The 5' untranslated region of the I factor, a long interspersed nuclear element-like retrotransposon of Drosophila melanogaster, contains an internal promoter and sequences that regulate expression.

McLean, Colin; Bucheton, Alain; Finnegan, David J.

doi:10.1128/mcb.13.2.1042

Cited by 84 publications

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“…In each case, at least part of the regulation is exerted at the level of transcription since full length I factor transcripts can be detected by Northern blots only in RNA from the ovaries of SF and RSF females (5). The promoter that directs synthesis of this RNA is located within the first 30 bp of the I factor (10). A reporter gene linked to the first 186 nucleotides of the I factor, the 5Ј-untranslated region (5Ј-UTR), is expressed to a level that is Ϸ20-fold higher in ovaries than in nonovarian tissues because of an ovary specific enhancer between nucleotides 41 and 186 (11).…”

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confidence: 99%

Copy number control of a transposable element, the I factor, a LINE-like element in Drosophila

Chaboissier

Bucheton

Finnegan

1998

Proc. Natl. Acad. Sci. U.S.A.

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The I factor is a LINE-like transposable element in Drosophila. Most strains of Drosophila melanogaster, inducer strains, contain 10-15 copies of the I factor per haploid genome located in the euchromatic regions of the chromosome arms. These are not present in a few strains known as reactive strains. I factors transpose at low frequency in inducer strains but at high frequency in the female progeny of crosses between reactive and inducer f lies. We have found that the activity of the I factor promoter is sensitive to the number of copies of the first 186 nucleotides of the I factor sequence, which constitutes the 5-untranslated region. The activity of the I factor decreases as the copy number of this sequence increases.Transposable elements are a substantial component of eukaryotic genomes, often making up Ͼ15% of the total DNA. There is probably strong selection for mechanisms that limit the frequency with which these elements transpose as transposition leads to an increase in the number of copies of an element and can cause insertional mutations and gross chromosome rearrangements. The mechanisms that restrict transposition are understood poorly, although they include element encoded regulatory molecules (1) and interactions between elements and the products of host genes (2). The I factor is a non-long terminal repeat, or LINE-like, retrotransposon (3). Like other elements of this type, it has no terminal repeats but possesses a deoxyadenosine-rich sequence at the 3Ј end of one strand and has two ORFs, the first encoding a nucleic acid binding protein and the second a putative reverse transcriptase (3, 4). To transpose, the I factor is transcribed into a full length RNA that is reverse transcribed into a copy integrated at a new site in the genome (5-7).All strains of Drosophila melanogaster studied so far contain 20-30 defective I factors per haploid genome located in pericentromeric DNA. The majority of strains, the so-called inducer strains, also contain 10-15 I factors in the euchromatic DNA of the chromosome arms. These include full length functional elements. A few strains lack these active elements and are known as reactive strains (8). The frequency of transposition of I factors in inducer strains is low but is increased by several orders of magnitude in the female progeny of crosses between reactive females and inducer males (9). This increase is not seen in the male progeny of such a cross and in females appears to be confined to the germ line, where it is associated with reduced fertility and an increased mutation rate. This phenomenon is called I-R hybrid dysgenesis, and the affected females are called SF females. The female progeny of reciprocal crosses, RSF females, appear normal, although the frequency of I factor transposition is increased in their germline and is only approximately five times less than in SF females (9).These observations suggest that I factors are subject to at least two forms of regulation, one that prevents transposition in inducer strains but permits transpositio...

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Copy number control of a transposable element, the I factor, a LINE-like element in Drosophila

Chaboissier

Bucheton

Finnegan

1998

Proc. Natl. Acad. Sci. U.S.A.

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“…For LINEs, only a few cases in which regulatory elements mediate tissue-specific expression in vivo are known. The I factor is one example: a specific regulatory element directing ovary-specific expression could be isolated in the 5Ј untranslated leader region (28,32).…”

Section: Discussionmentioning

confidence: 99%

“…The role of LINEs in genome evolution and potentially also in genome organization is only poorly understood. Some of the LINEs have been shown to be active in a tissue-specific manner during mammalian and Drosophila development (28,32,47). However, apart from the knowledge about their expression domains, not much is known about whether the gene products of these elements also have a function in developmental processes.…”

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Germ Line and Embryonic Expression of Fex, a Member of the Drosophila F-Element Retrotransposon Family, Is Mediated by an Internal cis-Regulatory Control Region

Kerber

Fellert

Taubert

et al. 1996

Molecular and Cellular Biology

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The F elements of Drosophila melanogaster belong to the superfamily of long interspersed nucleotide element retrotransposons. To date, F-element transcription has not been detected in flies. Here we describe the isolation of a member of the F-element family, termed Fex, which is transcribed in specific cells of the female and male germ lines and in various tissues during embryogenesis of D. melanogaster. Sequence analysis revealed that this element contains two complete open reading frames coding for a putative nucleic acidbinding protein and a putative reverse transcriptase. Functional analysis of the 5 region, using germ line transformation of Fex-lacZ reporter gene constructs, demonstrates that major aspects of tissue-specific Fex expression are controlled by internal cis-acting elements that lie in the putative coding region of open reading frame 1. These sequences mediate dynamic gene expression in eight expression domains during embryonic and germ line development. The capacity of the cis-regulatory region of the Fex element to mediate such complex expression patterns is unique among members of the long interspersed nucleotide element superfamily of retrotransposons and is reminiscent of regulatory regions of developmental control genes.

