G-CSF-induced proliferation and differentiation of neutrophils

血液中的中性粒细胞是由干细胞通过各种中间细胞产生的。中性粒细胞祖细胞的增殖和分化受粒细胞集落刺激因子（G-CSF）的特异性调控。在此之前，我们已经分离到了G-CSF和G-CSF受体的cDNA，并阐明了它们的结构。通过将克隆的G-CSF受体cDNA导入正常情况下不表达G-CSF受体的小鼠骨髓前体细胞，我们发现了G-CSF受体中增殖和分化的两个不同功能域。分化信号包括特异性基因诱导的髓过氧化物酶或白细胞弹性酶，它们通常在中性粒细胞中表达。G-CSF受体的细胞质区含有4个酪氨酸残基，这些残基在G-CSF结合后被磷酸化。这些酪氨酸残基的突变分析表明，每个酪氨酸残基在介导中性粒细胞分化的信号中具有不同的作用。我们发现，当G-CSF与受体结合时，Jak1和Jak2激酶以及STAT3转录因子被特异性激活。利用STAT3的显性阴性形式，我们可以证明STAT3参与了g - csf诱导的分化信号，特别是在g - csf诱导的中性粒细胞形态学改变中。细胞的发育和分化往往由含有锌指结构域的转录因子决定。我们已经分离出一种新的髓系锌指蛋白（MZF）。

Neutrophils in blood are generated from stem cells through various intermediate cells. Proliferation and differentiation of the progenitor cells of neutrophils are specifically regulated by granulocyte colony-stimulating factor (G-CSF). Previously, we have isolated cDNA for G-CSF and G-CSF receptor, and elucidated their structure. By introducing the cloned G-CSF receptor cDNA in mouse myeloid precursor cells which normally do not express the G-CSF receptor, we identified two distinct functional domains in the G-CSF receptor for proliferation and differentiation. The differentiation signal included the specific gene induction of myeloperoxidase or leukocyte elastase which are normally expressed in neutrophils. The cytoplasmic region of the G-CSF receptor contains 4 tyrosine residues, which are phosphorylated upon binding of G-CSF.Mutational analysis of these tyrosine residues indicated that each tyrosine residue has a distinct role to transduce the signals which lead to the neutrophil differentation. We showed that Jak1 and Jak2 kinases as well as STAT3 transcription factor are specifically activated upon binding of G-CSF to the receptor. Using the dominant-negative form of STAT3, we could show that STAT3 is involved in the G-CSF-induced differentiation signal, in particular, in the G-CSF-induced morphological changes of the neutrophilic granulocytes. Development and differentiation of cell are often determined by transcription factors containing zinc-finger domains. We have isolated a novel form of myeloid zinc-finger protein (MZF).