Biology subjects

Izquierdo, M.

Publications and source records attributed to Izquierdo, M..

6 recordsLinked to original sources

bioRxiv2026

Anti-trypanosomal activity and target validation of the M17 leucyl-aminopeptidase inhibitor DDD00057570 in Trypanosoma cruzi

Background: Chagas disease, caused by the parasite Trypanosoma cruzi, affects six to seven million people, and its treatment still relies on two drugs introduced more than fifty years ago, both of limited efficacy and poorly tolerated. The major acidic M17 leucyl-aminopeptidase of T. cruzi is expressed in all developmental stages of the parasite and has been proposed as a drug target, but it has not been pharmacologically validated. Methodology/Principal Findings: We assessed DDD00057570, a compound originally identified as an inhibitor of the orthologue enzyme of Leishmania major, against the recombinant T. cruzi enzyme and against the parasite. The compound inhibited the recombinant enzyme with an IC50 of 2.7 {+/-} 0.9 {micro}M and reduced the proliferation of insect-stage epimastigotes, with a half-maximal effective concentration of 3.7 {+/-} 1.1 {micro}M. Parasites engineered to overexpress the enzyme were twice as resistant to the compound as wild-type parasites, indicating that the enzyme is a primary target in the living parasite. Treatment increased the proportion of epimastigotes with fragmented DNA. In infected mammalian cells, the compound reduced the release of trypomastigotes, the stage responsible for dissemination in the mammalian host, with a half-maximal effective concentration of 1.3 {+/-} 0.6 {micro}M, while its half-maximal cytotoxic concentration on CHO-K1 mammalian host cells was 41.5 {+/-} 3.9 {micro}M, resulting in a selectivity index of approximately 32. Conclusions/Significance: These results validate the major M17 leucyl-aminopeptidase as a drug target in T. cruzi through target overexpression, and identify DDD00057570 as a selective lead structure warranting mechanistic, pharmacokinetic and in vivo studies toward a new treatment for Chagas disease.

microbiology↗

bioRxiv2026

A biatrial digital twin integrating electrophysiology, mechanics, and circulation: from physiology to atrial fibrillation

Atrial electromechanics plays a key role in cardiac function by regulating ventricular filling and global hemodynamics, yet remains challenging to model consistently across scales. In this work, a multiscale atrial digital twin for simulations of normal and pathological atrial function is presented, formulated as an electromechanical framework for biatrial simulations that couples three-dimensional atrial electrophysiology and mechanics with a closed-loop zero-dimensional circulatory model. The framework is calibrated on a patient-specific biatrial anatomy to reproduce physiological regional activation times, atrial volumes, ejection fractions, and pressure-volume loop characteristics. The simulations capture all atrial functional phases throughout the cardiac cycle, including realistic figure-eight pressure-volume loops, an aspect hard to achieve in computational studies. A systematic sensitivity analysis quantifies the influence of active contraction, passive stiffness, boundary conditions, and circulatory parameters on atrial function. Finally, application to a pathological scenario through induced persistent atrial fibrillation demonstrates how electrophysiological remodelling propagates across scales, leading to loss of effective atrial contraction, altered atrioventricular flow patterns, and a clinically relevant reduction in cardiac output. Overall, this multiphysics and multiscale framework provides a robust platform to investigate how atrial electrical alterations drive mechanical and hemodynamic alterations in both healthy and pathological conditions.

bioengineering↗

bioRxiv2023

Imaging the immune synapse: three-dimensional analysis of the immune synapse

T cell receptor (TCR) stimulation of T lymphocytes by antigen bound to the major histocompatibility complex (MHC) of an antigen-presenting cell (APC), together with the interaction of accessory molecules, induces the formation of the immunological synapse (IS), the convergence of secretion vesicles towards the centrosome, and the polarization of the centrosome to the IS. Upon IS formation, an initial increase in cortical filamentous actin (F-actin) at the IS takes place, followed by a decrease in F-actin density at the central region of the IS, which contains the secretory domain. These reversible, cortical actin cytoskeleton reorganization processes that characterize a mature IS occur during lytic granule secretion in cytotoxic T lymphocytes (CTL) and cytokine-containing vesicle secretion in T-helper (Th) lymphocytes. Besides, IS formation constitutes the basis of a signalling platform that integrates signals and coordinates molecular interactions that are necessary for an appropriate antigen-specific immune response. In this chapter we deal with the three-dimensional (3D) analysis of the synaptic interface architecture, as well as the analysis of the localization of different markers at the IS.

