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The p38? mitogen-activated protein kinase possesses an intrinsic autophosphorylation activity, generated by a short region composed of the ?-G helix and MAPK insert.

ABSTRACT: Protein kinases are regulated by a large number of mechanisms that vary from one kinase to another. However, a fundamental activation mechanism shared by all protein kinases is phosphorylation of a conserved activation loop threonine residue. This is achieved in many cases via autophosphorylation. The mechanism and structural basis for autophosphorylation are not clear and are in fact enigmatic because this phosphorylation occurs when the kinase is in its inactive conformation. Unlike most protein kinases, MAP kinases are not commonly activated by autophosphorylation but rather by MEK-dependent phosphorylation. Here we show that p38?, a p38 isoform that is almost identical to p38?, is exceptional and spontaneously autoactivates by autophosphorylation. We identified a 13-residue-long region composed of part of the ?G-helix and the MAPK insert that triggers the intrinsic autophosphorylation activity of p38?. When inserted into p38?, this fragment renders it spontaneously active in vitro and in mammalian cells. We further found that an interaction between the N terminus and a particular region of the C-terminal extension suppresses the intrinsic autophosphorylation of p38? in mammalian cells. Thus, this study identified the structural motif responsible for the unique autophosphorylation capability of p38? and the motif inhibiting this activity in living cells. It shows that the MAPK insert and C-terminal extension, structural motifs that are unique to MAPKs, play a critical role in controlling autophosphorylation.

SUBMITTER: Beenstock J

PROVIDER: S-EPMC4156038 | biostudies-literature | 2014 Aug

REPOSITORIES: biostudies-literature

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The p38β mitogen-activated protein kinase possesses an intrinsic autophosphorylation activity, generated by a short region composed of the α-G helix and MAPK insert.

Beenstock Jonah J Ben-Yehuda Sheer S Melamed Dganit D Admon Arie A Livnah Oded O Ahn Natalie G NG Engelberg David D

The Journal of biological chemistry 20140708 34

Protein kinases are regulated by a large number of mechanisms that vary from one kinase to another. However, a fundamental activation mechanism shared by all protein kinases is phosphorylation of a conserved activation loop threonine residue. This is achieved in many cases via autophosphorylation. The mechanism and structural basis for autophosphorylation are not clear and are in fact enigmatic because this phosphorylation occurs when the kinase is in its inactive conformation. Unlike most prote ...[more]

PMID: 25006254

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Project description:AimsSome asthma patients remain symptomatic despite using high doses of inhaled corticosteroids (ICS). We used alveolar macrophages to identify individual patients with insensitivity to corticosteroids and to evaluate the anti-inflammatory effects of a p38 mitogen-activated protein kinase (MAPK) inhibitor combined with a corticosteroid on these cells.MethodsAlveolar macrophages from 27 asthma patients (classified according to the Global Initiative for Asthma (GINA) treatment stage. Six GINA1, 10 GINA2 and 11 GINA3/4) were stimulated with lipoploysaccharide (LPS) (1 ?g ml(-1)). The effects of dexamethasone (dex 1-1000 nm), the p38 MAPK inhibitor 1-(5-tert-butyl-2-p-tolyl-2Hpyrazol-3-yl)-3(4-(2-morpholin-4-yl-ethoxy)naphthalen-1-yl)urea (BIRB-796 1-1000 nm) and both drugs combined at all concentrations on supernatant TNF?, IL-6 and CXCL-8 concentrations were analyzed by ELISA. Dose-sparing and efficacy enhancing effects of combination treatment were determined.ResultsDexamethasone reduced LPS-induced TNF?, IL-6 and CXCL-8 in all groups, but maximum inhibition was significantly reduced for GINA3/4 compared with GINA2 and GINA1 (P < 0.01). A subgroup of corticosteroid insensitive patients with a reduced effect of dexamethasone on cytokine secretion were identified. BIRB-796 in combination with dexamethasone significantly increased cytokine inhibition compared with either drug alone (P < 0.001) in all groups. This effect was greater in corticosteroid insensitive compared with sensitive patients. There were significant synergistic dose-sparing effects (P < 0.05) for the combination treatment on inhibition of TNF?, IL-6 and CXCL-8 in all groups. There was also significant efficacy enhancing benefits (P < 0.05) on TNF? and IL-6.Conclusionsp38 MAPK inhibitors synergistically enhance efficacy of corticosteroids in macrophages from asthma patients. This effect is greater in corticosteroid insensitive asthma patients, suggesting that this class of drug should be targeted to this patient phenotype.

Dataset Information

The p38? mitogen-activated protein kinase possesses an intrinsic autophosphorylation activity, generated by a short region composed of the ?-G helix and MAPK insert.

Publications

The p38β mitogen-activated protein kinase possesses an intrinsic autophosphorylation activity, generated by a short region composed of the α-G helix and MAPK insert.

Similar Datasets

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