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Étude de la polycystine-1 délété de son motif coiled-coil sur les mécanismes intracellulaires in vivoPaul, Marie-Lorna 04 1900 (has links)
La polykystose rénale autosomique dominante (PKRAD) est une maladie génétique rénale qui se manifeste par le développement de kystes au rein. Elle résulte de mutations dans le gène PKD1/polycystine-1 (PC-1), contenant un motif coiled-coil et dans le gène PKD2/PC-2 dont les fonctions restent à élucider. À partir d’un chromosome artificiel bactérien, le gène Pkd1 murin (BAC-Pkd1) a été modifié afin de générer 4 lignées de souris transgéniques délété du motif coiled-coil Pkd1Δcoiled-coil et 3 lignées contrôles Pkd1TAG possédant 1-35 copies du transgène. Ces 2 transgènes ont un profil d’expression identique à l’endogène et le niveau dépend du nombre de copies. Alors que les souris Pkd1TAG développent la PKRAD de sévérité proportionnelle au niveau d’expression, les lignées Pkd1Δcoiled-coil en sont épargnées. Ces résultats démontrent l’importance du motif coiled-coil dans la maladie. Les souris Pkd1Δcoiled-coil croisées par Pkd1-/- (létale à la naissance), Pkd1-/- ; Pkd1Δcoiled-coil survivent après la naissance et permettent d’analyser in vivo les interactions, la signalisation et le rôle physiologique du motif coiled-coil. Ces souris Pkd1-/- ; Pkd1Δcoiled-coil avec une copie du transgène présentent des kystes rénaux et meurent ~2 semaines alors que celles à hautes copies n’ont aucun phénotype comme les Pkd1TAG. Les résultats génétiques et biochimiques démontrent que Pc-1Δcoiled-coil est hypomorphe. Bien que Pc-1Δcoiled-coil subit son clivage autoprotéolytique, l’analyse du transport intracellulaire de Pc1Δcoiled-coil montre un délai de maturation. Alors qu’in vitro le trafic Pc-1/Pc-2 dépend du motif coiled-coil pour leur interaction, in vivo une interaction Pc-1Δcoiled-coil/Pc-2 est détectée, suggérant un site d’interaction distinct. Nos études in vivo démontrent que le motif coiled-coil de Pc-1 joue un rôle clé dans sa maturation et l’existence d’un nouveau partenaire de Pc-1 pour son transport intracellulaire. / Autosomal dominant polycystic kidney disease (ADPKD) is the most prevalent genetic disorder that is characterize by the formation of bilateral renal cysts and leads to kidney failure. It results from mutations in the PKD1/polycystin-1(PC-1) gene, containing a coiled-coil motif, and in the PKD2/PC-2 gene, the functions of which remain to be elucidated. From a bacterial artificial chromosome, the murine Pkd1 gene (Pkd1-BAC) was modified in order to obtain 4 transgenic mouse lines deleted from it coiled-coil motif (Pkd1Δcoiled-coil) and 3 Pkd1TAG control lines possessing 1-35 copies of the transgene. These two transgenes have an expression profile identical to the endogenous gene and their expression depends on the number of copies. While Pkd1TAG mice develop ADPKD with a severity proportional to the level of expression, the Pkd1Δcoiled-coil lines are spared. These results demonstrate the importance of the coiled-coil motif in the disease. Pkd1Δcoiled-coil mice crossed by Pkd1-/- (lethal by birth), Pkd1-/-; Pkd1Δcoiled-coil survive after birth and allow the interactions, signaling and physiological role of the coiled-coil motif to be analyzed in vivo. These Pkd1-/-; Pkd1Δcoiled-coil mice with one copy of the transgene show kidney cysts and die ~ 2-weeks while high-copy ones have no phenotype as opposed to Pkd1-/-; Pkd1TAG who eventually develop cyst after 1 year. The genetic and biochemical results demonstrate that Pc-1Δcoiled-coil is hypomorphic. Although Pc-1Δcoiled-coil undergoes its autoproteolytic cleavage, analysis of the intracellular transport of Pc-1Δcoiled-coil shows a delay in maturation. While Pc-1 and Pc-2 appear to interact in vitro through their coiled-coil motif and co-transport, a Pc-1Δcoiled-coil -Pc-2 interaction is conserved in the kidney, suggesting a distinct mechanism of interactions in vivo. Thus, our results show that the coiled-coil motif of Pc-1 in vivo is involved in the maturation independently of Pc-2, highlighting the existence of a critical partner in intracellular transport.
