title: Ubiquitin-coated nanodiamonds bind to autophagy receptors for entry into the selective autophagy pathway.
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.
authors.affiliation: a Department and Institute of Biological Science and Technology , National Chiao Tung University , Hsinchu , Taiwan.
authors.forename: Kuang-Kai
authors.initials: KK
authors.lastname: Liu
authors.affiliation: b Institute of Molecular Medicine and Bioengineering, National Chiao Tung University , Hsinchu , Taiwan.
authors.forename: Wei-Ru
authors.initials: WR
authors.lastname: Qiu
authors.affiliation: b Institute of Molecular Medicine and Bioengineering, National Chiao Tung University , Hsinchu , Taiwan.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Naveen Raj
authors.affiliation: a Department and Institute of Biological Science and Technology , National Chiao Tung University , Hsinchu , Taiwan.
authors.forename: Huei-Fang
authors.initials: HF
authors.lastname: Liu
authors.affiliation: a Department and Institute of Biological Science and Technology , National Chiao Tung University , Hsinchu , Taiwan.
authors.forename: Hou-Syun
authors.initials: HS
authors.lastname: Huang
authors.affiliation: b Institute of Molecular Medicine and Bioengineering, National Chiao Tung University , Hsinchu , Taiwan.
authors.forename: Yu-Wei
authors.initials: YW
authors.lastname: Lin
authors.affiliation: a Department and Institute of Biological Science and Technology , National Chiao Tung University , Hsinchu , Taiwan.
authors.forename: Chien-Jen
authors.initials: CJ
authors.lastname: Chang
authors.affiliation: a Department and Institute of Biological Science and Technology , National Chiao Tung University , Hsinchu , Taiwan.
authors.forename: Ting-Hua
authors.initials: TH
authors.lastname: Chen
authors.affiliation: c Department of Chemistry , National Dong Hwa University , Hualien , Taiwan.
authors.forename: Chinpiao
authors.initials: C
authors.lastname: Chen
authors.affiliation: d Institute of Atomic and Molecular Sciences, Academia Sinica , Taipei , Taiwan.
authors.forename: Huan-Cheng
authors.initials: HC
authors.lastname: Chang
authors.affiliation: e Institute of Bioinformatics and Systems Biology, National Chiao Tung University , Hsinchu , Taiwan.
authors.forename: Jenn-Kang
authors.initials: JK
authors.lastname: Hwang
authors.affiliation: a Department and Institute of Biological Science and Technology , National Chiao Tung University , Hsinchu , Taiwan.|b Institute of Molecular Medicine and Bioengineering, National Chiao Tung University , Hsinchu , Taiwan.
authors.forename: Jui-I
authors.initials: JI
authors.lastname: Chao
mesh_terms: D000072283:A549 Cells; D000818:Animals; D001343:Autophagy; D016923:Cell Death; D045744:Cell Line, Tumor; D016922:Cellular Senescence; D049452:Green Fluorescent Proteins / Q000737:chemistry; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D018613:Microscopy, Confocal; D008869:Microtubule-Associated Proteins / Q000737:chemistry; D058612:Nanodiamonds / Q000737:chemistry*; D009368:Neoplasm Transplantation; D009419:Nerve Tissue Proteins / Q000737:chemistry; D009687:Nuclear Proteins / Q000737:chemistry; D011485:Protein Binding; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry; D011994:Recombinant Proteins / Q000737:chemistry; D000071456:Sequestosome-1 Protein / Q000737:chemistry; D025801:Ubiquitin / Q000737:chemistry*
chemical_list: C094297:CALCOCO2 protein, human; C477012:MAP1LC3A protein, human; C480860:Map1lc3b protein, mouse; D008869:Microtubule-Associated Proteins; C000597434:NDP52 protein, mouse; D058612:Nanodiamonds; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D011994:Recombinant Proteins; C099718:SQSTM1 protein, human; D000071456:Sequestosome-1 Protein; C101343:Sqstm1 protein, mouse; D025801:Ubiquitin; D049452:Green Fluorescent Proteins
keywords: autophagy receptors; lysosome; nanodiamonds; selective autophagy; ubiquitin