title: Apolipoprotein J, a glucose-upregulated molecular chaperone, stabilizes core and NS5A to promote infectious hepatitis C virus virion production.
abstract: OBJECTIVE
  Hepatitis C virus (HCV) infection leads to glucose abnormality. HCV depends on lipid droplets (LDs) and very-low density lipoproteins for assembly/releasing; however, the components and locations for this process remain unidentified. Apolipoprotein J (ApoJ), upregulated by glucose, functions as Golgi chaperone of secreted proteins and resides abundantly in very-low density lipoproteins. This study investigates the interplay between glucose, ApoJ and HCV virion production.
  
  
  METHODS
  The effects of high glucose on ApoJ expression and HCV production were evaluated with cultivated HuH7.5, primary human hepatocytes, and in treatment naive chronic hepatitis C patients. How ApoJ affects HCV lifecycle was assessed using siRNA knockdown strategy in JFH1 infected and subgenomic replicon cells. The interactions and locations of ApoJ with viral and host components were examined by immunoprecipitation, immunofluorescence and subcellular fractionation experiments.
  
  
  RESULTS
  HCV infection increased ApoJ expression, which in parallel with HCV infectivity was additionally elevated with high glucose treatment. Serum ApoJ correlated positively with fasting blood glucose concentration and HCV-RNA titre in patients. ApoJ silencing reduced intracellular and extracellular HCV infectivity and extracellular HCV-RNA, but accumulated intracellular HCV-RNA in HCV-infected cells. ApoJ interacted with HCV core and NS5A and stabilized the dual protein complex. HCV infection dispersed cytoplasmic ApoJ from the compact zones of the Golgi to encircle LDs, where co-localization of the core, NS5A, HCV-RNA, subcellular markers for LDs, endoplasmic reticulum (ER), Golgi, and membrane contact sites occurred.
  
  
  CONCLUSIONS
  ApoJ facilitates infectious HCV particle production via stabilization of core/NS5A, which might surround LDs at the ER-Golgi membrane contact site.
authors.affiliation: Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Chun-Chieh
authors.initials: CC
authors.lastname: Lin
authors.affiliation: Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Peiju
authors.initials: P
authors.lastname: Tsai
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Hung-Yu
authors.initials: HY
authors.lastname: Sun
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Mei-Chi
authors.initials: MC
authors.lastname: Hsu
authors.affiliation: Department of Biotechnology, College of Life Science, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Jin-Ching
authors.initials: JC
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: I-Chin
authors.initials: IC
authors.lastname: Wu
authors.affiliation: Department of Nursing, Chung Hwa University of Medical Technology, Tainan, Taiwan.
authors.forename: Chiung-Wen
authors.initials: CW
authors.lastname: Tsao
authors.affiliation: Department of Internal Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Center of Infectious Disease and Signaling Research, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Ting-Tsung
authors.initials: TT
authors.lastname: Chang
authors.affiliation: Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Center of Infectious Disease and Signaling Research, College of Medicine, National Cheng Kung University, Tainan, Taiwan. Electronic address: t7908077@mail.ncku.edu.tw.
authors.forename: Kung-Chia
authors.initials: KC
authors.lastname: Young
mesh_terms: D000328:Adult; D000368:Aged; D002460:Cell Line; D051152:Clusterin / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications; D005260:Female; D005947:Glucose / Q000378:metabolism; D016174:Hepacivirus / Q000472:pathogenicity / Q000502:physiology*; D019698:Hepatitis C, Chronic / Q000150:complications / Q000378:metabolism* / Q000821:virology*; D022781:Hepatocytes / Q000378:metabolism / Q000821:virology; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D055550:Protein Stability; D015854:Up-Regulation; D014758:Viral Core Proteins / Q000378:metabolism*; D017361:Viral Nonstructural Proteins / Q000378:metabolism*; D014771:Virion / Q000472:pathogenicity / Q000502:physiology; D014779:Virus Replication; D012324:RNA-Dependent RNA Polymerase
chemical_list: D051152:Clusterin; D005947:Glucose; D014758:Viral Core Proteins; D017361:Viral Nonstructural Proteins; C495242:CLU protein, human; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase
keywords: Endoplasmic reticulum; Golgi; Lipid droplet; Membrane contact site; Small heat shock protein