The ESCRT machinery: new roles at new holes

The ESCRT machinery drives a diverse collection of membrane remodeling events, including multivesicular body biogenesis, release of enveloped retroviruses and both reformation of the nuclear envelope and cytokinetic abscission during mitotic exit. These events share the requirement for a topologically equivalent membrane remodeling for their completion and the cells deployment of the ESCRT machinery in these different contexts highlights its functionality as a transposable membrane-fission machinery. Here, we will examine recent data describing ESCRT-III dependent membrane remodeling and explore new roles for the ESCRT-III complex at the nuclear envelope

The complex biology of FOXO

FOXO transcription factors control proliferation, apoptosis, differentiation and metabolic processes. Loss of FOXO function has been identified in several human cancers, and results in increased cellular survival and a predisposition to neoplasia, especially in epithelial cancer. FOXO factors are therefore bona fide tumor suppressors, and their potential use as therapeutic targets in cancer has been a matter of debate. Importantly, FOXO factors can also positively regulate cell survival through the activation of several detoxification genes, complicating its putative therapeutic potential. Targeting of FOXO factors has also been proposed for the treatment of metabolic dysfunctions such as diabetes mellitus, immunological disorders and neurodegeneration, as well as for the prevention of aging by maintaining the hematopoyetic stem cells niche. But again, data has accumulated that cautions against the potential use of the FOXO activators in these settings. Therefore, greater understanding of the regulation of FOXO target specificity is still needed to boost its use as a therapeutic target. The four members of the FOXO family (FOXO1, FOXO3A, FOXO4 and FOXO6) have distinct but overlapping cellular functions, although they seem to bind a common set of DNA sites. This fact together with the observation that FOXOs are only partially dependent on their DNA binding activity to regulate their target genes highlights the fact that the interaction of the FOXOs with other transcription factors is crucial for the FOXO-mediated transcriptional programs. In this review, we provide an overview of recent progress in the understanding of the modulation of FOXO activity and target specificity by transcription factors and coactivators. © 2011 Bentham Science Publishers Ltd.This work was supported Ministry of Science and Innovation (grants SAF2006-01619, SAF2009-07599 and CSD 2007-00020 to M.M.). CNIC is supported by the Spanish Ministry of Health and Consumer Affairs and the Pro-CNIC Foundation.Peer Reviewe

The ESCRT machinery: remodeling, repairing, and sealing membranes

The ESCRT machinery is an evolutionarily conserved membrane remodeling complex that is used by the cell to perform reverse membrane scission in essential processes like protein degradation, cell division, and release of enveloped retroviruses. ESCRT-III, together with the AAA ATPase VPS4, harbors the main remodeling and scission function of the ESCRT machinery, whereas earlyacting ESCRTs mainly contribute to protein sorting and ESCRT-III recruitment through association with upstream targeting factors. Here, we review recent advances in our understanding of the molecular mechanisms that underlie membrane constriction and scission by ESCRT-III and describe the involvement of this machinery in the sealing and repairing of damaged cellular membranes, a key function to preserve cellular viability and organellar function

Caracterización del complejo regulador del sistema de protección frente a estrés oxidativo mitocondrial

La disfunción del endotelio vascular contribuye tanto al inicio como a la progresión y resolución de los procesos de aterosclerosis. Numerosos estudios apuntan al incremento anormal en los niveles celulares de especies reactivas de oxígeno (ROS), o estrés oxidativo, como un factor clave en la aparición de la disfunción endotelial y en su posterior evolución patológica.En el presente trabajo demostramos que el factor de transcripción FoxO3a es un regulador positivo directo de los genes implicados en la protección frente al estrés oxidativo de origen mitocondrial en células endoteliales primarias. Asimismo, proponemos que, para ejercer este efecto, FoxO3a requiere al coactivador transcripcional PGC-1α, ya que su actividad está considerablemente reducida en células endoteliales deficientes en PGC-1α. Este coactivador parece ser igualmente dependiente de la presencia de FoxO3a para regular la expresión de los genes del sistema antioxidante. La co-regulación observada parece estar mediada por la interacción directa entre ambos factores en el endotelio, como han puesto de manifiesto ensayos de interacción in vitro e in vivo. En este estudio proponemos además que la actividad del complejo PGC-1α-FoxO3a podría estar regulada por la deacetilasa SIRT1, que sería responsable de su estabilización en respuesta a una situación de estrés.Dada la importancia del mantenimiento de la homeostasis de los ROS para la funcionalidad del endotelio vascular, la regulación de la actividad del complejo PGC-1α-FoxO3a, así como de SIRT1, podría ser relevante para el desarrollo de nuevas aproximaciones terapéuticas para la patología vascular

Membrane binding by CHMP7 coordinates ESCRT-III dependent nuclear envelope reformation

