Lifespan extension by calorie restriction relies on the Sty1 MAP kinase stress pathway

Either calorie restriction, loss of function of the nutrient-dependent PKA or TOR/SCH9 pathways, or activation of stress defences improves longevity in different eukaryotes. However, the molecular links between glucose depletion, nutrient-dependent pathways and stress responses are unknown. Here we show that either calorie restriction or inactivation of nutrient-dependent pathways induces life-span extension in fission yeast, and that such effect is dependent on the activation of the stress-dependent Sty1 MAP kinase. During transition to stationary phase in glucose-limiting conditions, Sty1 becomes activated and triggers a transcriptional stress program, whereas such activation does not occur under glucose-rich conditions. Deletion of the genes coding for the SCH9-homologue Sck2 or the Pka1 kinases, or mutations leading to constitutive activation of the Sty1 stress pathway increase life span under glucose-rich conditions, and importantly such beneficial effects depend ultimately on Sty1. Furthermore, cells lacking Pka1 display enhanced oxygen consumption and Sty1 activation under glucose-rich conditions. We conclude that calorie restriction favours oxidative metabolism, reactive oxygen species production and Sty1 MAP kinase activation, and this stress pathway favours life-span extension.

Genome-wide screen of genes required for caffeine tolerance in fission yeast

Background: An excess of caffeine is cytotoxic to all eukaryotic cell types. We aim to study how cells become tolerant to atoxic dose of this drug, and the relationship between caffeine and oxidative stress pathways.Methodology/Principal Findings: We searched for Schizosaccharomyces pombe mutants with inhibited growth on caffeinecontainingplates. We screened a collection of 2,700 haploid mutant cells, of which 98 were sensitive to caffeine. The genes mutated in these sensitive clones were involved in a number of cellular roles including the H2O2-induced Pap1 and Sty1 stress pathways, the integrity and calcineurin pathways, cell morphology and chromatin remodeling. We have investigated the role of the oxidative stress pathways in sensing and promoting survival to caffeine. The Pap1 and the Sty1 pathways are both required for normal tolerance to caffeine, but only the Sty1 pathway is activated by the drug. Cells lacking Pap1 aresensitive to caffeine due to the decreased expression of the efflux pump Hba2. Indeed, ?hba2 cells are sensitive to caffeine, and constitutive activation of the Pap1 pathway enhances resistance to caffeine in an Hba2-dependent manner. Conclusions/Significance: With our caffeine-sensitive, genome-wide screen of an S. pombe deletion collection, we havedemonstrated the importance of some oxidative stress pathway components on wild-type tolerance to the drug.

Deciphering 3'ss selection in the yeast genome reveals an RNA thermosensor that mediates alternative splicing

Poor understanding of the spliceosomal mechanisms to select intronic 3' ends (3'ss) is a major obstacle to deciphering eukaryotic genomes. Here, we discern the rules for global 3'ss selection in yeast. We show that, in contrast to the uniformity of yeast splicing, the spliceosome uses all available 3'ss within a distance window from the intronic branch site (BS), and that in 70% of all possible 3'ss this is likely to be mediated by pre-mRNA structures. Our results reveal that one of these RNA folds acts as an RNA thermosensor, modulating alternative splicing in response to heat shock by controlling alternate 3'ss availability. Thus, our data point to a deeper role for the pre-mRNA in the control of its own fate, and to a simple mechanism for some alternative splicing.

Generation of cardiomyocytes from new human embrionic stem cell lines derived from poor-quanlity blastocysts

Human embryonic stem (hES) cells represent a potential source for cell replacement therapy of many degenerative diseases. Most frequently, hES cell lines are derived from surplus embryos from assisted reproduction cycles, independent of their quality or morphology. Here, we show that hES cell lines can be obtained from poor-quality blastocysts with the same efficiency as that obtained from good- or intermediate-quality blastocysts. Furthermore, we show that the self-renewal, pluripotency, and differentiation ability of hES cell lines derived from either source are comparable. Finally, we present a simple and reproducible embryoid body-based protocol for the differentiation of hES cells into functional cardiomyocytes. The five new hES cell lines derived here should widen the spectrum of available resources for investigating the biology of hES cells and advancing toward efficient strategies of regenerative medicine.

