R region sequences in the long terminal repeat of a murine retrovirus specifically increase expression of unspliced RNAs

Alla M. Trubetskoy, Sharon A. Okenquist, Jack Lenz

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

A stem-loop structure at the 5' end of the R region of the long terminal repeat (LTR) of the murine leukemia virus SL3 and other type C mammalian retroviruses is important for maximum levels of expression of a reporter gene under the control of the vital LTR. This element, termed the R region stem- loop (RSL), has a small effect on transcriptional initiation and no effect on RNA polymerase processivity. Its major effect is on posttranscriptional processing of LTR-driven transcripts. Here we tested whether the RSL affected the production of RNAs from a full-length SL3 genome. Mutation of the RSL in the 5' LTR of SL3 reduced the cytoplasmic levels of full-length vital transcripts but not those of spliced, env mRNA transcripts. Thus, the RSL specifically affected the cytoplasmic levels of the unspliced vital RNA. To test further whether the effect was specific for unspliced transcripts, a system was devised in which the expression of a reporter gene under the control of the vital LTR was tested in the presence or absence of an intron. Mutation of the RSL resulted in only about a twofold decline in the level of reporter gene expression when the transcripts contained an intron. However, when the intron was removed, mutation of the RSL reduced expression of the reporter gene about 10-to 60-fold in various cell lines. The secondary structure of the RSL was essential for its activity on the intronless transcript. Thus, the RSL appears to be important for the cytoplasmic accumulation of unspliced vital RNA and unspliced RNA from chimeric transcription units under the control of the vital LTR.

Original languageEnglish (US)
Pages (from-to)3477-3483
Number of pages7
JournalJournal of Virology
Volume73
Issue number4
StatePublished - Apr 1999

Fingerprint

Retroviridae
terminal repeat sequences
Terminal Repeat Sequences
RNA
Reporter Genes
stems
mice
Introns
reporter genes
Mutation
introns
Gammaretrovirus
mutation
Murine Leukemia Viruses
DNA-Directed RNA Polymerases
Murine leukemia virus
Genome
DNA-directed RNA polymerase
Gene Expression
Cell Line

ASJC Scopus subject areas

  • Immunology

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R region sequences in the long terminal repeat of a murine retrovirus specifically increase expression of unspliced RNAs. / Trubetskoy, Alla M.; Okenquist, Sharon A.; Lenz, Jack.

In: Journal of Virology, Vol. 73, No. 4, 04.1999, p. 3477-3483.

Research output: Contribution to journalArticle

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