SH2-containing protein tyrosine phosphatase-1 (SHP-1) association with Jak2 in UT-7/Epo cells

Ding Wen Wu, Kenneth C. Stark, Damien Dunnington, Susan B. Dillon, Taolin Yi, Christopher Jones, Louis M. Pelus

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

We have investigated the interaction of the SH2-containing protein tyrosine phosphatase-1 (SHP-1) and Jak2 in an erythropoietin (Epo)-dependent human leukemia cell line, UT-7/Epo, using reciprocal immunoprecipitation and immunoblotting. The Epo-induced kinetics and dose response on phosphorylated Jak2 in anti-SHP-1 precipitates of UT-7/Epo cell lysates were similar to those in direct anti-Jak2 precipitates, suggesting that Jak2 coprecipitated with SHP-1. Furthermore, immunoblotting with anti-Jak2 and anti-SHP-1 antibodies indicated that SHP-1 appeared to be constitutively associated with non-tyrosine-phosphorylated Jak2 in UT-7/Epo cells in the absence of Epo and without phosphorylation of the Epo receptor (EpoR). Competition studies with C-terminal SHP-1 and Jak2 peptides decreased the amounts of SHP-1 and Jak2 detected in immunoprecipitates supporting the specific coprecipitation of SHP-1 and Jak2. In the presence of a recombinant GST-fusion protein containing both the N-terminal and C-terminal SH2 domains of SHP-1, anti-GST precipitated the fusion protein but not cellular Jak2. These studies suggest that SHP-1 and Jak2 are constitutively associated in UT-7/EPO cells. The association is not dependent upon Epo and is not mediated via SHP-1 SH2 binding. Sequential double immunoprecipitation demonstrated that only a small portion of intracellular Jak2 and SHP-1 molecules are constitutively associated. This partial association pattern may allow a more flexible and diverse regulation of Jak2 and SHP-1 activities. Whether Jak2 and SHP-1 are directly associated with each other or are part of a larger complex needs further investigation. (C) 2000 Academic Press.

Original languageEnglish (US)
Pages (from-to)15-24
Number of pages10
JournalBlood Cells, Molecules, and Diseases
Volume26
Issue number1
DOIs
StatePublished - Feb 2000

Keywords

  • Epo-induced signaling
  • Jak2
  • SHP-1
  • UT-7/Epo cells

ASJC Scopus subject areas

  • Molecular Biology
  • Molecular Medicine
  • Hematology

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