Transcriptional regulation of the ABCC6 gene and the background of impaired function of missense disease-causing mutations.

The human ATP-binding cassette family C member 6 (ABCC6) gene encodes an ABC transporter protein expressed primarily in the liver and to a lesser extent in the kidneys and the intestines. We review here the mechanisms of this restricted tissue-specific expression and the role of hepatocyte nuclear factor 4alpha which is responsible for the expression pattern. Detailed analyses uncovered further regulators of the expression of the gene pointing to an intronic primate-specific regulator region, an activator of the expression of the gene by binding CCAAT/enhancer-binding protein beta, which interacts with other proteins acting in the proximal promoter. This regulatory network is affected by various environmental stimuli including oxidative stress and the extracellular signal-regulated protein kinases 1 and 2 pathway. We also review here the structural and functional consequences of disease-causing missense mutations of ABCC6. A significant clustering of the missense disease-causing mutations was found at the domain-domain interfaces. This clustering means that the domain contacts are much less permissive to amino acid replacements than the rest of the protein. We summarize the experimental methods resulting in the identification of mutants with preserved transport activity but failure in intracellular targeting. These mutants are candidates for functional rescue by chemical chaperons. The results of such research can provide the basis of future allele-specific therapy of ABCC6-mediated disorders like pseudoxanthoma elasticum or the generalized arterial calcification in infancy

Deactivation processes in PsbA1-Photosystem II and PsbA3-Photosystem II under photoinhibitory conditions in the cyanobacterium Thermosynechococcus elongatus

AbstractThe sensitivity to high light conditions of Photosystem II with either PsbA1 (WT*1) or PsbA3 (WT*3) as the D1 protein was studied in whole cells of the thermophilic cyanobacterium Thermosynechococcus elongatus. When the cells are cultivated under high light conditions the following results were found: (i) The O2 evolution activity decreases faster in WT*1 cells than in WT*3 cells both in the absence and in the presence of lincomycin, a protein synthesis inhibitor; (ii) In WT*1 cells, the rate constant for the decrease of the O2 evolution activity is comparable in the presence and in the absence of lincomycin; (iii) The D1 content revealed by western blot analysis decays similarly in both WT*1 and WT*3 cells and much slowly than O2 evolution; (iv) The faster decrease in O2 evolution in WT*1 than in WT*3 cells correlates with a much faster inhibition of the S2-state formation; (v) The shape of the WT*1 cells is altered. All these results are in agreement with a photo-inhibition process resulting in the loss of the O2 activity much faster than the D1 turnover in PsbA1-PSII and likely to a greater production of reactive oxygen species under high light conditions in WT*1 than in WT*3. This latter result is discussed in view of the known effects of the PsbA1 to PsbA3 substitution on the redox properties of the Photosystem II cofactors. The observation that under low light conditions WT*3 cells are able to express the psbA3 gene, whereas under similar conditions wild type cells are expressing mainly the psbA1 gene is also discussed. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial

Evidence for different binding sites on the 33-kDa protein for DCMU, atrazine and QB

AbstractTwo DCMU-resistant strains of the cyanobacterium Synechocystis 6714 were used to analyse the binding sites of DCMU, atrazine and QB. DCMUr-IIA was DCMU and atrazine resistant; it presented an impaired electron flow and its 33-kDa protein was weakly attached to the membrane. DCMUr-IIB, derived from the former, simultaneously regained atrazine sensitivity, normal electron flow and a tight linkage of the 33-kDa protein to the membrane. This mutant shows that loss of DCMU binding does not necessarily affect the binding of either atrazine or QB. The role of the 33-kDa protein is discussed

EPR characterisation of the ferrous nitrosyl complex formed within the oxygenase domain of NO synthase.