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Polycystin-2 (PKD2), Eccentric (XNTA), and Meckelin (MKS3) in the Ciliated Model Organism Paramecium tetraureliaValentine, Megan Smith 01 January 2015 (has links)
Paramecium tetraurelia is a ciliated single cell used as a model organism for the study of ciliopathies. Ciliopathies are mammalian diseases involving the dysfunction of cilia, including cilia maintenance, construction, and signaling. P. tetraurelia and its cilia provides an excellent non-canonical system for the investigation and elucidation of proteins important for the structure, maintenance and function of cilia and ciliary beating. We utilize features of this cell such as its 1000's of cilia and highly organized and patterned cell surface to observe changes in swimming behavior or disruptions in the ordered cell surface which are not feasible in mammalian cells. Here, we present research on three proteins in Paramecium, two of which are homologs to human ciliopathy genes. Using combinations of epitope-tagging, RNA interference (RNAi), immunofluorescence, immunoprecipitations, LC-MS/MS analysis and electrophysiology, we have attempted to elucidate the location, function, and potential interacting partners of these three proteins.
The first protein, meckelin (MKS3), is a contributing factor in Meckel-Gruber syndrome, among other ciliopathies. Using epitope tagging, we identified the location of the Mks3 protein above each basal body. Depletion of MKS3 using RNAi leads to global loss of cilia, a severe disruption in the surface organization and a mislocalization of basal bodies out of the anterior-posterior axis of the cell. We show that depletion of Mks3 leads to abnormal backward swimming in ionic stimuli and depleted secretion of trichocysts. Based on our data, we propose two functions for Mks3 in P. tetraurelia. The first function is a transition zone component important for proper regulation of ciliary protein content, consistent with MKS3 function in other organisms. The depletion of MKS3 led to global ciliary loss, but also an imbalance in the ciliary ion channels that was different from the loss of cilia due to interference with intraflagellar transport as observed in cells depleted of IFT88. The second novel role for MKS3 is as a transient connection to the kinetodesmal fiber which is important for basal body guidance when daughter basal bodies migrate away from the mother basal body before cell division.
We also examine the contribution of the non-selective cation channel Polycystin-2 (Pkd2) in Paramecium to Mg2+ permeability and Mg2+-induced behavior. When mutated in humans, Pkd2 leads to 15% of the cases of Autosomal Dominant Polycystic Kidney Disease (ADPKD). When PKD2 is depleted using RNAi in Paramecium, cells show short backward swimming in Mg2+ solutions, a resistance to heavy metal paralysis, and depleted membrane permeability to Mg2+. The channel-like protein XntA which is unique to Paramecium and Tetrahymena, is also important for these phenotypes. Therefore, we utilized the Paramecium XntA1 mutant in our studies, which lacks Mg2+-induced behavior. We demonstrate that both Pkd2 and XntA are present in the cell membrane and in the cilia. Co-IP assays show that the IP of XntA-myc co-IPs the Pkd2-FLAG channel, but not vice versa, possibly because of an occluded FLAG epitope due to protein interactions. To tease apart the contributions of Pkd2 in the cilia and the cell membrane, electrophysiology was used to measure membrane potential of ciliated and deciliated cells. Depletion of BBS8 eliminates Pkd2 in the cilia, allowing us to examine Pkd2 activity restricted to the cell membrane of ciliated cells. Depletion of Pkd2 or XntA decreases membrane permeability to Mg2+. When Pkd2 was restricted to the cell membrane via BBS8 depletion, the membrane permeability to Mg2+ increased, much like over-expressing the Pkd2 protein. Depletion of Pkd2, especially in the deciliated XntA1 mutant, leads to a dramatic decrease in Mg2+ membrane permeability. Based on these data, we propose that Pkd2 is the Mg2+ channel in Paramecium and XntA is not a channel, but is perhaps important for stabilizing Pkd2 in membrane microdomains.
