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27
result(s) for
"Petrova, Veronika"
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ASPEN: Robust detection of allelic dynamics in single cell RNA-seq
by
Petrova, Veronika
,
Vierbuchen, Thomas S.
,
Niu, Muqing
in
Alleles
,
Allelic Imbalance - genetics
,
Analysis
2025
Single-cell RNA-seq data from F1 hybrids provide a unique framework for dissecting complex regulatory mechanisms, but allelic measurements are limited by technical noise due to low counts. Here, we present ASPEN, a statistical method for modeling allelic mean and variance in single-cell transcriptomic data. ASPEN combines a sensitive mapping pipeline with a moderated beta-binomial model and adaptive shrinkage to distinguish allelic imbalance and changes to allelic variance in single cells. In both simulated and empirical datasets, ASPEN achieves a ~30% increase in sensitivity over existing approaches for single-cell allelic imbalance detection. Applied to mouse brain organoids and T cells, ASPEN identifies genes with incomplete X inactivation, random monoallelic expression, and significant deviations in allelic variance. These results reveal reduced variance in essential genes, consistent with tight regulatory control, and increased variance at neurodevelopmental and immune loci, indicative of regulatory flexibility.
Journal Article
Emergence of enhancers at late DNA replicating regions
2024
Enhancers are fast-evolving genomic sequences that control spatiotemporal gene expression patterns. By examining enhancer turnover across mammalian species and in multiple tissue types, we uncover a relationship between the emergence of enhancers and genome organization as a function of germline DNA replication time. While enhancers are most abundant in euchromatic regions, enhancers emerge almost twice as often in late compared to early germline replicating regions, independent of transposable elements. Using a deep learning sequence model, we demonstrate that new enhancers are enriched for mutations that alter transcription factor (TF) binding. Recently evolved enhancers appear to be mostly neutrally evolving and enriched in eQTLs. They also show more tissue specificity than conserved enhancers, and the TFs that bind to these elements, as inferred by binding sequences, also show increased tissue-specific gene expression. We find a similar relationship with DNA replication time in cancer, suggesting that these observations may be time-invariant principles of genome evolution. Our work underscores that genome organization has a profound impact in shaping mammalian gene regulation.
Here the authors report that enhancers appear more often in late-replicating DNA regions and are enriched for mutations affecting TF binding. This relationship with DNA replication time is seen in species evolution and cancer, suggesting a fundamental principle of genome evolution.
Journal Article
Towards resolution of the intron retention paradox in breast cancer
by
Visvader, Jane E.
,
Petrova, Veronika
,
Au, Amy Y. M.
in
Adipocytes
,
Alternative splicing
,
Biomedical and Life Sciences
2022
Background
After many years of neglect in the field of alternative splicing, the importance of intron retention (IR) in cancer has come into focus following landmark discoveries of aberrant IR patterns in cancer. Many solid and liquid tumours are associated with drastic increases in IR, and such patterns have been pursued as both biomarkers and therapeutic targets. Paradoxically, breast cancer (BrCa) is the only tumour type in which IR is reduced compared to adjacent normal breast tissue.
Methods
In this study, we have conducted a pan-cancer analysis of IR with emphasis on BrCa and its subtypes. We explored mechanisms that could cause aberrant and pathological IR and clarified why normal breast tissue has unusually high IR.
Results
Strikingly, we found that aberrantly decreasing IR in BrCa can be largely attributed to normal breast tissue having the highest occurrence of IR events compared to other healthy tissues. Our analyses suggest that low numbers of IR events in breast tumours are associated with poor prognosis, particularly in the luminal B subtype. Interestingly, we found that IR frequencies negatively correlate with cell proliferation in BrCa cells, i.e. rapidly dividing tumour cells have the lowest number of IR events. Aberrant RNA-binding protein expression and changes in tissue composition are among the causes of aberrantly decreasing IR in BrCa.
Conclusions
Our results suggest that IR should be considered for therapeutic manipulation in BrCa patients with aberrantly low IR levels and that further work is needed to understand the cause and impact of high IR in other tumour types.
