scholarly journals Activation-Dependent TRAF3 Exon 8 Alternative Splicing Is Controlled by CELF2 and hnRNP C Binding to an Upstream Intronic Element

2016 ◽  
Vol 37 (7) ◽  
Author(s):  
Astrid-Solveig Schultz ◽  
Marco Preussner ◽  
Mario Bunse ◽  
Rotem Karni ◽  
Florian Heyd

ABSTRACT Cell-type-specific and inducible alternative splicing has a fundamental impact on regulating gene expression and cellular function in a variety of settings, including activation and differentiation. We have recently shown that activation-induced skipping of TRAF3 exon 8 activates noncanonical NF-κB signaling upon T cell stimulation, but the regulatory basis for this splicing event remains unknown. Here we identify cis- and trans-regulatory elements rendering this splicing switch activation dependent and cell type specific. The cis-acting element is located 340 to 440 nucleotides upstream of the regulated exon and acts in a distance-dependent manner, since altering the location reduces its activity. A small interfering RNA screen, followed by cross-link immunoprecipitation and mutational analyses, identified CELF2 and hnRNP C as trans-acting factors that directly bind the regulatory sequence and together mediate increased exon skipping in activated T cells. CELF2 expression levels correlate with TRAF3 exon skipping in several model systems, suggesting that CELF2 is the decisive factor, with hnRNP C being necessary but not sufficient. These data suggest an interplay between CELF2 and hnRNP C as the mechanistic basis for activation-dependent alternative splicing of TRAF3 exon 8 and additional exons and uncover an intronic splicing silencer whose full activity depends on the precise location more than 300 nucleotides upstream of the regulated exon.

2021 ◽  
Vol 7 (20) ◽  
pp. eabf1444
Author(s):  
James D. Hocker ◽  
Olivier B. Poirion ◽  
Fugui Zhu ◽  
Justin Buchanan ◽  
Kai Zhang ◽  
...  

Misregulated gene expression in human hearts can result in cardiovascular diseases that are leading causes of mortality worldwide. However, the limited information on the genomic location of candidate cis-regulatory elements (cCREs) such as enhancers and promoters in distinct cardiac cell types has restricted the understanding of these diseases. Here, we defined >287,000 cCREs in the four chambers of the human heart at single-cell resolution, which revealed cCREs and candidate transcription factors associated with cardiac cell types in a region-dependent manner and during heart failure. We further found cardiovascular disease–associated genetic variants enriched within these cCREs including 38 candidate causal atrial fibrillation variants localized to cardiomyocyte cCREs. Additional functional studies revealed that two of these variants affect a cCRE controlling KCNH2/HERG expression and action potential repolarization. Overall, this atlas of human cardiac cCREs provides the foundation for illuminating cell type–specific gene regulation in human hearts during health and disease.


2021 ◽  
Author(s):  
Tulsi Patel ◽  
Jennifer Hammelman ◽  
Michael Closser ◽  
David K. Gifford ◽  
Hynek Wichterle

SummaryBuilding a nervous system is a protracted process that starts with the specification of individual neuron types and ends with the formation of mature neural circuits. The molecular mechanisms that regulate the temporal progression of maturation in individual cell types remain poorly understood. In this work, we have mapped the gene expression and chromatin accessibility changes in mouse spinal motor neurons throughout their lifetimes. We found that both motor neuron gene expression and putative regulatory elements are dynamic during the first three weeks of postnatal life, when motor circuits are maturing. Genes that are up-regulated during this time contribute to adult motor neuron diversity and function. Almost all of the chromatin regions that gain accessibility during maturation are motor neuron specific, yet a majority of the transcription factor binding motifs enriched in these regions are shared with other mature neurons. Collectively, these findings suggest that a core transcriptional program operates in a context-dependent manner to access cell-type-specific cis-regulatory systems associated with maturation genes. Discovery of general principles governing neuronal maturation might inform methods for transcriptional reprogramming of neuronal age and for improved modelling of age-related neurodegenerative diseases.


Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. SCI-14-SCI-14
Author(s):  
Joanna Wysocka

Abstract Interactions between the genome and its cellular and signaling environments, which ultimately occur at the level of chromatin, are the key to comprehending how cell-type-specific gene expression patterns arise and are maintained during development or are misregulated in disease. Central to the cell type-specific transcriptional regulation are distal cis-regulatory elements called enhancers, which function in a modular way to provide exquisite spatiotemporal control of gene expression during development. We are using a combination of genomic, genetic, biochemical, and single-cell approaches to investigate how enhancers are activated in response to developmental stimuli, how they communicate with target promoters over large genomic distances to regulate transcriptional outputs, what is the role of chromatin modification and remodeling in facilitating or restricting enhancer activity and how regulatory sequence change leads to the phenotypic divergence in humans. I will discuss our latest results on the mechanisms underlying enhancer function and gene regulation in development and disease. Disclosures No relevant conflicts of interest to declare.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Rongxin Fang ◽  
Sebastian Preissl ◽  
Yang Li ◽  
Xiaomeng Hou ◽  
Jacinta Lucero ◽  
...  

