Biology subjects

Garaigorta, U.

Publications and source records attributed to Garaigorta, U..

5 recordsLinked to original sources

bioRxiv2025

HIV-1 Envelope glycoprotein modulates CXCR4 clustering and dynamics on the T cell membrane

HIV-1 entry into susceptible cells requires the dynamic interaction of its envelope (Env) glycoprotein with the host cell receptor CD4 and a co-receptor, either CCR5 or CXCR4. While the core molecular mechanisms driving Env-receptor interactions and subsequent membrane fusion are well characterized, the precise nanoscale spatial reorganization of these co-receptors at the viral binding site remains poorly defined. In this study, we employed single-particle tracking total internal reflection fluorescence (SPT-TIRF) microscopy to quantitatively analyze nanoscale organizational changes of CXCR4 on the surface of CD4+ T cells following binding by X4-tropic HIV-1. Our data reveal that both recombinant X4-gp120 and virus-like particles expressing physiological levels of X4 Env proteins (gp120 and gp41) promote CXCR4 clustering, a phenomenon linked to cell infection. Furthermore, these ligands induced oligomerization of CXCR4R334X, a naturally occurring mutant associated with WHIM syndrome that supports HIV-1 infection but fails to oligomerize in response to CXCL12. Our findings establish a link between CXCR4 clustering and HIV-1 infection, enhancing our understanding of the initial events in viral attachment and entry. These results further suggest that HIV-1 depends on a specific spatial arrangement of co-receptors, distinct from that induced by their natural chemokine ligands, highlighting the critical role of cell-surface receptor spatial organization in dictating cellular function.

immunology↗

bioRxiv2024

Time-based quantitative proteomic and phosphoproteomic analysis of A549-ACE2 cells during SARS-CoV-2 infection

The outbreak of COVID-19, a disease caused by severe acute respiratory syndrome coronavirus 2, led to an ongoing pandemic with devastating consequences for the global economy and human health. With the global spread of SARS-CoV-2, multidisciplinary initiatives were launched to explore new diagnostic, therapeutic, and vaccination strategies. From this perspective, proteomics could help to understand the mechanisms associated with SARS-CoV-2 infection and to identify new therapeutic targets for antiviral drug repurposing and/or discovery. A TMT-based quantitative proteomics and phosphoproteomics analysis was performed to study the proteome remodeling of human lung alveolar cells transduced to express human ACE2 (A549-ACE2) after infection with SARS-CoV-2. Targeted PRM analysis was performed to assess the detectability in serum and prognostic value of selected proteins. A total of 6802 proteins and 6428 phospho-sites were identified in A549-ACE2 cells after infection with SARS-CoV-2. Regarding the viral proteome, 8 proteins were differentially expressed after 6 h of infection and reached a steady state after 9 h. In addition, we detected several phosphorylation sites of SARS-CoV-2 proteins, including two novel phosphorylation events at S410 and S416 of the viral nucleoprotein. ImportanceThe differential proteins here identified revealed that A549-ACE2 cells undergo a time-dependent regulation of essential processes, delineating the precise intervention of the cellular machinery by the viral proteins. From this mechanistic background and by applying machine learning modelling, 29 differential proteins were selected and detected in the serum of COVID-19 patients, 14 of which showed promising prognostic capacity. Targeting these proteins and the protein kinases responsible for the reported phosphorylation changes may provide efficient alternative strategies for the clinical management of COVID-19.

biochemistry↗

bioRxiv2021

SARS-CoV-2 fears green: the chlorophyll catabolite Pheophorbide a is a potent antiviral

SARS-CoV-2 pandemic is having devastating consequences worldwide. Although vaccination advances at good pace, effectiveness against emerging variants is unpredictable. The virus has displayed a remarkable resistance to treatments and no drugs have been proved fully effective against Covid-19. Thus, despite the international efforts, there is still an urgent need for new potent and safe antivirals against SARS-CoV-2. Here we exploited the enormous potential of plant metabolism using the bryophyte Marchantia polymorpha and identified a potent SARS-CoV-2 antiviral, following a bioactivity-guided fractionation and mass-spectrometry approach. We found that the chlorophyll derivative Pheophorbide a (PheoA), a porphyrin compound similar to animal Protoporphyrin IX, has an extraordinary antiviral activity against SARS-CoV-2 preventing infection of cultured monkey and human cells, without noticeable cytotoxicity. We also show that PheoA prevents coronavirus entry into the cells by directly targeting the viral particle. Besides SARS-CoV-2, PheoA also displayed a broad-spectrum antiviral activity against (+) strand RNA viral pathogens such as HCV, West Nile, and other coronaviruses, but not against (-) strand RNA viruses, such as VSV. Our results indicate that PheoA displays a remarkable potency and a satisfactory therapeutic index, which together with its previous use in photoactivable cancer therapy in humans, suggest that it may be considered as a potential candidate for antiviral therapy against SARS-CoV-2.

molecular biology↗

bioRxiv2021

Aberrant integration of Hepatitis B virus DNA promotes major restructuring of human hepatocellular carcinoma genome architecture

Most cancers are characterized by the somatic acquisition of genomic rearrangements during tumour evolution that eventually drive the oncogenesis. There are different mutational mechanisms causing structural variation, some of which are specific to particular cancer types. Here, using multiplatform sequencing technologies, we identify and characterize a remarkable mutational mechanism in human hepatocellular carcinoma caused by Hepatitis B virus, by which DNA molecules from the virus are inserted into the tumour genome causing dramatic changes in its configuration, including non-homologous chromosomal fusions and megabase-size telomeric deletions. This aberrant mutational process, present in at least 8% of all HCC tumours, is active early during liver cancer evolution and can provide the driver rearrangements that a cancer clone requires to survive and grow.

cancer biology↗

bioRxiv2020

Host-directed FDA-approved drugs with antiviral activity against SARS-CoV-2 identified by hierarchical in silico/in vitro screening methods

The unprecedent situation generated by the COVID-19 global emergency prompted us to actively work to fight against this pandemic by searching for repurposable agents among FDA approved drugs to shed light into immediate opportunities for the treatment of COVID-19 patients. In the attempt to proceed toward a proper rationalization of the search for new antivirals among approved drugs, we carried out a hierarchical in silico/in vitro protocol which successfully combines virtual and biological screening to speed up the identification of host-directed therapies against COVID-19 in an effective way. To this end a multi-target virtual screening approach focused on host-based targets related to viral entry followed by the experimental evaluation of the antiviral activity of selected compounds has been carried out. As a result, five different potentially repurposable drugs interfering with viral entry, cepharantine, clofazimine, metergoline, imatinib and efloxate, have been identified.

microbiology↗