Tissue-specific ramp sequences correspond with increased gene expression in humans and SARS-CoV-2

Abstract Translational ramp sequences are essential regulatory elements that have yet to be characterized in specific tissues. Ramp sequences increase gene expression by evenly spacing ribosomes and slowing initial translation. Therefore, the relative codon adaptiveness within different tissues changes the existence of a ramp sequence without altering the underlying genetic code. Here, we present the first comprehensive analysis of tissue and cell type-specific ramp sequences, and report 3,108 genes with ramp sequences that change between tissues and cell types. The Ramp Atlas (https://ramps.byu.edu/) is an accompanying web portal that allows researchers to query ramp sequences in 18,388 genes across 62 tissues and 66 cell types. We also identified seven SARS-CoV-2 genes and seven human SARS-CoV-2 entry factor genes with tissue-specific ramp sequences that may help explain viral proliferation within those tissues. We anticipate that The Ramp Atlas will facilitate future tissue-specific ramp sequence analyses to develop targeted therapeutics for human disease.

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A scalable platform for the development of cell-type-specific viral drivers

eLife ◽

10.7554/elife.48089 ◽

2019 ◽

Vol 8 ◽

Cited By ~ 12

Author(s):

Sinisa Hrvatin ◽

Christopher P Tzeng ◽

M Aurel Nagy ◽

Hume Stroud ◽

Charalampia Koutsioumpa ◽

...

Keyword(s):

Gene Expression ◽

Heterologous Gene Expression ◽

High Specificity ◽

Cell Types ◽

Regulatory Elements ◽

Cell Type ◽

Cell Type Specificity ◽

Cell Type Specific ◽

The Many ◽

Dna Regulatory Elements

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.

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Analysis of putative cis-regulatory elements regulating blood pressure variation

10.1101/820522 ◽

2019 ◽

Author(s):

Priyanka Nandakumar ◽

Dongwon Lee ◽

Thomas J. Hoffmann ◽

Georg B. Ehret ◽

Dan Arking ◽

...

Keyword(s):

Gene Expression ◽

Blood Pressure ◽

Cell Types ◽

Regulatory Elements ◽

Open Chromatin ◽

Genome Wide Association Studies ◽

Cell Type ◽

Functional Scores ◽

Cell Type Specific ◽

Different Tissues

AbstractHundreds of loci have been associated with blood pressure traits from many genome-wide association studies. We identified an enrichment of these loci in aorta and tibial artery expression quantitative trait loci in our previous work in ∼100,000 Genetic Epidemiology Research on Aging (GERA) study participants. In the present study, we subsequently focused on determining putative regulatory regions for these and other tissues of relevance to blood pressure, to both fine-map these loci by pinpointing genes and variants of functional interest within them, and to identify any novel genes.We constructed maps of putative cis-regulatory elements using publicly available open chromatin data for the heart, aorta and tibial arteries, and multiple kidney cell types. Sequence variants within these regions may be evaluated quantitatively for their tissue- or cell-type-specific regulatory impact using deltaSVM functional scores, as described in our previous work. In order to identify genes of interest, we aggregate these variants in these putative cis-regulatory elements within 50Kb of the start or end of genes considered as “expressed” in these tissues or cell types using publicly available gene expression data, and use the deltaSVM scores as weights in the well-known group-wise sequence kernel association test (SKAT). We test for association with both blood pressure traits as well as expression within these tissues or cell types of interest, and identify several genes, including MTHFR, C10orf32, CSK, NOV, ULK4, SDCCAG8, SCAMP5, RPP25, HDGFRP3, VPS37B, and PPCDC. Although our study centers on blood pressure traits, we additionally examined two known genes, SCN5A and NOS1AP involved in the cardiac trait QT interval, in the Atherosclerosis Risk in Communities Study (ARIC), as a positive control, and observed an expected heart-specific effect. Thus, our method may be used to identify variants and genes for further functional testing using tissue- or cell-type-specific putative regulatory information.Author SummarySequence change in genes (“variants”) are linked to the presence and severity of different traits or diseases. However, as genes may be expressed in different tissues and at different times and degrees, using this information is expected to more accurately identify genes of interest. Variants within the genes are essential, but also in the sequences (“regulatory elements”) that control the genes’ expression in different tissues or cell types. In this study, we aim to use this information about expression and variants potentially involved in gene expression regulation to better pinpoint genes and variants in regulatory elements of interest for blood pressure regulation. We do so by taking advantage of such data that are publicly available, and use methods to combine information about variants in aggregate within a gene’s putative regulatory elements in tissues thought to be relevant for blood pressure, and identify several genes, meant to enable experimental follow-up.

