Pro-inflammatory Cytokines and Environmental Stress Cause p38 Mitogen-activated Protein Kinase Activation by Dual Phosphorylation on Tyrosine and Threonine

doi:10.1074/jbc.270.13.7420

Pro-inflammatory Cytokines and Environmental Stress Cause p38 Mitogen-activated Protein Kinase Activation by Dual Phosphorylation on Tyrosine and Threonine (*)

From the (1)Program in Molecular Medicine, Department of Biochemistry and Molecular Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, the
(2)Howard Hughes Medical Institute, Worcester, Massachusetts 01605, and the
(3)Department of Immunology, The Scripps Research Institute, La Jolla, California 92037

^§ Investigator of the Howard Hughes Medical Institute. To whom correspondence should be addressed:
Howard Hughes Medical Institute, Program in Molecular Medicine, University of Massachusetts Medical School, 373 Plantation St., Worcester, MA 01605
.

Abstract

Protein kinases activated by dual phosphorylation on Tyr and Thr (MAP kinases) can be grouped into two major classes: ERK and JNK. The ERK group regulates multiple targets in response to growth factors via a Ras-dependent mechanism. In contrast, JNK activates the transcription factor c-Jun in response to pro-inflammatory cytokines and exposure of cells to several forms of environmental stress. Recently, a novel mammalian protein kinase (p38) that shares sequence similarity with mitogen-activated protein (MAP) kinases was identified. Here, we demonstrate that p38, like JNK, is activated by treatment of cells with pro-inflammatory cytokines and environmental stress. The mechanism of p38 activation is mediated by dual phosphorylation on Thr-180 and Tyr-182. Immunofluorescence microscopy demonstrated that p38 MAP kinase is present in both the nucleus and cytoplasm of activated cells. Together, these data establish that p38 is a member of the mammalian MAP kinase group.

Footnotes

↵* This work was supported by Grant CA58396 from the National Cancer Institute. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

MAP

mitogen-activated protein

ATF2

activating transcription factor 2

cPLA₂

cytoplasmic phospholipase A₂

EGF

epidermal growth factor

EGF-R

EGF receptor

GST

glutathione S-transferase

JNK

c-Jun NH₂-terminal kinase

LPS

lipopolysaccharide

UV

ultraviolet

PAGE

polyacrylamide gel electrophoresis.
↵² Control experiments demonstrated that JNK, but not p38 MAP kinase, bound to the activation domain of c-Jun.
↵³ A caveat that must be placed on the interpretation of the immunofluorescence experiments is that the images obtained represent the cellular distribution of over-expressed p38 MAP kinase. The distribution of endogenous p38 MAP kinase may be different.
- Received November 29, 1994.
- Revision received January 27, 1995.