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result(s) for
"Oskolkov, Nikolay"
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Spatially and functionally distinct subclasses of breast cancer-associated fibroblasts revealed by single cell RNA sequencing
2018
Cancer-associated fibroblasts (CAFs) are a major constituent of the tumor microenvironment, although their origin and roles in shaping disease initiation, progression and treatment response remain unclear due to significant heterogeneity. Here, following a negative selection strategy combined with single-cell RNA sequencing of 768 transcriptomes of mesenchymal cells from a genetically engineered mouse model of breast cancer, we define three distinct subpopulations of CAFs. Validation at the transcriptional and protein level in several experimental models of cancer and human tumors reveal spatial separation of the CAF subclasses attributable to different origins, including the peri-vascular niche, the mammary fat pad and the transformed epithelium. Gene profiles for each CAF subtype correlate to distinctive functional programs and hold independent prognostic capability in clinical cohorts by association to metastatic disease. In conclusion, the improved resolution of the widely defined CAF population opens the possibility for biomarker-driven development of drugs for precision targeting of CAFs.
Cancer-associated fibroblasts (CAFs) are an important component of the breast tumour microenvironment. Here, single-cell RNA sequencing of CAFs from a mouse model of breast cancer defines three transcriptomically distinct subpopulations with putatively different functions.
Journal Article
Predicting type 2 diabetes via machine learning integration of multiple omics from human pancreatic islets
2024
Type 2 diabetes (T2D) is the fastest growing non-infectious disease worldwide. Impaired insulin secretion from pancreatic beta-cells is a hallmark of T2D, but the mechanisms behind this defect are insufficiently characterized. Integrating multiple layers of biomedical information, such as different Omics, may allow more accurate understanding of complex diseases such as T2D. Our aim was to explore and use Machine Learning to integrate multiple sources of biological/molecular information (multiOmics), in our case RNA-sequening, DNA methylation, SNP and phenotypic data from islet donors with T2D and non-diabetic controls. We exploited Machine Learning to perform multiOmics integration of DNA methylation, expression, SNPs, and phenotypes from pancreatic islets of 110 individuals, with ~ 30% being T2D cases. DNA methylation was analyzed using Infinium MethylationEPIC array, expression was analyzed using RNA-sequencing, and SNPs were analyzed using HumanOmniExpress arrays. Supervised linear multiOmics integration via DIABLO based on Partial Least Squares (PLS) achieved an accuracy of 91 ± 15% of T2D prediction with an area under the curve of 0.96 ± 0.08 on the test dataset after cross-validation. Biomarkers identified by this multiOmics integration, including
SACS
and
TXNIP
DNA methylation,
OPRD1
and
RHOT1
expression and a SNP annotated to
ANO1
, provide novel insights into the interplay between different biological mechanisms contributing to T2D. This Machine Learning approach of multiOmics cross-sectional data from human pancreatic islets achieved a promising accuracy of T2D prediction, which may potentially find broad applications in clinical diagnostics. In addition, it delivered novel candidate biomarkers for T2D and links between them across the different Omics.
Journal Article
Increased burden of ultra-rare structural variants localizing to boundaries of topologically associated domains in schizophrenia
by
Karlsson, Robert
,
Giusti-Rodriguez, Paola
,
Szatkiewicz, Jin P.
in
45/23
,
45/43
,
631/208/514/1948
2020
Despite considerable progress in schizophrenia genetics, most findings have been for large rare structural variants and common variants in well-imputed regions with few genes implicated from exome sequencing. Whole genome sequencing (WGS) can potentially provide a more complete enumeration of etiological genetic variation apart from the exome and regions of high linkage disequilibrium. We analyze high-coverage WGS data from 1162 Swedish schizophrenia cases and 936 ancestry-matched population controls. Our main objective is to evaluate the contribution to schizophrenia etiology from a variety of genetic variants accessible to WGS but not by previous technologies. Our results suggest that ultra-rare structural variants that affect the boundaries of topologically associated domains (TADs) increase risk for schizophrenia. Alterations in TAD boundaries may lead to dysregulation of gene expression. Future mechanistic studies will be needed to determine the precise functional effects of these variants on biology.
