scholarly journals Generation and timing of graded responses to morphogen gradients

Development ◽  
2021 ◽  
Vol 148 (24) ◽  
Author(s):  
Shari Carmon ◽  
Felix Jonas ◽  
Naama Barkai ◽  
Eyal D. Schejter ◽  
Ben-Zion Shilo
Keyword(s):  
Gene Expression ◽  
Rna Polymerase Ii ◽  
Target Genes ◽  
Cell Formation ◽  
Embryonic Cell ◽  
Mrna Accumulation ◽  
Temporal Regulation ◽  
Morphogen Gradients ◽  
Graded Response ◽  
Spatio Temporal

ABSTRACT Morphogen gradients are known to subdivide a naive cell field into distinct zones of gene expression. Here, we examine whether morphogens can also induce a graded response within such domains. To this end, we explore the role of the Dorsal protein nuclear gradient along the dorsoventral axis in defining the graded pattern of actomyosin constriction that initiates gastrulation in early Drosophila embryos. Two complementary mechanisms for graded accumulation of mRNAs of crucial zygotic Dorsal target genes were identified. First, activation of target-gene expression expands over time from the ventral-most region of high nuclear Dorsal to lateral regions, where the levels are lower, as a result of a Dorsal-dependent activation probability of transcription sites. Thus, sites that are activated earlier will exhibit more mRNA accumulation. Second, once the sites are activated, the rate of RNA Polymerase II loading is also dependent on Dorsal levels. Morphological restrictions require that translation of the graded mRNA be delayed until completion of embryonic cell formation. Such timing is achieved by large introns, which provide a delay in production of the mature mRNAs. Spatio-temporal regulation of key zygotic genes therefore shapes the pattern of gastrulation.

scholarly journals Generation and timing of graded responses to morphogen gradients

2021 ◽  
Author(s):  
Shari Carmon ◽  
Felix Jonas ◽  
Naama Barkai ◽  
Eyal D Schejter ◽  
Ben-Zion Shilo
Keyword(s):  
Gene Expression ◽  
Target Genes ◽  
Cell Formation ◽  
Embryonic Cell ◽  
Mrna Accumulation ◽  
Morphogen Gradients ◽  
Graded Responses ◽  
Graded Response ◽  
Transcription Sites

Morphogen gradients are known to subdivide a naïve cell field into distinct zones of gene expression. Here we examine whether morphogens can also induce a graded response within such domains. To this end we explore the role of the Dorsal protein nuclear gradient along the dorso-ventral axis in defining the graded pattern of actomyosin constriction that initiates gastrulation in early Drosophila embryos. Two complementary mechanisms for graded accumulation of mRNAs of critical zygotic target genes were identified. First, activation of target-gene expression expands over time from the ventral-most region of high nuclear Dorsal to lateral regions where the levels are lower, due to a Dorsal-dependent priming probability of transcription sites. Thus, sites that are activated earlier will lead to more mRNA accumulation. Second, once the sites are primed, the rate of Pol II loading is also dependent on Dorsal levels. Morphological restrictions require that translation of the graded mRNA be delayed until completion of embryonic cell formation. Such timing is achieved by large introns, that provide a delay in production of the mature mRNAs.

The largest subunit of RNA polymerase II in Dictyostelium: conservation of the unique tail domain and gene expression

1992 ◽  
Vol 70 (9) ◽  
pp. 792-799 ◽  
Author(s):  
Tak Yee Lam ◽  
Lawrence Chan ◽  
Patrick Yip ◽  
Chi-Hung Siu
Keyword(s):  
Gene Expression ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Developmental Process ◽  
Developmental Regulation ◽  
Consensus Sequence ◽  
Protein Band ◽  
Tail Domain ◽  
Mrna Accumulation ◽  
Carboxyl Terminal

