Role of Src family tyrosine kinases in the down-regulation of epidermal growth factor signaling in PC12 cells
Role of Src family tyrosine kinases in the down-regulation of epidermal growth factor signaling in PC12 cells
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DOI：
10.1111/j.1365-2443.2005.00909.x
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发表时间：
2005-12-01
期刊：
影响因子：
2.1
通讯作者：
Okada, M
中科院分区：
文献类型：
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作者：
Kasai, A;Shima, T;Okada, M
Src家族酪氨酸激酶（SFKs）作为细胞内多种信号转导途径的分子开关，在细胞内发挥着重要的作用。SFKs与表皮生长因子（EGF）信号转导有关，尽管其在该途径中的确切作用机制仍然难以捉摸。为了解决这个问题，我们专注于膜微区，脂筏，SFKs富集。在PC 12细胞中，EGF受体（EGFR）组成性地集中在脂筏中，并且在EGF刺激后发生进一步积累，随后激活SFKs，特别是Src和Yes。抑制SFK或破坏脂筏功能导致EGF诱导的PC 12细胞突起延伸。这些作用伴随着Erk 1/2激活的持续时间延长，并被MEK抑制剂抑制。在Csk（-/-）成纤维细胞中，抑制SFK导致EGF诱导的Erk 1/2活化延长，同时抑制EGFR降解。此外，在PC 12细胞中标记的EGF的行为的分析表明，抑制SFK活性减弱了活化的EGFR在膜上的聚集率。这些结果表明，SFK活性的脂筏是必要的，以促进EGF信号的下调，通过调节聚集在PC 12细胞膜上的活化EGFR。
Src family tyrosine kinases (SFKs) play pivotal roles as molecular switches for various intracellular signaling pathways. SFKs have been implicated in epidermal growth factor (EGF) signaling, although their precise mechanisms of action in this pathway remain elusive. To address this issue, we focused on a membrane microdomain, lipid rafts, where SFKs are enriched. In PC12 cells, the EGF receptor (EGFR) is constitutively concentrated in lipid rafts, and further accumulation takes place upon EGF stimulation, followed by activation of SFKs, especially Src and Yes. Inhibition of SFK or disruption of lipid raft function causes EGF-induced neurite extension of PC12 cells. These effects are accompanied by an extended duration of Erk1/2 activation and are suppressed by a MEK inhibitor. In Csk(-/-) fibroblasts, suppression of SFK results in prolonged EGF-induced activation of Erk1/2, with concomitant suppression of EGFR degradation. Furthermore, analysis of the behavior of labeled EGF in PC12 cells reveals that suppression of SFK activity attenuates the rate of clustering of activated EGFR on the membrane. These results suggest that SFK activity in lipid rafts is required to facilitate the down-regulation of EGF signaling, by regulating the clustering of activated EGFR on the membrane in PC12 cells.