scholarly journals The Drosophila Dosage Compensation Complex activates target genes by chromosome looping within the active compartment

2017 ◽  
Author(s):  
Tamás Schauer ◽  
Yad Ghavi-Helm ◽  
Tom Sexton ◽  
Christian Albig ◽  
Catherine Regnard ◽  
...  
Keyword(s):  
Dosage Compensation ◽  
Target Genes ◽  
De Novo ◽  
Gene Activation ◽  
Nuclear Architecture ◽  
Dosage Compensation Complex ◽  
Chromosome Conformation ◽  
X Chromosomes ◽  
Male Specific ◽  
Lethal Dosage

AbstractX chromosome dosage compensation in Drosophila requires chromosome-wide coordination of gene activation. The male-specific-lethal dosage compensation complex (DCC) identifies X chromosomal High Affinity Sites (HAS) from which it boosts transcription. A sub-class of HAS, PionX sites, represent first contacts on the X. Here, we explored the chromosomal interactions of representative PionX sites by high-resolution 4C and determined the global chromosome conformation by Hi-C in sex-sorted embryos. Male and female X chromosomes display similar nuclear architecture, concordant with clustered, constitutively active genes. PionX sites, like HAS, are evenly distributed in the active compartment and engage in short- and long-range interactions beyond compartment boundaries. By de novo induction of DCC in female cells, we monitored the extent of activation surrounding PionX sites. This revealed a remarkable range of DCC action not only in linear proximity, but also at megabase distance if close in space, suggesting that DCC profits from pre-existing chromosome folding to activate genes.

scholarly journals Absence of X-chromosome dosage compensation in the primordial germ cells of Drosophila embryos

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ryoma Ota ◽  
Makoto Hayashi ◽  
Shumpei Morita ◽  
Hiroki Miura ◽  
Satoru Kobayashi
Keyword(s):  
X Chromosome ◽  
Germ Cells ◽  
Dosage Compensation ◽  
Sex Chromosome ◽  
Primordial Germ Cells ◽  
Histone H4 ◽  
X Chromosomes ◽  
Essential Components ◽  
Msl Complex ◽  
Male Specific

AbstractDosage compensation is a mechanism that equalizes sex chromosome gene expression between the sexes. In Drosophila, individuals with two X chromosomes (XX) become female, whereas males have one X chromosome (XY). In males, dosage compensation of the X chromosome in the soma is achieved by five proteins and two non-coding RNAs, which assemble into the male-specific lethal (MSL) complex to upregulate X-linked genes twofold. By contrast, it remains unclear whether dosage compensation occurs in the germline. To address this issue, we performed transcriptome analysis of male and female primordial germ cells (PGCs). We found that the expression levels of X-linked genes were approximately twofold higher in female PGCs than in male PGCs. Acetylation of lysine residue 16 on histone H4 (H4K16ac), which is catalyzed by the MSL complex, was undetectable in these cells. In male PGCs, hyperactivation of X-linked genes and H4K16ac were induced by overexpression of the essential components of the MSL complex, which were expressed at very low levels in PGCs. Together, these findings indicate that failure of MSL complex formation results in the absence of X-chromosome dosage compensation in male PGCs.

scholarly journals Contingency in the convergent evolution of a regulatory network: Dosage compensation in Drosophila

2018 ◽  
Author(s):  
Doris Bachtrog ◽  
Chris Ellison
Keyword(s):  
Transposable Element ◽  
Dosage Compensation ◽  
Sex Chromosomes ◽  
Binding Sites ◽  
Evolutionary Biology ◽  
De Novo ◽  
Binding Motif ◽  
Sequence Motif ◽  
X Chromosomes ◽  
Msl Complex

The repeatability or predictability of evolution is a central question in evolutionary biology, and most often addressed in experimental evolution studies. Here, we infer how genetically heterogeneous natural systems acquire the same molecular changes, to address how genomic background affects adaptation in natural populations. In particular, we take advantage of independently formed neo-sex chromosomes in Drosophila species that have evolved dosage compensation by co-opting the dosage compensation (MSL) complex, to study the mutational paths that have led to the acquisition of 100s of novel binding sites for the MSL complex in different species. This complex recognizes a conserved 21-bp GA-rich sequence motif that is enriched on the X chromosome, and newly formed X chromosomes recruit the MSL complex by de novo acquisition of this binding motif. We identify recently formed sex chromosomes in the Drosophila repleta and robusta species groups by genome sequencing, and generate genomic occupancy maps of the MSL complex to infer the location of novel binding sites. We find that diverse mutational paths were utilized in each species to evolve 100s of de novo binding motifs along the neo-X, including expansions of microsatellites and transposable element insertions. However, the propensity to utilize a particular mutational path differs between independently formed X chromosomes, and appears to be contingent on genomic properties of that species, such as simple repeat or transposable element density. This establishes the “genomic environment” as an important determinant in predicting the outcome of evolutionary adaptations.