cDNAs encoding the largest subunit of RNA polymerase II were isolated from a Dictyostelium cDNA library. A total of 2.9 kilobases (kb) of cDNA was sequenced and the amino acid sequence of the carboxyl-terminal half of the protein was deduced. Similar to other eukaryotic RNA polymerases II, the largest subunit of Dictyostelium RNA polymerase II contains a unique repetitive tail domain at its carboxyl-terminal region. It consists of 24 highly conserved heptapeptide repeats, with a consensus sequence of Tyr-Ser-Pro-Thr-Ser-Pro-Ser. In addition to the tail domain, five segments of the deduced primary structure show > 50% sequence identity with either yeast or mouse protein. RNA blots show that cDNA probes hybridized with a single mRNA species of ~ 6 kb and immunoblots using a monoclonal antibody raised against the tail domain lighted up a single protein band of 200 kilodaltons. Interestingly, expression of the largest subunit of RNA polymerase II appears to be under developmental regulation. The accumulation of its mRNA showed a 60% increase during the first 3 h of development, followed by a steady decrease during the next 6 h. Cells began to accumulate a higher level of the RNA polymerase II mRNA after 9 h of development. When cells were treated with low concentrations of cAMP pulses to stimulate the developmental process, the pattern of mRNA accumulation moved 3 h ahead, but otherwise remained similar to that of control cells.Key words: RNA polymerase, cDNA, sequence homology, gene expression, Dictyostelium.

scholarly journals A PP2A-Integrator complex fine-tunes transcription by opposing CDK9

2020 ◽  
Author(s):  
Stephin J. Vervoort ◽  
Sarah A. Welsh ◽  
Jennifer R. Devlin ◽  
Elisa Barbieri ◽  
Deborah A. Knight ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rna Polymerase Ii ◽  
List Type ◽  
Transcriptional Responses ◽  
Anti Cancer ◽  
Phosphatase 2A ◽  
A Subunit ◽  
Spatio Temporal ◽  
Multicellular Organisms ◽  
Transcription Cycle

SUMMARYGene expression is tightly controlled by Cyclin-dependent kinases (CDKs) which regulate the RNA Polymerase II (RNAPII) transcription cycle at discrete checkpoints. RNAPII pausing is a CDK9-controlled rate-limiting process that occurs shortly after initiation and is required for spatio-temporal control of transcription in multicellular organisms. We discovered that CDK9-mediated RNAPII pause-release is functionally opposed by a protein phosphatase 2A (PP2A) complex. PP2A dynamically competes for key CDK9 substrates, DSIF and RNAPII, and is recruited to transcription pausing sites by INTS6, a subunit of the Integrator complex. INTS6 depletion disrupts the Integrator-PP2A association and confers resistance to CDK9 inhibition. This results in unrestrained activity of CDK9 and dysregulation of acute transcriptional responses. Pharmacological PP2A activation amplifies RNAPII pausing mediated by CDK9 inhibitors and synergizes therapeutically in a model of MLL-rearranged leukemia. These data demonstrate that finely-tuned gene expression relies on the delicate balance of kinase and phosphatase activity throughout the transcription cycle.HIGHLIGHTSLoss of INTS6 confers resistance to CDK9 inhibitionINTS6 recruits PP2A to Integrator and chromatinPP2A/INTS6 complexes functionally oppose CDK9PP2A/INTS6 fine-tune acute transcriptional responsesSynergistic anti-cancer activity between PP2A activators and CDK9 inhibitors

scholarly journals A Global View of Transcriptional Regulation by Nuclear Receptors: Gene Expression, Factor Localization, and DNA Sequence Analysis

2008 ◽  
Vol 6 (1) ◽  
pp. nrs.06005 ◽  
Author(s):  
Miltiadis Kininis ◽  
W. Lee Kraus
Keyword(s):  
Gene Expression ◽  
Transcriptional Regulation ◽  
Rna Polymerase Ii ◽  
Nuclear Receptors ◽  
Dna Sequences ◽  
Target Genes ◽  
Large Body ◽  
Pol Ii ◽  
Global View ◽  
Genomic Analyses

