Le coeur des ARN non codants - Un long chemin à découvrir [In the heart of noncoding RNA: a long way to go].

The identification and characterization of long noncoding RNA in a variety of tissues represent major achievements that contribute to our understanding of the molecular mechanisms controlling gene expression. In particular, long noncoding RNA play crucial roles in the epigenetic regulation of the adaptive response to environmental cues via their capacity to target chromatin modifiers to specific locus. In addition, these transcripts have been implicated in controlling splicing, translation and degradation of messenger RNA. Long noncoding RNA have also been shown to act as decoy molecules for microRNA. In the heart, a few long noncoding RNA have been demonstrated to regulate cardiac commitment and differentiation during development. Furthermore, recent findings suggest their involvement as regulators of the pathophysiological response to injury in the adult heart. Their high cellular specificity makes them attractive target molecules for innovative therapies and ideal biomarkers

Caractérisation fonctionnelle des ARN nucléolaires U8 et U13 et des microARN du cluster miR-379/410

Ces dernières années, le monde du non-codant a connu une formidable expansion grâce à la découverte de nouveaux petits ARNnc régulateurs chez les mammifères. Certains d'entre eux présentent des caractéristiques encore jamais observées puisqu'ils peuvent être tissu-spécifiques, répétés en tandem ou soumis à l'empreinte génomique parentale. Cependant, la fonction de beaucoup d'entre eux reste à ce jour inconnue. Nos travaux ont porté, par des approches de perte de fonction, sur la caractérisation fonctionnelle d'ARN appartenant à deux grandes familles de petits ARNnc : les ARN nucléolaires à boîtes C/D (snoARN C/D) et les microARN. Les snoARN C/D sont connus pour participer à la biogenèse des ARN ribosomiques (ARNr) et du petit ARN du spliceosome U6 (snARN U6). Afin d'étudier la fonction de deux snoRNP humaines, U8 et U13, nous avons développé une nouvelle technique d'inactivation de ces ARN C/D dans des cellules en culture, basées sur l'utilisation d'oligonucléotides antisens modifiés appelés LNA (Locked Nucleic Acids). Nous avons ainsi pu démontrer, pour la première fois, l'importance de snoRNP humaines pour la croissance cellulaire ainsi que leur rôle éventuel de chaperon dans des conditions de stress cellulaire. De plus, nous avons montré pour U8 une implication dans la biogenèse des ARN ribosomiques. Ces travaux constituent donc une première étape dans l'étude systématique des nombreux snoARN de mammifères dont la fonction est encore inconnue. Les microARN sont des régulateurs de l'expression des gènes à un niveau post-transcriptionnel. Nos travaux portent sur le cluster de microARN murin miR-379/410, codant pour 54 microARN et représentant près de 10% des microARN murins identifiés à ce jour. Il est situé au locus Dlk1-Dio3, une région ayant la particularité d'être soumise à l'empreinte génomique parentale, un mécanisme épigénétique qui conduit à une expression monoallélique des gènes, et ce de manière strictement dépendante de l'origine parentale du chromosome qui porte les allèles. Afin d'étudier la fonction des microARN du cluster miR-379/410, nous avons généré une lignée de souris knockout pour ce cluster. Nos premiers résultats montrent que ces microARN sont importants pour la viabilité post-natale des souris ainsi que pour leur croissance. Ces travaux constituent une avancée importante dans la compréhension du rôle des miARN chez les mammifères.In the past few years, non-coding world has greatly expanded thanks to the discovery of new small regulatory ncRNAs in mammals. Some of them have particular features, as they may be tissue-specific, repeated in tandem or subjected to genomic imprinting. However, the function of many of them remains unknown. Our work has focused, using loss of function approaches, on the functional characterization of RNAs from two large families of small ncRNAs: C/D box small nucleolar RNAs (snoRNAs) and microRNAs. C/D snoRNAs are known to participate in the biogenesis of ribosomal RNAs (rRNAs) and small spliceosome U6 RNA (U6 snRNA). To investigate the function of two human snoRNPs, U8 and U13, we developed a new inactivation technique of C/D RNAs in cultured cells, using modified antisense oligonucleotides called LNA (Locked Nucleic Acids). We were able to demonstrate, for the first time, the importance of human snoRNPs for the cell growth and their possible role as a chaperone under conditions of cellular stress. Furthermore, we showed the involvement of U8 in the biogenesis of ribosomal RNAs. Thus, this work is a first step in the systematic study of many mammalian snoRNAs whose function is still unknown. MicroRNAs are regulators of gene expression at a posttranscriptional level. Our work focused on the cluster of murine microRNAs miR-379/410, encoding 54 miRNAs that represent nearly 10% of murine miRNAs identified to date. It is located in the DLK1-DIO3 locus, a region subjected to genomic imprinting, an epigenetic mechanism that leads to monoallelic expression of genes dependent on the parental origin of chromosome that carries the alleles. To study the function of microRNAs cluster miR-379/410, we generated a knockout mouse line for that cluster. Our first results show that these miRNAs are important for mice postnatal viability as well as for their growth. This work represents an important advance in understanding miRNAs roles in mammals

Pour les tics et tocs, serait-ce SLITRK1 ?

