Channelopathies induce severe heart rhythm or conduction disorders. Mutations of the KCNH2 gene, that encodes the human (h) ERG channel, is responsible for 30% of all cases of long QT syndrome. Besides, hERG is frequently responsible for off-target effects of several pharmacological agents. With the advent of Next Generation Sequencing, hundreds of new KCNH2 variants are accumulating in various databases, many being of unknown significance to clinicians which hampers the value of their diagnosis and the quality of patient management. Therefore, there is an urgent need to functionally characterize a large fraction of KCNH2 variants and provide access of this information to hospital clinicians. We assembled a consortium of clinicians, geneticists, biophysicists and computer bioscientists to build the largest web-accessible diagnostic/prognostic database of hERG-related channelopathies. To this end, we will take advantage of high-throughput techniques of channel variant phenotyping.

The function of a channel in a neuron relies on the synergistic activity of several different ion channels in the system during physiological activity, as these determine the membrane potential and the intracellular calcium. Yet, the interplay of the diverse channels underlying a physiological signal is unknown and this information can be extracted only by quantitative analysis of a rich experimental dataset taking into account the role of each individual channel. This project aims at developing novel technologies to address the challenge of investigating multiple activations of different ion channels in native systems, which should lead to a better understanding of how mutations of a channel translate into global pathological signals. To achieve this goal, we propose to develop several photoactivable toxins (TASK 1) and an original software based on NEURON (TASK 2) to be used for analyses of data generated with our cutting-edge optical techniques, permitting the reconstruction of all ionic currents involved in a physiological signal. The successful photoactivable toxins will be protected by IP and industrialized contacts, such as Smartox Biotechnology (https://www.smartox-biotech.com/) may be interested for commercialization under a licence agreement. We will initially develop at least six functional photoactivable toxins selective for some of the most relevant neuronal channels and, at a second stage, other toxins according to the evolution of the project. All toxins will be first assessed in terms of photochemical properties, in vitro efficacy for light-induced current blockage, and later for application in brain slices exploiting our expertise in caged compound characterisation. The NEURON-based software will be developed in collaboration (not funded by the ANR) with the ERC-laureate team of Panayiota Poirazi (http://www.dendrites.gr/). We will first produce detailed membrane potential and Ca2+ optical recordings at high temporal resolution using cutting-edge technologies developed in previous ANR projects, dissecting single channel contributions using toxins. Then, we will produce models of neuronal compartments with realistic channels matching the complexity of experimental scenarios and these models will be deposited in the ModelDB database (https://senselab.med.yale.edu/ModelDB/). These tasks will lead to a unique strategy for the analysis of signal dysfunction in animal models of channelopathies (TASK 3). We will deliver an original method to tackle the pivotal question in the study of channelopathies: how the dysfunction of a particular channel can change the function of the other channels to eventually translate in the distortion of a signal underlying brain disorder. The project will be coordinated by the team of Marco Canepari (http://marco-canepari.wix.com/neuron-imaging-team), exploiting his expertise in functional imaging applied to ion channels research in neuroscience. The task of photoactivable toxins development will be devoted to the team of Michel De Waard (http://www.umr1087.univ-nantes.fr/nos-equipes/equipe-iib-insuffisance-cardiaque-et-approches-pharmacologiques-1518040.kjsp?RH=1331825361673) who is leader in cell penetrating peptides for biotechnological applications and in animal toxins, but also the founder of Smartox Biotechnology. Both teams belong to the French LABEX Ion Channels, Science and Therapeutics (ICST, http://www.labex-icst.fr/en) and other teams of the consortium will benefit of this novel strategy in projects investigating channelopathies of the nervous system. We also aim at using this project as kick off for a larger research European program to merge the excellence of French laboratories in experimental technologies to investigate ion channels with the expertise of European teams in computational neuroscience. The longer term goal is to generate a database of native kinetics models of ion channels to explore the channel dysfunctions underlying brain diseases.

Intracranial aneurysms (IAs) affect 3% of the population and IA rupture is a devastating event (40% mortality). The ICAN biobank includes 3400 IA patients with clinical, imaging and DNA. WECAN relies on this exceptional resources for rupture risk stratification among IAs. WP1 uses image processing tools for automatic and morphological characterization of the brain vessels. This will allow an objective characterization of IA. WP2 exploits the whole ICAN population by sequencing a panel of susceptibility genes and genotyping SNPs.WP3 crosses multimodal data to build a predictive model of IA sub-phenotypes and stratify the risk of IA rupture. Quantitative traits extracted from imaging will be cross-analyzed through advanced deep learning strategies with the clinical and genetics data. This strategy has never been performed to date for IAs. The IA pathology will benefit from personalized, precision medicine and FAIR big data analysis, leveraging open science best practices.

The ubiquitin-proteasome system (UPS) is one of the major eukaryotic pathways for intracellular degradation of proteins which are misfolded, oxidized, damaged and/or no longer needed. Denatured proteins to be degraded are specifically tagged with ubiquitin chains before being addressed to the 26S proteasome that ensure their hydrolysis. The UPS is essential to neuronal development and function and most of the approximately 1,200 genes which contribute to this protein degradation pathway are highly expressed in brain. Their pathogenic variants are responsible for about 10-15% of neurodevelopmental disorders (NDDs). Yet, since the recognition of UPS-related NDDs (UPS-NDDs) is fairly recent, virtually nothing is known about how UPS genetic variants can lead to abnormal brain development. The UPS-NDDecipher project was designed to address this question. Its objective is to decipher the physiopathological mechanism of six UPS-NDDs caused by pathogenic genetic variants in USP7, CUL4B, PSMD12, PSMC3, PSMC5 or BAP1. The transdisciplinary approach followed in the project will combine state-of-the-art methods in cell reprogramming and differentiation, neuroimaging and functional genomics applied to patient cells. The implementation of the project is made possible by the contact network with clinical geneticists, scientists and patient organizations that was previously established by members of the UPS-NDDecipher consortium and allowed the initiation of a biocollection dedicated to UPS-NDDs. The occurrence of morphological abnormalities will be monitored during differentiation of patient induced pluripotent stem cells (hiPSC)-derived glutamatergic neurons and culture of mouse hippocampal cell lines. In addition, a specific molecular signature of UPS-NDDS will be sought by comparative integrative multi-omics analysis of patient and isogenic hiPSC-derived neuronal lines. Once a molecular signature specific to the six UPS-NDDs has been identified, selected active compounds will be tested for their ability to restore a normal UPS protein degradation in mutant cells. The ultimate goal of the project is thus to open the way to pre-clinical studies and hopefully to offer therapeutic perspectives to patients.

Despite major progress in the treatment against atherosclerotic cardiovascular disease (ASCVD), new therapeutic alternatives are needed for patients at very high ASCVD risk and/or with side effects upon available therapies. Recently, the inhibition of the G protein-coupled receptor 146 (GPR146), a family of proteins widely used in pharmaceutical targeting, was shown to be protective against hypercholesterolemia and atherosclerosis in mice. The present project aims at : i) Evaluating the druggability-potential of GPR146-inhibition in human. We will systematically look for genetic variations in GPR146 in population cohorts and familial cases of hyper- and hypocholesterolemia and assess their cardiometabolic consequences. ii) Identifying the phenotypic consequences of Gpr146 inhibition in several mouse models with cardiometabolic disorders (dyslipidemia, diabetes, NASH). iii) Refining the GPR146-natural ligand(s) and intracellular signaling pathways in hepatocytes-like cells.