Recent genomic analyses of transcription factor binding, histone modification, and gene expression have provided a global view of transcriptional regulation by nuclear receptors (NRs) that complements an existing large body of literature on gene-specific studies. The picture emerging from these genomic studies indicates that NRs bind at promoter-proximal and promoter-distal enhancers in conjunction with other transcription factors (e.g., activator protein-1, Sp1 and FOXA1). This binding promotes the recruitment of coregulators that mediate the posttranslational modification of histones at promoters and enhancers. Ultimately, signaling through liganded NRs stimulates changes in the occupancy of RNA polymerase II (Pol II) or the activation of preloaded Pol II at target promoters. Chromosomal looping and/or Pol II tracking may underlie promoter-enhancer communication. Interestingly, the direct target genes of NR signaling represent a limited subset of all the genes regulated by NR ligands, with the rest being regulated through secondary effects. As suggested by previous gene-specific analyses, NR-mediated outcomes are highly cell type- and promoter-specific, highlighting the complexity of transcriptional regulation by NRs and the value of genomic analyses for identifying commonly shared patterns. Overall, NRs share common themes in their patterns of localization and transcriptional regulation across mammalian genomes. In this review, we provide an overview of recent advances in the understanding of NR-mediated transcription garnered from genomic analyses of gene expression, factor localization, and target DNA sequences.

scholarly journals Different Mechanisms Confer Gradual Control and Memory at Nutrient- and Stress-Regulated Genes in Yeast

2015 ◽  
Vol 35 (21) ◽  
pp. 3669-3683 ◽  
Author(s):  
Alessandro Rienzo ◽  
Daniel Poveda-Huertes ◽  
Selcan Aydin ◽  
Nicolas E. Buchler ◽  
Amparo Pascual-Ahuir ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rna Polymerase Ii ◽  
Dose Response ◽  
Dynamic Change ◽  
Regulation Of Gene Expression ◽  
High Temporal Resolution ◽  
Temporal Regulation ◽  
Response Strategies ◽  
Mitogen Activated Protein ◽  
Stress Signals

Cells respond to environmental stimuli by fine-tuned regulation of gene expression. Here we investigated the dose-dependent modulation of gene expression at high temporal resolution in response to nutrient and stress signals in yeast. TheGAL1activity in cell populations is modulated in a well-defined range of galactose concentrations, correlating with a dynamic change of histone remodeling and RNA polymerase II (RNAPII) association. This behavior is the result of a heterogeneous induction delay caused by decreasing inducer concentrations across the population. Chromatin remodeling appears to be the basis for the dynamicGAL1expression, because mutants with impaired histone dynamics show severely truncated dose-response profiles. In contrast, theGRE2promoter operates like a rapid off/on switch in response to increasing osmotic stress, with almost constant expression rates and exclusively temporal regulation of histone remodeling and RNAPII occupancy. The Gal3 inducer and the Hog1 mitogen-activated protein (MAP) kinase seem to determine the different dose-response strategies at the two promoters. Accordingly,GAL1becomes highly sensitive and dose independent if previously stimulated because of residual Gal3 levels, whereasGRE2expression diminishes upon repeated stimulation due to acquired stress resistance. Our analysis reveals important differences in the way dynamic signals create dose-sensitive gene expression outputs.

microRNAs in seeds: modified detection techniques and potential applications

2006 ◽  
Vol 84 (2) ◽  
pp. 189-198 ◽  
Author(s):  
Ruth C. Martin ◽  
Po-Pu Liu ◽  
Hiroyuki Nonogaki
Keyword(s):  
Gene Expression ◽  
Target Genes ◽  
Expression Patterns ◽  
Regulation Of Gene Expression ◽  
Environmental Signals ◽  
Detection Techniques ◽  
Potential Applications ◽  
Technical Advances ◽  
Spatio Temporal ◽  
Germinating Seeds

microRNAs (miRNAs) are small (21–24 nucleotides), single-stranded RNAs that regulate target gene expression at transcriptional and posttranscriptional levels. miRNAs play crucial roles in plant development, maintenance of homeostasis, and responses to environmental signals. miRNAs and their target genes, which can be computationally predicted in plants, are expressed in developing and germinating seeds as in other plant tissues, suggesting that miRNAs may be involved in the regulation of gene expression in seeds. Profiling multiple miRNAs expressed in developing and germinating seeds, characterizing their expression patterns in a spatio-temporal manner, and elucidating their biological functions will provide information essential for understanding the mechanisms of seed development and germination. In this review, an overview of the recent technical advances in seed miRNA research and their potential applications for plant, specifically seed, research are presented.

