How does cellular volume regulation works: Contribution of anoctamins, LRRC8A and CFTR

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1 S Februar 2017 Current projects How does cellular volume regulation works: Contribution of anoctamins, LRRC8A and CFTR Recent results from our lab indicate a central role of anoctamins such as ANO1, ANO6 and CFTR for cellular volume regulation and regulated cell death, apart from the LRRC8A (VRAC) family. We currently examine fibrosis (in collaboration with Prof. Dr. Margarida Amaral, University of Lisboa, Portugal) the interesting relationship between these ion channels.

2 _ Control of intracellular Ca 2+ signaling Anoctamins may couple differentially to proteins essential for intracellular Ca 2+ signalling. We examine anoctamin-dependent Ca 2+ signalling in the primary cilium and in the plasma membrane. _ Roles of anoctamin 1 and 6 for airway Cl - secretion and support of Cl - secretion by CFTR Luminal Colon Basolateral Luminal Airways Basolateral Ano1 CFTR Golgi ER Ano1 ATP Cl - Cl - P2Y IP 3 Ano1 PDZ CFTR IP 3 R Ca 2+ camp ORAI ER SOcAMPS sacs Anoctamins in intestinal and airway epithelial cells may induce Ca 2+ dependent Cl - secretion directly by operating as an apical exit pathway for Cl -, or indirectly by supporting Ca 2+ dependent activation of CFTR or basolateral K + channels. We examine the molecular and functional interaction of CFTR and anoctamins.

3 Role of anoctamins for mucus production and secretion Mucus is the biggest problem in cystic fibrosis/mucoviscidosis (left). We examine the role of ANO1 for mucus synthesis and secretion by goblet and club cells (right). Role of anoctamins in renal tubules and polycystic kidney disease Anoctamin 1 is expressed in renal proximal tubular epithelial cells were it controls H + secretion by the V-ATPase and protein absorption (left). Cyst formation in a renal cyst model is largely reduced in the presence of the ANO1 inhibitor CaCCinhAO1 (AO1; right). Also CFTR is expressed in proximal tubule and collecting duct cells. We examine in collaboration with Dr. Björn Buchholz (University hospital Erlangen) how CFTR and anoctamins control cyst development and growth.

4 Role of anoctamins during inflammation Anoctamin 6 and 1 are activated by reactive oxygen species (ROS), which might play a central role during inflammation and regulated cell death. We examine this regulation in the context of cystic fibrosis (in collaboration with Prof. Dr. Margarida Amaral, University of Lisboa, Portugal) and in relation to polycystic kidney disease (in collaboration with Dr. Björn Buchholz, University hospital Erlangen) Roles of anoctamins for regulated cell death (apoptosis, necroptosis Anoctamin 6 is activated during apoptotic cell death and might also be relevant for cell death by programmed necrosis (necroptosis) and other forms of regulated cell death, such as pyroptosis. We examine in collaboration with other teams (PD Dr. med. Andreas Linkermann, Universitätsklinikum Carl Gustav Carus, Dresden; Prof. Dr. rer. nat. Stefan Krautwald, Universitätsklinikum Schleswig-Holstein Campus Kiel

5 Role of anoctamins in the primary cilium Anoctamin 6 is located in the primary (central) cilium of polarized grown renal epithelial cells and might probably have a role in signal transduction. We examine in collaboration with Dr. Björn Buchholz (University hospital Erlangen) the function of anoctamins in the primary cilium and how they may control cyst development and growth Role of anoctamins for leucocyte NETtosis Leukocytes release their nuclear chromatin (left) to form an extracellular network that traps bacteria and other microorganisms (right). Anoctamins could contribute to the initial cell shrinkage required for NETtosis. For this project we will use immune cells from knockout animals.

6 Identification of novel proteins and small molecule compounds to regulate anoctamin 1 and 6 A double tagged (extracellular, intracellular) anoctamin will be stably expressed and used to screen in an automatic microscopy-based high throughout method for i) novel target proteins controlling biosynthesis and activity of anoctamins, and ii) to identify novel small molecules as modulators of biosynthesis and activity of anoctamins. Targets will be validated. (In collaboration with Prof. Dr. Margarida Amaral, University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Lisboa, Portugal) Role of CFTR for renal HCO3 - secretion and salt absorption CFTR is expressed in the proximal tubule and the intercalated type-b cells of the collecting duct. In collaboration with Prof. Dr. Jens Leipziger, University of Aarhus, Denmark, and Prof. em. Dr. Hans Beat Hadorn we examine whether CFTR regulates renal HCO3 - secretion and Na + absorption by controlling NHE3 and SLC26A4 (pendrin).