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Oliva, B.

Publications and source records attributed to Oliva, B..

At least 19 recordsLinked to original sources

ModCRE-NN: Interpretable Deep Learning Harnesses Structural and Evolutionary Synergy to Predict Transcription Factor Binding Specificity

We present ModCRE-NN, a machine-learning framework and server for predicting transcription-factor (TF) DNA-binding motifs through the integration of structural and evolutionary information. The method combines structure-derived Position Weight Matrices (PWMs) together with PWMs of homologous spanning multiple evolutionary sequence-identity intervals, which are integrated into a unified 20-channel tensor representation. Benchmark datasets were constructed on experimental databases of TF motifs, showing DNA binding specificity, while redundancy reduction and strict train/test partitioning minimized homology leakage. Prediction quality was evaluated on an independent separated set of TFs using the similarity analysis of profiles. Three complementary architectures were implemented and evaluated: an interpretable regression-based model, a convolutional neural network (CNN), and a Transformer-based architecture using self-attention mechanisms. The regression model achieved strong performance in high-homology regimes dominated by closely related PWMs, whereas CNN and Transformer architectures showed superior robustness under low evolutionary similarity and increased structural uncertainty. Importantly, AI-generated motifs consistently improved the similarity-scores while reducing prediction variance relative to the original structural and evolutionary input motifs, indicating that the models effectively denoise heterogeneous motif assemblies and reconstruct stable consensus DNA-binding representations rather than simply transferring PWMs from the nearest homolog. The CNN model exhibited the most balanced attribution profile, suggesting enhanced ability to combine weak structural and evolutionary signals into coherent motif representations. Additionally, we implemented a prediction-reliability framework combining Random Forest regression, exponential interpolation, and hybrid residual-corrected modeling to estimate the quality and uncertainty of the PWMs as functions of evolutionary similarity, motif-cluster consistency, and TF-family context. Overall, our results demonstrate that integrating structural information with deep learning provides a robust framework for large-scale TF-binding specificity prediction under conditions of substantial evolutionary divergence and motif uncertainty.

bioinformatics↗

ExoFILT: Transfer learning for robust and accelerated analysis of exocytosis single-particle tracking data

MotivationUnderstanding constitutive exocytosis at the molecular level requires quantitative characterization of protein dynamics during the process. Single-particle tracking allows the measurement of protein dynamics in living cells. However, identifying bona fide exocytic events requires extensive manual annotation, limiting throughput and introducing personal biases that affect reproducibility. ResultsWe present ExoFILT, a deep learning-based classifier designed to identify exocytic events in single-particle tracking data, using the exocyst complex as a reference. Trained via transfer learning on simulated and experimental data, ExoFILT reduces the time required for manual annotation by ten-fold while improving measurement consistency across researchers. When applied to simultaneous dual-color time-lapse movies, ExoFILT enabled the systematic quantification of temporal relationships between exocytic proteins. The increased throughput uncovered distinct subpopulations of exocytic events with differential molecular composition (e.g., events with and without detectable levels of Sec1), underscoring the potential of ExoFILT to reveal mechanistic insights into exocytosis.

bioinformatics↗

ModCRElib: A standalone package to model cis-regulatory elements.

SummaryThe ModCRElib package provides various tools for the analysis and modelling of transcription factor(TF)-DNA and regulatory complex inter-protein interactions. It takes structural information on these interactions to predict TF binding motifs, generate binding profiles along DNA sequences that score the binding affinity, predict TF binding sites and model the structure of higher order regulatory complexes. It is capable of working with a variety of input data formats and sources. The user may follow the analysis pipeline as outlined in the documentation or the user can make use of any of the multiple functionalities in an isolated manner. The package takes the service offered by the ModCRE server and enables users to apply its tools in an unrestricted and customizable manner. In this paper we provide 5 example uses of ModCRElib. This includes (i) TF binding affinity prediction, (ii) TF binding aggregation, (iii) characterization of specificity in TF binding sites along target DNA sequences,(iv) modelling TF bound to predicted binding sites, and (v) the generation of statistical potential derived scoring profiles of TF interacting with DNA. Availabilityhttps://github.com/structuralbioinformatics/ModCRElib Contactbaldo.oliva@upf.edu Supplementary informationAvailable at https://github.com/structuralbioinformatics/ModCRElib. doi:10.5281/zenodo.17484081

bioinformatics↗

Distinct DNA-binding syntax and chromatin remodeling capacities of bHLH transcription factors in cell differentiation, reprogramming and cancer

