G1 phase arrest by the phosphatidylinositol 3-kinase inhibitor LY 294002 is correlated to up-regulation of p27Kip1 and inhibition of G1 CDKs in choroidal melanoma cells

AbstractWe have investigated the effect of the flavonoid derivative LY 294002, a potent and selective phosphatidylinositol 3-kinase inhibitor, on cell cycle progression in human choroidal melanoma cells. We demonstrate that LY 294002 induces a specific G1 block in asynchronously growing cells leading to an almost complete inhibition of cell proliferation after three days of treatment. When melanoma cells are released from a nocodazole-induced G2/M block, LY 294002 is shown to delay and greatly restrain the G1/S transition. The inhibitor is able to exert its action as long as it is added during the G1 progression and before the cells enter in S phase. We report that the LY 294002-induced G1 arrest is closely correlated to inhibition of CDK4 and CDK2 activities leading to the impairment of pRb phosphorylation which normally occurs during G1 progression. While the inhibition of CDK4 may be attributed at least in part to the decline in CDK4 protein level, CDK2 activity reduction is rather due to the up-regulation of the CDK inhibitor p27Kip1 and to its increased association to CDK2

Histoire de l'Amérique septentrionale contenant l'histoire des Abenaguis, la paix générale dans toute l'Amérique septentrionale, sous le gouvernement de Monsieur le comte de Frontenac & Monsieur le Chevalier de Callieres, pendant laquelle des nations éloigné es de six cens lieues de Québec s'assemblerent à Montréal

Histoire De L'Amerique Septentrionale. Contenan

Increased mitochondrial NADPH oxidase 4 (NOX4) expression in aging is a causative factor in aortic stiffening

Aging is characterized by increased aortic stiffness, an early, independent predictor and cause of cardiovascular disease. Oxidative stress from excess reactive oxygen species (ROS) production increases with age. Mitochondria and NADPH oxidases (NOXs) are two major sources of ROS in cardiovascular system. We showed previously that increased mitochondrial ROS levels over a lifetime induce aortic stiffening in a mouse oxidative stress model. Also, NADPH oxidase 4 (NOX4) expression and ROS levels increase with age in aortas, aortic vascular smooth muscle cells (VSMCs) and mitochondria, and are correlated with age-associated aortic stiffness in hypercholesterolemic mice. The present study investigated whether young mice (4 months-old) with increased mitochondrial NOX4 levels recapitulate vascular aging and age-associated aortic stiffness. We generated transgenic mice with low (Nox4TG605; 2.1-fold higher) and high (Nox4TG618; 4.9-fold higher) mitochondrial NOX4 expression. Young Nox4TG618 mice showed significant increase in aortic stiffness and decrease in phenylephrine-induced aortic contraction, but not Nox4TG605 mice. Increased mitochondrial oxidative stress increased intrinsic VSMC stiffness, induced aortic extracellular matrix remodeling and fibrosis, a leftward shift in stress-strain curves, decreased volume compliance and focal adhesion turnover in Nox4TG618 mice. Nox4TG618 VSMCs phenocopied other features of vascular aging such as increased DNA damage, increased premature and replicative senescence and apoptosis, increased proinflammatory protein expression and decreased respiration. Aortic stiffening in young Nox4TG618 mice was significantly blunted with mitochondrial-targeted catalase overexpression. This demonstration of the role of mitochondrial oxidative stress in aortic stiffness will galvanize search for new mitochondrial-targeted therapeutics for treatment of age-associated vascular dysfunction

ETUDE IRM DES MODIFICATIONS DYNAMIQUES DE LA TRAVERSEE CERVICO-THORACO-BRACHIALE DANS UNE POPULATION SYMPTOMATIQUE ET ASYMPTOMATIQUE

GRENOBLE1-BU Médecine pharm. (385162101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Apport de l'échographie dans la prise en charge diagnostique des lésions traumatiques occultes du poignet

LILLE2-BU Santé-Recherche (593502101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

IMPLICATION DE L'ACTIVITE PHOSPHOINOSITIDE 3-KINASE DANS LA PROLIFERATION DES CELLULES MUSCULAIRES LISSES D'AORTE DE PORC - IDENTIFICATION D'UNE PHOSPHOINOSITIDE 3-KINASE NUCLEAIRE DE TYPE

