Stability of CXCL-8 and related AU-rich mRNAs in the context of hepatitis C virus replication in vitro.
BACKGROUND
Previous studies have shown that levels of CXCL-8 are elevated in patients with chronic hepatitis C virus (HCV) infection and are highest in nonresponders to interferon (IFN) therapy and that CXCL-8 inhibits IFN antiviral action. CXCL-8 expression involves AU-rich elements (AREs) in 3' untranslated regions that regulate mRNA stability. CXCL-8 mRNA stability was, therefore, investigated in the context of HCV replication in 4 replicon cell lines, Huh7 and Huh7.5 cells, and primary human fetal hepatocytes.


METHODS
The half-life of CXCL-8 mRNA was measured by use of real-time reverse-transcription polymerase chain reaction following tumor necrosis factor (TNF)- alpha induction in the presence and absence of inhibitors of transcription and translation. Cellular mRNAs containing AREs were assessed by custom microarray analyses.


RESULTS
The half-life of CXCL-8 mRNA increased in 3 of 4 HCV replicon cell lines, particularly after treatment with TNF- alpha , a potent inducer of CXCL-8. CXCL-8 mRNA was superinduced by TNF- alpha in the presence of the protein-synthesis inhibitor cycloheximide. Analysis of >1500 ARE-containing cellular mRNAs, by use of microarrays, revealed that CXCL-8 and other newly identified ARE genes were induced by TNF- alpha in Huh7 cells and were coordinately regulated.


CONCLUSIONS
The data suggest that increased CXCL-8 gene expression in the context of HCV replication involves posttranscriptional events.
Green
Jamison
J
Department of Laboratory Medicine, University of Washington, Seattle, 98104-2499, USA.
Khabar
Khalid S A
KS
Koo
Bon Chang A
BC
Williams
Bryan R G
BR
Polyak
Stephen J
SJ
D000225:Adenine / Q000378:metabolism; D002460:Cell Line; D019743:Chemokines, CXC / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D016174:Hepacivirus / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D016209:Interleukin-8; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism*; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014529:Uridine / Q000378:metabolism; D014779:Virus Replication
C457773:CXCL8(3-73)K11R,G31P, bovine; D019743:Chemokines, CXC; D016209:Interleukin-8; D010446:Peptide Fragments; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D000225:Adenine; D014529:Uridine