N-cadherin is essential for retinoic acid-mediated cardiomyogenic differentiation in mouse embryonic stem cells.

Contraction forces developed by cardiomyocytes are transmitted across the plasma membrane through end-to-end connections between the myocytes, called intercalated disks, which enable the coordinated contraction of heart muscle. A component of the intercalated disk, the adherens junction, consists of the cell adhesion molecule, N-cadherin. Embryos lacking N-cadherin die at mid-gestation from cardiovascular abnormalities. We have evaluated the role of N-cadherin in cardiomyogenesis using N-cadherin-null mouse embryonic stem (ES) cells grown as embryoid bodies (EBs) in vitro. Myofibrillogenesis, the spatial orientation of myofibers, and intercellular contacts including desmosomes were normal in N-cadherin-null ES cell-derived cardiomyocytes. The effect of retinoic acid (RA), a stage and dose-dependent cardiogenic factor, was assessed in differentiating ES cells. all-trans (at) RA increased the number of ES cell-derived cardiomyocytes by approximately 3-fold (at 3 x 10(-9) M) in wt EBs. However, this effect was lost in N-cadherin-null EBs. In the presence of supplemented at-RA, the emergence of spontaneously beating cardiomyocytes appeared to be delayed and slightly less efficient in N-cadherin-null compared with wt and heterozygous EBs (frequencies of EBs with beating activity at 5 days: 54+/-18% vs. 96+/-0.5%, and 93+/-7%, respectively; peak frequencies of EBs with beating activity: 83+/-8% vs. 96+/-0.5% and 100%, respectively). In conclusion, cardiomyoyctes differentiating from N-cadherin-null ES cells in vitro show normal myofibrillogenesis and intercellular contacts, but impaired responses to early cardiogenic effects mediated by at-RA. These results suggest that N-cadherin may be essential for RA-induced cardiomyogenesis in mouse ES cells in vitro.

From diabetes to heart disease : studies on dyslipidemia-induced B-cell dysfunction, immunomodulation in heart transplantation, and cardiac stem cell therapy

