Résumé : La variation de la [Ca2+] intracellulaire participe à nombreux de processus biologiques. Les cellules eucaryotes expriment à la membrane plasmique une variété de canaux par lesquelles le calcium peut entrer. Dans les cellules non excitables, deux mécanismes principaux permettent l'entrée calcique; l'entrée capacitative de Ca2+ via Orai1 (SOCE) et l'entrée calcique activé par un récepteur (ROCE). Plusieurs protéines clés sont impliquées dans la régulation de ces voies d'entrée calcique, ainsi que dans l'homéostasie calcique. TRPC6 est un canal calcique impliquée dans l'entrée calcique dans les cellules à la suite d’une stimulation d’un récepteur hormonal. TRPC6 transloque à la membrane cellulaire et il y demeure jusqu'à ce que le stimulus soit retiré. Les mécanismes qui régulent le trafic et l'activation de TRPC6 sont cependant encore peu connus. Des découvertes récentes ont démontré qu'il y a un rôle potentiel de Rho kinase dans l'activité de TRPC6. Rho kinase est activée par la petite protéine G RhoA qui peut être activée par les protéines G hétérotrimériques Gα12 et Gα13. En plus de Gα12 et Gα13, les protéines de désensibilisation des GPCR β -arrestin 1 et / ou β-arrestin 2 peuvent aussi activer RhoA. Le but de notre étude est d'examiner la participation des protéines Gα12/13 et β-arrestin 1/ β-arrestin 2 dans l'activation de TRPC6 et de la protéine Orai1. Nous avons utilisé des ARN interférant (siRNA) spécifiques pour induire une réduction de l'expression de Gα12/13 ou β-arrestin 1/β-arrestin 2. La conséquence sur l’entrée de Ca2+ dans les cellules a été ensuite déterminée par imagerie calcique en temps réel suite à une stimulation par la vasopressine (AVP), thapsigargin ou carbachol. Nous avons donc identifié que dans des cellules A7r5, une lignée cellulaire de musculaires lisses vasculaires où le canal TRPC6 exprimé de manière endogène, la diminution de l’expression des protéines Gα12 ou Gα13 ne semble pas modifier l’entrée Ca2+ induit par l’AVP par rapport aux cellules témoins. D'autre part, la diminution de l’expression β-arrestin 1 ou β-arrestin 2 dans des cellules HEK 293 ainsi que des cellules HEK 293 exprimant de façon stable TRPC6 (cellules T6.11) ont augmenté l’entrée de Ca2+ induite par thapsigargin, un activateur pharmacologique de SOCE. Des études de co-immunoprécipitation démontrent une interaction entre la β-arrestin 1 et STIM1, alors qu'aucune interaction n'a été observée entre les β-arrestin 1 et Orai1. Nous avons de plus montré à l'aide d'analyse en microscopie confocale que la diminution de l’expression β-arrestin 1 ou β-arrestin 2 n’influence pas la quantité d’Orai1 à la périphérie cellulaire. Cependant, des résultats préliminaires indiquent que la diminution de l’expression β-arrestin 1 ou β-arrestin 2 augmente la quantité de STIM1-YFP dans l'espace intracellulaire et diminue sa quantité à la périphérie cellulaire. En conclusion, nous avons montré que les β-arrestin 1 ou β-arrestin 2 sont impliquées dans l'entrée capacitative de Ca2+ (SOCE) et contrôlent la quantité de STIM1 dans le réticulum endoplasmique. / Abstract : In an organism, intracellular [Ca2+] takes part in many biological processes. Eukaryotic cells express a variety of channels in the plasma membrane through which calcium can enter. In non-excitable cells, two main mechanisms allow calcium entry; the store-operated calcium entry via Orai1 (SOCE) and receptor-operated calcium entry (ROCE). Several key proteins are involved in the regulation of these calcium entry pathways as well as in calcium homeostasis. TRPC6 is a calcium channel implied in calcium entrance into the cells following hormonal stimulation and translocates to the plasma membrane. TRPC6 channel appear to the plasma membrane until the stimulus is present. Although, the mechanisms that regulate the trafficking and activation of TRPC6 are still little known. Recent findings have demonstrated that there is a potential role of Rho kinase in activity of TRPC6. Rho kinase is activated by the small G protein RhoA that itself can be activated by the heterotrimeric G proteins Gα12 and Gα13. In addition to Gα12 and Gα13 proteins, cytosolic GPCR desensitizing proteins β-arrestin 1 and/or β-arrestin 2 could also activate RhoA. The purpose of our study is to investigate the involvement of the proteins Gα12/13 and β-arrestin 1/β-arrestin 2 in the activation of TRPC6 and Orai1 protein. We used siRNA specific to Gα12/13 or β-arrestin 1/β-arrestin 2 to knockdown their endogenous expression. Then, calcium imaging in real time was performed in order to see the quantity of calcium entered into the cell following stimulation by vasopressin (AVP), thapsigargin, or carbachol. We hence identified that in A7r5 cell, vascular smooth muscle cell where TRPC6 channel expressed endogenously; reduced expression of Gα12 or Gα13 proteins does not seem to modify the AVP-induced Ca2+ entry compared to control cells. On the other hand, calcium imaging experiment in knocked down β-arrestin 1 or β-arrestin 2 in HEK 293 cells as well as HEK 293 cells stably transfected with TRPC6 (T6.11 cells) resulted in an increased thapsigargin-induced calcium entry. The co-immunoprecipitation studies demonstrate an interaction between β-arrestin 1 and STIM1, a calcium sensor in SOCE influx, while no interaction was observed between β-arrestin 1 and Orai1.We moreover showed by confocal microscopy that reduced expression of β-arrestin 1/ β-arrestin 2 does not influence the quantity of Orai1 at the cell periphery. Preliminary results showed that reduced expression of β-arrestin 1 or β-arrestin 2 increases the quantity of STIM1-YFP in the intracellular space and less it’s in peri-membrane space. In conclusion, we showed that β-arrestin 1 or β-arrestin 2 are involved in the store-operated calcium entry (SOCE) and control the quantity of STIM1 in the endoplasmic reticulum.

Introdução: A lesão do podócito exerce um papel crítico na nefropatia diabética (ND) e é um fator preditivo de albuminúria patológica e progressão da doença. Neste estudo foi avaliada a expressão gênica de proteínas associadas ao podócito na urina de pacientes diabéticos em diferentes estágios da ND e em indivíduos com pré diabetes. Material e Métodos: Foram estudados 67 pacientes diabéticos com normo (n=34), micro (n=14) ou macroalbuminúria (n=19), dezenove indivíduos pré diabéticos e 15 controles saudáveis. O RNAm de nefrina, podocina, podocalixina, sinaptopodina, Transient Receptor Potential Cation Channel 6 (TRPC6), alfa actinina-4 e TGF1 foi quantificado por PCR em tempo real (2-ΔΔCt) em células do sedimento urinário. A expressão dos genes alvo do podócito foi correlacionada com albuminúria, controle glicêmico e função renal. O desempenho diagnóstico dos genes para albuminúria patológica foi determinado por curva ROC, e o seu efeito independente sobre esse desfecho foi avaliado por análise de regressão de Poisson. Resultados: O RNAm na urina dos genes alvo foi significativamente maior nos pacientes diabéticos em comparação aos não diabéticos, exceto de sinaptopodina e TGFβ1. A expressão de nefrina foi mais elevada nos indivíduos diabéticos micro e macroalbuminúricos comparado aos controles (p=0,04 e p<0,001 respectivamente), pré diabéticos (p<0,05) e normoalbuminúricos (p<0,05). Embora sua expressão tenha sido maior do que nos não diabéticos, os genes TRPC6, podocalixina e alfa actinina-4 não discriminaram os estágios da ND. A correlação da expressão dos genes com albuminúria e hemoglobina glicada foi estatisticamente significativa. Pacientes pré diabéticos tiveram expressão gênica semelhante aos controles. Na análise multivariada, apenas o gene da nefrina foi preditivo de albuminúria patológica. 6 Conclusões: A expressão das proteínas associadas ao podócito na urina foi maior nos pacientes diabéticos, mas não houve correlação direta do RNAm dos genes com níveis crescentes de albuminúria, exceto de nefrina. O gene da nefrina foi o único que discriminou os diferentes estágios da ND e foi preditivo de albuminúria patológica, mas a podocalixina e o TRPC6 também se correlacionaram com albuminúria e controle glicêmico. Neste estudo preliminar não se identificou aumento da expressão gênica das proteínas do podócito na urina em indivíduos com pré diabetes. / Introduction: Podocyte damage plays a critical role in the development of diabetic nephropathy (DN). The present study evaluated gene expression of podocyte-associated proteins in urine of pre-diabetic and diabetic patients at different stages of DN. Material and Methods: We studied 19 pre-diabetic patients, 67 diabetic patients with normo (n = 34), micro (n = 15), or macroalbuminuria (n = 19), and 15 healthy controls. Levels of mRNA of nephrin, podocin, podocalyxin, synaptopodin, transient receptor potential cation channel 6 (TRPC6), alpha-actinin-4, and TGF-1 were quantitatively measured by real-time polymerase chain reaction in urinary sediment. Gene expression was correlated with albuminuria, glycemic control, and renal function. The diagnostic performance of the genes for detecting pathological albuminuria was assessed by the receiver operating characteristic (ROC) curve and Poisson regression. Results: The mRNA expression of target genes in urinary sediment was significantly higher in diabetic compared to pre-diabetic patients and controls. Levels