CSN5 binds to misfolded CFTR and promotes its degradation

AbstractCystic fibrosis is mainly caused by mutations that interfere with the biosynthetic folding of the cystic fibrosis transmembrane conductance regulator (CFTR) protein. The aim of this study was to find cellular proteins interacting with CFTR and regulating its processing. We have used a genetic screen in yeast to identify such proteins and identified CSN5 that interacted with the third cytoplasmic loop of CFTR. CSN5 is the 5th component of the COP9 signalosome, a complex of eight subunits that shares significant homologies to the lid subcomplex of the 26S proteasome and controls the stability of many proteins. The present study shows that CSN5 associates with the core-glycosylated form of CFTR and suggests that this association targets misfolded CFTR to the degradative pathway. Identifying CSN5 as a new component of the degradative pathway is an important step towards the goal of unraveling the sorting between misfolded and correctly folded CFTR proteins

Modelling the properties of liquid foods for use of process flowsheeting simulators: Application to milk concentration

In this paper, a modelling approach for liquid food products in a chemical process simulator is proposed from the flowsheeting methodology widely used for chemical processes. The focus is set on dairy concentration processes, in which milk is defined as a mixture of water and four dry matter components (fat, proteins, carbohydrates, minerals) modelled as “pseudo-components” in a conventional simulator which has been adapted to take into account the behaviour of the liquid food product considered. The significant properties of milk (heat capacity, boiling point elevation, thermal conductivity, density, viscosity, surface tension) are modelled with empirical models found in the literature and implemented in the simulator. In order to validate the approach, an industrial milk evaporation process and a pilot-scale evaporator are modelled and simulated. The results are compared with industrial and experimental results respectively, and show a good agreement with the industrial process. However improvements are needed in modelling the pilot scale evaporator. The proposed approach is generic enough to be extended to other liquid foods

COMMD1-Mediated Ubiquitination Regulates CFTR Trafficking

The CFTR (cystic fibrosis transmembrane conductance regulator) protein is a large polytopic protein whose biogenesis is inefficient. To better understand the regulation of CFTR processing and trafficking, we conducted a genetic screen that identified COMMD1 as a new CFTR partner. COMMD1 is a protein associated with multiple cellular pathways, including the regulation of hepatic copper excretion, sodium uptake through interaction with ENaC (epithelial sodium channel) and NF-kappaB signaling. In this study, we show that COMMD1 interacts with CFTR in cells expressing both proteins endogenously. This interaction promotes CFTR cell surface expression as assessed by biotinylation experiments in heterologously expressing cells through regulation of CFTR ubiquitination. In summary, our data demonstrate that CFTR is protected from ubiquitination by COMMD1, which sustains CFTR expression at the plasma membrane. Thus, increasing COMMD1 expression may provide an approach to simultaneously inhibit ENaC absorption and enhance CFTR trafficking, two major issues in cystic fibrosis

COMMD1-Mediated Ubiquitination Regulates CFTR Trafficking

The CFTR (cystic fibrosis transmembrane conductance regulator) protein is a large polytopic protein whose biogenesis is inefficient. To better understand the regulation of CFTR processing and trafficking, we conducted a genetic screen that identified COMMD1 as a new CFTR partner. COMMD1 is a protein associated with multiple cellular pathways, including the regulation of hepatic copper excretion, sodium uptake through interaction with ENaC (epithelial sodium channel) and NF-kappaB signaling. In this study, we show that COMMD1 interacts with CFTR in cells expressing both proteins endogenously. This interaction promotes CFTR cell surface expression as assessed by biotinylation experiments in heterologously expressing cells through regulation of CFTR ubiquitination. In summary, our data demonstrate that CFTR is protected from ubiquitination by COMMD1, which sustains CFTR expression at the plasma membrane. Thus, increasing COMMD1 expression may provide an approach to simultaneously inhibit ENaC absorption and enhance CFTR trafficking, two major issues in cystic fibrosis

Leber Congenital Amaurosis: Comprehensive Survey of the Genetic Heterogeneity, Refinement of the Clinical Definition, and Genotype-Phenotype Correlations as a Strategy for Molecular Diagnosis

Communicated by Jean-Claude Kaplan Leber congenital amaurosis (LCA) is the earliest and most severe form of all inherited retinal dystrophies, responsible for congenital blindness. Disease-associated mutations have been hitherto reported in seven genes. These genes are all expressed preferentially in the photoreceptor cells or the retinal pigment epithelium but they are involved in strikingly different physiologic pathways resulting in an unforeseeable physiopathologic variety. This wide genetic and physiologic heterogeneity that could largely increase in the coming years, hinders the molecular diagnosis in LCA patients. The genotyping is, however, required to establish genetically defined subgroups of patients ready for therapy. Here, we report a comprehensive mutational analysis of the all known genes in 179 unrelated LCA patients, including 52 familial and 127 sporadic (27/127 consanguineous) cases. Mutations were identified in 47.5% patients. GUCY2D appeared to account for most LCA cases of our series (21.2%), followed by CRB1 (10%), RPE65 (6.1%), RPGRIP1 (4.5%), AIPL1 (3.4%), TULP1 (1.7%), and CRX (0.6%). The clinical history of all patients with mutations was carefully revisited to search for phenotype variations. Sound genotype-phenotype correlations were found that allowed us to divide patients into two main groups. The first one includes patients whose symptoms fit the traditional definition of LCA, i.e., congenital or very early cone-rod dystrophy, while the second group gathers patients affected with severe yet progressive rodcone dystrophy. Besides, objective ophthalmologic data allowed us to subdivide each group into two subtypes. Based on these findings, we have drawn decisional flowcharts directing the molecular analysis of LCA genes in a given case. These flowcharts will hopefully lighten the heavy task of genotyping new patients but only if one has access to the most precise clinical history since birth

