Epigenetic control of gene expression by histone post-translational modifications (PTMs) is a complex process regulated by proteins that can 'read', 'write' or 'erase' these PTMs. The histone lysine demethylase (KDM) family of epigenetic enzymes remove methyl modifications from lysines on histone tails. The Jumonji C domain (JmjC) family is the largest family of KDMs. Investigating the scope and mechanisms of the JmjC KDMs is of interest for understanding the diverse functions of the JmjC KDMs in vivo, as well as for the application of the basic science to medicinal chemistry design. The work described in this thesis aimed to biochemically investigate the inhibitor and substrate diversity of the JmjC KDMs, it led to the identification of new inhibitors and substrates and revealed a potential combinatorial dependence between adjacent histone PTMs. Structure-activity relationship studies gave rise to an n-octyl ester form of IOX1 with improved cellular potency and selectivity towards the KDM4 subfamily. This compound should find utility as a basis for the development of JmjC inhibitors and as a tool compound for biological studies. The rest of this thesis focused on the biochemical investigations of potential substrates and inhibitors for KDM3A, a JmjC demethylase with varied physiological functions. Kinetic characterisation of reported KDM3A substrates was used as the basis for evaluations of novel substrates and inhibitors. Further studies found TCA cycle intermediates to be moderate co-substrate competitive inhibitors of KDM3A. Biochemical investigations were carried out to study potential protein-protein interactions of KDM3A with intraflagellar transport proteins (IFTs), non-histone proteins involved in the formation of sperm flagellum. Work then addressed the exploration of novel in vitro substrates for KDM3 (KDM3A and JMJD1C) mediated catalysis, including: methylated arginines, lysine analogues, acetylated and formylated lysines. KDM3A, and other JmjC KDMs, were found to catalyse novel arginine demethylation reaction in vitro. Knowledge gained from studies with unnatural lysine analogues was utilised to search for additional novel PTM substrates for KDM3A. These results constitute the first evidence of JmjC KDM catalysed hydroxylation of an Nε-acetyllysine residue. The H3 K4me3 position seems to be required for acetyllysine substrate recognition, implying a combinatorial effect between PTMs. Preliminary results provide evidence that JMJD1C, a KDM3 protein previously reported to be inactive, may catalyse deacetylation in vitro. An additional novel reaction, observed with both KDM3A and JMJD1C, is deformylation of N^ε-formyllysine residues on histone H3 fragment peptides. Interestingly, H3 K4 methylation was also observed to enhance the apparent deformylation of both KDM3A and JMJD1C catalysed reactions. Overall, findings in this thesis suggest that the catalytic activity of JmjC KDMs extends beyond lysine demethylation. In a cellular context, members of the KDM3 subfamily might provide a regulatory link between methylation and acylation marks. Such a link will further highlight the complex relationships between histone PTMs and the epigenetic enzymes that regulate them. The observed dependency of H3 K9 catalysis on H3 K4 methylation adds another layer of complexity to the epigenetic regulation by histone PTMs.

Proteins and RNAs are two of the most versatile macromolecules that carry out almost all functions within living organisms. In this thesis I have explored evolutionary and regulatory aspects of proteins and RNAs by studying their structures, modifications and interactions. In the first chapter of my thesis I investigate domain atrophy, a term I coined to describe large-scale deletions of core structural elements within protein domains. By looking into truncated domain boundaries across several domain families using Pfam, I was able to identify rare cases of domains that showed atrophy. Given that even point mutations can be deleterious, it is surprising that proteins can tolerate such large-scale deletions. Some of the structures of atrophied domains show novel protein-protein interaction interfaces that appear to compensate and stabilise their folds. Protein-protein interactions are largely influenced by the surface and charge complementarity, while RNA-RNA interactions are governed by base-pair complementarity; both interaction types are inherently different and these differences might be observed in their interaction networks. Based on this hypothesis I have explored the protein-protein, RNA-protein and the RNA-RNA interaction networks of yeast in the second chapter. By analysing the three networks I found no major differences in their network properties, which indicates an underlying uniformity in their interactomes despite their individual differences. In the third chapter I focus on RNA-protein interactions by investigating post-translational modifications (PTMs) in RNA-binding proteins (RBPs). By comparing occurrences of PTMs, I observe that RBPs significantly undergo more PTMs than non-RBPs. I also found that within RBPs, PTMs are more frequently targeted at regions that directly interact with RNA compared to regions that do not. Moreover disorderedness and amino acid composition were not observed to significantly influence the differential PTMs observed between RBPs and nonRBPs. The results point to a direct regulatory role of PTMs in RNA-protein interactions of RBPs. In the last chapter, I explore regulatory RNA-RNA interactions. Using differential expression data of mRNAs and lncRNAs from mouse models of hereditary hemochromatosis, I investigated competing regulatory interactions between mRNA, lncRNA and miRNA. A mutual interaction network was created from the predicted miRNA interaction sites on mRNAs and lncRNAs to identify regulatory RNAs in the disease. I also observed interesting relations between the sense-antisense mRNA-lncRNA pairs that indicate mutual regulation of expression levels through a yet unknown mechanism.