Basic helix-loop-helix (bHLH) transcription factors orchestrate cell differentiation, reprogramming, and oncogenic transformation, yet the molecular determinants that govern their DNA-binding specificity and capacity to remodel chromatin remain incompletely understood. Here, we assemble and unify all available bHLH induction ChIP-seq datasets (74 experiments covering 17 factors) and integrate them with matched chromatin accessibility, nucleosome positioning, CpG methylation, transcriptomic profiling, methyl-HT-SELEX, and structural modeling. Using an exact hexanucleotide-based approach, we define the sequence grammar that shapes bHLH-DNA interactions and identify distinct motif architectures associated with binding to accessible versus inaccessible chromatin. CAT- and CAG-preferring bHLH factors--including proneural and myogenic regulators--display robust pioneer-like behavior, characterized by preferential engagement of closed chromatin through specific E-box variants, cooperative motif clustering, and characteristic spacing patterns. TWIST factors exhibit a unique 5-bp E-box periodicity linked to dedifferentiation programs, whereas CAC-preferring oncogenic bHLHs remain largely restricted to open chromatin. By integrating methylation and SELEX data, we reveal that CpG methylation drives a systematic shift from the canonical CAC-CAC motif toward CAT-CAC E-boxes, providing a mechanistic explanation for MYC enhancer invasion in cancer and uncovering parallel behavior in the HEY family. Nucleosome chemical mapping and structural predictions further show that nearly all bHLH factors bind preferentially at nucleosome flanks, independent of -helix length, challenging prior models of nucleosomal engagement. Together, these results establish a unified framework linking sequence syntax, chromatin state, and transcriptional outcome across the bHLH family, providing mechanistic principles for understanding lineage specification, reprogramming, and oncogenic enhancer remodeling.

molecular biology↗

Network-Based Analysis of Human Astrocytes Links Aging to Neurodegenerative and Cardiovascular Diseases

Astrocytes are central to brain homeostasis, supporting neuronal metabolism, synaptic activity, and the blood-brain barrier. With aging, these glial cells undergo molecular and functional changes that weaken support functions and promote neuroinflammation, contributing to neurodegeneration. Yet the systems-level mechanisms of astrocytic aging remain poorly defined in human models. Because aging also heightens risk for cardiovascular disease, cognitive impairment, type 2 diabetes, and systemic inflammation, clarifying shared astrocytic pathways is critical for understanding brain-body crosstalk. Using an in vitro human astrocyte model exposed to sublethal oxidative stress (10 {micro}M H2O2), we profiled transcriptomic changes and identified differentially expressed genes across antioxidant defences, proteostasis, transcriptional regulation, vesicular trafficking, and inflammatory signalling. We then performed seven network-prioritization analyses on a curated human protein-protein interactome: one seeded with the astrocyte H2O2-responsive genes and six with phenotype-associated gene sets (Alzheimers disease, cardiovascular disease, cognitive impairment, type 2 diabetes, oxidative stress, and inflammation). Intersecting the top 5% scoring genes from each run yielded a 127-gene core shared across all seven, enriched for proteostasis, DNA repair, mitochondrial regulation, and telomere and nuclear envelope maintenance. Structure-guided analyses highlighted vulnerable interfaces, including lamin A/C-lamin B1, -actinin-filamins, 14-3-3 dimers, and aminoacyl-tRNA synthetase assemblies, where pathogenic variants are predicted to destabilize or aberrantly stabilize protein interactions. Structure-based interface predictions also highlight potential interactions between APP-VCP/p97 and p53-14-3-3{zeta} that link proteostasis and stress signalling. Together, these findings define a conserved astrocytic vulnerability network that may couple neurodegeneration with cardiovascular disease and nominate structurally testable targets for biomarkers and interventions.

