Kinetics of miR-122 Expression in the Liver during Acute HCV Infection

Youkyung Choi,Hans-Peter Dienes,Kris Krawczynski,Birke Bartosch

doi:10.1371/journal.pone.0076501

Youkyung Choi, Hans-Peter Dienes + Show 2 more

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https://doi.org/10.1371/journal.pone.0076501

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Abstract

The relationships among micro RNA-122 (miR-122) expression in the liver, hepatitis C virus (HCV) replication and hepatic damage were analyzed in three chimpanzees observed for 180 days after inoculation with HCV genotype 1a. Levels of miR-122 in the liver and serum were measured by real-time RT PCR in serial liver biopsies and serum samples. Hepatic miR-122 levels were normalized separately for each of three chimpanzees with small RNAs and microRNAs that are endogenous to the liver and are stably expressed. Two- to 4-fold rise in hepatic miR-122 levels was observed at the onset of HCV infection (the first 4 weeks) when HCV titers in the liver and serum increased rapidly in all three chimpanzees in concordance with in vitro data indicating the miR-122 significance for HCV replication. Between 10 to 14 weeks after inoculation, when hepatic and serum HCV RNA titers exceeded 3 logs and alanine aminotransferase (ALT) activity was elevated, hepatic miR-122 levels were in decline. Cumulative data derived from all three chimpanzees from 180 days of observation documented an inverse (negative) correlation between hepatic miR-122 and HCV RNA in the liver and serum and positive correlation between level of serum miR-122 and HCV replication. Subsequent rise of miR-122 level during HCV clearance and ALT normalization suggested a tri-phasic occurrence of the relationship among hepatic miR-122 expression, HCV replication and hepatic destruction, which was the most apparent in one chimpanzee but less evident in two other animals. In vivo kinetics of hepatic and serum miR-122, HCV replication and hepatic destruction reflects complexities of the virus-host interaction during the acute phase of HCV infection.

Highlights

More than 170 million people world-wide are estimated to be chronically infected with hepatitis C virus (HCV), and in the USA, about 25,000 individuals every year are newly infected by HCV
To identify the most stable endogenous RNA as normalizers in hepatic micro RNA-122 (miR-122) expression, twelve small RNAs and miRNAs were selected as candidate endogenous control RNAs
The twelve endogenous control RNAs were expressed in all samples, with cycle threshold (Ct) values ranging from 22.36 to 36.74 in CH256, 18.08 to 44.88 in CH6413, and 22.24 to 35.42 in CH1541. miR-103 was not used for further calculation in CH6413 due to its low expression (Table S1). miR-122 Ct values were observed in range from 20.68 to 29.01 for CH256, 23.74 to 29.03 for CH6413, and 22.79 to 27.78 for CH1541, i.e., in range of Ct values of the endogenous controls

Summary

Introduction

More than 170 million people world-wide are estimated to be chronically infected with HCV, and in the USA, about 25,000 individuals every year are newly infected by HCV. In vitro studies showed high expression of miR-122 in Huh cells hosting HCV replication and documented interaction of miR-122 with the 59-untranslated region (UTR) of the HCV RNA genome [4,11,12]. MiR-122 does not directly stimulate HCV RNA synthesis [14], it facilitates HCV replication by recruiting an RNA-induced silencing complex (RISC) containing Ago (Argonaute-2) protein, mediating the stabilization of HCV, and slowing the 59 decay of the viral genome in infected cells [15,16,17]. It was suggested that miR-122 triggers HCV replication by posttranscriptional repression of heme oxygenase enzyme synthesis [7]

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