Journal Article
Dynamic vibration absorber for shaft machining
by
Turbin, Igor
,
Varentsova, Tatyana
,
Petrova, Veronika
in
Absorbers
,
Automatic control
,
Circuit diagrams
2020
The article is concerned with a new method that minimizes the vibration level of non-rigid axisymmetric parts on lathes. A schematic diagram of the vibration absorber control path is given. Its configuration is changing due to fictitious elastic stiffness parameters, as well as damping and the part–support subsystem weight. A functional dual circuit diagram of an automatic vibration level control system for non-rigid shafts machining is presented and its working principle is described
Journal Article
Opioid analgesia for acute low back pain and neck pain (the OPAL trial): a randomised placebo-controlled trial
by
Day, Richard O
,
Mak, Wendy
,
Lin, Chung-Wei Christine
in
Acute Pain - drug therapy
,
Adolescent
,
Adult
2023
Opioid analgesics are commonly used for acute low back pain and neck pain, but supporting efficacy data are scarce. We aimed to investigate the efficacy and safety of a judicious short course of an opioid analgesic for acute low back pain and neck pain.
OPAL was a triple-blinded, placebo-controlled randomised trial that recruited adults (aged ≥18 years) presenting to one of 157 primary care or emergency department sites in Sydney, NSW, Australia, with 12 weeks or less of low back or neck pain (or both) of at least moderate pain severity. Participants were randomly assigned (1:1) using statistician-generated randomly permuted blocks to guideline-recommended care plus an opioid (oxycodone–naloxone, up to 20 mg oxycodone per day orally) or guideline-recommended care and an identical placebo, for up to 6 weeks. The primary outcome was pain severity at 6 weeks measured with the pain severity subscale of the Brief Pain Inventory (10-point scale), analysed in all eligible participants who provided at least one post-randomisation pain score, by use of a repeated measures linear mixed model. Safety was analysed in all randomly assigned eligible participants. The trial was registered with the Australian New Zealand Clinical Trials Registry (ACTRN12615000775516).
Between Feb 29, 2016, and March 10, 2022, 347 participants were recruited (174 to the opioid group and 173 to the placebo group). 170 (49%) of 346 participants were female and 176 (51%) were male. 33 (19%) of 174 participants in the opioid group and 25 (15%) of 172 in the placebo group had discontinued from the trial by week 6, due to loss to follow-up and participant withdrawals. 151 participants in the opioid group and 159 in the placebo group were included in the primary analysis. Mean pain score at 6 weeks was 2·78 (SE 0·20) in the opioid group versus 2·25 (0·19) in the placebo group (adjusted mean difference 0·53, 95% CI –0·00 to 1·07, p=0·051). 61 (35%) of 174 participants in the opioid group reported at least one adverse event versus 51 (30%) of 172 in the placebo group (p=0·30), but more people in the opioid group reported opioid-related adverse events (eg, 13 [7·5%] of 174 participants in the opioid group reported constipation vs six [3·5%] of 173 in the placebo group).
Opioids should not be recommended for acute non-specific low back pain or neck pain given that we found no significant difference in pain severity compared with placebo. This finding calls for a change in the frequent use of opioids for these conditions.
Australia's National Health and Medical Research Council, University of Sydney Faculty of Medicine and Health, and ReturnToWorkSA.
Journal Article
P-553: Ten years follow up of the precursors of early atherosclerosis in children
by
Rachneva, Rumiana D.
,
Petrova, Veronika S.
in
dislipidemias
,
early atherosclerosis
,
juvenile hypertension
2003
The frequency of the arterial hypertension and the lipid disturbances have been studied in 29 healthy children with family history of early coronary disease in a 10 year period. The evaluation in arterial hypertension (AH) has been carried out by a WHO methodology. In boys the frequency of AH is 56% and remains in the 10 years follow-up at 80%, while in girls it is 70% and falls to 30% in the follow-up. The hypercholesterolemia established in childhood continues into young age – 100% in cases of men and 80% in female. Increased levels of triglycerides in childhood are normalized later. The apoproteins and lipoprotein “a” levels are within the normal limits. Both genders have lower HDL-cholesterol (x=4,51 mmol/l) in the standard risk limits. The obtained results confirm the data of persistence of precursors of early atherosclerosis development from childhood to later age and the necessity of early prophylaxis.
