Gene codon composition determines differentiation-dependent expression of a viral capsid gene in keratinocytes in vitro and in vivo.
By establishing mouse primary keratinocytes (KCs) in culture, we were able, for the first time, to express papillomavirus major capsid (L1) proteins by transient transfection of authentic or codon-modified L1 gene expression plasmids. We demonstrate in vitro and in vivo that gene codon composition is in part responsible for differentiation-dependent expression of L1 protein in KCs. L1 mRNA was present in similar amounts in differentiated and undifferentiated KCs transfected with authentic or codon-modified L1 genes and had a similar half-life, demonstrating that L1 protein production is posttranscriptionally regulated. We demonstrate further that KCs substantially change their tRNA profiles upon differentiation. Aminoacyl-tRNAs from differentiated KCs but not undifferentiated KCs enhanced the translation of authentic L1 mRNA, suggesting that differentiation-associated change to tRNA profiles enhances L1 expression in differentiated KCs. Thus, our data reveal a novel mechanism for regulation of gene expression utilized by a virus to direct viral capsid protein expression to the site of virion assembly in mature KCs. Analysis of two structural proteins of KCs, involucrin and keratin 14, suggests that translation of their mRNAs is also regulated, in association with KC differentiation in vitro, by a similar mechanism.
Zhao
Kong-Nan
KN
Centre for Immunology and Cancer Research, The University of Queensland, Research Extension, Building 1, Princess Alexandra Hospital, Ipswich Road, Woolloongabba, Queensland 4102, Australia. knzhao@cicr.uq.edu.au
Gu
WenYi
W
Fang
Ning Xia
NX
Saunders
Nicholas A
NA
Frazer
Ian H
IH
D000818:Animals; D019470:Biolistics; D015152:Blotting, Northern; D015153:Blotting, Western; D002213:Capsid / Q000737:chemistry*; D002454:Cell Differentiation; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D003062:Codon; D004247:DNA / Q000378:metabolism; D003609:Dactinomycin / Q000494:pharmacology; D015967:Gene Expression Regulation, Viral; D066298:In Vitro Techniques; D053547:Keratin-14; D015603:Keratinocytes / Q000166:cytology* / Q000821:virology*; D007633:Keratins / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008856:Microscopy, Fluorescence; D009693:Nucleic Acid Hybridization; D027383:Papillomaviridae / Q000235:genetics; D010957:Plasmids / Q000378:metabolism; D014176:Protein Biosynthesis; D011498:Protein Precursors / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012343:RNA, Transfer / Q000737:chemistry / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014162:Transfection; D014780:Viruses / Q000378:metabolism*
D003062:Codon; C507540:KRT14 protein, human; D053547:Keratin-14; C507446:Krt14 protein, mouse; D011498:Protein Precursors; D012333:RNA, Messenger; D003609:Dactinomycin; C032253:involucrin; D012313:RNA; D007633:Keratins; D004247:DNA; D012343:RNA, Transfer