SUMOylation regulates LKB1 localization and its oncogenic activity in liver cancer

BACKGROUND: Even though liver kinase B1 (LKB1) is usually described as a tumor suppressor in a wide variety of tissues, it has been shown that LKB1 aberrant expression is associated with bad prognosis in Hepatocellular Carcinoma (HCC). METHODS: Herein we have overexpressed LKB1 in human hepatoma cells and by using histidine pull-down assay we have investigated the role of the hypoxia-related post-translational modification of Small Ubiquitin-related Modifier (SUMO)ylation in the regulation of LKB1 oncogenic role. Molecular modelling between LKB1 and its interactors, involved in regulation of LKB1 nucleocytoplasmic shuttling and LKB1 activity, was performed. Finally, high affinity SUMO binding entities-based technology were used to validate our findings in a pre-clinical mouse model and in clinical HCC. FINDINGS: We found that in human hepatoma cells under hypoxic stress, LKB1 overexpression increases cell viability and aggressiveness in association with changes in LKB1 cellular localization. Moreover, by using site-directed mutagenesis, we have shown that LKB1 is SUMOylated by SUMO-2 at Lys178 hampering LKB1 nucleocytoplasmic shuttling and fueling hepatoma cell growth. Molecular modelling of SUMO modified LKB1 further confirmed steric impedance between SUMOylated LKB1 and the STe20-Related ADaptor cofactor (STRADα), involved in LKB1 export from the nucleus. Finally, we provide evidence that endogenous LKB1 is modified by SUMO in pre-clinical mouse models of HCC and clinical HCC, where LKB1 SUMOylation is higher in fast growing tumors. INTERPRETATION: Overall, SUMO-2 modification of LKB1 at Lys178 mediates LKB1 cellular localization and its oncogenic role in liver cancer. FUND: This work was supported by grants from NIH (US Department of Health and Human services)-R01AR001576-11A1 (J.M.M and M.L.M-C.), Gobierno Vasco-Departamento de Salud 2013111114 (to M.L.M.-C), ELKARTEK 2016, Departamento de Industria del Gobierno Vasco (to M.L.M.-C), MINECO: SAF2017-87301-R and SAF2014-52097-R integrado en el Plan Estatal de Investigación Cientifica y Técnica y Innovación 2013-2016 cofinanciado con Fondos FEDER (to M.L.M.-C and J.M.M., respectively), BFU2015-71017/BMC MINECO/FEDER, EU (to A.D.Q. and I.D.M.), BIOEF (Basque Foundation for Innovation and Health Research): EITB Maratoia BIO15/CA/014; Instituto de Salud Carlos III:PIE14/00031, integrado en el Plan Estatal de Investigación Cientifica y Técnica y Innovacion 2013-2016 cofinanciado con Fondos FEDER (to M.L.M.-C and J.M.M), Asociación Española contra el Cáncer (T.C.D, P·F-T and M.L.M-C), Daniel Alagille award from EASL (to T.C.D), Fundación Científica de la Asociación Española Contra el Cancer (AECC Scientific Foundation) Rare Tumor Calls 2017 (to M.L.M and M.A), La Caixa Foundation Program (to M.L.M), Programma di Ricerca Regione-Università 2007-2009 and 2011-2012, Regione Emilia-Romagna (to E.V.), Ramón Areces Foundation and the Andalusian Government (BIO-198) (A.D.Q. and I.D.M.), ayudas para apoyar grupos de investigación del sistema Universitario Vasco IT971-16 (P.A.), MINECO:SAF2015-64352-R (P.A.), Institut National du Cancer, FRANCE, INCa grant PLBIO16-251 (M.S.R.), MINECO - BFU2016-76872-R to (E.B.). Work produced with the support of a 2017 Leonardo Grant for Researchers and Cultural Creators, BBVA Foundation (M.V-R). Finally, Ciberehd_ISCIII_MINECO is funded by the Instituto de Salud Carlos III. We thank MINECO for the Severo Ochoa Excellence Accreditation to CIC bioGUNE (SEV-2016-0644). Funding sources had no involvement in study design; in the collection, analysis, and interpretation of data; in the writing of the report; and in the decision to submit the paper for publication

HuR biological function involves RRM3-mediated dimerization and RNA binding by all three RRMs

