1. Academic Validation
  2. Cell surface nucleolin is a novel ADAMTS5 receptor mediating endothelial cell apoptosis

Cell surface nucleolin is a novel ADAMTS5 receptor mediating endothelial cell apoptosis

  • Cell Death Dis. 2022 Feb 23;13(2):172. doi: 10.1038/s41419-022-04618-x.
Dogan Can Kirman 1 Bhuvanasundar Renganathan 1 Wai Kit Chui 1 Ming Wei Chen 2 Neslihan Arife Kaya 2 3 Ruowen Ge 4
Affiliations

Affiliations

  • 1 Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 117543, Singapore.
  • 2 School of Biological Sciences, Nanyang Technological University, Singapore, 637551, Singapore.
  • 3 Genome Institute of Singapore, Agency for Science, Technology and Research, Singapore, 138672, Singapore.
  • 4 Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 117543, Singapore. dbsgerw@nus.edu.sg.
Abstract

A Disintegrin and Metalloproteinase with ThromboSpondin motif (ADAMTS) 5 functions as an anti-angiogenic and anti-cancer protein independent of its metalloproteinase activity. Both full-length ADAMTS5 and TS5-p45, the autocatalytically cleaved C-terminal 45 kDa truncate of ADAMTS5, inhibits angiogenesis, and induces endothelial cell (EC) Apoptosis. However, how ADAMTS5 triggers EC Apoptosis remains unclear. This work shows that Caspase-8 (Cas-8) and caspase-9 (Cas-9) are involved in TS5-p45-induced EC Apoptosis. We identify cell surface nucleolin (NCL) as a novel high-affinity receptor for TS5-p45 in ECs, mediating TS5-p45's cell surface binding and pro-apoptotic function. We show that the central RNA-binding domain (RBD) of NCL is essential and sufficient for its binding to TS5-p45. Upon interacting with EC surface NCL, TS5-p45 is internalized through clathrin- and caveolin-dependent endocytosis and trafficked to the nucleus via late endosomes (LEs). We demonstrate that the nuclear trafficking of TS5-p45 is important for its pro-apoptotic activity as disruption of LE membrane integrity with an endosomolytic peptide suppressed both nuclear trafficking and pro-apoptotic activity of TS5-p45. Through cell surface biotinylation, we revealed that cell surface NCL shuttles extracellular TS5-p45 to the nucleus to mediate Apoptosis. Furthermore, blocking the importin α1/ß1 receptor hindered the nuclear trafficking of TS5-p45, suggesting the involvement of the nuclear importing machinery for this nuclear translocation. RNA-seq identified many apoptosis-related genes that are differentially expressed at least two-fold in TS5-p45-treated ECs, with 10 of them qRT-PCR-validated and at least 5 of these genes potentially contributing to TS5-p45-NCL-induced Apoptosis. Altogether, our work identifies NCL as a novel cell surface receptor for ADAMTS5 and demonstrates the critical role of NCL-mediated internalization and nuclear trafficking for ADAMTS5-induced EC Apoptosis. These findings reveal novel mechanistic insights of the secreted metalloproteinase ADAMTS5 in angiogenesis inhibition.

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