Bcl-xL est un oncogène surexprimé dans plusieurs types de cancers et qui joue un rôle important dans la survie cellulaire en régulant deux processus: l'apoptose et l'autophagie. Récemment, nous avons identifié l'existence d'une nouvelle forme de Bcl-xL qui subit une simple déamidation sur le résidu Asn52. Cette forme monodéamidée est exprimée en conditions contrôles et apparaît spontanément in vitro et in vivo. La déamidation de Bcl-xL produit un mélange de protéines contenant en position 52 soit un résidu Asp, soit un résidu isoAsp. L'objectif de cette thèse est de caractériser les fonctions de ces deux espèces protéiques, et de déterminer comment la monodéamidation de Bcl-xL modifie les fonctions de survie de cet oncogène. Nous avons montré que le mutant déamido-mimétique Bcl-xL N52DN66A conserve la même fonction anti-apoptotique que Bcl-xL native, mais présente une activité autophagique plus grande, et des propriétés oncogéniques et tumorigéniques altérées in vitro, ex vivo et in vivo. Nous avons étudié certains des mécanismes impliqués dans la régulation de l'autophagie et les propriétés oncogéniques comme la voie mTor, les voies de signalisation médiées par l'oncogène Ras, ainsi que l'activité métabolique et l'état souche des cellules. D'autre part, nous avons aussi développé des tests in vitro pour analyser les interactions établies par les formes déamidées de Bcl-xL comportant un isoAsp. L'ensemble de nos données permet de suggérer une régulation des fonctions de Bcl-xL par des mécanismes indépendants de l'apoptose, et renforce l'importance d'explorer les fonctions non apoptotiques de cette protéine pour mettre en évidence sa capacité à promouvoir la survie cellulaire et entraîner la progression du cancer. / Bcl-xL is an oncogene overexpressed in many types of cancer and which promotes cell survival by regulating two cellular processes : apoptosis and autophagy. We have recently identified a new form of this oncogene, which results from the deamidation of Asn52. This monodeamidated form is expressed under control conditions and is ubiquitously found in vitro and in vivo. Bcl-xL monodeamidation produces a mixture of proteins containing either an Asp residue or an IsoAsp residue in position 52. Our goal is to caracterise the functions of both species, and to determine how Bcl-xL monodeamidation modifies the survival functions of this oncogene. We have shown that the deamidomimetic mutant Bcl-xL N52DN66A retains the same anti-apoptotic function as the native protein, but exhibits enhanced autophagic activity and impaired clonogenic and tumorigenic properties in vitro, ex-vivo, and in vivo. We have studied certain of the mechanisms which can be involved in the regulation of autophagy and oncogenic properties of Bcl-xL such as mTor, Ras oncogene signaling pathway, metabolic activity measurement and stemness. We also implement in vitro assays to analyse the interactions established by isoAsp containing forms of Bcl-xL. Altogether our results support the view that deamidation regulates Bcl-xL oncogenic properties through apoptosis-independent mechanisms, and reinforce the importance of deciphering the non apoptotic functions of this protein to tackle its ability to sustain cell survival and drivecancer progression.

