Genome-Wide Expression Profiling and Mutagenesis Studies Reveal that Lipopolysaccharide Responsiveness Appears To Be Absolutely Dependent on TLR4 and MD-2 Expression and Is Dependent upon Intermolecular Ionic Interactions
Meng, Jianmin ; Gong, Mei ; Björkbacka, Harry LU
and Golenbock, Douglas T.
(2011)
In Journal of Immunology
187(7).
p.3683-3693
- Abstract
- Lipid A (a hexaacylated 1,4' bisphosphate) is a potent immune stimulant for TLR4/MD-2. Upon lipid A ligation, the TLR4/MD-2 complex dimerizes and initiates signal transduction. Historically, studies also suggested the existence of TLR4/MD-2-independent LPS signaling. In this article, we define the role of TLR4 and MD-2 in LPS signaling by using genome-wide expression profiling in TLR4- and MD-2-deficient macrophages after stimulation with peptidoglycan-free LPS and synthetic Escherichia coli lipid A. Of the 1396 genes significantly induced or repressed by any one of the treatments in the wild-type macrophages, none was present in the TLR4-or MD-2-deficient macrophages, confirming that the TLR4/MD-2 complex is the only receptor for... (More)
- Lipid A (a hexaacylated 1,4' bisphosphate) is a potent immune stimulant for TLR4/MD-2. Upon lipid A ligation, the TLR4/MD-2 complex dimerizes and initiates signal transduction. Historically, studies also suggested the existence of TLR4/MD-2-independent LPS signaling. In this article, we define the role of TLR4 and MD-2 in LPS signaling by using genome-wide expression profiling in TLR4- and MD-2-deficient macrophages after stimulation with peptidoglycan-free LPS and synthetic Escherichia coli lipid A. Of the 1396 genes significantly induced or repressed by any one of the treatments in the wild-type macrophages, none was present in the TLR4-or MD-2-deficient macrophages, confirming that the TLR4/MD-2 complex is the only receptor for endotoxin and that both are required for responses to LPS. Using a molecular genetics approach, we investigated the mechanism of TLR4/MD-2 activation by combining the known crystal structure of TLR4/MD-2 with computer modeling. According to our murine TLR4/MD-2-activation model, the two phosphates on lipid A were predicted to interact extensively with the two positively charged patches on mouse TLR4. When either positive patch was abolished by mutagenesis into Ala, the responses to LPS and lipid A were nearly abrogated. However, the MyD88-dependent and -independent pathways were impaired to the same extent, indicating that the adjuvant activity of monophosphorylated lipid A most likely arises from its decreased potential to induce an active receptor complex and not more downstream signaling events. Hence, we concluded that ionic interactions between lipid A and TLR4 are essential for optimal LPS receptor activation. The Journal of Immunology, 2011, 187: 3683-3693. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/2272024
- author
- Meng, Jianmin
; Gong, Mei
; Björkbacka, Harry
LU
and Golenbock, Douglas T.
- organization
- publishing date
- 2011
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Journal of Immunology
- volume
- 187
- issue
- 7
- pages
- 3683 - 3693
- publisher
- American Association of Immunologists
- external identifiers
-
- wos:000295036400027
- scopus:80053487700
- pmid:21865549
- ISSN
- 1550-6606
- DOI
- 10.4049/jimmunol.1101397
- language
- English
- LU publication?
- yes
- id
- 20404883-d1b3-4b9d-82ff-3601c4dc98d6 (old id 2272024)
- date added to LUP
- 2016-04-01 15:04:43
- date last changed
- 2022-02-19 22:26:16
@article{20404883-d1b3-4b9d-82ff-3601c4dc98d6,
abstract = {{Lipid A (a hexaacylated 1,4' bisphosphate) is a potent immune stimulant for TLR4/MD-2. Upon lipid A ligation, the TLR4/MD-2 complex dimerizes and initiates signal transduction. Historically, studies also suggested the existence of TLR4/MD-2-independent LPS signaling. In this article, we define the role of TLR4 and MD-2 in LPS signaling by using genome-wide expression profiling in TLR4- and MD-2-deficient macrophages after stimulation with peptidoglycan-free LPS and synthetic Escherichia coli lipid A. Of the 1396 genes significantly induced or repressed by any one of the treatments in the wild-type macrophages, none was present in the TLR4-or MD-2-deficient macrophages, confirming that the TLR4/MD-2 complex is the only receptor for endotoxin and that both are required for responses to LPS. Using a molecular genetics approach, we investigated the mechanism of TLR4/MD-2 activation by combining the known crystal structure of TLR4/MD-2 with computer modeling. According to our murine TLR4/MD-2-activation model, the two phosphates on lipid A were predicted to interact extensively with the two positively charged patches on mouse TLR4. When either positive patch was abolished by mutagenesis into Ala, the responses to LPS and lipid A were nearly abrogated. However, the MyD88-dependent and -independent pathways were impaired to the same extent, indicating that the adjuvant activity of monophosphorylated lipid A most likely arises from its decreased potential to induce an active receptor complex and not more downstream signaling events. Hence, we concluded that ionic interactions between lipid A and TLR4 are essential for optimal LPS receptor activation. The Journal of Immunology, 2011, 187: 3683-3693.}},
author = {{Meng, Jianmin and Gong, Mei and Björkbacka, Harry and Golenbock, Douglas T.}},
issn = {{1550-6606}},
language = {{eng}},
number = {{7}},
pages = {{3683--3693}},
publisher = {{American Association of Immunologists}},
series = {{Journal of Immunology}},
title = {{Genome-Wide Expression Profiling and Mutagenesis Studies Reveal that Lipopolysaccharide Responsiveness Appears To Be Absolutely Dependent on TLR4 and MD-2 Expression and Is Dependent upon Intermolecular Ionic Interactions}},
url = {{http://dx.doi.org/10.4049/jimmunol.1101397}},
doi = {{10.4049/jimmunol.1101397}},
volume = {{187}},
year = {{2011}},
}