scholarly journals GA-repeats on mammalian X chromosomes support Ohno’s hypothesis of dosage compensation by transcriptional upregulation

2018 ◽  
Author(s):  
Edridge D’Souza ◽  
Elizaveta Hosage ◽  
Kathryn Weinand ◽  
Steve Gisselbrecht ◽  
Vicky Markstein ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transposable Elements ◽  
X Chromosome ◽  
Dosage Compensation ◽  
Binding Sites ◽  
Convergent Evolution ◽  
Fruit Fly ◽  
Dosage Compensation Complex ◽  
X Chromosomes ◽  
Repeat Sequences

ABSTRACTOver 50 years ago, Susumo Ohno proposed that dosage compensation in mammals would require upregulation of gene expression on the single active X chromosome, a mechanism which to date is best understood in the fruit fly Drosophila melanogaster. Here, we report that the GA-repeat sequences that recruit the conserved MSL dosage compensation complex to the Drosophila X chromosome are also enriched across mammalian X chromosomes, providing genomic support for the Ohno hypothesis. We show that mammalian GA-repeats derive in part from transposable elements, suggesting a mechanism whereby unrelated X chromosomes from dipterans to mammals accumulate binding sites for the MSL dosage compensation complex through convergent evolution, driven by their propensity to accumulate transposable elements.

scholarly journals RNA Binding Protein Sex-Lethal (Sxl) and Control of Drosophila Sex Determination and Dosage Compensation

2003 ◽  
Vol 67 (3) ◽  
pp. 343-359 ◽  
Author(s):  
Luiz O. F. Penalva ◽  
Lucas Sánchez
Keyword(s):  
Sex Determination ◽  
Dosage Compensation ◽  
Target Genes ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Regulatory Gene ◽  
Sex Lethal ◽  
Male Specific ◽  
Regulatory Functions ◽  
And Control

SUMMARY In the past two decades, scientists have elucidated the molecular mechanisms behind Drosophila sex determination and dosage compensation. These two processes are controlled essentially by two different sets of genes, which have in common a master regulatory gene, Sex-lethal (Sxl). Sxl encodes one of the best-characterized members of the family of RNA binding proteins. The analysis of different mechanisms involved in the regulation of the three identified Sxl target genes (Sex-lethal itself, transformer, and male specific lethal-2) has contributed to a better understanding of translation repression, as well as constitutive and alternative splicing. Studies using the Drosophila system have identified the features of the protein that contribute to its target specificity and regulatory functions. In this article, we review the existing data concerning Sxl protein, its biological functions, and the regulation of its target genes.

scholarly journals Clustered DNA motifs mark X chromosomes for repression by a dosage compensation complex

Nature ◽  
2006 ◽  
Vol 444 (7119) ◽  
pp. 614-618 ◽  
Author(s):  
Patrick McDonel ◽  
Judith Jans ◽  
Brant K. Peterson ◽  
Barbara J. Meyer
Keyword(s):  
Dosage Compensation ◽  
Dosage Compensation Complex ◽  
X Chromosomes ◽  
Dna Motifs

scholarly journals The Caenorhabditis elegans Dosage Compensation Machinery Is Recruited to X Chromosome DNA Attached to an Autosome

Genetics ◽  
2000 ◽  
Vol 156 (4) ◽  
pp. 1603-1621
Author(s):  
Jason D Lieb ◽  
Carlos Ortiz de Solorzano ◽  
Enrique Garcia Rodriguez ◽  
Arthur Jones ◽  
Michael Angelo ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
X Chromosome ◽  
Dosage Compensation ◽  
Dna Sequences ◽  
Three Dimensional ◽  
Dosage Compensation Complex ◽  
X Chromosomes ◽  
Cis Acting ◽  
Recognition Elements ◽  
The Right

