A FUNCTIONAL DOMAIN IN THE HEAVY-CHAIN OF SCATTER FACTOR HEPATOCYTE GROWTH-FACTOR BINDS THE C-MET RECEPTOR AND INDUCES CELL-DISSOCIATION BUT NOT MITOGENESIS
A FUNCTIONAL DOMAIN IN THE HEAVY-CHAIN OF SCATTER FACTOR HEPATOCYTE GROWTH-FACTOR BINDS THE C-MET RECEPTOR AND INDUCES CELL-DISSOCIATION BUT NOT MITOGENESIS
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DOI：
10.1073/pnas.89.23.11574
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发表时间：
1992-12-01
影响因子：
11.1
通讯作者：
BIRCHMEIER, W
中科院分区：
文献类型：
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作者：
HARTMANN, G;NALDINI, L;BIRCHMEIER, W
我们最近发现，散射因子（SF），一个细胞运动因子与一个多模块的结构，是相同的肝细胞生长因子（HGF），一个强大的有丝分裂的各种类型的细胞。SF/HGF是c-Met受体酪氨酸激酶的配体。在这里，我们使用的瞬时表达的自然发生的和在体外诱变的SF/HGF的cDNA描绘的蛋白质结构域所需的生物活性和结合的c-Met受体。(i)由重链和轻链之间的蛋白酶切割位点（Arg-494 -> Gln）的破坏产生的单链SF/HGF在很大程度上是无活性的，表明蛋白水解切割对于获得生物活性构象是必需的。(ii)SF/HGF剪接变体编码的蛋白质在第一个kringle结构域中具有5个氨基酸的缺失，其活性与野生型分子一样高。(iii)单独表达的轻链（具有丝氨酸蛋白酶同源性）在所有试验中均无活性。(iv)单独的重链以及自然发生的刺突变体组成的N末端和前两个kringle域绑定的c-Met受体，刺激酪氨酸自磷酸化，并诱导散射的上皮细胞，但不是有丝分裂。这些数据表明，SF/HGF的N末端/前两个kringle区中的功能结构域足以与Met受体结合，并且这导致参与运动性反应的下游信号级联的激活。然而，完整的SF/HGF蛋白似乎是有丝分裂活性所必需的。
We recently found that scatter factor (SF), a cell motility factor with a multimodular structure, is identical to hepatocyte growth factor (HGF), a potent mitogen of various cell types. SF/HGF is the ligand of the c-Met receptor tyrosine kinase. Here we used transient expression of naturally occurring and in vitro mutagenized cDNAs of SF/HGF to delineate the protein domains necessary for biological activity and binding to the c-Met receptor. (i) A single-chain SF/HGF resulting from the destruction of the protease cleavage site between heavy and light chain (Arg-494 --> Gln) was largely inactive, indicating that proteolytic cleavage is essential for acquisition of the biologically active conformation. (ii) A SF/HGF splice variant encoding a protein with a 5-amino acid deletion in the first kringle domain was as highly active as the wild-type molecule. (iii) The separately expressed light chain (with serine protease homology) was inactive in all assays tested. (iv) The separate heavy chain as well as a naturally occurring spike variant consisting of the N terminus and the first two kringle domains bound the c-Met receptor, stimulated tyrosine autophosphorylation, and induced scattering of epithelial cells but not mitogenesis. These data indicate that a functional domain in the N terminus/first two kringle regions of SF/HGF is sufficient for binding to the Met receptor and that this leads to the activation of the downstream signal cascade involved in the motility response. However, the complete SF/HGF protein seems to be required for mitogenic activity.