scholarly journals Robust and efficient gene regulation through localized nuclear microenvironments

Development ◽  
2020 ◽  
Vol 147 (19) ◽  
pp. dev161430
Author(s):  
Albert Tsai ◽  
Rafael Galupa ◽  
Justin Crocker

ABSTRACTDevelopmental enhancers drive gene expression in specific cell types during animal development. They integrate signals from many different sources mediated through the binding of transcription factors, producing specific responses in gene expression. Transcription factors often bind low-affinity sequences for only short durations. How brief, low-affinity interactions drive efficient transcription and robust gene expression is a central question in developmental biology. Localized high concentrations of transcription factors have been suggested as a possible mechanism by which to use these enhancer sites effectively. Here, we discuss the evidence for such transcriptional microenvironments, mechanisms for their formation and the biological consequences of such sub-nuclear compartmentalization for developmental decisions and evolution.

2020 ◽  
Author(s):  
Alejandro Gil-Gálvez ◽  
Sandra Jiménez-Gancedo ◽  
Rafael D. Acemel ◽  
Stephanie Bertrand ◽  
Michael Schubert ◽  
...  

AbstractSignaling pathways control a large number of gene regulatory networks (GRNs) during animal development, acting as major tools for body plan formation1. Remarkably, in contrast to the large number of transcription factors present in animal genomes, only a few of these pathways operate during development2. Moreover, most of them are largely conserved along metazoan evolution3. How evolution has generated a vast diversity of animal morphologies with such a limited number of tools is still largely unknown. Here we show that gain of interconnectivity between signaling pathways, and the GRNs they control, may have played a critical contribution to the origin of vertebrates. We perturbed the retinoic acid, Wnt, FGF and Nodal signaling pathways during gastrulation in amphioxus and zebrafish and comparatively examined its effects in gene expression and cis-regulatory elements (CREs). We found that multiple developmental genes gain response to these pathways through novel CREs in the vertebrate lineage. Moreover, in contrast to amphioxus, many of these CREs are highly interconnected and respond to multiple pathways in zebrafish. Furthermore, we found that vertebrate-specific cell types are more enriched in highly interconnected genes than those tissues with more ancestral origin. Thus, the increase of CREs in vertebrates integrating inputs from different signaling pathways probably contributed to gene expression complexity and the formation of new cell types and morphological novelties in this lineage.


BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Wiruntita Chankeaw ◽  
Sandra Lignier ◽  
Christophe Richard ◽  
Theodoros Ntallaris ◽  
Mariam Raliou ◽  
...  

Abstract Background A number of studies have examined mRNA expression profiles of bovine endometrium at estrus and around the peri-implantation period of pregnancy. However, to date, these studies have been performed on the whole endometrium which is a complex tissue. Consequently, the knowledge of cell-specific gene expression, when analysis performed with whole endometrium, is still weak and obviously limits the relevance of the results of gene expression studies. Thus, the aim of this study was to characterize specific transcriptome of the three main cell-types of the bovine endometrium at day-15 of the estrus cycle. Results In the RNA-Seq analysis, the number of expressed genes detected over 10 transcripts per million was 6622, 7814 and 8242 for LE, GE and ST respectively. ST expressed exclusively 1236 genes while only 551 transcripts were specific to the GE and 330 specific to LE. For ST, over-represented biological processes included many regulation processes and response to stimulus, cell communication and cell adhesion, extracellular matrix organization as well as developmental process. For GE, cilium organization, cilium movement, protein localization to cilium and microtubule-based process were the only four main biological processes enriched. For LE, over-represented biological processes were enzyme linked receptor protein signaling pathway, cell-substrate adhesion and circulatory system process. Conclusion The data show that each endometrial cell-type has a distinct molecular signature and provide a significantly improved overview on the biological process supported by specific cell-types. The most interesting result is that stromal cells express more genes than the two epithelial types and are associated with a greater number of pathways and ontology terms.


Author(s):  
Perotti M F ◽  
Arce A L ◽  
R L Chan

Abstract Roots are the anchorage organs of plants, responsible for water and nutrient uptake, exhibiting high plasticity. Root architecture is driven by the interactions of biomolecules, including transcription factors (TFs) and hormones that are crucial players regulating root plasticity. Multiple TF families are involved in root development; some, such as ARFs and LBDs, have been well characterized, whereas others remain less investigated. In this review, we synthesize the current knowledge about the involvement of the large family of homeodomain-leucine zipper (HD-Zip) TFs in root development. This family is divided into four subfamilies (I to IV), mainly according to structural features, such as additional motifs aside from HD-Zip, as well as their size, gene structure, and expression patterns. We explored and analyzed public databases and the scientific literature regarding HD-Zip TFs in Arabidopsis and other species. Most members of the four HD-Zip subfamilies are expressed in specific cell types and several ones from each group have assigned functions in root development. Notably, a high proportion of the studied proteins are part of intricate regulation pathways involved in primary and lateral root growth and development.


2002 ◽  
Vol 50 (8) ◽  
pp. 1031-1037 ◽  
Author(s):  
Betty Ky ◽  
Paul J. Shughrue

Isotopic in situ hybridization (ISH) has been established as a uniquely powerful tool for the study of gene expression in specific cell types. This technique allows the visualization and quantification of gene expression and gene expression changes in cells. In our study of biological and molecular phenomena, we have increasingly encountered the need to detect small changes in gene expression as well as genes of low abundance, such as the oxytocin receptor (OTR) and the tuberoinfundibular peptide of 39 residues (Tip39). To increase the sensitivity of isotopic ISH for detection of rare mRNAs, we performed ISH on cryostat sections of rat hypothalamus and thalamus with 35S-labeled riboprobes and amplified the signal by hybridizing over 2 nights as well as labeling the probe with both [35S]-UTP and [35S]-ATP. These two methods of enhancement independently and in combination demonstrated a dramatic increase in signal, allowing the visualization of low levels of gene expression previously undetectable by conventional methods.