Abstract Rheumatoid arthritis (RA) is an autoimmune disease causing inflammation of synovial joints, which may lead to permanent changes in cartilage and bone tissues. RA patients have antibodies binding to citrullinated and also to carbamylated proteins. Antibodies binding to citrulline are associated with more severe disease progression and may already appear years before clinical disease onset. Citrulline and the lysine carbamylation product, homocitrulline, are similar in structure. Citrullinated proteins have been studied in RA and in neurological diseases, but researchers have been unaware of the effect of homocitrulline in citrulline detection methods. The purpose of the present study was to clarify the features of protein-bound citrulline and homocitrulline in relation to research done on citrullination and in immunological reactions related to rheumatoid arthritis. In the first study of this thesis the confounding role of homocitrulline in citrulline detection was shown. In the first and second study the features of experimentally induced antibodies were assessed. The antibodies induced with citrulline- and homocitrulline-containing protein structures were shown to react both with the ureido groups and the protein structures. The antibodies were able to distinguish between citrulline and homocitrulline in the same sequence even though binding to both. In the third study the simultaneous presence of citrulline and homocitrulline in RA synovial tissue was shown. In conclusion, considering the simultaneous presence of citrulline and homocitrulline and the binding features of the experimentally induced antibodies, homocitrulline could have a yet unsolved role in RA. Secondly, the existence of homocitrulline should be borne in mind in studies on citrullination. / Tiivistelmä Nivelreuma on niveltulehduksen aiheuttava autoimmuunitauti, joka voi johtaa pysyviin muutoksiin nivelen rusto- ja luukudoksessa. Nivelreumaa sairastavilla esiintyy vasta-aineita sitrullinoituneita ja karbamyloituneita proteiineja vastaan. Sitrulliiniin sitoutuvia vasta-aineita voi esiintyä elimistössä jo vuosia ennen taudin puhkeamista, ja niiden esiintyminen on yhdistetty vaikeampaan taudinkuvaan. Sitrulliini ja lysiinin karbamylaatiotuote homositrulliini ovat rakenteellisesti samankaltaisia. Proteiinien sitrullinaatiota on tutkittu nivelreumassa ja neurologisissa taudeissa, mutta homositrulliinin olemassaoloa tai sen vaikutusta tutkimusmenetelmiin ei ole huomioitu. Tämän tutkimuksen tarkoituksena oli selvittää proteiineihin sitoutuneiden sitrulliinin ja homositrulliinin ominaisuuksia aikaisempiin tutkimuksiin ja nivelreuman immunologisiin reaktioihin liittyen. Tässä tutkimuksessa homositrulliinin osoitettiin häiritsevän sitrulliinin tunnistamista. Ensimmäisessä ja toisessa osatyössä aiheutettiin kokeellisesti vasta-aineita sitrulliinia ja homositrulliinia sisältävillä proteiinirakenteilla. Vasta-aineiden havaittiin reagoivan sekä ureidoryhmän että proteiinirakenteen kanssa. Vasta-aineet pystyivät erottamaan sitrulliinin ja homositrulliinin toisistaan samassa rakenteessa, vaikka sitoutuivat kumpaankin. Kolmannessa osatyössä osoitettiin, että sitrulliinia ja homositrulliinia esiintyy samanaikaisesti nivelreumapotilaan tulehtuneessa nivelkalvossa. Tutkimus osoitti, että sitrulliinin ja homositrulliinin samanaikainen esiintyminen ja kokeellisesti aiheutettujen vasta-aineiden ominaisuudet huomioiden homositrulliinilla voi olla jokin toistaiseksi selvittämätön rooli nivelreumassa. Homositrulliinin olemassaolo on syytä huomioida sitrullinaatiota tutkittaessa.

