Neuroblastoma is a childhood cancer of the peripheral sympathetic nervous system, emerging from cells of the neural crest. In Sweden, neuroblastoma accounts for 20 cases out of all, 300-350, pediatric cancer cases each year (Barncancerfonden 2019, Turup on behalf of Cancer Centrum 2019). This cancer often appears in the sympathetic ganglia and/or the adrenal gland and has a high rate of metastasis that often results in morbidity (Matthay et al. 2016). Recent findings implicating a mutation in the Rho/Rac signaling pathway, a pathway involved in neural crest differentiation and migration, were found in every fourth neuroblastoma patient (Dyberg et al. 2017) These mutations tend to shift Rho to a more active state which is believed to lead to more downstream Rho-associated Kinase (ROCK) activation. While inhibition of ROCK has been seen to promote MYCN protein degradation, induce neuroblastoma cell differentiation and repress neuroblastoma growth in vitro and in vivo (Dyberg et al. 2017). Rho/ROCK signaling pathway effects on cytoskeletal arrangement and cell shape have also been suggested to be involved in tumor promoted changes of the TME (Johan and Samuel, 2018). In this master’s thesis project, we explore the effects of the Rho/ROCK pathway on the tumor microenvironment (TME) and immune response (IR) in neuroblastoma. More specifically we are focusing on populations of T cells, macrophages and fibroblasts in tumors, and looking into tumor vascular structure (such as blood vessel) and extracellular matrix (ECM) formation after ROCK inhibitor treatment within neuroblastoma tumors from transgenic mice model TH-MYCN and multi-cellular tumor spheroids (MCTS), a three-dimensional (3D) in vitro model simulating TME in neuroblastoma cell lines. Through our studies we hope to find insights into the Rho/ROCK signaling pathway and involvement of the tumor microenvironment in cancer therapy, while elucidating potential new drugs and drug targets for improving outcomes in neuroblastoma treatment.

Cell polarity is required for asymmetric division, a mechanism to generate cell diversity by distributing fate determinants unequally to daughter cells. The establishment of polarity requires the evolutionarily conserved partitioning-defective (PAR) proteins as well as the actin cytoskeleton. In Caenorhabditis elegans one-cell embryos, the PAR proteins are segregated into an anterior (PAR-3, PAR-6) and a posterior (PAR-1, PAR-2) corticaldomain. The formation of PAR polarity correlates with anterior-posterior differences in the contractile activity of the cortex, known as "contractile polarity". It is thought that regulation of contractile polarity controls the establishment of PAR polarity, but detailed evidence to support this idea is lacking. To investigate how modulation of the actomyosin cytoskeleton affects polarity establishment, the acto-myosin cytoskeleton was perturbed by RNA-mediated interference (RNAi) of two Rho GTPases, CDC-42 and RHO-1. To examine how Rho GTPases are implemented in actin remodeling, it is important to analyze how their activity is controlled and how different activities affect polarity formation. The role of two putative Rho GTPase regulators, the Rho GTPase exchange factor (GEF) ECT-2 and the Rho GTPase activating protein (GAP) K09H11.3 were analyzed with respect to polarity formation. The formation of polarity was analyzed by using GFP-labeled proteins, and several different tracking methods were used to investigate the establishment of contractile and PAR polarity in more detail.This study demonstrates that both RHO-1 and CDC-42 are involved in polarity establishment in C. elegans embryos. But importantly, both act by different mechanisms. RHO-1 organizes the acto-myosin cytoskeleton into a contractile network, and therefore is essential for the formation of contractile polarity. The organization of the acto-myosin cytoskeleton is critical to ensure proper PAR protein distribution. Furthermore, a balance of RHO-1 activity by the GEF ECT-2 and the GAP K09H11.3 appears to be important for cortical contractility, for PAR protein domain size and for mutual exclusion of the PAR proteins. Although CDC-42 was shown to be a universal regulator of the actin cytoskeleton, CDC-42 acts downstream of contractile polarity. CDC-42 is required for linking PAR-6 to the cortex. In the absence of RHO-1 and ECT-2, PAR-6 and CDC-42 are not localized to the anterior cortex. This suggests that RHO-1, by organizing the actomyosin cytoskeleton into a contractile network, regulates the segregation of CDC-42 to the anterior cortex, and concomitantly PAR-6 localization. This study shows that the distribution of PAR is related to cortical activity and supports the model that the actin cytoskeleton plays an important role in polarity establishment.

LIMA, V.V. Papel da O-glicosilação com N-acetil-glucosamina (O-GlcNAc) nas alterações vasculares associadas a altos níveis de endotelina-1. 2012. 106 f. Tese (Doutorado) - Faculdade de Medicina de Ribeirão Preto Universidade de São Paulo, Ribeirão Preto, 2012. A O-Glicosilação com N-acetilglucosamina (O-GlcNAc) é uma modificação pós-traducional altamente dinâmica que modula diversas vias de sinalização. O processo de O-GlcNAc é controlado por duas enzimas: UDP-NAc transferase (OGT) e O-GlcNAcase (OGA). A enzima OGT catalisa a adição de N-acetil-glucosamina no grupo hidroxila dos resíduos de serina ou treonina das proteínas alvo. Por outro lado, a OGA catalisa a remoção hidrolítica de O-GlcNAc das proteínas modificadas. Proteínas com importante papel na função vascular são alvos da O-GlcNAc, e recentemente demonstramos que a expressão de proteínas modificadas com O-GlcNAc está aumentada em artérias de ratos com hipertensão DOCA-sal. Considerando que a produção de endotelina-1 (ET-1) encontra-se aumentada na vasculatura de diferentes modelos de hipertensão sensível ao sal, nós investigamos a hipótese de