Erythropoietin induces the association of phosphatidylinositol 3′‐kinase with a tyrosine‐phosphorylated protein complex containing the erythropoietin receptor

Patrick MAYEUX, Isabelle DUSANTER‐FOURT, Odile MULLER, Philippe MAUDUIT, Michèle SABBAH, Brian DRUKER, William VAINCHENKER, Sigmund FISCHER, Catherine LACOMBE, Sylvie GISSELBRECHT

Research output: Contribution to journalArticlepeer-review

63 Scopus citations

Abstract

Stimulation of sensitive cells with erythropoietin results in rapid induction of protein tyrosine phosphorylation. Other than tyrosine phosphorylation of one chain of the erythropoietin receptor, the identities of the remaining tyrosine‐phosphorylated proteins are undefined. In this report, we demonstrate that the stimulation of the erythropoietin‐sensitive human UT7 cells by erythropoietin rapidly resulted in the appearance of phosphatidylinositol 3‐kinase activity in anti‐phosphotyrosine immunoprecipitates. Erythropoietin action was rapid, detectable after as early as 1 min stimulation, transient, returning to control level after 30 min stimulation and was observed using the erythropoietin concentrations able to stimulate the cell proliferation. Anti‐(phosphatidylinositol 3‐kinase) antibodies specifically immunoprecipitated 125I‐erythropoietin bound to its receptor, strongly suggesting that phosphatidylinositol 3‐kinase associated with a protein complex containing the activated erythropoietin receptor. To confirm this result, phosphatidylinositol 3‐kinase was immunoprecipitated from erythropoietin‐stimulated cells using mild conditions followed by Western analysis using anti‐phosphotyrosine antibodies. Five tyrosine phosphorylated proteins were revealed: the cloned chain of the erythropoietin receptor, the regulatory subunit of phosphatidylinositol 3‐kinase and three unidentified proteins of 111, 97 and 64 kDa. None of these tyrosine phosphorylated proteins was detected in anti‐(phosphatidylinositol 3‐kinase) immunoprecipitates from unstimulated cells. Thus, our results show that phosphatidylinositol 3‐kinase associates with a tyrosine‐phosphorylated protein complex containing the activated erythropoietin receptor.

Original languageEnglish (US)
Pages (from-to)821-828
Number of pages8
JournalEuropean Journal of Biochemistry
Volume216
Issue number3
DOIs
StatePublished - Sep 1993

ASJC Scopus subject areas

  • Biochemistry

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