of nephrin were higher in diabetic patients with micro or macroalbuminuria than controls (p= 0.04 and p<0.001, respectively), pre-diabetic (p<0.05), and diabetic patients with normoalbuminuria (p<0.05), and increased with increasing rates of albuminuria. Gene expression was similar in pre-diabetic patients and controls. There was a significant positive correlation of gene expression with albuminuria and glycated hemoglobin. In the multivariate analysis, only nephrinuria predicted pathological albuminuria. Conclusions: The expression of podocyte-associated proteins in urine was higher in diabetic patients, but only nephrin correlated with increasing albuminuria and predicted 8 pathological albuminuria. This preliminary study did not find increased gene transcription in pre-diabetic patients.

Introdução: A lesão do podócito exerce um papel crítico na nefropatia diabética (ND) e é um fator preditivo de albuminúria patológica e progressão da doença. Neste estudo foi avaliada a expressão gênica de proteínas associadas ao podócito na urina de pacientes diabéticos em diferentes estágios da ND e em indivíduos com pré diabetes. Material e Métodos: Foram estudados 67 pacientes diabéticos com normo (n=34), micro (n=14) ou macroalbuminúria (n=19), dezenove indivíduos pré diabéticos e 15 controles saudáveis. O RNAm de nefrina, podocina, podocalixina, sinaptopodina, Transient Receptor Potential Cation Channel 6 (TRPC6), alfa actinina-4 e TGF1 foi quantificado por PCR em tempo real (2-ΔΔCt) em células do sedimento urinário. A expressão dos genes alvo do podócito foi correlacionada com albuminúria, controle glicêmico e função renal. O desempenho diagnóstico dos genes para albuminúria patológica foi determinado por curva ROC, e o seu efeito independente sobre esse desfecho foi avaliado por análise de regressão de Poisson. Resultados: O RNAm na urina dos genes alvo foi significativamente maior nos pacientes diabéticos em comparação aos não diabéticos, exceto de sinaptopodina e TGFβ1. A expressão de nefrina foi mais elevada nos indivíduos diabéticos micro e macroalbuminúricos comparado aos controles (p=0,04 e p<0,001 respectivamente), pré diabéticos (p<0,05) e normoalbuminúricos (p<0,05). Embora sua expressão tenha sido maior do que nos não diabéticos, os genes TRPC6, podocalixina e alfa actinina-4 não discriminaram os estágios da ND. A correlação da expressão dos genes com albuminúria e hemoglobina glicada foi estatisticamente significativa. Pacientes pré diabéticos tiveram expressão gênica semelhante aos controles. Na análise multivariada, apenas o gene da nefrina foi preditivo de albuminúria patológica. 6 Conclusões: A expressão das proteínas associadas ao podócito na urina foi maior nos pacientes diabéticos, mas não houve correlação direta do RNAm dos genes com níveis crescentes de albuminúria, exceto de nefrina. O gene da nefrina foi o único que discriminou os diferentes estágios da ND e foi preditivo de albuminúria patológica, mas a podocalixina e o TRPC6 também se correlacionaram com albuminúria e controle glicêmico. Neste estudo preliminar não se identificou aumento da expressão gênica das proteínas do podócito na urina em indivíduos com pré diabetes. / Introduction: Podocyte damage plays a critical role in the development of diabetic nephropathy (DN). The present study evaluated gene expression of podocyte-associated proteins in urine of pre-diabetic and diabetic patients at different stages of DN. Material and Methods: We studied 19 pre-diabetic patients, 67 diabetic patients with normo (n = 34), micro (n = 15), or macroalbuminuria (n = 19), and 15 healthy controls. Levels of mRNA of nephrin, podocin, podocalyxin, synaptopodin, transient receptor potential cation channel 6 (TRPC6), alpha-actinin-4, and TGF-1 were quantitatively measured by real-time polymerase chain reaction in urinary sediment. Gene expression was correlated with albuminuria, glycemic control, and renal function. The diagnostic performance of the genes for detecting pathological albuminuria was assessed by the receiver operating characteristic (ROC) curve and Poisson regression. Results: The mRNA expression of target genes in urinary sediment was significantly higher in diabetic compared to pre-diabetic patients and controls. Levels of nephrin were higher in diabetic patients with micro or macroalbuminuria than controls (p= 0.04 and p<0.001, respectively), pre-diabetic (p<0.05), and diabetic patients with normoalbuminuria (p<0.05), and increased with increasing rates of albuminuria. Gene expression was similar in pre-diabetic patients and controls. There was a significant positive correlation of gene expression with albuminuria and glycated hemoglobin. In the multivariate analysis, only nephrinuria predicted pathological albuminuria. Conclusions: The expression of podocyte-associated proteins in urine was higher in diabetic patients, but only nephrin correlated with increasing albuminuria and predicted 8 pathological albuminuria. This preliminary study did not find increased gene transcription in pre-diabetic patients.

