The mitochondrial stress response and its impact on prohibitin-mediated aging phenotypes

Programa de Doctorado en Biotecnología y Tecnología QuímicaLínea de Investigación: Modelos Animales en Biotecnología y BiomedicinaClave Programa: DBICódigo Línea: 22Aging is a natural progression that affects all living organisms from birth, through maturity, to old age. It is characterized by a decline of the physiological integrity and it is accompanied by a higher incidence of age-related diseases, which represent nowadays the most common reason of death. Understanding the aging process has always been of interest. Initially it was thought to be the result of stochastic degradation but, nowadays, it is widely acknowledged that aging is controlled, at least in part, by genetic pathways and biochemical mechanisms. In this work, we focus in mitochondrial dysfunction as one of the most important processes regulating aging. Proper mitochondrial activity is preserved through regulation of mitochondrial dynamics and mitophagy and through proper maintenance of mitochondrial homeostasis. Under proteotoxic conditions the mitochondrial unfolded protein response, UPRmt, is activated to maintain mitochondrial proteostasis by inducing the expression of mitochondrial chaperones and proteases that control protein folding, assembly and degradation. The mitochondrial prohibitin, PHB, complex is a ring-like structure sitting in the inner mitochondrial membrane. It is composed of two subunits, PHB-1 and PHB-2, that are highly evolutionary conserved. PHBs have been related with many different functions: maintenance of nucleoids organization and stability, protection of newly synthesized mitochondrial proteins, assistance in folding and formation of the respiration super-complexes or acting as scaffold protein. Lack of PHB results in embryonic lethality in Caenorhabditis elegans, while homozygous PHB deletion mutants develop into sterile adults due to maternal contribution. In addition, deletion of PHB induces a very strong mitochondrial stress response. In this work, we show that the induction of UPRmt upon PHB deletion does not require the canonical components of the stress response, suggesting an alternative signalling mechanism. We present a sorting strategy capable of selecting homozygous mutants carrying the UPRmt-GFP stress reporter from GFP-balanced animals at the second larval stage. Because sorting is not completely error-free, we developed an automated high-throughput image analysis protocol that identifies and discards animals carrying the chromosome balancer. This method allows the study of balanced lethal mutations in a high-throughput manner. It can be easily adapted depending on the user¿s requirements and should serve as a useful resource for the C. elegans community for probing new biological aspects of essential nematode genes as well as the generation of more comprehensive genetic networks. In a chromosome-wide RNAi screen for C. elegans genes having human orthologues, we uncovered both known and new PHB genetic interactors affecting the UPRmt and growth. Interestingly, depletion of PHB shows an opposite effect on aging: it shortens lifespan in wild-type worms while it dramatically extends the longevity of the already long-lived insulin/IGF-1 signaling (IIS) pathway mutants. Moreover, the strong mitochondrial stress response elicited upon PHB depletion is remarkably reduced in IIS mutants. We aim at identifying new pathways involved in the regulation of the PHB-mediated mitochondrial stress response, as well as mechanisms responsible for the opposite longevity outcomes of PHB depletion. Towards this aim, we carried out genome-wide RNAi screens in PHB-depleted wild type animals and PHB-depleted IIS mutants. By performing GO term enrichment analysis, we identify inhibition of protein degradation, disruption of mitochondrial integrity and impairment of ATP synthesis as processes increasing the mitochondrial stress response. Moreover, we report a boost in the mitochondrial stress response as a mechanism to cope with the inhibition of other stress responses, such as nutrient sensing or defense response. Besides, inhibition of processes that are very energy consuming, such as protein biogenesis or ATP hydrolysis, reduced the mitochondrial stress response. In particular, we describe two new regulators of the mitochondrial stress response, two transcription factors, C16A3.4 and TLF-1. Furthermore, a new role for chromatin organization emerge in the regulation of the UPRmt and lifespan in an insulin dependent manner. We identify USP-48, a deubiquitinase, as an important factor for the enhanced lifespan of daf-2 mutants. Additionally, we establish a histone H2A, HIS-65, as a modulator of the mitochondrial stress response and aging in PHB-depleted daf-2 mutants. In this work thus, we pinpoint new players involved in the regulation of the mitochondrial stress response. These results will unveil the molecular pathways regulating mitochondrial quality control mechanisms and shed some light on the processes contributing to the differential effect in aging of PHB depletion in wild type and metabolically compromised animals.Universidad Pablo de Olavide de Sevilla. Departamento de Biología Molecular e Ingeniería BioquímicaPostprin

