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98 Publications visible to you, out of a total of 98
Telomere Maintenance Pathways in Lower-Grade Gliomas: Insights from Genetic Subtypes and Telomere Length Dynamics

Abstract (Expand)

Telomere maintenance mechanisms (TMMs) play a critical role in cancer biology, particularly in lower-grade gliomas (LGGs), where telomere dynamics and pathway activity remain poorly understood. In this … study, we analyzed TCGA-LGG and CGGA datasets, focusing on telomere length variations, pathway activity, and survival data across IDH subtypes. Additional validation was performed using the GEO COPD and GBM datasets, ensuring consistency in data processing and batch effect correction. Our analysis revealed significant differences in TEL pathway activation between Short- and Long-TL groups, emphasizing the central role of TERT in telomere maintenance. In contrast, ALT pathway activation displayed subtype-specific patterns, with IDH-wt tumors exhibiting the highest ALT activity, primarily driven by the RAD51 branch. Validation using CGGA data confirmed these findings, demonstrating consistent TEL and ALT pathway behaviors across datasets. Additionally, genetic subtype analysis revealed substantial telomere length variability associated with ATRX and IDH mutation status. Notably, IDHwt-ATRX WT tumors exhibited the shortest telomere length and the highest ALT pathway activity. These findings highlight distinct telomere regulatory dynamics across genetic subtypes of LGG and provide new insights into potential therapeutic strategies targeting telomere maintenance pathways.

Authors: Meline Hakobyan, Hans Binder, Arsen Arakelyan

Date Published: 28th Apr 2025

Publication Type: Journal

Transcriptome alterations in long-term mining region residents: Insights into immune response and molecular pathways.

Abstract (Expand)

Pollution with metals and metalloids is a global problem that adversely affects human health and environment. Although several studies have reported gene expression changes in response to human exposures … to metals, there are a limited number of studies exploring the effect of long-term residence in mining areas. The evidence of increased levels of several essential and non-essential metals in soil, water, and plants in Kapan mining area (Armenia) has been previously demonstrated in several environmental studies. Our study investigated the impact of long-term residence in this mining area on the transcriptome state of human peripheral blood mononuclear cells and the possible association of transcriptome changes with the blood metallome. In total, 58 participants including 27 mining region residents (MRR) and 31 non-mining region residents (NMR) were selected for our study. Transcriptomic analysis of peripheral blood mononuclear cells was performed by mRNA sequencing. Differential expression analyses were conducted using generalized linear modeling, optimized for participant demographics, cell types, and sequencing technical factors, followed by pathway analysis. The study revealed that long-term residence in a mining area is correlated with alterations in the blood transcriptome, with responses varying by sex. The identified transcriptome changes were enriched for pathways related to immune response and RNA translation. These changes correlated with higher blood levels of a mixture of non-essential metals, including arsenic, antimony, nickel, thallium, and beryllium. Additionally, the study identified differences in the transcriptome response between male and female MRR. While females exhibited a stronger immune response, males show dysregulation in ion transport and epigenetic modifications. Our findings contribute to understanding the effects of long-term residence in mining regions and can aid in developing more effective risk assessment and mitigation approaches in target populations.

Authors: A. Stepanyan, A. Arakelyan, J. Schug

Date Published: 24th Mar 2025

Publication Type: Journal

Assigning Transcriptomic Subtypes to Chronic Lymphocytic Leukemia Samples Using Nanopore RNA-Sequencing and Self-Organizing Maps.

Abstract (Expand)

