Biology subjects

D'Antonio-Chronowska, A.

Publications and source records attributed to D'Antonio-Chronowska, A..

At least 19 recordsLinked to original sources

bioRxiv2025

Single cell and spatial characterization of the human pancreas reveals drivers of beta cell dysfunction in cystic fibrosis

Cystic fibrosis (CF) causes severely damaged pancreas morphology and results in high rates of cystic fibrosis-related diabetes (CFRD), but the cellular pathways and regulatory programs driving CFRD pathogenesis in the pancreas are not understood. In this study, we performed single cell multiomic and spatial profiling of 2.04M cells in the pancreas from 23 non-disease and CF donors and defined regulatory programs and tissue niches of specific cell types and sub-types in CF. A high-mucin sub-type of ductal cells had relatively preserved abundance, altered localization and up-regulated stress, secretion and pro-fibrotic activity in CF, and conventional ductal cells showed evidence for transition to the high-mucin state. Increased inflammatory and fibrotic pathway activity in CF was linked to closer proximity and crosstalk between immune and stellate cells in specific niches. Beta cells had extensive genomic changes in CF, including increased stress and insulin secretion-related processes, and these changes were broadly distinct from those in type 1 and type 2 diabetes. Islets in CF preferentially localized near large adipose tissue and collagen structures, and both areas were strongly linked to beta cell loss in CF due to signaling from adipocytes, macrophages, stellate, and high-mucin ductal cells. Overall, our results reveal cellular drivers of pancreatic dysfunction in CF and offer new in-roads to preserving beta cells in CFRD.

genomics↗

bioRxiv2025

Genetics of growth rate in induced pluripotent stem cells

Human induced pluripotent stem cells (iPSCs) have transformed biomedical research by enabling the generation of diverse cell types from accessible somatic tissues. However, certain fundamental biological properties, such as the genetic and epigenetic determinants of iPSC proliferation, remain poorly characterized. We measured the growth of iPSC lines derived from 602 unique donors using high-throughput time-lapse imaging, quantified proliferation through a growth Area-Under-the-Curve (gAUC) phenotype, and correlated gAUC with the gene expression and genotype of the cell lines. We identified 3,091 genes associated with gAUC, many of which are well established regulators of cell proliferation. We also found that rare deleterious variants in WDR54 were associated with reduced iPSC growth and that WDR54 was differentially expressed with respect to gAUC. Although no common variants showed a genome-wide association with gAUC, iPSC lines from monozygotic twins were highly correlated, and common genetic variation explained approximately 71-75% of the variance in iPSC growth rates. These results indicate a complex genetic architecture of iPSC growth rates, where rare, large-effect variants in important growth regulators, including WDR54, are layered onto a highly polygenic background. These findings have important implications for the design of pooled iPSC-based studies and disease models, which may be confounded by intrinsic growth differences.

developmental biology↗

bioRxiv2024

Recruitment of CTCF to the SIRT1 promoter after Oxidative Stress mediates Cardioprotective Transcription

Because most DNA-binding transcription factors (dbTFs), including the architectural regulator CTCF, bind RNA and exhibit di-/multimerization, a central conundrum is whether these distinct properties are regulated post-transcriptionally to modulate transcriptional programs. Here, investigating stress-dependent activation of SIRT1, encoding an evolutionarily-conserved protein deacetylase, we show that induced phosphorylation of CTCF acts as a rheostat to permit CTCF occupancy of low-affinity promoter DNA sites to precisely the levels necessary. This CTCF recruitment to the SIRT1 promoter is eliciting a cardioprotective cardiomyocyte transcriptional activation program and provides resilience against the stress of the beating heart in vivo. Mice harboring a mutation in the conserved low-affinity CTCF promoter binding site exhibit an altered, cardiomyocyte-specific transcriptional program and a systolic heart failure phenotype. This transcriptional role for CTCF reveals that a covalent dbTF modification regulating signal-dependent transcription serves as a previously unsuspected component of the oxidative stress response.

