Regulation and modulation of the NALCN channelosome

The sodium leak channel (NALCN) is the ion-channel subunit of the NALCN channelosome, additionally containing UNC79, UNC80 and Fam155. NALCN controls the resting membrane potential (RMP) in excitable tissue (e.g. brain and myometrium) by an inward current of positively charged (sodium) ions that depolarizes the cell membrane, sensitizing the cell to excite (activate). NALCN is essential for survival. Mutations in the NALCN channelosome cause loss- or gain of function of NALCN currents which result in severe developmental disorders IHPRF and CLIFAHDD. Yet, NALCN channelosome physiology is largely unknown and no selective or specific drug-like compounds targeting the NALCN channelosome exist.I propose the objectives: I) to characterize regulation of the NALCN channelosome by endogenous protein partner interactions (PPIs), and II) to identify and characterize de novo designer proteins that modulate NALCN function. I anticipate that this can inform on NALCN physiology and future therapeutic strategies to counteract NALCN loss- or gain of function and other excitability-related disorders.I will perform the research at Copenhagen University in the lab of Professor Stephan Pless, an expert in the field. Objective I-II build onto novel in silico approaches where the Pless lab has identified PPIs based on protein co-evolution, tissue-co-expression, and disease association; and generated de novo designer proteins designed to bind the NALCN channelosome. I will elucidate the objectives experimentally by utilizing – and expanding – my experience in ion-channel research. In Objective I, I will use i) electrophysiology to study the functional impact of PPIs, ii) immunocytochemistry to interrogate sub-cellular localization and trafficking, and iii) biochemistry to determine direct interactions. In Objective II, I will perform electrophysiology on NALCN channelosome-expressing HEK cells and iPSC-derived neurons to find de novo designer proteins that inhibit or potentiate NALCN.