Activation Of Specific Genes Research Articles

Expression of Estrogen Receptor Alpha (ESR1) in Breast Cancer: Role in Critical Diagnosis

Estrogen receptors (ERs) are a group of receptor proteins that are activated by the hormone estrogen. Once activated by estrogen, the ER can translocate into the nucleus and bind with DNA to regulate the activity of different genes. About 80% of all breast cancers are "ER-positive" which is one of the two types of hormonereceptor- positive breast cancer. Tumors that are ERpositive are much more likely to respond to hormone therapy than tumors that are ER/PR (estrogen/progesterone) negative. The presence of ER in breast tumors indicates an increased likelihood of response to anti-estrogen therapy. In the present study, we have developed and characterized a monoclonal antibody against Estrogen receptors. The level of expression of ER is examined in human breast cancer tissues by using the developed anti-ER monoclonal antibody in immunohistochemistry. It was found that this monoclonal antibody is specific to estrogen receptors and shows minimal cross-reaction with other members of the family which were validated by ELISA, Western blotting and Immuno-histochemistry. It strongly strains nuclei of epithelial cells in breast carcinomas and so the developed monoclonal antibody can be used in the diagnosis of positive breast cancer.

Differential activity of genes with fragments of IS630/TC1/MARINER transposons in the genome of MNEMIOPSIS LEIDYI

<h3>ЦЕЛЬ ИССЛЕДОВАНИЯ</h3> Мобильные генетические элементы (МГЭ) оказывают значительное влияние на структуру и функционирование генома и являются источником новых генов. В результате «молекулярного одомашнивания» гены МГЭ становятся функциональной частью генома хозяина. Суперсемейство ДНК-транспозонов <i>IS630/Tc1/mariner</i> (<i>ITm</i>) является одним из самых широко распространенных и разнообразных. К настоящему времени известно несколько генов, которые появились вследствие кооптации <i>ITm</i>-транспозонов. Данная работа была направлена на поиск генов гребневика <i>Mnemiopsis leidyi</i>, в последовательность которых были включены фрагменты <i>ITm</i>-транспозонов, с последующим анализом их уровня экспрессии. <h3>МАТЕРИАЛ И МЕТОДЫ</h3> В представленной работе для поиска гипотетических химерных генов был использован метод локального выравнивания (BLASTn). Анализ дифференциальной активности генов оценивали с помощью совместного использования программ Kallisto и Sleuth. <h3>РЕЗУЛЬТАТЫ И ОБСУЖДЕНИЕ</h3> Не было обнаружено ни одной кДНК, которая бы соответствовала полной кодирующей последовательности транспозазы какого-либо <i>ITm</i>-транспозона <i>M. leidyi</i>. Однако был обнаружен 21 уникальный транскрипт гипотетических химерных генов, имеющих участки гомологичные <i>ITm</i>-транспозонам. Транскрипционный анализ показал, что в процессе раннего эмбрионального развития, а также в тканях гребней и эпителия взрослых животных преобладающая доля гипотетических химерных генов не экспрессируется либо экспрессируется на низком уровне. Однако в нескольких локусах фиксируется дифференциальный уровень активности в процессе регенерации. <h3>ЗАКЛЮЧЕНИЕ</h3> Дифференциальная активность отдельных гипотетических химерных генов в процессе регенерации может свидетельствовать об их возможном «одомашнивании» и вовлеченности в молекулярно-генетические процессы гребневиков.