cell biology↗

bioRxiv2024

IFN-γ activates an immune-like regulatory network in the cardiac vascular endothelium

The regulatory mechanisms underlying the response to pro-inflammatory cytokines in cardiac diseases are poorly understood. Here, we use iPSC-derived cardiovascular progenitor cells (CVPCs) to model the response to interferon gamma (IFN{gamma}) in human cardiac tissue. We generate RNA-seq and ATAC-seq for four CVPCs that were treated with IFN{gamma} and compare them with paired untreated controls. Transcriptional differences after treatment show that IFN{gamma} initiates an innate immune cell-like response, shifts the CVPC transcriptome towards coronary artery and aorta profiles, and stimulates expression of endothelial cell-specific genes. Analysis of the accessible chromatin shows that IFN{gamma} is a potent chromatin remodeler and establishes an IRF-STAT immune-cell like regulatory network. Finally, we show that 11 GWAS risk variants for 8 common cardiac diseases overlap IFN{gamma}-upregulated ATAC-seq peaks. Our findings reveal insights into IFN{gamma}-induced activation of an immune-like regulatory network in the cardiac vascular endothelium and the potential role that regulatory elements in this pathway play in common cardiac diseases. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=103 SRC="FIGDIR/small/592380v2_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@e66966org.highwire.dtl.DTLVardef@111da44org.highwire.dtl.DTLVardef@110a8f5org.highwire.dtl.DTLVardef@c4997b_HPS_FORMAT_FIGEXP M_FIG C_FIG Paired RNA-seq and ATAC-seq was generated for induced pluripotent stem cell derived cardiovascular progenitor cells (CVPCs) treated with interferon-gamma (IFN{gamma}) and matched controls to model the effect of the pro-inflammatory cytokine on human cardiac tissue. Using the RNA-seq, transcriptomic changes were characterized by performing differential gene expression analysis, integrating gene expression data from hundreds of samples of adult cardiac tissues, and using single cell RNA-seq to evaluate cell type-specificity. Using the ATAC-seq, epigenomic changes were characterized by performing differential chromatin accessibility and transcription factor binding analyses, and annotating ATAC-seq peaks with chromatin states from over 800 tissues. Genetic variants in risk loci associated with cardiac diseases were intersected with ATAC-seq peaks to evaluate whether they were in chromatin that is only accessible after IFN{gamma} treatment. The findings demonstrate the utility of using CVPCs to model the effects of cytokines on cardiac tissues and provide the framework for conducting large scale studies to further evaluate GWAS loci that are explained by context-specific regulatory variation.

bioinformatics↗

bioRxiv2024

Multi-omic QTL mapping in early developmental tissues reveals phenotypic and temporal complexity of regulatory variants underlying GWAS loci

Most GWAS loci are presumed to affect gene regulation, however, only [~]43% colocalize with expression quantitative trait loci (eQTLs). To address this colocalization gap, we identify eQTLs, chromatin accessibility QTLs (caQTLs), and histone acetylation QTLs (haQTLs) using molecular samples from three early developmental (EDev) tissues. Through colocalization, we annotate 586 GWAS loci for 17 traits by QTL complexity, QTL phenotype, and QTL temporal specificity. We show that GWAS loci are highly enriched for colocalization with complex QTL modules that affect multiple elements (genes and/or peaks). We also demonstrate that caQTLs and haQTLs capture regulatory variations not associated with eQTLs and explain [~]49% of the functionally annotated GWAS loci. Additionally, we show that EDev-unique QTLs are strongly depleted for colocalizing with GWAS loci. By conducting one of the largest multi-omic QTL studies to date, we demonstrate that many GWAS loci exhibit phenotypic complexity and therefore, are missed by traditional eQTL analyses.

genomics↗

bioRxiv2023

Unsupervised Machine Learning Identifies Chromatin Accessibility Regulatory Networks that Define Cell State Transitions in Pluripotency