Rôle des interactions moléculaires dans le processus de maturation de la protéine CFTR (implications de CSN5 et de la voie du signalosome)

La mucoviscidose, maladie génétique la plus fréquente dans les populations d origine caucasienne, résulte de mutations dans le gène codant la protéine CFTR (Cystic Fibrosis Transmembrane conductance Regulator). La plus fréquente des mutations de CFTR est une délétion du codon correspondant à la phénylalanine 508 (F508del) qui est à l origine d un adressage défectueux et d une fonction altérée de la protéine. L objectif de ce travail a été d identifier des protéines interagissant avec CFTR et pouvant jouer un rôle dans son adressage, son recyclage à la membrane ou sa fonction. Pour cela, un crible double hybride de levure a été réalisé avec la troisième boucle cytoplasmique de CFTR comme appât. Ce test a permis d identifier 14 nouveaux partenaires dans la levure. L interaction de CFTR avec quatre d entre eux a ensuite été confirmée dans des modèles cellulaires humains. Le travail a été orienté ensuite vers une étude approfondie du rôle de l un de ces partenaires, CSN5, dans le processus de maturation de CFTR. Nous avons montré que CSN5, cinquième sous-unité du signalosome, interagit avec la forme mal repliée de CFTR et l envoie vers la dégradation via le protéasome. Notre étude permet de proposer un modèle de dégradation de CFTR où le signalosome constitue un nouveau point de contrôle du processus de maturation de CFTR. Par ailleurs, nous avons montré dans deux systèmes cellulaires que CFTR était NEDDylé, cette nouvelle modification post-traductionnelle étant dépendante de CSN5. Dans un dernier temps, nous avons étudié le rôle de CSN5 dans la régulation de gènes dans un contexte CF grâce à une puce ADN. L extinction de CSN5 dans des cellules épithéliales bronchiques IB3-1 (F508del/W1282X), entraîne une dérégulation de près de 400 gènes dont nombre sont impliqués dans les voies de l inflammation et de réponse au stress. Au niveau protéique, CSN5 est également impliqué dans la régulation négative de la production de cytokines pro-inflammatoires IL-8 via une stimulation par le TNFa. CSN5 interagit avec une variété de molécules de signalisation en régulant leur stabilité et peut également diriger les cellules vers une voie de réponse au stress (UPR) ou l apoptose. Identifier CSN5 comme un composant de la voie de dégradation est une étape importante dans la compréhension du processus de maturation de la protéine CFTR, impliquant potentiellement une étape de NEDDylation. De plus, CSN5 pourrait être impliqué dans le mécanisme de réponse inflammatoire exacerbée observé chez les patients CF.Cystic Fibrosis is the most common genetic disease in Caucasians and is caused by mutations in the CFTR gene (Cystic Fibrosis Transmembrane conductance Regulator). The most frequent mutation is the deletion of Phenylalanine 508 (F508del) that produces a protein with processing and functional defects. The aim of our work was to identify new CFTR partners, implicated in its processing, recycling or function. We realized a yeast two hybrid screening with the third cytoplasmic loop of CFTR as a bait. We identified 14 new CFTR partners in yeast with this approach. The interaction between CFTR and 4 of these proteins was confirmed in human cellular models. We then studied the role of CSN5 in CFTR processing. We showed that CSN5, the fifth subunit of signalosome, associates with misfolded CFTR and targets it to the proteasome-dependant degradation pathaway. We propose an additional degradation pathway of CFTR implicating the signalosome as a new processing checkpoint. We also showed in two different cellular models that CFTR is NEDDylated and that this new post-translational modification is CSN5-dependant. In a second study, we investigated the role of CSN5 in gene regulation in CF cells using DNA microarrays. IB3-1 cells (F508del/W1282X) treated with siCSN5 presented a deregulation of more than 400 genes, most of them implicated in inflammatory and stress response pathways. CSN5 was also found to be a negative regulator of pro-inflammatory cytokine IL-8 production in response to TNFa stimulation. CSN5 interacts with a variety of signalling molecules and regulates their stability, and is also a key molecule that directs cells towards apoptosis or stress response (UPR). Identifying CSN5 as a new component of the network of the degradative pathway is an important step towards the goal of unraveling the sorting between misfolded and correctly folded CFTR proteins, possibly implying a NEDDYlation step. Moreover, CSN5 could be considered in the mechanisms of excessive inflammatory response observed in CF patients.PARIS12-CRETEIL BU Multidisc. (940282102) / SudocSudocFranceF