International audienceNitric oxide is produced in mammals by a class of enzymes called NO synthases (NOSs). It plays a central role in cellular signalling but also has deleterious effects, as it leads to the production of reactive oxygen and nitrogen species. NO forms a relatively stable adduct with ferrous haem proteins, which, in the case of NOS, is also a key catalytic intermediate. Despite extensive studies on the ferrous nitrosyl complex of other haem proteins (in particular myoglobin), little characterisation has been performed in the case of NOS. We report here a temperature-dependent EPR study of the ferrous nitrosyl complex of the inducible mammalian NOS and the bacterial NOS-like protein from Bacillus subtilis. The results show that the overall behaviours are similar to those observed for other haem proteins, but with distinct ratios between axial and rhombic forms in the case of the two NOS proteins. The distal environment appears to control the existence of the axial form and the evolution of the rhombic form

Probing the role of chloride in Photosystem II from Thermosynechococcus elongatus by exchanging chloride for iodide

AbstractThe active site for water oxidation in Photosystem II (PSII) goes through five sequential oxidation states (S0 to S4) before O2 is evolved. It consists of a Mn4CaO5 cluster and TyrZ, a redox-active tyrosine residue. Chloride ions have been known for long time to be required for the function of the enzyme. However, X-ray data have shown that they are located about 7Å away from the Mn4CaO5 cluster, a distance that seems too large to be compatible with a direct involvement of chloride in the water splitting chemistry. We have investigated the role of this anion by substituting I− for Cl− in the cyanobacterium Thermosynechococcus elongatus with either Ca2+ or Sr2+ biosynthetically assembled into the Mn4 cluster. The electron transfer steps affected by the exchanges were investigated by time-resolved UV–visible absorption spectroscopy, time-resolved EPR at room temperature and low temperature cw-EPR spectroscopy. In both Ca-PSII and Sr-PSII, the Cl−/I− exchange considerably slowed down the two S3TyrZ•→(S3TyrZ•)′→S0 reactions in which the fast phase, S3TyrZ•→(S3TyrZ•)′, reflects the electrostatically triggered expulsion of one proton from the catalytic center caused by the positive charge near/on TyrZ• and the slow phase corresponds to the S0 and O2 formations and to a second proton release. The t1/2 for S0 formation increased from 1.1ms in Ca/Cl-PSII to ≈6ms in Ca/I-PSII and from 4.8ms in Sr/Cl-PSII to ≈45ms in Sr/I-PSII. In all cases the TyrZ• reduction was the limiting step. The kinetic effects are interpreted by a model in which the Ca2+ binding site and the Cl− binding site, although spatially distant, interact. This interaction is likely mediated by the H-bond and/or water molecules network(s) connecting the Cl− and Ca2+ binding sites by which proton release may be channelled

Impact de la personnalité sur la qualité de vie dans la maladie de Parkinson au stade des fluctuations motrices

