Nuclear Outsourcing of RNA Interference Components to Human Mitochondria

MicroRNAs (miRNAs) are small non-coding RNAs that associate with Argonaute proteins to regulate gene expression at the post-transcriptional level in the cytoplasm. However, recent studies have reported that some miRNAs localize to and function in other cellular compartments. Mitochondria harbour their own genetic system that may be a potential site for miRNA mediated post-transcriptional regulation. We aimed at investigating whether nuclear-encoded miRNAs can localize to and function in human mitochondria. To enable identification of mitochondrial-enriched miRNAs, we profiled the mitochondrial and cytosolic RNA fractions from the same HeLa cells by miRNA microarray analysis. Mitochondria were purified using a combination of cell fractionation and immunoisolation, and assessed for the lack of protein and RNA contaminants. We found 57 miRNAs differentially expressed in HeLa mitochondria and cytosol. Of these 57, a signature of 13 nuclear-encoded miRNAs was reproducibly enriched in mitochondrial RNA and validated by RT-PCR for hsa-miR-494, hsa-miR-1275 and hsa-miR-1974. The significance of their mitochondrial localization was investigated by characterizing their genomic context, cross-species conservation and instrinsic features such as their size and thermodynamic parameters. Interestingly, the specificities of mitochondrial versus cytosolic miRNAs were underlined by significantly different structural and thermodynamic parameters. Computational targeting analysis of most mitochondrial miRNAs revealed not only nuclear but also mitochondrial-encoded targets. The functional relevance of miRNAs in mitochondria was supported by the finding of Argonaute 2 localization to mitochondria revealed by immunoblotting and confocal microscopy, and further validated by the co-immunoprecipitation of the mitochondrial transcript COX3. This study provides the first comprehensive view of the localization of RNA interference components to the mitochondria. Our data outline the molecular bases for a novel layer of crosstalk between nucleus and mitochondria through a specific subset of human miRNAs that we termed ‘mitomiRs’

Pitfalls in Monitoring Mitochondrial Temperature Using Charged Thermosensitive Fluorophores

Mitochondria are the source of internal heat which influences all cellular processes. Hence, monitoring mitochondrial temperature provides a unique insight into cell physiology. Using a thermosensitive fluorescent probe MitoThermo Yellow (MTY), we have shown recently that mitochondria within human cells are maintained at close to 50 °C when active, increasing their temperature locally by about 10 °C. Initially reported in the HEK293 cell line, we confirmed this finding in the HeLa cell line. Delving deeper, using MTY and MTX (MitoThermo X), a modified version of MTY, we unraveled some caveats related to the nature of these charged fluorophores. While enabling the assessment of mitochondrial temperature in HEK and HeLa cell lines, the reactivity of MTY to membrane potential variations in human primary skin fibroblasts precluded local temperature monitoring in these cells. Chemical modification of MTY into MTX did not result in a temperature probe unresponsive to membrane potential variations that could be universally used in any cell type to determine mitochondrial temperature. Thus, the cell-type dependence of MTY in measuring mitochondrial temperature, which is likely due to the variable binding of this dye to specific internal mitochondrial components, should imply cautiousness while using these nanothermometers for mitochondrial temperature analysis