Catharanthus roseus (Madagascar periwinkle) is the exclusive source of an array of terpenoid indole alkaloids (TIAs) that are used in the treatments of hypertension and certain types of cancer. TIA biosynthesis is under stringent spatiotemporal control and is induced by jasmonate (JA) and fungal elicitors. Tryptamine, derived from the indole branch, and secologanin from the iridoid branch are condensed to form the first TIA, strictosidine. Biosynthesis of TIA is regulated at the transcriptional level and several transcription factors (TFs) regulating the expression of genes encoding key enzymes in the pathway have been isolated and characterized. The JA-responsive APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF), ORCA3, and the basic helix-loop-helix (bHLH) factor, CrMYC2, are the key activators of the TIA biosynthesis. Recently, two other TFs, the bHLH IRIDOID SYNTHESIS 1 (BIS1) and BIS2 were also identified as regulators of TIA pathway. Analysis of C. roseus genome sequence has revealed that ORCA3 forms a physical cluster with two uncharacterized AP2/ERFs, ORCA4 and ORCA5. In plants, physically linked clusters of TFs are less characterized. Moreover, the regulation of TF clusters is relatively unexplored. My research uncovered that the ORCA gene cluster is differentially regulated. ORCA4 and ORCA5, while functionally overlapping with ORCA3, regulate an additional set of TIA pathway genes. ORCA4 or ORCA5 overexpression has resulted in significant increase of TIA accumulation in C. roseus hairy roots. In addition, ORCA5 directly regulates the expression of ORCA4 and indirectly regulates ORCA3, likely via unknown factor(s). Interestingly, ORCA5 also activates the expression of ZCT3, a negative regulator of the TIA pathway. In addition CrMYC2 is capable of activating ORCA3 and co-regulating pathway genes concomitantly with ORCA3. Several lines of evidence suggest that, in addition to the transcriptional control, biosynthesis of TIAs is also controlled at the posttranslational level, such as protein phosphorylation. Available literature indicates that a mitogen-activated protein kinase (MAPK) cascade is involved in this process. Analysis of C. roseus MAP kinome, identified two independent MAPK cascades regulating the indole and iridoid branches of the TIA pathway. We showed that the ORCA cluster and CrMYC2 act downstream of a MAP kinase cascade consisting of CrMAPKK1, CrMAPK3 and CrMAPK6. Overexpression of CrMAPKK1 in C. roseus hairy roots upregulates TIA pathway genes expressions and boosts TIA accumulation. The other cascade, consisting of CrMAPKK6 and CrMAPK13, mostly regulates the iridoid branch of the TIA pathway. Overexpression of CrMAPK13 in C. roseus hairy roots significantly upregulates iridoid pathway genes and boosts tabersonine accumulation. Moreover, we recently identified the third MAPK cascade, consisting of CrMAPKK1 and CrMAPK20, that negatively regulates the indole branch of the TIA pathway. Overexpression of CrMAPK20 in C. roseus hairy roots represses the genes regulated by CrMYC2-ORCAs and reduces catharanthine accumulation. These findings significantly advance our understanding of transcriptional and post-translational regulatory mechanisms that govern TIA biosynthesis in C. roseus.

La protéine Promyelocytic Leukemia (PML) est impliquée dans de nombreux processus cellulaires, et identifiée comme un suppresseur de tumeur. Cette protéine est le composant structural des Corps Nucléaires PML (CNs-PML) dont l'intégrité, compromise dans certaines leucémies, dépend strictement de sa SUMOylation. Ce projet de thèse visait à identifier de nouveaux régulateurs des CNs-PML, et par extension de la voie SUMO, en utilisant comme 'read-out' l'anatomie des CNs-PML, laquelle est extrêmement sensible au niveau de SUMOylation cellulaire globale. Ces travaux sont basés sur un criblage siARNs à grande échelle qui a conduit à l'identification de deux candidats SKP1et RBX1, tous deux faisant partie intégrante d'un complexe d'ubiquitine E3 ligase appelé " SKP1-CUL1-F-Box containing complex " (SCF). Nous avons pu démontrer l'implication de SKP1 et RBX1 dans la stabilité de la protéine PML avec des expériences de gain et perte de fonction. Nous avons également identifié FBXO9 comme la protéine F-Box capable de reconnaitre spécifiquement PML, causant son ubiquitination par le complexe SCFFBXO9, suivie de sa dégradation par le protéasome. En revanche, le site d'interaction de FBXO9 sur PML -tout comme la kinase impliquée dans ce processus de reconnaissance- restent encore à identifier. PML étant dégradé dans de nombreux cancers, il apparait essentiel d'avoir une meilleure compréhension des mécanismes post-traductionnels menant à sa dégradation. Ces travaux devraient à long terme permettre de révéler de nouveaux régulateurs des CNs-PML, et potentiellement permettre le développement de nouvelles stratégies thérapeutiques, visant à moduler les CNs-PML dans la cellule tumorale. / ProMyelocytic Leukemia (PML) protein is implicated in a number of key cellular processes, and was identified as a tumor suppressor. This protein is one of the main structural components forming the PML Nuclear Bodies (PML-NBs) whose integrity -compromised in some leukemias- is strictly dependent on PML SUMOylation. The goal of this thesis project was to identify new regulators of PML Nuclear Bodies, and by extension of the SUMO pathway, using PML-NBs, which are extremely sensitive to global cellular SUMOylation level, as a read out. This work is based on a high throughput siRNA screen, which led to the identification of two proteins, SKP1a and RBX1, which are both part of an Ubiquitin E3 ligase complex called SKP-Cullin-F-Box containing complex (SCF). We were able to show the involvement of SKP1 and RBX1 in PML protein stability through gain and loss of function experiments. We also identified FBXO9 as the F-Box capable of specifically recognizing PML, causing its ubiquitination by SCFFBXO9 complex and subsequent degradation by the proteasome. However, FBXO9 site of interaction on PML and the identity of the kinase implicated in this recognition processes are yet to be discovered. PML being degraded in numerous cancers, it is essential to acquire a better understanding of post-translational mechanism leading to the degradation of this tumour suppressor. In the long term, this work should, allow the discovery of new PML Nuclear Body regulators and potentially allow the development of new strategies aiming to modulate PML Nuclear Bodies in tumoral cells.

