title: Lipid disorder and intrahepatic renin-angiotensin system activation synergistically contribute to non-alcoholic fatty liver disease.
abstract: This study aimed to investigate the possible synergistic effects of lipid disorder with renin-angiotensin system (RAS) activation in non-alcoholic fatty liver disease (NAFLD).
  
  
  
  Apolipoprotein E gene-knockout mice, angiotensin II (Ang II) type 1 receptor (AT1) gene-knockout mice and human hepatoblastoma cell line (HepG2) were used for experiments. Lipid accumulation was examined by Filipin staining and intracellular cholesterol quantitative assay. The gene and protein expression of molecules involved in RAS and low-density lipoprotein receptor (LDLr) pathway was examined by real-time PCR, immunofluorescent staining and Western blot.
  
  
  
  There was significantly increased expression of RAS components and extracellular matrix (ECM) in livers of high-fat-diet-fed apolipoprotein E gene-knockout mice compared with controls. Upregulation of RAS components was positively associated with increased plasma levels of lipid profile. The in vitro study further confirmed that cholesterol loading increased supernatant renin activity and Ang II level of HepG2 cells, accompanied by increased ECM production that was positively associated with increased expression of intracellular RAS components. Interestingly, Ang II treatment increased lipid accumulation in livers of C57BL/6 mice and HepG2 cells. Furthermore, Ang II treatment increased gene and protein expression of sterol regulatory element-binding protein (SREBP) cleavage activating protein (SCAP), SREBP-2 and LDLr, which were mediated by enhanced SCAP/SREBP-2 complex translocation from endoplasmic reticulum to Golgi. However, LDLr pathway was accordingly downregulated in livers of AT1 gene-knockout C57BL/6 mice or in HepG2 cells treated by telmisartan.
  
  
  
  These findings demonstrate that lipid disorder and intrahepatic RAS activation synergistically accelerate NAFLD progression.
authors.affiliation: Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing City, Jiangsu Province, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing City, Jiangsu Province, China. klma05@163.com.
authors.forename: Kun L
authors.initials: KL
authors.lastname: Ma
authors.affiliation: Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing City, Jiangsu Province, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing City, Jiangsu Province, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wen
authors.affiliation: Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing City, Jiangsu Province, China.
authors.forename: Gui H
authors.initials: GH
authors.lastname: Wang
authors.affiliation: Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing City, Jiangsu Province, China.
authors.forename: Ze B
authors.initials: ZB
authors.lastname: Hu
authors.affiliation: Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing City, Jiangsu Province, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Liu
authors.affiliation: Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing City, Jiangsu Province, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Lu
authors.affiliation: Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing City, Jiangsu Province, China.
authors.forename: Pei P
authors.initials: PP
authors.lastname: Chen
authors.affiliation: Centre for Nephrology, University College London (UCL) Medical School, Royal Free Campus, London, UK.
authors.forename: Xiong Z
authors.initials: XZ
authors.lastname: Ruan
authors.affiliation: Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing City, Jiangsu Province, China.
authors.forename: Bi C
authors.initials: BC
authors.lastname: Liu
mesh_terms: D000804:Angiotensin II / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001562:Benzimidazoles / Q000494:pharmacology; D001565:Benzoates / Q000494:pharmacology; D002784:Cholesterol / Q000378:metabolism; D059305:Diet, High-Fat; D050171:Dyslipidemias / Q000503:physiopathology*; D005109:Extracellular Matrix / Q000378:metabolism*; D056945:Hep G2 Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D050356:Lipid Metabolism / Q000187:drug effects; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D065626:Non-alcoholic Fatty Liver Disease / Q000503:physiopathology*; D044140:Receptor, Angiotensin, Type 1 / Q000235:genetics; D011973:Receptors, LDL / Q000378:metabolism*; D012084:Renin-Angiotensin System; D015398:Signal Transduction; D051782:Sterol Regulatory Element Binding Protein 2 / Q000235:genetics / Q000378:metabolism; D000077333:Telmisartan
chemical_list: D001562:Benzimidazoles; D001565:Benzoates; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D044140:Receptor, Angiotensin, Type 1; D011973:Receptors, LDL; C102196:SREBP cleavage-activating protein; C497391:Srebf2 protein, mouse; D051782:Sterol Regulatory Element Binding Protein 2; D000804:Angiotensin II; D002784:Cholesterol; D000077333:Telmisartan
keywords: LDLr pathway; extracellular matrix; lipid disorder; non-alcoholic fatty liver disease; renin-angiotensin system