Abstract The dosage compensation machinery of Caenorhabditis elegans is targeted specifically to the X chromosomes of hermaphrodites (XX) to reduce gene expression by half. Many of the trans-acting factors that direct the dosage compensation machinery to X have been identified, but none of the proposed cis-acting X chromosome-recognition elements needed to recruit dosage compensation components have been found. To study X chromosome recognition, we explored whether portions of an X chromosome attached to an autosome are competent to bind the C. elegans dosage compensation complex (DCC). To do so, we devised a three-dimensional in situ approach that allowed us to compare the volume, position, and number of chromosomal and subchromosomal bodies bound by the dosage compensation machinery in wild-type XX nuclei and XX nuclei carrying an X duplication. The dosage compensation complex was found to associate with a duplication of the right 30% of X, but the complex did not spread onto adjacent autosomal sequences. This result indicates that all the information required to specify X chromosome identity resides on the duplication and that the dosage compensation machinery can localize to a site distinct from the full-length hermaphrodite X chromosome. In contrast, smaller duplications of other regions of X appeared to not support localization of the DCC. In a separate effort to identify cis-acting X recognition elements, we used a computational approach to analyze genomic DNA sequences for the presence of short motifs that were abundant and overrepresented on X relative to autosomes. Fourteen families of X-enriched motifs were discovered and mapped onto the X chromosome.

scholarly journals Interactions between dosage compensation complex components Msl-1, Msl-2 and NURF component NURF301 with long non-coding RNA gene hsrω

2019 ◽  
Author(s):  
Deo Prakash Chaturvedi
Keyword(s):  
X Chromosome ◽  
Dosage Compensation ◽  
Dosage Compensation Complex ◽  
Chromatin Remodeler ◽  
Down Regulation ◽  
Over Expression ◽  
Non Coding Rna ◽  
Crucial Component ◽  
Male Specific ◽  
Long Non Coding Rna

AbstractHyperactivity of the single X-chromosome in male Drosophila is achieved by establishing a ribonucleoprotein complex, called Dosage Compensation Complex (DCC), on the male X chromosome. Msl-1 and Msl-2 proteins, involved in the initiation and establishing of DCC on male X chromosome, are very crucial component of this complex. In the present study, it has been found here that a long non-coding RNA gene hsrω genetically interacts with Msl-1 as well as Msl-2 and suppresses the lethal phenotype of Msl-1 or Msl-2 down-regulation in its up-regulated background. Additionally, it is also found here that an ATP-dependent chromatin remodeler, NURF301, also interacts with hsrω in same manner. General lethality caused by Act-GAL4 driven global expression of NURF301-RNAi and the male-specific lethality following Msl-1-RNAi or Msl-2-RNAi transgene expression were partially suppressed by over-expression of hsrω, but not by down regulation through hsrω-RNAi. Likewise, eye phenotypes following ey-GAL4 driven down-regulation of NURF301 or Msl-1 or Msl-2 were also partially suppressed by over-expression of hsrω. Act-GAL4 driven global over-expression of hsrω along with Msl-1-RNAi or Msl-2-RNAi transgene substantially restored levels of MSL-2 protein on the male X chromosome. Similarly, levels and distribution of Megator protein, which was reduced and distribution at nuclear rim and in nucleoplasm was affected in the MT and SG nuclei, is also restored when hsrω transcripts are down-regulated in Act-GAL4 driven Msl-1-RNAi or Msl-2-RNAi genetic background. NURF301, a known chromatin remodeler, when down-regulated shows decondensed X chromosome in male larvae. Down-regulation of hsrω results in restoration of chromosome architecture without affecting the level of ISWI protein-another chromatin remodeler protein, known to interacting with hsrω.

scholarly journals Targeting of the dosage-compensated male X-chromosome during early Drosophila development

2019 ◽  
Author(s):  
LE Rieder ◽  
WT Jordan ◽  
EN Larschan
Keyword(s):  
Early Development ◽  
X Chromosome ◽  
Dosage Compensation ◽  
Binding Sites ◽  
Zinc Finger Protein ◽  
Multi Stage ◽  
Compensation Factor ◽  
Zygotic Transcription ◽  
Male Specific ◽  
Lethal Dosage

ABSTRACTThe essential process of dosage compensation, which corrects for the imbalance in X-linked gene expression between XX females and XY males, represents a key model for how genes are targeted for coordinated regulation. However, the mechanism by which dosage compensation complexes identify the X-chromosome during early development remained unknown because of the difficulty of sexing embryos prior to zygotic transcription. We used meiotic drive to sex Drosophila embryos prior to zygotic transcription and ChIP-seq to measure dynamics of dosage compensation factor targeting. The Drosophila Male-Specific Lethal dosage compensation complex (MSLc) requires the ubiquitous zinc-finger protein Chromatin-Linked Adaptor for MSL Proteins (CLAMP) to identify the X-chromosome. We observe a multi-stage process in which MSLc first identifies CLAMP binding sites throughout the genome followed by concentration at the strongest X-linked MSLc sites. We provide insight into the dynamic mechanism by which a large transcription complex identifies its binding sites during early development.

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