scholarly journals Variation in the modality of a yeast signaling pathway is mediated by a single regulator

2017 ◽  
Author(s):  
Julius Palme ◽  
Jue Wang ◽  
Michael Springer
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Natural Variation ◽  
Signaling Networks ◽  
Natural Environments ◽  
Bet Hedging ◽  
Natural Genetic Variation ◽  
Bimodal Gene ◽  
Galactose Utilization ◽  
And Function

AbstractBimodal gene expression by genetically identical cells is a pervasive feature of signaling networks. In the galactose-utilization (GAL) pathway ofSaccharomyces cerevisiae, induction can be unimodal or bimodal depending on natural genetic variation and pre-induction conditions. Here, we find that this variation of modality is regulated by an interplay between two features of the pathway response, the fraction of cells that are in the induced subpopulation and their expression level. Combined, the variations in these features are sufficient to explain the observed effects of natural variation and pre-induction conditions on the modality of induction in both mechanistic and phenomenological models. Both natural variation and pre-induction conditions act by modulating the expression and function of the galactose sensorGAL3. The ability to alter modality may allow organisms to adapt their level of “bet hedging” to the conditions they experience, and thus help optimize fitness in complex, fluctuating natural environments.

scholarly journals Variation in the modality of a yeast signaling pathway is mediated by a single regulator

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Julius Palme ◽  
Jue Wang ◽  
Michael Springer
Keyword(s):  
Gene Expression ◽  
Signaling Networks ◽  
Complex Environments ◽  
Bet Hedging ◽  
Rapid Adaptation ◽  
Natural Genetic Variation ◽  
Single Protein ◽  
Natural Isolates ◽  
Bimodal Gene ◽  
Galactose Utilization

Bimodal gene expression by genetically identical cells is a pervasive feature of signaling networks, and has been suggested to allow organisms to hedge their "bets" in uncertain conditions. In the galactose-utilization (GAL) pathway of Saccharomyces cerevisiae, gene induction is unimodal or bimodal depending on natural genetic variation and pre-induction conditions. Here, we find that this variation in modality arises from regulation of two features of the pathway response: the fraction of cells that show induction, and their level of expression. GAL3, the galactose sensor, controls the fraction of induced cells, and titrating its expression is sufficient to control modality; moreover, all the observed differences in modality between different pre-induction conditions and amongst natural isolates can be explained by changes in GAL3's regulation and activity. The ability to switch modality by tuning the activity of a single protein may allow rapid adaptation of bet hedging to maximize fitness in complex environments.

scholarly journals Structure of the yeast Swi/Snf complex in a nucleosome free state

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Chengcheng Wang ◽  
Zhouyan Guo ◽  
Xiechao Zhan ◽  
Fenghua Yang ◽  
Mingxuan Wu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Structural Features ◽  
Free State ◽  
Chromatin Remodelers ◽  
Chromatin Architecture ◽  
And Function ◽  
Base Module

Abstract SWI/SNF remodelers play a key role in regulating chromatin architecture and gene expression. Here, we report the cryo-EM structure of the Saccharomyces cerevisiae Swi/Snf complex in a nucleosome-free state. The structure consists of a stable triangular base module and a flexible Arp module. The conserved subunits Swi1 and Swi3 form the backbone of the complex and closely interact with other components. Snf6, which is specific for yeast Swi/Snf complex, stabilizes the binding of the ATPase-containing subunit Snf2 to the base module. Comparison of the yeast Swi/Snf and RSC complexes reveals conserved structural features that govern the assembly and function of these two subfamilies of chromatin remodelers. Our findings complement those from recent structures of the yeast and human chromatin remodelers and provide further insights into the assembly and function of the SWI/SNF remodelers.

scholarly journals Acute condensin depletion causes genome decompaction without altering the level of global gene expression in Saccharomyces cerevisiae

2017 ◽  
Author(s):  
Matthew Robert Paul ◽  
Tovah Elise Markowitz ◽  
Andreas Hochwagen ◽  
Sevinç Ercan
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Genome Organization ◽  
Large Scale ◽  
Global Gene Expression ◽  
Higher Order ◽  
Gene Clustering ◽  
Global Changes ◽  
Chromatin Compaction ◽  
And Function

AbstractCondensins are broadly conserved chromosome organizers that function in chromatin compaction and transcriptional regulation, but to what extent these two functions are linked has remained unclear. Here, we analyzed the effect of condensin inactivation on genome compaction and global gene expression in the yeast Saccharomyces cerevisiae. Spike-in-controlled 3C-seq analysis revealed that acute condensin inactivation leads to a global decrease in close-range chromosomal interactions as well as more specific losses of homotypic tRNA gene clustering. In addition, a condensin-rich topologically associated domain between the ribosomal DNA and the centromere on chromosome XII is lost upon condensin inactivation. Unexpectedly, these large-scale changes in chromosome architecture are not associated with global changes in transcript levels as determined by spike-in-controlled mRNA-seq analysis. Our data suggest that the global transcriptional program of S. cerevisiae is resistant to condensin inactivation and the associated profound changes in genome organization.Significance StatementGene expression occurs in the context of higher-order chromatin organization, which helps compact the genome within the spatial constraints of the nucleus. To what extent higher-order chromatin compaction affects gene expression remains unknown. Here, we show that gene expression and genome compaction can be uncoupled in the single-celled model eukaryote Saccharomyces cerevisiae. Inactivation of the conserved condensin complex, which also organizes the human genome, leads to broad genome decompaction in this organism. Unexpectedly, this reorganization has no immediate effect on the transcriptome. These findings indicate that the global gene expression program is robust to large-scale changes in genome architecture in yeast, shedding important new light on the evolution and function of genome organization in gene regulation.

