Estudio del papel funcional del ATP intravesicular en el almacenamiento y la exocitosis de catecolaminas

El ATP es transportado y co-almacenado junto a otros transmisores a altas concentraciones en probablemente todas las vesículas secretoras conocidas (Borges, 2013). En los gránulos cromafines, organelas similares a las vesículas grandes de núcleo denso (LDCV) presentes en neuronas y otras células neuroendocrinas, podría encontrarse en el orden de ¿120 mM (Kopell et al., 1982) frente a los ¿4 mM citosólicos, representanto alrededor de un 75% de la cantidad total celular (Corcoran et al., 1986). Al margen de su papel en la transmisión purinérgica, este nucleótido posee unas propiedades físico-químicas que lo hacen especial en el interior de las LCDVs y es la formación de complejos intravesiculares entre los tres componentes principales del gránulo: las catecolaminas (CA), las proteínas y el ATP (Kopell et al., 1982). Tales interacciones han sido postuladas durante muchos años para rendir cuenta a las altísimas concentraciones de las CA contenidas, entre 0,8-1 M (Montesinos et al., 2008; Albillos et al., 1997), y la estabilidad osmótica de los gránulos (Berneis, 1972; Weder and Wiegand, 1973). Todas las estrategias desarrolladas para la depleción del contenido intravesicular de nucleótidos sobre células vivas han resultado ser ineficaces. A diferencia de las CAs, cuyo contenido cuántico es fácilmente alterable por la concentración citosólica de dopamina, por ejemplo por la incubación de L-DOPA (Mosharov et al., 2003; Sombers et al., 2005; Omiatek et al., 2013; Diaz-Vera et al., 2012; Díaz-Vera et al., 2010; Montesinos et al., 2008), el ATP posee una baja tasa de recambio del ATP en las LDCVs (Corcoran et al., 1986) de forma que el contenido en purinas se opone a los cambios citosólicos que puedan ser inducidos por inhibidores del metabolismo energético, dificultando así el estudio de la falta de este componente intravesicular sobre la exocitosis, además de la vida de la célula. En este trabajo hemos empleado la interferencia de la expresión génica mediante siRNAs específicos del transportador de nucleótidos vesicular (VNUT) para explorar la repercusión sobre la acumulación y la exocitosis de CAs de las células cromafines bovinas. Las células interferidas con VNUT (VNUT-KD) exhibieron una reducción de más del 50% de la expresión del transportador, que se tradujo en una disminución de aproximadamente un 40% de ATP y adrenalina secretadas por vía exocitótica sin cambios en las CAs totales celulares ni en los incrementos de Ca2+ intracelular. El estudio de la liberación de CAs y el neuropéptido Y asociado a EGFP, expresado de forma heteróloga en un sistema a tiempo real, permitió atribuir esta disminución de la secreción a las vesículas de nueva síntesis afectadas por la carencia del VNUT, siendo las primeras en ser liberadas ante una estimulación nicotínica. Además, la incubación de las células con L-DOPA, produjo una secreción de dopamina mayor en las células control que en las VNUT-KD, datos que sugieren que los mecanismos de acumulación vesicular de CAs en células VNUT-KD son deficientes. Los registros amperométricos de las células VNUT-KD mostraron una reducción en más de dos veces la liberación de CAs en comparación con las células control. Esta diferencia no fue debida solamente a una reducción de más del 50% del contenido cuántico de CA sino que además contribuyó a un menor grado de reclutamiento de los gránulos afectados por la carencia de ATP, dada la disminución de frecuencia de eventos exocitóticos. Con estos datos llegamos a la conclusión de que el ATP intravesicular posee un papel regulador en la transmisión dada su implicación en la acumulación y la exocitosis de CAs