Diabetes is a growing epidemic with devastating human, social and economic impact. It is associated with significant changes in plasma concentrations of lipoproteins. We tested the hypothesis that lipoproteins modulate the function and survival of insulin-secreting cells. We first detected the presence of several receptors that participate in the binding and processing of plasma lipoproteins and confirmed the internalization of fluorescent LDL and HDL particles in insulin-secreting β-cells. Purified human VLDL and LDL particles reduced insulin mRNA levels and β-cell proliferation, and induced a dose-dependent increase in the rate of apoptosis. In mice lacking the LDL receptor, islets showed a dramatic decrease in LDL uptake and were partially resistant to apoptosis caused by LDL. VLDL-induced apoptosis of β-cells involved caspase-3 cleavage and reduction in levels of the c-Jun N-terminal (JNK) Interacting Protein-1 (IB1/JIP-1). In contrast, the pro-apoptotic signaling of lipoproteins was antagonized by HDL particles or by a small peptide inhibitor of JNK. The protective effects of HDL were mediated, in part, by inhibition of caspase-3 cleavage and activation of the protein kinase Akt/PKB. Heart disease is a major cause of morbidity and mortality among patients with diabetes. When heart failure is refractory to medical therapy and cannot be improved by electrical resynchronization, percutaneous angioplasty or coronary graft bypass surgery, heart transplantation remains a "last resort" therapy. Nevertheless, it is limited by the side effects of immunosuppressive drugs and chronic rejection. Localized expression of immunomodulatory genes in the donor organ can create a state of immune privilege within the graft, and was performed in rodent hearts by infecting cells with an adenovirus encoding indoleamine 2,3-dioxygenase (IDO), the rate-limiting enzyme in the catabolism of tryptophane. Other strategies are based on genetic manipulation of dendritic cells (DCs) with immunosuppressive genes and in vitro exposure of DCs to agents that prevent their maturation by inflammatory cytokines. Finally, we used 5-bromo-2'-deoxyuridine, which is incorporated into DNA and diluted with cell division, to identify long-term label retaining cells in the adult rodent heart. The majority of these cells were positive for the stem cell antigen-1 (Sca-1) and negative for the endothelial precursor marker CD31. They formed cardiospheres in vitro and showed differentiation potential into mesenchymal cell lineages. When cultured in cardiomyogenic differentiation medium, they expressed cardiac-specific genes. Taken together, these data provide evidence of slow-cycling stem cells in the rodent heart. Chronic shortage of donor organs opens the way to cardiac stem cell therapy in humans, although the long way from animal experimentation to routine therapy in patients may still take several years. - Du diabète de type 2 à la maladie coronarienne : trois études sur les dysfonctions de la cellule sécrétrice d'insuline induites par les dyslipidémies, l'immunomodulation dans la transplantation cardiaque, et la thérapie par des cellules souches myocardiques. Le diabète de type 2 a pris les dimensions d'une épidémie, avec des conséquences sociales et économiques dont nous n'avons pas encore pris toute la mesure. La maladie s'accompagne souvent d'une dyslipidémie caractérisée par une hypertriglycéridémie, des taux abaissés de cholestérol HDL, et des concentrations de cholestérol LDL à la limite supérieure de ce qui est considéré comme acceptable. L'hypothèse à la base de cette étude est qu'une modification des taux plasmatiques de lipoprotéines pourrait avoir une influence directe sur la cellule β sécrétrice d'insuline en modifiant sa fonction, sa durée de vie et son taux de régénération. Dans un premier temps, nous avons mis en évidence, sur la cellule β, la présence de plusieurs récepteurs impliqués dans la captation des lipoprotéines. Nous avons confirmé la fonctionnalité de ces récepteurs en suivant l'internalisation de LDL et de HDL marqués. En présence de VLDL ou de LDL humains, nous avons observé une diminution de la transcription du gène de l'insuline, une prolifération cellulaire réduite, et une augmentation de l'apoptose, toutes fonctions de la dose et du temps d'exposition. L'apoptose induite par les VLDL passe par une activation de la caspase-3 et une réduction du taux de la protéine IB1/JIP-1 (Islet Brain1/JNK Interacting Protein 1), dont une mutation est associée à une forme monogénique de diabète de type 2. Par opposition, les HDL, ainsi que des peptides inhibiteurs de JNK, sont capables de contrer la cascade pro-apoptotique déclenchée, respectivement, par les LDL et les VLDL. Ces effets protecteurs comprennent l'inhibition du clivage de la caspase-3 et l'activation de la protéine kinase Akt/PKB. En conclusion, les lipoprotéines sont des éléments clés de la survie de la cellule β, et pourraient contribuer au dysfonctionnement observé dans le pancréas endocrine au cours du développement du diabète. La maladie cardiaque, et plus particulièrement la maladie coronarienne, est une cause majeure de morbidité et de mortalité chez les patients atteints de diabète. Plusieurs stratégies sont utilisées quotidiennement pour pallier les atteintes cardiaques: traitements médicamenteux, électromécaniques par resynchronisation électrique, ou communément appelés « interventionnels » lorsqu'ils font appel à l'angioplastie percutanée. La revascularisation du myocarde par des pontages coronariens donne également de très bons résultats dans certaines situations. Il existe toutefois des cas où plus aucune de ces approches n'est suffisante. La transplantation cardiaque est alors la thérapie de choix pour un nombre restreint de patients. La thérapie génique, en permettant l'expression locale de gènes immunomodulateurs dans l'organe greffé, permet de diminuer les réactions de rejet inhérentes à toute transplantation (à l'exception de celles réalisées entre deux jumeaux homozygotes). Nous avons appliqué chez des rongeurs cette stratégie en infectant le coeur greffé avec un adénovirus codant pour l'enzyme indoleamine 2,3-dioxygénase (IDO), une enzyme clé dans le catabolisme du tryptophane. Nous avons procédé de manière identique in vitro en surexprimant IDO dans les cellules dendritiques, dont le rôle est de présenter les antigènes aux lymphocytes Τ du receveur. Des expériences similaires ont été réalisées en traitant les cellules dendritiques avec des substances capables de prévenir, en partie du moins, leur maturation par des agents pro-inflammatoires. Finalement, nous avons exploré une stratégie utilisée couramment en hématologie, mais qui n'en est encore qu'à ses débuts au niveau cardiaque : la thérapie par des cellules souches. En traitant des rongeurs avec un marqueur qui s'incorpore dans l'ADN nucléaire, le 5-bromo- 2'-deoxyuridine, nous avons identifié une population cellulaire se divisant rarement, positive en grande partie pour l'antigène embryonnaire Sca-1 et négative pour le marqueur endothélial CD31. En culture, ces cellules forment des cardiosphères et sont capables de se différencier dans les principaux types tissulaires mésenchymateux. Dans un milieu de differentiation adéquat, ces cellules expriment des gènes cardiomyocytaires. En résumé, ces données confirment la présence chez le rongeur d'une population résidente de précurseurs myocardiques. En addenda, on trouvera deux publications relatives à la cellule β productrice d'insuline. Le premier article démontre le rôle essentiel joué par la complexine dans l'insulino-sécrétion, tandis que le second souligne l'importance de la protéine IB1/JIP-1 dans la protection contre l'apoptose de la cellule β induite par certaines cytokines.