SummaryIn addition to its role in membrane abscission during cytokinesis, viral budding, endosomal sorting, and plasma membrane repair [1], the endosomal sorting complex required for transport-III (ESCRT-III) machinery has recently been shown to seal holes in the reforming nuclear envelope (NE) during mitotic exit [2, 3]. ESCRT-III also acts during interphase to repair the NE upon migration-induced rupture [4, 5], highlighting its key role as an orchestrator of membrane integrity at this organelle. While NE localization of ESCRT-III is dependent upon the ESCRT-III component CHMP7 [3], it is unclear how this complex is able to engage nuclear membranes. Here we show that the N terminus of CHMP7 acts as a novel membrane-binding module. This membrane-binding ability allows CHMP7 to bind to the ER, an organelle continuous with the NE, and it provides a platform to direct NE recruitment of ESCRT-III during mitotic exit. CHMP7’s N terminus comprises tandem Winged-Helix domains [6], and, by using homology modeling and structure-function analysis, we identify point mutations that disrupt membrane binding and prevent both ER localization of CHMP7 and its subsequent enrichment at the reforming NE. These mutations also prevent assembly of downstream ESCRT-III components at the reforming NE and proper establishment of post-mitotic nucleo-cytoplasmic compartmentalization. These data identify a novel membrane-binding activity within an ESCRT-III subunit that is essential for post-mitotic nuclear regeneration

Internacionalización de Pymes: La exportación en el sector vitivinícola

El presente Trabajo de Fin de Grado trata sobre la internacionalización de pymes, más concretamente sobre la exportación en el sector vitivinícola. Se ha analizado la situación actual del sector en nuestro país, los factores determinantes a la internacionalización en las pymes y la situación y evolución de las exportaciones del sector. El sector vitivinícola es de gran relevancia en nuestro país ya que representa una parte importante en nuestra economía y es uno de los sectores que dan imagen a nuestro país en todo el mundo. Cómo caso práctico se ha estudiado la internacionalización llevada a cabo por una pequeña bodega zaragozana, en la que las exportaciones representan un porcentaje significativo sobre las ventas

Peroxisome proliferator activated receptors-α and -Υ, and cAMP-mediated pathways, control retinol-binding protein-4 gene expression in brown adipose tissue

Retinol binding protein-4 (RBP4) is a serum protein involved in the transport of vitamin A. It is known to be produced by the liver and white adipose tissue. RBP4 release by white fat has been proposed to induce insulin resistance. We analyzed the regulation and production of RBP4 in brown adipose tissue. RBP4 gene expression is induced in brown fat from mice exposed to cold or treated with peroxisome proliferator-activated receptor (PPAR) agonists. In brown adipocytes in culture, norepinephrine, cAMP, and activators of PPARγ and PPARα induced RBP4 gene expression and RBP4 protein release. The induction of RBP4 gene expression by norepinephrine required intact PPAR-dependent pathways, as evidenced by impaired response of the RBP4 gene expression to norepinephrine in PPARα-null brown adipocytes or in the presence of inhibitors of PPARγ and PPARα. PPARγ and norepinephrine can also induce the RBP4 gene in white adipocytes, and overexpression of PPARα confers regulation by this PPAR subtype to white adipocytes. The RBP4 gene promoter transcription is activated by cAMP, PPARα, and PPARγ. This is mediated by a PPAR-responsive element capable of binding PPARα and PPARγ and required also for activation by cAMP. The induction of the RBP4 gene expression by norepinephrine in brown adipocytes is protein synthesis dependent and requires PPARγ-coactivator-1-α, which acts as a norepinephine-induced coactivator of PPAR on the RBP4 gene. We conclude that PPARγ- and PPARα-mediated signaling controls RBP4 gene expression and releases in brown adipose tissue, and thermogenic activation induces RBP4 gene expression in brown fat through mechanisms involving PPARγ-coactivator-1-α coactivation of PPAR signaling.</jats:p

CDK1 controls CHMP7-dependent nuclear envelope reformation

Through membrane sealing and disassembly of spindle microtubules, the Endosomal Sorting Complex Required for Transport-III (ESCRT-III) machinery has emerged as a key player in the regeneration of a sealed nuclear envelope (NE) during mitotic exit, and in the repair of this organelle during interphase rupture. ESCRT-III assembly at the NE occurs transiently during mitotic (M) exit and is initiated when CHMP7, an ER-localised ESCRT-II/ESCRT-III hybrid protein, interacts with the Inner Nuclear Membrane (INM) protein LEM2. Whilst classical nucleocytoplasmic transport mechanisms have been proposed to separate LEM2 and CHMP7 during interphase, it is unclear how CHMP7 assembly is suppressed in mitosis when NE and ER identities are mixed. Here, we use live cell imaging and protein biochemistry to examine the biology of these proteins during M-exit. Firstly, we show that CHMP7 plays an important role in the dissolution of LEM2 clusters that form at the NE during M-exit. Secondly, we show that CDK1 phosphorylates CHMP7 upon M-entry at Ser3 and Ser441 and that this phosphorylation reduces CHMP7’s interaction with LEM2, limiting its assembly during M-phase. We show that spatiotemporal differences in the dephosphorylation of CHMP7 license its assembly at the NE during telophase, but restrict its assembly on the ER at this time. Without CDK1 phosphorylation, CHMP7 undergoes inappropriate assembly in the peripheral ER during M-exit, capturing LEM2 and downstream ESCRT-III components. Lastly, we establish that a microtubule network is dispensable for ESCRT-III assembly at the reforming nuclear envelope. These data identify a key cell-cycle control programme allowing ESCRT-III-dependent nuclear regeneration

