Biology subjects

Pavlopoulou, A.

Publications and source records attributed to Pavlopoulou, A..

5 recordsLinked to original sources

bioRxiv2026

An integrative cardio-informatics approach identifies positionally conserved ancestors of human lncRNA genes transcribed across vertebrate hearts

The poor conservation of lncRNA genes limits their comprehensive functional studies, as genetic engineering of relevant animal models presupposes the presence of corresponding defined orthologs. This limitation is prominently evident in cardiovascular research, where heart-related lncRNAs are rarely conserved between humans and other vertebrates, despite the highly conserved nature of cardiac function. Because lncRNAs frequently regulate neighboring protein-coding genes essential for cardomyocyte function (herein termed cardiomyocyte indispensable, CMIs), we hypothesized that they are under evolutionary pressure to retain their genomic position and transcriptional activity, irrespective of sequence similarities to prototypical human lncRNA genes. By integrating mouse cardiac knockout phenotypes with human single-cell transcriptomics data, we systematically identified heart-expressed CMIs and their neighboring. lncRNA genes. Cross-species synteny analyses revealed regions flanking 109 CMIs with conserved relative positions and transcriptional orientations across vertebrate genomes. As most of these loci reside within poorly annotated non-coding regions, we developed VertLncRNAchecker, a neural network-based web interface, that predicts lncRNA-like genes within these regions, which we termed positional ancestors. Finally, we validated in situ that these positional ancestors express mature lncRNA transcripts in the hearts of mice, pigs, and frogs, mirroring the expression of their human lncRNA counterparts. We present an accurate and retrainable computational platform for cross-species lncRNA discovery that prioritizes conserved genomic position over sequence conservation or existing genome annotations. This pipeline revealed putative ancestors of human heart-related lncRNAs hidden within the vertebrate non-coding dark genome, providing novel insights into lncRNA biology and evolution.

evolutionary biology↗

bioRxiv2026

In situ vaccine effect of radiotherapy is associated with intratumoural ERV reactivation and RNA virus sensing

Radiotherapy (RT) transforms tumour tissues into in situ vaccines that trigger antitumor immunity. Immunogenicity depends on how RT is delivered, since heterogeneous RT (spatially fractionated RT, SFRT) elicits more prominent responses than the conventional homogenous one. However, this phenomenon cannot be clinically harnessed, unless the relevant pathways are identified. To gain insights, we developed a hybrid dry-lab/wet-lab approach that integrates systems-level immune phenotypes established by homogenous or heterogenous RT (SFRT) with the transcriptomic profiling of irradiated tumors. By further combining feature extraction with machine-learning, including multilayer perceptron modelling, we ranked predictors of immune infiltration and patient survivability for each RT type. We found that conventional RT induces coordinated upregulation of cytosolic sensors of RNA viruses (OASes and RIG I-like receptors) along with ERV RNAs predominately 400-800 base-pairs long, which might serve as their ligands. For schemes establishing abscopal effects, a coordinated upregulation of the OAS sensors and shared ERV transcripts was observed in both irradiated and distant tumours. Compared to homogenous RT, SFRT triggered earlier and stronger activation of OAS signaling along with NK cell responses. Overall, we show a co-involvement of tumour cell-intrinsic ERVs and their cytosolic RNA sensors in RT-induced antitumor immunity. This key finding could guide mechanistic studies and future precision oncology.

cancer biology↗

bioRxiv2020

Temporal evolution and adaptation of SARS-COV 2 codon usage

The outbreak of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) has caused an unprecedented pandemic. Since the first sequenced whole-genome of SARS-CoV-2 on January 2020, the identification of its genetic variants has become crucial in tracking and evaluating their spread across the globe. In this study, we compared 134,905 SARS-CoV-2 genomes isolated from all affected countries since the outbreak of this novel coronavirus with the first sequenced genome in Wuhan, China to quantify the evolutionary divergence of SARS-CoV-2. Thus, we compared the codon usage patterns of SARS-CoV-2 genes encoding the membrane protein (M), envelope (E), spike surface glycoprotein (S), nucleoprotein (N), RNA-dependent RNA polymerase (RdRp). The polyproteins ORF1a and ORF1b were examined separately. We found that SARS-CoV-2 tends to diverge over time by accumulating mutations on its genome and, specifically, on the sequences encoding proteins N and S. Interestingly, different patterns of codon usage were observed among these genes. Genes S and N tend to use a narrower set of synonymous codons that are better optimized to the human host. Conversely, genes E and M consistently use the broader set of synonymous codons, which does not vary in respect to the reference genome. CAI and SiD time evolutions show a tendency to decrease that emerge for most genes. Forsdyke plots are used to study the nature of mutations and they show a rapid evolutionary divergence of each gene, due to the low values of x-intercepets.

genomics↗

bioRxiv2020

Analysis of codon usage and evolutionary rates of the 2019-nCoV genes

Severe acute respiratory syndrome coronavirus 2 (2019-nCoV), which first broke out in Wuhan (China) in December of 2019, causes a severe acute respiratory illness with a mortality ranging from 3% to 6%. To better understand the evolution of the newly emerging 2019-nCoV, in this paper, we analyze the codon usage pattern of 2019-nCoV. For this purpose, we compare the codon usage of 2019-nCoV with that of other 30 viruses belonging to the subfamily of orthocoronavirinae. We found that 2019-nCoV shows a rich composition of AT nucleotides that strongly influences its codon usage, which appears to be not optimized to human host. Then, we study the evolutionary pressures influencing the codon usage and evolutionary rates of the sequences of five conserved genes that encode the corresponding proteins (viral replicase, spike, envelope, membrane and nucleocapsid) characteristic of coronaviruses. We found different patterns of both mutational bias and nature selection that affect the codon usage of these genes at different extents. Moreover, we show that the two integral membrane proteins proteins (matrix and envelope) tend to evolve slowly by accumulating nucleotide mutations on their genes. Conversely, genes encoding nucleocapsid (N), viral replicase and spike proteins are important targets for the development of vaccines and antiviral drugs, tend to evolve faster as compared to other ones. Taken together, our results suggest that the higher evolutionary rate observed for these two genes could represent a major barrier in the development of antiviral therapeutics 2019-nCoV.

genomics↗

bioRxiv2020

Codon usage bias in radioresistant bacteria

The relationship between patterns of codon usage bias (CUB), the preferential usage of synonimous nucleotide triplets encoding the same amino acid, and radioresistance was investigated int he genomes of 16 taxonomically distinct radioresistant prokaryotic organisms and in a control set of 11 non-radioresistant bacteria. The radioresistant species were found to be strongly biased towards G and C in the third synonimous codon position. ENC and neutrality plots also sugest that CUB in radioresistant bacteria is mainly affected by mutational bias. Furthermore, the availability of tRNA gene copy number was analyzed and it was found that nine radioresistant species have the sam number of tRNA gene copies for each codon. This suggests that tRNA gene copies and codon bias co-evolved in a specific way in radioresistant species.

molecular biology↗