Immunohistochemical and flow cytometric analysis of long-term label-retaining cells in the adult heart.

Cardiac-resident stem/progenitor cells have been identified based on expression of stem cell-associated antigens. However, no single surface marker allows to identify a definite cardiac stem/progenitor cell entity. Hence, functional stem cell markers have been extensively searched for. In homeostatic systems, stem cells divide infrequently and therefore retain DNA labels such as 5-bromo-2'-deoxyuridine, which are diluted with division. We used this method to analyze long-term label-retaining cells in the mouse heart after 14 days of 5-bromo-2'-deoxyuridine administration. Labeled cells were detected using immunohistochemical and flow-cytometric methods after varying chasing periods up to 12 months. Using mathematical models, the observed label dilution could consistently be described in the context of a 2-population model, whereby a population of rapidly dividing cells accounted for an accelerated early decline, and a population of slowly dividing cells accounted for decelerated dilution on longer time scales. Label-retaining cells were preferentially localized in the atria and apical region and stained negative for markers of the major cell lineages present in the heart. Most cells with long-term label-retention expressed stem cell antigen-1 (Sca-1). Sca-1(+)CD31(-) cells formed cell aggregates in culture, out of which lineage-negative (Lin(-))Sca-1(+)CD31(-) cells emerged, which could be cultured for many passages. These cells formed cardiospheres and showed differentiation potential into mesenchymal cell lineages. When cultured in cardiomyogenic differentiation medium, they expressed cardiac-specific genes. In conclusion, recognition of slow-cycling cells provides functional evidence of stem/progenitor cells in the heart. Lin(-)Sca-1(+)CD31(-) cardiac-derived progenitors have a potential for differentiation into cardiomyogenic and mesenchymal cell lineages.

Immediate and delayed effects of subchronic Paraquat exposure during an early differentiation stage in 3D-rat brain cell cultures.

Xenobiotic exposure is a risk factor in the etiology of neurodegenerative disease. It was recently hypothesized that restricted exposure during brain development could predispose for a neurodegenerative disease later in life. As neuroinflammation contributes to progressive neurodegeneration, it is suspected that neurodevelopmental xenobiotic exposure could elicit a neuroinflammatory process, which over time may assume a detrimental character. We investigated the neurotoxic effects of paraquat (PQ) in three-dimensional whole rat brain cell cultures, exposed during an early differentiation stage, comparing immediate effects-directly post exposure-with long-term effects, 20 days after interrupted PQ-administration. Adverse effects and neuroinflammatory responses were assessed by measuring changes in gene- and protein-expression as well as by determining cell morphology changes. Differentiating neural cultures were highly susceptible to PQ and showed neuronal damage and strong astrogliosis. After the 20-day washout period, neurons partially recovered, whereas astrogliosis persisted, and was accompanied by microglial activation of a neurodegenerative phenotype. Our data shows that immediate and long-term effects of subchronic PQ-exposure differ. Also, PQ-exposure during this window of extensive neuronal differentiation led to a delayed microglial activation, of a character that could promote further pro-inflammatory signals that enable prolonged inflammation, thereby fueling further neurodegeneration.

