110 research outputs found
The JIL-1 kinase affects telomere expression in the different telomere domains of Drosophila
No full textIn Drosophila, the non-LTR retrotransposons HeT-A, TART and TAHRE build a head-to-tail array of repetitions that constitute the telomere domain by targeted transposition at the end of the chromosome whenever needed. As a consequence, Drosophila telomeres have the peculiarity to harbor the genes in charge of telomere elongation. Understanding telomere expression is important in Drosophila since telomere homeostasis depends in part on the expression of this genomic compartment. We have recently shown that the essential kinase JIL-1 is the first positive regulator of the telomere retrotransposons. JIL-1 mediates chromatin changes at the promoter of the HeT-A retrotransposon that are necessary to obtain wild type levels of expression of these telomere transposons. With the present study, we show how JIL-1 is also needed for the expression of a reporter gene embedded in the telomere domain. Our analysis, using different reporter lines from the telomere and subtelomere domains of different chromosomes, indicates that JIL-1 likely acts protecting the telomere domain from the spreading of repressive chromatin from the adjacent subtelomere domain. Moreover, the analysis of the 4R telomere suggests a slightly different chromatin structure at this telomere. In summary, our results strongly suggest that the action of JIL-1 depends on which telomere domain, which chromosome and which promoter is embedded in the telomere chromatin. © 2013 Silva-Sousa, Casacuberta.Peer Reviewe
The Chromosomal Proteins JIL-1 and Z4/Putzig Regulate the Telomeric Chromatin in Drosophila melanogaster
No full textDrosophila telomere maintenance depends on the transposition of the specialized retrotransposons HeT-A, TART, and TAHRE. Controlling the activation and silencing of these elements is crucial for a precise telomere function without compromising genomic integrity. Here we describe two chromosomal proteins, JIL-1 and Z4 (also known as Putzig), which are necessary for establishing a fine-tuned regulation of the transcription of the major component of Drosophila telomeres, the HeT-A retrotransposon, thus guaranteeing genome stability. We found that mutant alleles of JIL-1 have decreased HeT-A transcription, putting forward this kinase as the first positive regulator of telomere transcription in Drosophila described to date. We describe how the decrease in HeT-A transcription in JIL-1 alleles correlates with an increase in silencing chromatin marks such as H3K9me3 and HP1a at the HeT-A promoter. Moreover, we have detected that Z4 mutant alleles show moderate telomere instability, suggesting an important role of the JIL-1-Z4 complex in establishing and maintaining an appropriate chromatin environment at Drosophila telomeres. Interestingly, we have detected a biochemical interaction between Z4 and the HeT-A Gag protein, which could explain how the Z4-JIL-1 complex is targeted to the telomeres. Accordingly, we demonstrate that a phenotype of telomere instability similar to that observed for Z4 mutant alleles is found when the gene that encodes the HeT-A Gag protein is knocked down. We propose a model to explain the observed transcriptional and stability changes in relation to other heterochromatin components characteristic of Drosophila telomeres, such as HP1a. © 2012 Silva-Sousa et al.This work was supported by a grant from the Spanish Ministry of Science and Innovation BFU2009-08318/BMC to EC and by a PhD Fellowship from Fundação para a Ciência e Tecnologia, Portugal, SFRH/BD/36291/2007 to RS-S.Peer Reviewe
JIL-1 act as suppressor of TPE over the TAS domain.
No full text<p>(<b>A</b>) TPE assays in the TAS domain were performed with the reporter lines 39C-5 (chromosome 2L, TAS-L) and 39C-27 (chromosome 2R, TAS-R). No effect on the mini-white gene expression was observed when the reporter lines were crossed with the <i>JIL-1</i> heterozygous mutants <i>JIL-1</i><sup><i>z60</i></sup>/+ and <i>JIL-1</i><sup><i>h9</i></sup><i>/+</i> (2<sup>nd</sup> and 3<sup>rd</sup> column). However, when the same lines were crossed with the trans-heterozygous mutant allele (<i>JIL-1z60</i>/<i>JIL-1</i><sup><i>h9</i></sup>), a clear increase in the eye color was observed revealing a suppressor effect of JIL-1 over the TAS domain (4<sup>th</sup> column). 5<sup>th</sup> column: control cross of the TAS reporter lines with the <i>Su</i>(var)<i>2-5</i><sup><i>05</i></sup>, a HP1a mutant allele, does not show any differences in the expression of the mini-white gene inserted in TAS as expected by the literature (see main text). (<b>B</b>) Chromatin immunoprecipitation (ChIP) experiments reveal that the <i>JIL-1</i> trans-heterozygous mutant allele (<i>JIL-1z60</i>/<i>JIL-1</i><sup><i>h9)</i></sup> lead to a decrease in the presence of the H3K27me3 mark at the TAS domain. Three independent ChIP samples were analyzed and the amount of immunoprecipitated DNA was calculated by three independent quantitative real-time PCRs. Specific primers were used to quantify the amount of TAS or <i>HeT-A</i> DNA immunoprecipitated by the H3K27me3 antibody (see <i>M</i>&<i>M</i>).</p
The JIL-1 kinase affects telomere expression in the different telomere domains of Drosophila.
