Important note: Information in this article was accurate in 1992. The state of the art may have changed since the publication date.
POSITIVE AND NEGATIVE REGULATION OF HUMAN T-CELL LEUKEMIA VIRUS TYPE I (HTLV-I) GENE EXPRESSION AND REPLICATION: FUNCTION OF THE REX GENE
The Human Retroviruses. Gallo RC and Jay G, eds. San Diego, Academic Press, p. 3-20, 1991.. Unique Identifier : AIDSLINE ICDB/92678719 Yoshida M; Inoue J; Fujisawa J; Dept. of Cellular and Molecular Biology, Inst. of Medical; Science, Univ. of Tokyo, Tokyo 108, Japan
Abstract:
HTLV-I is a retrovirus, but is classified in a unique group distinct from the general onco-retroviruses. The genome contains an extra sequence named 'pX' in addition to the gag, pol, and env genes. The Px region contains three overlapping genes, tax, rex, and a third that codes for p21, whose function is not yet known. Expression of the HTLV-I genes is regulated at two different levels, transcription and RNA processing, by a combination of tax and rex functions. The tax and rex genes in combination regulated HTLV-I gene expression and replication in both positive and negative ways. Recent findings concerning rex gene function are reviewed and the significance of these results to viral replication and adult T-cell leukemia development are discussed. Topics include discovery of the rex gene function; regulation of expression of gag, pol, and env genes; two cis-acting elements of rex function; mode of action of the rex protein; cross-reaction of the rex protein on HIV RNA; and secondary structure of the rex-responsive element. The Rex protein functions in cytoplasmic expression of unspliced RNA, that is, Gag/Pol and Env mRNAs encoding virion proteins for maturation of viral particles. However, this Rex function has more significance in regulation of viral gene expression and in survival under the pressure of the host immune response. The regulatory system that is activated by enhancement of transcriptional initiation and repressed by modulation of RNA processing seems to be a unique mode of regulation of gene expression. However, most viral functions are similar to certain cellular events. Thus, gene regulation mediated by Rex protein through RNA processing might have a cellular equivalent. Such a system could provide a new strategy for studying gene regulation at the level of RNA processing. (65 Refs)
Keywords: Base Sequence/GENETICS Gene Expression Regulation, Viral/*PHYSIOLOGY Genes, env/GENETICS/PHYSIOLOGY Genes, gag/GENETICS/PHYSIOLOGY Genes, pol/GENETICS/PHYSIOLOGY Genes, pX/*GENETICS/PHYSIOLOGY Human HIV/GENETICS HTLV-I/*GENETICS/PATHOGENICITY Leukemia-Lymphoma, T-Cell, Acute, HTLV-I-Associated/*GENETICS/ MICROBIOLOGY Molecular Sequence Data RNA, Viral/GENETICS Transcription Factors/GENETICS/PHYSIOLOGY Virus Replication/*GENETICS MONOGRAPH REVIEW
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Important note: Information in this article was accurate in 1992. The state of the art may have changed since the publication date.
