A clathrin-dependent pathway leads to KRas signaling on late endosomes en route to lysosomes
A clathrin-dependent pathway leads to KRas signaling on late endosomes en route to lysosomes
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DOI：
10.1083/jcb.200807186
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发表时间：
2009-03-23
影响因子：
7.8
通讯作者：
Bachs, Oriol
中科院分区：
文献类型：
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作者：
Lu, Albert;Tebar, Francesc;Bachs, Oriol
RAS蛋白是一种小的鸟苷三磷酸酶，参与调节重要的细胞功能，如增殖、分化和凋亡。了解RAS蛋白在细胞内的运输对于识别新的RAS信号平台至关重要。在这项研究中，我们报道了表皮生长因子通过依赖于笼蛋白的途径触发Kirsten Ras(KRAS)转位到内膜上(不依赖于钙调蛋白和蛋白激酶C的磷酸化)。从早期内小体中，KRAS而不是Harvey RAS或神经母细胞瘤RAS被分选并运输到晚期内小体(LES)和溶酶体。利用黄色荧光蛋白-Raf1和Raichu-KRAS探针，我们首次在活体内鉴定了Rab7 LES上的活性KRAS，引发了通过Raf1的信号输出。在这些LE上，我们还鉴定了p14-MP1支架复合体和激活的细胞外信号调节激酶1/2。溶酶体功能的丧失导致持续的晚期内体有丝分裂原激活的蛋白激酶信号输出。总之，这项研究揭示了KRAS在细胞内运输和信号传递的新方面，为控制细胞内RAS调控的机制提供了新的线索。
Ras proteins are small guanosine triphosphatases involved in the regulation of important cellular functions such as proliferation, differentiation, and apoptosis. Understanding the intracellular trafficking of Ras proteins is crucial to identify novel Ras signaling platforms. In this study, we report that epidermal growth factor triggers Kirsten Ras (KRas) translocation onto endosomal membranes (independently of calmodulin and protein kinase C phosphorylation) through a clathrin-dependent pathway. From early endosomes, KRas but not Harvey Ras or neuroblastoma Ras is sorted and transported to late endosomes (LEs) and lysosomes. Using yellow fluorescent protein-Raf1 and the Raichu-KRas probe, we identified for the first time in vivo active KRas on Rab7 LEs, eliciting a signal output through Raf1. On these LEs, we also identified the p14-MP1 scaffolding complex and activated extracellular signal-regulated kinase 1/2. Abrogation of lysosomal function leads to a sustained late endosomal mitogen-activated protein kinase signal output. Altogether, this study reveals novel aspects about KRas intracellular trafficking and signaling, shedding new light on the mechanisms controlling Ras regulation in the cell.