Genome-wide RNAi screen in Drosophila reveals Enok as a novel trithorax group regulator
Abstract Background Polycomb group (PcG) and trithorax group (trxG) proteins contribute to the specialization of cell types by maintaining differential gene expression patterns. Initially discovered as positive regulators of HOX genes in forward genetic screens, trxG counteracts PcG-mediated repress...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
BMC
2019-09-01
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| Series: | Epigenetics & Chromatin |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s13072-019-0301-x |
| _version_ | 1818976256986710016 |
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| author | Zain Umer Jawad Akhtar Muhammad Haider Farooq Khan Najma Shaheen Muhammad Abdul Haseeb Khalida Mazhar Aziz Mithani Saima Anwar Muhammad Tariq |
| author_facet | Zain Umer Jawad Akhtar Muhammad Haider Farooq Khan Najma Shaheen Muhammad Abdul Haseeb Khalida Mazhar Aziz Mithani Saima Anwar Muhammad Tariq |
| author_sort | Zain Umer |
| collection | DOAJ |
| description | Abstract Background Polycomb group (PcG) and trithorax group (trxG) proteins contribute to the specialization of cell types by maintaining differential gene expression patterns. Initially discovered as positive regulators of HOX genes in forward genetic screens, trxG counteracts PcG-mediated repression of cell type-specific genes. Despite decades of extensive analysis, molecular understanding of trxG action and regulation are still punctuated by many unknowns. This study aimed at discovering novel factors that elicit an anti-silencing effect to facilitate trxG-mediated gene activation. Results We have developed a cell-based reporter system and performed a genome-wide RNAi screen to discover novel factors involved in trxG-mediated gene regulation in Drosophila. We identified more than 200 genes affecting the reporter in a manner similar to trxG genes. From the list of top candidates, we have characterized Enoki mushroom (Enok), a known histone acetyltransferase, as an important regulator of trxG in Drosophila. Mutants of enok strongly suppressed extra sex comb phenotype of Pc mutants and enhanced homeotic transformations associated with trx mutations. Enok colocalizes with both TRX and PC at chromatin. Moreover, depletion of Enok specifically resulted in an increased enrichment of PC and consequently silencing of trxG targets. This downregulation of trxG targets was also accompanied by a decreased occupancy of RNA-Pol-II in the gene body, correlating with an increased stalling at the transcription start sites of these genes. We propose that Enok facilitates trxG-mediated maintenance of gene activation by specifically counteracting PcG-mediated repression. Conclusion Our ex vivo approach led to identification of new trxG candidate genes that warrant further investigation. Presence of chromatin modifiers as well as known members of trxG and their interactors in the genome-wide RNAi screen validated our reverse genetics approach. Genetic and molecular characterization of Enok revealed a hitherto unknown interplay between Enok and PcG/trxG system. We conclude that histone acetylation by Enok positively impacts the maintenance of trxG-regulated gene activation by inhibiting PRC1-mediated transcriptional repression. |
| first_indexed | 2024-12-20T16:08:58Z |
| format | Article |
| id | doaj.art-e08b229a9b514271b7a9562becd3a419 |
| institution | Directory Open Access Journal |
| issn | 1756-8935 |
| language | English |
| last_indexed | 2024-12-20T16:08:58Z |
| publishDate | 2019-09-01 |
| publisher | BMC |
| record_format | Article |
| series | Epigenetics & Chromatin |
