Ubiquitin-coated nanodiamonds bind to autophagy receptors for entry into the selective autophagy pathway

Kuang Kai Liu, Wei Ru Qiu, Emmanuel Naveen Raj, Huei Fang Liu, Hou Syun Huang, Yu Wei Lin, Chien Jen Chang, Ting Hua Chen, Chinpiao Chen, Huan Cheng Chang, Jenn Kang Hwang, Jui-I Chao*

*Corresponding author for this work

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

Selective macroautophagy/autophagy plays a pivotal role in the processing of foreign pathogens and cellular components to maintain homeostasis in human cells. To date, numerous studies have demonstrated the uptake of nanoparticles by cells, but their intracellular processing through selective autophagy remains unclear. Here we show that carbon-based nanodiamonds (NDs) coated with ubiquitin (Ub) bind to autophagy receptors (SQSTM1 [sequestosome 1], OPTN [optineurin], and CALCOCO2/NDP52 [calcium binding and coiled-coil domain 2]) and are then linked to MAP1LC3/LC3 (microtubule-associated protein 1 light chain 3) for entry into the selective autophagy pathway. NDs are ultimately delivered to lysosomes. Ectopically expressed SQSTM1-green fluorescence protein (GFP) could bind to the Ub-coated NDs. By contrast, the Ub-associated domain mutant of SQSTM1 (ΔUBA)-GFP did not bind to the Ub-coated NDs. Chloroquine, an autophagy inhibitor, prevented the ND-containing autophagosomes from fusing with lysosomes. Furthermore, autophagy receptors OPTN and CALCOCO2/NDP52, involved in the processing of bacteria, were found to be involved in the selective autophagy of NDs. However, ND particles located in the lysosomes of cells did not induce mitotic blockage, senescence, or cell death. Single ND clusters in the lysosomes of cells were observed in the xenografted human lung tumors of nude mice. This study demonstrated for the first time that Ub-coated nanoparticles bind to autophagy receptors for entry into the selective autophagy pathway, facilitating their delivery to lysosomes.

Original languageEnglish
Pages (from-to)187-200
Number of pages14
JournalAutophagy
Volume13
Issue number1
DOIs
StatePublished - 2 Jan 2017

Keywords

  • autophagy receptors
  • lysosome
  • nanodiamonds
  • selective autophagy
  • ubiquitin

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    Liu, K. K., Qiu, W. R., Naveen Raj, E., Liu, H. F., Huang, H. S., Lin, Y. W., Chang, C. J., Chen, T. H., Chen, C., Chang, H. C., Hwang, J. K., & Chao, J-I. (2017). Ubiquitin-coated nanodiamonds bind to autophagy receptors for entry into the selective autophagy pathway. Autophagy, 13(1), 187-200. https://doi.org/10.1080/15548627.2016.1254864