Screening for Biomarkers of Actinobacteria Associated with Water-Damaged Buildings – Part 1

Recent publications 1,2 have presented the view that a wider variety of microbial contaminants are responsible for adverse human health effects in susceptible individuals exposed to the microbial “soup” that results in water-damaged buildings (WDB) than previously ascribed. Those articles presented an in-depth understanding of the expanded use of Next Generation Sequencing (NGS) to detect the bacterial taxa present in these affected environments. When correlated with data from transcriptomic assays, these studies defined specific causation of innate immune activation by a growing list of microbial colonizers. Specifically, it was reported that a correlation existed between certain Actinobacteria as shown by NGS, with differential gene activation, from a transcriptomic assay (GENIE) detecting a defined clinical response. This review seeks to assess the published literature to find and determine the potential for candidates that could be relied upon to act as a biomarker for Actinobacteria in dust and other samples in order to indicate the likelihood of Actinobacteria dominance or prevalence, sufficient to warrant progression to confirmation by NGS, much like endotoxins are broadly accepted as a biomarker for colonization by broad spectra of Gram-negative bacilli in WDB.

Parathyroid hormone-related protein (PTHrP)-dependent modulation of gene expression signatures in cancer cells.

PTHrP is encoded by PTHLH gene which can generate by alternative promoter usage and splicing mechanisms at least three mature peptides of 139, 141 and 173 amino acids with distinct carboxy terminus. PTHrP may undergo proteolytic processing into smaller bioactive forms, comprising an amino terminus peptide, which is the mediator of the "classical" PTH-like effect, as well as midregion and carboxy terminus peptides that act as multifaceted critical regulator of proliferation, differentiation and apoptosis via the reprogramming of gene expression in normal and neoplastic cells. Moreover, a nuclear/nucleolar localization signal sequence is present in the [87-107] domain allowing PTHrP nuclear import and "intracrine" effect additional to the autocrine/paracrine one. Within the large number of data available in the literature on PTHrP bioactivities, the goal of this chapter is to pick up selected studies that report the detection of molecular signatures of cancer cell exposure to PTHrP, either as full-length protein or discrete peptides, demonstrated by individual gene or whole genome expression profiling, briefly recapitulating the biological implications associated with the specific gene activation or silencing.

MDrop-Seq: Massively Parallel Single-Cell RNA-Seq of Saccharomyces cerevisiae and Candida albicans.

Advances in high-throughput single-cell RNA sequencing (scRNA-seq) have been limited by technical challenges such as tough cell walls and low RNA quantity that prevent transcriptomic profiling of microbial species at throughput. We present microbial Drop-seq or mDrop-seq, a high-throughput scRNA-seq technique that is demonstrated on two yeast species, Saccharomyces cerevisiae, a popular model organism, and Candida albicans, a common opportunistic pathogen. We benchmarked mDrop-seq for sensitivity and specificity and used it to profile 35,109 S. cerevisiae cells to detect variation in mRNA levels between them. As a proof of concept, we quantified expression differences in heat shock S. cerevisiae using mDrop-seq. We detected differential activation of stress response genes within a seemingly homogenous population of S. cerevisiae under heat shock. We also applied mDrop-seq to C. albicans cells, a polymorphic and clinically relevant species of yeast with a thicker cell wall compared to S. cerevisiae. Single-cell transcriptomes in 39,705 C. albicans cells were characterized using mDrop-seq under different conditions, including exposure to fluconazole, a common anti-fungal drug. We noted differential regulation in stress response and drug target pathways between C. albicans cells, changes in cell cycle patterns and marked increases in histone activity when treated with fluconazole. We demonstrate mDrop-seq to be an affordable and scalable technique that can quantify the variability in gene expression in different yeast species. We hope that mDrop-seq will lead to a better understanding of genetic variation in pathogens in response to stimuli and find immediate applications in investigating drug resistance, infection outcome and developing new drugs and treatment strategies.

