| Autor: |
Qureshi N; Department of Basic Medical Science, School of Medicine and Shock/Trauma Research Center, University of Missouri, Kansas City, MO 64108, USA. qureshi@umkc.edu, Perera PY, Shen J, Zhang G, Lenschat A, Splitter G, Morrison DC, Vogel SN |
| Jazyk: |
angličtina |
| Zdroj: |
Journal of immunology (Baltimore, Md. : 1950) [J Immunol] 2003 Aug 01; Vol. 171 (3), pp. 1515-25. |
| DOI: |
10.4049/jimmunol.171.3.1515 |
| Abstrakt: |
We have developed a novel LPS probe using a highly purified and homogenous preparation of [(3)H] Escherichia coli LPS from the deep rough mutant, which contains a covalently linked, photoactivable 4-p-(azidosalicylamido)-butylamine group. This cross-linker was used to identify the LPS-binding proteins in membranes of the murine-macrophage-like cell line RAW 264.7. The alpha-subunit (PSMA1 C2, 29.5 kDa) and the beta-subunit (PSMB4 N3, 24.36 kDa) of the 20S proteasome complex were identified as LPS-binding proteins. This is the first report demonstrating LPS binding to enzymes such as the proteasome subunits. Functionally, LPS enhanced the chymotrypsin-like activity of the proteasome to degrade synthetic peptides in vitro and, conversely, the proteasome inhibitor lactacystin completely blocked the LPS-induced proteasome's chymotrypsin activity as well as macrophage TNF-alpha secretion and the expression of multiple inflammatory mediator genes. Lactacystin also completely blocked the LPS-induced expression of Toll-like receptor 2 mRNA. In addition, lactacystin dysregulated mitogen-activated protein kinase phosphorylation in LPS-stimulated macrophages, but failed to inhibit IL-1 receptor-associated kinase-1 activity. Importantly, lactacystin also prevented LPS-induced shock in mice. These data strongly suggest that the proteasome complex regulates the LPS-induced signal transduction and that it may be an important therapeutic target in Gram-negative sepsis. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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