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Expression studies of the core+1 protein of the hepatitis C virus 1a in mammalian cells
Author(s) -
Vassilaki Niki,
Boleti Haralabia,
Mavromara Penelope
Publication year - 2007
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2007.05929.x
Subject(s) - biology , open reading frame , cytoplasm , endoplasmic reticulum , hbcag , microbiology and biotechnology , protein biosynthesis , hepatitis c virus , transfection , virology , translation (biology) , virus , gene , messenger rna , hepatitis b virus , peptide sequence , genetics , hbsag
Recent studies have suggested the existence of a novel protein of hepatitis C virus (HCV) encoded by an ORF overlapping the core gene in the +1 frame (core+1 ORF). Two alternative translation mechanisms have been proposed for expression of the core+1 ORF of HCV‐1a in cultured cells; a frameshift mechanism within codons 8–11, yielding a protein known as core+1/F, and/or translation initiation from internal codons in the core+1 ORF, yielding a shorter protein known as core+1/S. To date, the main evidence for the expression of this protein in vivo has been the specific humoral and cellular immune responses against the protein in HCV‐infected patients, inasmuch as its detection in biopsies or the HCV infectious system remains elusive. In this study, we characterized the expression properties of the HCV‐1a core+1 protein in mammalian cells in order to identify conditions that facilitate its detection. We showed that core+1/S is a very unstable protein, and that expression of the core protein in addition to proteosome activity can downregulate its intracellular levels. Also, we showed that in the Huh‐7/T7 cytoplasmic expression system the core+1 ORF from the HCV‐1 isolate supports the synthesis of both the core+1/S and core+1/F proteins. Finally, immunofluorescence and subcellular fractionation analyses indicated that core+1/S and core+1/F are cytoplasmic proteins with partial endoplasmic reticulum distribution in interphase cells, whereas in dividing cells they also localize to the microtubules of the mitotic spindle.