Evaluation of the chicken transcriptome by SAGE of B cells and the DT40 cell line

Background: The understanding of whole genome sequences in higher eukaryotes depends to a large degree on the reliable definition of transcription units including exon/intron structures, translated open reading frames (ORFs) and flanking untranslated regions. The best currently available chicken transcript catalog is the Ensembl build based on the mappings of a relatively small number of full length cDNAs and ESTs to the genome as well as genome sequence derived in silico gene predictions.Results: We use Long Serial Analysis of Gene Expression (LongSAGE) in bursal lymphocytes and the DT40 cell line to verify the quality and completeness of the annotated transcripts. 53.6% of the more than 38,000 unique SAGE tags (unitags) match to full length bursal cDNAs, the Ensembl transcript build or the genome sequence. The majority of all matching unitags show single matches to the genome, but no matches to the genome derived Ensembl transcript build. Nevertheless, most of these tags map close to the 3' boundaries of annotated Ensembl transcripts.Conclusions: These results suggests that rather few genes are missing in the current Ensembl chicken transcript build, but that the 3' ends of many transcripts may not have been accurately predicted. The tags with no match in the transcript sequences can now be used to improve gene predictions, pinpoint the genomic location of entirely missed transcripts and optimize the accuracy of gene finder software.

Topological comparison of methods for predicting transcriptional cooperativity in yeast

Background: The cooperative interaction between transcription factors has a decisive role in the control of the fate of the eukaryotic cell. Computational approaches for characterizing cooperative transcription factors in yeast, however, are based on different rationales and provide a low overlap between their results. Because the wealth of information contained in protein interaction networks and regulatory networks has proven highly effective in elucidating functional relationships between proteins, we compared different sets of cooperative transcription factor pairs (predicted by four different computational methods) within the frame of those networks. Results: Our results show that the overlap between the sets of cooperative transcription factors predicted by the different methods is low yet significant. Cooperative transcription factors predicted by all methods are closer and more clustered in the protein interaction network than expected by chance. On the other hand, members of a cooperative transcription factor pair neither seemed to regulate each other nor shared similar regulatory inputs, although they do regulate similar groups of target genes. Conclusion: Despite the different definitions of transcriptional cooperativity and the different computational approaches used to characterize cooperativity between transcription factors, the analysis of their roles in the framework of the protein interaction network and the regulatory network indicates a common denominator for the predictions under study. The knowledge of the shared topological properties of cooperative transcription factor pairs in both networks can be useful not only for designing better prediction methods but also for better understanding the complexities of transcriptional control in eukaryotes.

El càncer de coll d'úter sota el microscòpi

 Treball de recerca realitzat per un alumne d’ensenyament secundari i guardonat amb un Premi CIRIT per fomentar l'esperit científic del Jovent l’any 2010. L’objectiu del treball ha estat estudiar i analitzar els diferents aspectes del càncer de cèrvix en profunditat, sobretot l'estudi citològic com a part del diagnòstic. L’ estudi teòric ha permès analitzar les generalitats de tots els tipus de càncer i la zona on es localitza el càncer de coll d'úter. Posteriorment, l’observació de les cèl•lules a través del microscopi ha permès deduir el tipus de cèl•lula o lesió de vint mostres diferents a partir de les característiques analitzades. S’han realitzat fotografies de les cèl•lules observades.

Estudi de la influència de substàncies en la proliferació cel·lular: el·laboració d'un cultiu cel·lular

 Treball de recerca realitzat per un alumne d’ensenyament secundari i guardonat amb un Premi CIRIT per fomentar l'esperit científic del Jovent l’any 2010. L’objectiu principal d'aquest treball de recerca és estudiar la manera com diverses substàncies afecten el creixement cel•lular in vitro. La hipòtesi principal és que algunes substàncies poden tenir un important efecte en el desenvolupament de les cèl•lules, perquè les substàncies modifiquen l'adherència de les cèl•lules a la placa de cultiu. Concretament, en aquest treball s'ha estudiat la possible influència de la poliornitina, el col•lagen i la polilisina en el creixement cel•lular in vitro de cèl•lules PC12 (cèl•lules tumorals de ronyó de rata) i 293 (cèl•lules embrionàries de ronyó humà). Per dur a terme aquest estudi és necessari utilitzar material de laboratori d'un nivell tècnic que sobrepassa els equipaments dels laboratoris dels Centres de Secundària. La cambra de flux laminar, per a poder manipular els cultius de manera estèril, incubadors cel•lulars estèrils i el microscopi invertit són equipaments imprescindibles per a poder treballar amb cultius cel•lulars. El Departament de Bioquímica de la Facultat de Medicina i Infermeria (Universitat de Lleida) ha posat a disposició de l'autor tots aquest equipaments i ha participat directament en la acció tutelar d'aquest estudi. Els resultats d'aquesta recerca han permès confirmar les hipòtesis principals que inicialment s'havien plantejat. S'ha constatat que les substàncies utilitzades tenen efectivament un influència decisiva en el creixement de les cèl•lules estudiades. Inicialment les substàncies utilitzades han afavorit el creixement cel•lular in vitro, exceptuant la polilisina, que ha resultat tòxica per a les cèl•lules 293. Ara bé, si el cultiu sobrecreix i la població sobrepassa un determinat llindar, les cèl•lules inicien la mort per apoptosi.

