RT Journal Article
SR Electronic
T1 On the shuttling across the blood-brain barrier via tubules formation: mechanism and cargo avidity bias
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.04.04.025866
DO 10.1101/2020.04.04.025866
A1 Xiaohe Tian
A1 Diana Moreira Leite
A1 Edoardo Scarpa
A1 Sophie Nyberg
A1 Gavin Fullstone
A1 Joe Forth
A1 Diana Lourenço Matias
A1 Azzurra Apriceno
A1 Alessandro Poma
A1 Aroa Duro-Castano
A1 Manish Vuyyuru
A1 Lena Harker-Kirschneck
A1 Anđela Šarić
A1 Zhongping Zhang
A1 Pan Xiang
A1 Bin Fang
A1 Yupeng Tian
A1 Lei Luo
A1 Loris Rizzello
A1 Giuseppe Battaglia
YR 2020
UL http://biorxiv.org/content/early/2020/04/05/2020.04.04.025866.abstract
AB The blood-brain barrier is made of polarised brain endothelial cells (BECs) phenotypically conditioned by the central nervous system (CNS). Transport across BECs is of paramount importance for nutrient uptake as well as to rid the brain of waste products. Nevertheless, currently we do not understand how large macromolecular cargo shuttles across and how BECs discriminate between the brain-bound and own nutrients. Here, we study the low-density lipoprotein receptor-related protein 1 (LRP1) an essential regulator of BEC transport, and show that it is associated with endocytic effectors, endo-lysosomal compartments as well as syndapin-2, a member of the Bin/Amphiphysin/Rvs (BAR) domain superfamily known to stabilise tubular carriers. We employed synthetic self-assembled vesicles, polymersomes, as a multivalent system with tunable avidity as a tool to investigate the mechanism of transport across BECs. We used a combination of conventional and super-resolution microscopy, both in vivo and in vitro, accompanied with biophysical modelling of transport kinetics and membrane-bound interactions. Our results demonstrate that the avidity of the ligand-receptor interaction (the overall cargo binding energy) determines the mechanism of sorting during the early stages of endocytosis and consequent trafficking. We show that high avidity cargo biases the LRP1 towards internalisation and fast degradation in BECs, while mid avidity augments the formation of syndapin-2 stabilised tubular carriers and promotes fast shuttling across BECs. Thus, we map out a very detailed mechanism where clathrin, actin, syndapin-2, dynamin and SNARE act synergistically to enable fast shuttling across BECs.