LA PROLIFERATION DES CELLULES MUSCULAIRES LISSES (CMLS) JOUE UN ROLE CRUCIAL DANS LA PATHOGENESE DE L'ATHEROSCLEROSE ET DE LA RESTENOSE. TOUTEFOIS, LES MECANISMES MOLECULAIRES RESPONSABLES DE CETTE CROISSANCE CELLULAIRE SONT PEU CONNUS. RECEMMENT, L'ACTIVITE PHOSPHOINOSITIDE 3-KINASE (PI3K) A ETE IMPLIQUEE DANS LES VOIES DE TRANSDUCTION DU SIGNAL MITOGENE. CETTE LIPIDE KINASE PHOSPHORYLE LA POSITION D3 DU NOYAU INOSITOL DES PHOSPHOINOSITIDES POUR PRODUIRE LES 3-PHOSPHOINOSITIDES (3-PIS), SECONDS MESSAGERS INTRACELLULAIRES. NOUS NOUS SOMMES INTERESSES A LA RELATION ENTRE ACTIVITE PI3K ET CONTROLE DU CYCLE CELLULAIRE DANS DES CMLS ISOLEES D'AORTE DE PORC. NOUS AVONS MONTRE QUE LE LY294002 ET LA WORTMANNINE, INHIBITEURS DE PI3K, INHIBENT LA SYNTHESE D'ADN INDUITE PAR LE SERUM. DES ETUDES DE CINETIQUE ONT REVELE UN BLOCAGE DE LA PROLIFERATION EN PHASE G 1 TARDIVE, ENVIRON 6 H AVANT LA TRANSITION G 1/S (POINT PI3K). L'ARRET DU CYCLE EST CORRELE A UNE REDUCTION DE L'EXPRESSION ET DE L'ACTIVITE DE LA KINASE DEPENDANTE DES CYCLINES, CDK2, ET AU MAINTIEN DE L'EXPRESSION DE P27 K I P L, INHIBITEUR DE CDKS. UN TRAVAIL PRELIMINAIRE SEMBLE INDIQUER QUE LES VOIES MITOGEN-ACTIVATED PROTEIN KINASES ET P70S6 KINASE SONT EN AVAL DU POINT PI3K. NOUS AVONS AUSSI RECHERCHE L'EXISTENCE D'UNE PI3K NUCLEAIRE DANS LES CMLS. NOUS AVONS MONTRE LA PRESENCE D'UNE PI3K DE TYPE , DE 117 KDA, CAPABLE DE PHOSPHORYLER UN STOCK INTRANUCLEAIRE DE PI(4,5)P 2 POUR FORMER DU PI(3,4,5)P 3. CETTE ENZYME, SENSIBLE AUX INHIBITEURS DE PI3K, EST SPECIFIQUEMENT ACTIVEE PAR LE GTPS ET DEPEND PARTIELLEMENT DES PROTEINES G 1/G 0. ENFIN, NOUS AVONS IDENTIFIE DEUX CIBLES POTENTIELLES DU PI(3,4,5)P 3 NUCLEAIRE : LES SERINE/THREONINE KINASES PKC ET AKT. NOS RESULTATS MONTRENT UN ROLE CRITIQUE DE L'ACTIVITE PI3K DANS LA PROLIFERATION DES CMLS ET L'EXISTENCE D'UN METABOLISME NUCLEAIRE DES 3-PIS. ILS OUVRENT DE NOUVELLES PERSPECTIVES THERAPEUTIQUES DANS LE TRAITEMENT DE LA RESTENOSE ET DE L'ATHEROSCLEROSE.TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Dewar valence isomer, a biologically relevant DNA photoproduct produced by combined exposure to UVB and UVA

International audienc

Percutaneous absorption and metabolism of [14C]-ethoxycoumarin in a pig ear skin model

International audienceThe biotransformation of chemicals by the skin can be a critical determinant of systemic exposure in humans following dermal absorption. Pig ear skin, which closely resembles human skin, is a candidate ex vivo alternative model for the investigation of xenobiotics penetration and metabolism. We developed an ex vivo pig ear skin model and explored its absorption, diffusion and metabolic capabilities using the model compound 14C-ethoxycoumarin (7-EC). Experimentations were undertaken on pig ear skin explants after application of various 14C-EC doses. Diffusion was quantified as well as the production of 7-EC metabolites resulting from phases I and II enzyme activities, using radio-HPLC. After 48 h, most of the radioactivity was absorbed and was recovered in culture media (70%) or in the skin itself (10%). 7-EC metabolites were identified as 7-hydroxycoumarin (OH–C) and the corresponding sulfate (S–O–C) and glucuronide (G–O–C) conjugates. Their formation followed Michaelis–Menten kinetics with saturation reached around 100 μM of 7-EC. Results demonstrate that dermal absorption as well as phases I and II enzymatic activities of pig skin are both functional. This model should represent a valuable alternative for the study of the transdermal exposure to chemicals, combining a functional dermal barrier and active biotransformation capabilities