bioinformatics↗

Phospho-eIF2B-epsilon links stress response-driven translation to amyloidogenesis in Alzheimer's disease

A central etiopathogenic event in Alzheimers disease (AD) is the accumulation of amyloid {beta}-peptide (A{beta}) derived from the amyloidogenic processing of the amyloid precursor protein, a pathway initiated by BACE1. Chronic activation of the Integrated Stress Response is linked to AD, typically through eIF2 phosphorylation, which selectively enhances translation of key stress-responsive mRNAs like ATF4 and BACE1. We investigated a novel regulatory mechanism mediated by Glycogen Synthase Kinase-3{beta} (GSK-3{beta}) a hyperactive kinase in AD, on the translational factor eIF2B, the guanine nucleotide exchange factor (GEF) for eIF2. The methodology combined cellular and molecular biology approaches (western blot, ELISA, immunofluorescence, and luciferase assays) using pharmacological inhibitors and plasmid transfection in established cell models, along with computational structural modeling (AlphaFold3). Findings were validated in post-mortem human brain tissue, with statistical analyses (t-tests and ANOVA) applied throughout. We treated cells (SH-SY5Y) with a GSK-3{beta} inhibitor (NP031112) or overexpressed a constitutively active GSK-3{beta} mutant (GSK-3{beta}-S9A) to modulate GSK-3{beta} activity. GSK-3{beta} inhibition significantly reduced ATF4 and BACE1 protein levels in SH-SY5Y cells in a dose-dependent manner as we tested by western blot (P<0.001), independent of eIF2 phosphorylation. This effect was translational, as the inhibitor still reduced BACE1 levels when transcription was blocked. Crucially, NP031112 reversed stress-induced eIF2B{varepsilon} phosphorylation at Ser540 (P<0.001). Furthermore, H2O2-induced A{beta}1-42 secretion by SH-SY5Y cells was significantly reversed by GSK-3{beta} inhibition (P<0.001). Luciferase reporter assays using the BACE1 5 untranslated region (5 UTR) confirmed that both eIF2B{varepsilon} silencing and a phosphomimetic mutant eIF2B{varepsilon}-S540E increased BACE1 5 UTR-driven translation (P<0.001), demonstrating that reduced functional eIF2B enhances BACE1 translation. Finally, immunohistofluorescence and western blot analysis of human AD hippocampi showed a significant increase in pS540-eIF2B{varepsilon}, ATF4, and BACE1 levels in AD patients compared to non-demented controls (P<0.001 for all three). Our findings establish a novel GSK-3{beta}-eIF2B{varepsilon}-BACE1 axis that links stress response dysregulation to amyloidogenesis, independent of canonical eIF2 phosphorylation. The phosphorylation of eIF2B{varepsilon} functionally mimics the effects of eIF2 phosphorylation by reducing the available functional eIF2B pool, thereby reprogramming translation to favour the production of stress proteins like ATF4 and BACE1. We proposed eIF2B{varepsilon} phosphorylation is a key etiological mechanism in AD.

neuroscience↗

Profiling of Vaginal Microbial Communities in Chilean Women Via Self-sampling and Full-length 16S rRNA Sequencing