HuR/ELAVL1 is an RNA-binding protein involved in differentiation and stress response that acts primarily by stabilizing messenger RNA (mRNA) targets. HuR comprises three RNA recognition motifs (RRMs) where the structure and RNA binding of RRM3 and of full-length HuR remain poorly understood. Here, we report crystal structures of RRM3 free and bound to cognate RNAs. Our structural, NMR and biochemical data show that RRM3 mediates canonical RNA interactions and reveal molecular details of a dimerization interface localized on the α-helical face of RRM3. NMR and SAXS analyses indicate that the three RRMs in full-length HuR are flexibly connected in the absence of RNA, while they adopt a more compact arrangement when bound to RNA. Based on these data and crystal structures of tandem RRM1,2-RNA and our RRM3-RNA complexes, we present a structural model of RNA recognition involving all three RRM domains of full-length HuR. Mutational analysis demonstrates that RRM3 dimerization and RNA binding is required for functional activity of full-length HuR in vitro and to regulate target mRNAs levels in human cells, thus providing a fine-tuning for HuR activity in vivo.España, MINECO BFU2015-71017España, Junta de Andalucía CVI-BIO198; P11-CVI7216 to I.D.M

Dimerization model of the C-terminal RNA Recognition Motif of HuR

In PressHuman antigen R (HuR) is a ubiquitous 32kDa protein comprising three RNA Recognition Motifs (RRMs), whose main function is to bind Adenylate and uridylate Rich Elements (AREs) in 3′ UnTranslated Regions (UTRs) of mRNAs. In addition to binding RNA molecules, the third domain (RRM3) is involved in HuR oligomerization and apoptotic signaling. The RRM3 monomer is able to dimerize, with its self-binding affinity being dependent on ionic strength. Here we provide a deeper structural insight into the nature of the encounter complexes leading to the formation of RRM3 dimers by using Brownian Dynamics and Molecular Dynamics. Our computational data show that the initial unspecific encounter follows a downhill pathway until reaching an optimum conformation stabilized by hydrophobic interactions.I.D.-M. wishes to thank the Andalusian Government (P07-CVI-02896, P11-CVI-07216 and BIO198) for financial support.Peer reviewe

August Pi i Sunyer (1879-1965) : una figura a recuperar para la historia de la escuela psicológica de Barcelona

El desarrollo histórico de la escuela psicológica de Barcelona se inicia con la labor de investigación científica llevada a cabo por Ramón Turró -considerado el padre de la psicología experimental catalana- y se extiende hasta la obra de personajes de la relevancia de Emilio Mira i López -artífice de la consolidación de la psicología aplicada en España. Justo en el centro de esta línea evolutiva, se sitúa la figura de August Pi i Sunyer. Discípulo y colaborador de R. Turró, se convierte, al mismo tiempo, en maestro inspirador de E. Mira. En el presente artículo se muestran las coordenadas biográficas, así como las claves teóricas, que nos permiten ubicar a August Pi i Sunyer en el entramado del surgimiento de la psicología experimental catalana, a través de su implicación en la escuela psicológica de BarcelonaThe historical development of the psychological school of Barcelona begins with the scientific research conducted by Ramon Turro -considered the father of Catalan experimental psychology- and extends to the work of leading figures such as Emilio Mira i Lopez -architect of the consolidation of applied psychology in Spain. Right in the middle of this evolutionary line, is located the figure of August Pi i Sunyer. Disciple and collaborator of R. Turro, becomes, at the same time, in inspiring master of E. Mira. This article shows the biographical coordinates, as well as the theoretical keys, that allow us to situate August Pi i Sunyer in the framework of the emergence of catalane experimental psychology, through their involvement in psychological school of Barcelona

Las redes de comunicación para el aprendizaje y la formación docente universitaria

La actual sociedad del conocimiento está demandando un profesorado que sepa trabajar con las tecnologías de la información y la comunicación además de saber hacerlo de forma colaborativa. Desde este artículo esbozamos razones para que este tipo de formación sea llevada a cabo por el profesorado universitario, dado que el nuevo horizonte que se dibuja en las instituciones de enseñanza superior demandan un perfil “tecnológico” de sus docentesThe designated society of the knowledge is found demanding a professorship that knows to work with the technologies of the information and the communication in addition to knowing to make it in a way collaborative. From this article we draw reasons so that this type of training will be carried out by the university professorship since the new horizon that is drawn in the teaching institutions superior demand a profile "technological" of their educationa

Actualización de las fichas técnicas de aseguramiento de energías peligrosas en tropical coffee COMPANY S.A.S