HIV-1 Nef Targets HDAC6 to Assure Viral Production and Virus Infection

HIV Nef is a central auxiliary protein in HIV infection and pathogenesis. Our results indicate that HDAC6 promotes the aggresome/autophagic degradation of the viral polyprotein Pr55Gag to inhibit HIV-1 production. Nef counteracts this antiviral activity of HDAC6 by inducing its degradation and subsequently stabilizing Pr55Gag and Vif viral proteins. Nef appears to neutralize HDAC6 by an acidic/endosomal-lysosomal processing and does not need the downregulation function, since data obtained with the non-associated cell-surface Nef-G2A mutant – the cytoplasmic location of HDAC6 – together with studies with chemical inhibitors and other Nef mutants, point to this direction. Hence, the polyproline rich region P72xxP75 (69–77 aa) and the di-Leucin motif in the Nef-ExxxLL160-165 sequence of Nef, appear to be responsible for HDAC6 clearance and, therefore, required for this novel Nef proviral function. Nef and Nef-G2A co-immunoprecipitate with HDAC6, whereas the Nef-PPAA mutant showed a reduced interaction with the anti-HIV-1 enzyme. Thus, the P72xxP75 motif appears to be responsible, directly or indirectly, for the interaction of Nef with HDAC6. Remarkably, by neutralizing HDAC6, Nef assures Pr55Gag location and aggregation at plasma membrane, as observed by TIRFM, promotes viral egress, and enhances the infectivity of viral particles. Consequently, our results suggest that HDAC6 acts as an anti-HIV-1 restriction factor, limiting viral production and infection by targeting Pr55Gag and Vif. This function is counteracted by functional HIV-1 Nef, in order to assure viral production and infection capacities. The interplay between HIV-1 Nef and cellular HDAC6 may determine viral infection and pathogenesis, representing both molecules as key targets to battling HIV

Contribution of the HIV-1 Envelope Glycoprotein to AIDS Pathogenesis and Clinical Progression

In the absence of antiviral therapy, HIV-1 infection progresses to a wide spectrum of clinical manifestations that are the result of an entangled contribution of host, immune and viral factors. The contribution of these factors is not completely established. Several investigations have described the involvement of the immune system in the viral control. In addition, distinct HLA-B alleles, HLA-B27, -B57-58, were associated with infection control. The combination of these elements and antiviral host restriction factors results in different clinical outcomes. The role of the viral proteins in HIV-1 infection has been, however, less investigated. We will review contributions dedicated to the pathogenesis of HIV-1 infection focusing on studies identifying the function of the viral envelope glycoprotein (Env) in the clinical progression because of its essential role in the initial events of the virus life-cycle. Some analysis showed that inefficient viral Envs were dominant in non-progressor individuals. These poorly-functional viral proteins resulted in lower cellular activation, viral replication and minor viral loads. This limited viral antigenic production allows a better immune response and a lower immune exhaustion. Thus, the properties of HIV-1 Env are significant in the clinical outcome of the HIV-1 infection and AIDS pathogenesis.This work was funded by the Spanish AIDS network “Red Temática Cooperativa de Investigación en SIDA” RD12/0017/0002, RD12/0017/0028, RD12/0017/0034, RD16/0025/0011, RDCIII16/0002/0005 and RD16/0025/0041 as part of the Plan Nacional R + D+I and co-funded by the Spanish “Instituto de Salud Carlos III (ISCIII)-Subdirección General de Evaluación y el Fondo Europeo de Desarrollo Regional (FEDER)”. J.B. is a researcher from “Fundació Institut de Recerca en Ciències de la Salut Germans Trias i Pujol” supported by the Health Department of the Catalonian Government/Generalitat de Catalunya and ISCIII grant Nos. PI17/01318 and PI20/00093 (to J.B.). Work in C.C. Lab was supported by grants SAF (2010-17226) and (2016-77894-R) from MINECO (Spain), FIS (PI13/02269, ISCIII) and PI20/00093. A.-V.F.’s Lab is supported by the European Regional Development Fund (ERDF), PID2021-123031OB-I00 (“Ministerio de Ciencia e Innovación”, Spain), RTI2018-093747-B-100 (“Ministerio de Ciencia, Innovación y Universidades”, Spain), ProID2020010093 (“Agencia Canaria de Investigación, Innovación y Sociedad de la Información” and the European Social Fund), UNLL10-3E-783 (ERDF and “Fundación CajaCanarias”) and “SEGAI-ULL”. S.-P.Y. is funded by “Fundación Doctor Manuel Morales” (La Palma, Spain) and “Contrato Pre-doctoral Ministerio-ULL Formación de Doctores” (2019 Program) (“Ministerio de Ciencia, Innovación y Universidades”, Spain). R.-C.R. is funded by RD16/0025/0011 and ProID2020010093 (“Agencia Canaria de Investigación, Innovación y Sociedad de la Información” and European Social Fund). J.-G.L. is funded by the “Juan de la Cierva de Incorporación” Spanish Program (IJC2019-038902-I) (“Ayudas Juan de la Cierva de incorporación; Agencia Estatal de Investigación. Ministerio de Ciencia e Innovación”).S