que o aumento da resposta vascular contrátil induzida pela ET-1 é decorrente da hiperativação da via RhoA/Rho cinase, mediada pelo aumento dos níveis de proteínas O-GlcNAc. Durante a realização de nossos experimentos, demonstramos que a exposição de aortas ou células do músculo liso vascular (CMLV) à ET-1 (0,1 mol/L) aumenta a vasoconstrição para fenilefrina (PE) e serotonina, bem como os níveis de proteínas O-GlcNAc, além de modular a expressão das enzimas OGT e OGA. A infusão de ET-1 (2 pmol/Kg/min) por 14 dias também promoveu aumento dos níveis vasculares de proteínas O-GlcNAc e da resposta contrátil da aorta à PE. O tratamento de aortas ou CMLV com ST045849 (inibidor da OGT, 100 µMol/L) ou atrasentan (antagonista do receptor ETA, 1 mol/L), preveniu o aumento dos níveis de proteínas O-GlcNAc induzido pela ET-1. Além disso, o tratamento com atrasentan por cinco semanas (atrasentan - 5 mg/kg/dia, por via oral) normalizou os níveis vasculares de proteínas O-GlcNAc em ratos DOCA-sal e também diminuiu a resposta contrátil da aorta à PE. A transfecção de CMLV com siRNA para OGT aboliu o efeito da ET-1 sobre os níveis de proteínas O-GlcNAc. Considerando que o aumento nas contrações da aorta à PE, após o tratamento com PUGNAc (inibidor seletivo da OGA) ou ET-1, foi abolido pelo inibidor de Rho cinase (Y-27632, 1 mol/L) e que a ET-1 ativa a via de sinalização da RhoA/Rho cinase, decidimos investigar se aumento dos níveis de proteínas O-GlcNAc ativa/modula a via RhoA/Rho cinase. A incubação de CMLV com ET-1 não mudou a expressão protéica das formas totais de ROCK-, ROCK-, CPI-17, MYPT-1 ou MLC, porém aumentou a expressão das formas fosforiladas da MYPT-1 (Tre853), CPI-17 (Tre38) e MLC (Tre18/Ser19). Estes efeitos não foram observados quando CMLV foram tratadas com ST045849, atrasentan ou previamente transfectadas com o siRNA para OGT. Também observamos que a ET-1 aumentou a atividade e a expressão protéica da RhoA, assim como a expressão da PDZ-Rho GEF e p115-Rho GEF. Este efeito foi abolido, quando CMLV foram previamente transfectadas com siRNA para OGT, incubadas com o inibidor da OGT ou tratadas com o antagonista de receptores ETA. Em conclusão, nossos dados fornecem evidências de que a ET-1 aumenta os níveis vasculares de proteínas O-GlcNAc, resultando na ativação da via RhoA/Rho cinase e no aumento da reatividade vascular. É possível que o aumento de proteínas O-GlcNAc, induzido pela ET-1, possa representar um novo mecanismo para a disfunção vascular induzida por este potente peptídeo. / LIMA, V.V. O-GlcNAcylation contributes to the vascular effects of ET-1 via activation of RhoA/Rho-kinase pathway. 2012. 106 f. Ph.D. Thesis - Faculdade de Medicina de Ribeirão Preto Universidade de São Paulo, Ribeirão Preto, 2012. Glycosylation with O-linked -N-acetylglucosamine (O-GlcNAc) is a highly dynamic post-translational modification that plays a key role in signal transduction pathways. The cycling of O-GlcNAc is controlled by two enzymes: UDP-NAc transferase (OGT) and O-GlcNAcase (OGA). Whereas OGT catalyses the addition of O-GlcNAc to the hydroxyl group of serine and threonine residues of a target protein, OGA catalyses the hydrolytic cleavage of O-GlcNAc from post-translationally-modified target. Proteins with an important role in vascular function are targets for O-GlcNAcylation and we have recently shown that the vascular content of O-GlcNAc-proteins is augmented in arteries from DOCA-salt rats. Since endothelin-1 (ET-1) production is increased in the vasculature of salt-sensitive forms of hypertension, we tested the hypothesis that O-GlcNAc contributes to the vascular effects of ET-1, via activation of the RhoA/Rho-kinase pathway. Incubation of rat aortas or vascular smooth muscle cells (VSMCs) with ET-1 (0,1 mol/L) produced a time-dependent increase in O-GlcNAc levels, decreased expression of O-GlcNAc transferase (OGT) and -N-acetylglucosaminidase (OGA), key enzymes in the O-GlcNAcylation process. Overnight treatment of aortas with ET-1 increased phenylephrine (PE) vasoconstriction. ET-1 effects were not observed when vessels were previously instilled with anti-OGT antibody or after incubation with an OGT inhibitor (ST045849, 100 mol/L). Aortas from DOCA-salt rats, which exhibit increased pre-pro-ET-1 expression, displayed increased contractions to PE and augmented levels of O-GlcNAc proteins. Treatment of DOCA-salt rats with atrasentan (ETA antagonist) abrogated augmented vascular levels of O-GlcNAc and prevented increased PE vasoconstriction. Aortas from rats chronically infused with low rate of ET-1 (2 pmol/Kg/min, 14days) exhibited increased O-GlcNAc-proteins and enhanced PE responses. These changes are similar to those induced by PUGNAc (OGA inhibitor which increases O-GlcNAc levels). ET-1 as well as PUGNAc augmented contractions to PE in endothelium-denuded rat aortas, an effect that was abolished by the Rho kinase inhibitor Y-27632 (1 mol/L). Incubation of VSMCs with ET-1 did not change expression of ROCK-, ROCK-, CPI-17, MYPT-1 or MLC, but increased phosphorylation levels of MYPT-1 (Thr853), CPI-17 (Thr38) and MLC (Thr18/Ser19). The effects of ET-1 on MYPT-1, CPI-17 and MLC phosphorylation were prevented by the OGT inhibitor and OGT siRNA transfection, as well as by atrasentan. ET-1 increased RhoA expression and activity in VSMCs, and this effect was abolished by OGT siRNA transfection and OGT inhibition. ET-1 also augmented expression of PDZ-Rho GEF and p115-Rho GEF in VSMCs and this was prevented by OGT siRNA, OGT inhibition (ST045849) and ETA receptor blockade (atrasentan, 1 mol/L). In conclusion, our data strongly suggest that ET-1 augments O-GlcNAc levels and this modification contributes to increase vascular contractile responses, via activation of the RhoA/Rho-kinase pathway. We speculate that the modulatory effect of ET-1 on O-GlcNAcylation may represent a novel mechanism underlying the vascular effects of the peptide.