DNA damage in brain may lead to cognitive dysfunctions and reduced longevity in WNIN/Ob obese rats

AbstractBackgroundOne of the most common neurodegenerative diseases is Alzheimer’s disease where complex etiological alterations have been observed along with the typical pathology. Specifically, it has been proposed that epigenetic activation of specific genes due to other physiological conditions may also contribute to its pathology.MethodAgeing being one of the strongest risk factor where accumulation of DNA damage is rampant, we evaluated the extent in the brain of 15 months old WNIN/Ob obese rats. Early accumulation of DNA damage in brain can result in devastating genetic instability and wide array of physiological problems. WNIN obese rats have significantly reduced longevity (average lifespan of 15‐18 months). The extent of DNA damage in brain was studied as a hallmark of senescence in order to establish this rat as a model of aging related studies. DNA damage was assessed at the single cell level in neocortex and hippocampus of WNIN obese rats, WNIN lean littermates and normal WNIN controls at 3 and 15 months of age by Comet Assay. The samples were processed for neutral and alkaline electrophoresis, followed by fluorescent staining and analysis.ResultThe extent of DNA damage in the form of single‐strand breaks (SSBs) as well as double‐strand breaks (DSBs) in cells of neocortex and hippocampus of young WNIN obese rats was comparable with those seen in the 15 months old normal WNIN rats. Interestingly the extent of SSBs and DSBs in young WNIN lean littermates and WNIN controls were comparable.ConclusionOnset of significant DNA damage in different brain regions of obese rats at a much younger age is a plausible cause of reduced longevity observed in this novel obese rat model.

Occurrence of albinism during wheat androgenesis is correlated with repression of the key genes required for proper chloroplast biogenesis.

The phenomenon of albinism in wheat androgenesis is linked to the transcriptional repression of specific genes involved in chloroplast biogenesis during the first weeks of in vitro culture. Isolated microspore culture is widely used to accelerate breeding programs and produce new cultivars. However, in cereals and particularly in wheat, the use of this technique is limited due to the high proportion of regenerated albino plantlets. The causes and mechanisms leading to the formation of albino plantlets in wheat remain largely unknown and, to date, no concrete solution has been found to make it possible to overcome this barrier. We performed a molecular study of proplastid-to-chloroplast differentiation within wheat microspore cultures by analyzing the expression of 20 genes specifically involved in chloroplast biogenesis. Their expression levels were compared between two wheat genotypes that exhibit differential capacities to regenerate green plantlets, i.e., Pavon and Paledor, which produce high and low rates of green plants, respectively. We observed that chloroplast biogenesis within wheat microspores was affected as of the very early stages of the androgenesis process. A successful transition from a NEP- to a PEP-dependent transcription during early plastid development was found to be strongly correlated with the formation of green plantlets, while failure of this transition was strongly correlated with the regeneration of albino plantlets. The very low expression of plastid-encoded 16S and 23S rRNAs within plastids of the recalcitrant genotype Paledor suggests a low translation activity in albino plastids. Furthermore, a delay in the activation of the transcription of nuclear encoded key genes like GLK1 related to chloroplast biogenesis was observed in multicellular structures and pro-embryos of the genotype Paledor. These data help to understand the phenomenon of albinism in wheat androgenesis, which appears to be linked to the transcriptional activation of specific genes involved in the initial steps of chloroplast biogenesis that occurs between days 7 and 21 of in vitro culture.

Development of Synthetic DNA Circuit and Networks for Molecular Information Processing.

Deoxyribonucleic acid (DNA), a genetic material, encodes all living information and living characteristics, e.g., in cell, DNA signaling circuits control the transcription activities of specific genes. In recent years, various DNA circuits have been developed to implement a wide range of signaling and for regulating gene network functions. In particular, a synthetic DNA circuit, with a programmable design and easy construction, has become a crucial method through which to simulate and regulate DNA signaling networks. Importantly, the construction of a hierarchical DNA circuit provides a useful tool for regulating gene networks and for processing molecular information. Moreover, via their robust and modular properties, DNA circuits can amplify weak signals and establish programmable cascade systems, which are particularly suitable for the applications of biosensing and detecting. Furthermore, a biological enzyme can also be used to provide diverse circuit regulation elements. Currently, studies regarding the mechanisms and applications of synthetic DNA circuit are important for the establishment of more advanced artificial gene regulation systems and intelligent molecular sensing tools. We therefore summarize recent relevant research progress, contributing to the development of nanotechnology-based synthetic DNA circuits. By summarizing the current highlights and the development of synthetic DNA circuits, this paper provides additional insights for future DNA circuit development and provides a foundation for the construction of more advanced DNA circuits.