Author(s):  
Alicia M. Barnett ◽  
Jane A. Mullaney ◽  
Charlotte Hendriks ◽  
Lisa Le Borgne ◽  
Warren C. McNabb ◽  
...  

The development of alternative in vitro culture methods has increased in the last decade as three-dimensional organoids of various tissues, including those of the small and large intestines. Due to their multicellular composition, organoids offer advantages over traditionally used immortalized or primary cell lines. However, organoids must be accurate models of their tissues of origin. This study compared gene expression profiles with respect to markers of specific cell-types (stem-cells, enterocytes, goblet and enteroendocrine cells) and barrier maturation (tight junctions) of colonoid and enteroid cultures with their tissues of origin, and colonoids with enteroids. Colonoids derived from three healthy pigs formed multi-lobed structures with a monolayer of cells similar to the crypt structures in colonic tissue. Colonoid and enteroid gene expression signatures were more similar to those found for the tissues of their origin than to each other. However, relative to their derived tissues, organoids had increased gene expression levels of stem-cell markers Sox9 and Lgr5 encoding Sex determining region Y-box 9 and leucine-rich repeat-containing G-protein coupled rector 5, respectively. In contrast, expression levels of Occl and Zo1 encoding occludin and zonula occludens 1 respectively, were decreased. Expression levels of the cell lineage markers Atoh1, Cga and Muc2 encoding atonal homolog 1, chromogranin A and mucin 2 respectively, were decreased in colonoids, while Sglt1 and Apn encoding sodium-glucose transporter 1 and aminopeptidase A respectively, were decreased in enteroids. These results indicate colonoid and enteroid cultures were predominantly comprised of undifferentiated cell-types with decreased barrier maturation relative to their tissues of origin.


2019 ◽  
Author(s):  
Arnav Moudgil ◽  
Michael N. Wilkinson ◽  
Xuhua Chen ◽  
June He ◽  
Alex J. Cammack ◽  
...  

AbstractIn situ measurements of transcription factor (TF) binding are confounded by cellular heterogeneity and represent averaged profiles in complex tissues. Single cell RNA-seq (scRNA-seq) is capable of resolving different cell types based on gene expression profiles, but no technology exists to directly link specific cell types to the binding pattern of TFs in those cell types. Here, we present self-reporting transposons (SRTs) and their use in single cell calling cards (scCC), a novel assay for simultaneously capturing gene expression profiles and mapping TF binding sites in single cells. First, we show how the genomic locations of SRTs can be recovered from mRNA. Next, we demonstrate that SRTs deposited by the piggyBac transposase can be used to map the genome-wide localization of the TFs SP1, through a direct fusion of the two proteins, and BRD4, through its native affinity for piggyBac. We then present the scCC method, which maps SRTs from scRNA-seq libraries, thus enabling concomitant identification of cell types and TF binding sites in those same cells. As a proof-of-concept, we show recovery of cell type-specific BRD4 and SP1 binding sites from cultured cells. Finally, we map Brd4 binding sites in the mouse cortex at single cell resolution, thus establishing a new technique for studying TF biology in situ.


2019 ◽  
Author(s):  
Ross C. Hardison ◽  
Yu Zhang ◽  
Cheryl A. Keller ◽  
Guanjue Xiang ◽  
Elisabeth Heuston ◽  
...  

SummaryMembers of the GATA family of transcription factors play key roles in the differentiation of specific cell lineages by regulating the expression of target genes. Three GATA factors play distinct roles in hematopoietic differentiation. In order to better understand how these GATA factors function to regulate genes throughout the genome, we are studying the epigenomic and transcriptional landscapes of hematopoietic cells in a model-driven, integrative fashion. We have formed the collaborative multi-lab VISION project to conduct ValIdated Systematic IntegratiON of epigenomic data in mouse and human hematopoiesis. The epigenomic data included nuclease accessibility in chromatin, CTCF occupancy, and histone H3 modifications for twenty cell types covering hematopoietic stem cells, multilineage progenitor cells, and mature cells across the blood cell lineages of mouse. The analysis used the Integrative and Discriminative Epigenome Annotation System (IDEAS), which learns all common combinations of features (epigenetic states) simultaneously in two dimensions - along chromosomes and across cell types. The result is a segmentation that effectively paints the regulatory landscape in readily interpretable views, revealing constitutively active or silent loci as well as the loci specifically induced or repressed in each stage and lineage. Nuclease accessible DNA segments in active chromatin states were designated candidate cis-regulatory elements in each cell type, providing one of the most comprehensive registries of candidate hematopoietic regulatory elements to date. Applications of VISION resources are illustrated for regulation of genes encoding GATA1, GATA2, GATA3, and Ikaros. VISION resources are freely available from our website http://usevision.org.


Author(s):  
Pavel Georgiev ◽  
Olga Kyrchanova

In higher eukaryotes, enhancers determine the activation of developmental gene transcription in specific cell types and stages of embryogenesis. Enhancers transform the signals produced by various transcription factors within a given cell, activating the transcription of the targeted genes. Often, developmental genes can be associated with dozens of enhancers, some of which are located at large distances from the promoters that they regulate. Currently, the mechanisms that underly the specific distance interactions between enhancers and promoters remain unknown. This review describes the properties and activities of enhancers and discusses the mechanisms of distance interactions and potential proteins involved in this process.


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