title: Mitochondrial Lon regulates apoptosis through the association with Hsp60-mtHsp70 complex.
abstract: Human Lon protease is a mitochondrial matrix protein with several functions, including protein degradation, mitochondrial DNA (mtDNA) binding, and chaperone activity. Lon is currently emerging as an important regulator of mitochondria-contributed tumorigenesis due to its overexpression in cancer cells. To understand the mechanism of increased Lon in tumor cells, we studied the interactome to identify the chaperone Lon-associated proteins by proteomics approaches using the cells overexpressing Lon. In the present study, we designed a method connecting co-immunoprecipitation (Co-IP) to in-solution digestion for the shotgun mass spectrometry. We identified 76 proteins that were putative Lon-associated proteins that participated in mitochondrial chaperone system, cellular metabolism and energy, cell death and survival, and mtDNA stability. The association between Lon and NDUFS8 or Hsp60-mtHsp70 complex was confirmed by Co-IP and immunofluorescence co-localization assay. We then found that the protein stability/level of Hsp60-mtHsp70 complex depends on the level of Lon under oxidative stress. Most importantly, the ability of increased Lon-inhibited apoptosis is dependent on Hsp60 that binds p53 to inhibit apoptosis. These results suggest that the mechanism underlying cell survival regulated by Lon is mediated by the maintenance of the protein stability of Hsp60-mtHsp70 complex. This new knowledge of chaperone Lon interactome will allow us to better understand the cellular mechanism of Lon in mitochondrial function and of its overexpression in enhancing cell survival and tumorigenesis.
authors: Department of Medical Laboratory Science and Biotechnology, Yuanpei University, Hsinchu 300, Taiwan.
authors: T-Y
authors: TY
authors: Kao
authors: 1] Department of Medical Laboratory Science and Biotechnology, Yuanpei University, Hsinchu 300, Taiwan [2] National Institute of Cancer Research, National Health Research Institutes, Zhunan, Miaoli 35053, Taiwan.
authors: Y-C
authors: YC
authors: Chiu
authors: 1] National Institute of Cancer Research, National Health Research Institutes, Zhunan, Miaoli 35053, Taiwan [2] Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan [3] Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan.
authors: W-C
authors: WC
authors: Fang
authors: National Institute of Cancer Research, National Health Research Institutes, Zhunan, Miaoli 35053, Taiwan.
authors: C-W
authors: CW
authors: Cheng
authors: National Institute of Cancer Research, National Health Research Institutes, Zhunan, Miaoli 35053, Taiwan.
authors: C-Y
authors: CY
authors: Kuo
authors: 1] Institute of Molecular and Cellular Biology, National Taiwan University, Taipei 106, Taiwan [2] Department of Life Science, National Taiwan University, Taipei 106, Taiwan.
authors: H-F
authors: HF
authors: Juan
authors: 1] Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan [2] Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan [3] Department of Chemistry, National Taiwan University, Taipei 106, Taiwan.
authors: S-H
authors: SH
authors: Wu
authors: 1] National Institute of Cancer Research, National Health Research Institutes, Zhunan, Miaoli 35053, Taiwan [2] Graduate Institute of Basic Medical Science, China Medical University, Taichung 404, Taiwan.
authors: A Y-L
authors: AY
authors: Lee
mesh_terms: D017209:Apoptosis; D015153:Blotting, Western; D002460:Cell Line; D002470:Cell Survival / Q000235:genetics / Q000502:physiology; D018834:Chaperonin 60 / Q000378:metabolism*; D019295:Computational Biology; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation; D008928:Mitochondria / Q000201:enzymology*; D049070:Protease La / Q000378:metabolism*; D011485:Protein Binding; D053719:Tandem Mass Spectrometry
chemical_list: D018834:Chaperonin 60; D018840:HSP70 Heat-Shock Proteins; D049070:Protease La