The implications of the European Neighbourhood Policy (ENP) on the EU-Russian Strategic Partnership

The 'shared neighbourhood' is a common challenge for both the future of the EU-Russian Strategic Partnership and the new European Neighbourhood Policy. Whether in the Strategic Partnership or in the European Neighbourhood Policy, the Russian Federation is considered by the European Union as a key partner. Nevertheless, the EU policy towards Russia is unclear and the relationship between both remains highly ambiguous. The actual 'strategic partnership' is still very fragile in spite of recent declarations and developments. The main problem is the security partnership: EU and Russia have to co-operate in the field of security (soft and hard security) and stability but they do not know how. The implementation of the European Neighbourhood Policy in 2005 might be a chance for the EU to give more substance and more consistency to their policy towards the new neighbours. But on the contrary, the ENP seems to intensify the constraints. The ENP lacks coherence with respect to the existing EU -Russian Strategic partnership: Firstly, the place of Russia in the ENP is nothing but clear. Russia is 'half in half out'. Secondly, the Russian factor is largely under estimated in the EU policies towards the new neighbours. Thirdly, the role imagined for Russia in the implementation of the secure and stable area is not clarified

Sea surface temperature impact on diurnal cycle and seasonal evolution of the Guinea Coast Rainfall in boreal spring and summer

International audienceERA5 reanalyses and observations of convective clouds and precipitation are used over the northern Gulf of Guinea between 7W and 3E to study the influence of ocean surface temperature and land-sea temperature gradient on Guinea Coast Rainfall (GCR) in boreal spring and summer. Seasonal composites are calculated around two dates indexing the onset ( T ref ) and demise ( T end ) of the GCR: T ref corresponds to the emergence of the equatorial upwelling in boreal spring, which “pushes” the zonal precipitation belt northward against the Guinea coast. T end characterizes the emergence of the coastal upwelling in July, which is known to coincide with the beginning of the “little dry season” that lasts until September. Along the Guinea Coast, the diurnal cycle of the air-sea temperature gradient controls precipitation through the land-sea breeze, which explains why precipitation reaches its maximum around noon over the ocean, and in the late afternoon over the continent. The emergence of the Guinea Coast upwelling in July induces a weakening of southerlies on a seasonal scale, and a weaker land breeze on a diurnal scale: it induces a decrease in the convergence of humidity transport across the coast and in coastal oceanic precipitation. Therefore, the GCR is seasonally controlled by the latitude of the maximum tropospheric water vapor content and the annual cycle of the West African Monsoon, but the ocean surface temperature is responsible for the abruptness of its onset via the intensification of the equatorial upwelling around the end of May, and possibly of its demise as well via the emergence of the coastal upwelling by early July

Diurnal cycle and seasonal evolution of the West African monsoon in thesouthern coastal region

International audienceThe representation of the diurnal cycle is an identified problem for the West African Monsoon forecasts, inparticular for the intraseasonal variability : models are known for their poor representation of clouds, whichhas a strong impact on solar radiation and surface energy balance, and therefore on the diurnal cycle in theatmospheric boundary layer. Since the latter is connected to the triggering of convection, this flaw leads to anunrealistic representation of humidity gradient between the Gulf of Guinea and the Sahel, moisture transportand precipitation. In this study, the Guinean Coastal Rainfall is analysed from the end of the oceanic phaseuntil the beginning of the Sahelian phase of the monsoon in 2008-2015, with reanalyses (ECMWF ERA5) andsatellite observations for clouds (MSG), precipitation (TRMM B42) and surface wind (ASCAT). The sea breeze/ land breeze alternation and its connection with the low-level wind divergence and surface temperature gradientwere found to strongly dominate the diurnal signal. Reanalyses and observations were then compared to betterunderstand the poor representation of precipitation in the mod

Diurnal cycle and seasonal evolution of the West African monsoon in thesouthern coastal region

International audienceThe representation of the diurnal cycle is an identified problem for the West African Monsoon forecasts, inparticular for the intraseasonal variability : models are known for their poor representation of clouds, whichhas a strong impact on solar radiation and surface energy balance, and therefore on the diurnal cycle in theatmospheric boundary layer. Since the latter is connected to the triggering of convection, this flaw leads to anunrealistic representation of humidity gradient between the Gulf of Guinea and the Sahel, moisture transportand precipitation. In this study, the Guinean Coastal Rainfall is analysed from the end of the oceanic phaseuntil the beginning of the Sahelian phase of the monsoon in 2008-2015, with reanalyses (ECMWF ERA5) andsatellite observations for clouds (MSG), precipitation (TRMM B42) and surface wind (ASCAT). The sea breeze/ land breeze alternation and its connection with the low-level wind divergence and surface temperature gradientwere found to strongly dominate the diurnal signal. Reanalyses and observations were then compared to betterunderstand the poor representation of precipitation in the mod