AN SH3 DOMAIN IS REQUIRED FOR THE MITOGENIC ACTIVITY OF MICROINJECTED PHOSPHOLIPASE C-GAMMA-1
AN SH3 DOMAIN IS REQUIRED FOR THE MITOGENIC ACTIVITY OF MICROINJECTED PHOSPHOLIPASE C-GAMMA-1
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DOI：
10.1016/0014-5793(94)01453-8
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发表时间：
1995-01-30
期刊：
影响因子：
3.5
通讯作者：
HEIMBROOK, DC
中科院分区：
文献类型：
--
作者：
HUANG, PS;DAVIS, L;HEIMBROOK, DC
磷脂酶活性在分裂细胞中升高。在生长因子刺激下，磷脂酶c - γ (plc - γ)通过SH2结合域与活化的酪氨酸激酶受体结合，导致plc - γ磷酸化并激活其酶活性。这些观察结果表明，plc - γ参与了生长因子促进有丝分裂发生的信号转导途径。与这一假设相一致的是，先前有报道称，将纯化的牛plc - γ微量注射到静止的成纤维细胞中，可启动有丝分裂反应[Smith等人（1989），Proc. Natl.]。[j].科学通报，2016,33(6)。我们用重组大鼠plc - γ蛋白重现了这一结果。然而，令人惊讶的是，plc - γ的催化失活突变体H335Q也引起了完全的有丝分裂反应。通过微量注射PLC-gamma诱导有丝分裂的能力被定位到含有PLC-gamma的SH2和SH3基序的蛋白的“Z”结构域。两个SH2结构域磷酸化酪氨酸结合特性的失活对z结构域肽的有丝分裂活性没有影响。然而，SH3结构域的删除导致活性完全丧失。这些结果表明，plc - γ的有丝分裂特性不需要酶的磷脂酶活性，而是由一种依赖于完整SH3结构域的有丝分裂刺激的新途径介导的。
Phospholipase activity is elevated in dividing cells. In response to growth factor stimulation, phospholipase C-gamma (PLC-gamma) binds to activated tyrosine kinase receptors via SH2 binding domains, resulting in phosphorylation of PLC-gamma and activation of its enzyme activity. These observations suggest that PLC-gamma participates in the signal transduction pathway employed by growth factors to promote mitogenesis. Consistent with this hypothesis, microinjection of purified bovine PLC-gamma into quiescent fibroblasts has been previously reported to initiate a mitogenic response [Smith et al. (1989) Proc. Natl. Acad. Sci. 86, 3659]. We have reproduced this result using recombinant rat PLC-gamma protein. Surprisingly however, a catalytically inactive mutant of PLC-gamma, H335Q, also elicited a full mitogenic response. The capacity to induce mitogenesis by microinjection of PLC-gamma was mapped to the 'Z' domain of the protein, which contains PLC-gamma's SH2 and SH3 motifs. Inactivation of the phosphorylated tyrosine binding properties of both SH2 domains had no effect on the mitogenic activity of the Z-domain peptide. However, deletion of the SH3 domain resulted in a complete loss of activity. These results suggest that PLC-gamma's mitogenic properties do not require the enzyme's phospholipase activity, but are instead mediated by a novel pathway for mitogenic stimulation which is dependent upon an intact SH3 domain.