Roles of aldehyde dehydrogenase (ALDH) isoforms and retinoic acids in the growth and differentiation potential of human adult cardiac progenitor cells

Aim: We have studied human adult cardiac progenitor cells (CPCs) based on high aldehyde dehydrogenase activity (ALDH-hi), a property shared by many stem cells across tissues and organs. However, the role of ALDH in stem cell function is poorly known. In humans, there are 19 ALDH isoforms with different biological activities. The isoforms responsible for the ALDH-hi phenotype of stem cells are not well known but they may include ALDH1A1 and ALDH1A3 isoforms, which function in all-trans retinoic acid (RA) cell signaling. ALDH activity has been shown to regulate hematopoietic stem cell function via RA. We aimed to analyze ALDH isoform expression and the role of RA in human CPC function. Methods: Human adult CPCs were isolated from atrial appendage samples from patients who underwent heart surgery for coronary artery or valve disease. Atrial samples were either cultured as primary explants or enzymatically digested and sorted for ALDH activity by FACS. ALDH isoforms were determined by qRT-PCR. Cells were cultured in the presence or absence of the specific ALDH inhibitor DEAB, with or without RA. Induction of cardiac-specific genes in cells cultured in differentiation medium was measured by qRT-PCR. Results: While ALDH-hi CPCs grew in culture and could be expanded, ALDH-low cells grew poorly. CPC isolated as primary explant outgrowths expressed high levels of ALDH1A3 but not of other isoforms. CPCs isolated from cardiospheres expressed relatively high levels of all the 11 isoforms tested. In contrast, expanded CPCs and cardiosphere-derived cells expressed low levels of all ALDH isoforms. DEAB inhibited CPC growth in a dose-dependent manner, whereas RA rescued CPC growth in the presence of DEAB. In differentiation medium, ALDH-hi CPCs expressed approximately 300-fold higher levels of cardiac troponin T compared with their ALDH-low counterparts. Conclusions: High ALDH activity identifies human adult cardiac cells with high growth and cardiomyogenic potential. ALDH1A3 and, possibly, ALDH1A1 isoforms account for high ALDH activity and RA-mediated regulation of CPC growth.

Cell Adhesion Peptide RGDSP and Laminin Support Proliferation and Migration of Postnatal Retinal Stem Cells in a 3D Hydrogel Culture System

Purpose: Retinal stem cells (RSCs) can be isolated from radial glia population of the newborn mouse retina (Angénieux et al., 2006). These RSCs have great capacity to renew and generate neurons including cells differentiated towards the photoreceptor lineage (Mehri-Soussi et al., 2006). However, our published results showed poor integration and survival rate after cell grafting into the retina. The uncontrollable environment of retina seems to be the problem. To bypass this, we are trying to generate hemi-retinal tissue in vitro that can be used for transplantation. Methods: Expanded RSCs were seeded in a mixture of poly-ethylene-glycol (PEG)-polymer-based hydrogels crosslinked by peptides that also serve as substrates for matrix metalloproteinases. Different doses of crosslinker peptides were tested. Several growth factors were studied to stimulate cell proliferation and differentiation. Results: Cells were trapped in hydrogels and cultured in the presence of FGF2 and EGF. Spherical cell clusters indicating proliferation appeared within several days, but there was no cell migration within the gel. We then added cell adhesion molecules integrin ligand RGDSP, or laminin, or a combination of both, into the gel. Cells grown with laminin showed the best proliferation. Cells grown with RGDSP proliferated a few times and then started to spread out. Cells grown with the combination of RGDSP and laminin showed better proliferation than with RGDSP alone and larger spread-outs than with laminin alone. After stimulations with first FGF2 and EGF, and then only FGF2, some cells showed neuronal morphology after 2 weeks. The neuronal population was assessed by the presence of neuronal marker b-tubulin-III. Glial cells were also present. Further characterizations are undergoing. Conclusions: RSC can grow and migrate in 3D hydrogel with the addition of FGF2, EGF, RGDSP and laminin. Further developments are necessary to form a homogenous tissue containing retinal cells.