Common variants identified by large-scale genomewide association studies cannot account fully account for the heritability of schizophrenia (SCZ). Here, the authors report high-coverage whole-genome sequencing of 1162 SCZ cases and 936 controls and explore the contribution of different types of variants to SCZ.
Journal Article
aMeta: an accurate and memory-efficient ancient metagenomic profiling workflow
by
Vicente, Mário
,
Unneberg, Per
,
Bergfeldt, Nora
in
Ancient DNA
,
Ancient metagenomics
,
Animal Genetics and Genomics
2023
Analysis of microbial data from archaeological samples is a growing field with great potential for understanding ancient environments, lifestyles, and diseases. However, high error rates have been a challenge in ancient metagenomics, and the availability of computational frameworks that meet the demands of the field is limited. Here, we propose aMeta, an accurate metagenomic profiling workflow for ancient DNA designed to minimize the amount of false discoveries and computer memory requirements. Using simulated data, we benchmark aMeta against a current state-of-the-art workflow and demonstrate its superiority in microbial detection and authentication, as well as substantially lower usage of computer memory.
Journal Article
Genetic variant effects on gene expression in human pancreatic islets and their implications for T2D
2020
Most signals detected by genome-wide association studies map to non-coding sequence and their tissue-specific effects influence transcriptional regulation. However, key tissues and cell-types required for functional inference are absent from large-scale resources. Here we explore the relationship between genetic variants influencing predisposition to type 2 diabetes (T2D) and related glycemic traits, and human pancreatic islet transcription using data from 420 donors. We find: (a) 7741
cis
-eQTLs in islets with a replication rate across 44 GTEx tissues between 40% and 73%; (b) marked overlap between islet
cis-
eQTL signals and active regulatory sequences in islets, with reduced eQTL effect size observed in the stretch enhancers most strongly implicated in GWAS signal location; (c) enrichment of islet
cis-
eQTL signals with T2D risk variants identified in genome-wide association studies; and (d) colocalization between 47 islet
cis-
eQTLs and variants influencing T2D or glycemic traits, including
DGKB
and
TCF7L2
. Our findings illustrate the advantages of performing functional and regulatory studies in disease relevant tissues.
Mechanistic inference following GWAS is hampered by the lack of tissue-specific transcriptomic resources. Here the authors combine genetic variants predisposing to type 2 diabetes with human pancreatic islet RNA-seq data. They identify 7741 islet expression quantitative trait loci (eQTLs), providing a resource for functional interpretation of association signals mapping to non-coding sequence.
Journal Article
Unraveling the ancient fungal DNA from the Iceman gut
by
Götherström, Anders
,
Mimmo, Tanja
,
Oskolkov, Nikolay
in
Adaptability
,
Analysis
,
Ancient DNA (aDNA)
2024
Background
Fungal DNA is rarely reported in metagenomic studies of ancient samples. Although fungi are essential for their interactions with all kingdoms of life, limited information is available about ancient fungi. Here, we explore the possibility of the presence of ancient fungal species in the gut of Ötzi, the Iceman, a naturally mummified human found in the Tyrolean Alps (border between Italy and Austria).
Methods
A robust bioinformatic pipeline has been developed to detect and authenticate fungal ancient DNA (aDNA) from muscle, stomach, small intestine, and large intestine samples.
Results
We revealed the presence of ancient DNA associated with
Pseudogymnoascus
genus, with
P. destructans
and
P. verrucosus
as possible species, which were abundant in the stomach and small intestine and absent in the large intestine and muscle samples.
Conclusion
We suggest that Ötzi may have consumed these fungi accidentally, likely in association with other elements of his diet, and they persisted in his gut after his death due to their adaptability to harsh and cold environments. This suggests the potential co-occurrence of ancient humans with opportunistic fungal species and proposes and validates a conservative bioinformatic approach for detecting and authenticating fungal aDNA in historical metagenomic samples.