Introdução: A lesão do podócito exerce um papel crítico na nefropatia diabética (ND) e é um fator preditivo de albuminúria patológica e progressão da doença. Neste estudo foi avaliada a expressão gênica de proteínas associadas ao podócito na urina de pacientes diabéticos em diferentes estágios da ND e em indivíduos com pré diabetes. Material e Métodos: Foram estudados 67 pacientes diabéticos com normo (n=34), micro (n=14) ou macroalbuminúria (n=19), dezenove indivíduos pré diabéticos e 15 controles saudáveis. O RNAm de nefrina, podocina, podocalixina, sinaptopodina, Transient Receptor Potential Cation Channel 6 (TRPC6), alfa actinina-4 e TGF1 foi quantificado por PCR em tempo real (2-ΔΔCt) em células do sedimento urinário. A expressão dos genes alvo do podócito foi correlacionada com albuminúria, controle glicêmico e função renal. O desempenho diagnóstico dos genes para albuminúria patológica foi determinado por curva ROC, e o seu efeito independente sobre esse desfecho foi avaliado por análise de regressão de Poisson. Resultados: O RNAm na urina dos genes alvo foi significativamente maior nos pacientes diabéticos em comparação aos não diabéticos, exceto de sinaptopodina e TGFβ1. A expressão de nefrina foi mais elevada nos indivíduos diabéticos micro e macroalbuminúricos comparado aos controles (p=0,04 e p<0,001 respectivamente), pré diabéticos (p<0,05) e normoalbuminúricos (p<0,05). Embora sua expressão tenha sido maior do que nos não diabéticos, os genes TRPC6, podocalixina e alfa actinina-4 não discriminaram os estágios da ND. A correlação da expressão dos genes com albuminúria e hemoglobina glicada foi estatisticamente significativa. Pacientes pré diabéticos tiveram expressão gênica semelhante aos controles. Na análise multivariada, apenas o gene da nefrina foi preditivo de albuminúria patológica. 6 Conclusões: A expressão das proteínas associadas ao podócito na urina foi maior nos pacientes diabéticos, mas não houve correlação direta do RNAm dos genes com níveis crescentes de albuminúria, exceto de nefrina. O gene da nefrina foi o único que discriminou os diferentes estágios da ND e foi preditivo de albuminúria patológica, mas a podocalixina e o TRPC6 também se correlacionaram com albuminúria e controle glicêmico. Neste estudo preliminar não se identificou aumento da expressão gênica das proteínas do podócito na urina em indivíduos com pré diabetes. / Introduction: Podocyte damage plays a critical role in the development of diabetic nephropathy (DN). The present study evaluated gene expression of podocyte-associated proteins in urine of pre-diabetic and diabetic patients at different stages of DN. Material and Methods: We studied 19 pre-diabetic patients, 67 diabetic patients with normo (n = 34), micro (n = 15), or macroalbuminuria (n = 19), and 15 healthy controls. Levels of mRNA of nephrin, podocin, podocalyxin, synaptopodin, transient receptor potential cation channel 6 (TRPC6), alpha-actinin-4, and TGF-1 were quantitatively measured by real-time polymerase chain reaction in urinary sediment. Gene expression was correlated with albuminuria, glycemic control, and renal function. The diagnostic performance of the genes for detecting pathological albuminuria was assessed by the receiver operating characteristic (ROC) curve and Poisson regression. Results: The mRNA expression of target genes in urinary sediment was significantly higher in diabetic compared to pre-diabetic patients and controls. Levels of nephrin were higher in diabetic patients with micro or macroalbuminuria than controls (p= 0.04 and p<0.001, respectively), pre-diabetic (p<0.05), and diabetic patients with normoalbuminuria (p<0.05), and increased with increasing rates of albuminuria. Gene expression was similar in pre-diabetic patients and controls. There was a significant positive correlation of gene expression with albuminuria and glycated hemoglobin. In the multivariate analysis, only nephrinuria predicted pathological albuminuria. Conclusions: The expression of podocyte-associated proteins in urine was higher in diabetic patients, but only nephrin correlated with increasing albuminuria and predicted 8 pathological albuminuria. This preliminary study did not find increased gene transcription in pre-diabetic patients.