The vaginal microbiota is a dynamic ecosystem that plays a crucial role in womens health, with Lactobacillus species predominating in healthy individuals. Disruptions in this microbiota can lead to dysbiosis, increasing susceptibility to infections such as bacterial vaginosis and other reproductive health complications. While most studies on the vaginal microbiome have been conducted in North American and European populations, data from Latin America, particularly Chile, remain scarce. This study presents a comprehensive analysis of the vaginal microbiota in Chilean women using full-length 16S rRNA gene sequencing with Oxford Nanopore Technology (ONT). We implemented a self-sampling methodology and a bioinformatics pipeline to achieve species-level resolution of microbial communities. Taxonomic profiling using Emu revealed that Lactobacillus was the dominant genus in most samples, while others exhibited microbial compositions consistent with Community State Type (CST) IV, characterized by higher diversity and lower Lactobacillus abundance. Alpha and beta diversity analyses further demonstrated distinct microbial clustering patterns across CSTs, with species-level resolution providing enhanced classification accuracy. Our findings highlight the potential of long-read sequencing and self-sampling for improving vaginal microbiome studies, particularly in underrepresented populations. This research contributes valuable insights into the composition and diversity of the vaginal microbiota in Chilean women, paving the way for more precise diagnostics and targeted interventions in reproductive health.

microbiology↗

Continuum architecture dynamics of vesicle tethering in exocytosis

Essential for eukaryotic organisms, multiple copies of the exocyst complex tether each secretory vesicle to the plasma membrane (PM) in constitutive exocytosis. The exocyst higher-order structure (ExHOS) that coordinates the action of these multiple exocysts remains unexplored. We integrated particle-tracking, super-resolution microscopy and cryo-electron tomography in a model that time-resolves the continuum conformational landscape of the ExHOS and functionally annotates its different conformations. We found that 7 exocysts form flexible ring-shaped ExHOS that tether vesicles at <45 nm from the PM. The ExHOS, initially 19 nm in radius, rapidly expands while it pulls the vesicle towards the PM. Subsequently, the ExHOS stabilizes, securing the vesicle at [~]4 nm from the PM. After fusion, Sec18 mediates the ExHOS disassembly when its radius is 38 nm. By resolving the fundamental biophysical principles of tethering we bridged the gap between static isolated structures and the dynamic and multimeric nature of exocytosis.

cell biology↗

Integration of expression datasets to identify biomarkers for accurate Gleason scoring in Prostate Cancer

Prostate cancer is a significant global health issue with considerable mortality rates, emphasising the urgent need for advanced treatment options and improved diagnostic methods. Current diagnostic standards for prostate cancer, including PSA testing and digital rectal examination, often produce false positives, resulting in unnecessary biopsies for patients. This limitation highlights the critical requirement to incorporate more precise biomarkers to enhance diagnostic accuracy and reduce unnecessary procedures. This study aims to investigate biomarker candidates that can effectively determine prostate cancer aggressiveness. By integrating diverse prostate tissue expression datasets and employing machine-learning techniques, this approach seeks to refine diagnostics and provide insights into the molecular underpinnings of the disease, potentially transforming early detection and patient management strategies. Our proposed biomarkers achieve a minimum precision of 0.80, addressing the false positives limitations associated with classical prostate cancer biomarkers. Moreover, the ROC-AUC profiles of most of the candidates proposed in this study align with those exhibited by other innovative biomarkers recently proposed (ROC-AUC [&ge;] 0.70). We believe these biomarkers are promising candidates for further in vivo and in vitro investigation.

cancer biology↗

PyF2F: A robust and simplified fluorophore-to-fluorophore distance measurement tool for Protein interactions from Imaging Complexes after Translocation experiments

SummaryStructural knowledge of protein assemblies in their physiological environment is paramount to understand cellular functions at the molecular level. Protein interactions from Imaging Complexes after Translocation (PICT) is a live-cell imaging technique for the structural characterization of macromolecular assemblies in living cells. PICT relies on the measurement of the separation between labelled molecules using fluorescence microscopy and cell engineering. Unfortunately, the required computational tools to extract molecular distances involve a variety of sophisticated software that challenge reproducibility and limit their implementation by highly specialised researchers. Here we introduce PyF2F, a Python-based software that provides a workflow for measuring molecular distances from PICT data, with minimal user programming expertise. We used a published dataset to validate PyF2F performance.