immunology↗

bioRxiv2022

Multiple Ciliary Localization Signals Control INPP5E Ciliary Targeting

Primary cilia are sensory membrane protrusions whose dysfunction causes diseases named ciliopathies. INPP5E is a ciliary phosphoinositide phosphatase mutated in ciliopathies like Joubert syndrome. INPP5E regulates numerous ciliary functions, such as cilium stability, trafficking, signaling, or exovesicle release. Despite its key ciliary roles, how INPP5E accumulates in cilia remains poorly understood. Herein, we show that INPP5E ciliary targeting requires its folded catalytic domain and is controlled by four ciliary localization signals (CLSs), the first two of which we newly discover: LLxPIR motif (CLS1), W383 (CLS2), FDRxLYL motif (CLS3) and CaaX box (CLS4). We answer two long-standing questions in the field. First, partial redundancy between CLS1 and CLS4 explains why CLS4 is dispensable for ciliary targeting. Second, the essential need for CLS2 on the catalytic domain surface clarifies why CLS3 and CLS4 are together insufficient for ciliary accumulation. Furthermore, we reveal that some Joubert syndrome mutations in INPP5E catalytic domain affect its ciliary targeting, and shed light on the mechanisms of action of each CLS. Thus, we find that CLS2 and CLS3 promote interaction with TULP3 and ARL13B, while downregulating CEP164 binding. On the other hand, CLS4 recruits PDE6D, RPGR and ARL13B, and cooperates with CLS1 in ATG16L1 binding. Lastly, we show INPP5E immune synapse targeting is CLS-independent. Altogether, we reveal unusual complexity in INPP5E ciliary targeting mechanisms, likely reflecting its multiple key roles in ciliary biology.

cell biology↗

bioRxiv2021

Analysis of centrosomal area actin reorganization and centrosome polarization upon lymphocyte activation at the immunological synapse

T cell receptor (TCR) and B cell receptor (BCR) stimulation of T and B lymphocytes, by antigen presented on an antigen-presenting cell (APC) induces the formation of the immunological synapse (IS). IS formation is associated with an initial increase in cortical filamentous actin (F-actin) at the IS, followed by a decrease in F-actin density at the central region of the IS, which contains the secretory domain. This is followed by the convergence of secretion vesicles towards the centrosome, and the polarization of the centrosome to the IS. These reversible, cortical actin cytoskeleton reorganization processes occur during lytic granule secretion in cytotoxic T lymphocytes (CTL) and natural killer (NK) cells, proteolytic granules secretion in B lymphocytes and during cytokine-containing vesicle secretion in T-helper (Th) lymphocytes. In addition, several findings obtained in T and B lymphocytes forming IS show that actin cytoskeleton reorganization also occurs at the centrosomal area. F-actin reduction at the centrosomal area appears to be associated with centrosome polarization. In this chapter we deal with the analysis of centrosomal area F-actin reorganization, as well as the centrosome polarization analysis towards the IS.

immunology↗

bioRxiv2020

Actin reorganization at the centrosomal area and the immune synapse regulates polarized secretory traffic of multivesicular bodies in T lymphocytes

T-cell receptor stimulation induces the convergence of multivesicular bodies towards the microtubule-organizing center (MTOC) and the polarization of the MTOC to the immune synapse (IS). These events lead to exosome secretion at the IS. We describe here that upon IS formation centrosomal area F-actin decreased concomitantly with MTOC polarization to the IS. PKC{delta}-interfered T cell clones showed a sustained level of centrosomal area F-actin associated with defective MTOC polarization. We analysed the contribution of two actin cytoskeleton-regulatory proteins, FMNL1 and paxillin, to the regulation of cortical and centrosomal F-actin networks. FMNL1{beta} phosphorylation and F-actin reorganization at the IS were inhibited in PKC{delta}-interfered clones. F-actin depletion at the central region of the IS, a requirement for MTOC polarization, was associated with FMNL1{beta} phosphorylation at its C-terminal, autoregulatory region. Interfering all FMNL1 isoforms prevented MTOC polarization; nonetheless, FMNL1{beta} re-expression restored MTOC polarization in a centrosomal area F-actin reorganization-independent manner. Moreover, PKC{delta}-interfered clones exhibited decreased paxillin phosphorylation at the MTOC, which suggests an alternative actin cytoskeleton regulatory pathway. Our results infer that PKC{delta} regulates MTOC polarization and secretory traffic leading to exosome secretion in a coordinated manner by means of two distinct pathways, one involving FMNL1{beta} regulation and controlling F-actin reorganization at the IS, and the other, comprising paxillin phosphorylation potentially controlling centrosomal area F-actin reorganization.

immunology↗