We have uncovered novel function roles for the proteins mentioned here, leading to a broader understanding of their function. These studies also highlight to usefulness and importance of the model organism Paramecium tetraurelia to the study of human ciliopathy genes.
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Polycystin-1 and Bone MechanotransductionHuang, Wei January 2012 (has links)
Bone mechanotransduction is a fundamental process underlying the remarkable ability of bones to perceive surrounding physical cues and adapt their mass, structure and overall strength to their mechanical environment. Therefore, it is central to many aspects of bone biology and disease. The key to a mechanistic understanding of this process lies in better knowledge of critical signaling molecules that relay the mechanical information inside bone cells. In this thesis, we investigate the role of polycystin-1 (PC1), a proposed fluid flow sensor in kidney epithelial cells, in transducing mechanical signals in bone cells. Loss of PC1 in osteoblast lineage cells using osterix-Cre (Osx-Cre) causes mild osteopenia in mice with reduced calvarial and trabecular bone formation, and markedly attenuated anabolic bone formation responses to in vivo mechanical loading of long bones. Loss of PC1 in limb bud mesenchymal cells at an early stage causes mildly increased bone formation and a tendency to exhibit enhanced anabolic responses to in vivo mechanical loading of long bones. These findings suggest that PC1 has a complex role in different bone cell populations both during development and in bone mechanotransduction. PC1 has been shown to mediate tensile force-induced proliferation in osteoprogenitor cells (OPCs) in craniofacial sutures. To investigate the role of PC1 in periosteal osteoprogenitor mechanotransduction, we establish a shockwave-induced periosteum mechanical stress model. Shockwave treatment triggers dramatically increased cell proliferation, potent osteogenic activity, and intramembranous new bone formation in the periosteum. We show that loss of PC1 in periosteal cells (Prx1-Cre) does not affect periosteal mechanoresponsiveness to shockwave mechanical stress. These findings suggest that the role of PC1 in OPCs is likely tissue or force dependent. Fluid shear stress (FSS) in the lacunar-canalicular network is a major force element that osteocytes experience and respond to in vivo. To study the role of PC1 in FSS-mediated osteocyte/osteoblast mechanotransduction, we establish a laminar FSS system with custom-made flow chambers and a PC1-deficient osteoblast cell line. Our data show that PC1 is essential for regulation of FSS-induced initial \(Ca^{2+}\) influx in osteoblasts and mediates osteoblast FSS responses in a COX-2 and AP-1 independent manner.
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In vitro studies of protein interactions on substrate supported artificial membranesMorick, Daniela 23 January 2013 (has links)
Da eine Vielzahl von Proteininteraktionen innerhalb zellulärer Organismen an der Grenzfläche zu Membranen stattfindet, ist die Untersuchung dieser Prozesse von gro-ßem wissenschaftlichem Interesse. Ziel dieser Arbeit war es Modellsysteme basierend auf artifiziellen Membranen zu entwickeln, mit deren Hilfe die Untersuchung ausge-wählter Proteininteraktionen ermöglicht werden konnte.
