irritation in cell cultures and reconstituted human epidermis. 1680 59