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S-nitrosoglutathione modulates CXCR4 and ICOS expression

100%

Yamamoto Y., Pahwa R., Pahwa S.

Cellular and Molecular Biology Letters

2006

tom 11

nr 1

The expression of CXCR4, a membrane protein which is involved in the entry of HIV-1, is down-modulated from the cell surface by Phorbol 12-myristate 13-acetate (PMA) and the Ca+ ionophore, Ionomycin. Inducible co-stimulator (ICOS), which contributes to lymphocyte proliferation, is up-regulated by PMA/Ionomycin. We examined the influence of S-nitrosoglutathione (SNG), an inhibitor of Vacuolar H+-ATPase (V-ATPase), on the expression of CXCR4 and ICOS in PMA/Ionomycin-treated peripheral mononuclear cells (PBMC), and of CXCR4 alone in lymphoid cell lines. In this report, we show that SNG interferes with both effects of PMA/Ionomycin, namely CXCR4 down-regulation and ICOS up-regulation. These studies imply opposing roles of V-ATPase in the regulation of CXCR4 and ICOS. The influence of SNG in modulating the susceptibility of T cells to HIV-1 and on their immune responses needs further investigation.

Degenerate specificity of PDZ domains from RhoA-specific nucleotide exchange factors PDZRhoGEF and LARG

84%

Smietana K., Kasztura M., Paduch M., Derewenda U., Derewenda Z. S., Otlewski J.

Acta Biochimica Polonica

2008

tom 55

nr 2

269-280

PDZ domains are ubiquitous protein–protein interaction modules which bind short, usually carboxyterminal fragments of receptors, other integral or membrane-associated proteins, and occasionally cytosolic proteins. Their role in organizing multiprotein complexes at the cellular membrane is crucial for many signaling pathways, but the rules defining their binding specificity are still poorly understood and do not readily explain the observed diversity of their known binding partners. Two homologous RhoA-specific, multidomain nucleotide exchange factors PDZRhoGEF and LARG contain PDZ domains which show a particularly broad recognition profile, as suggested by the identification of five diverse biological targets. To investigate the molecular roots of this phenomenon, we constructed a phage display library of random carboxyterminal hexapeptides. Peptide variants corresponding to the sequences identified in library selection were synthesized and their affinities for both PDZ domains were measured and compared with those of peptides derived from sequences of natural partners. Based on the analysis of the binding sequences identified for PDZRhoGEF, we propose a sequence for an ‘optimal’ binding partner. Our results support the hypothesis that PDZ–peptide interactions may be best understood when one considers the sum of entropic and dynamic effects for each peptide as a whole entity, rather than preferences for specific residues at a given position.

Ograniczanie wyników

1 Acta Biochimica Polonica

1 Cellular and Molecular Biology Letters

1 Derewenda U.

1 Derewenda Z. S.

1 Kasztura M.

1 Otlewski J.

1 Paduch M.

1 Pahwa R.

1 Pahwa S.

1 Smietana K.

1 Yamamoto Y.

1 2008

1 2006

Wyniki wyszukiwania

S-nitrosoglutathione modulates CXCR4 and ICOS expression

Degenerate specificity of PDZ domains from RhoA-specific nucleotide exchange factors PDZRhoGEF and LARG