Background/Objectives: Massively parallel sequencing technologies have advanced chronic lymphocytic leukemia (CLL) diagnostics and precision oncology. Illumina platforms, while offering robust performance, … require substantial infrastructure investment and a large number of samples for cost-efficiency. Conversely, third-generation long-read nanopore sequencing from Oxford Nanopore Technologies (ONT) can significantly reduce sequencing costs, making it a valuable tool in resource-limited settings. However, nanopore sequencing faces challenges with lower accuracy and throughput than Illumina platforms, necessitating additional computational strategies. In this paper, we demonstrate that integrating publicly available short-read data with in-house generated ONT data, along with the application of machine learning approaches, enables the characterization of the CLL transcriptome landscape, the identification of clinically relevant molecular subtypes, and the assignment of these subtypes to nanopore-sequenced samples. Methods: Public Illumina RNA sequencing data for 608 CLL samples were obtained from the CLL-Map Portal. CLL transcriptome analysis, gene module identification, and transcriptomic subtype classification were performed using the oposSOM R package for high-dimensional data visualization with self-organizing maps. Eight CLL patients were recruited from the Hematology Center After Prof. R. Yeolyan (Yerevan, Armenia). Sequencing libraries were prepared from blood total RNA using the PCR-cDNA sequencing-barcoding kit (SQK-PCB109) following the manufacturer's protocol and sequenced on an R9.4.1 flow cell for 24-48 h. Raw reads were converted to TPM values. These data were projected into the SOMs space using the supervised SOMs portrayal (supSOM) approach to predict the SOMs portrait of new samples using support vector machine regression. Results: The CLL transcriptomic landscape reveals disruptions in gene modules (spots) associated with T cell cytotoxicity, B and T cell activation, inflammation, cell cycle, DNA repair, proliferation, and splicing. A specific gene module contained genes associated with poor prognosis in CLL. Accordingly, CLL samples were classified into T-cell cytotoxic, immune, proliferative, splicing, and three mixed types: proliferative-immune, proliferative-splicing, and proliferative-immune-splicing. These transcriptomic subtypes were associated with survival orthogonal to gender and mutation status. Using supervised machine learning approaches, transcriptomic subtypes were assigned to patient samples sequenced with nanopore sequencing. Conclusions: This study demonstrates that the CLL transcriptome landscape can be parsed into functional modules, revealing distinct molecular subtypes based on proliferative and immune activity, with important implications for prognosis and treatment that are orthogonal to other molecular classifications. Additionally, the integration of nanopore sequencing with public datasets and machine learning offers a cost-effective approach to molecular subtyping and prognostic prediction, facilitating more accessible and personalized CLL care.

Authors: A. Arakelyan, T. Sirunyan, G. Khachatryan, S. Hakobyan, A. Minasyan, M. Nikoghosyan, M. Hakobyan, A. Chavushyan, G. Martirosyan, Y. Hakobyan, H. Binder

Date Published: 13th Mar 2025

Publication Type: Journal

Long-lasting sex-specific alteration in left ventricular cardiac transcriptome following gamma and simGCRsim radiation

Abstract (Expand)

Space irradiation (IR) is an important health risk for deep-space missions. We reported heart failure with preserved ejection fraction like cardiac phenotype 660-days following exposure to a single-dose … of a simplified galactic cosmic ray simulation (simGCRsim) only in males with functional and structural impairment in left ventricular (LV) function. This sex-based dichotomy prompted us to investigate sex-specific changes in the LV transcriptome in three-month-old male and female mice exposed to 137Cs-γ- or simGCRsim-IR. Non-IR male and female (10 each) mice served as controls. LVs were collected at 440/660- and 440/550-days post-IR, male and female, respectively. RNA sequencing, differential gene expression, and functional annotation were performed on tissues from 5 mice/group. Sex and post-IR time points had the greatest influence on gene expression, surpassing the IR-type effects. SimGCRsim-IR showed more persistent transcriptome changes than γ-IR. We suggest that the single IR effects can persist up to 550-660 days, with overwhelmingly sex-biased responses at individual gene expression level.

Authors: Roksana Zakharyan, Siras Hakobyan, Agnieszka Brojakowska, Suren Davitavyan, Ani Stepanyan, Tamara Sirunyan, Gisane Khachatryan, Mary K. Khlgatian, Malik Bisserier, Shihong Zhang, Susmita Sahoo, Lahouaria Hadri, Venkata Naga Srikanth Garikipati, Arsen Arakelyan, David A. Goukassian

Date Published: 18th Feb 2025

Publication Type: Journal

Molecular Epidemiology and In-Depth Characterization of Klebsiella pneumoniae Clinical Isolates from Armenia

Abstract (Expand)