bioinformatics↗

PREDICTING GENE DISEASE ASSOCIATIONS WITH KNOWLEDGE GRAPH EMBEDDINGS FOR DISEASES WITH CURTAILED INFORMATION

Knowledge graph embeddings (KGE) are a powerful technique used in the biological domain to represent biological knowledge in a low dimensional space. However, a deep understanding of these methods is still missing, and in particular the limitations for diseases with reduced information on gene-disease associations. In this contribution, we built a knowledge graph (KG) by integrating heterogeneous biomedical data and generated KGEs by implementing state-of-the-art methods, and two novel algorithms: DLemb and BioKG2Vec. Extensive testing of the embeddings with unsupervised clustering and supervised methods showed that our novel approaches outperform existing algorithms in both scenarios. Our results indicate that data preprocessing and integration influence the quality of the predictions and that the embeddings efficiently encodes biological information when compared to a null model. Finally, we employed KGE to predict genes associated with Intervertebral disc degeneration (IDD) and showed that functions relevant to the disease are enriched in the genes prioritized from the model GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=110 SRC="FIGDIR/small/575314v1_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@1ba98b7org.highwire.dtl.DTLVardef@1801d6borg.highwire.dtl.DTLVardef@b87a7org.highwire.dtl.DTLVardef@f70cf8_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioinformatics↗

Genopyc: a python library for investigating the genomic basis of complex diseases

MotivationUnderstanding the genetic basis of complex diseases is a paramount challenge in modern genomics. However, current tools often lack the versatility to efficiently analyze the intricate relation-ships between genetic variations and disease outcomes. To address this, we introduce Genopyc, a novel Python library designed for comprehensive investigation of the genetics underlying complex dis-eases. Genopyc offers an extensive suite of functions for heterogeneous data mining and visualization, enabling researchers to delve into and integrate biological information from large-scale genomic da-tasets with ease. ResultsIn this study, we present the Genopyc library through application to real-world genome wide association studies variants. Using Genopyc to investigate variants associated to intervertebral disc degeneration (IDD) enabled a deeper understanding of the potential dysregulated pathways involved in the disease, which can be explored and visualized by exploiting the functionalities featured in the package. Genopyc emerges as a powerful asset for researchers, fostering advancements in the un-derstanding of complex diseases and thus paving the way for more targeted therapeutic interventions. Availability: Genopyc is available at pip (https://pypi.org/project/genopyc/) and the source code of Genopyc is available at https://github.com/freh-g/genopyc Contactfrancesco.gualdi01@estudiant.upf.edu Supplementary informationsupplementary data are available at Bioinformatics online.

bioinformatics↗

Recruitment of Homodimeric Proneural Factors by Conserved CAT-CAT E-Boxes Drives Major Epigenetic Reconfiguration in Cortical Neurogenesis

The proneural factors of the basic-helix-loop-helix (bHLH) family of transcription factors coordinate early processes of neurogenesis and neurodifferentiation. Among them, Neurog2 and Neurod2 subsequently act specifying neurons of the glutamatergic lineage. The disruption of proneural factors, their target genes, and the DNA motifs they bind, have been linked to various neuropsychiatric disorders. Proneural factors operate on the DNA forming homodimers or heterodimers with other bHLH factors and binding to specific motifs called E-boxes, which are hexanucleotides of the form CANNTG, composed of two CAN half sites on opposed strands. These E-box motifs are highly enriched in regulatory elements that become active during corticogenesis. Although neurogenesis and neurodifferentiation appear to rely heavily on the activity of E-boxes, our understanding of the specific dynamics of DNA binding and partner usage throughout neurogenesis and neurodifferentiation remains largely unknown. To shed light on this critical facet of neural development, we conducted a comprehensive analysis leveraging ChIP-seq data of NEUROG2 and NEUROD2, paired with time-matched single-cell RNA-seq and ATAC-seq assays and DNA methylation data, collected from the developing mouse brain. Our analyses revealed that distinct trajectories of chromatin accessibility are selectively linked to specific subsets of NEUROG2 and NEUROD2 binding sites and E-boxes. Notably, while E-boxes composed of CAT-CAG half sites or two CAG half sites are more commonly found within their binding sites, E-boxes consisting of two CAT half sites exhibit a striking enrichment in developmentally dynamic enhancers. These CAT-CAT E-boxes also manifest substantial DNA demethylation effects throughout the process of neurodifferentiation and display the highest levels of evolutionary constraint. Aided by a combination of a detailed DNA-footprinting and structural modeling approach, we propose a compelling model to explain the combinatorial action of bHLH factors across the various stages of neurogenesis. Finally, we hypothesize that NEUROD2 acts as a chromatin remodeler in cortical neurodifferentiation by binding CAT-CAT E-boxes as a homodimer, a mechanism that could be extended to other members of this bHLH class of transcription factors.