Brain damage in methylmalonic aciduria: 2-methylcitrate induces cerebral ammonium accumulation and apoptosis in 3D organotypic brain cell cultures.

BACKGROUND: Methylmalonic aciduria is an inborn error of metabolism characterized by accumulation of methylmalonate (MMA), propionate and 2-methylcitrate (2-MCA) in body fluids. Early diagnosis and current treatment strategies aimed at limiting the production of these metabolites are only partially effective in preventing neurological damage. METHODS: To explore the metabolic consequences of methylmalonic aciduria on the brain, we used 3D organotypic brain cell cultures from rat embryos. We challenged the cultures at two different developmental stages with 1 mM MMA, propionate or 2-MCA applied 6 times every 12 h. In a dose-response experiment cultures were challenged with 0.01, 0.1, 0.33 and 1 mM 2-MCA. Immunohistochemical staining for different brain cell markers were used to assess cell viability, morphology and differentiation. Significant changes were validated by western blot analysis. Biochemical markers were analyzed in culture media. Apoptosis was studied by immunofluorescence staining and western blots for activated caspase-3. RESULTS: Among the three metabolites tested, 2-MCA consistently produced the most pronounced effects. Exposure to 2-MCA caused morphological changes in neuronal and glial cells already at 0.01 mM. At the biochemical level the most striking result was a significant ammonium increase in culture media with a concomitant glutamine decrease. Dose-response studies showed significant and parallel changes of ammonium and glutamine starting from 0.1 mM 2-MCA. An increased apoptosis rate was observed by activation of caspase-3 after exposure to at least 0.1 mM 2-MCA. CONCLUSION: Surprisingly, 2-MCA, and not MMA, seems to be the most toxic metabolite in our in vitro model leading to delayed axonal growth, apoptosis of glial cells and to unexpected ammonium increase. Morphological changes were already observed at 2-MCA concentrations as low as 0.01 mM. Increased apoptosis and ammonium accumulation started at 0.1 mM thus suggesting that ammonium accumulation is secondary to cell suffering and/or cell death. Local accumulation of ammonium in CNS, that may remain undetected in plasma and urine, may therefore play a key role in the neuropathogenesis of methylmalonic aciduria both during acute decompensations and in chronic phases. If confirmed in vivo, this finding might shift the current paradigm and result in novel therapeutic strategies.

The long-term survival of in vitro engineered nervous tissue derived from the specific neural differentiation of mouse embryonic stem cells.

Embryonic stem cells (ESCs) offer attractive prospective as potential source of neurons for cell replacement therapy in human neurodegenerative diseases. Besides, ESCs neural differentiation enables in vitro tissue engineering for fundamental research and drug discovery aimed at the nervous system. We have established stable and long-term three-dimensional (3D) culture conditions which can be used to model long latency and complex neurodegenerative diseases. Mouse ESCs-derived neural progenitor cells generated by MS5 stromal cells induction, result in strictly neural 3D cultures of about 120-mum thick, whose cells expressed mature neuronal, astrocytes and myelin markers. Neurons were from the glutamatergic and gabaergic lineages. This nervous tissue was spatially organized in specific layers resembling brain sub-ependymal (SE) nervous tissue, and was maintained in vitro for at least 3.5 months with great stability. Electron microscopy showed the presence of mature synapses and myelinated axons, suggesting functional maturation. Electrophysiological activity revealed biological signals involving action potential propagation along neuronal fibres and synaptic-like release of neurotransmitters. The rapid development and stabilization of this 3D cultures model result in an abundant and long-lasting production that is compatible with multiple and productive investigations for neurodegenerative diseases modeling, drug and toxicology screening, stress and aging research.