In einem RT-PCR Ansatz aus neuronalen post mortem Gewebe des Menschen konnten EPB41 (Erythrozytäres Protein Bande 4.1) Spleißformen in verschiedenen Hirnregionen nachgewiesen werden. In einem weiteren RT-PCR Ansatz wurden höhermolekulare p4.1R-Spleißormen generiert, kloniert und zwei der erhaltenen Spleißformen (Klon 9 und Klon 13) charakterisiert. In einer In-situ-Hybridisierungsstudie an humanen Temporalkortex und Hippocampus konnten EPB41-Isoformen in fast allen Neuronen nachgewiesen werden. In immunhistochemischen Untersuchungen mit selbstgenerierten p4.1R spezifischen Antikörper wurden ebenfalls ausschließlich Neurone markiert. In proteinbiochemischen Untersuchungen konnte in verschiedenen humanen Hirnareale mit den p4.1R spezifischen Antikörpern eine 110 kDa und 120 kDa immunreaktive Bande nachgewiesen werden. In Experimenten an Primärkulturen von Rattenneuronen konnte eine Herunterregulation der p4.1R Proteine sowie der mRNA von p4.1R durch Verarmung des funktionellen Pools an G-Proteinen der Rho-Familie in der Zelle gezeigt werden. Die GTPasen der Rho-Familie regulieren unter anderem die Plastizität des Dendritenbaumes von Neuronen. / In a RT-PCR approach using human postmortem cerebral tissue from different brain regions several EPB41 (erythrocyte protein band 4.1) spliceforms could be generated. The amplificates were cloned and two of the highmolecular EPB41 spliceforms Klon 9 and Klon 13 were characterized. Klon 9 is a new spliceform, Klon13 is identical with EPB41 (accesion number AF156225). In an in situ hybridization study the EPB41 spliceforms were detected in almost all neurons of the temporal cortex and the hippocampus. Immunhistochemical localization of the p4.1R immunreactive proteins in human temporal cortex using p4.1R specific peptide antibodies, confirmed these results. The stning pattern of soma and dendrites of the neurones was punctuated. In Western Blot experiments a 110 kDa and 120 kDa p4.1R immunreactive proteinband was detected. A regulation of the protein 4.1R immunreactive proteins as well as the mRNA of protein 4.1 was found in experiments in which the functional pool of Rho GTPases in hippocampal primary neurones of the rat was manipulated.

Die Familie der ErbB-Rezeptor-Tyrosinkinasen besteht aus vier Mitgliedern, dem EGF-Rezeptor (ErbB-1), ErbB-2, ErbB-3 und ErbB-4. ErbB-Rezeptoren spielen eine wichtige Rolle bei der Entwicklung des Nervensystems, des Herzens und der Brustdrüsen. Ein Teil dieser Differenzierungsvorgänge läßt sich in vitro nachvollziehen: so ist zum Beispiel die Aktivierung des ErbB-2 Rezeptors ausreichend für alveoläre Morphogenese der Brustdrüsenepithelzellinie EpH4. Intrazelluläre Moleküle, die dieses ErbB2-Signal übertragen, sind allerdings noch unbekannt. Mit Hilfe eines neuen, modifizierten Hefe-2-Hybrid-Systems wurde in der vorliegenden Arbeit Vav2 als neuer Interaktionspartner von ErbB-2 identifiziert. Vav2 assoziiert mit aktiviertem ErbB-2 über eine SH2-Domäne. Die Interaktion ist direkt und ist von zwei Phosphotyrosinen in ErbB-2 abhängig. Vav2 kann den GDP/GTP-Austausch bei GTPasen der Rho-Familie vermitteln. Dadurch kann der Umbau des Zytoskeletts und Veränderungen der Transkription sowie Zelltransformation induziert werden. In einem dreidimensionalen Zellkultursystem kann aktiviertes Vav2 in EpH4 Zellen die Bildung von alveolären Zellaggregaten induzieren. In diesen Alveolen umgibt eine Schicht polarisierter milchproduzierender Zellen ein zentrales Lumen. Diese Vav2-vermittelte Morphogenese ist abhängig von der katalytischen GDP/GTP-Austausch Aktivität von Vav2. Katalytisch-inaktives Vav2 kann die morphogenetische Aktivität von ErbB-2 in EpH4-Zellen verhindern, ohne die mitogene Aktivität von ErbB-2 zu beeinflussen. Vav2 ist mit ErbB-2 coexprimiert und interagiert mit dem Rezeptor in Brustdrüsenzellen schwangerer Mäuse. Diese Untersuchungen deuten darauf hin, dass Vav2 eine wichtige Funktion bei der durch ErbB-2 induzierten alveolären Morphogenese der Brustdrüse spielt. / The ErbB receptor tyrosine kinases constitute a subfamily of four structurally related members, the EGF receptor (ErbB-1), ErbB-2, ErbB-3 and ErbB-4. ErbB receptor tyrosine kinases are critical for embryonic development of central and peripheral neural structures and heart. In addition, ErbB receptors play an important role in the postnatal development of the mammary gland. Previous studies showed that activated ErbB-2 receptor induces alveolar morphogenesis of EpH4 mammary epithelial cells that are cultured on a three-dimensional matrix (termed Matrigel). However, the downstream signaling proteins that mediate this biological activity of ErbB-2 were unknown. In this work, Vav2 was identified as a direct interaction partner of tyrosine-phosphorylated ErbB receptors using the yeast two-hybrid system. Vav2 is a member of a family of guanine nucleotide exchange factors that induce cytoskeletal rearrangements, transcriptional alterations, and have oncogenic potential when activated. To test the ability of Vav2 to mediate morphogenic signals of ErbB-2, EpH4 cells overexpressing Vav2 protein were cultured on Matrigel. Indeed, Vav2 induces alveolar morphogenesis of EpH4 cells when activated either by oncogenic mutation or tyrosine phosphorylation by ErbB-2. The morphogenic activity of Vav2 requires the Dbl homology domain, which mediates GDP/GTP exchange. Dominant-negative Vav2 specifically blocks the morphogenic signals of ErbB-2 in EpH4 cells without interfering with ErbB2-induced mitogenesis. Importantly, Vav2 is co-expressed and interacts with ErbB-2 in the mammary glands of pregnant mice. Taken together, these results point to Vav2 as a candidate to mediate ErbB-2 signals for alveolar morphogenesis in vivo, which is a relevant step in the development of the mammary gland during pregnancy.