The Nucleoskeleton: Crossroad of Mechanotransduction in Skeletal Muscle.

Intermediate filaments (IFs) are a primary structural component of the cytoskeleton extending throughout the muscle cell (myofiber). Mechanotransduction, the process by which mechanical force is translated into a biochemical signal to activate downstream cellular responses, is crucial to myofiber function. Mechanical forces also act on the nuclear cytoskeleton, which is integrated with the myofiber cytoskeleton by the linker of the nucleoskeleton and cytoskeleton (LINC) complexes. Thus, the nucleus serves as the endpoint for the transmission of force through the cell. The nuclear lamina, a dense meshwork of lamin IFs between the nuclear envelope and underlying chromatin, plays a crucial role in responding to mechanical input; myofibers constantly respond to mechanical perturbation via signaling pathways by activation of specific genes. The nucleus is the largest organelle in cells and a master regulator of cell homeostasis, thus an understanding of how it responds to its mechanical environment is of great interest. The importance of the cell nucleus is magnified in skeletal muscle cells due to their syncytial nature and the extreme mechanical environment that muscle contraction creates. In this review, we summarize the bidirectional link between the organization of the nucleoskeleton and the contractile features of skeletal muscle as they relate to muscle function.

NRF1 association with AUTS2-Polycomb mediates specific gene activation in the brain

The heterogeneous family of complexes comprising Polycomb repressive complex 1 (PRC1) is instrumental for establishing facultative heterochromatin that is repressive to transcription. However, two PRC1 species, ncPRC1.3 and ncPRC1.5, are known to comprise novel components, AUTS2, P300, and CK2, that convert this repressive function to that of transcription activation. Here, we report that individuals harboring mutations in the HX repeat domain of AUTS2 exhibit defects in AUTS2 and P300 interaction as well as a developmental disorder reflective of Rubinstein-Taybi syndrome, which is mainly associated with a heterozygous pathogenic variant in CREBBP/EP300. Moreover, the absence of AUTS2 or mutation in its HX repeat domain gives rise to misregulation of a subset of developmental genes and curtails motor neuron differentiation of mouse embryonic stem cells. The transcription factor nuclear respiratory factor 1 (NRF1) has a novel and integral role in this neurodevelopmental process, being required for ncPRC1.3 recruitment to chromatin.

Identification of hub genes and molecular subtypes in COVID-19 based on WGCNA.

The heterogeneity of clinical manifestations and mortality rates in Coronavirus disease 2019 (COVID-19) patients may be related to the existence of molecular subtypes in COVID-19. To improve current management, it is essential to find the hub genes and pathways associated with different COVID-19 subtypes. The whole-genome sequencing information (GSE156063, GSE163151) of nasopharyngeal swabs from normal subjects and COVID-19 patients were downloaded from the Gene Expression Omnibus (GEO) database. The molecular subtypes of patients with COVID-19 were classified using the "consistent clustering" method, and the specific genes associated with each subtype were found. Differentially expressed genes (DEGs) were screened between normal subjects and COVID-19 patients; the Weighted gene co-expression network analysis (WGCNA) method was used to find the key module genes of COVID-19 patients. Subtype-specific, differentially expressed and module-related genes were collected and intersected. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were carried out and protein-protein interaction (PPI) networks were generated. The pathways enriched in COVID-19 subtypes were analyzed by gene set variation analysis (GSVA). Patients with COVID-19 were divided into three subtypes, and there was no significant difference in gender and age distribution between subtypes. 82 differential gene pathways were screened between Subtypes I and II, 131 differential gene pathways were screened between Subtypes I and III, and 107 differential gene pathways were screened between Subtypes II and III. Finally, 44 differentially expressed key genes were screened, including 11 hub genes (RSAD2, IFIT1, MX1, OAS1, OAS2, BST2, IFI27, IFI35, IFI6, IFITM3, STAT2). There are significant differences in gene activation and pathway enrichment among different molecular subtypes of COVID-19, which may account for the heterogeneity in clinical presentation and the prognosis of patients.