3D culture of postnatal retinal stem cells using self assembling polymers

PURPOSE We have previously shown that retinal stem cells (RSCs) can be isolated from the radial glia population of the newborn mouse retina (Angénieux et al., 2006). These RSCs have a great capacity to renew and to generate a large number of neurons including cells differentiated towards the photoreceptor lineage (Mehri-Soussi et al., 2006). However, recent published results from our lab revealed that such cells have a poor integration and survival rate after grafting. The uncontrolled environment of a retina seems to prevent good integration and survival after grafting in vivo. To bypass this problem, we are evaluating the possibility of generating in vitro a hemi-retinal tissue before transplantation. METHODS RSC were expanded and cells passaged <10 were seeded in a solution containing poly-ethylene-glycol (PEG) polymer based hydrogels crosslinked with peptides that are chosen to be substrates for matrix metalloproteinases. Various doses of cross linkers peptides allowing connections between PEG polymers were tested. Different growth factors were studied to stimulate cell proliferation and differentiation. RESULTS Cells survived only in the presence of EGF and FGF-2 and generated colonies with a sphere shape. No cells migrated within the gel. To improve the migration and the repartition of the cells in the gels, the integrin ligand RGDSP was added into the gel. In the presence of FGF-2 and EGF, newly formed cell clusters appeared by cell proliferation within several days, but again no outspreading of cells was observed. No difference was even seen when the stiffness of the hydrogels or the concentration of the integrin ligand RGDSP were changed. However, our preliminary results show that RSCs still form spheres when laminin is entrapped in the gel, but they started to spread out having a neuronal morphology after around 2 weeks. The neuronal population was assessed by the presence of the neuronal marker b-tubulin-III. This differentiation was achieved after successive steps of stimulations including FGF-2 and EGF, and then only FGF-2. Glial cells were also present. Further characterizations are under process. CONCLUSIONS RSC can be grown in 3D. Preliminary results show that neuronal cell phenotype acquisition can be instructed by exogenous stimulations and factors linked to the gel. Further developments are necessary to form a homogenous tissue containing retinal cells.

The retinoid-related orphan receptor RORα promotes keratinocyte differentiation via FOXN1.

RORα is a retinoid-related orphan nuclear receptor that regulates inflammation, lipid metabolism, and cellular differentiation of several non-epithelial tissues. In spite of its high expression in skin epithelium, its functions in this tissue remain unclear. Using gain- and loss-of-function approaches to alter RORα gene expression in human keratinocytes (HKCs), we have found that this transcription factor functions as a regulator of epidermal differentiation. Among the 4 RORα isoforms, RORα4 is prominently expressed by keratinocytes in a manner that increases with differentiation. In contrast, RORα levels are significantly lower in skin squamous cell carcinoma tumors (SCCs) and cell lines. Increasing the levels of RORα4 in HKCs enhanced the expression of structural proteins associated with early and late differentiation, as well as genes involved in lipid barrier formation. Gene silencing of RORα impaired the ability of keratinocytes to differentiate in an in vivo epidermal cyst model. The pro-differentiation function of RORα is mediated at least in part by FOXN1, a well-known pro-differentiation transcription factor that we establish as a novel direct target of RORα in keratinocytes. Our results point to RORα as a novel node in the keratinocyte differentiation network and further suggest that the identification of RORα ligands may prove useful for treating skin disorders that are associated with abnormal keratinocyte differentiation, including cancer.

The role of Notch in the differentiation of CD4⁺ T helper cells.