Der unselektive Kationenkanal TRPC6 (transient receptor potential canonical 6) wird durch den second messenger Diacylglycerol (DAG) aktiviert und spielt eine wichtige Rolle bei einer Vielzahl physiologischer und pathophysiologischer Prozesse. Um neuartige Therapien zu ermöglichen, ist die Identifizierung potenter und selektiver Kanalmodulatoren von großem Interesse. Die vorliegende Dissertation widmet sich der Identifizierung, Optimierung und Charakterisierung neuer Inhibitoren sowie Aktivatoren des TRPC6-Ionenkanals. Im ersten Teil der Arbeit werden aufbauend auf früheren Studien diverse Modifikationen am Grundgerüst des TRPC6-selektiven terpenoiden Naturstoffs (+)-Larixol vorgenommen, um eine umfassende Struktur-Wirkungsbeziehung zu erstellen. Die Derivate werden durch fluorometrische Ca2+-Influx-Analysen sowie elektrophysiologische patch clamp-Untersuchungen in HEK293-Zellen mit stabiler Überexpression der Kanäle TRPC6, TRPC3 und TRPC7 charakterisiert. Die potenteste Verbindung Larixyl-N-methylcarbamat Lab-19 weist eine 16-fach höhere TRPC6-Affinität als die Leitstruktur (+)-Larixol und 4-fache bzw. 13-fache Selektivität gegenüber den nah verwandten Ionenkanälen TRPC7 und TRPC3 auf. Die Inhibition von nativ exprimierten TRPC6-Kanalkomplexen wird durch die Anwendung von Lab-19 in pulmonalen glatten Gefäßmuskelzellen der Ratte demonstriert. Weiterhin führt die Behandlung von isolierten, perfundierten Mauslungen mit Lab-19 zu einer Reduktion des Ischämie-Reperfusionsödems, einer lebensbedrohlichen Komplikation bei Lungentransplantationen. Der zweite Teil beschreibt das Screening einer 16.671 Substanzen umfassenden Wirkstoffbibliothek nach potentiellen Kanalaktivatoren und deren Charakterisierung. Die Beschreibung und Synthese der vielversprechendsten Verbindung C20 aus dieser Studie erfolgt in einem dritten Teil der Arbeit. C20 wirkt selektiv auf TRPC6, was die Substanz von bisherigen Aktivatoren wie OAG (1-Oleoyl-2-acetyl-sn-glycerol) unterscheidet, welche auch die Ionenkanäle TRPC3 und TRPC7 aktivieren. Eingehende Untersuchungen mithilfe von Ca2+-Assays und elektrophysiologischen Experimenten zeigen, dass C20 als positiv allosterischer Modulator agiert und eine Kanalaktivierung verstärkt. Die Verbindung C20 wird schließlich in humanen Thrombozyten getestet, für welche eine Expression von TRPC6 beschrieben ist. Die Kombination von OAG und C20 führt zu einem signifikant höheren Anstieg des intrazellulären Calciums in Thrombozyten verglichen mit einer gewöhnlichen Antwort auf OAG-induzierte Aktivierung. Diese Beobachtungen unterstreichen die Eignung des identifizierten positiven Modulators C20 als zukünftiges selektives Demaskierungswerkzeug für TRPC6-Signale in nativen Geweben.:Inhaltsverzeichnis Abbildungsverzeichnis III Schemataverzeichnis IV Tabellenverzeichnis V Abkürzungen VI 1 EINLEITUNG 1 1.1 DIE FAMILIE DER TRP-IONENKANÄLE 2 1.2 DER TRPC6-KATIONENKANAL 7 1.2.1 Struktur und Regulation 7 1.2.2 Physiologische Relevanz 8 1.3 MODULATOREN DES TRPC6-IONENKANALS 9 1.3.1 Aktivatoren 11 1.3.2 Inhibitoren 14 1.3.3 TRPC6-Inhibition durch Larixolderivate 16 2 ZIELSTELLUNG 19 3 EXPERIMENTELLER TEIL 21 3.1 CHEMISCHE SYNTHESEN 21 3.1.1 Reagenzien und Lösungsmittel 21 3.1.2 Analytische