No full textIn Drosophila, the non-LTR retrotransposons HeT-A, TART and TAHRE build a head-to-tail array of repetitions that constitute the telomere domain by targeted transposition at the end of the chromosome whenever needed. As a consequence, Drosophila telomeres have the peculiarity to harbor the genes in charge of telomere elongation. Understanding telomere expression is important in Drosophila since telomere homeostasis depends in part on the expression of this genomic compartment. We have recently shown that the essential kinase JIL-1 is the first positive regulator of the telomere retrotransposons. JIL-1 mediates chromatin changes at the promoter of the HeT-A retrotransposon that are necessary to obtain wild type levels of expression of these telomere transposons. With the present study, we show how JIL-1 is also needed for the expression of a reporter gene embedded in the telomere domain. Our analysis, using different reporter lines from the telomere and subtelomere domains of different chromosomes, indicates that JIL-1 likely acts protecting the telomere domain from the spreading of repressive chromatin from the adjacent subtelomere domain. Moreover, the analysis of the 4R telomere suggests a slightly different chromatin structure at this telomere. In summary, our results strongly suggest that the action of JIL-1 depends on which telomere domain, which chromosome and which promoter is embedded in the telomere chromatin
JIL-1 affects the expression of genes embedded in the HTT array.
No full text<p>For all crosses, eyes from F1 males are shown. 1<sup>st</sup> column: control: F1 male descendants from crossing <i>w</i><sup>1118</sup> females with male flies with the indicated reporter line, 2<sup>nd</sup> and 3<sup>rd</sup> columns: results from the crosses of the <i>JIL-1</i> heterozygous, <i>JIL-1</i><sup><i>z60</i></sup>/+ or <i>JIL-1</i><sup><i>h9</i></sup><i>/+</i>, with the indicated reporter line. 4<sup>th</sup> column: Result from crossing the <i>JIL-1<sup>z60</sup>/JIL-1</i><sup><i>h9</i></sup> transheterozygous allele with the indicated <i>mini-white</i> insertion. The schematic drawings on the left indicate the position of the insertion (red arrow head) of the mini-white reporter gene in each of the reporter lines. Black circle represents telomere cap, white rectangle the telomeric retrotransposon array (HTT), light grey rectangle the subtelomeric domain TAS, telomere associated sequences, or TZ, transition zone, and dark grey rectangle represents the chromosome arm. EY08176 for the 2R telomere (1<sup>st</sup> row), EY09966 for the 4R telomere (2<sup>nd</sup> row), and EY00453 for the 3L telomere (3<sup>rd</sup> row). Note that descendants from the <i>JIL-1</i> heterozygous, <i>JIL-1</i><sup><i>z60</i></sup>/+ or <i>JIL-1</i><sup><i>h9</i></sup><i>/+</i>, show a subtle enhancer effect in the telomere line EY08176 (1<sup>st</sup> row) and no effect with the telomere line EY00453 (3<sup>rd</sup> row). We did not observe any effect in the EY09966 line corresponding to the 4R telomere, likely because the reporter gene is already heavily repressed in this line (2<sup>nd</sup> row). When the <i>JIL-1<sup>z60</sup>/JIL-1</i><sup><i>h9</i></sup> transheterozygous allele is assayed with the EY08176 reporter line, an enhancer effect of TPE is observed (4<sup>th</sup> column). </p
JIL-1 and HP1 control expression from the subtelomeric region of the fourth chromosome.
No full text<p>Reporter lines from the subtelomere domain (transition zone) of chromosome 4R, 39C-72 and 118E-5, were crossed with the heterozygous mutant alleles <i>JIL-1</i><sup><i>z60</i></sup>/+, <i>JIL-1</i><sup><i>h9</i></sup><i>/+</i> and <i>Su</i>(var)<i>2-5</i><sup><i>05</i></sup>. The subtelomere domain of the 4<sup>th</sup> chromosome shows a clear descent in eye color already with the simple <i>JIL-1</i> heterozygous alleles, (2<sup>nd</sup> and 3<sup>rd</sup> columns) and a strong suppressor effect of TPE in the <i>Su</i>(var)<i>2-5</i><sup><i>05</i></sup> allele (4<sup>th</sup> column). </p
The chromosomal proteins JIL-1 and Z4/Putzig regulate the telomeric chromatin in Drosophila melanogaster.
