Joint study on regulation of cell profferation by cytokines

在这个合作项目中，我们正在研究在生长因子介导的哺乳动物细胞增殖和分化中诱导DNA复制、基因表达和其他各种细胞反应的机制。今年，我们获得了以下结果：1)我们分离到了裂解酵母Hsk1激酶的一个可能的调节亚基。在几个编码Hsk1相互作用分子的庞氏链霉菌克隆中，Him1(H__-SK1 I_-相互作用m_olecule 1)与Hsk1形成复合体，刺激其激酶活性，并被Hsk1特异性磷酸化。Hm~(1+)是裂解酵母细胞存活所必需的，其转录受细胞周期调控，在G1/S交界处达到最大值，但不受CDC10^+的控制。2)我们还分离到一个新的人类cDNAH37，编码一个与huCDC7相互作用的分子。当h37和hucdc7与hucdc7在cos 7细胞或昆虫细胞中共表达时，形成一个复合体，该复合体的形成激活hucdc激酶Re…。在hucdc和H37的广泛磷酸化中有更多的硫磺。这表明H37是huCDC激酶的一个调节亚单位。微量注射抗H37蛋白抗体抑制了原代成纤维细胞的DNA合成，表明H37-huCDC7的功能是S阶段启动所必需的。3)我们用竞争性聚合酶链式反应的方法定位了人类5q区GM-CSF/IL-3基因的复制起点。我们的初步结果表明，在基因间隔区的可诱导DNaseI超敏部位附近存在一个活跃的复制起点。4)我们已经定位了GM-CSF受体β链细胞质区域的酪氨酸残基，该区域的磷酸化是DNA复制、诱导早期反应基因、防止细胞凋亡等过程所必需的。5)我们已经证明，仅JAK2的二聚化可以诱导c-myc的诱导，6)我们分离到新的克隆，这些克隆是通过细胞因子刺激突变型GM-CSF受体而诱导的，这些受体能够特异性地促进增殖。6)给人GM-CSF给人GM-CSF受体转基因小鼠刺激小鼠的骨髓生成以及红细胞和巨核细胞生成。它还影响了转基因小鼠的自然杀伤细胞的发育。较少

In this collaborative project, we are studying on the mechanisms of induction of DNA replication, gene expression and other various cellular responses in growth factor-mediated proliferation and differentiation of mammalian cells.This year, we have obtained the following results.1) We have isolated a putative regulatory subunit for fission yeast Hsk1 kinase. Among several S.pombe clones encoding Hsk1-interacting molecules, Him1 (H__-sk1 i__-nteracting m__-olecule 1) forms a complex with Hsk1, stimulates its kinase activity and is specifically phosphorylated by Hsk1. him1^+ is essential for viability of fission yeast cells and its transcription is cell cycle-regulated, reaching maximum at the G1/S boundary, although it is not under the control of cdc10^+.2) We have also isolated a novel human cDNA,H37, encoding a huCdc7-interacting molecule. H37 and huCdc7, when coexpressed with huCdc7 in COS7 cells or in insect cells, forms a complex and the complex formation activates huCdc kinase, re … More sulting in extensive phosphorylation of both huCdc and H37. This indicates that H37 is a regulatory subunit for huCdc kinase. Microinjection of antibodies against H37 protein inhibited DNA synthesis in primary fibroblast cells, indicating that the function of H37-huCdc7 is required for S phase initiation.3) We have mapped replication origins in the GM-CSF/IL-3 locus of the human 5q region by using the competitive PCR method. Our preliminary results indicate the presence of an active replication origin near the inducible DNaseI-hypersensitive site within the intergenic region.4) We have mapped tyrosine residues of the cytoplasmic region of beta-chain of GM-CSF receptore whose phosphorylation is required for DNA replication, induction of early response genes, prevention of apoptosis, and so on.5) We have shown that dimerization of Jak2 alone can induce induction of c-myc, STAT5 activation and cytokine-independent proliferation.6) We have isolated novel clones whish are induced by cytokine stimulation of mutant GM-CSF receptors capable specifically of promoting proliferaton.6) Administration of human GM-CSF to human GM-CSF receptor transgenic mice stimulated myelopoiesis as well as erythropoiesis and megakaryopoiesis in mice. it also affected the development of natural killer cells in the transgenic mice. Less