Stem cells exist in vitro in a spectrum of interconvertible pluripotent states. Analyzing hundreds of hiPSCs derived from different individuals, we show the proportions of these pluripotent states vary considerably across lines. We discovered 13 gene network modules (GNMs) and 13 regulatory network modules (RNMs), which were highly correlated with each other suggesting that the coordinated co-accessibility of regulatory elements in the RNMs likely underlied the coordinated expression of genes in the GNMs. Epigenetic analyses revealed that regulatory networks underlying self-renewal and pluripotency have a surprising level of complexity. Genetic analyses identified thousands of regulatory variants that overlapped predicted transcription factor binding sites and were associated with chromatin accessibility in the hiPSCs. We show that the master regulator of pluripotency, the NANOG-OCT4 Complex, and its associated network were significantly enriched for regulatory variants with large effects, suggesting that they may play a role in the varying cellular proportions of pluripotency states between hiPSCs. Our work captures the coordinated activity of tens of thousands of regulatory elements in hiPSCs and bins these elements into discrete functionally characterized regulatory networks, shows that regulatory elements in pluripotency networks harbor variants with large effects, and provides a rich resource for future pluripotent stem cell research.

genomics↗

bioRxiv2022

Affinity-optimizing variants within cardiac enhancers disrupt heart development and contribute to cardiac traits

Enhancers direct precise gene expression patterns during development and harbor the majority of variants associated with disease. We find that suboptimal affinity ETS transcription factor binding sites are prevalent within Ciona and human developmental heart enhancers. Here we demonstrate in two diverse systems, Ciona intestinalis and human iPSC-derived cardiomyocytes (iPSC-CMs), that single nucleotide changes can optimize the affinity of ETS binding sites, leading to gain-of-function gene expression associated with heart phenotypes. In Ciona, ETS affinity-optimizing SNVs lead to ectopic expression and phenotypic changes including two beating hearts. In human iPSC-CMs, an affinity-optimizing SNV associated with QRS duration occurs within an SCN5A enhancer and leads to increased enhancer activity. Our mechanistic approach provides a much-needed systematic framework that works across different enhancers, cell types and species to pinpoint causal enhancer variants contributing to enhanceropathies, phenotypic diversity and evolutionary changes. In BriefThe prevalent use of low-affinity ETS sites within developmental heart enhancers creates vulnerability within genomes whereby single nucleotide changes can dramatically increase binding affinity, causing gain-of-function enhancer activity that impacts heart development. HighlightsETS affinity-optimizing SNVs can lead to migration defects and a multi-chambered heart. An ETS affinity-optimizing human SNV within an SCN5A enhancer increases expression and is associated with QRS duration. Searching for ETS affinity-optimizing variants is a systematic and generalizable approach to pinpoint causal enhancer variants.

genomics↗

bioRxiv2021

Regulatory variants active in iPSC-derived pancreatic progenitor cells are associated with Type 2 Diabetes in adults

Pancreatic progenitor cells (PPC) are an early developmental multipotent cell type that give rise to mature endocrine, exocrine, and ductal cells. To investigate the extent to which regulatory variants active in PPC contribute to pancreatic complex traits and disease in the adult, we derived PPC from induced pluripotent stem cells (iPSCs) of nine unrelated individuals and generated single cell profiles of chromatin accessibility (snATAC- seq) and transcriptome (scRNA-seq). While iPSC-PPC differentiation was asynchronous and included cell types from early to late developmental stages, we found that the predominant cell type consisted of NKX6-1+ progenitors. Genetic characterization using snATAC-seq identified 86,261 regulatory variants that either displayed chromatin allelic bias and/or were predicted to affect active transcription factor (TF) binding sites. Integration of these regulatory variants with 380 fine-mapped type 2 diabetes (T2D) risk loci identified regulatory variants in 209 of these loci that are functional in iPSC-PPC, either by affecting transcription factor binding or through association with allelic effects on chromatin accessibility. The PPC active regulatory variants in 65 of these loci showed strong evidence of causally underlying the association with T2D. Our study shows that studying the functional associations of regulatory variation in iPSC-PPC enables the identification and characterization of causal SNPs for adult Type 2 Diabetes.