Im ersten Abschnitt dieser Arbeit (Kapitel 4-6) wurde ein Biosensorassay basierend auf festköperunterstützten Membranen entwickelt, der die Quantifizierung der Interaktion von C-Polycystin-2 (cPC2) mit seinen Interaktionspartnern C-Polycystin-1 (cPC1) und PIGEA14 mittels der Quarzmikrowaagetechnik ermöglichte. Aufgrund der Tatsache, dass die Affinität von cPC2 zu cPC1 in Anwesenheit von Ca2+ dreifach höher war, wurde eine Ca2+ abhängige Trimerisierung von cPC2 postuliert. Die Unterschiede der ermittelten kinetischen Koeffizienten führten zur Entwicklung eines Bindunsgmodells, welches die dreistufige Adsorption von cPC2 an cPC1 in Abwesenheit bzw. einstufige Adsorption in Anwesenheit von Ca2+ implizierte. Im Falle der Interaktion von cPC2 mit PIGEA14 wurde die Abhänigkeit der cPC2 Bindung von der Pseudophosphorylie-rung des Proteins an Ser812 untersucht. Es wurde festgestellt, dass die Affinität der pseudophosphorylierten Mutante cPC2S812D zu PIGEA14 zweifach niedriger war, als die von cPC2wt.
Im zweiten Abschnitt der Arbeit (Kapitel 7 und 8) wurde die spezifische Wechselwir-kung von filamentösem Aktin (F-Aktin) mit festkörperunterstützten und porenüber-spannenden Membranen untersucht. Die kontrollierte Anbindung von F-Aktin in und auf porösen Aluminiumoxidfilmen konnte mit Hilfe verschiedener Funktionalisie-rungsstrategien erzielt werden. Der Einfluss eines F-Aktin Netzwerks auf die Span-nung und viskoelastischen Eigenschaften porenüberspannender Membranen wurde mittels kraftmikroskopischer Studien untersucht. Es wurde nachgewiesen, dass der Einfluss von gebundenem F-Aktin auf die Membranspannung gering war, aber erst durch die F-Aktin Adhäsion viskoelastische Membraneigenschaften induziert wurden.
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Mechanism of Calcium Spikes during CytokinesisPoddar, Abhishek January 2022 (has links)
No description available.
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Regulation of STAT6, STAT3 and STAT1 by the Cytoplasmic Tail of Polycystin-1, the Protein Affected in Polycystic Kidney DiseaseShivakumar, Vasanth 01 May 2007 (has links)
No description available.
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Membrane Proteins Take Different Trafficking Pathways to the Primary CiliumMonis, William Joseph 14 December 2017 (has links)
Cilia are conserved organelles that extend from the surface of most eukaryotic cells. During development cilia play key roles in force generation and perception of the extracellular environment. Ciliary defects cause a broad class of human diseases called ciliopathies characterized by pleiotropic symptoms including cystic kidneys, retinal degeneration, cardiac malformations and skeletal deformations. Perception of the environment relies on specific proteins being localized to the ciliary membrane compartment. The mechanism for sorting and trafficking membrane proteins to the cilium is poorly understood. To address this question, I developed a fluorescence-based pulse-chase assay to measure the transport kinetics of ciliary membrane proteins. This assay was used to determine the importance of candidate proteins to the delivery of fibrocystin, polycystin-2, and smoothened to cilia. Using this assay, I found that ciliary delivery of fibrocystin and polycystin-2 requires IFT20, GMAP210 and the exocyst while smoothened delivery is largely independent of these proteins. In addition, I determined that polycystin-2, but not smoothened or fibrocystin require the biogenesis of lysosome related organelles complex-1 (BLOC-1) for ciliary delivery. Consistent with a requirement for BLOC-1 in ciliary transport of polycystin-2, BLOC-1 mutant mice have cystic kidney disease. BLOC-1 functions in endosomal sorting and I find that disrupting the recycling endosome also reduced ciliary polycystin-2 and causes its accumulation in the recycling endosome. This is the first demonstration of a role for BLOC-1 in ciliary biogenesis and highlights the complexity of trafficking pathways to the cilium.