The global dissemination of Klebsiella pneumoniae pathotypes with multidrug-resistant (MDR) and hypervirulent traits poses a threat to public health. The situation in Armenia is unclear, and we performed … a comprehensive characterisation of 48 clinical isolates of K. pneumoniae, collected from 2018 to 2024. The majority of the isolates (64.58%) were extensively drug-resistant (XDR) and MDR. Genomic analysis of 21 isolates revealed the presence of international high-risk MDR clones (ST395, ST15, and ST307). The ST395 strains were isolated from children and resisted the first-line drugs such as beta-lactams. These isolates harboured a range of virulence determinants, from capsule polysaccharides to siderophores to regulators of the mucoid phenotype. The ST395 strains are enriched by ICEs, plasmids, and prophages, on which antimicrobial resistance (AMR) and virulence genes are located and which may lead to the convergence of MDR and hypervirulent traits. There is a widespread non-specific AMR mechanism among our K. pneumoniae strains. These are mutations in the porin genes, which reduce permeability to antimicrobials, and mutations in the regulators of efflux pumps, which lead to overexpression of drug efflux pumps such as AcrAB. These mechanisms may contribute to the elevated MICs and confer AMR to strains with no specific AMR genes.

Authors: Anahit Sedrakyan, Zaruhi Gevorgyan, Magdalina Zakharyan, Karine Arakelova, Shoghik Hakobyan, Alvard Hovhannisyan, Rustam Aminov

Date Published: 9th Jan 2025

Publication Type: Journal

Evaluating sex-specific responses to western diet across the lifespan: impact on cardiac function and transcriptomic signatures in C57BL/6J mice at 530 and 640/750 days of age.

Abstract (Expand)

BACKGROUND: Long-term consumption of Western Diet (WD) is a well-established risk factor for the development of cardiovascular disease (CVD); however, there is a paucity of studies on the long-term … effects of WD on the pathophysiology of CVD and sex-specific responses. METHODS: Our study aimed to investigate the sex-specific pathophysiological changes in left ventricular (LV) function using transthoracic echocardiography (ECHO) and LV tissue transcriptomics in WD-fed C57BL/6 J mice for 125 days, starting at the age of 300 through 425 days. RESULTS: In female mice, consumption of the WD diet showed long-term effects on LV structure and possible development of HFpEF-like phenotype with compensatory cardiac structural changes later in life. In male mice, ECHO revealed the development of an HFrEF-like phenotype later in life without detectable structural alterations. The transcriptomic profile revealed a sex-associated dichotomy in LV structure and function. Specifically, at 530-day, WD-fed male mice exhibited differentially expressed genes (DEGs), which were overrepresented in pathways associated with endocrine function, signal transduction, and cardiomyopathies. At 750 days, WD-fed male mice exhibited dysregulation of several genes involved in various lipid, glucagon, and glutathione metabolic pathways. At 530 days, WD-fed female mice exhibited the most distinctive set of DEGs with an abundance of genes related to circadian rhythms. At 640 days, altered DEGs in WD-fed female mice were associated with cardiac energy metabolism and remodeling. CONCLUSIONS: Our study demonstrated distinct sex-specific and age-associated differences in cardiac structure, function, and transcriptome signature between WD-fed male and female mice.

Authors: A. Stepanyan, A. Brojakowska, R. Zakharyan, S. Hakobyan, S. Davitavyan, T. Sirunyan, G. Khachatryan, M. K. Khlgatian, M. Bisserier, S. Zhang, S. Sahoo, L. Hadri, A. Rai, V. N. S. Garikipati, A. Arakelyan, D. A. Goukassian

Date Published: 28th Dec 2024

Publication Type: Journal

Association of Inflammasome Gene Expression Levels with Pathogenesis of Familial Mediterranean Fever in Armenians

Abstract (Expand)

Mediterranean fever (FMF) is a genetically determined autoinflammatory disease transmitted mostly by an autosomal recessive mechanism and caused by point mutations of the MEFV (Mediterranean FeVer) … gene. The aim of this study was to evaluate the expression of inflammasome genes (p65, Casp1, MEFV, and NLRP3) in patients with FMF compared to controls to understand the changes playing a key role in disease development. We found altered expression levels of the full-length MEFV isoform as well as Casp1 and p65 in FMF patients versus controls. This, once again, highlighted the significance of inflammasome genes in terms of FMF.

Authors: Varduhi Hayrapetyan, Lana Karapetyan, Lilit Ghukasyan, Sofi Atshemyan, Hovsep Ghazaryan, Valentina Vardanyan, Vahan Mukuchyan, Arsen Arakelyan, Roksana Zakharyan

Date Published: 2nd Dec 2024

Publication Type: Journal

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