Phosphorylation mediated inactivation of PTEN leads to multiple malignancies with increased severity. However, the consequence of such inactivation on downstream functions of PTEN are poorly understood. Therefore, the objective of my thesis is to ascertain the molecular mechanisms by which PTEN phosphorylation drives lung cancer. PTEN phosphorylation at the C-terminal serine/threonine cluster abrogates its tumor suppressor function. Despite the critical role of the PTEN C-tail in regulating its function, the crystal structure of the C-tail remains unknown. Using bioinformatics and structural analysis, I determined that the PTEN C-tail is an intrinsically disordered region and is a hot spot for post-translational modifications (particularly phosphorylation) and protein-protein interactions. Evolutionary analysis of PTEN and its interacting proteins revealed that the PTEN C-tail has only recently evolved to acquire the ability to engage in a myriad of protein-protein interactions, resulting in its versatile functions. Replacement of the PTEN C-tail serine/threonine residues with alanines generated an artificial mutant, PTEN-4A, which remained “phospho-deficient” and therefore constitutively active. Interestingly, PTEN-4A suppressed cell proliferation and migration to a greater extent than PTEN-WT. PTEN-4A preferentially localized to the nucleus where it suppressed E2F-mediated transcription of cell cycle genes. PTEN physically interacted with the E2F1 protein and at E2F1-binding sites on chromatin, a likely mechanism for its transcriptional function. Further, deletion analysis on various PTEN domains revealed that the C2 domain of PTEN is indispensable for suppression of E2F-related genes. Systematic transcriptional promoter-reporter assays identified disease-associated C2 domain mutations that lose their ability to suppress E2F-mediated transcription, supporting the concept that these mutations are oncogenic in patients. Consistent with my findings, I observed increased level of PTEN phosphorylation and reduced nuclear PTEN levels in lung cancer patient samples. Further, to determine whether the enhanced growth-suppressive properties of PTEN-4A may be due to differential protein-protein interactions, I performed a comparative proteomic profiling of PTEN-WT and PTEN-4A interactomes using the SILAC methodology. Galectin-1 was identified as a candidate protein that binds preferentially to PTEN-WT and inhibits its tumor suppressive function. Taken together, the various tumor suppressive mechanisms of PTEN-4A may be harnessed therapeutically as adjunctive cancer therapy. Use of small molecule inhibitors that hinder PTEN C-tail phosphorylation is a plausible approach to activate PTEN function to reduce tumor burden.