Avec l'évolution de la maladie de Parkinson, la prise chronique de traitements dopaminergiques entraine l'apparition de fluctuations motrices chez les patients ce qui dégrade fortement leur Qualité de Vie (QdV). En conséquence, de nouveaux traitements dits de seconde ligne, comme la Stimulation Cérébrale Profonde des Noyaux Sous-Thalamiques (SCP-NST) ou la Perfusion Continue Sous-cutanée d'Apomorphine (CSAI), peuvent être proposés aux patients. Leur efficacité clinique est globalement reconnue, néanmoins aucune étude contrôlée randomisée n'a permis de comparer ces deux prises en charge pour lesquelles nous n'avons à ce jour identifié aucun facteur prédictif d'amélioration post-traitement. Ainsi, le principal objectif de ce travail de thèse était d'étudier l'impact des dimensions de personnalité sur l'amélioration de la QdV après ces traitements de seconde ligne chez des patients parkinsoniens au stade des fluctuations motrices. Pour ce faire, deux études ont été réalisées : 1) l'étude PSYCHO-STIM sur la SCP-NST, et 2) l'étude PSYCHO-PERF sur la CSAI. Ces deux études, subdivisées en différents sous-objectifs, ont permis : 1) de valider l'utilisation du questionnaire de personnalité le TCI ("Temperament and Character Inventory") dans une cohorte de patients atteints de maladie de Parkinson ; 2) de révéler une possible évolution de la personnalité des patients parkinsoniens au cours du temps ; et 3) d'identifier différentes associations entre dimensions de personnalité et QdV en prétraitement et en post-traitement après la SCP-NST et la CSAI. Ainsi, le TCI est adapté pour étudier la personnalité dans la MP où il présente de bonnes propriétés psychométriques. Il a permis de confirmer que les patients parkinsoniens présentaient une personnalité spécifique qui semble aussi changer avec l'évolution de la maladie. De plus, "l'Evitement du Danger" est associé à une moins bonne QdV chez les patients fluctuants, alors que "l'Auto-Détermination" prédit d'une meilleure QdV chez les patients en attente de SCP-NST. Enfin, deux dimensions de personnalité en préopératoire telles que la "Recherche de la Nouveauté" et la "Coopérativité" sont associées à une plus grande amélioration de QdV au décours de la SCP-NST ; alors qu'uniquement la "Dépendance à la Récompense" semble prédictive d'une meilleure amélioration de QdV après la CSAI. Ces résultats renforcent ainsi l'importance de la prise en compte de facteurs individuels lors de la mise en place de ces traitements de seconde génération auprès des patients parkinsoniens : les dimensions de personnalité pourraient alors être utilisées comme facteurs prédictifs d'amélioration de QdV après SCP-NST ou CSAI, en pratique clinique. Ce travail de thèse pourrait aussi déboucher sur la mise en place de programmes spécifiques d'éducation thérapeutique chez des patients ayant des dimensions de personnalité pouvant conduire à un risque de moins bonne réponse de QdV au décours de ces traitements de seconde ligne.Through Parkinson's Disease (PD) evolution, chronic use of dopaminergic treatments leads to motor fluctuations emergence in patients, which seriously deteriorates their Quality of Life (QoL). In turn, second line treatments, such as Deep Brain Stimulation of the Sub-Thalamic Nucleus (DBS-STN) or Continuous Subcutaneous Apomorphine Infusion (CSAI), can be proposed to the patients. Their clinical efficiency is largely accepted, nonetheless no randomized controlled trial has yet compared these two therapeutics for which we have not identify any predictive factor of post-treatment amelioration yet. Hence, the main objective of this PhD work was to study impact of personality dimensions on QoL amelioration after second line treatments in PD patients with motor fluctuations. To that end, two studies were carried out: 1) PSYCHO-STIM study on DBS-STN, and 2) PSYCHO-PERF on CSAI. Both studies, subdivided into different sub-objectives, have allowed: 1) to validate personality questionnaire TCI ("Temperament and Character Inventory") use in a cohort of PD patients; 2) to reveal a possible evolution of PD patients' personality over time; and 3) to identify different associations between personality dimensions and QoL in pre-treatment and post-treatment after DBS-STN and CSAI. Hence, the TCI is adapted to study personality in PD where it shows good psychometric proprieties. It confirms that PD patients have a specific personality which seems to change with PD course. Moreover, "Harm Avoidance" is associated with a worst QoL in fluctuating patients, while "Self-Directedness" predicts a better QoL in patients awaiting DBS-STN. Lastly, two preoperative personality dimensions such as "Novelty Seeking" and "Cooperativeness" are associated with better QoL amelioration following DBS-STN; while only Reward Dependence seems to be predictive of better QoL amelioration after CSAI. Thus, these results strengthen the importance of individual factors inclusion before introduction of these second line treatments: personality dimensions could therefore be used as predictive factors of amelioration after DBS-STN or CSAI in clinical practice. Finally, this PhD work could also lead to introduction of specific therapeutic educational programs in patients presenting personality dimensions that may lead to a risk of lower QoL outcome following second line treatments

El sinsentido como problema hermenéutico en el fenómeno de las nuevas tecnologías*