Methoden 21 3.1.3 Synthesen 23 3.2 BIOLOGISCHE METHODEN 43 3.2.1 Reagenzien, Lösungsmittel und Puffer 43 3.2.2 Aktivatoren, Inhibitoren, Pharmaka 44 3.2.3 Verbrauchsmaterialien 44 3.2.4 Zellkultur 45 3.2.5 Transiente Transfektion 45 3.2.6 Bestimmung der Zellviabilität 46 3.2.7 Fluoreszenz-Imaging 47 3.2.8 Elektrophysiologie 51 3.2.9 Analyse des Ischämie-Reperfusions-Ödem in isolierten Mauslungen 53 3.2.10 Isolierung humaner Thrombozyten 54 3.2.11 Aggregometrie 54 3.2.12 Datenanalyse 53 4 ERGEBNISSE 55 4.1 SAR-STUDIE NATURSTOFFBASIERTER TRPC6-KANAL-INHIBITOREN 55 4.1.1 Isolierung des Naturstoffes Larixol aus dem Lärchenharz 55 4.1.2 Erstellung einer labdanbasierten Substanzbibliothek 56 4.1.3 SAR-Daten der Inhibition von TRPC3, TRPC6 und TRPC6 60 4.1.4 Auswirkung der Larixolderivate auf die Zellviabilität 69 4.1.5 Subtypspezifität von Larixylmethylcarbamat 69 4.1.6 Elektrophysiologische Charakterisierung der TRPC3/6/7-Inhibition durch Lab-19 73 4.1.7 Wirkung von Larixylmethylcarbamat auf Zellen mit endogener TRPC6-Expression 75 4.1.8 Diskussion 76 4.2 IDENTIFIZIERUNG POSITIVER TRPC6-IONENKANALMODULATOREN 82 4.2.1 Hochdurchsatz-Screening der ChemBioNet-Bibliothek 82 4.2.2 Funktionelle Charakterisierung von 46-J17 88 4.2.3 Diskussion 90 4.3 CHARAKTERISIERUNG DES POSITIVEN ALLOSTERISCHEN TRPC6-MODULATORS 93 4.3.1 C20 induziert transienten Ca2+-Einstrom in HEKhTRPC6-YFP-Zellen 93 4.3.2 C20 – ein positiver TRPC6-Modulator 97 4.3.3 Untersuchung mechanistischer Aspekte der TRPC6-Potenzierung 100 4.3.4 Aktivierung des TRPC6 im physiologischen System 103 4.3.5 Diskussion 106 5 ZUSAMMENFASSUNG UND AUSBLICK 111 6 LITERATUR 115 Appendix

Metabolic syndrome is a significant worldwide public health challenge and is inextricably linked to adverse renal and cardiovascular outcomes. The inhibition of the transient receptor potential cation channel subfamily C member 6 (TRPC6) has been found to ameliorate renal outcomes in the unilateral ureteral obstruction (UUO) of accelerated renal fibrosis. Therefore, the pharmacological inhibition of TPRC6 could be a promising therapeutic intervention in the progressive tubulo-interstitial fibrosis in hypertension and metabolic syndrome. In the present study, we hypothesized that the novel selective TRPC6 inhibitor SH045 (larixyl N-methylcarbamate) ameliorates UUO-accelerated renal fibrosis in a New Zealand obese (NZO) mouse model, which is a polygenic model of metabolic syndrome. The in vivo inhibition of TRPC6 by SH045 markedly decreased the mRNA expression of pro-fibrotic markers (Col1a1, Col3a1, Col4a1, Acta2, Ccn2, Fn1) and chemokines (Cxcl1, Ccl5, Ccr2) in UUO kidneys of NZO mice compared to kidneys of vehicle-treated animals. Renal expressions of intercellular adhesion molecule 1 (ICAM-1) and -smooth muscle actin (-SMA) were diminished in SH045- versus vehicle-treated UUO mice. Furthermore, renal inflammatory cell infiltration (F4/80+ and CD4+) and tubulointerstitial fibrosis (Sirius red and fibronectin staining) were ameliorated in SH045-treated NZO mice. We conclude that the pharmacological inhibition of TRPC6 might be a promising antifibrotic therapeutic method to treat progressive tubulo-interstitial fibrosis in hypertension and metabolic syndrome.