neuroscience↗

Revealing Shared Proteins and Pathways in Cardiovascular and Cognitive Diseases Using Protein Interaction Network Analysis

One of the primary goals of systems medicine is detecting putative proteins and pathways involved in disease progression and pathological phenotypes. Vascular Cognitive Impairment (VCI) is a heterogeneous condition manifesting as cognitive impairment resulting from vascular factors. The precise mechanisms underlying this relationship remain unclear, which poses challenges for experimental research. Here, we applied computational approaches like systems biology to unveil and select relevant proteins and pathways related to VCI by studying the crosstalk between cardiovascular and cognitive diseases. In addition, we specifically included signals related to oxidative stress, a common etiologic factor tightly linked to aging, a major determinant of VCI. Our results show that pathways associated with oxidative stress are quite relevant, as most of the prioritized vascular-cognitive genes/proteins were enriched in these pathways. Our analysis provided a short list of proteins that could be contributing to VCI: DOLK, TSC1, ATP1A1, MAPK14, YWHAZ, CREB3, HSPB1, PRDX6, and LMNA. Moreover, our experimental results suggest a high implication of glycative stress, generating oxidative processes and post-translational protein modifications through advanced glycation end-products (AGEs). We propose that these products interact with their specific receptors (RAGE) and Notch signaling to contribute to the etiology of VCI.

systems biology↗

Ancient loss of catalytic selenocysteine spurred convergent adaptation in a mammalian oxidoreductase

Selenocysteine (Sec), the 21st amino acid specified by the genetic code, is a rare selenium-containing residue found in the catalytic site of selenoprotein oxidoreductases. Sec is analogous to the common cysteine (Cys) amino acid but its selenium atom offers physicalchemical properties not provided by the corresponding sulfur atom in Cys. Catalytic sites with Sec in selenoproteins of vertebrates are under strong purifying selection but one enzyme, Glutathione Peroxidase 6 (GPX6), independently exchanged Sec for Cys less than one hundred million years ago in several mammalian lineages. We reconstructed and assayed these ancient enzymes before and after Sec was lost and up to today, and found them to have lost their classic ability to reduce hydroperoxides using glutathione (GSH). This loss of function, however, was accompanied by bursts of amino acid changes in the catalytic domain, with protein sites concertedly changing under positive selection across distant lineages abandoning Sec in GPX6. This demonstrates that when sulfur in Cys impairs catalysis a narrow evolutionary path is followed, with epistasis and pleiotropy leading to convergent evolution and triggering enzymatic properties likely beyond those in classic GPXs. These findings are an unusual example of adaptive convergence towards unexplored oxidoreductase functions during mammalian evolution.

molecular biology↗

The usage of transcriptomics datasets as sources of Real-World Data for clinical trialling

BackgroundRandomised Clinical Trials (RCT) reflect results within their specific controlled settings, necessitating further studies to understand outcomes across all possible scenarios. The usage of Real-World Data (RWD) has been recently considered to be a viable alternative to overcome these issues and complement clinical conclusions. Molecular profiles of patients captured by high-throughput measures reflect their medical conditions. When this information is linked to clinical and demographical information, nuances in transcriptomics data can uncover subtle variations in disease pathways among distinct patient groups. This work focuses on the construction of a patient repository database with molecular and clinical information resulting from the integration of publicly available transcriptomics datasets. ResultsPatient data were integrated into the patient repository by using a novel post-processing technique allowing for the usage of samples originating from different/multiple Gene Expression Omnibus (GEO) datasets. Our post-processing technique, which we have named MicroArray Cross-plAtfoRm pOst-prOcessiNg (MACAROON), aims to standardise and integrate transcriptomics data (considering batch effects and possible processing-originated artefacts). This process was able to better reproduce the down streaming biological conclusions in a 45% improvement compared to other methods available. Furthermore, RWD was mined from GEO samples metadata and a clinical and demographical characterisation of the database was obtained. RWD mining was done through a manually curated synonym dictionary allowing for the correct assignment (95.33% median accuracy; 80.14% average) of medical conditions. ConclusionsOur strategy produced a repository, which includes molecular, clinical and demographical RWD by integrating multiple public datasets. The exploration of these data facilitates the discovery of clinical outcomes and molecular pathways specific to predetermined patient populations.

bioinformatics↗

Schlafen 12 restricts HIV-1 latency reversal by a codon-usage dependent post-transcriptional block in CD4+ T cells

Latency is a major barrier towards virus elimination in HIV-1-infected individuals. Yet, the mechanisms that contribute to the maintenance of HIV-1 latency are incompletely understood. Here we describe the Schlafen 12 protein (SLFN12) as an HIV-1 restriction factor that establishes a post-transcriptional block in HIV-1-infected cells and thereby inhibits HIV-1 replication and virus reactivation from latently infected cells. The inhibitory activity is dependent on the HIV-1 codon usage and on the SLFN12 RNase active sites. Within HIV-1- infected individuals, SLFN12 expression in PBMCs correlated with HIV-1 plasma viral loads and proviral loads suggesting a link with the general activation of the immune system. Using an RNA FISH-Flow HIV-1 reactivation assay, we demonstrate that SLFN12 expression is enriched in infected cells positive for HIV-1 transcripts but negative for HIV-1 proteins. Thus, codon-usage dependent translation inhibition of HIV-1 proteins participates in HIV-1 latency and can restrict the amount of virus release after latency reversal.

immunology↗

Evolutionary insights reveal a new role of PADI2 in transcriptional elongation

Peptidyl arginine deiminases (PADIs) catalyze protein citrullination, a post-translational conversion of arginine to citrulline. The most widely expressed member of this family, PADI2, regulates cellular processes that impact several diseases. We hypothesized that we could gain new insights into PADI2 function through a systematic evolutionary and structural analysis. Here, we identify 20 positively selected PADI2 residues, 16 of which are structurally exposed and maintain PADI2 interactions with cognate proteins. Many of these selected residues reside in non-catalytic regions of PADI2. We validate the importance of a prominent loop in the middle domain that encompasses PADI2 L162, a residue under positive selection. This site is essential for interaction with the transcription elongation factor (P-TEFb) and mediates active transcription of the oncogenes c-MYC, and CCNB1, as well as impacting cellular proliferation. These insights could be key to understanding and addressing the role of the PADI2 c-MYC axis in cancer progression. Significance StatementHere we use a systematic evolutionary analysis to identify positively selected residues in the non-catalytic domain of PADI2 and link the positive selection of key residues to a role in transcription. Specifically, a structurally exposed loop in the PADI2 middle domain encompasses the positively selected residue L162 which is linked to transcription and cellular proliferation. This loop contributes to PADI2 interaction with the P-TEFb complex and cellular proliferation. Our results showcase the utility of combining evolutionary and experimental approaches to dissect the evolution of essential functional processes.

evolutionary biology↗