Coût de revient du suivi de la warfarine en clinique d’anticoagulothérapie

Résumé Introduction : Le cout global de la surveillance de la thérapie à la warfarine est inconnu. Il est donc difficile d’estimer les retombees pharmacoeconomiques des nouveaux anticoagulants ne necessitant aucun monitorage. Objectifs : Determiner le cout direct de l’obtention, de l’analyse et de l’interpretation du rapport normalise international selon le lieu de prelevement de l’echantillon dans la perspective du systeme de sante quebecois. Méthodologie : La population etudiee est constituee de tous les dossiers suivis par notre programme d’anticoagulotherapie entre le 1er avril 2008 et le 31 mars 2009. Le cout du rapport normalise international est tire du Répertoire québécois et système de mesure des procédures de biologie médicale. On a utilise les salaires moyens ou medians, y compris les charges de l’employeur. Le cout moyen par visite a domicile a ete determine par un echantillonnage de 50 professionnels des centres de sante et de services sociaux participants afin de determiner la duree d’une visite et le nombre moyen de kilomètres parcourus par visite. Résultats : En moyenne, la surveillance de la warfarine coute 7,62 $par rapport numerise international effectue, y compris l’analyse. Cinquante pour cent (50$ pour l’execution et l’analyse d’un rapport numerise international. La surveillance de l’anticoagulation a court terme coute 89,92 $pour l’episode entier, alors que le cout annuel pour un traitement a long terme est de 137,16$ par patient. Lorsque les prelevements doivent etre effectues a domicile, le cout annuel s’eleve a 694,08 $par patient. Conclusions : Cette recherche permet de connaître le coût global de la surveillance de la warfarine et d’estimer les retombees economiques des nouveaux anticoagulants oraux.Abstract Introduction: The global cost of monitoring warfarin therapy is unknown. It is thus difficult to estimate the pharmacoeconomic consequences of new anticoagulants that do not require any monitoring. Objectives: Within the perspective of the Quebec health system, to determine the direct costs related to acquisition, analysis, and interpretation of the international normalized ratio (INR) according to where the sample was drawn. Methods: The study population consisted of all patients followed in our anticoagulation program from April 1, 2008–March 31, 2009. The cost associated with the international normalized ratio was obtained from the Repertoire quebecois et systeme de mesure des procedures de biologie medicale. We used average or median salaries, including employer fees. The average cost per home visit was determined using a sampling of 50 professionals from participating Health and Social Service Centres (CSSS), this in order to determine the length of a visit and the average number of kilometers covered per visit. Results: On average, warfarin monitoring costs$7.62 per measured INR, including analysis. Fifty percent (50%) of patients were followed at home. The cost then increases to $30.94 for the execution and analysis of an INR. Monitoring anticoagulation on a short-term basis costs$89.92 for the entire episode, whereas the annual cost for long-term treatment is $137.16 per patient. When sampling is done at home, the annual cost increases to$694.08 per patient. Conclusion: This study established the global cost of monitoring warfarin and estimated the economic impact of the new oral anticoagulants

L'importance du mode de mise en place des materiaux pedologiques dans l'organisation des sols : origine et caracteristiques de l'espace poral

National audienc

L’autoformation à l’harmonisation travail-vie personnelle : une action concertée des personnes en emploi, des employeurs et des syndicats

Cet article documente les avantages et les limites d’une démarche d’autoformation à l’harmonisation travail-vie personnelle (HTVP) destinée aux personnes en emploi, aux employeurs et aux syndicats. Les résultats suggèrent une diminution du conflit et une augmentation de l’enrichissement travail-vie personnelle chez les personnes en emploi, lorsque les employeurs et les représentants syndicaux ont été sensibilisés et outillés en matière d’HTVP. L’autoformation constitue un outil de gestion des ressources humaines pour améliorer la qualité de vie au travail, pour se démarquer et pour développer une culture organisationnelle favorable à l’HTVP. Les limites de l’autoformation sont le manque de temps et de ressources pour s’engager dans une démarche autogérée.This article documents the benefits and limitations of a self-training program on work-life balance intended for workers, employers, and labor union representatives. Results show less conflict and an improvement in work-life enrichment among workers. Results also show employers and labor union representatives became more aware of work-life balance issues within their organisation. Self-training programs on work-life balance constitute a useful human resources management tool to improve quality of life at work and gain a competitive edge. The limits of the self-training program experienced by workers, employers, and labor union representatives include lack of time and resources to a dequately complete the training

Conception et usage d’un environnement virtuel éducatif. Quelles spécifications didactiques pour faire apprendre la complexité de la gestion durable de la forêt ?

International audienc

Conception et usage d’un environnement virtuel éducatif. Quelles spécifications didactiques pour faire apprendre la complexité de la gestion durable de la forêt ?

International audienc

Conception et usage d’un environnement virtuel éducatif. Quelles spécifications didactiques pour faire apprendre la complexité de la gestion durable de la forêt ?

International audienc

Essai de modelisation de l'organisation spatiale des sols d'une region. Application aux plateaux calcaires bourguignons

45 ref.National audienc