Archivos de arquitectura “en abierto”

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Osteología postcraneal de Tropidurus torquatus (Iguanidae)

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El presente Trabajo de Fin de Grado aborda, mediante la realización de una investigación de mercado, el desarrollo de nuevos productos y modelos de negocio basados en tecnología IoT. En concreto, la solución propuesta consiste en un nuevo servicio que podrían ofrecer las empresas gestoras de estaciones de esquí destinado a incrementar la seguridad de los niños mediante su localización en tiempo real. Se pretende, mediante este servicio, aportar a los usuarios de las estaciones de esquí un valor añadido ofreciendo también la posibilidad de contar con estadísticas y datos sobre lo esquiado.Para su elaboración, se han realizado distintos análisis, estudiando la competencia, la demanda, la economía o la tecnología a emplear. Para conocer la opinión de distintos usuarios, se ha desarrollado un Grupo de discusión, donde se han tratado los temas de más relevancia para el proyecto. Finalmente, tras la realización de dichos análisis y del Grupo de discusión, se expone la que considero la forma más rentable de implantar y ofrecer el servicio desarrollado.<br /

Ni-Co Alloy and Multisegmented Ni/Co Nanowire Arrays Modulated in Composition: Structural Characterization and Magnetic Properties

Design of novel multisegmented magnetic nanowires can pave the way for the next generation of data storage media and logical devices, magnonic crystals, or in magneto-plasmonics, among other energy conversion, recovery, and storage technological applications. In this work, we present a detailed study on the synthesis, morphology, structural, and magnetic properties of Ni, Co, and Ni-Co alloy and multisegmented Ni/Co nanowire

Study of ostracod assemblage in recent sediments of ponds from Bardenas Reales de Navarra

En este trabajo se estudian dos sondeos realizados en dos balsas actuales (Cortinas y Piezarrey) de Bardenas Reales de Navarra, para determinar la evolución ambiental reciente de las dos balsas, que presentan una asociación de facies diferente. La balsa de las Cortinas muestra una mayor estabilidad en la lámina de agua hacia la actualidad, con el consecuente establecimiento de un medio cada vez más favorable para el desarrollo de ostrácodos. Actualmente, esta balsa está afectada por un agua cálida, mesohalina, ligeramente básica y con alto contenido en oxígeno disuelto, siendo abundante en la asociación viva Limnocythere inopinata. La balsa de Piezarrey se caracteriza por sufrir una colmatación en los últimos años, con la consiguiente disminución de la lámina de agua. Esto da origen a condiciones muy eutrofizadas que serían desfavorables para el mantenimiento de un ecosistema rico y diverso. La influencia en la actualidad de un agua cálida, oligohalina, básica y con alto contenido en oxígeno disuelto, favorece el predominio de Cypridopsis vidua en esta balsaIn this paper we study two cores recovered in two recent ponds (Cortinas and Piezarrey) from Bardenas Reales de Navarra to determine the recent environmental evolution of two ponds having a different facies association. The pond of Cortinas presents greatest stability in a water level through time, with the consequent establishment of the environment for the development of ostracods. Recently, this pond is affected by warm,mesohaline and slightly basic water with high dissolved oxygen content, being abundant Limnocythere inopinata in the living assemblage. The pond of Piezarrey is characterized by having a silting during the last years and the consequent decrease in the water level. This generates very eutrophicathes conditions that would be unfavorable to the maintenance of a rich and diverse ecosystem. The recent influence of warm, oligohaline and basic water with high dissolved oxygen content favors the dominance of Cypridopsis vidua in this pon

Prohibitin-mediated lifespan and mitochondrial stress implicate SGK-1, insulin/IGF and mTORC2 in C. elegans

