Retroviruses and primate evolution
ABSTRACT Human endogenous retroviruses (HERVs), probably representing footprints of ancient germ-cell retroviral infections, occupy about 1% of the human genome. HERVs can influence genome regulation through expression of retroviral genes, either via genomic rearrangements following HERV integrations or through the involvement of HERV LTRs in the regulation of gene expression. Some HERVs emerged in the genome over 30 MYr ago, while others have appeared rather recently, at about the time of hominid and ape lineages divergence. HERVs might have conferred antiviral resistance on early human ancestors, thus helping them to survive. Furthermore, newly integrated HERVs could have changed the pattern of gene expression and therefore played a significant role in the evolution and divergence of Hominoidea superfamily. Comparative analysis of HERVs, HERV LTRs, neighboring genes, and their regulatory interplay in the human and ape genomes will help us to understand the possible impact of HERVs on evolution and genome regulation in the primates. BioEssays 22:161-171, 2000.
- SourceAvailable from: Tatyana Vinogradova[Show abstract] [Hide abstract]
ABSTRACT: Insertion of LTRs into some genome locations might seriously affect regulation of the neighboring genes expression. This hypothesis is widely accepted but, however, not confirmed directly. Earlier, we have identified a family of closely related genes highly similar to the KIAA1245 mRNA counterpart. This family included a subfamily of genes some of which contained and the others lacked an LTR in their structure. We compared transcription of several closely related genes of the subfamily differing in the presence or absence of LTRs. Only LTR-containing genes were transcribed in transformed cell lines, tumorous and embryonic human tissues, whereas LTR-lacking genes remained silent. Since the genes were in the same intracellular microenvironment, we suggested that this effect was most probably due to intrinsic cis-characteristics of integrated LTRs and confirmed this by demonstrating high enhancer activity of KIAA1245 LTRs. The expression of the LTR-containing genes in embryonic tissues might suggest their involvement in evolutionary events during primate speciation.Virology 03/2007; 358(1):39-47. DOI:10.1016/j.virol.2006.06.027 · 3.28 Impact Factor
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ABSTRACT: Recently, a new HERV-T family, representative of the HERV-S71 and HERV-HC2 family, was identified using a screen for envelope genes and a computer-assisted database search. Here, we investigate expression of pol fragments of HERV-HC2 belonging to the HERV-T family in various human tissues and cancer cells. The pol gene was expressed in nearly all human tissues examined and in all cancer cell lines. Expression analyses suggest that the pol gene of HERV-HC2 family is more actively transcribed in human cancer cells than in normal tissues, suggesting a functional role during carcinogenesis. Phylogenetic analysis of the HERV-HC2 pol family revealed three groups (I, II, and III) generated through evolutionary divergence during primate evolution, indicating that they were integrated into primate genomes approximately 56 million years (MY) ago and have evolved at a rate of 0.2% nucleotide differences per MY. Our data might contribute to an understanding of the information on the transcriptional and pathological potential of the HERV-T family in human disease, including cancer.Journal of Human Genetics 02/2007; 52(4):285-96. DOI:10.1007/s10038-007-0115-8 · 2.53 Impact Factor
Article: Type I Interferons in Host Defense[Show abstract] [Hide abstract]
ABSTRACT: Type I interferons (IFNs) are a family of cytokines specialized to coordinate immunity to viruses and other intracellular infections. In the past several years, many of the receptors and signaling pathways that link pathogen detection to induction of type I IFNs have been identified and characterized. An integrated picture has emerged in which type I IFNs have essential functions in several seemingly disparate processes: they restrict viral spread by engaging machinery that ultimately cripples and kills infected cells, yet they are also positively linked to the activation and expansion of lymphocytes that are important for control of intracellular infections. These advances highlight the context-specific actions of type I IFNs and clarify the multiple points at which they are integrated into both innate and adaptive immunity.Immunity 10/2006; 25(3):373-81. DOI:10.1016/j.immuni.2006.08.007 · 19.75 Impact Factor