Phosphorylation of Protein-tyrosine Phosphatase PTP-1B on Identical Sites Suggests Activation of a Common Signaling Pathway during Mitosis and Stress Response in Mammalian Cells

doi:10.1074/jbc.272.5.2957

Phosphorylation of Protein-tyrosine Phosphatase PTP-1B on Identical Sites Suggests Activation of a Common Signaling Pathway during Mitosis and Stress Response in Mammalian Cells*

From the^‡ Cancer Biology Program and Division of Hematology-Oncology, Department of Medicine, Beth Israel Hospital, Boston, Massachusetts 02215 and the
^¶ Howard Hughes Medical Institute and University of Massachusetts Medical School, Worcester, Massachusetts 01605

** Recipient of a Junior Faculty Research Award from the American Cancer Society. To whom correspondence should be addressed:
Cancer Biology Program & Division of Hematology-Oncology, Dept. of Medicine, Beth Israel Hospital, HIM 1043, 330 Brookline Ave., Boston, MA 02215
. Tel.: 617-667-2823; Fax: 617-667-0610; E-mail: bneel{at}bih.harvard.edu.

↵§ Present address: Dana Farber Cancer Institute, 44 Binney St., Boston, MA 02115.

Abstract

PTP-1B is a widely expressed non-transmembrane tyrosine-specific phosphatase. Previous studies indicated that, at mitosis, PTP-1B undergoes phosphorylation on two sites, ³⁵²Ser-Pro-Leu-Asn and ³⁸⁶Ser-Pro-Ala-Lys. Although the Ser-386 site can be phosphorylated by Cyclin B/Cdc2 in vitro, the kinase for the Ser-352 site is unknown. We have found that these phosphorylation events are not unique to normal mitosis. Instead, treatment with many, but not all, stress stimuli, in particular osmotic shock and certain phosphatase and protein synthesis inhibitors, leads to phosphorylation of PTP-1B. Tryptic phosphopeptide and mutant analysis reveals that, as in mitosis, stress-induced PTP-1B phosphorylation involves both Ser-352 and Ser-386. Activation of the proline-directed kinases Erk1/2, JNKs, and p38 was neither necessary nor sufficient for stress-induced PTP-1B phosphorylation. Our data suggest the existence of a novel mitogen-activated protein kinase pathway in mammalian cells, which is activated at mitosis and in response to osmotic shock and other stresses and results in PTP-1B phosphorylation. This pathway may be similar to the recently described Spc1/Sty1 pathway in Schizosaccharomyces pombe.

Footnotes

↵^∥ Investigator of the Howard Hughes Medical Institute.
↵* This work was supported in part by National Institutes of Health Grant R01 CA49152 (to B. G. N.). The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

PTK

protein-tyrosine kinase

PTP

protein-tyrosine phosphatase

PBS

phosphate-buffered saline

TNFα

tumor necrosis factor α

PMSF

phenylmethylsulfonyl fluoride

DAPI

4,6-diamidino-2-phenylindole

IL

interleukin

MAP

mitogen-activated protein

MEK

MAP kinase

HA

hemagglutinin

PAGE

polyacrylamide gel electrophoresis

GST

glutathione S-transferase.
↵² J. V. Frangioni, V. I. Shifrin, and B. G. Neel, unpublished data.
↵³ V. I. Shifrin, R. J. Davis, and B. G. Neel, unpublished data.
- Received October 9, 1996.
- Revision received November 21, 1996.