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Cell Surface Levels (cell + surface_level)
Selected AbstractsExpression of CD44 variant isoforms CD44v3 and CD44v6 is increased on T cells from patients with systemic lupus erythematosus and is correlated with disease activityARTHRITIS & RHEUMATISM, Issue 5 2010José C. Crispín Objective To quantify the expression of CD44 and variant isoforms CD44v3 and CD44v6 on T cells from patients with systemic lupus erythematosus (SLE), and to assess correlations of the level of expression of these molecules with disease manifestations. Methods Information on clinical and demographic characteristics was collected, and blood samples were obtained from 72 patients with SLE and 32 healthy control subjects matched to the patients by sex, race, and age. Expression of CD44 and variants CD44v3 and v6 on T cell subsets was determined by flow cytometry, and Pearson's correlations of their expression levels with clinical variables, SLE Disease Activity Index (SLEDAI) scores, and presence of lupus nephritis were determined. Wilcoxon's rank sum tests and conditional multivariable regression analyses were applied to identify differences in the expression of CD44 between patients with SLE and healthy controls. Results Expression of CD44 was higher on CD4+ and CD8+ T cells from SLE patients compared with controls (P , 0.03). Expression of CD44v3 and CD44v6 was also higher on total T cells and CD4+ and CD8+ T cells from SLE patients compared with controls (P , 0.03). Cell surface levels of CD44v3 on total T cells, CD4+ T cells, and CD8+ T cells as well as cell surface expression of CD44v6 on total T cells and CD4+ T cells were correlated with the SLEDAI score (P < 0.05). The presence of lupus nephritis was associated with the expression of CD44v6 on total T cells, CD4+ T cells, and CD4,CD8, T cells (P < 0.05). Positivity for anti,double-stranded DNA antibodies was associated with the expression levels of CD44v6 on T cells (P < 0.05). Conclusion These results indicate that expression levels of CD44v3 and CD44v6 on T cells may represent useful biomarkers of SLE activity. [source] Neuroprotection by donepezil against glutamate excitotoxicity involves stimulation of ,7 nicotinic receptors and internalization of NMDA receptorsBRITISH JOURNAL OF PHARMACOLOGY, Issue 1 2010H Shen BACKGROUND AND PURPOSE Glutamate excitotoxicity may be involved in ischaemic injury to the CNS and some neurodegenerative diseases, such as Alzheimer's disease. Donepezil, an acetylcholinesterase (AChE) inhibitor, exerts neuroprotective effects. Here we demonstrated a novel mechanism underlying the neuroprotection induced by donepezil. EXPERIMENTAL APPROACH Cell damage in primary rat neuron cultures was quantified by lactate dehydrogenase release. Morphological changes associated with neuroprotective effects of nicotine and AChE inhibitors were assessed by immunostaining. Cell surface levels of the glutamate receptor sub-units, NR1 and NR2A, were analyzed using biotinylation. Immunoblot was used to measure protein levels of cleaved caspase-3, total NR1, total NR2A and phosphorylated NR1. Immunoprecipitation was used to measure association of NR1 with the post-synaptic protein, PSD-95. Intracellular Ca2+ concentrations were measured with fura 2-acetoxymethylester. Caspase 3-like activity was measured using enzyme substrate, 7-amino-4-methylcoumarin (AMC)-DEVD. KEY RESULTS Levels of NR1, a core subunit of the NMDA receptor, on the cell surface were significantly reduced by donepezil. In addition, glutamate-mediated Ca2+ entry was significantly attenuated by donepezil. Methyllycaconitine, an inhibitor of ,7 nicotinic acetylcholine receptors (nAChR), inhibited the donepezil-induced attenuation of glutamate-mediated Ca2+ entry. LY294002, a phosphatidyl inositol 3-kinase (PI3K) inhibitor, had no effect on attenuation of glutamate-mediated Ca2+ entry induced by donepezil. CONCLUSIONS AND IMPLICATIONS Decreased glutamate toxicity through down-regulation of NMDA receptors, following stimulation of ,7 nAChRs, could be another mechanism underlying neuroprotection by donepezil, in addition to up-regulating the PI3K-Akt cascade or defensive system. [source] Constitutive association of cell surface CCR5 and CXCR4 in the presence of CD4,JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 4 2004Dr. Jinhai Wang Abstract Chemokine receptors CCR5 and CXCR4 are the major coreceptors of HIV-1 infection and also play fundamental roles in leukocyte trafficking, metastasis, angiogenesis, and embyogenesis. Here, we show that transfection of CCR5 into CXCR4 and CD4 expressing 3T3 cells enhances the cell surface level of CXCR4. In CCR5 high expressing cells, cell surface level of CXCR4 was incompletely modulated in the presence of the CXCR4 ligand CXCL12/SDF-1,. CCR5 was resistant to ligand-dependent modulation with the CCR5 ligand CCL5/RANTES. Confocal laser microscopy revealed that CCR5 was colocalized with CXCR4 on the cell surface. In CD4 expressing CCR5 and CXCR4 double positive NIH 3T3 cells, immunoprecipitation followed by Western blot analysis revealed that CCR5 was associated with CXCR4 and CD4. CXCR4 and CCR5 were not co-immunoprecipitated in cells expressing CCR5 and CXCR4 but without CD4 expression. Compared to NIH 3T3CD4 cells expressing CXCR4, the entry of an HIV-1 X4 isolate (HCF) into NIH 3T3CD4 expressing both CXCR4 and CCR5 was reduced. Our data indicate that chemokine receptors interact with each other, which may modulate chemokine,chemokine receptor interactions and HIV-1 coreceptor functions. Published 2004 Wiley-Liss, Inc. [source] Differential protein expression on the cell surface of colorectal cancer cells associated to tumor metastasisPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 5 2010Jose Luis Luque-García Abstract Progression to metastasis is the critical point in colorectal cancer (CRC) survival. However, the proteome associated to CRC metastasis is very poorly understood at the moment. In this study, we used stable isotope labeling by amino acids in cell culture to compare two CRC cell lines: KM12C and KM12SM, representing poorly versus highly metastatic potential, to find and quantify the differences in protein expression, mostly at the cell surface level. After biotinylation followed by affinity purification, membrane proteins were separated by SDS-PAGE and analyzed using nanoflow LC-ESI-LTQ. A total of 291 membrane and membrane-associated proteins were identified with a p value<0.01, from which 60 proteins were found to be differentially expressed by more than 1.5-fold. We identified a number of cell signaling, CDs, integrins and other cell adhesion molecules (cadherin 17, junction plakoglobin (JUP)) among the most deregulated proteins. They were validated by Western blot, confocal microscopy and flow cytometry analysis. Immunohistochemical analysis of paired tumoral samples confirmed that these differentially expressed proteins were also altered in human tumoral tissues. A good correlation with a major abundance in late tumor stages was observed for JUP and 17-,-hydroxysteroid dehydrogenase type 8 (HSD17B8). Moreover, the combined increase in JUP, occludin and F11 receptor expression together with cadherin 17 expression could suggest a reversion to a more epithelial phenotype in highly metastatic cells. Relevant changes were observed also at the metabolic level in the pentose phosphate pathway and several amino acid transporters. In summary, the identified proteins provide us with a better understanding of the events involved in liver colonization and CRC metastasis. [source] | ||||||||||