Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents

This Article Full Text Full Text (PDF, 261K) PPT slides of all figures Alert me when this article is cited Citation Map Services Email this article Similar articles in this journal Similar articles in PubMed Alert me to new content in the JEM Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Schromm, A. B. Articles by Golenbock, D. T. Search for Related Content PubMed PubMed Citation Articles by Schromm, A. B. Articles by Golenbock, D. T. Pubmed/NCBI databases Gene GEO Profiles HomoloGene Protein UniGene Compound via MeSH Substance via MeSH Social Bookmarking                            What's this?

Original Article

Andra B. Schromm^a,b, Egil Lien^c, Philipp Henneke^a, Jesse C. Chow^d, Atsutoshi Yoshimura^e, Holger Heine^b, Eicke Latz^a, Brian G. Monks^a, David A. Schwartz^f, Kensuke Miyake^g, and Douglas T. Golenbock^a

^a Evans Biomedical Research Center, Boston University School of Medicine, Boston, MA 02118
^b Research Center Borstel, 23845 Borstel, Germany
^c Institute of Cancer Research and Molecular Biology, Norwegian University of Science and Technology, 7489 Trondheim, Norway
^d Eisai Research Institute, Andover, MA 01810
^e Nagasaki University School of Dentistry, Nagasaki 852-8588, Japan
^f Duke University Medical Center, Durham, NC 27710
^g Saga Medical School, Saga 849-8501, Japan
Rm. 615, Evans Biomedical Research Center, Boston University School of Medicine, 650 Albany St., Boston, MA 02118.617-414-5280617-414-7965

douglas.golenbock{at}bmc.org

Somatic cell mutagenesis is a powerful tool for characterizing receptor systems. We reported previously two complementation groups of mutant cell lines derived from CD14-transfected Chinese hamster ovary–K1 fibroblasts defective in responses to bacterial endotoxin. Both classes of mutants expressed a normal gene product for Toll-like receptor (TLR)4, and fully responded to stimulation by tumor necrosis factor (TNF)- or interleukin (IL)-1β. We identified the lesion in one of the complementation groups in the gene for MD-2, a putative TLR4 coreceptor. The nonresponder phenotype of this mutant was reversed by transfection with MD-2. Cloning of MD-2 from the nonresponder cell line revealed a point mutation in a highly conserved region resulting in a C95Y amino acid exchange. Both forms of MD-2 colocalized with TLR4 on the cell surface after transfection, but only the wild-type cDNA reverted the lipopolysaccharide (LPS) nonresponder phenotype. Furthermore, soluble MD-2, but not soluble MD-2_C95Y, functioned to enable LPS responses in cells that expressed TLR4. Thus, MD-2 is a required component of the LPS signaling complex and can function as a soluble receptor for cells that do not otherwise express it. We hypothesize that MD-2 conformationally affects the extracellular domain of TLR4, perhaps resulting in a change in affinity for LPS or functioning as a portion of the true ligand for TLR4.

Key Words: sepsis • signal transduction • Toll-like receptors • Gram-negative bacteria • lipopolysaccharide

© 2001 The Rockefeller University Press

CiteULike    Complore    Connotea    Del.icio.us    Digg    Facebook    Reddit    Technorati    Twitter    What's this?

Home | Help | Feedback | Subscriptions | Archive | Search

TABLE OF CONTENTS