The Characteristics of the HIV-1 Env Glycoprotein Are Linked With Viral Pathogenesis

The understanding of HIV-1 pathogenesis and clinical progression is incomplete due to the variable contribution of host, immune, and viral factors. The involvement of viral factors has been investigated in extreme clinical phenotypes from rapid progressors to long-term non-progressors (LTNPs). Among HIV-1 proteins, the envelope glycoprotein complex (Env) has been concentrated on in many studies for its important role in the immune response and in the first steps of viral replication. In this study, we analyzed the contribution of 41 Envs from 24 patients with different clinical progression rates and viral loads (VLs), LTNP-Elite Controllers (LTNP-ECs); Viremic LTNPs (vLTNPs), and non-controller individuals contemporary to LTNPs or recent, named Old and Modern progressors. We studied the Env expression, the fusion and cell-to-cell transfer capacities, as well as viral infectivity. The sequence and phylogenetic analysis of Envs were also performed. In every functional characteristic, the Envs from subjects with viral control (LTNP-ECs and vLTNPs) showed significant lower performance compared to those from the progressor individuals (Old and Modern). Regarding sequence analysis, the variable loops of the gp120 subunit of the Env (i.e., V2, V4, and mainly V5) of the progressor individuals showed longer and more glycosylated sequences than controller subjects. Therefore, HIV-1 Envs from virus of patients presenting viremic control and the non-progressor clinical phenotype showed poor viral functions and shorter sequences, whereas functional Envs were associated with virus of patients lacking virological control and with progressor clinical phenotypes. These correlations support the role of Env genotypic and phenotypic characteristics in the in vivo HIV-1 infection and pathogenesis.This work is supported by Spanish AIDS network “Red Temática Cooperativa de Investigación en SIDA” RD12/0017/0002, RD12/0017/0028, RD12/0017/0034, RD16/0025/0011, RDCIII16/0002/0005, and RD16/0025/0041 as part of the Plan Nacional R + D + I and cofunded by Spanish “Instituto de Salud Carlos III (ISCIII)-Subdirección General de Evaluación y el Fondo Europeo de Desarrollo Regional (FEDER).” JB is a researcher from “Fundació Institut de Recerca en Ciències de la Salut Germans Trias i Pujol” supported by the Health Department of the Catalan Government/Generalitat de Catalunya and ISCIII grant numbers PI17/01318 and PI20/00093 (to JB). Work in CL-G and CC lab was supported by grants SAF (2010-17226) and (2016-77894-R) from MINECO (Spain) and FIS (PI 13/02269 and PI20/00093, ISCIII). AV-F’s Lab is supported by the European Regional Development Fund (ERDF), RTI2018-093747-B-100 (“Ministerio de Ciencia e Innovación,” Spain), “Ministerio de Ciencia, Innovación y Universidades” (Spain), ProID2020010093 (“Agencia Canaria de Investigación, Innovación y Sociedad de la Información” and European Social Fund), UNLL10-3E-783 (ERDF and “Fundación CajaCanarias”) and “SEGAI-ULL.” SP-Y is funded by “Fundación Doctor Manuel Morales” (La Palma, Spain) and “Contrato Predoctoral Ministerio-ULL Formación de Doctores” (2019 Program; “Ministerio de Ciencia, Innovación y Universidades,” Spain). RC-R is funded by RD16/0025/0011 and ProID2020010093 (“Agencia Canaria de Investigación, Innovación y Sociedad de la Información” and European Social Fund). JE-H is funded by the Cabildo Tenerife “Agustin de Betancourt” 2017 Program.S

