Premium
Serum alleviates the requirement of the granulocyte‐macrophage colony‐stimulating factor (GM‐CSF)‐induced Ras activation for proliferation of BaF3 cells
Author(s) -
Sakamakia Kazuhiro,
Yonehara Shin
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)01024-2
Subject(s) - microbiology and biotechnology , granulocyte macrophage colony stimulating factor , kinase , phosphorylation , signal transduction , biology , growth factor , receptor , in vitro , biochemistry
Deletion analysis of the β subunit of the human granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) receptor previously defined two cytoplasmic regions required for distinct signaling. The membrane‐proximal region is responsible for induction of c‐ myc and pim‐1 , and is indispensable for GM‐CSF‐dependent proliferation of mouse BaF3 transfectants. The distal region is required for activation of Ras, Raf‐1, MAP kinase and p70 S6 kinase as well as induction of c‐ fos and c‐ jun , but is dispensable for GM‐CSF‐dependent proliferation of transfectants under normal culture conditions containing serum. Here we show that signals induced by the distal region of the β subunit are also required for proliferation. GM‐CSF supported proliferation of BaF3 transfectants expressing the normal β subunit, even in serum‐free medium. However, in the absence of serum, GM‐CSF did not support proliferation of BaF3 transfectants that have the β deletion mutants lacking the distal region. Serum‐induced activation of Ras, phosphorylation of MAP kinase and expression of c‐ fos in parental BaF3 cells and antisense oligonucleotide against c‐ raf blocked DNA synthesis of BaF3 cells. These results indicate that proliferation of BaF3 cells requires signals induced by the proximal as well as the distal region of the β subunit of the GM‐CSF receptor, and that serum alleviates the requirement of signals induced by the distal region.