Estudio Farmacogenético en Pacientes con Cáncer de Pulmón No Microcítico Avanzado tratados con Quimioterapia basada en Platino

a partir de ADN genómico obtenido de las células nucleadas de sangre periférica de 103 pacientes con Cáncer de Pulmón No Microcítico (CPNM) avanzado tratados con quimioterapia basada en platino, hemos analizado la asociación entre supervivencia y cinco SNPs (Single Nucleotide Polymorphism) pertenecientes a dos grupos de genes: i) de la via metabólica del ácido fólico (Timidilato Sintetasa (TS), Metil-tetrahidrofolato Reductasa (MTHFR) y, ii) de la vía de reparación del ADN (Excision repair cross-complemeting group 1 (ERCC1) y Xeroderma pigmentosum group D (XPD).

Síntesi d'un fragment derivat del glutamat per a formar part d'un interruptor molecular

El projecte en el qual s’emmarca aquest treball de recerca es centra en el desenvolupament d’interruptors moleculars que permeten el control del funcionament d’un canal iònic de les cèl·lules del sistema nerviós central. En aquest treball de Màster en Experimentació Química, s’ha treballat, més concretament, en la síntesi del derivat del glutamat. S’ha dissenyat i desenvolupat una ruta sintètica del fragment de glutamat en 8 passos amb un 7% de rendiment global.

Estudi de la interacció de tres complexos de Pt amb proteïnes i oligonucleòtids mitjançant ESI-MS

En aquest treball s’investiga la reactivitat de tres complexos de Pt, cisplatí, complex 1, [Pt(dmba)(aza-N1)(dmso)], complex 2, i [Pt(dmba)(N9-9AA)(PPh3)]+, complex 3; els quals presenten activitat antitumoral, amb diferents proteïnes i oligonucleòtids mitjançant espectrometria de masses (ESI-TOF MS). ). L’estudi del cisplatí, 1, droga molt coneguda i emprada avui en dia pel tractament de molts tipus de càncer, permet comparar la reactivitat dels nous complexos d’estudi, 2 i 3, els quals presenten un IC50 més baix que el cisplatí en algunes línies de cèl·lules tumorals.

Defective TNF-alpha-mediated hepatocellular apoptosis and liver damage in acidic sphingomyelinase knockout mice

This study addressed the contribution of acidic sphingomyelinase (ASMase) in TNF-alpha-mediated hepatocellular apoptosis. Cultured hepatocytes depleted of mitochondrial glutathione (mGSH) became sensitive to TNF-alpha, undergoing a time-dependent apoptotic cell death preceded by mitochondrial membrane depolarization, cytochrome c release, and caspase activation. Cyclosporin A treatment rescued mGSH-depleted hepatocytes from TNF-alpha-induced cell death. In contrast, mGSH-depleted hepatocytes deficient in ASMase were resistant to TNF-alpha-mediated cell death but sensitive to exogenous ASMase. Furthermore, although in vivo administration of TNF-alpha or LPS to galactosamine-pretreated ASMase(+/+) mice caused liver damage, ASMase(-/-) mice exhibited minimal hepatocellular injury. To analyze the requirement of ASMase, we assessed the effect of glucosylceramide synthetase inhibition on TNF-alpha-mediated apoptosis. This approach, which blunted glycosphingolipid generation by TNF-alpha, protected mGSH-depleted ASMase(+/+) hepatocytes from TNF-alpha despite enhancement of TNF-alpha-stimulated ceramide formation. To further test the involvement of glycosphingolipids, we focused on ganglioside GD3 (GD3) because of its emerging role in apoptosis through interaction with mitochondria. Analysis of the cellular redistribution of GD3 by laser scanning confocal microscopy revealed the targeting of GD3 to mitochondria in ASMase(+/+) but not in ASMase(-/-) hepatocytes. However, treatment of ASMase(-/-) hepatocytes with exogenous ASMase induced the colocalization of GD3 and mitochondria. Thus, ASMase contributes to TNF-alpha-induced hepatocellular apoptosis by promoting the mitochondrial targeting of glycosphingolipids.

