Pang Hong-Bo, Braun Gary B, Friman Tomas, Aza-Blanc Pedro, Ruidiaz Manuel E, Sugahara Kazuki N, Teesalu Tambet, Ruoslahti Erkki
Cancer Research Center, Sanford-Burnham Medical Research Institute, La Jolla, California 92037, USA.
1] Cancer Research Center, Sanford-Burnham Medical Research Institute, La Jolla, California 92037, USA [2] Center for Nanomedicine, Department of Cell, Molecular and Developmental Biology, University of California Santa Barbara, Santa Barbara, California 93106-9610, USA.
Nat Commun. 2014 Oct 3;5:4904. doi: 10.1038/ncomms5904.
Neuropilins (NRPs) are trans-membrane receptors involved in axon guidance and vascular development. Many growth factors and other signalling molecules bind to NRPs through a carboxy (C)-terminal, basic sequence motif (C-end Rule or CendR motif). Peptides with this motif (CendR peptides) are taken up into cells by endocytosis. Tumour-homing CendR peptides penetrate through tumour tissue and have shown utility in enhancing drug delivery into tumours. Here we show, using RNAi screening and subsequent validation studies, that NRP1-mediated endocytosis of CendR peptides is distinct from known endocytic pathways. Ultrastructurally, CendR endocytosis resembles macropinocytosis, but is mechanistically different. We also show that nutrient-sensing networks such as mTOR signalling regulate CendR endocytosis and subsequent intercellular transport of CendR cargo, both of which are stimulated by nutrient depletion. As CendR is a bulk transport pathway, our results suggest a role for it in nutrient transport; CendR-enhanced drug delivery then makes use of this natural pathway.
神经纤毛蛋白(NRPs)是参与轴突导向和血管发育的跨膜受体。许多生长因子和其他信号分子通过羧基(C)末端的碱性序列基序(C末端规则或CendR基序)与NRPs结合。具有这种基序的肽(CendR肽)通过内吞作用被细胞摄取。肿瘤归巢CendR肽可穿透肿瘤组织,并已显示出在增强药物向肿瘤内递送方面的效用。在这里,我们通过RNA干扰筛选及后续验证研究表明,CendR肽的NRP1介导的内吞作用不同于已知的内吞途径。在超微结构上,CendR内吞作用类似于巨胞饮作用,但在机制上有所不同。我们还表明,诸如mTOR信号传导等营养感应网络调节CendR内吞作用以及随后CendR货物的细胞间运输,这两者均受营养物质耗竭的刺激。由于CendR是一种批量运输途径,我们的结果表明其在营养物质运输中发挥作用;CendR增强的药物递送则利用了这一自然途径。