Abstract MP259: The Role Of Sertad4 In Pathological Cardiac Remodeling

Over 6 million Americans suffer from heart failure (HF) while the 5-year mortality rate following first admission for HF is over 40%. Cardiac fibrosis is a clinical hallmark of HF, regardless of the initiating pathology and is thought to contribute to disease progression. Using an epigenomics discovery approach, we uncovered a nuclear protein, Sertad4, as a potential anti-fibrotic target. Our data indicate that Sertad4 is a positive regulator of fibroblast activation. Specifically, cultured cardiac fibroblast experiments demonstrate that Sertad4 targeting with shRNAs blocks fibroblast proliferation and causes cells to arrest in the G2/M phase of the cell cycle. Also, shRNA targeting of Sertad4 dramatically blocked activation of myofibroblast differentiation genes (αSMA/POSTN/COL1A1). Mechanistically, these effects appear to be mediated by Sertad4 regulation of SMAD2 protein stability in the presence of TGF-β1 stimulation as demonstrated by proteasome inhibition experiments. RNA-seq analysis indicate that Sertad4 also regulates the expression of genes involved in ubiquitination and proteasome degradation. Next, we sought to determine the effect of global Sertad4 knockout on post-myocardial infarct (MI) remodeling and cardiac function in mice. After 4 weeks of permanent LAD ligation, echocardiography was performed to measure systolic function. Relative to wild-type (WT) controls, the Sertad4 KO mice showed preserved systolic function as evident by improved ejection fraction (WT 14.4 +/- 3.6 vs. KO 33.9+/-5.9, p=0.035) and fractional shortening (WT 6.5 +/- 1.7 vs. KO 16.4 +/- 3.4, p=0.046). β-gal staining in the Sertad4/LacZ reporter mouse subjected to MI showed robust Sertad4/LacZ expression in the ischemic scar and boarder-zone with almost no expression in control hearts. This data supports the notion that Sertad4 has a key role in cardiac remodeling in response to ischemic injury.

TYK2 in Cancer Metastases: Genomic and Proteomic Discovery.

Simple SummaryCancer deaths are predominantly due to metastases rather than the primary tumors, and thus there is an urgent need for the discovery of more effective drug therapies for metastatic cancer. Recent genomics, transcriptomics, and proteomics studies have identified tyrosine kinase 2 (TYK2) as an oncogene that is frequently mutated or overexpressed in many types of cancer and metastases. A member of the Janus kinase (JAK) family, TYK2 mediates the signals of numerous cytokines involved in immune and inflammatory signaling. In cancer cells, activation of TYK2 can lead to decreased cell death as well as increased cell growth and invasion. Multiple drugs that specifically block TYK2 or JAKs are currently FDA-approved or in clinical trials. In this review, we provide an overview of the screening, molecular, and animal studies that have characterized the role of TYK2 in cancer and metastases, and the potential of TYK2 inhibitors as effective cancer therapies. Advances in genomic analysis and proteomic tools have rapidly expanded identification of biomarkers and molecular targets important to cancer development and metastasis. On an individual basis, personalized medicine approaches allow better characterization of tumors and patient prognosis, leading to more targeted treatments by detection of specific gene mutations, overexpression, or activity. Genomic and proteomic screens by our lab and others have revealed tyrosine kinase 2 (TYK2) as an oncogene promoting progression and metastases of many types of carcinomas, sarcomas, and hematologic cancers. TYK2 is a Janus kinase (JAK) that acts as an intermediary between cytokine receptors and STAT transcription factors. TYK2 signals to stimulate proliferation and metastasis while inhibiting apoptosis of cancer cells. This review focuses on the growing evidence from genomic and proteomic screens, as well as molecular studies that link TYK2 to cancer prevalence, prognosis, and metastasis. In addition, pharmacological inhibition of TYK2 is currently used clinically for autoimmune diseases, and now provides promising treatment modalities as effective therapeutic agents against multiple types of cancer.