No full textDrosophila telomere maintenance depends on the transposition of the specialized retrotransposons HeT-A, TART, and TAHRE. Controlling the activation and silencing of these elements is crucial for a precise telomere function without compromising genomic integrity. Here we describe two chromosomal proteins, JIL-1 and Z4 (also known as Putzig), which are necessary for establishing a fine-tuned regulation of the transcription of the major component of Drosophila telomeres, the HeT-A retrotransposon, thus guaranteeing genome stability. We found that mutant alleles of JIL-1 have decreased HeT-A transcription, putting forward this kinase as the first positive regulator of telomere transcription in Drosophila described to date. We describe how the decrease in HeT-A transcription in JIL-1 alleles correlates with an increase in silencing chromatin marks such as H3K9me3 and HP1a at the HeT-A promoter. Moreover, we have detected that Z4 mutant alleles show moderate telomere instability, suggesting an important role of the JIL-1-Z4 complex in establishing and maintaining an appropriate chromatin environment at Drosophila telomeres. Interestingly, we have detected a biochemical interaction between Z4 and the HeT-A Gag protein, which could explain how the Z4-JIL-1 complex is targeted to the telomeres. Accordingly, we demonstrate that a phenotype of telomere instability similar to that observed for Z4 mutant alleles is found when the gene that encodes the HeT-A Gag protein is knocked down. We propose a model to explain the observed transcriptional and stability changes in relation to other heterochromatin components characteristic of Drosophila telomeres, such as HP1a
Possible scenarios for the TAS and the HTT chromatin in a <i>JIL-1</i> mutant background.
No full text<p>(<b>A</b>) Wild type: the presence of the H3K27me3 mark nucleates a highly repressed chromatin (note the tight packaging of the nucleosomes) in the TAS domain, regulated by the Polycomb group of proteins (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0081543#pone.0081543.s002" target="_blank">Table S1</a>). (<b>B</b>) <i>JIL-1</i> mutant background: The loss of the JIL-1 boundary, causes a spread of the H3K27me3 mark into the HTT array, resulting in a local decrease of the H3K27me3 mark in the TAS chromatin and as a consequence making this compartment more permissive to gene expression.</p
Using Teaching Faculty Focus Groups to Assess Information Literacy Core Competencies at University Level
No full textGrand Valley State University librarians designed and conducted teaching faculty1 focus groups to gauge their response to a new information literacy (IL) core student competencies document created to support a developing library IL programme. Although the competencies were inspired by existing, widely known information literacy standards and guidelines the University Libraries’ Information Literacy Competencies document (ILCC) is unique and written specifically to address the university’s culture and curriculum. The authors of this paper formed a research team to assemble two groups of teaching faculty from various disciplines and to analyse focus group transcripts using a content analysis approach. The resulting data revealed unexpected perceptions about information literacy among teaching faculty and concerns about how to apply the ILCC document. In analysing the data, we generated ideas for supporting teaching faculty as they apply the ILCC document. Focus groups were used to gauge teaching faculty perceptions of the ILCC document. The results of the focus groups informed our efforts to tailor the ILCC document to existing university programs and curricula by using the language that was familiar to teaching faculty; and to explore teaching faculty perceptions of challenges and needed support. The paper explains how the focus group method was employed to test information literacy competencies in order to provide a potential model for other universities who are customising their own information literacy standards
Z4 interacts with JIL-1 and <i>HeT-A</i> GAG.
No full text<p>(A) Z4 and JIL-1 immunoprecipitation was performed in S2 cells using anti-JIL-1 and anti-Z4 antibodies. Negative control experiments were performed by immunoprecipitating with unspecific IgGs. (B) Z4 and <i>HeT-A</i> GAG immunoprecipitation was done by transfecting S2 cells with HeT-A Gag-GFP and immunoprecipitating with αnti-GFP and αnti-Z4. Control experiments were performed by transfecting an empty GFP vector (pPL17). Presence of the recombinant protein is indicated on the top of the panel (+ and − symbols). Antibodies used for immunoprecipitation are indicated on the top. All extracts were fractionated by SDS-PAGE, western blotted, and developed with specific antibodies (indicated on the right of each figure). Molecular markers (kDa) are indicated on the left.</p
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