INTRODUÇÃO: Indivíduos com asma possuem infiltração aumentada de células inflamatórias, produção de quimiocinas e hiperresponsividade de vias aéreas. Estes apresentam níveis aumentados de interleucina (IL)-17, importante na regulação da expressão de mediadores inflamatórios e recrutamento de células inflamatórias, outra característica é aumento da atividade da proteína Rho-quinase em suas vias aéreas. A modulação da IL-17 e da proteína Rho-quinase pode ser promissora para o tratamento desta doença. OBJETIVO: Estudar os efeitos dos tratamentos realizados com anticorpo neutralizador anti-IL17 e do inibidor da Rho-quinase, associados ou não, em camundongos com inflamação pulmonar alérgica crônica. MÉTODOS: Foram utilizados 64 camundongos BALB/c, divididos em 8 grupos (8 animais por grupo): SAL (solução salina); OVA (ovoalbumina), SAL-RHOi (salina e inibidor de Rho-quinase), OVA - RHOi (ovoalbumina e inibidor de Rho-quinase), SAL - anti-IL17 (salina e anti-IL17), OVA - anti-IL17 (ovoalbumina e anti-IL17), SAL - RHOi - anti-IL17 (salina, anti-IL17 e inibidor de Rho-quinase), OVA - RHOi - anti-IL17 (ovoalbumina, anti-IL17 e inibidor de Rho-quinase). O protocolo de sensibilização e indução da inflamação pulmonar por ovoalbumina teve duração de 28 dias. O Anti-IL17A (clone 50104 - 7,5 ug por dose) foi administrado via intraperitoneal e inibidor de Rho-quinase (Y-27632) intranasal (10 mg/kg), 1h antes de cada desafio com ovoalbumina (22, 24, 26 e 28 dias). RESULTADOS: Houve um aumento na resistência do sistema respiratório e na elastância, nos marcadores inflamatórios CD4+, CD8+, ROCK1 e ROCK2, IL-1-beta, IL-2, IL-4, IL-5, IL-6, IL-10, IL-13, IL-17, TNFalfa, em vias sinalizadoras NF-kappaB, FOXP-3 e células dendríticas, em marcadores de remodelamento MMP9, MMP12, TIMP1, iNOS, TGF-beta, no conteúdo de isoprostano, decorina, biglicano, fibronectina e fibras colágenas e na expressão gênica de VAChT, IL-17 e arginase, no grupo OVA em comparação com o grupo controle. O tratamento dos animais sensibilizados, de forma individualizada ou a associação dos dois, atenuou estas respostas quando comparados ao grupo sensibilizado com ovoalbumina e não tratado (p < 0,05). O tratamento do inibidor de Rho-quinase associado ao anti-IL17 gerou potencialização do controle da resposta de hiperresponsividade à metacolina, assim como nas vias aéreas a redução do número de células positivas TNF-alfa, IL-4, IL-5 e nos septos alveolares o número de células positivas IL-4, IL-5, TGF-beta, FOXP3, ROCK1 e ROCK2 (p < 0,05). CONCLUSÃO: O tratamento com anti-IL17 associado ao inibidor da Rho-quinase modula a hiperresponsividade das vias aéreas, inflamação, e remodelamento e estresse oxidativo em animais com inflamação pulmonar alérgica crónica / RATIONALE: Individuals with asthma have increased infiltration of inflammatory cells, chemokines production, and airway hyperresponsiveness. Asthmatics have elevated levels of interleukin (IL)-17, which plays an important role in regulating the expression of inflammatory mediators and recruitment of inflammatory cells, these individuals also have increased Rho-kinase protein activity in their airways. The modulation of IL-17 and Rho-kinase protein may be promising for the treatment of this disease. OBJECTIVE: To study the effects of anti-IL17 neutralizing antibody and Rho-kinase inhibitor treatments, associated or not, on mice with chronic allergic lung inflammation. METHODS: Were used 64 BALB/c mice, divided into eight groups (n=8 in each group): SAL (saline-instilled); OVA (exposed-ovalbumin); SAL-RHOi (saline and Rho-kinase inhibitor), OVA-RHOi (exposed-ovalbumin and Rho-kinase inhibitor); SAL - anti-IL17 (saline and anti-IL17), OVA - anti-IL17 (exposed-ovalbumin and anti-IL17); SAL - RHOi -anti-IL17(saline, Rho-kinase inhibitor and anti-IL17), OVA - RHOi - anti-IL17 (exposed-ovalbumin, anti-IL17 and Rho kinase inhibitor). The protocol for sensitization and induction of pulmonary inflammation by ovalbumin has the duration of 28 days. The Anti-IL17A neutralizing antibody (clone 50104-7.5 ug per dose) was administered via the intraperitoneal, and Rho-kinase inhibitor (Y-27632) intranasal (10 mg/kg), 1h before each ovalbumin challenge (22, 24, 26 and 28 day). RESULTS: There was an increase in respiratory system resistence and elastance, in the positive cells evaluated CD4+, CD8+, ROCK1 and ROCK2, IL-1beta, IL-2, IL-4, IL-5, IL-6, IL-10, IL-13, IL-17, TNFalpha, TGF-beta, MMP9, MMP12, TIMP1 and isoprostane, decorin, biglican, fibronectin, collagen fibers content, signaling pathways NF-kappaB, FOX-P3, dendrict cells and gene expression of VAChT, IL-17 and arginase in the OVA group compared to the control group. Treatment of the sensitized animals with the Rho-kinase inhibitor or with the anti-IL17 or with the combination of the two, attenuated these responses when compared to the ovalbumin-sensitized and untreated group (p < 0,05). The treatment of the anti-IL17 associated Rho-kinase inhibitor generated potentiation of the hyper responsiveness response to methacholine, as well as in the airways the reduction of the number of TNF-alpha, IL-4, IL-5 positive cells and in the alveolar septa the number of IL-4, IL-5, FOXP3, TGF-beta, ROCK1 and ROCK2 (p < 0.05). CONCLUSION: Anti-IL17 treatment associated with the Rho-kinase inhibitor modulates airway hyperresponsiveness, inflammation, remodeling and oxidative stress in animals with chronic allergic pulmonary inflammation

La Radiothérapie occupe la deuxième place dans la liste de traitement du cancer le plus important après chirurgie. Le progrès technique récent, comme la radiothérapie avec modulation d'intensité (IMRT) ou la radiothérapie guidée par l'image (IGRT), en combinaison avec de nouveaux médicaments à action spécifique tels que les anticorps monoclonaux, sont une garantie d'augmentation de l'index thérapeutique. Cependant, la radiothérapie peut provoquer un’ altération du processus normal de réparation et d'induire le développement d'un cadre de fibrose dans un sous-ensemble de patients sensibles et dans les survivants à long terme au cancer. La principale caractéristique de la fibrose radio-induit est l'accumulation excessive et anormale de collagène composé principalement des éléments fibrillaire et immatures de la matrice extracellulaire (ECM).Les organes qui peuvent être touchés par ce phénomène sont le foie, la peau, les intestins, les reins et les poumons. D'un point de vue clinique, la fibrose peut être considérée comme une condition irréversible, sans solution. Nous et d'autres ont récemment montré que, outre