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Des Polycystines au centrosome, une enzyme clef : la calcium/calmoduline dependent kinase 2 / From polycystins to centrosomes, a key enzyme : the calcium/calmodulin dependant kinase 2Ribe-Pinachyan, Emilie 16 December 2010 (has links)
La polykystose rénale autosomique dominante (ADPKD) est la maladie monogéniquehumaine la plus fréquente (prévalence 1/800). Les gènes responsables de cette maladie sont PKD1(codant pour PC1) ou PKD2 (codant pour PC2). La maladie évolue vers l’insuffisance rénale terminale.Aujourd’hui, seul un traitement symptomatique est proposé aux malades. Les mécanismes à l’originede l’ADPKD sont mal connus. Les modèles animaux permettent de mieux comprendre laphysiopathologie d’une maladie. Il n’existe pas de bon modèle de polykystose (même causemoléculaire, même mode de transmission, même signes cliniques). En utilisant la transgénose degrands fragments, nous avons créé un modèle de surexpression de PKD2 humain. Le transgène estsous le contrôle de son promoteur naturel humain. Cette souris exprime deux fois plus de PC2 queles sauvages. Elle ne présente que quelques microkystes mais une tubulopathie associant défaut deconcentration des urines et protéinurie tubulaire. La surexpression de PC2 inhibe l’expression degènes codant pour des protéines de la matrice extracellulaire. Le phénotype cellulaire de cesanimaux est remarquable : un tiers des cellules présentent un nombre élevé de centrosomes. Cephénotype cellulaire a été retrouvé chez des souris sous exprimant Pkd2 et chez des souris sousexprimant Pkd1. Ce caractère multicentrosomique est corrigé en incubant les cellules avec uninhibiteur de CaMKII ou en croisant nos souris transgéniques avec une souris KO de Camk2. Nousavons réussi à lier CaMKII, la duplication des centrosomes et les polycystines, in vitro et in vivo. Ceciamène un éclairage nouveau sur la duplication du centrosome et la physiopathologie de l’ADPKD. / Autosomal Dominant Polycystic Kidney Disease (ADPKD) is the most common monogenic human disease (prevalence 1/800). Genes responsible for this disease are PKD1 (encoding PC1) or PKD2 (encoding PC2). The disease progresses to end stage renal disease. Today, only symptomatic treatment is offered to patients. The mechanisms underlying the ADPKD are unknown. Animals models allow better understand the disease’s pathophysiology. There is no good model of ADPKD (same molecular cause, same clinical signs). We created a mice model of human PKD2 overexpression. The transgène is under the control of its human natural promoter. This mouse expresses PC2 twice as much as the wild. It shows only few microcysts but tubulopathy involving lack of urine concentration and tubular proteinuria. PC2 overexpression inhibits the expression of genes encoding proteins of the extracellular matrix. The cellular phenotype of these animals is special : one third of the cells have a high number of centrosomes. This cellular phenotype was found in Pkd2 Knockout mice and in Pkd1 knockout mice. This multicentrosomic character is corrected by incubating the cells with a CaMKII inhibitor or by crossing our transgenic mice with Camk2 knockout mice. We propose a link between CaMKII, Centrosome duplication and polycystin in vitro and in vivo. This brings a new light on centrosome duplication and pathophysiology of ADPKD.
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Characterization of polycystin-1 in ADPKD pathogenetic mechanism : biogenesis and functional implications by genetic approaches in mouseKurbegovic, Almira 03 1900 (has links)
La polykystose rénale autosomique dominante (ADPKD) est une des maladies génétiques les plus communes. ADPKD se manifeste le plus souvent au stade adulte par la présence de kystes rénaux, et bien souvent de kystes hépatiques, avec une progression très variable. ADPKD mène à une insuffisance rénale: les seuls recours sont la dialyse puis la transplantation rénale. Les mutations dispersées sur les gènes PKD1 (majoritairement; la protéine polycystine-1, PC1) et PKD2 (la protéine polycystine-2, PC2) sont responsables de l’ADPKD. Le mécanisme pathogénétique de perte de fonction (LOF) et donc d’un effet récessif cellulaire est évoqué comme causatif de l’ADPKD. LOF est en effet supporté par les modèles murins d’inactivation de gènes PKD1/PKD2, qui développent