The promise of precision medicine in autism

Autism spectrum disorder (ASD) is a clinically and etiologically diverse developmental condition characterized by diminished social interactions, impaired communication, and repetitive and/or restrictive behaviors. Recent advances in ASD genetics pave the way for implementation of precision medicine in clinical management of autism.

Single-nuclear transcriptomics reveals diversity of proximal tubule cell states in a dynamic response to acute kidney injury

Acute kidney injury (AKI), commonly caused by ischemia, sepsis, or nephrotoxic insult, is associated with increased mortality and a heightened risk of chronic kidney disease (CKD). AKI results in the dysfunction or death of proximal tubule cells (PTCs), triggering a poorly understood autologous cellular repair program. Defective repair associates with a long-term transition to CKD. We performed a mild-to-moderate ischemia-reperfusion injury (IRI) to model injury responses reflective of kidney injury in a variety of clinical settings, including kidney transplant surgery. Single-nucleus RNA sequencing of genetically labeled injured PTCs at 7-d ("early") and 28-d ("late") time points post-IRI identified specific gene and pathway activity in the injury-repair transition. In particular, we identified Vcam1+/Ccl2+ PTCs at a late injury stage distinguished by marked activation of NF-κB-, TNF-, and AP-1-signaling pathways. This population of PTCs showed features of a senescence-associated secretory phenotype but did not exhibit G2/M cell cycle arrest, distinct from other reports of maladaptive PTCs following kidney injury. Fate-mapping experiments identified spatially and temporally distinct origins for these cells. At the cortico-medullary boundary (CMB), where injury initiates, the majority of Vcam1+/Ccl2+ PTCs arose from early replicating PTCs. In contrast, in cortical regions, only a subset of Vcam1+/Ccl2+ PTCs could be traced to early repairing cells, suggesting late-arising sites of secondary PTC injury. Together, these data indicate even moderate IRI is associated with a lasting injury, which spreads from the CMB to cortical regions. Remaining failed-repair PTCs are likely triggers for chronic disease progression.

The Pleiotropic Intricacies of Hedgehog Signaling: From Craniofacial Patterning to Carcinogenesis.

Hedgehog signaling was discovered more than 40 years ago in experiments demonstrating that it is a fundamental mediator of limb development. Since that time, it has been shown to be important in development, homeostasis, and disease. The hedgehog pathway proceeds through a pathway highly conserved throughout animals beginning with the extracellular diffusion of hedgehog ligands, proceeding through an intracellular signaling cascade, and ending with the activation of specific target genes. A vast amount of research has been done elucidating hedgehog signaling mechanisms and regulation. This research has found a complex system of genetics and signaling that helps determine how organisms develop and function. This review provides an overview of what is known about hedgehog genetics and signaling, followed by an in-depth discussion of the role of hedgehog signaling in craniofacial development and carcinogenesis.

Functional characterization and expression profile of microsomal FAD2 and FAD3 genes involved in linoleic and α-linolenic acid production in Leucas cephalotes.

The online version contains supplementary material available at 10.1007/s12298-021-01016-z.

Computational Modeling of Gene-Specific Transcriptional Repression, Activation and Chromatin Interactions in Leukemogenesis by LASSO-Regularized Logistic Regression.