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A human cell atlas of fetal chromatin accessibility

Science ◽

10.1126/science.aba7612 ◽

2020 ◽

Vol 370 (6518) ◽

pp. eaba7612 ◽

Cited By ~ 1

Author(s):

Silvia Domcke ◽

Andrew J. Hill ◽

Riza M. Daza ◽

Junyue Cao ◽

Diana R. O’Day ◽

...

Keyword(s):

Gene Expression ◽

Human Cell ◽

Single Cells ◽

Complex Trait ◽

Cell Types ◽

Regulatory Elements ◽

Chromatin Accessibility ◽

Cell Type ◽

Cell Type Specific

The chromatin landscape underlying the specification of human cell types is of fundamental interest. We generated human cell atlases of chromatin accessibility and gene expression in fetal tissues. For chromatin accessibility, we devised a three-level combinatorial indexing assay and applied it to 53 samples representing 15 organs, profiling ~800,000 single cells. We leveraged cell types defined by gene expression to annotate these data and cataloged hundreds of thousands of candidate regulatory elements that exhibit cell type–specific chromatin accessibility. We investigated the properties of lineage-specific transcription factors (such as POU2F1 in neurons), organ-specific specializations of broadly distributed cell types (such as blood and endothelial), and cell type–specific enrichments of complex trait heritability. These data represent a rich resource for the exploration of in vivo human gene regulation in diverse tissues and cell types.

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PESCA: A scalable platform for the development of cell-type-specific viral drivers

10.1101/570895 ◽

2019 ◽

Cited By ~ 3

Author(s):

Sinisa Hrvatin ◽

Christopher P. Tzeng ◽

M. Aurel Nagy ◽

Hume Stroud ◽

Charalampia Koutsioumpa ◽

...

Keyword(s):

Gene Expression ◽

Heterologous Gene Expression ◽

Single Cells ◽

Cell Types ◽

Regulatory Elements ◽

Functional Evaluation ◽

Cell Type ◽

Cell Type Specificity ◽

Enhancer Activity ◽

Cell Type Specific

AbstractEnhancers 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.One sentence summaryHighly paralleled functional evaluation of enhancer activity in single cells generates new cell-type-specific tools with broad medical and scientific applications.

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A probabilistic framework to dissect functional cell-type-specific regulatory elements and risk loci underlying the genetics of complex traits

10.1101/059345 ◽

2016 ◽

Cited By ~ 4

Author(s):

Yue Li ◽

Jose Davila-Velderrain ◽

Manolis Kellis

Keyword(s):

Complex Traits ◽

Large Scale ◽

Learning Algorithm ◽

Cell Types ◽

Regulatory Elements ◽

Probabilistic Framework ◽

Cell Type ◽

Tissue Specific ◽

Functional Variants ◽

Cell Type Specific

AbstractDissecting the physiological circuitry underlying diverse human complex traits associated with heritable common mutations is an ongoing effort. The primary challenge involves identifying the relevant cell types and the causal variants among the vast majority of the associated mutations in the noncoding regions. To address this challenge, we developed an efficient probabilistic framework. First, we propose a sparse group-guided learning algorithm to infer cell-type-specific enrichments. Second, we propose a fine-mapping Bayesian model that incorporates as Bayesian priors the sparse enrichments to infer risk variants. Using the proposed framework to analyze 32 complex human traits revealed meaningful tissue-specific epigenomic enrichments indicative of the relevant disease pathologies. The prioritized variants exhibit prominent tissue-specific epigenomic signatures and significant enrichments for eQTL and conserved elements. Together, we demonstrate the general benefits of the proposed integrative framework in elucidating meaningful tissue-specific epigenomic elements from large-scale correlated annotations and the implicated functional variants for future experimental interrogation.

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Evolution of regulatory signatures in primate cortical neurons at cell type resolution

10.1101/2020.07.24.219881 ◽

2020 ◽

Author(s):

Alexey Kozlenkov ◽

Marit W. Vermunt ◽

Pasha Apontes ◽

Junhao Li ◽

Ke Hao ◽

...

