Case Control Study
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World J Gastroenterol. Apr 28, 2014; 20(16): 4778-4786
Published online Apr 28, 2014. doi: 10.3748/wjg.v20.i16.4778
Proteomic analysis of liver mitochondria from rats with nonalcoholic steatohepatitis
Lin Li, De-Zhao Lu, You-Ming Li, Xue-Qun Zhang, Xin-Xin Zhou, Xi Jin
Lin Li, You-Ming Li, Xue-Qun Zhang, Xin-Xin Zhou, Xi Jin, Department of Gastroenterology, the First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310003, Zhejiang Province, China
De-Zhao Lu, College of Life Sciences, Zhejiang Chinese Medical University, Hangzhou 310003, Zhejiang Province, China
Author contributions: Li L and Lu DZ performed the majority of experiments; Li YM, Zhang XQ and Zhou XX provided vital regents and analytical tools and were also involved in editing the manuscript; Jin X designed the study and wrote the manuscript.
Supported by National Natural Science Foundation of China No. 81000169, No. 81100277, No. 81370008, and No. 81200284; the Excellent Young Investigator Foundation of the Health Bureau of Zhejiang Province No. 2010QNA011; the Excellent Young Investigator Natural Science Foundation of Zhejiang Province No. R2110159; the Project of Zhejiang Traditional Chinese Medicine Administration Bureau No. 2010ZA065; and the Fundamental Research Funds for the Central Universities No. 2013QNA702
Correspondence to: Dr. Xi Jin, the First Affiliated Hospital, College of Medicine, Zhejiang University, No. 79 Qingchun Road, Hangzhou 310003, Zhejiang Province, China. jxfl007@hotmail.com
Telephone: +86-571-87236603 Fax: +86-571-87236611
Received: January 3, 2014
Revised: February 7, 2014
Accepted: March 5, 2014
Published online: April 28, 2014
Abstract

AIM: To explore mitochondrial dysfunction in nonalcoholic steatohepatitis (NASH) by analyzing the proteome of liver mitochondria from a NASH model.

METHODS: The NASH rat model was established by feeding rats a fat-rich diet for 24 wk and was confirmed using hematoxylin and eosin staining of liver tissue and by changes in the levels of serum alanine transaminase, aspartate aminotransferase, triglyceride, total cholesterol and other markers. Liver mitochondria from each group were isolated using differential centrifugation. The mitochondrial samples were lyzed, purified and further analyzed using two-dimensional electrophoresis combined with matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry. Bioinformatic analyses of assigned gene ontology and biological pathway was used to study functional enrichments in the abundant proteomic data.

RESULTS: Eight up-regulated and sixteen down-regulated proteins were identified that showed greater than 1.5-fold differences between the controls and the NASH group. These dysregulated proteins were predicted to be involved in different metabolic processes including fatty acid β-oxidation processes, lipid metabolic processes, cell-cycle arrest, cell polarity maintenance, and adenosine triphosphate/sex hormone metabolic processes. Novel proteins that may be involved in NASH pathogenesis including the trifunctional enzyme Hadha, thyroxine, prohibitin, aldehyde dehydrogenase ALDH1L2, UDP-glucuronosyltransferase 2B31, and carbamoyl-phosphate synthase were identified using bioinformatics tools. The decreased expression of Hadha in NASH liver was verified by Western blotting, which was used as a complementary technique to confirm the proteomic results.

CONCLUSION: This novel report on the liver mitochondrial proteome of a NASH model may provide a reservoir of information on the pathogenesis and treatment of NASH.

Keywords: Nonalcoholic steatohepatitis, Hadha, Proteomics, Rat model

Core tip: Nonalcoholic fatty liver disease (NAFLD) is a major worldwide cause of chronic liver diseases, and nonalcoholic steatohepatitis (NASH) plays a critical role as a “turning point” in the development of NAFLD. Nevertheless, the pathogenesis of NASH remains unclear, and mitochondrial dysfunction is known to be actively involved. To date, no study has reported on specific protein expression patterns in NASH mitochondria. We have, for the first time, performed a proteomic analysis of mitochondria from NASH rats, aiming to provide a protein reservoir for in-depth analyses of NASH mechanisms and for the exploration of potential therapeutics.