Many physiological and pathological pathways are dependent on gene-specific on/off regulation of transcription. Some genes are repressed, while others are activated. Although many previous studies have analyzed the mechanisms of gene-specific repression and activation, these studies are mainly based on the use of candidate genes, which are either repressed or activated, without simultaneously comparing and contrasting both groups of genes. There is also insufficient consideration of gene locations. Here we describe an integrated machine learning approach, using LASSO-regularized logistic regression, to model gene-specific repression and activation and the underlying contribution of chromatin interactions. LASSO-regularized logistic regression accurately predicted gene-specific transcriptional events and robustly detected the rate-limiting factors that underlie the differences of gene activation and repression. An example was provided by the leukemogenic transcription factor AML1-ETO, which is responsible for 10-15 percent of all acute myeloid leukemia cases. The analysis of AML1-ETO has also revealed novel networks of chromatin interactions and uncovered an unexpected role for E-proteins in AML1-ETO-p300 interactions and a role for the pre-existing gene state in governing the transcriptional response. Our results show that logistic regression-based probabilistic modeling is a promising tool to decipher mechanisms that integrate gene regulation and chromatin interactions in regulated transcription.

Integrated requirement of non‐specific and sequence‐specific DNA binding in Myc‐driven transcription

Eukaryotic transcription factors recognize specific DNA sequence motifs, but are also endowed with generic, non-specific DNA-binding activity. How these binding modes are integrated to determine select transcriptional outputs remains unresolved. We addressed this question by site-directed mutagenesis of the Myc transcription factor. Impairment of non-specific DNA backbone contacts caused pervasive loss of genome interactions and gene regulation, associated with increased intra-nuclear mobility of the Myc protein in murine cells. In contrast, a mutant lacking base-specific contacts retained DNA-binding and mobility profiles comparable to those of the wild-type protein, but failed to recognize its consensus binding motif (E-box) and could not activate Myc-target genes. Incidentally, this mutant gained weak affinity for an alternative motif, driving aberrant activation of different genes. Altogether, our data show that non-specific DNA binding is required to engage onto genomic regulatory regions; sequence recognition in turn contributes to transcriptional activation, acting at distinct levels: stabilization and positioning of Myc onto DNA, and-unexpectedly-promotion of its transcriptional activity. Hence, seemingly pervasive genome interaction profiles, as detected by ChIP-seq, actually encompass diverse DNA-binding modalities, driving defined, sequence-dependent transcriptional responses.

Kinome-Wide RNAi Screen Uncovers Role of Ballchen in Maintenance of Gene Activation by Trithorax Group in Drosophila.

Polycomb group (PcG) and trithorax group (trxG) proteins are evolutionary conserved factors that contribute to cell fate determination and maintenance of cellular identities during development of multicellular organisms. The PcG maintains heritable patterns of gene silencing while trxG acts as anti-silencing factors by conserving activation of cell type specific genes. Genetic and molecular analysis has revealed extensive details about how different PcG and trxG complexes antagonize each other to maintain cell fates, however, the cellular signaling components that contribute to the preservation of gene expression by PcG/trxG remain elusive. Here, we report an ex vivo kinome-wide RNAi screen in Drosophila aimed at identifying cell signaling genes that facilitate trxG in counteracting PcG mediated repression. From the list of trxG candidates, Ballchen (BALL), a histone kinase known to phosphorylate histone H2A at threonine 119 (H2AT119p), was characterized as a trxG regulator. The ball mutant exhibits strong genetic interactions with Polycomb (Pc) and trithorax (trx) mutants and loss of BALL affects expression of trxG target genes. BALL co-localizes with Trithorax on chromatin and depletion of BALL results in increased H2AK118 ubiquitination, a histone mark central to PcG mediated gene silencing. Moreover, BALL was found to substantially associate with known TRX binding sites across the genome. Genome wide distribution of BALL also overlaps with H3K4me3 and H3K27ac at actively transcribed genes. We propose that BALL mediated signaling positively contributes to the maintenance of gene activation by trxG in counteracting the repressive effect of PcG.