Mitogen-activated protein kinase plays an essential role in the erythropoietin-dependent proliferation of CTLL-2 cells

H. Sakamoto, T. Kitamura, Akihiko Yoshimura

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Erythropoietin (EPO) and its receptor (EPOR) are required for development of erythrocytes. It has been shown that the ectopic expression of EPOR confers EPO-dependent proliferation on an interleukin 3 (IL3)-dependent cell line, Ba/F3, whereas the IL2-dependent T cell line, CTLL-2 expressing the EPOR (T-ER), fails to proliferate in response to EPO. However, the molecular basis of the EPO unresponsiveness in CTLL-2 has not been clarified. We found that the expression level of JAK2 in T-ER cells was much lower than that in Ba/F3 cells. Therefore, we examined the effects of forced expression of JAK2 in T-ER cells. In T-ER transformants expressing JAK2 (T-JER), EPO induced tyrosine phosphorylation of the EPOR, JAK2, and STAT5, and consequently STAT5-responsive genes including bcl-X and cis1 were normally induced. Furthermore, T-JER cells were resistant to apoptosis until at least 72 h after switching from IL2 to EPO. Although T-JER cells could not continuously proliferate in the presence of EPO, additional expression of JAK2 in T-JER (T-JJER) to a level similar to that in Ba/F3 cells supported long term proliferation in response to EPO. JAK2 was equally co-immunoprecipitated with the EPOR among T-JER, T-JJER, and Ba/F3 cells expressing the EPOR (BF-ER). However, EPO-dependent mitogen-activated protein (MAP) kinase activation was observed in T-JJER and BF-ER cells but not in T-JER cells. EPO-dependent long term proliferation of T-JER cells was conferred by expression of the constitutively activated form of MEK1. Our results suggest that MAP kinase activation is, at least in part, an important component for mitotic signal from the EPOR, and CTLL-2 cells probably lack signaling molecule(s) in JAK2 and the Ras-MAP kinase pathway.

Original languageEnglish
Pages (from-to)35857-35862
Number of pages6
JournalJournal of Biological Chemistry
Volume275
Issue number46
DOIs
Publication statusPublished - 2000 Nov 17
Externally publishedYes

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Erythropoietin
Mitogen-Activated Protein Kinases
Erythropoietin Receptors
Interleukin-2
Chemical activation
Cells
Phosphorylation
T-cells
Interleukin-3
Cell Line
Tyrosine
Genes
Apoptosis
Erythrocytes
Molecules
T-Lymphocytes

ASJC Scopus subject areas

  • Biochemistry

Cite this

Mitogen-activated protein kinase plays an essential role in the erythropoietin-dependent proliferation of CTLL-2 cells. / Sakamoto, H.; Kitamura, T.; Yoshimura, Akihiko.

In: Journal of Biological Chemistry, Vol. 275, No. 46, 17.11.2000, p. 35857-35862.

Research output: Contribution to journalArticle

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