| Περίληψη: | Clinical studies have suggested that some hepatitis c virus (hcv) genotypes or
isolates are associated with disease progression and hepatocellular carcinoma
development (hcc). In addition to its known role in viral particle, hcv core protein
may be directly involved in these pathogenic features affecting host’s signaling
pathways. Hcv core protein was shown to interfere with host wnt/ β-cateninpathway.
This work aims at investigating the role of hcv core genetic variability in the
regulation of the wnt/ β-cateninpathway during hcv infection. Tcf element
transactivational activity was assessed in transiently transfected cell lines expressing
hcv core protein variants derived from clinical isolates of subtypes 1a, 4aR and 4fC.
We demonstrated that HCV core protein up-regulates TCF element transactivation in a
strain-specific manner, in transiently transfected cells, through a mechanism involving
PI3K activation. Site-directed mutagenesis confirmed the role of amino acid Thr71 and
Ser64 on tcf element transactivation. Genome-length recombinant chimeras were
generated by exchanging the core-coding region of cell-culture adapted jfh1-derived
strain with equivalent sequences from clinical isolates. After characterization of the new
intergenotypic chimeric viruses high titer stocks were produced. qpcr, confocal
microscopy and image analysis was performed to monitor the activation status of Wnt/
β-cateninpathway determinants during infection. In agreement, infection of hepatic cells
with core-intergenotypic recombinant viruses resulted in strain-specific transcriptional
up-regulation of tbx3, c-myc, axin2, fibronectin, fasn and cyclin d1 genes and
nuclear translocation of β-catenin. Intergenotypic core recombinant viruses revealed a
putative functional domain within region 64-71 aa of core that may interact with
cellular proteins which leads to wnt/ β-cateninpathway activation. Further studies are
conducted to identify this cellular target and define the molecular mechanism of core
action. HCV core intergenotypic recombinants developed provide a model system to
study the role of Hcv core natural mutations in the dysregulation of host pathways
associated with liver disease in a relevant infection system, like primary cell lines and
animal model systems. This study is expected to shed light on the molecular
mechanisms underlying the association between hepatitis C virus genomic variability
and hepatocellular carcinoma development.
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