l'activation de la TGF-β/Smad canonique, d'autres voies sont activées dans les tissus fibreux tels que la cascade de signalisation intracellulaire Rho/ROCK. Fait intéressant, la façon dont Rho/ROCK semble spécifiquement activé dans la fibrose intestinale radio-induite, fournis une justification pour un stratégie anti-fibrotique ciblé. L’ inhibition pharmacologique de Rho avec les statines, en fait, est en mesure de prévenir et même inverser les phénomènes de fibrose post-actinique intestinale.Avec ces prémisses, dans nos études, nous avons montré le rôle des statines (Simvastatine et Pravastatine) et d'un inhibiteur spécifique de ROCK (Y-27632) dans un modèle murin de fibrose pulmonaire obtenue avec une approche pharmacologique (Bléomycine - BLM) . Par la suite, nous avons développé un modèle de fibrose pulmonaire induite par l'irradiation complet du thorax et évalué la réponse à l'administration de la Pravastatine. La confirmation de la participation de la voie Rho/ROCK/CTGF dans la fibrose pulmonaire a été montré par immunohistochimie: le traitement à la Pravastatine normalise l'expression de trois marqueurs: RhoB, TGFβ-RII et CTGF.Après, dans deux modèles de fibrose radio-induite (intestinal et pulmonaire), nous avons analysé, grâce à l’immunohistochimie, les mécanismes sous-jacents l'action antifibrotique de la Pravastatine via l’axe MMP2-TIMP2. Très intéressant, quand la pravastatine a été administré à titre préventif ou curatif, nous avons trouvé un impact différent sur la fibrolyse.Enfin, in vitro, nous avons étudié par zymographie l'expression des gélatinases (MMP2 et MMP9) dans des cultures primaires des fibroblastes pulmonaire murins exposées à différentes doses de rayonnement et de Pravastatine. Le métalloprotéases semble être à son tour impliquée dans les mécanismes pro-fibrolytiques induits par les statines.Dans notre modèle animal de fibrose pulmonaire, la Pravastatine est capable d'inverser le processus fibrotique et les métalloprotéases semblent être impliqués à leur tour, in vivo et in vitro, dans les mécanismes pro-fibrolyse induits par le médicament.La multiplicité des acteurs impliqués dans la physiopathologie de lésions fibrotiques explique pourquoi la mise en place d'une stratégie thérapeutique efficace est si complexe. La recherche dans les processus mécaniques de dommages aux tissus normaux ont ouvert la voie à de nouvelles approches thérapeutiques. Ces nouvelles cibles comprennent la réduction de l’inflammation, de l'activation vasculaire et de la thrombose, ainsi que la découverte de nouvelles cibles moléculaires. Il existe une variété de modèles précliniques et des stratégies efficaces, mais de nombreux efforts doivent être déployés pour atteindre l'objectif difficile de protéger les tissus normaux des effets secondaires de la radiothérapie. / Radiotherapy is the second most important treatment modality after surgery in the treatment of cancer. Recent technical advancements, such as intensity-modulated radiation therapy (IMRT) or image-guided radiation therapy (IGRT), combined with new targeted drugs have significant promise for therapeutic outcome. However radiation treatment could result in disabling normal tissue injury and in the development of progressive fibrosis in a subset of sensitive patients and in long-term cancer survivors. The main feature of tissue fibrosis is excessive accumulation of abnormal and cross-linked collagen mainly composed of fibrillar and immature extracellular matrix (ECM) components.The organs that can be affected by this phenomenon are liver, skin, intestine, kidneys and lungs. From a clinical point of view, fibrosis can be seen as an irreversible condition, without solution. We and others recently showed that beside the activation of the canonical TGF-β/Smad pathway, other intracellular signaling cascades including the Rho/ROCK pathway are switched on in fibrotic tissues. Interestingly, the Rho/ROCK pathway seems differentially activated in radiation-induced intestinal fibrosis, thereby providing a rationale for a specific, targeted anti-fibrotic strategy. Pharmacological inhibition of Rho using statins indeed prevent and even reverse intestinal radiation fibrosis.In our studies, we showed the role of Statin (Pravastatin e Simvastatin) and a specific inhibitor ROCK inhibitors (Y-27632) in a mice model of pulmonary induced-fibrosis obtained by a pharmacological approach (Bleomycin – BLM). Indeed, we developed a model of lung fibrosis by complete irradiation of chest and tested Pravastatin action. Confirmation of the involvement of Rho/ROCK/CTGF pathway in lung fibrosis are shown by immunohistochemistry: Pravastatin-treament normalized the expression of three markers: RhoB, TGF-RII and CTGF.Then, in models of radiation induced gut and lung fibrosis, we analysed, from a immunohistological point of view, the underlying mechanisms of the antifibrotic action of Pravastatin via MMP2-TIMP2 axis. Interestingly we found a different impact on fibrolysis when Pravastatin was administered preventively or curatively.Finally, in vitro, we investigate by zymography the expression of Gelatinases (MMP2 and MMP9) in primary lung fibroblasts cultures exposure at the different radiation and Pravastatin doses. Metalloproteases would appear to be in turn involved in pro-fibrolytic mechanisms induced by statin.The multiplicity of actors involved in the pathogenesis of fibrotic lesions explains why the definition of an effective therapeutic strategy is so complex.Researches in mechanistic processes of normal tissue damage paved the way for new therapeutic approaches. These new targets include reduction of vascular activation, inflammation and thrombosis and new molecular targets definition. Effective strategies are multiple on preclinical models, but numerous efforts have to be made to achieve the complicated goal of protection of normal tissues from the side effects of radiation therapy. / La radioterapia è la seconda modalità di trattamento più importante dopo chirurgia neltrattamento delle neoplasie. I recenti progressi tecnici, come la terapia ad intensità modulata(IMRT) o l’image-guided radioterapia (IGRT), in combinazione con nuovi farmaci ad azionemirata come gli anticorpi monoclonali, costituiscono ulteriore garanzia di incrementodell’indice terapeutico. Tuttavia il trattamento radiante può causare un’alterazione delnormale processo di riparazione e indurre lo sviluppo di un quadro di fibrosi in unsottogruppo di pazienti sensibili e nei lungo-sopravviventi al cancro. La caratteristicacardinale della fibrosi radioindotta è l’eccessivo ed