scholarly journals Transcriptomic characterization of signaling pathways associated with osteoblastic differentiation of MC-3T3E1 cells

2018 ◽  
Author(s):  
Louis M. Luttrell ◽  
Moahad S. Dar ◽  
Diane Gesty-Palmer ◽  
Hesham M. El-Shewy ◽  
Katherine M. Robinson ◽  
...  
Keyword(s):  
Gene Expression ◽  
Osteoblast Differentiation ◽  
Mechanical Load ◽  
Osteoblastic Differentiation ◽  
Signaling Networks ◽  
Mineral Density ◽  
Pathways Analysis ◽  
And Function ◽  
Osteoblast Maturation

AbstractBone remodeling involves the coordinated actions of osteoclasts, which resorb the calcified bony matrix, and osteoblasts, which refill erosion pits created by osteoclasts to restore skeletal integrity and adapt to changes in mechanical load. Osteoblasts are derived from pluripotent mesenchymal stem cell precursors, which undergo differentiation under the influence of a host of local and environmental cues. To characterize the autocrine/paracrine signaling networks associated with osteoblast maturation and function, we performed gene network analysis using complementary “agnostic” DNA microarray and “targeted” NanoString™ nCounter datasets derived from murine MC3T3-E1 cells induced to undergo synchronized osteoblastic differentiation in vitro. Pairwise datasets representing changes in gene expression associated with growth arrest (day 2 to 5 in culture), differentiation (day 5 to 10 in culture), and osteoblast maturation (day 10 to 28 in culture) were analyzed using Ingenuity Systems™ Pathways Analysis to generate predictions about signaling pathway activity based on the temporal sequence of changes in target gene expression. Our data indicate that some pathways known to be involved in osteoblast differentiation, e.g. Wnt/β-catenin signaling, are most active early in the process, while others, e.g. TGFβ/BMP, cytokine/JAK-STAT and TNFα/RANKL signaling, increase in activity as differentiation progresses. Collectively, these pathways contribute to the sequential expression of genes involved in the synthesis and mineralization of extracellular matrix. These results provide insight into the temporal coordination and complex interplay between signaling networks controlling gene expression during osteoblast differentiation. A more complete understanding of these processes may aid the discovery of novel methods to promote osteoblast development for the trea™ent of conditions characterized by low bone mineral density.

scholarly journals Towards an understanding of cell-specific functions of signal-dependent transcription factors

2013 ◽  
Vol 51 (3) ◽  
pp. T37-T50 ◽  
Author(s):  
Dawn X Zhang ◽  
Christopher K Glass
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Hormone Receptors ◽  
Wide Spectrum ◽  
Transcriptional Responses ◽  
Natural Genetic Variation ◽  
Surface Receptors ◽  
A Genome ◽  
And Function

The ability to regulate gene expression in a cell-specific manner is a feature of many broadly expressed signal-dependent transcription factors (SDTFs), including nuclear hormone receptors and transcription factors that are activated by cell surface receptors for extracellular signals. As the most plastic cells of the hematopoietic system, macrophages are responsive to a wide spectrum of regulatory molecules and provide a robust model system for investigation of the basis for cell-specific transcriptional responses at a genome-wide level. Here, focusing on recent studies in macrophages, we review the evidence suggesting a model in which cell-specific actions of SDTFs are the consequence of priming functions of lineage determining transcription factors. We also discuss recent findings relating lineage-determining and SDTF activity to alterations in the epigenetic landscape as well as the production and function of enhancer RNAs. These findings have implications for the understanding of how natural genetic variation impacts cell-specific programs of gene expression and suggest new approaches for altering gene expressionin vivo.

scholarly journals Roles of HIF and 2-Oxoglutarate-Dependent Dioxygenases in Controlling Gene Expression in Hypoxia

Cancers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 350
Author(s):  
Julianty Frost ◽  
Mark Frost ◽  
Michael Batie ◽  
Hao Jiang ◽  
Sonia Rocha
Keyword(s):  
Gene Expression ◽  
Hypoxia Inducible Factor ◽  
Transcriptional Regulator ◽  
Hydroxylase Activity ◽  
Control Of Gene Expression ◽  
Prolyl Hydroxylases ◽  
Chromatin Organisation ◽  
Sense And Respond ◽  
Almost All ◽  
And Function

Hypoxia—reduction in oxygen availability—plays key roles in both physiological and pathological processes. Given the importance of oxygen for cell and organism viability, mechanisms to sense and respond to hypoxia are in place. A variety of enzymes utilise molecular oxygen, but of particular importance to oxygen sensing are the 2-oxoglutarate (2-OG) dependent dioxygenases (2-OGDs). Of these, Prolyl-hydroxylases have long been recognised to control the levels and function of Hypoxia Inducible Factor (HIF), a master transcriptional regulator in hypoxia, via their hydroxylase activity. However, recent studies are revealing that dioxygenases are involved in almost all aspects of gene regulation, including chromatin organisation, transcription and translation. We highlight the relevance of HIF and 2-OGDs in the control of gene expression in response to hypoxia and their relevance to human biology and health.

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