Keyword(s):

Gene Expression ◽

Cerebral Cortex ◽

Human Brain ◽

Brain Tissue ◽

Cell Types ◽

Regulatory Elements ◽

Autism Spectrum ◽

Evolutionary Divergence ◽

Cell Type ◽

Cell Type Specific

ABSTRACTThe human cerebral cortex contains many cell types that likely underwent independent functional changes during evolution. However, cell type-specific regulatory landscapes in the cortex remain largely unexplored. Here we report epigenomic and transcriptomic analyses of the two main cortical neuronal subtypes, glutamatergic projection neurons and GABAergic interneurons, in human, chimpanzee and rhesus macaque. Using genome-wide profiling of the H3K27ac histone modification, we identify neuron-subtype-specific regulatory elements that previously went undetected in bulk brain tissue samples. Human-specific regulatory changes are uncovered in multiple genes, including those associated with language, autism spectrum disorder and drug addiction. We observe preferential evolutionary divergence in neuron-subtype-specific regulatory elements and show that a substantial fraction of pan-neuronal regulatory elements undergo subtype-specific evolutionary changes. This study sheds light on the interplay between regulatory evolution and cell-type-dependent gene expression programs, and provides a resource for further exploration of human brain evolution and function.SIGNIFICANCEThe cerebral cortex of the human brain is a highly complex, heterogeneous tissue that contains many cell types which are exquisitely regulated at the level of gene expression by non-coding regulatory elements, presumably, in a cell-type-dependent manner. However, assessing the regulatory elements in individual cell types is technically challenging, and therefore, most of the previous studies on gene regulation were performed with bulk brain tissue. Here we analyze two major types of neurons isolated from the cerebral cortex of humans, chimpanzees and rhesus macaques, and report complex patterns of cell-type-specific evolution of the regulatory elements in numerous genes. Many genes with evolving regulation are implicated in language abilities as well as psychiatric disorders.

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Glucocorticoid receptor collaborates with pioneer factors and AP-1 to execute genome-wide regulation

10.1101/2021.06.01.444518 ◽

2021 ◽

Author(s):

Erin M Wissink ◽

Delsy M. Martinez ◽

Kirk T. Ehmsen ◽

Keith R. Yamamoto ◽

John T Lis

Keyword(s):

Gene Expression ◽

Transcriptional Regulation ◽

Glucocorticoid Receptor ◽

Human Cancer ◽

Cell Types ◽

Regulatory Elements ◽

Cell Type ◽

Glucocorticoid Treatment ◽

Cell Type Specific ◽

Pioneer Factors

The glucocorticoid receptor (GR) regulates transcription through binding to specific DNA motifs, particularly at enhancers. While the motif to which it binds is constant across cell types, GR has cell type-specific binding at genomic loci, resulting in regulation of different genes. The presence of other bound transcription factors (TFs) is hypothesized to strongly influence where GR binds. Here, we addressed the roles of other TFs in the glucocorticoid response by comparing changes in GR binding and nascent transcription at promoters and distal candidate cis-regulatory elements (CCREs) in two distinct human cancer cell types. We found that after glucocorticoid treatment, GR binds to thousands of genomic loci that are primarily outside of promoter regions and are potentially enhancers. The majority of these GR binding sites are cell-type specific, and they are associated with pioneer factor binding. A small fraction of GR occupied regions (GORs) displayed increased bidirectional nascent transcription, which is a characteristic of many active enhancers, after glucocorticoid treatment. Non-promoter GORs with increased transcription were specifically enriched for AP-1 binding prior to glucocorticoid treatment. These results support a model of transcriptional regulation in which multiple classes of TFs are required. The pioneer factors increase chromatin accessibility, facilitating the binding of GR and additional factors. AP-1 binding poises a fraction of accessible sites to be rapidly transcribed upon glucocorticoid-induced GR binding. The coordinated activity of multiple TFs then results in cell type-specific changes in gene expression. We anticipate that many models of inducible gene expression also require multiple distinct TFs that act at multiple steps of transcriptional regulation.

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Integrative analysis of 3604 GWAS reveals multiple novel cell type-specific regulatory associations

Genome Biology ◽

10.1186/s13059-021-02560-3 ◽

2022 ◽

Vol 23 (1) ◽

Author(s):

Charles E. Breeze ◽

Eric Haugen ◽

Alex Reynolds ◽

Andrew Teschendorff ◽

Jenny van Dongen ◽

...