genetics↗

bioRxiv2021

Fine mapping spatiotemporal mechanisms of genetic variants underlying cardiac traits and disease

The causal variants and genes underlying thousands of cardiac GWAS signals have yet to be identified. Here, we leveraged spatiotemporal information on 966 RNA-seq cardiac samples and performed an expression quantitative trait locus (eQTL) analysis detecting eQTLs considering both eGenes and eIsoforms. We identified 2,578 eQTLs associated with a specific developmental stage-, tissue- and/or cell type. Colocalization between eQTL and GWAS signals of five cardiac traits identified variants with high posterior probabilities for being causal in 210 GWAS loci. Pulse pressure GWAS loci were enriched for colocalization with fetal- and smooth muscle- eQTLs; pulse rate with adult- and cardiac muscle- eQTLs; and atrial fibrillation with cardiac muscle- eQTLs. Fine mapping identified 79 credible sets with five or fewer SNPs, of which 15 were associated with spatiotemporal eQTLs. Our study shows that many cardiac GWAS variants impact traits and disease in a developmental stage-, tissue- and/or cell type-specific fashion.

genetics↗

bioRxiv2021

iPSC-derived pancreatic progenitors are an optimal model system to study T2D regulatory variants active during fetal development of the pancreas

The impact of genetic regulatory variation active in early pancreatic development on adult pancreatic disease and traits is not well understood. Here, we generate a panel of 107 fetal-like iPSC-derived pancreatic progenitor cells (iPSC-PPCs) from whole genome-sequenced individuals and identify 4,065 genes and 4,016 isoforms whose expression and/or alternative splicing are affected by regulatory variation. We integrate eQTLs identified in adult islets and whole pancreas samples, which reveal 1,805 eQTL associations that are unique to the fetal-like iPSC-PPCs and 1,043 eQTLs that exhibit regulatory plasticity across the fetal-like and adult pancreas tissues. Colocalization with GWAS risk loci for pancreatic diseases and traits show that some putative causal regulatory variants are active only in the fetal-like iPSC-PPCs and likely influence disease by modulating expression of disease-associated genes in early development, while others with regulatory plasticity likely exert their effects in both the fetal and adult pancreas by modulating expression of different disease genes in the two developmental stages.

genomics↗

bioRxiv2019

Structural variant classes and short tandem repeats differentially impact gene expression and complex traits

Structural variants (SVs) and short tandem repeats (STRs) comprise a broad group of diverse DNA variants which vastly differ in their sizes and distributions across the genome. Here, we show that different SV classes and STRs differentially impact gene expression and complex traits. Functional differences between SV classes and STRs include their genomic locations relative to eGenes, likelihood of being associated with multiple eGenes, associated eGene types (e.g., coding, noncoding, level of evolutionary constraint), effect sizes, linkage disequilibrium with tagging single nucleotide variants used in GWAS, and likelihood of being associated with GWAS traits. We also identified a set of high-impact SVs/STRs associated with the expression of three or more eGenes via chromatin loops and showed they are highly enriched for being associated with GWAS traits. Our study provides insights into the genomic properties of structural variant classes and short tandem repeats that impact gene expression and human traits.

genomics↗

bioRxiv2019

Discovery and Quality Analysis of a Comprehensive Set of Structural Variants and Short Tandem Repeats using Deep Whole Genome Sequencing Data

Structural variants (SVs) and short tandem repeats (STRs) are important sources of genetic diversity but are not routinely analyzed in genetic studies because they are difficult to accurately identify and genotype. Because SVs and STRs range in size and type, it is necessary to apply multiple algorithms that incorporate different types of evidence from sequencing data and employ complex filtering strategies to discover a comprehensive set of high-quality and reproducible variants. Here we assembled a set of 719 deep whole genome sequencing (WGS) samples (mean 42x) from 477 distinct individuals which we used to discover and genotype a wide spectrum of SV and STR variants using five algorithms. We used 177 unique pairs of genetic replicates to identify factors that affect variant call reproducibility and developed a systematic filtering strategy to create of one of the most complete and well characterized maps of SVs and STRs to date.