de kystes, quoique in utéro et avec une rapidité impressionnante dans les reins mais pas dans le foie. Malgré de nombreuses études in vitro, le rôle de PC1/PC2 membranaire/ciliaire reste plutôt hypothétique et contexte-dépendant. Ces études ont associé PC1/PC2 à une panoplie de voies de signalisation et ont souligné une complexité structurelle et fonctionnelle exceptionnelle, dont l’implication a été testée notamment chez les modèles de LOF. Toutefois, les observations patho-cellulaires chez l’humain dont une expression soutenue, voire augmentée, de PKD1/PC1 et l’absence de phénotypes extrarénaux particuliers remet en question l’exclusivité du mécanisme de LOF. Il était donc primordial 1) d’éclaircir le mécanisme pathogénétique, 2) de générer des outils in vivo authentiques d’ADPKD en terme d’initiation et de progression de la maladie et 3) de mieux connaitre les fonctions des PC1/PC2 indispensables pour une translation clinique adéquate. Cette thèse aborde tous ces points. Tout d’abord, nous avons démontré qu’une augmentation de PKD1 endogène sauvage, tout comme chez l’humain, est pathogénétique en générant et caractérisant en détail un modèle murin transgénique de Pkd1 (Pkd1TAG). Ce modèle reproduit non seulement les caractéristiques humaines rénales, associées aux défauts du cil primaire, mais aussi extrarénales comme les kystes hépatiques. La sévérité du phénotype corrèle avec le niveau d’expression de Pkd1 ce qui supporte fortement un modèle de dosage. Dans un deuxième temps, nous avons démontré par les études de complémentations génétiques que ces deux organes reposent sur une balance du clivage GPS de Pc1, une modification post-traductionelle typique des aGPCR, et dont l’activité et l’abondance semblent strictement contrôlées. De plus, nous avons caractérisé extensivement la biogénèse de Pc1 et de ses dérivés in vivo générés suite au clivage GPS. Nous avons identifié une toute nouvelle forme et prédominante à la membrane, la forme Pc1deN, en plus de confirmer deux fragments N- et C-terminal de Pc1 (NTF et CTF, respectivement) qui eux s’associent de manière non-covalente. Nous avons démontré de façon importante que le trafic de Pc1deN i.e., une forme NTF détachée du CTF, est toutefois dépendant de l’intégrité du fragment CTF in vivo. Par la suite, nous avons généré un premier modèle humanisant une mutation PKD1 non-sens tronquée au niveau du domaine NTF(E3043X) en la reproduisant chez une souris transgénique (Pkd1extra). Structurellement, cette mutation, qui mimique la forme Pc1deN, s’est également avérée causative de PKD. Le modèle Pkd1extra a permis entre autre de postuler l’existence d’une cross-interaction entre différentes formes de Pc1. De plus, nos deux modèles murins sont tous les deux associés à des niveaux altérés de c-Myc et Pc2, et soutiennent une implication réelle de ces derniers dans l’ADPKD tou comme une interaction fonctionnelle entre les polycystines. Finalement, nous avons démontré un chevauchement significatif entre l’ADPKD et le dommage rénal aigüe (ischémie/AKI) dont une expression augmentée de Pc1 et Pc2 mais aussi une stimulation de plusieurs facteurs cystogéniques tel que la tubérine, la β-caténine et l’oncogène c-Myc. Nos études ont donc apporté des évidences cruciales sur la contribution du gène dosage dans l’ADPKD. Nous avons développé deux modèles murins qui serviront d’outil pour l’analyse de la pathologie humaine ainsi que pour la validation préclinique ADPKD. L’identification d’une nouvelle forme de Pc1 ajoute un niveau de complexité supplémentaire expliquant en partie une capacité de régulation de plusieurs voies de signalisation par Pc1. Nos résultats nous amènent à proposer de nouvelles approches thérapeutiques: d’une part, le ciblage de CTF i.e., de style chaperonne, et d’autre part le ciblage de modulateurs intracellulaires (c-Myc, Pc2, Hif1α). Ensemble, nos travaux sont d’une importance primordiale du point de vue informatif et pratique pour un avancement vers une thérapie contre l’ADPKD. Le partage de voies communes entre AKI et ADPKD ouvre la voie aux approches thérapeutiques parallèles pour un traitement assurément beaucoup plus rapide. / Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common genetic diseases. ADPKD is manifested by the presence of renal cysts detected most often in the adult stage, and frequently liver cysts, with highly