This is an open-access article distributed under the terms of the Creative Commons Attribution License.Lifespan regulation by mitochondrial proteins has been well described, however, the mechanism of this regulation is not fully understood. Amongst the mitochondrial proteins profoundly affecting ageing are prohibitins (PHB-1 and PHB-2). Paradoxically, in C. elegans prohibitin depletion shortens the lifespan of wild type animals while dramatically extending that of metabolically compromised animals, such as daf-2-insulin-receptor mutants. Here we show that amongst the three kinases known to act downstream of daf-2, only loss of function of sgk-1 recapitulates the ageing phenotype observed in daf-2 mutants upon prohibitin depletion. Interestingly, signalling through SGK-1 receives input from an additional pathway, parallel to DAF-2, for the prohibitin-mediated lifespan phenotype. We investigated the effect of prohibitin depletion on the mitochondrial unfolded protein response (UPRmt). Remarkably, the lifespan extension upon prohibitin elimination, of both daf-2 and sgk-1 mutants, is accompanied by suppression of the UPRmtinduced by lack of prohibitin. On the contrary, gain of function of SGK-1 results in further shortening of lifespan and a further increase of the UPRmtin prohibitin depleted animals. Moreover, SGK-1 interacts with RICT-1 for the regulation of the UPRmtin a parallel pathway to DAF-2. Interestingly, prohibitin depletion in rict-1 loss of function mutant animals also causes lifespan extension. Finally, we reveal an unprecedented role for mTORC2-SGK-1 in the regulation of mitochodrial homeostasis. Together, these results give further insight into the mechanism of lifespan regulation by mitochondrial function and reveal a cross-talk of mitochondria with two key pathways, Insulin/IGF and mTORC2, for the regulation of ageing and stress response.This work was funded by grants from the European Research Council (ERC-2011-StG-281691) and the Spanish Ministerio de Economía y Competitividad (BFU2012-35509) to M.A.S. The study was also supported by grants from the Deutsche Forschungsgemeinschaft DFG (SFB746, SFB850) to R.B. and from BIOSS Centre for Biological Signalling Studies to R.B and M.A.S.Peer Reviewe

Combined flow cytometry and high-throughput image analysis for the study of essential genes in Caenorhabditis elegans

Background: Advances in automated image-based microscopy platforms coupled with high-throughput liquid workflows have facilitated the design of large-scale screens utilising multicellular model organisms such as Caenorhabditis elegans to identify genetic interactions, therapeutic drugs or disease modifiers. However, the analysis of essential genes has lagged behind because lethal or sterile mutations pose a bottleneck for high-throughput approaches, and a systematic way to analyse genetic interactions of essential genes in multicellular organisms has been lacking. Results: In C. elegans, non-conditional lethal mutations can be maintained in heterozygosity using chromosome balancers, commonly expressing green fluorescent protein (GFP) in the pharynx. However, gene expression or function is typically monitored by the use of fluorescent reporters marked with the same fluorophore, presenting a challenge to sort worm populations of interest, particularly at early larval stages. Here, we develop a sorting strategy capable of selecting homozygous mutants carrying a GFP stress reporter from GFP-balanced animals at the second larval stage. Because sorting is not completely error-free, we develop an automated high-throughput image analysis protocol that identifies and discards animals carrying the chromosome balancer. We demonstrate the experimental usefulness of combining sorting of homozygous lethal mutants and automated image analysis in a functional genomic RNA interference (RNAi) screen for genes that genetically interact with mitochondrial prohibitin (PHB). Lack of PHB results in embryonic lethality, while homozygous PHB deletion mutants develop into sterile adults due to maternal contribution and strongly induce the mitochondrial unfolded protein response (UPR mt ). In a chromosome-wide RNAi screen for C. elegans genes having human orthologues, we uncover both known and new PHB genetic interactors affecting the UPR mt and growth. Conclusions: The method presented here allows the study of balanced lethal mutations in a high-throughput manner. It can be easily adapted depending on the user's requirements and should serve as a useful resource for the C. elegans community for probing new biological aspects of essential nematode genes as well as the generation of more comprehensive genetic networks.European Research Council ERC-2011-StG-281691Ministerio de Economía y Competitividad BFU2012–3550