El presente trabajo de investigación tendrá como punto de referencia diseñar una propuesta de mejoramiento para el control de energías peligrosas mediante la actualización de las fichas técnicas de aseguramiento de energías peligrosas según la normativa RETIE en la empresa Tropical Coffee en el distrito de Santa Marta. El uso generalizado de la electricidad ha sido posible porque los medios tecnológicos permiten su manipulación, pero su propia naturaleza conlleva peligros que exigen un cuidadoso manejo preventivo. Los peligros inherentes a un flujo de corriente eléctrica para una persona son principalmente por contacto, es decir, la electricidad pasa por el cuerpo y ocasiona lesiones, que, dependiendo de factores como la tensión, la intensidad de la corriente, la resistencia y el tiempo del contacto puede ocasionar daños leves, severos e incluso la muerte. La formación de chispas eléctricas causa quemaduras por altas temperaturas y por radiación infrarroja y ultravioleta que también producen graves lesiones cutáneas y visuales. Las causas de los riesgos por la manipulación de algún sistema de energías peligrosas provienen principalmente del desconocimiento de las características de la energía eléctrica y de su potencial lesivo, lo cual puede generar: la construcción de instalaciones eléctricas defectuosas, la ampliación, adecuación y mantenimiento sin cumplimiento de normas que el sistema genere alta humedad, baja calidad de los elementos instalados, falta de distancias de seguridad suficientes, proximidad de otros conductores o de fuentes de calor, posibilidad de acceso de personas no autorizadas y falta de medidas de control para realizar reparaciones eléctricas. (Mancera, etal 2012)

Oxidative stress is tightly regulated by cytochrome c phosphorylation and respirasome factors in mitochondria

Respiratory cytochrome c has been found to be phosphorylated at tyrosine 97 in the postischemic brain upon neuroprotective insulin treatment, but how such posttranslational modification affects mitochondrial metabolism is unclear. Here, we report the structural features and functional behavior of a phosphomimetic cytochrome c mutant, which was generated by site-specific incorporation at position 97 of p-carboxymethyl-l-phenylalanine using the evolved tRNA synthetase method. We found that the point mutation does not alter the overall folding and heme environment of cytochrome c, but significantly affects the entire oxidative phosphorylation process. In fact, the electron donation rate of the mutant heme protein to cytochrome c oxidase, or complex IV, within respiratory supercomplexes was higher than that of the wild-type species, in agreement with the observed decrease in reactive oxygen species production. Direct contact of cytochrome c with the respiratory supercomplex factor HIGD1A (hypoxia-inducible domain family member 1A) is reported here, with the mutant heme protein exhibiting a lower affinity than the wild-type species. Interestingly, phosphomimetic cytochrome c also exhibited a lower caspase-3 activation activity. Altogether, these findings yield a better understanding of the molecular basis for mitochondrial metabolism in acute diseases, such as brain ischemia, and thus could allow the use of phosphomimetic cytochrome c as a neuroprotector with therapeutic applications.España, Junta de Andalucía BIO-198España MINECO BFU2015-71017/BM

The atypical iron-coordination geometry of cytochrome f remains unchanged upon binding to plastocyanin, as inferred by XAS

The transient complex between cytochrome f and plastocyanin from the cyanobacterium Nostoc sp. PCC 7119 has been analysed by X-ray Absorption Spectroscopy in solution, using both proteins in their oxidized and reduced states. Fe K-edge data mainly shows that the atypical metal coordination geometry of cytochrome f, in which the N-terminal amino acid acts as an axial ligand of the heme group, remains unaltered upon binding to its redox partner, plastocyanin. This fact suggests that cytochrome f provides a stable binding site for plastocyanin and minimizes the reorganization energy required in the transient complex formation, which could facilitate the electron transfer between the two redox partners

First adequately-known quadrupedal sirenian from Eurasia (Eocene, Bay of Biscay, Huesca, northeastern Spain)

Sirenians are the only extant herbivorous mammals fully adapted to an aquatic lifestyle. They originated in Africa during the Paleocene from an undetermined clade of afrotherian mammals, and by the end of the Eocene they were widely distributed across the tropical latitudes. Here we introduce Sobrarbesiren cardieli gen. et sp. nov. It is the first adequately-known quadrupedal sirenian from Eurasia and the oldest record of this clade from western Europe. Fossils have been recovered from the middle Lutetian (SBZ15) site of Castejón de Sobrarbe-41 (Huesca, Spain), and comprise many cranial and postcranial remains, including pelvic girdle and hind limb bones, from at least six sirenian individuals of different ontogenetic stages. Sobrarbesiren shows a suite of characters previously considered synapomorphies of different clades of derived sirenians, such as the presence of the processus retroversus of the squamosal and the pterygoid fossa, combined with ancestral characters such as the presence of an alisphenoid canal, a permanent P5, at least two sacral vertebrae, a primitive pelvis and functional femora and fibulae. Sobrarbesiren is recovered as the sister taxon of Dugongidae and represents a transitional stage of adaptation to aquatic life between the amphibious quadrupedal prorastomids and the aquatic quadrupedal protosirenids