Tài liệu Báo cáo khoa học: Myristoylation of the dual-specificity phosphatase c-JUN N-terminal kinase

Myristoylation of the dual-specificity phosphatase c-JUN

N-terminal kinase (JNK) stimulatory phosphatase 1 is

necessary for its activation of JNK signaling and apoptosis

Ulla Schwertassek1

, Deirdre A. Buckley1,*, Chong-Feng Xu2

, Andrew J. Lindsay3

,

Mary W. McCaffrey3

, Thomas A. Neubert2 and Nicholas K. Tonks1

1 Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA

2 Kimmel Center for Biology and Medicine at the Skirball Institute and Department of Pharmacology, New York University School of

Medicine, NY, USA

3 Molecular Cell Biology Laboratory, Department of Biochemistry, Biosciences Institute, University College Cork, Ireland

Introduction

Mitogen-activated protein kinase (MAPK) signaling

pathways are critical regulators of cellular responses to

environmental stimuli, such as growth signals and

stress, that modulate cell behavior, such as proliferation,

differentiation or cell death [1–4]. All MAPK pathways

consist of a central three-tiered core signaling module in

which MAPK kinase kinases phosphorylate MAPK kin￾ases on Ser⁄Thr residues with concomitant activation.

MAPK kinases are dual-specificity kinases, which, upon

activation, phosphorylate both the Tyr and Thr residue

Keywords

apoptosis; JNK; JSP1; myristoylation;

phosphatase

Correspondence

N. K. Tonks, Cold Spring Harbor Laboratory,

1 Bungtown Road, Cold Spring Harbor, NY

11724-2208, USA

Fax: 001 516 367 6812

Tel: 001 516 367 8846

E-mail: [email protected]

*Present address

Cell Biology Laboratory, Department of

Biochemistry, Biosciences Institute,

University College Cork, Ireland

(Received 16 February 2010, revised 19

March 2010, accepted 23 March 2010)

doi:10.1111/j.1742-4658.2010.07661.x

Activation of the c-JUN N-terminal kinase (JNK) pathway is implicated in

a number of important physiological processes, from embryonic morpho￾genesis to cell survival and apoptosis. JNK stimulatory phosphatase 1

(JSP1) is a member of the dual-specificity phosphatase subfamily of protein

tyrosine phosphatases. In contrast to other dual-specificity phosphatases

that catalyze the inactivation of mitogen-activated protein kinases, expres￾sion of JSP1 activates JNK-mediated signaling. JSP1 and its relative

DUSP15 are unique among members of the protein tyrosine phosphatase

family in that they contain a potential myristoylation site at the N-terminus

(MGNGMXK). In this study, we investigated whether JSP1 was myristoy￾lated and examined the functional consequences of myristoylation. Using

mass spectrometry, we showed that wild-type JSP1, but not a JSP1 mutant

in which Gly2 was mutated to Ala (JSP1-G2A), was myristoylated in cells.

Although JSP1 maintained intrinsic phosphatase activity in the absence of

myristoylation, the subcellular localization of the enzyme was altered.

Compared with the wild type, the ability of nonmyristoylated JSP1 to

induce JNK activation and phosphorylation of the transcription factor

c-JUN was attenuated. Upon expression of wild-type JSP1, a subpopula￾tion of cells, with the highest levels of the phosphatase, was induced to

float off the dish and undergo apoptosis. In contrast, cells expressing simi￾lar levels of JSP1-G2A remained attached, further highlighting that the

myristoylation mutant was functionally compromised.

Abbreviations

DSP, dual-specificity phosphatase; ERK, extracellular signal-regulated kinase; JKAP, c-JUN N-terminal kinase pathway-associated

phosphatase; JNK, c-JUN N-terminal kinase; JSP, c-JUN N-terminal kinase stimulatory phosphatase; JSP1-CS, inactive mutant of JSP1

(active site Cys88 changed to Ser); JSP1-G2A, JSP1 mutant (myristoylation site Gly2 changed to Ala); JSP1-wt, wild-type JSP1; MAPK,

mitogen-activated protein kinase; PARP, poly (ADP-ribose) polymerase; PTP, protein tyrosine phosphatase.

FEBS Journal 277 (2010) 2463–2473 ª 2010 The Authors Journal compilation ª 2010 FEBS 2463