anomalo accumulo di collagene compostoprincipalmente di componenti fibrillari e immature della matrice extracellulare (ECM).Gli organi che possono essere interessati da questo fenomeno sono fegato, pelle,intestino, reni e polmoni. Da un punto di vista clinico, la fibrosi può essere vista come unacondizione irreversibile, senza soluzione. Noi ed altri recentemente abbiamo mostrato cheaccanto alla attivazione della via canonica TGF-β/Smad, altre vie vengono attivate nei tessutifibrotici come la cascata di segnalazione intracellulare della via Rho/ROCK. Interessantenotare che la via Rho/ROCK sembra specificatamente attivata nella radiazione indotta fibrosiintestinale, fornendo così una spiegazione razionale per una specifica, mirata strategia antifibrotica.L'inibizione farmacologica di Rho con le statine infatti è in grado di prevenire eaddirittura invertire i fenomeni di fibrosi intestinale post-attinica.Grazie a queste premesse, nei nostri studi, abbiamo mostrato il ruolo delle statine(Pravastatina e Simvastatina) e di uno specifico inibitore di ROCK (Y-27632) in un modellomurino di fibrosi polmonare indotta ottenuto con un approccio farmacologico (bleomicina -BLM). In seguito, abbiamo sviluppato un modello di fibrosi polmonare indottadall’irradiazione completa del torace e valutata la risposta alla somministrazione dellaPravastatina. In questo modello ed in un modello di fibrosi intestinale indotto da radiazioni,abbiamo analizzato, da un punto di vista immunoistologico, i meccanismi sottostanti l'azione9antifibrotica della pravastatina e il ruolo delle metalloproteasi (MMP2 e TIMP2). Infine, invitro, abbiamo indagato, mediante zimografia, l'espressione delle gelatinasi (MMP2 e MMP9)in culture primarie di fibroblasti polmonari murini esposti a differenti dosi di radiazione epravastatina.Nel nostro modello animale di fibrosi polmonare, la Pravastatina è in grado di renderereversibile il processo fibrotico e le metalloproteasi parrebbero essere a loro volta coinvolte,in vivo and in vitro, nei meccanismi pro-fibrolitici indotti dal farmaco.La molteplicità di attori coinvolti nella patogenesi delle lesioni fibrotiche spiegaperché la definizione di una strategia terapeutica efficace è così complessa. Ricerche neiprocessi meccanicistici di danno ai tessuti normali hanno aperto la strada a nuovi approcciterapeutici. Questi nuovi obiettivi comprendono la riduzione dell’ attivazione vascolare,dell'infiammazione e della trombosi, oltre alla definizione di nuovi target molecolari. Esistonomolteplici ed efficaci strategie su modelli preclinici, ma numerosi sforzi devono essere fattiper raggiungere il complicato obiettivo di proteggere i tessuti normali dagli effetti collateralidella radioterapia.

La fibrose radio-induite est une complication sévère et tardive de la radiothérapie. Plusieurs études cliniques ont montré que la combinaison pentoxifylline-vitamine E est un traitement sûr et efficace contre la fibrose. Cependant, les mécanismes moléculaires de son efficacité restent inexplorés. Nous avons montré l’efficacité de la combinaison pentoxifylline-vitamine E dans l’entéropathie radique dans une faisabilité clinique. En parallèle, en utilisant un modèle unique, in vitro, de cellules musculaires lisses intestinales primaires isolées des personnes atteintes de l’entéropathie radique, nous avons montré une synergie entre la pentoxifylline et l’analogue hydrophile de vitamine E (trolox) qui permet à l’association d’inhiber l’expression de TGF-β1 au niveau de l’ARN messager et de la protéine. Cette action inhibitrice intervient au niveau transcriptionnel et conduit à une inhibition conséquente des cibles de la voie de signalisation TGF-β1/Smad (Col Iα1, FN1, PAI-1, CTGF), alors qu’elle semble sans effet sur la voie de signalisation Rho/ROCK. Pour la première fois, dans ces cellules issues de l’entéropathie radique, nous avons montré une surexpression de miR-210 ; microRNA induit par l’hypoxie. L’association pentoxifylline-trolox inverse la surexpression de miR-210 aussi bien dans les conditions normoxique que dans les conditions hypoxiques. L’implication de miR-210 dans l’entéropathie radique n’a pas été préalablement étudiée, néanmoins nous avons montré qu’un inhibiteur de miR-210 diminue l’expression de Col Iα1 dans ce modèle. L’effet anti-fibrosant exercé par l’association pentoxifylline-vitamine E est partiellement induit par l’inhibition de la cascade TGF-β1. L’inhibition de miR-210 est un deuxième mécanisme potentiel nécessitant d’autres investigations. Cette étude renforce les essais clinique antérieurs en montrant in vitro une synergie entre pentoxifylline et vitamine E et permettant de proposer cette association en première ligne thérapeutique dans la fibrose radio-induite. De plus, miR-210 est proposé comme une possible cible thérapeutique pour traiter la fibrose radio-induite. / Radiation-induced fibrosis is a serious late complication of radiotherapy. Pentoxifylline-vitamin E has proven effective and safe in clinical trials as treatment of fibrosis, while the molecular mechanism of its activity is yet unexplored. We showed efficacy of Pentoxifylline-vitamin E combination in radiation-induced enteropathy in a small clinical study. In parallel, using a unique in vitro model of primary smooth muscle cells isolated from intestinal samples isolated from humans with radiation enteropathy we showed that pentoxifylline and the hydrophilic analogous of vitamin E (trolox) synergize to inhibit TGF-β1 protein and mRNA expression. This inhibitory action is mediated at the transcriptional level and leads to subsequent inhibition of TGF-β1/Smad targets (Col Iα1, FN1, PAI-1, CTGF), while it has no effect on the Rho/Rock pathway. We have also demonstrated, for the first time, an overexpression of the hypoxia-induced microRNA miR-210 in the fibrotic cells. Pentoxifylline-trolox combination could reverse this miR-210 overexpression in normoxic and hypoxic conditions. While miR-210 has not been previously shown to be involved in radiation-induced enteropathy, we showed that miR-210 inhibitor could reduce mRNA expression of Col Iα1. The anti-fibrotic effect of combined pentoxifylline-vitamin E is at least in part mediated by inhibition of the TGF-β1 cascade. MiR-210 inhibition is another mechanism which needs further investigations. This study strengthens previous clinical data showing pentoxifylline-vitamin E synergy and supports its use as a first-line treatment of radiation-induced fibrosis. Also, it suggests miR-210 as a new potential therapeutic target for the treatment of this complication.