scholarly journals PRC1 drives Polycomb-mediated gene repression by controlling transcription initiation and burst frequency

2020 ◽  
Author(s):  
Paula Dobrinić ◽  
Aleksander T. Szczurek ◽  
Robert J. Klose
Keyword(s):  
Gene Expression ◽  
Rna Polymerase Ii ◽  
Transcription Initiation ◽  
Transcriptional Control ◽  
Target Genes ◽  
Gene Repression ◽  
Burst Frequency ◽  
Chromatin Domains ◽  
Time Resolved ◽  
Drive Gene

AbstractThe Polycomb repressive system plays a fundamental role in controlling gene expression during mammalian development. To achieve this, Polycomb repressive complexes 1 and 2 (PRC1 and PRC2) bind target genes and use histone modification-dependent feedback mechanisms to form Polycomb chromatin domains and repress transcription. The interrelatedness of PRC1 and PRC2 activity at these sites has made it difficult to discover the specific components of Polycomb chromatin domains that drive gene repression and to understand mechanistically how this is achieved. Here, by exploiting rapid degron-based approaches and time-resolved genomics we kinetically dissect Polycomb-mediated repression and discover that PRC1 functions independently of PRC2 to counteract RNA polymerase II binding and transcription initiation. Using single-cell gene expression analysis, we reveal that PRC1 acts uniformly within the cell population, and that repression is achieved by controlling transcriptional burst frequency. These important new discoveries provide a mechanistic and conceptual framework for Polycomb-dependent transcriptional control.

scholarly journals c-Myc Is Required for the ChREBP-Dependent Activation of Glucose-Responsive Genes

2010 ◽  
Vol 24 (6) ◽  
pp. 1274-1286 ◽  
Author(s):  
Pili Zhang ◽  
Mallikarjurna R. Metukuri ◽  
Sharell M. Bindom ◽  
Edward V. Prochownik ◽  
Robert M. O'Doherty ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rna Polymerase Ii ◽  
Time Course ◽  
Target Genes ◽  
Process Time ◽  
Glucose Response ◽  
Rna Pol Ii ◽  
Pol Ii ◽  
Molecular Events ◽  
Regulated Gene Expression

Abstract Glucose regulates programs of gene expression that orchestrate changes in cellular phenotype in several metabolically active tissues. Carbohydrate response element-binding protein (ChREBP) and its binding partner, Mlx, mediate glucose-regulated gene expression by binding to carbohydrate response elements on target genes, such as the prototypical glucose-responsive gene, liver-type pyruvate kinase (Pklr). c-Myc is also required for the glucose response of the Pklr gene, although the relationship between c-Myc and ChREBP has not been defined. Here we describe the molecular events of the glucose-mediated activation of Pklr and determine the effects of decreasing the activity or abundance of c-Myc on this process. Time-course chromatin immunoprecipitation revealed a set of transcription factors [hepatocyte nuclear factor (HNF)1α, HNF4α, and RNA polymerase II (Pol II)] constitutively resident on the Pklr promoter, with a relative enrichment of acetylated histones 3 and 4 in the same region of the gene. Glucose did not affect HNF1α binding or the acetylation of histones H3 or H4. By contrast, glucose promoted the recruitment of ChREBP and c-Myc and increased the occupancy of HNF4α and RNA Pol II, which were coincident with the glucose-mediated increase in transcription as determined by a nuclear run-on assay. Depletion of c-Myc activity using a small molecule inhibitor (10058-F4/1RH) abolished the glucose-mediated recruitment of HNF4α, ChREBP, and RNA Pol II, without affecting basal gene expression, histone acetylation, and HNF1α or basal HNF4α occupancy. The activation and recruitment of ChREBP to several glucose-responsive genes were blocked by 1RH, indicating a general necessity for c-Myc in this process.

