PROTEIN AGGREGATION: IMPLEMENTING NEW BIOMEDICAL, STRUCTURAL AND NANOTECHNOLOGICAL STRATEGIES

PROTEIN AGGREGATION IS INTIMATELY LINKED TO THE ETIOLOGY OF NEURODEGENERATIVE DISORDERS. DISEASE-MODIFYING THERAPEUTICS ARE URGENTLY NEEDED FOR THESE FATAL CONDITIONS. A FIRST AIM OF THE PROJECT IS TO ADVANCE IN THE DEVELOPMENT OF TREATMENTS FOR PARKINSON'S DISEASE (PD) AND THE TAUOPATHIES. THE LOSS OF DOPAMINERGIC (DA) NEURONS IN THE BRAINS OF PD PATIENTS IMPAIRS BOTH MOTOR AND COGNITIVE FUNCTIONS. STRONG EVIDENCE CONNECTS THE AGGREGATION OF THE PROTEIN A-SYNUCLEIN (ASYN) AND THE DEATH OF DA NEURONS. OLIGOMERS ARE CONSIDERED RESPONSIBLE FOR THE GAIN-OF-TOXIC FUNCTION ASSOCIATED WITH ASYN AGGREGATION AND, THEREFORE, OFFER PROMISING TARGETS FOR THERAPEUTICS. HOWEVER, ASYN OLIGOMERS HAVE BEEN CONSIDERED ESSENTIALLY UNDRUGGABLE DUE TO THEIR DYNAMIC AND TRANSIENT NATURE. IN A RECENT COLLABORATIVE EFFORT, WE HAVE DETERMINED THE ARCHITECTURE OF ASYN OLIGOMERS, UNCOVERING A REGION RESPONSIBLE FOR THEIR HARMFUL PROPERTIES. THIS ALLOWS TARGETING THESE PATHOGENIC SPECIES SPECIFICALLY WITHOUT IMPACTING THE FUNCTIONAL SYNAPTIC PROTEIN. WE WILL EXPLOIT TWO COMPLEMENTARY STRATEGIES, NAMELY, HUMAN HELICAL PEPTIDES AND NANOBODIES, TO BLOCK ASYN OLIGOMERS AND THEIR NEUROTOXIC EFFECTS. THE MICROTUBULE-ASSOCIATED PROTEIN TAU IS A SCAFFOLDING PROTEIN ENRICHED AT THE NEURONAL AXONS. LIKE IN THE CASE OF ASYN, TAU AGGREGATION IS ASSOCIATED WITH NEURODEGENERATION. TAU IS CONNECTED TO ALZHEIMER'S DISEASE (AD) AS WELL AS TO TAUOPATHIES, A GROUP OF DISORDERS WHERE THE PROTEIN FORMS NEURONAL AND/OR GLIAL INCLUSIONS. AS A RESULT OF A RECENT HIGH-THROUGHPUT SCREENING CAMPAIGN, WE HAVE IDENTIFIED A HIGHLY POTENT SMALL MOLECULE ABLE TO HALT TAU AGGREGATION. WE WILL USE IT AS A SCAFFOLD IN A DRUG-REPURPOSING PIPELINE TO IDENTIFY APPROVED, SAFE AND BRAIN-PERMEABLE INHIBITORS OF TAU AGGREGATION AND THE ASSOCIATED NEURONAL DEGENERATION THAT CAN REACH THE CLINIC. DESPITE THEIR ASSOCIATION WITH DISEASE, AMYLOID FIBRILS ARE ALSO EXPLOITED FOR FUNCTIONAL PURPOSES BY DIFFERENT ORGANISMS. USING CRYO-ELECTRON MICROSCOPY (CRYO-EM), WE HAVE RECENTLY DETERMINED THE HIGH-RESOLUTION STRUCTURE OF THE FUNCTIONAL AMYLOID FIBRILS FORMED BY HNRNPDL-2, A HUMAN RNA-BINDING PROTEIN (RBP) ASSOCIATED WITH A RARE HEREDITARY MUSCULAR DYSTROPHY. THE STRUCTURE PROVIDES A MECHANISTIC EXPLANATION FOR THE PROTEIN ACTIVITY AND THE ORIGIN OF THE DISEASE. THERE ARE OTHER RBPS LINKED TO DISEASE, LIKE TIA1 IN AMYOTROPHIC LATERAL SCLEROSIS OR RBFOX1 IN AD, FOR WHICH THE FORMATION OF AMYLOIDS HAS BEEN DESCRIBED. NEVERTHELESS, THE STRUCTURE OF TIA1 AND RBFOX1 AGGREGATES AND THEIR CONNECTION TO PATHOLOGY ARE STILL UNKNOWN. WE WILL USE THE POWER OF CRYO-EM TO SHED LIGHT ON THESE ASPECTS. THE HIERARCHICAL AND TUNABLE ASSEMBLY OF AMYLOIDS MAKE THEM EXCEPTIONAL BUILDING BLOCKS IN NANOTECHNOLOGY. FUNCTIONAL AMYLOIDS LIKE HNRNPDL-2 HAVE BEEN EVOLUTIONARILY SELECTED TO BE HIGHLY ORDERED, MODULAR, STABLE, AND NON-TOXIC. WE WILL USE PROTEIN DESIGN AND ENGINEERING TO CONVERT THE AMYLOID HNRNPDL-2 SCAFFOLD INTO A BIOCOMPATIBLE NANOMATERIAL WITH APPLICATION IN T-CELL IMMUNOTHERAPY. OVERALL, WE INTEND TO EXPLOIT OUR EXPERTISE IN PROTEIN AGGREGATION TO PROVIDE THERAPEUTIC SOLUTIONS FOR NEURODEGENERATION, UNCOVER THE MOLECULAR ARCHITECTURE OF FUNCTIONAL AMYLOIDS AND BUILD UP NOVEL BIOCOMPATIBLE NANOMATERIALS.