Project description:Haploinsufficiency and aneuploidy are two phenomena, where alteration of gene dosage causes severe cellular defects ultimately resulting in developmental failures and disease. One remarkable exception is the X chromosome, where copy number differences between males and females are buffered through the action of dosage compensation systems. In Drosophila, the Male-Specific Lethal complex (MSLc) mediates two-fold upregulation of the single male X chromosome via Histone H4 lysine 16 acetylation (H4K16ac). The evolutionary origin and conservation of this process orchestrated by MSL2, the only male-specific protein within the fly MSLc, have remained unclear. Here, we report that MSL2, in addition to its function on the X, targets dosage-sensitive autosomal genes involved in patterning and morphogenesis. We show that the precise regulation of these genes by MSL2 is required for proper development of the fly wing. This set of dosage sensitive genes maintained such regulation during evolution, as MSL2 binds and similarly regulates mouse orthologues via deposition of H4K16ac. We propose that MSL2-mediated H4K16ac is an evolutionarily conserved process mediating gene-by-gene dosage compensation across flies and mammals.
Project description:Haploinsufficiency and aneuploidy are two phenomena, where alteration of gene dosage causes severe cellular defects ultimately resulting in developmental failures and disease. One remarkable exception is the X chromosome, where copy number differences between males and females are buffered through the action of dosage compensation systems. In Drosophila, the Male-Specific Lethal complex (MSLc) mediates two-fold upregulation of the single male X chromosome via Histone H4 lysine 16 acetylation (H4K16ac). The evolutionary origin and conservation of this process orchestrated by MSL2, the only male-specific protein within the fly MSLc, have remained unclear. Here, we report that MSL2, in addition to its function on the X, targets dosage-sensitive autosomal genes involved in patterning and morphogenesis. We show that the precise regulation of these genes by MSL2 is required for proper development of the fly wing. This set of dosage sensitive genes maintained such regulation during evolution, as MSL2 binds and similarly regulates mouse orthologues via deposition of H4K16ac. We propose that MSL2-mediated H4K16ac is an evolutionarily conserved process mediating gene-by-gene dosage compensation across flies and mammals.
Project description:Haploinsufficiency and aneuploidy are two phenomena, where alteration of gene dosage causes severe cellular defects ultimately resulting in developmental failures and disease. One remarkable exception is the X chromosome, where copy number differences between males and females are buffered through the action of dosage compensation systems. In Drosophila, the Male-Specific Lethal complex (MSLc) mediates two-fold upregulation of the single male X chromosome via Histone H4 lysine 16 acetylation (H4K16ac). The evolutionary origin and conservation of this process orchestrated by MSL2, the only male-specific protein within the fly MSLc, have remained unclear. Here, we report that MSL2, in addition to its function on the X, targets dosage-sensitive autosomal genes involved in patterning and morphogenesis. We show that the precise regulation of these genes by MSL2 is required for proper development of the fly wing. This set of dosage sensitive genes maintained such regulation during evolution, as MSL2 binds and similarly regulates mouse orthologues via deposition of H4K16ac. We propose that MSL2-mediated H4K16ac is an evolutionarily conserved process mediating gene-by-gene dosage compensation across flies and mammals.
Project description:Haploinsufficiency and aneuploidy are two phenomena, where alteration of gene dosage causes severe cellular defects ultimately resulting in developmental failures and disease. One remarkable exception is the X chromosome, where copy number differences between males and females are buffered through the action of dosage compensation systems. In Drosophila, the Male-Specific Lethal complex (MSLc) mediates two-fold upregulation of the single male X chromosome via Histone H4 lysine 16 acetylation (H4K16ac). The evolutionary origin and conservation of this process orchestrated by MSL2, the only male-specific protein within the fly MSLc, have remained unclear. Here, we report that MSL2, in addition to its function on the X, targets dosage-sensitive autosomal genes involved in patterning and morphogenesis. We show that the precise regulation of these genes by MSL2 is required for proper development of the fly wing. This set of dosage sensitive genes maintained such regulation during evolution, as MSL2 binds and similarly regulates mouse orthologues via deposition of H4K16ac. We propose that MSL2-mediated H4K16ac is an evolutionarily conserved process mediating gene-by-gene dosage compensation across flies and mammals.