INTRODUÇÃO: Indivíduos com asma possuem infiltração aumentada de células inflamatórias, produção de quimiocinas e hiperresponsividade de vias aéreas. Estes apresentam níveis aumentados de interleucina (IL)-17, importante na regulação da expressão de mediadores inflamatórios e recrutamento de células inflamatórias, outra característica é aumento da atividade da proteína Rho-quinase em suas vias aéreas. A modulação da IL-17 e da proteína Rho-quinase pode ser promissora para o tratamento desta doença. OBJETIVO: Estudar os efeitos dos tratamentos realizados com anticorpo neutralizador anti-IL17 e do inibidor da Rho-quinase, associados ou não, em camundongos com inflamação pulmonar alérgica crônica. MÉTODOS: Foram utilizados 64 camundongos BALB/c, divididos em 8 grupos (8 animais por grupo): SAL (solução salina); OVA (ovoalbumina), SAL-RHOi (salina e inibidor de Rho-quinase), OVA - RHOi (ovoalbumina e inibidor de Rho-quinase), SAL - anti-IL17 (salina e anti-IL17), OVA - anti-IL17 (ovoalbumina e anti-IL17), SAL - RHOi - anti-IL17 (salina, anti-IL17 e inibidor de Rho-quinase), OVA - RHOi - anti-IL17 (ovoalbumina, anti-IL17 e inibidor de Rho-quinase). O protocolo de sensibilização e indução da inflamação pulmonar por ovoalbumina teve duração de 28 dias. O Anti-IL17A (clone 50104 - 7,5 ug por dose) foi administrado via intraperitoneal e inibidor de Rho-quinase (Y-27632) intranasal (10 mg/kg), 1h antes de cada desafio com ovoalbumina (22, 24, 26 e 28 dias). RESULTADOS: Houve um aumento na resistência do sistema respiratório e na elastância, nos marcadores inflamatórios CD4+, CD8+, ROCK1 e ROCK2, IL-1-beta, IL-2, IL-4, IL-5, IL-6, IL-10, IL-13, IL-17, TNFalfa, em vias sinalizadoras NF-kappaB, FOXP-3 e células dendríticas, em marcadores de remodelamento MMP9, MMP12, TIMP1, iNOS, TGF-beta, no conteúdo de isoprostano, decorina, biglicano, fibronectina e fibras colágenas e na expressão gênica de VAChT, IL-17 e arginase, no grupo OVA em comparação com o grupo controle. O tratamento dos animais sensibilizados, de forma individualizada ou a associação dos dois, atenuou estas respostas quando comparados ao grupo sensibilizado com ovoalbumina e não tratado (p < 0,05). O tratamento do inibidor de Rho-quinase associado ao anti-IL17 gerou potencialização do controle da resposta de hiperresponsividade à metacolina, assim como nas vias aéreas a redução do número de células positivas TNF-alfa, IL-4, IL-5 e nos septos alveolares o número de células positivas IL-4, IL-5, TGF-beta, FOXP3, ROCK1 e ROCK2 (p < 0,05). CONCLUSÃO: O tratamento com anti-IL17 associado ao inibidor da Rho-quinase modula a hiperresponsividade das vias aéreas, inflamação, e remodelamento e estresse oxidativo em animais com inflamação pulmonar alérgica crónica / RATIONALE: Individuals with asthma have increased infiltration of inflammatory cells, chemokines production, and airway hyperresponsiveness. Asthmatics have elevated levels of interleukin (IL)-17, which plays an important role in regulating the expression of inflammatory mediators and recruitment of inflammatory cells, these individuals also have increased Rho-kinase protein activity in their airways. The modulation of IL-17 and Rho-kinase protein may be promising for the treatment of this disease. OBJECTIVE: To study the effects of anti-IL17 neutralizing antibody and Rho-kinase inhibitor treatments, associated or not, on mice with chronic allergic lung inflammation. METHODS: Were used 64 BALB/c mice, divided into eight groups (n=8 in each group): SAL (saline-instilled); OVA (exposed-ovalbumin); SAL-RHOi (saline and Rho-kinase inhibitor), OVA-RHOi (exposed-ovalbumin and Rho-kinase inhibitor); SAL - anti-IL17 (saline and anti-IL17), OVA - anti-IL17 (exposed-ovalbumin and anti-IL17); SAL - RHOi -anti-IL17(saline, Rho-kinase inhibitor and anti-IL17), OVA - RHOi - anti-IL17 (exposed-ovalbumin, anti-IL17 and Rho kinase inhibitor). The protocol for sensitization and induction of pulmonary inflammation by ovalbumin has the duration of 28 days. The Anti-IL17A neutralizing antibody (clone 50104-7.5 ug per dose) was administered via the intraperitoneal, and Rho-kinase inhibitor (Y-27632) intranasal (10 mg/kg), 1h before each ovalbumin challenge (22, 24, 26 and 28 day). RESULTS: There was an increase in respiratory system resistence and elastance, in the positive cells evaluated CD4+, CD8+, ROCK1 and ROCK2, IL-1beta, IL-2, IL-4, IL-5, IL-6, IL-10, IL-13, IL-17, TNFalpha, TGF-beta, MMP9, MMP12, TIMP1 and isoprostane, decorin, biglican, fibronectin, collagen fibers content, signaling pathways NF-kappaB, FOX-P3, dendrict cells and gene expression of VAChT, IL-17 and arginase in the OVA group compared to the control group. Treatment of the sensitized animals with the Rho-kinase inhibitor or with the anti-IL17 or with the combination of the two, attenuated these responses when compared to the ovalbumin-sensitized and untreated group (p < 0,05). The treatment of the anti-IL17 associated Rho-kinase inhibitor generated potentiation of the hyper responsiveness response to methacholine, as well as in the airways the reduction of the number of TNF-alpha, IL-4, IL-5 positive cells and in the alveolar septa the number of IL-4, IL-5, FOXP3, TGF-beta, ROCK1 and ROCK2 (p < 0.05). CONCLUSION: Anti-IL17 treatment associated with the Rho-kinase inhibitor modulates airway hyperresponsiveness, inflammation, remodeling and oxidative stress in animals with chronic allergic pulmonary inflammation