El propósito de este artículo es mostrar cómo el olvido del Ser (Seinsvergessenheit) del primer Heidegger se puede aplicar a su segunda fase en la que se cuestiona por el fenómeno de la técnica. Se mostrará el sinsentido en el mundo poscapitalista-globalizado como un olvido del Ser del hombre, partiendo de la propuesta hermenéutica heideggeriana. Al mismo tiempo se explicará el fenómeno de las nuevas tecnologías, partiendo de la pregunta por la técnica de Heidegger. En otras palabras, se intentará mostrar cómo el pensador alemán nos presenta el problema del sentido-sinsentido desde la hermenéutica y la fenomenología. DOI: http://dx.doi.org/10.22518/16578953.717  

Las dimensiones políticas de Heidegger en la trilogía: Pueblo-Lenguaje-Ser

El pensador alemán Martin Heidegger nunca escribió sobre política, por eso es difícil encontrar en su extensa obra referencias o reflexiones sobre la política. El propósito es mostrar las dimensiones políticas de Heidegger basándose en una interpretación condensada en la trilogía pueblo-lenguajeser, en la que sí es evidente esta dimensión en su obra. Hay un episodio de la vida del pensador alemán cuando fue rector de la Freiburg Universität (Universidad de Friburgo) en 1933, que lo condena políticamente de estar vinculado al nacional socialismo. Este hecho ha desatado controversia y reacciones frente a la propuesta de Heidegger en el pensar. Se mostrarán dos de ellas una a favor y otra contra Heidegger para presentar las diferentes y opuestas reacciones que alcanza la propuesta heideggeriana. Por último se intentará mostrar que la trilogía pueblo-lenguaje-ser podría ayudar a resolver vacíos en la política que generan violencia en los pueblos actuales DOI: http://dx.doi.org/10.22518/16578953.77

La fin des apparences

Étrange situation que celle où l’on en est réduit à invoquer la loi de 1955… au nom des principes du constitutionnalisme. À plusieurs reprises durant les débats parlementaires, le projet de loi d’urgence sanitaire a été présenté par la majorité comme étant « inspiré » du « modèle » de la loi du 3 avril 1955. Une inspiration bien sélective néanmoins : le projet de loi déposé au Sénat après avis du Conseil d’État ne mentionne pas le principe du contrôle parlementaire renforcé des mesures prises dans le cadre de l’état d’urgence sanitaire. Il sera rétabli avec un certain recul par rapport à ce que prévoit la loi de 1955 et cela à un double niveau : celui de l’intervention du Parlement pour proroger l’état d’urgence sanitaire, et celui du contrôle parlementaire des mesures prises en période d’état d’urgence sanitaire. Cette contribution étudie les arguments développés au cours des débats parlementaires à propos de la loi du 23 mars 2020, loi d’urgence pour lutter contre le covid-19, afin de montrer la perception discutable du contrôle parlementaire qui s’en dégage

Olvido del ser: sentido-sinsentido del hombre en dimensiones de la técnica

En el siglo XXI, el fenómeno de la técnica moderna se presenta en las nuevas tecnologías. Se podría afirmar que las redes de las nuevas tecnologías tienen atrapado al hombre en un sentidosinsentido. El sentido es el instrumento de la técnica, que avanza desmesuradamente, desatando, simultáneamente, el sin-sentido del hombre. El pensador alemán Martín Heidegger reflexiona sobre este fenómeno, interpretando este sinsentido como el olvido del ser y una reducción del logos presocrático a ratio. El propósito es mostrar este sinsentido en la actualidad como un olvido del ser del hombre y del hombre mismo. Se expondrá cómo la técnica moderna no sólo intenta hacer de la naturaleza un instrumento sino también al hombre y a la razón, pues el logos se ha reducido a “razón instrumental”, actualizando el término a “razón tecnificada”. DOI: http://dx.doi.org/10.22518/16578953.75