Les canaux TRP (Transient Receptor Potential) sont des acteurs clés de l'homéostasie calcique. Plusieurs de ces canaux interviennent dans l'influx calcique des cellules épithéliales bronchiques, notamment TRPC6, qui est impliqué dans un couplage fonctionnel avec le canal Cystic Fibrosis Transmembrane conductance Regulator (CFTR). Les mutations du CFTR (F508del et G551D) sont à l'origine de la mucoviscidose (Cystic Fibrosis (CF)), qui aboutit à l'augmentation de l'influx calcique dans les cellules CF. L'objectif de ce travail a été d'étudier l'implication des canaux TRP dans la dérégulation de l'influx calcique des cellules épithéliales bronchiques CF. Nous avons mis en évidence que CFTR régulait négativement l'activité de TRPC6, tandis que l'influx calcique via TRPC6 permettait de potentialiser l'activité du canal muté CFTR-G551D, activé au préalable par le VX-770. Nous proposons donc une nouvelle stratégie thérapeutique, combinant un potentiateur de CFTR et un activateur spécifique de TRPC6. Nous nous sommes ensuite intéressés au rôle des canaux TRPV, en particulier TRPV5 et TRPV6, dans l'influx calcique des cellules épithéliales bronchiques. Nous avons observé que l'influx Ca2+ constitutif, attribuable à ces deux canaux, était doublé dans les cellules CF, dû à une augmentation de l'activité de TRPV6. En effet, l'expression de la PLC-δ1, une enzyme régulant négativement TRPV6, est dramatiquement réduite dans les cellules CF. La correction de l'adressage du F508del-CFTR a permis de normaliser l'activité de TRPV6 sans restaurer l'expression de la PLC-δ1 dans les cellules CF, suggérant un contrôle plus complexe de TRPV6 dans les cellules épithéliales bronchiques. / TRP (Transient Receptor Potential) channels are keys actors of Ca2+ homeostasis. Several of these channels are involved in the Ca2+ influx of bronchial epithelial cells, including TRPC6 which is implicated in a functional coupling with the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) channel. CFTR mutation leads Cystic Fibrosis (CF) disease and causes abnormal Ca2+ homeostasis trought an increased of Ca2+ influx in CF bronchial epithelial cells. Our objective is to investigate the implication of TRP channels in abnormal Ca2+ influx of CF bronchial epithelial cells.We showed that CFTR down regulates TRPC6 activity whereas Ca2+ influx through TRPC6 potentiates G551D-CFTR, activated by VX-770. We propose a new therapeutic strategy that combines a CFTR potentiator and a specific activator of TRPC6. Then, we focused on the role of TRPV channels, particularly TRPV5 and TRPV6, in Ca2+ influx of bronchial epithelial cells. We observed that constitutive Ca2+ influx, related to TRPV5/TRPV6 activity, was twice higher in CF cells due to the increase of TRPV6 activity. The expression of PLC-δ1, an enzyme that negatively regulates TRPV6 activity, is dramatically decreased in CF cells. The correction of F508del-CFTR trafficking allows TRPV6 activity normalization but do not restore PLC-δ1 expression level in CF cells, suggesting a more complex control of TRPV6 in bronchial epithelial cells.