variable progression. ADPKD leads to kidney failure with the only recourse of dialysis and eventual kidney transplantation. Mutations dispersed throughout the PKD1 gene (major player, the polycystin-1 protein, PC1) and the PKD2 gene (polycystin-2 protein, PC2) are responsible for ADPKD. The loss of function (LOF) pathogenetic mechanism, and therefore a cellular recessive effect, has been suggested as causative of ADPKD. LOF is indeed supported by the PKD1/PKD2 gene inactivation mouse models, which develop cysts, although in utero with impressive speed in the kidney but not in the liver. Despite many in vitro studies, the membrane/ciliary role of PC1/PC2 remains rather hypothetical and context-dependent. These studies have associated PC1/PC2 to a variety of signaling pathways and underlined exceptional structural and functional complexity, whose involvement has been tested especially in LOF models. However, pathocellular observations in humans with sustained and even increased expression of PKD1/PC1, and the absence of particular human extrarenal phenotypes questions the exclusivity of the LOF mechanism. It was therefore essential 1) to clarify the pathogenetic mechanism, 2) to generate in vivo tools authentic of ADPKD in terms of initiation and progression of the disease and 3) to better understand the essential functions of PC1/PC2 for an adequate clinical translation. This thesis addresses all of these issues. First, we demonstrated that an increase in endogenous PKD1, just like in humans, is pathogenetic by generating and characterizing in detail a transgenic mouse model of Pkd1 (Pkd1TAG). This model not only reproduces the renal human characteristics associated with defects of the primary cilium, but also the extrarenal, namely, liver cysts. The severity of the phenotype correlates with the expression level of Pkd1, which strongly supports a dosage model. Secondly, we have demonstrated with genetic complementation studies that these two organs rely on a balance of Pc1 GPS cleavage, a typical post-translational modification of aGPCR, whose activity and abundance seem strictly controlled. Furthermore, we have extensively characterized Pc1 biogenesis and its derivatives in vivo generated upon GPS cleavage. We have identified a new form, predominantly on the membrane, the Pc1deN form, in addition to confirming the two N- and C-terminal Pc1 fragments (NTF and CTF, respectively), which associate non-covalently. Importantly, we have demonstrated that traffic of Pc1deN i.e., the NTF form detached from the CTF, is still dependant on the integrity of the CTF fragment. Next, we generated a first model humanizing a PKD1 nonsense truncated mutation at the level of the NTF(E3043X) domain by reproducing it in a transgenic mouse (Pkd1extra). Structurally, this mutation, which mimics Pc1deN, has also been shown to be causative of PKD. The Pkd1extra model allowed the proposition of the existence of a cross-interaction between different forms of Pc1. In addition, our two mouse models are both associated with altered levels of c-Myc and Pc2, which is supportive of their involvement in ADPKD and a functional interaction between the polycystins. Finally, we have shown a significant overlap between ADPKD and acute renal injury (ischemia/AKI) namely increased expression of Pc1 and Pc2 but also stimulation of several cystogenic factors such as tuberin, β-catenin and the oncogene c-Myc. Our studies have therefore given crucial evidence to the contribution of PKD1 gene dosage mechanism in ADPKD. We have developed two mouse models, which can serve as a tool for the analysis of human pathology as well as for preclinical validation of ADPKD. The identification of a new form of Pc1 adds an additional level of complexity in part explaining the regulation capacity of Pc1 on several signaling pathways. Our findings lead us to propose new therapeutic approaches: firstly, targeting the CTF i.e., chaperone style, and also targeting intracellular modulators (c-Myc, Pc2, Hif1α). Together, our work is of paramount importance in an informative point of view and practical perspective for progress towards a therapy for treating ADPKD. The sharing of common pathways between AKI and ADPKD paves the way for parallel therapeutic approaches for assured much faster treatment.
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