CD4⁺ T helper cells are playing critical roles in host defense to pathogens and in the maintenance of immune homeostasis. Naïve CD4⁺T cells, upon antigen-specific recognition, receive signals to differentiate into distinct effector T helper cell subsets characterized by their pattern of cytokine production and specific immune functions. A tight balance between these different subsets ensures proper control of the immune response. There is increasing evidence revealing an important role for Notch signaling in the regulation of CD4⁺T helper cell differentiation or function in the periphery. However, the exact mechanisms involved remain unclear and appear contradictory. In this review, we summarize current knowledge and discuss recent advances in the field to reconcile different views on the role of Notch signaling in the differentiation of functional T helper subsets.

Does abdominoplasty with liposuction of the love handles yield a shorter scar? An analysis with abdominal 3D laser scanning.

The aim of this study was to evaluate the combination of abdominoplasty with liposuction of both flanks with regards to length of scar, complications, and patient's satisfaction. A retrospective analysis of 35 patients who underwent esthetic abdominoplasty at our institution between 2002 and 2004 was performed. Thirteen patients underwent abdominoplasty with liposuction of both flanks, 22 patients underwent conventional abdominoplasty. Liposuction of the flanks did not increase the rate of complications of the abdominoplasty procedures. We found a tendency toward shorter scars in patients who underwent abdominoplasty combined with liposuction of the flanks. Implementation of 3-dimensional laser surface scanning to objectify the postoperative outcomes, documented a comparable degree of flatness of the achieved body contouring in both procedures. 3-dimensional laser surface scanning can be a valuable tool to objectify assessment of postoperative results.

Monocyte differentiation toward regulatory dendritic cells is not affected by respiratory syncytial virus-induced inflammatory mediators.

Airway epithelial cells were shown to drive the differentiation of monocytes into dendritic cells (DCs) with a suppressive phenotype. In this study, we investigated the impact of virus-induced inflammatory mediator production on the development of DCs. Monocyte differentiation into functional DCs, as reflected by the expression of CD11c, CD123, BDCA-4, and DC-SIGN and the capacity to activate T cells, was similar for respiratory syncytial virus (RSV)-infected and mock-infected BEAS-2B and A549 cells. RSV-conditioned culture media resulted in a partially mature DC phenotype, but failed to up-regulate CD80, CD83, CD86, and CCR7, and failed to release proinflammatory mediators upon Toll-like receptor (TLR) triggering. Nevertheless, these DCs were able to maintain an antiviral response by the release of Type I IFN. Collectively, these data indicate that the airway epithelium maintains an important suppressive DC phenotype under the inflammatory conditions induced by infection with RSV.

IB1/JIP-1 controls JNK activation and increased during prostatic LNCaP cells neuroendocrine differentiation.

The scaffold protein Islet-Brain1/c-Jun amino-terminal kinase Interacting Protein-1 (IB1/JIP-1) is a modulator of the c-Jun N-terminal kinase (JNK) activity, which has been implicated in pleiotrophic cellular functions including cell differentiation, division, and death. In this study, we described the presence of IB1/JIP-1 in epithelium of the rat prostate as well as in the human prostatic LNCaP cells. We investigated the functional role of IB1/JIP-1 in LNCaP cells exposed to the proapoptotic agent N-(4-hydroxyphenyl)retinamide (4-HPR) which induced a reduction of IB1/JIP-1 content and a concomittant increase in JNK activity. Conversely, IB1/JIP-1 overexpression using a viral gene transfer prevented the JNK activation and the 4-HPR-induced apoptosis was blunted. In prostatic adenocarcinoma cells, the neuroendocrine (NE) phenotype acquisition is associated with tumor progression and androgen independence. During NE transdifferentiation of LNCaP cells, IB1/JIP-1 levels were increased. This regulated expression of IB1/JIP-1 is secondary to a loss of the neuronal transcriptional repressor neuron restrictive silencing factor (NRSF/REST) function which is known to repress IB1/JIP-1. Together, these results indicated that IB1/JIP-1 participates to the neuronal phenotype of the human LNCaP cells and is a regulator of JNK signaling pathway.