Regulation of calcium concentration in microdomains and primary cilium by TMEM16 proteins and role of TMEM16 and CFTR for renal cystogenesis

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The regulation of the intracellular calcium concentration plays a central role in autosomal dominant polycystic kidney disease (ADPKD) and is potential in other cystic diseases. During the progression of ADPKD the formation of cysts is dependent on calcium activated TMEM16 chloride ion channels. Microdomains as well as the primary cilium are essential structures for local calcium signaling. Our preliminary studies show, that TMEM16 channels modulate the calcium concentration in microdomains. Our project will investigate the impact of TMEM16A and TMEM16F on compartmentalized calcium signaling in vivo and in vitro. For this purpose we will use a kidney specific polycystin1 (PC1) knockout (KO) and TMEM16A and TMEM16F double KO models. The role of TMEM16A and TMEM16B for the cellular calcium signaling and cyst development will be investigated. It is proposed, that in addition to the TMEM16 channels function, activation of CFTR (cystic fibrosis transmembrane conductance regulator) is necessary for cyst development. Because of recently found functional interactions of TMEM16 with CFTR in vivo, kidney specific CFTR KO mice will be investigated, too. Additionally, the impact of TMEM16 on the calcium signaling in the primary cilium will be analyzed in vitro using a cilium specific calcium sensor. As TMEM16 is related to the hedgehog-signaling pathway, the contribution of TMEM16 to this pathway in the primary cilium will be investigated, too. Furthermore, the relevance of the primary cilium, TMEM16 and CFTR for the development of cysts will be investigated in collecting duct organoids. The results of the project will clarify the role of TMEM16 and CFTR for the development of cysts. From the expected findings new potential treatments for cyst diseases could be developed.