genomics↗

bioRxiv2019

Cellular deconvolution of GTEx tissues powers eQTL studies to discover thousands of novel disease and cell-type associated regulatory variants

The Genotype-Tissue Expression (GTEx) resource has contributed a wealth of novel insights into the regulatory impact of genetic variation on gene expression across human tissues, however thus far has not been utilized to study how variation acts at the resolution of the different cell types composing the tissues. To address this gap, using liver and skin as a proof-of-concept tissues, we show that readily available signature genes based on expression profiles of mouse cell types can be used to deconvolute the cellular composition of human GTEx tissues. We then deconvoluted 6,829 bulk RNA-seq samples corresponding to 28 GTEx tissues and show that we are able to quantify cellular heterogeneity, determining both the different cell types present in each of the tissues and how their proportions vary between samples of the same tissue type. Conducting eQTL analyses for GTEx liver and skin samples using cell type composition estimates as interaction terms, we identified thousands of novel genetic associations that had lower effect sizes and were cell-type-associated. We further show that cell-type-associated eQTLs in skin colocalize with melanoma, malignant neoplasm, and infection signatures, indicating variants that influence gene expression in distinct skin cell types play important roles in skin traits and disease. Overall, our study provides a framework to estimate the relative fractions of different cell types in GTEx tissues using signature genes from mouse cell types and functionally characterize human genetic variation that impacts gene expression in a cell-type-specific manner.

genetics↗

bioRxiv2019

Human iPSC gene signatures and X chromosome dosage impact response to WNT inhibition and cardiac differentiation fate

Non-genetic variability in human induced pluripotent stem cell (iPSC) lines impacts their differentiation outcome, limiting their utility for genetic studies and clinical applications. Despite the importance of understanding how non-genetic molecular variability influences iPSC differentiation outcome, large-scale studies capable of addressing this question have not yet been conducted. Here, we performed 258 directed differentiations of 191 iPSC lines using established protocols to generate iPSC-derived cardiovascular progenitor cells (iPSC-CVPCs). We observed cellular heterogeneity across the iPSC-CVPC samples due to varying fractions of two cell types: cardiomyocytes (CMs) and epicardium-derived cells (EPDCs). Analyzing the transcriptomes of CM-fated and EPDC-fated iPSCs discovered that 91 signature genes and X chromosome dosage differences influence WNT inhibition response during differentiation and are associated with cardiac fate. Analysis of an independent set of 39 iPSCs differentiated to the cardiac lineage confirmed shared sex and transcriptional differences that impact cardiac fate outcome. The scale and systematic approach of our study enabled novel insights into how iPSC transcriptional and X chromosome gene dosage differences influence WNT signaling during differentiation and hence cardiac cell fate.

genomics↗

bioRxiv2019

Chromatin co-accessibility is highly structured, spans entire chromosomes, and mediates long range regulatory genetic effects

Chromatin accessibility identifies active regions of the genome, often at transcription factor (TF) binding sites, enhancers, and promoters, and contains regulatory genetic variation. Functionally related accessible sites have been reported to be co-accessible; however, the prevalence and range of co-accessibility is unknown. We perform ATAC-seq in induced pluripotent stem cells from 134 individuals and integrate it with RNA-seq, WGS, and ChIP-seq, providing the first long-range chromosome-length analysis of co-accessibility. We show that co-accessibility is highly connected, with sites having a median of 24 co-accessible partners up to 250Mb away. We also show that co-accessibility can de novo identify known and novel co-expressed genes, and co-regulatory TFs and chromatin states. We perform a cis and trans-caQTL, a trans-eQTL, and examine allelic effects of co-accessibility, identifying tens of thousands of trans-caQTLs, and showing that trans genetic effects can be propagated through co-accessibility to gene expression for cell-type and disease relevant genes.

genomics↗

bioRxiv2019

In-depth genetic analysis of 6p21.3 reveals insights into associations between HLA types and complex traits and disease