| spelling | doaj.art-e08b229a9b514271b7a9562becd3a4192022-12-21T19:34:04ZengBMCEpigenetics & Chromatin1756-89352019-09-0112111510.1186/s13072-019-0301-xGenome-wide RNAi screen in Drosophila reveals Enok as a novel trithorax group regulatorZain Umer0Jawad Akhtar1Muhammad Haider Farooq Khan2Najma Shaheen3Muhammad Abdul Haseeb4Khalida Mazhar5Aziz Mithani6Saima Anwar7Muhammad Tariq8Syed Babar Ali School of Science and Engineering, Lahore University of Management SciencesSyed Babar Ali School of Science and Engineering, Lahore University of Management SciencesSyed Babar Ali School of Science and Engineering, Lahore University of Management SciencesSyed Babar Ali School of Science and Engineering, Lahore University of Management SciencesSyed Babar Ali School of Science and Engineering, Lahore University of Management SciencesSyed Babar Ali School of Science and Engineering, Lahore University of Management SciencesSyed Babar Ali School of Science and Engineering, Lahore University of Management SciencesSyed Babar Ali School of Science and Engineering, Lahore University of Management SciencesSyed Babar Ali School of Science and Engineering, Lahore University of Management SciencesAbstract Background Polycomb group (PcG) and trithorax group (trxG) proteins contribute to the specialization of cell types by maintaining differential gene expression patterns. Initially discovered as positive regulators of HOX genes in forward genetic screens, trxG counteracts PcG-mediated repression of cell type-specific genes. Despite decades of extensive analysis, molecular understanding of trxG action and regulation are still punctuated by many unknowns. This study aimed at discovering novel factors that elicit an anti-silencing effect to facilitate trxG-mediated gene activation. Results We have developed a cell-based reporter system and performed a genome-wide RNAi screen to discover novel factors involved in trxG-mediated gene regulation in Drosophila. We identified more than 200 genes affecting the reporter in a manner similar to trxG genes. From the list of top candidates, we have characterized Enoki mushroom (Enok), a known histone acetyltransferase, as an important regulator of trxG in Drosophila. Mutants of enok strongly suppressed extra sex comb phenotype of Pc mutants and enhanced homeotic transformations associated with trx mutations. Enok colocalizes with both TRX and PC at chromatin. Moreover, depletion of Enok specifically resulted in an increased enrichment of PC and consequently silencing of trxG targets. This downregulation of trxG targets was also accompanied by a decreased occupancy of RNA-Pol-II in the gene body, correlating with an increased stalling at the transcription start sites of these genes. We propose that Enok facilitates trxG-mediated maintenance of gene activation by specifically counteracting PcG-mediated repression. Conclusion Our ex vivo approach led to identification of new trxG candidate genes that warrant further investigation. Presence of chromatin modifiers as well as known members of trxG and their interactors in the genome-wide RNAi screen validated our reverse genetics approach. Genetic and molecular characterization of Enok revealed a hitherto unknown interplay between Enok and PcG/trxG system. We conclude that histone acetylation by Enok positively impacts the maintenance of trxG-regulated gene activation by inhibiting PRC1-mediated transcriptional repression.http://link.springer.com/article/10.1186/s13072-019-0301-xEpigenetic cellular memoryGene regulationtrithorax groupPolycomb groupEnokGenome-wide RNAi screen |
| spellingShingle | Zain Umer Jawad Akhtar Muhammad Haider Farooq Khan Najma Shaheen Muhammad Abdul Haseeb Khalida Mazhar Aziz Mithani Saima Anwar Muhammad Tariq Genome-wide RNAi screen in Drosophila reveals Enok as a novel trithorax group regulator Epigenetics & Chromatin Epigenetic cellular memory Gene regulation trithorax group Polycomb group Enok Genome-wide RNAi screen |
| title | Genome-wide RNAi screen in Drosophila reveals Enok as a novel trithorax group regulator |
| title_full | Genome-wide RNAi screen in Drosophila reveals Enok as a novel trithorax group regulator |
| title_fullStr | Genome-wide RNAi screen in Drosophila reveals Enok as a novel trithorax group regulator |
| title_full_unstemmed | Genome-wide RNAi screen in Drosophila reveals Enok as a novel trithorax group regulator |
| title_short | Genome-wide RNAi screen in Drosophila reveals Enok as a novel trithorax group regulator |
| title_sort | genome wide rnai screen in drosophila reveals enok as a novel trithorax group regulator |
| topic | Epigenetic cellular memory Gene regulation trithorax group Polycomb group Enok Genome-wide RNAi screen |
| url | http://link.springer.com/article/10.1186/s13072-019-0301-x |
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