Critical cytoplasmic domains of the common beta subunit of the human GM-CSF, IL-3 and IL-5 receptors for growth signal transduction and tyrosine phosphorylation.

Abstract

The high‐affinity receptors for human granulocyte‐macrophage colony‐stimulating factor (GM‐CSF), interleukin 3 (IL‐3) and interleukin 5 (IL‐5) are composed of two distinct subunits, alpha and beta c. The alpha subunits are specific for each cytokine, whereas the beta subunit (beta c) is shared by the three receptors and is an essential component of signal transduction. We have made a series of mutant beta c cDNAs that delete various regions of the cytoplasmic domain and examined the function of these mutants by coexpressing them with the alpha subunit of the human GM‐CSF receptor (hGMR) in an IL‐3‐dependent mouse pro‐B cell line BaF3. Two domains in the membrane‐proximal portion of beta c were found to be important for transducing the hGM‐CSF‐mediated growth signals: one domain between Arg456 and Phe487 appears to be essential for proliferation, and the second domain between Val518 and Asp544 enhances the response to GM‐CSF, but is not absolutely required for proliferation. The region between Val518 and Leu626 was responsible for major tyrosine phosphorylation of 95 and 60 kDa proteins. Thus, beta c‐mediated major tyrosine phosphorylation of these proteins was apparently separated from proliferation. However, the beta 517 mutant lacking residues downstream of Val518 transmitted a herbimycin‐sensitive proliferation signal, suggesting that beta 517 still activates a tyrosine kinase(s). We also evaluated the role of the cytoplasmic domain of the GMR alpha subunit and the results suggest that it is involved in the hGM‐CSF‐mediated signal transduction, but is not essential.(ABSTRACT TRUNCATED AT 250 WORDS)

Raf/MAPK and rapamycin-sensitive pathways mediate the anti-apoptotic function of p21Ras in IL-3-dependent hematopoietic cells

“…We previously reported that interleukin 3 (IL-3) and granulocyte macrophage colony stimulating factor (GM-CSF) stimulate multiple signal transduction pathways through the distinct cytoplasmic domains of the shared signaling receptor (bc) Kinoshita et al, 1995b;Miyajima et al, 1993;Sakamaki et al, 1992;Sato et al, 1993). The membrane-proximal short region (a.a. 455 ± 544) mediates c-myc induction (Kinoshita et al, 1995b;Sato et al, 1993) as well as the activation of the Jak2-Stat5 pathway (Quelle et al, 1994) that leads to the induction of several immediate early genes including pim-1 (Mui et al, 1996), oncostatin M (Yoshimura et al, 1996) and cis (for cytokine-inducible SH2-containing protein) (Yoshimura et al, 1995).…”

Activation and Functional Analysis of Janus Kinase 2 in BA/F3 Cells Using the Coumermycin/Gyrase B System

“…The ␣ subunit is specific for each receptor (Gearing et al, 1989), whereas the ␤ subunit (␤c) is shared by all (Kitamura et al, 1991). We reported that IL-3 and GM-CSF stimulate multiple signal transduction pathways through distinct cytoplasmic domains of the ␤c (Sakamaki et al, 1992;Watanabe et al, 1993b). The membrane proximal region, which contains the box1 motif, is involved in the induction of c-myc as well as in cell proliferation.…”

Granulocyte-Macrophage Colony-stimulating Factor-activated Signaling Pathways in Human Neutrophils

“…This, however, is being challenged by recent reports suggesting its involvement in regulating cell growth (22,23). The ␤ subunit, on the other hand, has a long intracytoplasmic tail and plays a major role in transmitting the signal inside the cell (24). Neither subunit has intrinsic enzymatic activity, nor are they known to link to G proteins directly (19).…”