Abstract
The MEK-1/2 kinase TPL-2 is critical for Toll-like receptor activation of the ERK-1/2 MAP kinase pathway during inflammatory responses, but it can transform cells following C-terminal truncation. IκB kinase (IKK) complex phosphorylation of the TPL-2 C terminus regulates full-length TPL-2 activation of ERK-1/2 by a mechanism that has remained obscure. Here, we show that TPL-2 Ser-400 phosphorylation by IKK and TPL-2 Ser-443 autophosphorylation cooperated to trigger TPL-2 association with 14-3-3. Recruitment of 14-3-3 to the phosphorylated C terminus stimulated TPL-2 MEK-1 kinase activity, which was essential for TPL-2 activation of ERK-1/2. The binding of 14-3-3 to TPL-2 was also indispensible for lipopolysaccharide-induced production of tumor necrosis factor by macrophages, which is regulated by TPL-2 independently of ERK-1/2 activation. Our data identify a key step in the activation of TPL-2 signaling and provide a mechanistic insight into how C-terminal deletion triggers the oncogenic potential of TPL-2 by rendering its kinase activity independent of 14-3-3 binding.
Original language | English |
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Pages (from-to) | E2394-E2403 |
Number of pages | 10 |
Journal | Proceedings of the National Academy of Sciences of the United States of America |
Volume | 111 |
Issue number | 23 |
Early online date | 27 May 2014 |
DOIs | |
Publication status | Published - 10 Jun 2014 |
Keywords
- 14-3-3 Proteins/genetics
- Animals
- Cells, Cultured
- Enzyme Activation
- HEK293 Cells
- Humans
- I-kappa B Kinase/metabolism
- Immunoblotting
- Lipopolysaccharides/pharmacology
- MAP Kinase Kinase Kinases/genetics
- MAP Kinase Signaling System
- Macrophages/drug effects
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mitogen-Activated Protein Kinase 1/metabolism
- Mitogen-Activated Protein Kinase 3/metabolism
- NF-kappa B p50 Subunit/genetics
- Phosphorylation
- Protein Binding
- Proto-Oncogene Proteins/genetics
- Serine/genetics
- Toll-Like Receptors/metabolism
- Tumor Necrosis Factor-alpha/metabolism
- inflammation
- NF-κB
- MAP3K8