scholarly journals Maternal small RNAs mediate spatial-temporal regulation of gene expression, imprinting, and seed development in Arabidopsis

2019 ◽  
Vol 116 (7) ◽  
pp. 2761-2766 ◽  
Author(s):  
Ryan C. Kirkbride ◽  
Jie Lu ◽  
Changqing Zhang ◽  
Rebecca A. Mosher ◽  
David C. Baulcombe ◽  
...  
Keyword(s):  
Gene Expression ◽  
Seed Development ◽  
Seed Coat ◽  
Target Genes ◽  
Expression Patterns ◽  
Regulation Of Gene Expression ◽  
Small Interfering Rnas ◽  
Altered Expression ◽  
Temporal Regulation ◽  
Laser Capture

Arabidopsis seed development involves maternal small interfering RNAs (siRNAs) that induce RNA-directed DNA methylation (RdDM) through the NRPD1-mediated pathway. To investigate their biological functions, we characterized siRNAs in the endosperm and seed coat that were separated by laser-capture microdissection (LCM) in reciprocal genetic crosses with an nrpd1 mutant. We also monitored the spatial-temporal activity of the NRPD1-mediated pathway on seed development using the AGO4:GFP::AGO4 (promoter:GFP::protein) reporter and promoter:GUS sensors of siRNA-mediated silencing. From these approaches, we identified four distinct groups of siRNA loci dependent on or independent of the maternal NRPD1 allele in the endosperm or seed coat. A group of maternally expressed NRPD1-siRNA loci targets endosperm-preferred genes, including those encoding AGAMOUS-LIKE (AGL) transcription factors. Using translational promoter:AGL::GUS constructs as sensors, we demonstrate that spatial and temporal expression patterns of these genes in the endosperm are regulated by the NRPD1-mediated pathway irrespective of complete silencing (AGL91) or incomplete silencing (AGL40) of these target genes. Moreover, altered expression of these siRNA-targeted genes affects seed size. We propose that the corresponding maternal siRNAs could account for parent-of-origin effects on the endosperm in interploidy and hybrid crosses. These analyses reconcile previous studies on siRNAs and imprinted gene expression during seed development.

scholarly journals CREB Promotes Beta Cell Gene Expression by Targeting Its Coactivators to Tissue-Specific Enhancers

2019 ◽  
Vol 39 (17) ◽  
Author(s):  
Sam Van de Velde ◽  
Ezra Wiater ◽  
Melissa Tran ◽  
Yousang Hwang ◽  
Philip A. Cole ◽  
...  
Keyword(s):  
Gene Expression ◽  
Beta Cell ◽  
Rna Polymerase Ii ◽  
Target Genes ◽  
Cell Function ◽  
Pancreatic Beta Cell ◽  
Specific Gene ◽  
Distal Enhancer ◽  
Determining Factors ◽  
Cell Gene Expression

ABSTRACT CREB mediates effects of cyclic AMP on cellular gene expression. Ubiquitous CREB target genes are induced following recruitment of CREB and its coactivators to promoter proximal binding sites. We found that CREB stimulates the expression of pancreatic beta cell-specific genes by targeting CBP/p300 to promoter-distal enhancer regions. Subsequent increases in histone acetylation facilitate recruitment of the coactivators CRTC2 and BRD4, leading to release of RNA polymerase II over the target gene body. Indeed, CREB-induced hyperacetylation of chromatin over superenhancers promoted beta cell-restricted gene expression, which is sensitive to inhibitors of CBP/p300 and BRD4 activity. Neurod1 appears critical in establishing nucleosome-free regions for recruitment of CREB to beta cell-specific enhancers. Deletion of a CREB-Neurod1-bound enhancer within the Lrrc10b-Syt7 superenhancer disrupted the expression of both genes and decreased beta cell function. Our results demonstrate how cross talk between signal-dependent and lineage-determining factors promotes the expression of cell-type-specific gene programs in response to extracellular cues.

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