Biology subjects

Pardo, L.

Publications and source records attributed to Pardo, L..

7 recordsLinked to original sources

bioRxiv2024

Metabolic adaptations of micrometastases alter EV production to generate invasive microenvironments

Altered cellular metabolism has been associated with acquisition of invasive phenotypes during metastasis. To study this, we combined a genetically engineered mouse model of mammary carcinoma with syngeneic transplantation and primary tumour resection to generate isogenic cells from primary tumours and their corresponding lung micrometastases. Metabolic analyses indicated that micrometastatic cells increase proline production at the expense of glutathione synthesis leading to a reduction in total glutathione levels. Micrometastatic cells also have altered sphingomyelin metabolism leading to increased intracellular levels of specific ceramides. The combination of these two metabolic adaptations alters small extracellular vesicle (sEV) production to drive generation of an invasive microenvironment. Indeed, micrometastatic cells shut-down Rab27-dependent production of sEVs and, instead, switch-on neutral sphingomyelinase-2 (nSM2)-dependent sEV release. sEVs released in a nSM2-dependent manner from micrometastatic cells, in turn, influence the ability of fibroblasts to deposit extracellular matrix which promotes cancer cell invasiveness. These data provide evidence that metabolic rewiring drives invasive processes in metastasis by influencing sEV release. SummaryBreast cancer cells isolated from lung micrometastases have altered metabolism which influences extracellular vesicle production to generate invasive microenvironments.

cancer biology↗

bioRxiv2024

Homodimerization of CB2 cannabinoid receptor triggered by a bivalent ligand enhances cellular signaling

G protein-coupled receptors (GPCRs) exist within a landscape of interconvertible conformational states and in dynamic equilibrium between monomers and higher-order oligomers, both influenced by ligand binding. Here, we have shown that a homobivalent ligand formed by equal chromenopyrazole moieties as pharmacophores, connected by 14 methylene units, can modulate the dynamics of the cannabinoid CB2 receptor (CB2R) homodimerization by simultaneously binding both protomers of the CB2R-CB2R homodimer. Computational and pharmacological experimentals showed that one of the ligand pharmacophores binds to the orthosteric site of one protomer, and the other pharmacophore to a membrane-oriented pocket between transmembranes 1 and 7 of the partner protomer. This provides unique pharmacological properties, such as increased potency in Gi binding and increased recruitment of {beta}-arrestin. Thus, by modulating dimerization dynamics, it may be possible to fine-tune CB2R activity with potentially improved therapeutic outcomes. HIGHLIGHTSO_LIA homobivalent ligand of CB2R (PM369) modulates the dynamics of receptor homodimerization C_LIO_LIPM369 binds to the orthosteric site of one protomer and to a complementary, membrane-facing, site of the other protomer C_LIO_LIPM369 triggers CB2R homodimerization via the TM 1/7 interface that provides unique pharmacological properties C_LIO_LIPM369 potentiates signaling, increased potency in Gi binding and increased recruitment of {beta}-arrestin C_LIO_LIThese results highlight new approaches to control GPCR signaling C_LI GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=122 SRC="FIGDIR/small/593612v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@1736aeborg.highwire.dtl.DTLVardef@707654org.highwire.dtl.DTLVardef@168925borg.highwire.dtl.DTLVardef@60bc11_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2023

Structural basis for constitutive activation and CXCL1 recognition of human herpesvirus 8-encoded G protein-coupled receptor KSHV-GPCR

Kaposis sarcoma-associated herpesvirus (KSHV) encodes a viral G protein-coupled receptor, KSHV-GPCR, that contributes to KSHV immune evasion and pathogenesis of Kaposis Sarcoma. KSHV-GPCR shares a high similarity with CXC chemokine receptors CXCR2 and can be activated by selected chemokine ligands. KSHV-GPCR is also unique for its constitutive activity by coupling to various G proteins. We investigated the structural basis of ligand-dependent as well as constitutive activity of KSHV-GPCR through cryo-EM structural determination of KSHV-GPCR-Gi signaling complexes with and without bound CXCL1 chemokine ligand. Analysis of the apo-KSHV-GPCR-Gi structure, with an overall resolution of 2.81 [A], unraveled the involvement of extracellular loop 2 in constitutive activation of the receptor. This and other structural motifs serve to stabilize the constitutively-active KSHV-GPCR. The CXCL1-bound KSHV-GPCR-Gi structure was solved to an overall resolution of 3.01 [A], and showed a two-site binding of the chemokine by the receptor. Together with functional validations, this work shed light on the structural basis for constitutive as well as CXCL1-induced activation of KSHV-GPCR. The work also demonstrates evolutionary advantage in immune evasion by KSHV through its virally encoded chemokine receptor, with potential implications in developing therapeutic strategies for KSHV infection.

immunology↗

bioRxiv2023

The eIF4A2 negative regulator of mRNA translation promotes extracellular matrix deposition to accelerate hepatocellular carcinoma initiation

Increased protein synthesis supports growth of established tumours. However, how mRNA translation contributes to early tumorigenesis remains unclear. Here we show that following oncogene activation, hepatocytes enter a non-proliferative/senescent-like phase characterized by 5{beta}1 integrin-dependent deposition of fibronectin-rich extracellular matrix (ECM) niches. These niches then promote exit from oncogene-induced senescence to permit progression to proliferating hepatocellular carcinoma (HCC). Removal of eIF4A2, a negative regulator of mRNA translation, boosts the synthesis of membrane/secretory proteins which drives a compensatory increase in the turnover/degradation of membrane proteins including 5{beta}1 integrin. This increased membrane protein degradation, in turn, compromises generation of ECM-rich tumour initiation niches, senescence-exit and progression to proliferating HCC. Consistently, pharmacological inhibition of mRNA translation following eIF4A2 loss restores ECM deposition and reinstates HCC progression. Thus, although inhibition of protein synthesis may be an effective way to reduce tumour biomass and the growth of established tumours, our results highlight how agents which reduce mRNA translation, if administered during early tumorigenesis, may awaken senescent cells and promote tumour progression.