Journal Article
Widespread Aberrant Alternative Splicing despite Molecular Remission in Chronic Myeloid Leukaemia Patients
2020
Vast transcriptomics and epigenomics changes are characteristic of human cancers, including leukaemia. At remission, we assume that these changes normalise so that omics-profiles resemble those of healthy individuals. However, an in-depth transcriptomic and epigenomic analysis of cancer remission has not been undertaken. A striking exemplar of targeted remission induction occurs in chronic myeloid leukaemia (CML) following tyrosine kinase inhibitor (TKI) therapy. Using RNA sequencing and whole-genome bisulfite sequencing, we profiled samples from chronic-phase CML patients at diagnosis and remission and compared these to healthy donors. Remarkably, our analyses revealed that abnormal splicing distinguishes remission samples from normal controls. This phenomenon is independent of the TKI drug used and in striking contrast to the normalisation of gene expression and DNA methylation patterns. Most remarkable are the high intron retention (IR) levels that even exceed those observed in the diagnosis samples. Increased IR affects cell cycle regulators at diagnosis and splicing regulators at remission. We show that aberrant splicing in CML is associated with reduced expression of specific splicing factors, histone modifications and reduced DNA methylation. Our results provide novel insights into the changing transcriptomic and epigenomic landscapes of CML patients during remission. The conceptually unanticipated observation of widespread aberrant alternative splicing after remission induction warrants further exploration. These results have broad implications for studying CML relapse and treating minimal residual disease.
Journal Article
ASPEN: Robust detection of allelic dynamics in single cell RNA-seq
2025
Single-cell RNA-seq data from F1 hybrids provides a unique framework for dissecting complex regulatory phenomena, but allelic measurements are limited by technical noise. Here, we present ASPEN, a statistical method for modeling allelic mean and variance in single-cell transcriptomic data from F1 hybrids. ASPEN uses a sensitive mapping pipeline and adaptive shrinkage to distinguish allelic imbalance and variance in single cells. Through extensive simulation based on sparse droplet-based single-cell data, ASPEN demonstrates improved sensitivity and control of false discoveries compared to existing approaches. Applied to mouse brain organoids and T cells, ASPEN identifies genes with incomplete X inactivation, stochastic monoallelic expression, and significant deviations in allelic variance. This reveals reduced variance in essential cellular pathways, and increased variance in neurodevelopmental and immune-specific genes.
Journal Article
Emergence of new enhancers at late DNA replicating regions
by
Cornejo-Paramo, Paola
,
Petrova, Veronika
,
Zhang, Xuan
in
Deep learning
,
Deoxyribonucleic acid
,
DNA biosynthesis
2024
Enhancers are fast-evolving genomic sequences that control spatiotemporal gene expression patterns. By examining enhancer turnover across mammalian species and in multiple tissue types, we uncovered a relationship between the emergence of novel enhancers and genome organization as a function of germline DNA replication time. While enhancers are most abundant in euchromatic regions, new enhancers emerged almost twice as often in late compared to early germline replicating regions, independent of transposable elements. Using a sequence model, we demonstrate that new enhancers are enriched for mutations that alter transcription factor (TF) binding. Recently evolved enhancers appeared to be mostly neutrally evolving and enriched in eQTLs. They also show more tissue specificity than conserved enhancers, and the TFs that bind to these elements, as inferred by binding sequences, also show increased tissue-specific gene expression. We find a similar relationship with DNA replication time in cancer, suggesting that these observations may be time-invariant principles of genome evolution. Our work underscores that genome organization has a profound impact in shaping mammalian gene regulation.Competing Interest StatementThe authors have declared no competing interest.Footnotes* Revised text for clarity and additional analyses added