The endocytosis of oxidized LDL via the activation of the angiotensin II type 1 receptor

Toshimasa Takahashi,Futoshi Nakagami,Hikari Takeshita,Akemi Kakino,Ken Sugimoto,Hiromi Rakugi,Kazuhiro Hongyo,Masao Takeda,Taku Fujimoto,Yasushi Takeya,Motonori Nagasawa,Tatsuo Kawai,Yibin Huang,Yoichi Nozato,Fei Kang,Serina Yokoyama,Herbert Y Gaisano,Yuki Imaizumi,Tatsuya Sawamura,Yoichi Takami,Hiroshi Akasaka,Satoko Nozato,Go Hamano,Kōichi Yamamoto

doi:10.1016/j.isci.2021.102076

Toshimasa Takahashi, Futoshi Nakagami + Show 22 more

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https://doi.org/10.1016/j.isci.2021.102076

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Abstract

SummaryArrestin-dependent activation of a G-protein-coupled receptor (GPCR) triggers endocytotic internalization of the receptor complex. We analyzed the interaction between the pattern recognition receptor (PRR) lectin-like oxidized low-density lipoprotein (oxLDL) receptor (LOX-1) and the GPCR angiotensin II type 1 receptor (AT1) to report a hitherto unidentified mechanism whereby internalization of the GPCR mediates cellular endocytosis of the PRR ligand. Using genetically modified Chinese hamster ovary cells, we found that oxLDL activates Gαi but not the Gαq pathway of AT1 in the presence of LOX-1. Endocytosis of the oxLDL-LOX-1 complex through the AT1-β-arrestin pathway was demonstrated by real-time imaging of the membrane dynamics of LOX-1 and visualization of endocytosis of oxLDL. Finally, this endocytotic pathway involving GPCR kinases (GRKs), β-arrestin, and clathrin is relevant in accumulating oxLDL in human vascular endothelial cells. Together, our findings indicate that oxLDL activates selective G proteins and β-arrestin-dependent internalization of AT1, whereby the oxLDL-LOX-1 complex undergoes endocytosis.

Highlights

Seven-transmembrane G-protein-coupled receptors (GPCRs) have long been attractive targets for drug discovery and development, as evidenced by the fact that about one-third of all drug targets are GPCRs (Santos et al, 2017)
We recently reported that the angiotensin II type 1 receptor (AT1), a member of the class A GPCR family, forms a complex with the single transmembrane lectin-like oxidized low-density lipoprotein receptor lipoprotein receptor-1 (LOX-1) on the cellular membrane and thereby mediates oxLDL-induced AT1 activation, leading to vascular endothelial dysfunction in mice (Yamamoto et al, 2015)
We previously found that the proximity between LOX-1 and AT1 on the cellular membrane was absent between LOX-1 and the angiotensin II (Ang II) type receptor (AT2), which is the isoform of AT1, in an in situ proximity ligation assay (PLA), indicating that LOX-1 binds to AT1 (Yamamoto et al, 2015)

Summary

Introduction

Seven-transmembrane G-protein-coupled receptors (GPCRs) have long been attractive targets for drug discovery and development, as evidenced by the fact that about one-third of all drug targets are GPCRs (Santos et al, 2017). In addition to canonical activation by binding of the cognate ligand, recent understanding of the allosteric activation pathways of GPCRs has revealed the diversity in the physiological and pathological roles of this receptor family (Gentry et al, 2015; Khoury et al, 2014; Wootten et al, 2013). The allosteric ligands of GPCRs trigger a cellular response distinct from that elicited by orthosteric ligands by differentially regulating activation of G proteins and arrestins, the latter primarily mediating cellular trafficking of receptor complexes (Jean-Charles et al, 2017; Ranjan et al, 2017; Smith and Rajagopal, 2016). The precise molecular pathways that are activated upon stimulation remain largely undetermined in this case

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