Characterization of post-translational modifications (PTMs) of therapeutic proteins is very important during the bioprocess development to maintain desired product quality and during the submission process to regulatory authorities for product approval. Monitoring glycosylation in pharmacokinetic studies can be useful to evaluate the dependence of clearance rates on different glycoforms. The cost and efficiency of characterization affect the speed to market of biopharmaceutical proteins. A reduction in the number of manual processing steps, cost of reagents and consumption of sample, as well as the time required for chemical analysis, is therefore necessary. The research presented in this thesis is focused on the potential of using microfluidic discs for automated, miniaturized, parallel and rapid sample preparation for PTM characterization of therapeutic monoclonal antibodies. Paper I describes the method development for N-linked glycosylation profiling. Several sample preparation steps have been performed in an integrated process in the microfluidic compact disc (CD). Paper II demonstrates the use of the method presented in paper I in combination with multivariate statistics for discrimination of glycosylation profiles of different therapeutic antibodies and simulation of a real case of quality control. Paper III is focused on a method for monitoring changes in glycosylation profiles of therapeutic antibodies in serum over time by incubation with an exoglycosidase enzyme. Paper IV describes the method for peptide mapping of therapeutic antibodies. In addition, recent work (unpublished results) assesses the potential of this method for methionine oxidation detection. The developed methods were fast, robust with low sample/reagent consumption. Generation of glycosylation profile data for one sample was established in approximately 2 h. The amount of samples and antigens loaded into the CD platform for one replicate was less than 0.3 μg and approximately 0.06 μg, respectively. Furthermore, considering the parallel function of the CD, conducting the analysis for 54 samples can be completed within a day. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.</p>

No description available.

La conductivité hydraulique racinaire (Lpr) traduit la facilité du passage de l'eau au travers des racines. Ce paramètre, majoritairement contrôlé par l'activité de canaux hydriques membranaires (aquaporines), est modulable par diverses contraintes environnementales. Ce travail a permis de caractériser, sur un même organisme (Arabidopsis), les effets d'un ensemble de contraintes abiotiques et biotiques, représentatives de situations environnementales, sur la Lpr. Alors que la flagelline n'affecte pas la Lpr, les contraintes osmotiques (NaCl, mannitol), oxydantes (H2O2, NO) et nutritionnelles (carence en phosphate, en nitrate, culture des plantes en nuit prolongée) inhibent la Lpr. Par contre, la réalimentation en phosphate ainsi que l'addition de saccharose à des plantes cultivées en nuit prolongée stimulent la Lpr. Une approche phosphoprotéomique quantitative, basée sur l'analyse par MS de protéines microsomales racinaires purifiées à partir de plantes cultivées dans trois de ces contextes (NaCl, NO, phosphate) a permis de quantifier les variations d'abondance de l'ensemble des aquaporines racinaires ainsi que de leur état de MPT. D'un point de vue qualitatif, 22 aquaporines ont été identifiées dans la racine ainsi que plusieurs types de MPTs, incluant des nouveaux sites de phosphorylation (7), de méthylation (13 à 15), de formylation (4) et de déamidation (25 à 26). D'un point de vue quantitatif, cette étude a permis de conclure que les observations réalisées au niveau de la Lpr sont la résultante de mécanismes multifactoriels incluant l'état de phosphorylation des trois sites de l'extrémité C terminale de PIP2;1/2;2/2;3, l'état de phosphorylation de l'extrémité N terminale de PIP1;1/1;2, ainsi que les aquaporines TIPs. Ce travail permet donc de proposer de nouveaux mécanismes moléculaires impliqués dans la régulation de la Lpr en réponse à des contraintes de l'environnement / The water uptake capacity of plant roots (root hydraulic conductivity, Lpr) is mainly determined by water channels (aquaporins) and is modulated by environmental constraints. The present work characterised, in a unique organism (Arabidopsis), effects on Lpr of abiotic and biotic constraints representative of environmental situations. Whereas flagelline does not affect Lpr, osmotic (NaCl or mannitol), oxidative (H2O2 or NO) and nutritional (phosphate or nitrate starvation, prolonged night) stimuli inhibit Lpr. However, phosphate and sucrose resupply stimulate Lpr. A phosphoproteomics approach based on MS analysis of microsomal proteins extracted from roots of plants cultivated in different environmental constraints (NaCl, NO,phosphate starvation and resupply) allowed to quantify variations of abundance of roots aquaporins and of their PTMs. As a qualitative point of view, 22 aquaporins were identified in roots as well as several post-translational modifications including new sites of phosphorylation (7), methylation (13 to 15), formylation (4) and deamidation (25 to 26). From a quantitative point of view, the present work drove to the conclusion that the modulations of Lpr result from multifactorial mechanisms including the phosphorylation status of the C terminal part of PIP2;1/2;2/2;3 and of the N-terminal part of PIP1;1/1;2 and TIP aquaporins. This study proposes new molecular mechanisms implicated in Lpr regulation in response to various environmental situations.