This Article Full Text Full Text (PDF) Other Versions of this Article: MCB.00301-07v1 27/21/7355    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Robinson, M. J. Articles by Ley, S. C. Search for Related Content PubMed PubMed Citation Articles by Robinson, M. J. Articles by Ley, S. C.

Next Article 

Molecular and Cellular Biology, November 2007, p. 7355-7364, Vol. 27, No. 21
0270-7306/07/$08.00+0     doi:10.1128/MCB.00301-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Phosphorylation of TPL-2 on Serine 400 Is Essential for Lipopolysaccharide Activation of Extracellular Signal-Regulated Kinase in Macrophages

M. J. Robinson ,^1,, S. Beinke ,^1,, A. Kouroumalis,¹ P. N. Tsichlis,² and S. C. Ley^1*

Division of Immune Cell Biology, National Institute for Medical Research, London, United Kingdom,¹ Molecular Oncology Research Institute, Tufts-New England Medical Center, Boston, Massachusetts²

Received 19 February 2007/ Returned for modification 27 March 2007/ Accepted 10 August 2007

Tumor progression locus 2 (TPL-2) kinase is essential for Toll-like receptor 4 activation of the mitogen-activated protein kinase extracellular signal-regulated kinase (ERK) and for upregulation of the inflammatory cytokine tumor necrosis factor (TNF) in lipopolysaccharide (LPS)-stimulated macrophages. LPS activation of ERK requires TPL-2 release from associated NF-B1 p105, which blocks TPL-2 access to its substrate, the ERK kinase MEK. Here we demonstrate that TPL-2 activity is also regulated independently of p105, since LPS stimulation was still needed for TPL-2-dependent activation of ERK in Nfkb1^–/– macrophages. In wild-type macrophages, LPS induced the rapid phosphorylation of serine (S) 400 in the TPL-2 C-terminal tail. Mutation of this conserved residue to alanine (A) blocked the ability of retrovirally expressed TPL-2 to induce the activation of ERK in LPS-stimulated Nfkb1^–/– macrophages. TPL-2^S400A expression also failed to reconstitute LPS activation of ERK and induction of TNF in Map3k8^–/– macrophages, which lack endogenous TPL-2. Consistently, the S400A mutation was found to block LPS stimulation of TPL-2 MEK kinase activity. Thus, induction of TPL-2 MEK kinase activity by LPS stimulation of macrophages requires TPL-2 phosphorylation on S400, in addition to its release from NF-B1 p105. Oncogenic C-terminal truncations of TPL-2 that remove S400 could promote its transforming potential by eliminating this critical control step.

Published ahead of print on 20 August 2007.

M.J.R. and S.B. contributed equally to this study.

Present address: London Research Institute, Cancer Research UK, 44 Lincoln's Inn Fields, London WC2A 3PX, United Kingdom.

Present address: University of California, San Francisco, Howard Hughes Medical Institute, 513 Parnassus Avenue, San Francisco, CA 94143-0795.

This article has been cited by other articles:

• Rousseau, S., Papoutsopoulou, M., Symons, A., Cook, D., Lucocq, J. M., Prescott, A. R., O'Garra, A., Ley, S. C., Cohen, P. (2008). TPL2-mediated activation of ERK1 and ERK2 regulates the processing of pre-TNF{alpha} in LPS-stimulated macrophages. J. Cell Sci. 121: 149-154 [Abstract] [Full Text]