LIMA, V.V. Papel da O-glicosilação com N-acetil-glucosamina (O-GlcNAc) nas alterações vasculares associadas a altos níveis de endotelina-1. 2012. 106 f. Tese (Doutorado) - Faculdade de Medicina de Ribeirão Preto Universidade de São Paulo, Ribeirão Preto, 2012. A O-Glicosilação com N-acetilglucosamina (O-GlcNAc) é uma modificação pós-traducional altamente dinâmica que modula diversas vias de sinalização. O processo de O-GlcNAc é controlado por duas enzimas: UDP-NAc transferase (OGT) e O-GlcNAcase (OGA). A enzima OGT catalisa a adição de N-acetil-glucosamina no grupo hidroxila dos resíduos de serina ou treonina das proteínas alvo. Por outro lado, a OGA catalisa a remoção hidrolítica de O-GlcNAc das proteínas modificadas. Proteínas com importante papel na função vascular são alvos da O-GlcNAc, e recentemente demonstramos que a expressão de proteínas modificadas com O-GlcNAc está aumentada em artérias de ratos com hipertensão DOCA-sal. Considerando que a produção de endotelina-1 (ET-1) encontra-se aumentada na vasculatura de diferentes modelos de hipertensão sensível ao sal, nós investigamos a hipótese de que o aumento da resposta vascular contrátil induzida pela ET-1 é decorrente da hiperativação da via RhoA/Rho cinase, mediada pelo aumento dos níveis de proteínas O-GlcNAc. Durante a realização de nossos experimentos, demonstramos que a exposição de aortas ou células do músculo liso vascular (CMLV) à ET-1 (0,1 mol/L) aumenta a vasoconstrição para fenilefrina (PE) e serotonina, bem como os níveis de proteínas O-GlcNAc, além de modular a expressão das enzimas OGT e OGA. A infusão de ET-1 (2 pmol/Kg/min) por 14 dias também promoveu aumento dos níveis vasculares de proteínas O-GlcNAc e da resposta contrátil da aorta à PE. O tratamento de aortas ou CMLV com ST045849 (inibidor da OGT, 100 µMol/L) ou atrasentan (antagonista do receptor ETA, 1 mol/L), preveniu o aumento dos níveis de proteínas O-GlcNAc induzido pela ET-1. Além disso, o tratamento com atrasentan por cinco semanas (atrasentan - 5 mg/kg/dia, por via oral) normalizou os níveis vasculares de proteínas O-GlcNAc em ratos DOCA-sal e também diminuiu a resposta contrátil da aorta à PE. A transfecção de CMLV com siRNA para OGT aboliu o efeito da ET-1 sobre os níveis de proteínas O-GlcNAc. Considerando que o aumento nas contrações da aorta à PE, após o tratamento com PUGNAc (inibidor seletivo da OGA) ou ET-1, foi abolido pelo inibidor de Rho cinase (Y-27632, 1 mol/L) e que a ET-1 ativa a via de sinalização da RhoA/Rho cinase, decidimos investigar se aumento dos níveis de proteínas O-GlcNAc ativa/modula a via RhoA/Rho cinase. A incubação de CMLV com ET-1 não mudou a expressão protéica das formas totais de ROCK-, ROCK-, CPI-17, MYPT-1 ou MLC, porém aumentou a expressão das formas fosforiladas da MYPT-1 (Tre853), CPI-17 (Tre38) e MLC (Tre18/Ser19). Estes efeitos não foram observados quando CMLV foram tratadas com ST045849, atrasentan ou previamente transfectadas com o siRNA para OGT. Também observamos que a ET-1 aumentou a atividade e a expressão protéica da RhoA, assim como a expressão da PDZ-Rho GEF e p115-Rho GEF. Este efeito foi abolido, quando CMLV foram previamente transfectadas com siRNA para OGT, incubadas com o inibidor da OGT ou tratadas com o antagonista de receptores ETA. Em conclusão, nossos dados fornecem evidências de que a ET-1 aumenta os níveis vasculares de proteínas O-GlcNAc, resultando na ativação da via RhoA/Rho cinase e no aumento da reatividade vascular. É possível que o aumento de proteínas O-GlcNAc, induzido pela ET-1, possa representar um novo mecanismo para a disfunção vascular induzida por este potente peptídeo. / LIMA, V.V. O-GlcNAcylation contributes to the vascular effects of ET-1 via activation of RhoA/Rho-kinase pathway. 2012. 106 f. Ph.D. Thesis - Faculdade de Medicina de Ribeirão Preto Universidade de São Paulo, Ribeirão Preto, 2012. Glycosylation with O-linked -N-acetylglucosamine (O-GlcNAc) is a highly dynamic post-translational modification that plays a key role in signal transduction pathways. The cycling of O-GlcNAc is controlled by two enzymes: UDP-NAc transferase (OGT) and O-GlcNAcase (OGA). Whereas OGT catalyses the addition of O-GlcNAc to the hydroxyl group of serine and threonine residues of a target protein, OGA catalyses the hydrolytic cleavage of O-GlcNAc from post-translationally-modified target. Proteins with an important role in vascular function are targets for O-GlcNAcylation and we have recently shown that the vascular content of O-GlcNAc-proteins is augmented in arteries from DOCA-salt rats. Since endothelin-1 (ET-1) production is increased in the vasculature of salt-sensitive forms of hypertension, we tested the hypothesis that O-GlcNAc contributes to the vascular effects of ET-1, via activation of the RhoA/Rho-kinase pathway. Incubation of rat aortas or vascular smooth muscle cells (VSMCs) with ET-1 (0,1 mol/L) produced a time-dependent increase in O-GlcNAc levels, decreased expression of O-GlcNAc transferase (OGT) and -N-acetylglucosaminidase (OGA), key enzymes in the O-GlcNAcylation process. Overnight treatment of aortas with ET-1 increased phenylephrine (PE) vasoconstriction. ET-1 effects were not observed when vessels were previously instilled with anti-OGT antibody or after incubation with an OGT inhibitor (ST045849, 100 mol/L). Aortas from DOCA-salt rats, which exhibit increased pre-pro-ET-1 expression, displayed increased contractions to PE and augmented levels of O-GlcNAc proteins. Treatment of DOCA-salt rats with atrasentan (ETA antagonist) abrogated augmented vascular levels of O-GlcNAc and prevented increased PE vasoconstriction. Aortas from rats chronically infused with low rate of ET-1 (2 pmol/Kg/min, 14days) exhibited increased O-GlcNAc-proteins and enhanced PE responses. These changes are similar to those induced by PUGNAc (OGA inhibitor which increases O-GlcNAc levels). ET-1 as well as PUGNAc augmented contractions to PE in endothelium-denuded rat aortas, an effect that was abolished by the Rho kinase inhibitor Y-27632 (1 mol/L). Incubation of VSMCs with ET-1 did not change expression of ROCK-, ROCK-, CPI-17, MYPT-1 or MLC, but increased phosphorylation levels of MYPT-1 (Thr853), CPI-17 (Thr38) and MLC (Thr18/Ser19). The effects of ET-1 on MYPT-1, CPI-17 and MLC phosphorylation were prevented by the OGT inhibitor and OGT siRNA transfection, as well as by atrasentan. ET-1 increased RhoA expression and activity in VSMCs, and this effect was abolished by OGT siRNA transfection and OGT inhibition. ET-1 also augmented expression of PDZ-Rho GEF and p115-Rho GEF in VSMCs and this was prevented by OGT siRNA, OGT inhibition (ST045849) and ETA receptor blockade (atrasentan, 1 mol/L). In conclusion, our data strongly suggest that ET-1 augments O-GlcNAc levels and this modification contributes to increase vascular contractile responses, via activation of the RhoA/Rho-kinase pathway. We speculate that the modulatory effect of ET-1 on O-GlcNAcylation may represent a novel mechanism underlying the vascular effects of the peptide.