Journal Article
App-based COVID-19 syndromic surveillance and prediction of hospital admissions in COVID Symptom Study Sweden
by
Fitipaldi, Hugo
,
du Cadet, Julien Lavigne
,
Gomez, Maria F.
in
631/114/2397
,
692/308/174
,
692/699/255/2514
2022
The app-based COVID Symptom Study was launched in Sweden in April 2020 to contribute to real-time COVID-19 surveillance. We enrolled 143,531 study participants (≥18 years) who contributed 10.6 million daily symptom reports between April 29, 2020 and February 10, 2021. Here, we include data from 19,161 self-reported PCR tests to create a symptom-based model to estimate the individual probability of symptomatic COVID-19, with an AUC of 0.78 (95% CI 0.74–0.83) in an external dataset. These individual probabilities are employed to estimate daily regional COVID-19 prevalence, which are in turn used together with current hospital data to predict next week COVID-19 hospital admissions. We show that this hospital prediction model demonstrates a lower median absolute percentage error (MdAPE: 25.9%) across the five most populated regions in Sweden during the first pandemic wave than a model based on case notifications (MdAPE: 30.3%). During the second wave, the error rates are similar. When we apply the same model to an English dataset, not including local COVID-19 test data, we observe MdAPEs of 22.3% and 19.0% during the first and second pandemic waves, respectively, highlighting the transferability of the prediction model.
The app-based COVID Symptom Study was launched in Sweden in April 2020 to contribute to real-time COVID-19 surveillance using daily symptom reports from study participants. Here, the authors show how syndromic surveillance can be used to estimate regional COVID-19 prevalence and to predict later COVID-19 hospital admissions.
Journal Article
Genetic predisposition for beta cell fragility underlies type 1 and type 2 diabetes
2016
Adrian Liston and colleagues use a transgenic mouse model to demonstrate that beta cell failure is a mechanistic commonality in type 1 and type 2 diabetes. They find that the changes in the molecular pathways identified as contributing to beta cell loss are paralleled in human islets from patients with type 2 diabetes.
Type 1 (T1D) and type 2 (T2D) diabetes share pathophysiological characteristics, yet mechanistic links have remained elusive. T1D results from autoimmune destruction of pancreatic beta cells, whereas beta cell failure in T2D is delayed and progressive. Here we find a new genetic component of diabetes susceptibility in T1D non-obese diabetic (NOD) mice, identifying immune-independent beta cell fragility. Genetic variation in
Xrcc4
and
Glis3
alters the response of NOD beta cells to unfolded protein stress, enhancing the apoptotic and senescent fates. The same transcriptional relationships were observed in human islets, demonstrating the role of beta cell fragility in genetic predisposition to diabetes.
Journal Article
Epigenetic modulators link mitochondrial redox homeostasis to cardiac function in a sex-dependent manner
2024
While excessive production of reactive oxygen species (ROS) is a characteristic hallmark of numerous diseases, clinical approaches that ameliorate oxidative stress have been unsuccessful. Here, utilizing multi-omics, we demonstrate that in cardiomyocytes, mitochondrial isocitrate dehydrogenase (IDH2) constitutes a major antioxidative defense mechanism. Paradoxically reduced expression of IDH2 associated with ventricular eccentric hypertrophy is counterbalanced by an increase in the enzyme activity. We unveil redox-dependent sex dimorphism, and extensive mutual regulation of the antioxidative activities of IDH2 and NRF2 by a feedforward network that involves 2-oxoglutarate and L-2-hydroxyglutarate and mediated in part through unconventional hydroxy-methylation of cytosine residues present in introns. Consequently, conditional targeting of ROS in a murine model of heart failure improves cardiac function in sex- and phenotype-dependent manners. Together, these insights may explain why previous attempts to treat heart failure with antioxidants have been unsuccessful and open new approaches to personalizing and, thereby, improving such treatment.
Efforts to treat heart failure with antioxidants have failed. Here, authors reveal a robust sex-dependent endogenous defense against oxidative damage and demonstrate antioxidative treatment’s efficacy solely in subjects with inadequate redox capacity.
Journal Article