The hepatitis B virus PRE contains a splicing regulatory element.
The posttranscriptional regulatory element (PRE) is considered to enhance hepatitis B virus (HBV) gene expression by facilitating the nuclear export of intronless viral subgenomic RNAs. Its role in the RNA metabolism of the viral pregenomic RNA (pgRNA) is currently unknown. We identified a positively cis-acting splicing regulatory element (SRE-1) and present two lines of evidence for its functionality. Firstly, in a heterologous context SRE-1 functionally substitutes for a retroviral bidirectional exonic splicing enhancer (ESE). As expected, SRE-1 is a splicing enhancer also in its natural viral sequence context, since deletion of SRE-1 reduces splicing of pgRNA in cell culture experiments. Secondly, we show that stimulation of HBV RNA splicing by the splicing factor PSF was repressed by the PRE. Analysis of a variety of PSF mutants indicated that RNA-binding and protein-protein interaction were required to enhance splicing. In addition, we show that the PRE contributed to pgRNA stability, but has little influence on its nuclear export. Herein, we report for the first time that the PRE harbors splicing stimulating and inhibiting regulatory elements controlling processing of the viral pregenome. We discuss a model in which the regulation of pgRNA splicing depends on cellular factors interacting with the PRE.
Heise
Tilman
T
Heinrich-Pette-Institut für Experimentelle Virologie und Immunologie an der Universität Hamburg, Martinistrasse 52, D-20251 Hamburg, Germany. heise@hpi.uni-hamburg.de
Sommer
Gunhild
G
Reumann
Kerstin
K
Meyer
Imke
I
Will
Hans
H
Schaal
Heiner
H
D045744:Cell Line, Tumor; D015967:Gene Expression Regulation, Viral; D006515:Hepatitis B virus / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D000072670:PTB-Associated Splicing Factor; D012326:RNA Splicing; D012367:RNA, Viral / Q000737:chemistry* / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism; D038621:Regulatory Sequences, Ribonucleic Acid
D000072670:PTB-Associated Splicing Factor; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D038621:Regulatory Sequences, Ribonucleic Acid