Project description:Drosophila males double transcription of their single X chromosome to equalize X-linked gene expression with females, which carry two X chromosomes. Increased transcription requires the Male-Specific Lethal (MSL) complex. The MSL2 protein is essential component of the MSL complex. MSL2 is the only protein that is strictly limited to males. MSL2 together with MSL1 forms the core of the MSL complex. The global effect of msl2 mutation on gene expression was measured by microarray analysis. We found that expression of the X chromosome was decreased in msl21 male larvae, supporting the involvement of MSL2 in the up-regulation of X-linked genes. However, there was no change in expression of 4th chromosomal and heterochromatic genes. This finding is broadly comparable to reports of reduced X chromosome expression following msl2 RNAi knockdown in S2 cells. Hence MSL2 is required for up-regulation of male X chromosome where as it is not necessary for normal expression of 4th chromosomal genes and heterochromatic genes in Drosophila melanogaster males.
Project description:The Drosophila male-specific lethal (MSL) complex binds to the male X chromosome to activate transcription, and consists of five proteins, MSL1, MSL2, MSL3, MOF, MLE, and two roX RNAs. The MLE helicase remodels the roX lncRNAs, enabling the lncRNA-mediated assembly of the Drosophila dosage compensation complex. MSL2 is expressed only in males and interacts with the N-terminal zinc-finger of the transcription factor CLAMP that is important for specific recruitment of the MSL complex on the male X chromosome. Here we found that the unstructured C-terminal region of MLE interacts with 6-7 zinc-finger domains of CLAMP. In vitro 4-5 zinc fingers are critical for specific DNA-binding of CLAMP with GA-repeats, which constitute the core motif at the high affinity binding sites for MSL proteins. Deletion of the Clamp Binding Domain (CBD) in MLE results in decreasing of MSL proteins association with male X chromosome and increasing of male lethality. These results suggest that interactions of unstructured regions in MSL2 and MLE with CLAMP zinc finger domains are important for the specific recruitment of the MSL complex on the male X chromosome.
Project description:Drosophila males double transcription of their single X chromosome to equalize X-linked gene expression with females, which carry two X chromosomes. Increased transcription requires the Male-Specific Lethal (MSL) complex. The MSL2 protein is essential component of the MSL complex. MSL2 is the only protein that is strictly limited to males. MSL2 together with MSL1 forms the core of the MSL complex. The global effect of msl2 mutation on gene expression was measured by microarray analysis. We found that expression of the X chromosome was decreased in msl21 male larvae, supporting the involvement of MSL2 in the up-regulation of X-linked genes. However, there was no change in expression of 4th chromosomal and heterochromatic genes. This finding is broadly comparable to reports of reduced X chromosome expression following msl2 RNAi knockdown in S2 cells. Hence MSL2 is required for up-regulation of male X chromosome where as it is not necessary for normal expression of 4th chromosomal genes and heterochromatic genes in Drosophila melanogaster males. Experiment Overall Design: Total RNA was prepared from groups of 50 (or more in case of smaller larvae) third instar larvae by TRIzol (Invitrogen) extraction and purified using the RNeasy kit (Qiagen). Three independent RNA preparations for each genotype served as templates for probe synthesis. Affymetrix Drosophila Genome 2.0 chips were hybridized to these probes (Santa Clara, CA). Affymetrix Gene expression data was background corrected, normalized and summarized into a one expression value per sample and probeset using the RMA (robust multi-array average) algorithm. Changes in gene expression (log2 fold changes) were determined by comparing the mean RMA expression values in the msl21 sample to the mean RMA expression values in the msl21/+ samples.
