Studies of NMJ structure and function in mutant FUS-ALS and beyond

Pasinelli, Piera

Abstract

The overall goal of this proposal is to unravel functional and molecular defects of neuromuscular synaptic transmission at the level of the neuromuscular junction in Amyotrophic Lateral Sclerosis (ALS). We propose to use ALS-related Fused-in sarcoma (FUS) as a prototype protein to identify neuromuscular junction (NMJ) targets of disease and to unravel the mechanisms by which ALS-linked FUS mutations alter the function of the NMJ, which is a prominent feature of ALS. Specifically, we propose to identify critical synaptic proteins targeted by mutant FUS in the terminal axon of the pre-synaptic motor neuron at NMJ. With the use of human iPS cells-derived motor neuron/muscle co- cultures from different sub-groups of patients (mutant FUS, SOD1, C9Orf72 and sporadic), we will in addition compare synaptic targets impaired by mutant FUS with those potentially impaired by other ALS-related genetic and environmental stressors. Ultimately, we will identify FUS specific vs. common ALS NMJ targets. Our plan is to employ a systematic, step-based and collaborative research approach that uses multiple research tools and disease models, each with its own characteristics and strengths. We will combine the expertise of the Pasinelli laboratory in studying molecular pathogenic mechanisms in ALS in disease relevant cells/systems with the experience of the Maragakis' lab in using and characterizing iPS cells to: (1) Investigate the cellular and molecular mechanisms of mutant FUS-induced dysfunction of the NMJ; (2) