Toll-like receptors (TLRs) signalling and expression pattern.
Toll is a Drosophila gene essential for ontogenesis and antimicrobial resistance. Several homologues of Toll have been identified and cloned in vertebrates, namely Toll-like receptors (TLRs). TLRs are structurally characterized by a cytoplasmic Toll/interleukin-1R (TIR) domain and by extracellular leucine rich repeats. TLRs characterized so far activate the MyD88/IRAK signalling cascade which activates NF-kappaB transcription factor. Genetic, gene transfer, and dominant negative approaches have involved TLR family members (TLR2 and TLR4) in distinct bacterial components for recognition and signalling. However, very little information is available regarding other TLRs. Here we propose to classify TLRs based on their expression pattern, in ubiquitous (TLR1), restricted (TLR2, 4, 5) and specific (TLR3) TLRs. Differential expression and regulation as well as distinct, though overlapping, ligand recognition patterns may underlie the existence of a such a large, seemingly redundant, TLR family.
Muzio
M
M
Department of Immunology and Cell Biology, Istituto di Ricerche Farmacologiche Mario Negri, Milano, Italy. marta.muzio@PHARMACIA.COM
Mantovani
A
A
D015152:Blotting, Northern; D002478:Cells, Cultured; D029721:Drosophila Proteins; D006801:Humans; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*; D051194:Toll-Like Receptor 1; D051195:Toll-Like Receptor 2; D051196:Toll-Like Receptor 3; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors
D029721:Drosophila Proteins; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; C495342:TLR2 protein, human; C495344:TLR3 protein, human; C495345:TLR4 protein, human; D051194:Toll-Like Receptor 1; D051195:Toll-Like Receptor 2; D051196:Toll-Like Receptor 3; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors