bioRxiv Science⌕ Search

Biology subjects

Aguirre, J.

Publications and source records attributed to Aguirre, J..

6 recordsLinked to original sources

Induced Estrogen Receptor SUMOylation drives SERD activity

The ligand dependent transcription factor estrogen receptor (ER) is a key driver of and important drug target in breast cancer. Patients with advanced disease are typically treated with selective ER degraders (SERDs), whose therapeutic activity is commonly attributed to induced ER protein degradation. Yet the exact mechanism and relevance of degradation for clinical efficacy remain unclear. We show that SERDs directly induce ER SUMOylation, thereby triggering degradation via SUMO-targeted ubiquitin ligases (STUbLs). Inactivation of STUbLs prevents ER degradation and counterintuitively further sensitizes breast cancer cells to SERDs, rather than conferring resistance. SERD efficacy is independent of ER degradation, challenging the degradation-centric model of SERD action. Instead, SUMOylation recruits transcriptional co-repressors, turning SUMOylated ER into a dominant-negative repressor. Thus, SUMOylation rather than degradation is the direct consequence and driver of SERD activity. Our findings position SUMO-inducing drugs as a hitherto underappreciated yet clinically validated therapeutic modality with broad applicability.

Cancer Biology↗

Virus-host protein co-expression networks reveal temporal organization and strategies of viral infection

Viral replication is a complex dynamical process involving the global remodelling of the host cellular machinery across several stages. In this study, we provide a unified view of the virus-host interaction at the proteome level reconstructing protein co-expression networks from quantitative temporal data of four large DNA viruses. We take advantage of a formal framework, the theory of interacting networks, to describe the viral infection as a dynamical system taking place on a network of networks where perturbations induced by viral proteins spread to hijack the host proteome for the virus benefit. Our methodology demonstrates how the viral replication cycle can be effectively examined as a complex interaction between protein networks, providing useful insights into the viral and hosts temporal organization and strategies, key protein nodes targeted by the virus and dynamical bottlenecks during the course of the infection.

systems biology↗

Defective subviral particles modify ecological equilibria and enhance viral coexistence

Cooperation is a main driver of biological complexity at all levels. In the viral world, gene sharing among viral genomes, complementation between genomes or interactions within quasispecies are frequently observed. In this contribution, we explore the advantages that flexible associations between fully fledged viruses and subviral entities, such as virus satellites, might yield. We devise a mathematical model to compare different situations of competition between two viruses and to quantify how the association with a satellite qualitatively modifies dynamical equilibria. The relevant parameter is the invasion fitness of each virus or of the virus-satellite tandem, which in the model depends on the transmission rate of viruses and on their effect on host survival. While in a virus-virus competition one of the viruses becomes eventually extinct, an association with a satellite might change the outcome of the competition to favor the less competitive virus (regardless of whether it is the helper virus or not) or to allow for the stable coexistence of the two viruses and the satellite. We hypothesize that the latter scenario, in particular, constitutes a parsimonious evolutionary pathway towards more stable cooperative associations, such as bipartite viral forms.

ecology↗

Choosing variant interpretation tools for clinical applications: context matters

Our inability to solve the Variant Interpretation Problem (VIP) has become a bottleneck in the biomedical/clinical application of Next-Generation Sequencing. This situation has favored the development and use of bioinformatics tools for the VIP. However, choosing the optimal tool for our purposes is difficult because of the high variability of clinical contexts across and within countries. Here, we introduce the use of cost models as a new approach to compare pathogenicity predictors that considers clinical context. An interesting feature of this approach, absent in standard performance measures, is that it treats pathogenicity predictors as rejection classifiers. These classifiers, commonly found in machine learning applications to healthcare, reject low-confidence predictions. Finally, to explore whether context has any impact on predictor selection, we have developed a computational procedure that solves the problem of comparing an arbitrary number of tools across all possible clinical scenarios. We illustrate our approach using a set of seventeen pathogenicity predictors for missense variants. Our results show that there is no optimal predictor for all possible clinical scenarios. We also find that considering rejection gives a view of classifiers contrasting with that of standard performance measures. The Python code for comparing pathogenicity predictors across the clinical space using cost models is available to any interested user at: https://github.com/ClinicalTranslationalBioinformatics/clinical_space_partition SummariesJosu Aguirre earned his doctorate at the Clinical and Translational Bioinformatics group, at the Vall dHebron Institute of Research (VHIR). Natalia Padilla earned is a post-doctoral researcher at the Clinical and Translational Bioinformatics group, at the Vall dHebron Institute of Research (VHIR). Selen Ozkan is a Ph.D. student at the Clinical and Translational Bioinformatics group, at the Vall dHebron Institute of Research (VHIR). Casandra Riera earned her doctorate at the Clinical and Translational Bioinformatics group, at the Vall dHebron Institute of Research (VHIR). Lidia Feliubadalo earned her doctorate at the Universitat de Barcelona, presently she is a high-level technician working at the Catalan Institute of Oncology (ICO) in the diagnosis of hereditary cancers. Xavier de la Cruz is ICREA Research Professor at the Vall dHebron Institute of Research (VHIR). His research interests revolve around the application of machine learning methods to healthcare problems.

bioinformatics↗

Fast Optoacoustic Mesoscopy of Microvascular Endothelial Dysfunction in Cardiovascular Risk and Disease

Microvascular endothelial dysfunction (ED) precedes the ED in larger arteries and is an early marker of cardiovascular disease (CVD). While precise assessment of microvascular ED could thus be used for the early detection and risk stratification of CVD, detailed interrogation of skin microvascular ED is limited by the technology available. Herein, we applied a novel approach for the non-invasive assessment of skin microvascular ED by developing fast plane raster-scan optoacoustic mesoscopy (FP-RSOM) to visualize and quantify skin microvasculature perfusion changes during post-occlusive hyperemia (PORH) tests. We combined static three-dimensional RSOM imaging with fast dynamic FP-RSOM measurements (1 frame / second) in human skin in vivo, which allowed for the first time to fully visualize the cutaneous microvascular response and further quantify changes of individual vessel diameter, total blood volume and vessel density during the PORH process. We further computed biomarkers from FP-RSOM images to quantify skin endothelial function within different skin layers as a function of skin depth, while conventional approaches mainly measure overall changes within sampled tissue volumes. FP-RSOM applied on smokers and patients with CVD showed clear ED in both groups compared to healthy volunteers. Moreover, FP-RSOM imaging showed higher sensitivity in quantifying the effects of smoking and CVD on skin microvascular endothelial function compared to clinically used laser Doppler flowmetry and tissue spectrometry (O2C). Our study introduces FP-RSOM as a novel tool to visualize and quantify skin microvascular ED as an early marker for the diagnostics and monitoring of cardiovascular risk and disease.

bioengineering↗

Synergistic Recruitment of UbcH7~Ub and Phosphorylated Ubl Domain Triggers Parkin Activation

The mechanism of activation and ubiquitin conjugation by the E3 ligase parkin is pivotal to understand the molecular pathology of early-onset Parkinsons disease. Parkin is normally autoinhibited but is activated by the kinase PINK1 that phosphorylates parkins N-terminal ubiquitin-like (pUbl) domain and ubiquitin. How these alter the structure of parkin to allow recruitment of an E2~Ub conjugate to enhance ubiquitination is an unresolved question. We present the structure of an incoming E2~Ub conjugate with the phospho-ubiquitin bound C-terminus of parkin (R0RBR). We show the UbcH7~Ub conjugate is recruited by R0RBR parkin in the open state whereby conjugated ubiquitin binds to the RING1/IBR interface. Further, NMR experiments indicate there is re-modelling near the RING0/RING2 interface remote from the E2-binding site. This, and parkin phosphorylation lead to rapid reactivity of the RING2(Rcat) catalytic cysteine in parkin, needed for ubiquitin transfer. Parkin phosphorylation also leads to relocation and weak interaction of the pUbl domain with the RING0 domain that is enhanced upon E2~Ub recruitment indicating these events act synergistically to drive parkin activity.

biochemistry↗