Diplomado de profundización Acompañamiento Psicosocial en Escenarios de Violencia La imagen y la narrativa como herramientas para el abordaje psicosocial en escenarios de violencia en los municipios de Girardot, Tausa, Zipaquirá (Cundinamarca) Y Coello (Tolima).

Diplomado de profundización Acompañamiento Psicosocial en Escenarios de Violencia La imagen y la narrativa como herramientas para el abordaje psicosocial en escenarios de violencia en los municipios de Girardot, Tausa, Zipaquirá (Cundinamarca) Y Coello (Tolima).En este trabajo se muestra actividades de aprendizaje y reflexión de la imagen y la narrativa como un mecanismo de abordaje psicosocial en los escenarios de violencia, específicamente el conflicto interno en territorio colombiano. Inicialmente se realizó el análisis del relato de violencia y esperanza tomado del libro: Voces: Relatos de violencia y esperanza en Colombia, Editado por el Banco mundial en el año 2009, “relato # 2” Camilo y se planteó una serie de preguntas estratégicas, circulares y reflexivas para profundizar el contenido del relato. Posteriormente se procedió a realizar el análisis y presentación de estrategias de abordaje psicosocial del caso de la comunidad Cacarica teniendo en cuenta resolución de ítems orientadores correspondientes a: Emergentes psicosociales latentes después de la incursión y el hostigamiento militar, Impacto a la población por la estigmatización a ser cómplices de grupos armados. Con base en las respuestas a los ítems anteriores, se propone estrategias psicosociales para la comunidad de Cacarica, que ayuden a la potenciación de recursos de afrontamiento y superación. Mediante el trabajo individual de los integrantes del grupo, localizados en diferentes municipios del país, se desarrolló un informe analítico y reflexivo de la experiencia de foto voz, en contextos de cualquier tipo de violencia, utilizando como herramientas la imagen y la narrativa como clave de memoria para extraer nuevos significados sociales, recursos de afrontamiento, reflexión psicosocial y política sobre la experiencia, dejando registrado el desarrollo de ésta actividad en un blog y como reflexión unas conclusiones finales.This work shows learning activities and reflection of the image and the narrative as a mechanism of psychosocial approach in the scenarios of violence, specifically the internal conflict in Colombian territory. Initially, the analysis of the story of violence and hope was taken from the book: Voices: Stories of violence and hope in Colombia, Edited by the World Bank in 2009, “story # 2” Camilo and raised a series of strategic questions, circular and reflective to deepen the content of the story. Subsequently, the analysis and presentation of psychosocial approach strategies in the case of the Cacarica community were carried out, considering the resolution of guiding items corresponding to: Latent psychosocial emergencies after the incursion and military harassment, Impact on the population due to stigmatization of Be complicit in armed groups. Based on the answers to the previous items, psychosocial strategies are proposed for the community of Cacarica, which help to strengthen coping and overcoming resources. Through the individual work of the members of the group, located in different municipalities of the country, an analytical and reflective report of the photo voice experience was developed, in contexts of any type of violence, using as tools the image and the narrative as a key to memory to extract new social meanings, coping resources, psychosocial and political reflection on the experience, recording the development of this activity in a blog and as a reflection some final conclusion

Intravitreal injection analysis at the Bascom Palmer Eye Institute: evaluation of clinical indications for the treatment and incidence rates of endophthalmitis

To report the incidence of endophthalmitis, in addition to its clinical and microbiological aspects, after intravitreal injection of vascular-targeting agents. A retrospective review of a consecutive series of 10,142 intravitreal injections of vascular targeting agents (bevacizumab, ranibizumab, triamcinolone acetonide, and preservative-free triamcinolone acetonide) between June 1, 2007 and January 31, 2010, performed by a single service (TGM) at the Bascom Palmer Eye Institute. One case of clinically-suspected endophthalmitis was identified out of a total of 10,142 injections (0.009%), presenting within three days of injection of bevacizumab. The case was culture-positive for Staphylococcus epidermidis. Final visual acuity was 20/40 after pars plana vitrectomy surgery. In this series, the incidence of culture-positive endophthalmitis after intravitreal injection of vascular agents in an outpatient setting was very low. We believe that following a standardized injection protocol, adherence to sterile techniques and proper patient follow-up are determining factors for low incidence rates