Keyword(s):

Disease Risk ◽

Cell Types ◽

Regulatory Elements ◽

Integrative Analysis ◽

Cell Type ◽

Web Tool ◽

Tissue Specific ◽

Chromatin States ◽

Disease Aetiology ◽

Cell Type Specific

Abstract Background Genome-wide association study (GWAS) single nucleotide polymorphisms (SNPs) are known to preferentially co-locate to active regulatory elements in tissues and cell types relevant to disease aetiology. Further characterisation of associated cell type-specific regulation can broaden our understanding of how GWAS signals may contribute to disease risk. Results To gain insight into potential functional mechanisms underlying GWAS associations, we developed FORGE2 (https://forge2.altiusinstitute.org/), which is an updated version of the FORGE web tool. FORGE2 uses an expanded atlas of cell type-specific regulatory element annotations, including DNase I hotspots, five histone mark categories and 15 hidden Markov model (HMM) chromatin states, to identify tissue- and cell type-specific signals. An analysis of 3,604 GWAS from the NHGRI-EBI GWAS catalogue yielded at least one significant disease/trait-tissue association for 2,057 GWAS, including > 400 associations specific to epigenomic marks in immune tissues and cell types, > 30 associations specific to heart tissue, and > 60 associations specific to brain tissue, highlighting the key potential of tissue- and cell type-specific regulatory elements. Importantly, we demonstrate that FORGE2 analysis can separate previously observed accessible chromatin enrichments into different chromatin states, such as enhancers or active transcription start sites, providing a greater understanding of underlying regulatory mechanisms. Interestingly, tissue-specific enrichments for repressive chromatin states and histone marks were also detected, suggesting a role for tissue-specific repressed regions in GWAS-mediated disease aetiology. Conclusion In summary, we demonstrate that FORGE2 has the potential to uncover previously unreported disease-tissue associations and identify new candidate mechanisms. FORGE2 is a transparent, user-friendly web tool for the integrative analysis of loci discovered from GWAS.

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Histone modifications form a cell-type-specific chromosomal bar code that persists through the cell cycle

Scientific Reports ◽

10.1038/s41598-021-82539-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

John A. Halsall ◽

Simon Andrews ◽

Felix Krueger ◽

Charlotte E. Rutledge ◽

Gabriella Ficz ◽

...

Keyword(s):

Gene Expression ◽

Cell Cycle ◽

Histone Modifications ◽

Expression Patterns ◽

Cell Types ◽

Cell Type ◽

Bar Code ◽

Genes Encoding ◽

Cell Type Specific ◽

Rolling Windows

AbstractChromatin configuration influences gene expression in eukaryotes at multiple levels, from individual nucleosomes to chromatin domains several Mb long. Post-translational modifications (PTM) of core histones seem to be involved in chromatin structural transitions, but how remains unclear. To explore this, we used ChIP-seq and two cell types, HeLa and lymphoblastoid (LCL), to define how changes in chromatin packaging through the cell cycle influence the distributions of three transcription-associated histone modifications, H3K9ac, H3K4me3 and H3K27me3. We show that chromosome regions (bands) of 10–50 Mb, detectable by immunofluorescence microscopy of metaphase (M) chromosomes, are also present in G1 and G2. They comprise 1–5 Mb sub-bands that differ between HeLa and LCL but remain consistent through the cell cycle. The same sub-bands are defined by H3K9ac and H3K4me3, while H3K27me3 spreads more widely. We found little change between cell cycle phases, whether compared by 5 Kb rolling windows or when analysis was restricted to functional elements such as transcription start sites and topologically associating domains. Only a small number of genes showed cell-cycle related changes: at genes encoding proteins involved in mitosis, H3K9 became highly acetylated in G2M, possibly because of ongoing transcription. In conclusion, modified histone isoforms H3K9ac, H3K4me3 and H3K27me3 exhibit a characteristic genomic distribution at resolutions of 1 Mb and below that differs between HeLa and lymphoblastoid cells but remains remarkably consistent through the cell cycle. We suggest that this cell-type-specific chromosomal bar-code is part of a homeostatic mechanism by which cells retain their characteristic gene expression patterns, and hence their identity, through multiple mitoses.

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Genetic influences on cell type specific gene expression and splicing during neurogenesis elucidate regulatory mechanisms of brain traits

10.1101/2020.10.21.349019 ◽

2020 ◽

Author(s):

Nil Aygün ◽

Angela L. Elwell ◽

Dan Liang ◽

Michael J. Lafferty ◽

Kerry E. Cheek ◽

...

Keyword(s):

Gene Expression ◽

Regulatory Elements ◽

Regulatory Mechanisms ◽

Specific Gene ◽

Cell Type ◽

Specific Expression ◽

Risk Variants ◽

Allele Specific ◽

Cell Type Specific ◽

Regulatory Effects

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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