Moesin interacts with the cytoplasmic region of intercellular adhesion molecule-3 and is redistributed to the uropod of T Lymphocytes during cell polarization

During activation, T lymphocytes become motile cells, switching from a spherical to a polarized shape. Chemokines and other chemotactic cytokines induce lymphocyte polarization with the formation of a uropod in the rear pole, where the adhesion receptors intercellular adhesion molecule-1 (ICAM-1), ICAM-3, and CD44 redistribute. We have investigated membrane-cytoskeleton interactions that play a key role in the redistribution of adhesion receptors to the uropod. Immunofluorescence analysis showed that the ERM proteins radixin and moesin localized to the uropod of human T lymphoblasts treated with the chemokine RANTES (regulated on activation, normal T cell expressed, and secreted), a polarization-inducing agent; radixin colocalized with arrays of myosin II at the neck of the uropods, whereas moesin decorated the most distal part of the uropod and colocalized with ICAM-1, ICAM-3, and CD44 molecules. Two other cytoskeletal proteins, ß-actin and ¿-tubulin, clustered at the cell leading edge and uropod, respectively, of polarized lymphocytes. Biochemical analysis showed that moesin coimmunoprecipitates with ICAM-3 in T lymphoblasts stimulated with either RANTES or the polarization- inducing anti-ICAM-3 HP2/19 mAb, as well as in the constitutively polarized T cell line HSB-2. In addition, moesin is associated with CD44, but not with ICAM-1, in polarized T lymphocytes. A correlation between the degree of moesin-ICAM-3 interaction and cell polarization was found as determined by immunofluorescence and immunoprecipitation analysis done in parallel. The moesin-ICAM-3 interaction was specifically mediated by the cytoplasmic domain of ICAM-3 as revealed by precipitation of moesin with a GST fusion protein containing the ICAM-3 cytoplasmic tail from metabolically labeled Jurkat T cell lysates. The interaction of moesin with ICAM-3 was greatly diminished when RANTES-stimulated T lymphoblasts were pretreated with the myosin-disrupting drug butanedione monoxime, which prevents lymphocyte polarization. Altogether, these data indicate that moesin interacts with ICAM-3 and CD44 adhesion molecules in uropods of polarized T cells; these data also suggest that these interactions participate in the formation of links between membrane receptors and the cytoskeleton, thereby regulating morphological changes during cell locomotion.

Documento sobre células madre embrionarias

El grupo ha analizado las cuestiones referentes a la obtención y utilización de células embrionarias, llamadas células stem, células madre o células troncales, tema de extraordinaria importancia científica en el momento actual, que suscita reacciones encontradas, de gran carga ideológica, y ante el cual se requiere un debate socialinformado, que permita establecer el suficiente consenso para que se puedadar lugar a la correspondiente normativa jurídica.

Musculoskeletal manifestations in polymyalgia rheumatica and temporal arteritis.

To evaluate the incidence and characteristics of musculoskeletal manifestations in polymyalgia rheumatica (PMR) and temporal arteritis (TA). METHODS The records of 163 cases of PMR or TA diagnosed over a 15 year period in one area of Spain were reviewed for the presence and type of musculoskeletal manifestations. RESULTS Of 163 patients, 90 had isolated PMR and 73 had TA. Eighteen of the 90 patients (20%) with isolated PMR developed distal peripheral arthritis either at diagnosis or during the course of the disease. When it occurred, synovitis was mild, monoarticular or pauci-articular, asymmetrical, transient, and not destructive. Other distal manifestations observed in these patients were carpal tunnel syndrome and distal extremity swelling with pitting oedema. In all cases these manifestations occurred in conjunction with active PMR. As expected, PMR was the most frequent musculoskeletal manifestation in patients with TA, occurring in 56% of cases. On the contrary, only 11% of patients with TA developed peripheral arthritis. An important finding was that peripheral arthritis in these patients appears to be linked only temporally to the presence of simultaneous PMR and is not observed in its absence. Distal extremity swelling or defined polyarthritis were not observed. CONCLUSION The spectrum of distal musculoskeletal manifestations of PMR in our series is similar to that reported in other populations. By contrast, distal musculoskeletal symptoms are uncommon in TA. The almost complete absence of distal musculoskeletal manifestations in patients with pure TA suggests different mechanisms of disease in PMR and TA, supporting the view of two separate conditions or one common disease in which host susceptibility influences the clinical expression.