Transactive Response DNA-Binding Protein (TARDBP/TDP-43) Regulates Cell Permissivity to HIV-1 Infection by Acting on HDAC6

The transactive response DNA-binding protein (TARDBP/TDP-43) influences the processing of diverse transcripts, including that of histone deacetylase 6 (HDAC6). Here, we assessed TDP-43 activity in terms of regulating CD4+ T-cell permissivity to HIV-1 infection. We observed that overexpression of wt-TDP-43 increased both mRNA and protein levels of HDAC6, resulting in impaired HIV-1 infection independently of the viral envelope glycoprotein complex (Env) tropism. Consistently, using an HIV-1 Env-mediated cell-to-cell fusion model, the overexpression of TDP-43 levels negatively affected viral Env fusion capacity. Silencing of endogenous TDP-43 significantly decreased HDAC6 levels and increased the fusogenic and infection activities of the HIV-1 Env. Using pseudovirus bearing primary viral Envs from HIV-1 individuals, overexpression of wt-TDP-43 strongly reduced the infection activity of Envs from viremic non-progressors (VNP) and rapid progressors (RP) patients down to the levels of the inefficient HIV-1 Envs observed in long-term non-progressor elite controllers (LTNP-EC). On the contrary, silencing endogenous TDP-43 significantly favored the infectivity of primary Envs from VNP and RP individuals, and notably increased the infection of those from LTNP-EC. Taken together, our results indicate that TDP-43 shapes cell permissivity to HIV-1 infection, affecting viral Env fusion and infection capacities by altering the HDAC6 levels and associated tubulin-deacetylase anti-HIV-1 activity.This work is supported by the Spanish AIDS network “Red Temática Cooperativa de Investigación en SIDA” RD12/0017/0002, RD12/0017/0028, RD12/0017/0034, RD16/0025/0011, RDCIII16/0002/0005 and RD16/0025/0041 as part of the Plan Nacional R + D+I and co-funded by the Spanish “Instituto de Salud Carlos III (ISCIII)-Subdirección General de Evaluación y el Fondo Europeo de Desarrollo Regional (FEDER)”. J.B. is a researcher from “Fundació Institut de Recerca en Ciències de la Salut Germans Trias i Pujol” supported by the Health Department of the Catalonian Government/Generalitat de Catalunya and ISCIII grant numbers PI17/01318 and PI20/00093 (to J.B.). Work in CC Lab was supported by grants SAF (2010-17226) and (2016-77894-R) from MINECO (Spain), FIS (PI 13/02269, ISCIII) and PI20/00093. Work in CF Lab was supported by the Cabildo Insular de Tenerife (grants CGIEU0000219140 and “Apuestas científicas del ITER para colaborar en la lucha contra la COVID-19”); the agreement with the Instituto Tecnológico y de Energías Renovables (ITER) to strengthen scientific and technological education, training research, development and innovation in Genomics, Personalized Medicine and Biotechnology (grant number OA17/008). A.V.-F.’s Lab is supported by the European Regional Development Fund (ERDF), RTI2018-093747-B-100 (“Ministerio de Ciencia e Innovación”, Spain), “Ministerio de Ciencia, Innovación y Universidades” (Spain), ProID2020010093 (“Agencia Canaria de Investigación, Innovación y Sociedad de la Información” and European Social Fund), UNLL10-3E-783 (ERDF and “Fundación CajaCanarias”) and “SEGAI-ULL”. S.P-Y is funded by “Fundación Doctor Manuel Morales” (La Palma, Spain) and “Contrato Predoctoral Ministerio-ULL Formación de Doctores” (2019 Program) (“Ministerio de Ciencia, Innovación y Universidades”, Spain). R.C.-R. is funded by RD16/0025/0011 and ProID2020010093 (“Agencia Canaria de Investigación, Innovación y Sociedad de la Información” and European Social Fund). J.G.-L. is funded by the “Juan de la Cierva de Incorporación” Spanish Program (IJC2019-038902-I) (“Ayudas Juan de la Cierva de incorporación; Agencia Estatal de Investigación. Ministerio de Ciencia e Innovación”).S