AbstractIdentification of the cis-regulatory elements controlling cell-type specific gene expression patterns is essential for understanding the origin of cellular diversity. Conventional assays to map regulatory elements via open chromatin analysis of primary tissues is hindered by sample heterogeneity. Single cell analysis of accessible chromatin (scATAC-seq) can overcome this limitation. However, the high-level noise of each single cell profile and the large volume of data pose unique computational challenges. Here, we introduce SnapATAC, a software package for analyzing scATAC-seq datasets. SnapATAC dissects cellular heterogeneity in an unbiased manner and map the trajectories of cellular states. Using the Nyström method, SnapATAC can process data from up to a million cells. Furthermore, SnapATAC incorporates existing tools into a comprehensive package for analyzing single cell ATAC-seq dataset. As demonstration of its utility, SnapATAC is applied to 55,592 single-nucleus ATAC-seq profiles from the mouse secondary motor cortex. The analysis reveals ~370,000 candidate regulatory elements in 31 distinct cell populations in this brain region and inferred candidate cell-type specific transcriptional regulators.


eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Sinisa Hrvatin ◽  
Christopher P Tzeng ◽  
M Aurel Nagy ◽  
Hume Stroud ◽  
Charalampia Koutsioumpa ◽  
...  

Enhancers are the primary DNA regulatory elements that confer cell type specificity of gene expression. Recent studies characterizing individual enhancers have revealed their potential to direct heterologous gene expression in a highly cell-type-specific manner. However, it has not yet been possible to systematically identify and test the function of enhancers for each of the many cell types in an organism. We have developed PESCA, a scalable and generalizable method that leverages ATAC- and single-cell RNA-sequencing protocols, to characterize cell-type-specific enhancers that should enable genetic access and perturbation of gene function across mammalian cell types. Focusing on the highly heterogeneous mammalian cerebral cortex, we apply PESCA to find enhancers and generate viral reagents capable of accessing and manipulating a subset of somatostatin-expressing cortical interneurons with high specificity. This study demonstrates the utility of this platform for developing new cell-type-specific viral reagents, with significant implications for both basic and translational research.


2021 ◽  
Author(s):  
Firat Terzi ◽  
Johannes Knabbe ◽  
Sidney B. Cambridge

SummaryGenetic engineering of quintuple transgenic brain tissue was used to establish a low background, Cre-dependent version of the inducible Tet-On system for fast, cell type-specific transgene expression in vivo. Co-expression of a constitutive, Cre-dependent fluorescent marker selectively allowed single cell analyses before and after inducible, tet-dependent transgene expression. Here, we used this method for acute, high-resolution manipulation of neuronal activity in the living brain. Single induction of the potassium channel Kir2.1 produced cell type-specific silencing within hours that lasted for at least three days. Longitudinal in vivo imaging of spontaneous calcium transients and neuronal morphology demonstrated that prolonged silencing did not alter spine densities or synaptic input strength. Furthermore, selective induction of Kir2.1 in parvalbumin interneurons increased the activity of surrounding neurons in a distance-dependent manner. This high-resolution, inducible interference and interval imaging of individual cells (high I5, ‘HighFive’) method thus allows visualizing temporally precise, genetic perturbations of defined cells.


2020 ◽  
Author(s):  
Nil Aygün ◽  
Angela L. Elwell ◽  
Dan Liang ◽  
Michael J. Lafferty ◽  
Kerry E. Cheek ◽  
...  

SummaryInterpretation of the function of non-coding risk loci for neuropsychiatric disorders and brain-relevant traits via gene expression and alternative splicing is mainly performed in bulk post-mortem adult tissue. However, genetic risk loci are enriched in regulatory elements of cells present during neocortical differentiation, and regulatory effects of risk variants may be masked by heterogeneity in bulk tissue. Here, we map e/sQTLs and allele specific expression in primary human neural progenitors (n=85) and their sorted neuronal progeny (n=74). Using colocalization and TWAS, we uncover cell-type specific regulatory mechanisms underlying risk for these traits.


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