Type 2 diabetes is characterized by two major defects: a dysregulation of pancreatic hormone secretion (quantitative and qualitative--early phase, pulsatility--decrease of insulin secretion, increase in glucagon secretion), and a decrease in insulin action on target tissues (insulin resistance). The defects in insulin action on target tissues are characterized by a decreased in muscle glucose uptake and by an increased hepatic glucose production. These abnomalities are linked to several defects in insulin signaling mechanisms and in several steps regulating glucose metabolism (transport, key enzymes of glycogen synthesis or of mitochondrial oxidation). These postreceptors defects are amplified by the presence of high circulating concentrations of free fatty acids. The mechanisms involved in the "diabetogenicity" of long-chain fatty acids are reviewed in this paper. Indeed, elevated plasma free fatty acids contribute to decrease muscle glucose uptake (mainly by reducing insulin signaling) and to increase hepatic glucose production (stimulation of gluconeogenesis by providing cofactors such as acetyl-CoA, ATP and NADH). Chronic exposure to high levels of plasma free fatty acids induces accumulation of long-chain acyl-CoA into pancreatic beta-cells and to the death of 50% of beta-cell by apoptosis (lipotoxicity)

Terapia génica: desde los extractos y las píldoras a las pociones de ADN

La terapia génica es un tratamiento alternativo a los abordajes farmacológicos, quirúrgicos y de índole convencional que se está desarrollando tanto a nivel experimental como clínico. En esta revisión, más allá de mencionar los avances y presentar un panorama del tema en el área biomédica, se pretende ampliar el concepto de ADN, desde su función como reservorio fundamental de información para la síntesis de proteínas hasta sus acciones “como fármaco”. Se espera que el ADN encapsulado en vectores o directamente aplicado al tejido, cumpla la función que el gen defectuoso no puede realizar mediante su reemplazo, o impida que un gen desregulado permanezca activo, a través de mecanismos de interferencia. Estos objetivos no solo están dirigidos al tratamiento de pacientes de diferentes edades, sino también de individuos aún no natos, como lo evidencian numerosos abordajes experimentales de terapia génica intrauterina. Actualmente existen varios productos comerciales surgidos en el contexto de la terapia génica. Una vez que este tipo de tratamiento sortee aquellos aspectos que todavía constituyen importantes factores de riesgo, se establezcan acuerdos éticos y se equilibren los costos de las intervenciones, constituirá una alternativa a los métodos convencionales para tratar ciertas enfermedades. El ADN (y el ARN) se presentan como los futuros fármacos en acción de las próximas décadas.Abstract Gene therapy is a treatment that offers an alternative to pharmacological, surgical and conventional approaches that is being developed at an experimental and clinical level. In this review, apart from mentioning advances and presenting an overview of the subject in the biomedical field, our intention is to extend the concept of DNA. DNA is the store of information for protein synthesis and today it is also “a drug”. It is expected for the DNA embedded in vectors or directly applied to tissue to perform the function that the defective gene cannot perform by means of its replacement, or to prevent that gene from remaining active through mechanisms of interference. This is not only aimed at the treatment of patients of different ages but also unborn children, as it has been proved by several experimental approaches of intrauterine gene therapy. Currently there are several commercially available products that have emerged from the context of gene therapy. Once those aspects that still represent important risk factors are overcome, ethical agreements are reached and the costs of the interventions are leveled out, this type of treatment will constitute an alternative to conventional methods to treat certain diseases. DNA (and RNA) are proposed as the future drugs for the following decades.Fil: Santalla, Manuela. Universidad Nacional del Noroeste de la Provincia de Buenos Aires. Departamento de Ciencias Básicas y Experimentales; ArgentinaFil: Fesser, E.. Universidad Nacional del Noroeste de la Provincia de Buenos Aires. Departamento de Ciencias Básicas y Experimentales; ArgentinaFil: Asad, Antonela Sofía. Universidad Nacional del Noroeste de la Provincia de Buenos Aires. Departamento de Ciencias Básicas y Experimentales; ArgentinaFil: Acosta, D.. Universidad Nacional del Noroeste de la Provincia de Buenos Aires. Departamento de Ciencias Básicas y Experimentales; ArgentinaFil: Harnichar, E.. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnológico la Plata. Centro de Investigaciones Cardiovasculares "Dr. Horacio Eugenio Cingolani"; Argentina. Universidad Nacional de La Plata; ArgentinaFil: Ferrero, Paola Viviana. Universidad Nacional del Noroeste de la Provincia de Buenos Aires. Departamento de Ciencias Básicas y Experimentales; Argentina. Universidad Nacional de La Plata; Argentin