Effects of Overexpression of PTP36, a Putative Protein Tyrosine Phosphatase, on Cell Adhesion, Cell Growth, and Cytoskeletons in HeLa Cells

doi:10.1074/jbc.274.18.12905

Effects of Overexpression of PTP36, a Putative Protein Tyrosine Phosphatase, on Cell Adhesion, Cell Growth, and Cytoskeletons in HeLa Cells*

From the Department of Oncology, Biomedical Research Center, Osaka University Medical School, Suita, Osaka 565-0871, the^§School of Allied Health Science, Faculty of Medicine, Osaka University, Suita, Osaka 565-0871, and the ^¶Department of Immunology, Saga Medical School, Nabeshima, Saga 849, Japan

Abstract

Non-receptor-type putative protein tyrosine phosphatase-36 (PTP36), also known as PTPD2/Pez, possesses a domain homologous to the N-terminal half of band 4.1 protein. To gain insight into the biological function of PTP36, we established a HeLa cell line, HtTA/P36-9, in which the overexpression of PTP36 was inducible. PTP36 expressed in HeLa cells was enriched in the cytoskeleton near the plasma membrane. There was little endogenous PTP36 detectable in uninduced HtTA/P36-9 cells or in the parental HeLa cells. Upon induction of PTP36 overexpression, HtTA/P36-9 cells spread less well, grew more slowly, and adhered to the extracellular matrix proteins less well than uninduced cells. Moreover, decreases in the actin stress fibers and the number of focal adhesions were observed. The tyrosine phosphorylation of the focal adhesion kinase induced by lysophosphatidic acid was suppressed in the HtTA/P36-9 cells overexpressing PTP36. These results indicate that PTP36 affects cytoskeletons, cell adhesion, and cell growth, thus suggesting that PTP36 is involved in their regulatory processes.

Footnotes

↵* This work was supported in part by a grant-in-aid for scientific research from the Ministry of Education, Science, and Culture, Japan and by the Japan Research Foundation for Clinical Pharmacology.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.
↵‡ To whom correspondence should be addressed: Biomedical Research Center, Osaka University Medical School C6, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan. Tel.: 81-6-6879-3982; Fax: 81-6-6879-3989; E-mail:mogata{at}ongene.med.osaka-u.ac.jp.
↵2 M. Ogata and T. Hamaoka, unpublished observations.
Abbreviations:

PTP

protein tyrosine phosphatase

FAK

focal adhesion kinase

LPA

lysophosphatidic acid

HA

hemagglutinin

HtTA

HeLa cells expressing a tetracycline-controlled transactivator

DMEM

Dulbecco’s modified Eagle’s medium

PBS

phosphate-buffered saline

BSA

bovine serum albumin

GFP

green fluorescent protein

MES

4-morpholineethanesulfonic acid

PIPES

1,4-piperazinediethanesulfonic acid

PTPMEG

cytosolic megakaryocyte protein tyrosine phosphatase
- Received December 9, 1998.
- Revision received January 27, 1999.
The American Society for Biochemistry and Molecular Biology, Inc.