Focal segmental glomerulosclerosis is one of the commonest cause of the nephrotic syndrome in adults patients. It is a damage of glomerulus characterized by leakage of proteins to urine and oedemas which usually develops into the end-stage renal disease within 10 years. Recently have been described familial forms of this disease which arise from injury to proteins making up filtration barrier of kidney. In 2005 non-selective ion channel TRPC6 was assigned among these proteins. In this thesis I focused on summarizing existing knowledge of the nephrotic syndrome, focal segmental glomerulosclerosis and involvement of TRPC6 in their origin. Second part of this work is devoted to the screening analysis of TRPC6 gene to discover possible mutations and polymorfisms in 47 patients with histologically proven focal segmental glomerulosclerosis or minimal change disease. The used methods were high resolution melting and direct sequencing. In the group of patients was detected no pathogenic mutation, only 2 known polymorfisms P15S and A404V and few changes which do not result in alteration of amino acid. So it seems TRPC6 gene mutations are a rare cause of the focal segmental glomerulosclerosis in adult patients in the Czech Republic.

TRPC6 (transient receptor potential cation channels; canonical subfamily C, member 6) is widespread localized in mammalian tissues like kidney and lung and associated with progressive proteinuria and pathophysiological pulmonary alterations, e.g., reperfusion edema or lung fibrosis. However, the understanding of TRPC6 channelopathies is still at the beginning stages. Recently, by chemical diversification of (+)-larixol originating from Larix decidua resin traditionally used for inhalation, its methylcarbamate congener, named SH045, was obtained and identified in functional assays as a highly potent, subtype-selective inhibitor of TRPC6. To pave the way for use of SH045 in animal disease models, this study aimed at developing a capable bioanalytical method and to provide exploratory pharmacokinetic data for this promising derivative. According to international guidelines, a robust and selective LC-MS/MS method based on MRM detection in positive ion mode was established and validated for quantification of SH045 in mice plasma, whereby linearity and accuracy were demonstrated for the range of 2–1600 ng/mL. Applying this method, the plasma concentration time course of SH045 following single intraperitoneal administration (20 mg/kg body weight) revealed a short half-life of 1.3 h. However, the pharmacological profile of SH045 is promising, as five hours after administration, plasma levels still remained sufficiently higher than published low nanomolar IC50 values. Summarizing, the LC-MS/MS method and exploratory pharmacokinetic data provide essential prerequisites for experimental pharmacological TRPC6 modulation and translational treatment of TRPC6 channelopathies.

Les canaux TRPC6 sont des canaux cationiques non sélectifs qui peuvent être activés par le diacylglycérol (DAG). Ils sont présents dans de nombreux tissus et types cellulaires, notamment dans le cortex de souris embryonnaire (à E13). Des expériences d'imagerie calcique réalisées sur des neurones de cortex de souris en culture ont révélé la présence de canaux cationiques activés par le DAG. Ils sont perméables aux ions Ca2+, Na+, Ba2+ et Mn2+. L'entrée de Ca2+ via ces canaux est indépendante de la protéine kinase C et elle est bloquée par le SKF-96365 et le Gd3+. Par ailleurs, l'acide flufénamique augmente l'amplitude des réponses calciques induites par le DAG. Des expériences d'électrophysiologie réalisées avec la technique du patch-clamp en configuration cellule entière ont montré que l'hyperforine, un activateur des canaux TRPC6, donne naissance à un courant cationique non sélectif, confirmant ainsi l'existence de canaux de type TRPC6 dans les neurones corticaux. Des analyses quantitatives en spectrométrie d'émission atomique à plasma couplé inductif, en spectrométrie d'absorption atomique et en fluorescence X avec la nanosonde synchrotron (µ-SXRF) révèlent que la surexpression de TRPC6 dans les cellules HEK-293 s'accompagne d'une augmentation du contenu intracellulaire en zinc, en soufre et en manganèse. Les résultats obtenus avec des sondes fluorescentes sensibles au zinc et au fer indiquent que les canaux TRPC6 peuvent transporter ces cations. Par ailleurs, les expériences en µ-SXRF montrent que l'activation des canaux TRPC6 en présence de fer induit une accumulation de ce métal dans les cellules HEK et les neurones. Au cours de notre étude, nous avons également mis en évidence l'action de deux agents (l'acide flufénamique et l'hyperforine), couramment utilisés pour modifier l'activité des canaux TRPC6, sur la physiologie mitochondriale et l'homéostasie des métaux. En effet, l'acide flufénamique et l'hyperforine non seulement modifient le fonctionnement des canaux TRPC6 mais ils exercent aussi une action de type découplante sur les mitochondries, provoquant une libération de Ca2+ et de Zn2+ à partir de ces organelles.