The highly polymorphic major histocompatibility (MHC) region encodes the human leucocyte antigen (HLA) gene complex and is associated with many autoimmune and infectious diseases. Despite the importance of this interval, comprehensive genetic studies interrogating associations between HLA types, expression of non-HLA genes and disease, have not yet been conducted. To address this issue, we collected high-coverage whole genome sequence from 419 individuals and performed HLA typing at the highest resolution. Using RNA-seq from matched iPSC lines, we conducted an in-depth eQTL analysis using "personalized" transcripts, which significantly improved estimated expression levels of HLA genes, and showed HLA types have genetic associations independent from SNPs. We leveraged the eQTL results to examine associations between expression levels of non-HLA genes and disease. As a proof-of-principle, we investigated RNF5, whose protein product is a novel drug target in cystic fibrosis. We observed that decreased expression of RNF5 was associated with the 8.1 ancestral haplotype, which was previously found associated with protection against infection in cystic fibrosis. Overall, our study shows that genetically dissecting the MHC region provides novel insights into mechanisms underlying associations of this interval with disease.

genomics↗

bioRxiv2018

Human iPSC-derived retinal pigment epithelium: a model system for identifying and functionally characterizing causal variants at AMD risk loci

We evaluate whether human induced pluripotent stem cell-derived retinal pigment epithelium (iPSC-RPE) cells can be used to prioritize and functionally characterize causal variants at age-related macular degeneration (AMD) risk loci. We generated iPSC-RPE from six subjects and show that they have morphological and molecular characteristics similar to native RPE. We generated RNA-seq, ATAC-seq, and H3K27ac ChIP-seq data and observe high similarity in gene expression and enriched transcription factor motif profiles between iPSC-RPE and human fetal-RPE. We performed fine-mapping of AMD risk loci by integrating molecular data from the iPSC-RPE, adult retina, and adult RPE, which identified rs943080 as the probable causal variant at VEGFA. We show that rs943080 is associated with altered chromatin accessibility of a distal ATAC-seq peak, decreased overall gene expression of VEGFA, and allele specific expression of a non-coding transcript. These results provide insight into the mechanism underlying the association of the VEGFA locus with AMD.

genetics↗

bioRxiv2018

Allele-specific NKX2-5 binding underlies multiple genetic associations with human EKG traits

Genetic variation affecting the binding of transcription factors (TFs) has been proposed as a major mechanism underlying susceptibility to common disease. NKX2-5, a key cardiac development TF, has been associated with electrocardiographic (EKG) traits through GWAS, but the extent to which differential binding of NKX2-5 contributes to these traits has not yet been studied. Here, we analyzed transcriptomic and epigenomic data generated from iPSC-derived cardiomyocyte lines (iPSC-CMs) from seven whole-genome sequenced individuals in a three-generational family. We identified ~2,000 single nucleotide variants (SNVs) associated with allele-specific effects (ASE) on NKX2-5 binding. These ASE-SNVs were enriched for altered TF motifs (both cognate and other cardiac TFs), and were positively correlated with changes in H3K27ac in iPSC-CMs, suggesting they impact cardiac enhancer activity. We found that NKX2-ASE-SNVs were significantly enriched for being heart-specific eQTLs and EKG GWAS variants, suggesting that altered NKX2-5 binding at multiple sites across the genome influences EKG traits. We used a fine-mapping approach to integrate iPSC-CM molecular phenotype data with a GWAS for heart rate, and determined that NKX2-5 ASE variants are likely causal for numerous known, as well as previously unidentified, heart rate loci. Analyzing Hi-C and gene expression data from iPSC-CMs at these heart rate loci, we identified several genes likely to be causally involved in heart rate variability. Our study demonstrates that differential binding of NKX2-5 is a common mechanism underlying genetic association with EKG traits, and shows that characterizing variants associated with differential binding of development TFs in iPSC-derived cell lines can identify novel loci and mechanisms influencing complex traits.

genetics↗