Project description:Drosophila males double transcription of their single X chromosome to equalize X-linked gene expression with females, which carry two X chromosomes. Increased transcription requires the Male-Specific Lethal (MSL) complex. One of the primary functions of the MSL complex is thought to be enrichment of H4Ac16 on the male X chromosome, a modification linked to elevated transcription. The roX1 and roX2 RNAs are essential but redundant components of the MSL complex. Simultaneous removal of both roX RNAs reduces MSL X-localization and leads to ectopic binding of these proteins at autosomal sites and to the chromocenter. Some H4Ac16 accumulates at these ectopic sites in roX1- roX2- males, suggesting the possibility of increased expression. The global effect of roX mutations on gene expression was measured by microarray analysis. We found that expression of the X chromosome was decreased by 26% in roX1- roX2- male larvae, supporting the involvement of roX RNAs in the up-regulation of X-linked genes. This finding is broadly comparable to reports of reduced X chromosome expression following msl2 RNAi knockdown in S2 cells. In spite of strong MSL binding and H4Ac16 accumulation at autosomal sites in roX1- roX2- males, enhanced gene expression could not be detected at these sites by microarray analysis or reverse northern blotting. Thus, failure to compensate X-linked genes, rather than inappropriate up-regulation of autosomal genes at ectopic sites of MSL binding, appears to cause male lethality upon loss of roX RNAs. Experiment Overall Design: Total RNA was prepared from groups of 50 third instar larvae by TRIzol (Invitrogen) extraction and purified using the RNeasy kit (Qiagen). Three independent RNA preparations for each genotype served as templates for probe synthesis. Affymetrix Drosophila Genome 2.0 chips were hybridized to these probes (Santa Clara, CA). The affymertrix Drosophila annotation of December 2004 was used to map genes to their cytological locations. Genes were filtered for present/absent calls by a PM-MM (Perfect match- Mismatch) comparison. Autosomal transcripts were normalized on a chip-by-chip basis to bring their median values to 100. The identical degree of adjustment was used to normalize X-linked transcripts. Changes in gene expression were determined by comparing the mean signal intensities of genes on arrays hybridized with roX1SMC17A roX2- probes to those hybridized with roX1+ roX2- probes.
Project description:Drosophila males double transcription of their single X chromosome to equalize X-linked gene expression with females, which carry two X chromosomes. Increased transcription requires the Male-Specific Lethal (MSL) complex. One of the primary functions of the MSL complex is thought to be enrichment of H4Ac16 on the male X chromosome, a modification linked to elevated transcription. The roX1 and roX2 RNAs are essential but redundant components of the MSL complex. Simultaneous removal of both roX RNAs reduces MSL X-localization and leads to ectopic binding of these proteins at autosomal sites and to the chromocenter. Some H4Ac16 accumulates at these ectopic sites in roX1- roX2- males, suggesting the possibility of increased expression. The global effect of roX mutations on gene expression was measured by microarray analysis. We found that expression of the X chromosome was decreased by 26% in roX1- roX2- male larvae, supporting the involvement of roX RNAs in the up-regulation of X-linked genes. This finding is broadly comparable to reports of reduced X chromosome expression following msl2 RNAi knockdown in S2 cells. In spite of strong MSL binding and H4Ac16 accumulation at autosomal sites in roX1- roX2- males, enhanced gene expression could not be detected at these sites by microarray analysis or reverse northern blotting. Thus, failure to compensate X-linked genes, rather than inappropriate up-regulation of autosomal genes at ectopic sites of MSL binding, appears to cause male lethality upon loss of roX RNAs. Keywords: effect of roX1-roX2- mutant on gene expression
Project description:The male-specific lethal dosage compensation complex (MSL complex or DCC), which consists of five proteins and two non-coding roX RNAs, is necessary for the transcriptional enhancement of X-linked genes to compensate for the sex chromosome monosomy in Drosophila XY males, compared with XX females. MSL2 is a single protein component of the DCC that is expressed only in males and is essential for the specific recruitment of the DCC to the high-affinity “entry” sites (HASs) on the X chromosome. MSL2, together with MSL1, forms the heterotetrameric DCC core. Here, we demonstrated that the N-terminal unstructured region of MSL1 interacts with many different DNA-binding proteins that contain clusters of the C2H2 zinc-finger domains. Amino acid deletions in the N-terminal region of MSL1 strongly affect the binding of the DCC to the HASs on the male X chromosome. However, the binding of MSL2 to autosomal promoters was unaffected by amino acid deletions in MSL1. Males expressing mutant variants of MSL1 died during the larvae stage, demonstrating the critical role played by the N-terminal region in DCC activity. Our results suggest that MSL1 interacts with a variety of DNA-binding proteins to increase the specificity of DCC recruitment to the male X chromosome.