HIV-1 envelope glycoproteins isolated from viremic non-progressor individuals are fully functional and cytopathic

International audienc

TDP-43 Controls HIV-1 Viral Production and Virus Infectiveness

The transactive response DNA-binding protein (TARDBP/TDP-43) is known to stabilize the anti-HIV-1 factor, histone deacetylase 6 (HDAC6). TDP-43 has been reported to determine cell permissivity to HIV-1 fusion and infection acting on tubulin-deacetylase HDAC6. Here, we studied the functional involvement of TDP-43 in the late stages of the HIV-1 viral cycle. The overexpression of TDP-43, in virus-producing cells, stabilized HDAC6 (i.e., mRNA and protein) and triggered the autophagic clearance of HIV-1 Pr55Gag and Vif proteins. These events inhibited viral particle production and impaired virion infectiveness, observing a reduction in the amount of Pr55Gag and Vif proteins incorporated into virions. A nuclear localization signal (NLS)-TDP-43 mutant was not able to control HIV-1 viral production and infection. Likewise, specific TDP-43-knockdown reduced HDAC6 expression (i.e., mRNA and protein) and increased the expression level of HIV-1 Vif and Pr55Gag proteins and α-tubulin acetylation. Thus, TDP-43 silencing favored virion production and enhanced virus infectious capacity, thereby increasing the amount of Vif and Pr55Gag proteins incorporated into virions. Noteworthy, there was a direct relationship between the content of Vif and Pr55Gag proteins in virions and their infection capacity. Therefore, for TDP-43, the TDP-43/HDAC6 axis could be considered a key factor to control HIV-1 viral production and virus infectiveness

Zika Virus Pathogenesis: A Battle for Immune Evasion

Zika virus (ZIKV) infection and its associated congenital and other neurological disorders, particularly microcephaly and other fetal developmental abnormalities, constitute a World Health Organization (WHO) Zika Virus Research Agenda within the WHO’s R&D Blueprint for Action to Prevent Epidemics, and continue to be a Public Health Emergency of International Concern (PHEIC) today. ZIKV pathogenicity is initiated by viral infection and propagation across multiple placental and fetal tissue barriers, and is critically strengthened by subverting host immunity. ZIKV immune evasion involves viral non-structural proteins, genomic and non-coding RNA and microRNA (miRNA) to modulate interferon (IFN) signaling and production, interfering with intracellular signal pathways and autophagy, and promoting cellular environment changes together with secretion of cellular components to escape innate and adaptive immunity and further infect privileged immune organs/tissues such as the placenta and eyes. This review includes a description of recent advances in the understanding of the mechanisms underlying ZIKV immune modulation and evasion that strongly condition viral pathogenesis, which would certainly contribute to the development of anti-ZIKV strategies, drugs, and vaccines.Depto. de Genética, Fisiología y MicrobiologíaFac. de Ciencias BiológicasTRUEpu

Chalcones as positive allosteric modulators of α7 nicotinic acetylcholine receptors: A new target for a privileged structure

The α7 acetylcholine nicotine receptor is a ligand-gated ion channel that is involved in cognition disorders, schizophrenia, pain and inflammation among other diseases. Therefore, the development of new agents that target this receptor has great significance. Positive allosteric modulators might be advantageous, since they facilitate receptor responses without directly interacting with the agonist binding site. Here we report the search for and further design of new positive allosteric modulators having the relatively simple chalcone structure. From the natural product isoliquiritigenin as starting point, chalcones substituted with hydroxyl groups at defined locations were identified as optimal and specific promoters of α77 nicotinic function. The most potent compound (2,4,2-2,5-2-tetrahydroxychalcone, 111) was further characterized showing its potential as neuroprotective, analgesic and cognitive enhancer, opening the way for future developments around the chalcone structure.Peer Reviewe