cancer biology↗

bioRxiv2022

Defective neuritogenesis in Abcd1/2 deficient rat neurons due to intrinsic and astrocyte-dependent mechanisms

X-linked adrenoleukodystrophy (X-ALD) is a rare neurometabolic and demyelinating disorder caused by loss of function mutations of the ABCD1 transporter that imports very-long-chain fatty acids (VLCFA) into the peroxisome for beta-oxidation. Impaired ABCD1 function results in VLCFA accumulation, which ultimately causes lethal forms of X-ALD in children (CCALD) and adults (CAMN). Because X-ALD is a genetic disorder, we looked for signs of altered neurodevelopmental pathways in the transcriptomes of brain cortical tissues free of pathology from patients that died of CALD or CAMN. Several categories related to brain development, axonal growth, synaptic signaling and synaptic compartments were significantly dysregulated in both CALD and CAMN, suggesting that congenital circuit abnormalities might be structural in brains of mutated ABCD1 carriers. We partially dissected the cellular origin of dysregulated pathways using rat neuronal and astrocytic cultures in which X-ALD was modeled by silencing of Abcd1 and Abcd2 by RNA interference. Abcd2 was silenced lest it compensated for Abcd1 loss. Abcd1/2 deficient neurons presented higher rates of death, reduced sizes and defective formation of spines, dendrites and axons. The aberrant neuron development was caused by cell-autonomous and astrocyte-dependent mechanisms, and involved Wnt signaling, as suggested by the rescue of the expression of a synaptic gene upon pharmacological activation of the Wnt pathway. As recently proposed for neurogenetic disorders such as Huntingtons disease, our data suggest that X-ALD has a neurodevelopmental component that may cause psychiatric alterations and prime neural circuits for neurodegeneration. If this is the case, therapies aimed at restoring neural-circuit function in neurodevelopmental disorders may be reprofiled for X-ALD therapeutics.

neuroscience↗

bioRxiv2020

The mutational landscape of human olfactory G protein-coupled receptors

Olfactory receptors (ORs) constitute a large family of sensory proteins that enable us to recognize a wide range of chemical volatiles in the environment. By contrast to the extensive information about human olfactory thresholds for thousands of odorants, studies of the genetic influence on olfaction are limited to a few examples. Here, we analyzed a compendium of 118,057 natural variants in human ORs collected from the public domain. OR mutations were categorized depending on their genomic and protein contexts, as well as their frequency of occurrence in several human populations. Functional interpretation of the natural changes was estimated from the increasing knowledge of the structure and function of the G protein-coupled receptor (GPCR) family, to which ORs belong. Our analysis reveals an extraordinary diversity of natural variations in the olfactory gene repertoire between individuals and populations, with a significant number of changes occurring at structural conserved regions. A particular attention is paid to mutations in positions linked to the conserved GPCR activation mechanism that could imply phenotypic variation in the olfactory perception. An interactive web application (available at http://lmc.uab.cat/hORMdb) was developed for the management and visualization of this mutational dataset.

bioinformatics↗

bioRxiv2018

Genomic epidemiology supports multiple introductions and cryptic transmission of Zika virus in Colombia

BackgroundColombia was the second most affected country during the American Zika virus (ZIKV) epidemic, with over 109,000 reported cases. Despite the scale of the outbreak, limited genomic sequence data were available from Colombia. We sought to sequence additional samples and use genomic epidemiology to describe ZIKV dynamics in Colombia.\n\nMethodsWe sequenced ZIKV genomes directly from clinical diagnostic specimens and infected Aedes ae-gypti samples selected to cover the temporal and geographic breadth of the Colombian outbreak. We performed phylogeographic analysis of these genomes, along with other publicly-available ZIKV genomes from the Americas, to estimate the frequency and timing of ZIKV introductions to Colombia.\n\nResultsWe attempted PCR amplification on 184 samples; 19 samples amplified sufficiently to perform sequencing. Of these, 8 samples yielded sequences with at least 50% coverage. Our phylogeo-graphic reconstruction indicates two separate introductions of ZIKV to Colombia, one of which was previously unrecognized. We find that ZIKV was first introduced to Colombia in February 2015 (95%CI: Jan 2015 - Apr 2015), corresponding to 5 to 8 months of cryptic ZIKV transmission prior to confirmation in September 2015. Despite the presence of multiple introductions, we find that the majority of Colombian ZIKV diversity descends from a single introduction. We find evidence for movement of ZIKV from Colombia into bordering countries, including Peru, Ecuador, Panama, and Venezuela.\n\nConclusionsSimilarly to genomic epidemiologic studies of ZIKV dynamics in other countries, we find that ZIKV circulated cryptically in Colombia. This more accurate dating of when ZIKV was circulating refines our definition of the population at risk. Additionally, our finding that the majority of ZIKV transmission within Colombia was attributable to transmission between individuals, rather than repeated travel-related importations, indicates that improved detection and control might have succeeded in limiting the scale of the outbreak within Colombia.

genomics↗