Transcriptomics

Dataset Information

24

Increased hemoglobin expression in NASH livers


ABSTRACT: BACKGROUND & AIMS: Recent studies revealed that hemoglobin is expressed in some non-erythrocytes and it suppresses oxidative stress when overexpressed. Oxidative stress plays a critical role in the pathogenesis of non-alcoholic steatohepatitis (NASH). This study was to investigate whether hemoglobin is expressed in hepatocytes and how it is related to oxidative stress in NASH patients. METHODS: Microarray was performed to identify differentially expressed genes in NASH. Quantitative real time PCR (qRT-PCR) was used to examine gene expression levels. Western blotting and immunofluorescence staining were employed to examine hemoglobin proteins. Flow cytometry was used to measure intracellular oxidative stress. RESULTS: Analysis of microarray gene expression data has revealed a significant increase in the expression of hemoglobin alpha (HBA1) and beta (HBB) in liver biopspies from NASH patients. Increased hemoglobin expression in NASH was validated by qRT-PCR. However, the expression of erythrocyte specific marker genes such as SPTA, SPTB, GYPA, GATA1, and ALAS2 did not change, indicating that increased hemoglobin expression in NASH was not from erythropoiesis, but could result from increased expression in hepatocytes. Immunofluorescence staining demonstrated positive HBA1 and HBB expression in the hepatocytes of NASH livers. Hemoglobin expression was also observed in human hepatocellular carcinoma HepG2 cell line. Furthermore, treatment with hydrogen peroxide, a known oxidative stress inducer, induced a dose dependent increase in HBA1 expression in HepG2 cells. Intriguingly, forced hemoglobin expression suppressed oxidative stress. CONCLUSIONS: Oxidative stress upregulates hemoglobin expression in hepatocytes. Suppression of oxidative stress by hemoglobin could be a mechanism to protect hepatocytes from oxidative damage. These findings suggest that hemoglobin is an inducible antioxidant in hepatocytes in response to increased oxidative stress as found in NASH livers. Twelve biopsy diagnosed NASH patients were included in this study. For control groups, total RNA from 5 different subjects were purchased from ADMET. These subjects are free from liver disease.

ORGANISM(S): Homo sapiens  

SUBMITTER: Susan S Baker   Lixin Zhu  Norma J Nowak  Wensheng Liu  Susan Baker  Robert D Baker 

PROVIDER: E-GEOD-24807 | ArrayExpress | 2010-10-20

SECONDARY ACCESSION(S): GSE24807PRJNA132303

REPOSITORIES: GEO, ArrayExpress

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Publications

Upregulation of hemoglobin expression by oxidative stress in hepatocytes and its implication in nonalcoholic steatohepatitis.

Liu Wensheng W   Baker Susan S SS   Baker Robert D RD   Nowak Norma J NJ   Zhu Lixin L  

PloS one 20110912 9


Recent studies revealed that hemoglobin is expressed in some non-erythrocytes and it suppresses oxidative stress when overexpressed. Oxidative stress plays a critical role in the pathogenesis of non-alcoholic steatohepatitis (NASH). This study was designed to investigate whether hemoglobin is expressed in hepatocytes and how it is related to oxidative stress in NASH patients. Analysis of microarray gene expression data revealed a significant increase in the expression of hemoglobin alpha (HBA1)  ...[more]

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