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“…These elements, also known as viral retrotransposons, resemble the integrated genomes of retroviruses as they carry LTRs. LINEs lack LTRs, and their expression is controlled by promoters which are located within the transcribed region Swergold, 1990;Minchiotti and Di Nocera, 1991;Minakami et al, 1992;Contursi et al, 1993;McLean et al, 1993).By means of transient transfection assays we monitored the expression of constructs in which the reporter CAT gene was under the control of various Doc DNA segments in Drosophila Schneider II (S2) cells. We show that distinct cis-acting DNA elements, clustered in a ϳ50-bp long DNA region located at the 5Ј end of unit-length Doc copies, cooperate to control RNA initiation.…”

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Identification of Sequences Which Regulate the Expression of Drosophila melanogaster Doc Elements

Contursi

Minchiotti

Nocera

1995

Journal of Biological Chemistry

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Doc is one of 50 or more mobile DNA elements that have been identified in the fruit fly Drosophila melanogaster . Doc elements lack terminal repeats, instead terminating at the 3Ј end in runs of adenine residues flanked by polyadenylation signals. They differ in size, being variously truncated at the 5Ј end, and are flanked by target site duplications which vary in length from 10 to 14 bp 1 (Schneuwly et al., 1987;Driver et al., 1989). Complete family members are ϳ4.7 kb in length and potentially encode a putative nucleic acid binding protein and a reverse transcriptase (O'Hare et al., 1991). The structure and coding capacity of Doc is typical of LINEs, nomadic DNA sequences conserved in evolution from protozoa to man (Doolittle et al., 1989;Xiong and Eickbush, 1990). LINEs, also known as type II retrotransposons, use self-encoded proteins to reverse transcribe their own mRNA and integrate cDNA copies at new locations in the genome. This hypothesis has been experimentally supported by the analysis of transgenic flies carrying intron-marked Drosophila I factors (Pelisson et al., 1991;Jensen and Heidmann, 1991) and baby hamster kidney cells transfected with mouse LINE-1 elements (Evans and Palmiter, 1991).Mammalian genomes harbor Ͼ10 5 LINEs that belong to a single superfamily (Singer and Skowronski, 1985;Hutchison et al., 1989). By contrast, distinct LINE families, each including 50 -80 members, coexist in D. melanogaster. In addition to Doc, six other families of LINE elements have been described so far in this organism, including the I factor ), F (Di Nocera and Casari, 1987), G (Di Nocera, 1988, and jockey (Priimagi et al., 1988) elements, and type I and type II ribosomal DNA insertions (Jacubczak et al., 1990).LINEs differ markedly from other mobile DNA sequences that also propagate by the retrotranscription of RNA intermediates such as copia-like elements in D. melanogaster ) and the Ty element (Boeke et al., 1985) in Saccharomyces cerevisiae. These elements, also known as viral retrotransposons, resemble the integrated genomes of retroviruses as they carry LTRs. LINEs lack LTRs, and their expression is controlled by promoters which are located within the transcribed region Swergold, 1990;Minchiotti and Di Nocera, 1991;Minakami et al., 1992;Contursi et al., 1993;McLean et al., 1993).By means of transient transfection assays we monitored the expression of constructs in which the reporter CAT gene was under the control of various Doc DNA segments in Drosophila Schneider II (S2) cells. We show that distinct cis-acting DNA elements, clustered in a ϳ50-bp long DNA region located at the 5Ј end of unit-length Doc copies, cooperate to control RNA initiation. In addition, we found that sequences located ϳ200 bp downstream from the 5Ј end inhibit the expression of the reporter CAT gene in a position-and orientation-dependent manner. The inhibition appears to be due to reduced translation rather than to impaired synthesis of CAT mRNA. clones suN, 6N, and 11N, in which the 5Ј end regions of the elements su(f) S2 , Doc6...

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The 5' untranslated region of the I factor, a long interspersed nuclear element-like retrotransposon of Drosophila melanogaster, contains an internal promoter and sequences that regulate expression.

Cited by 84 publications

References 67 publications

Copy number control of a transposable element, the I factor, a LINE-like element in Drosophila

Copy number control of a transposable element, the I factor, a LINE-like element in Drosophila

Germ Line and Embryonic Expression of Fex, a Member of the Drosophila F-Element Retrotransposon Family, Is Mediated by an Internal cis-Regulatory Control Region

Identification of Sequences Which Regulate the Expression of Drosophila melanogaster Doc Elements

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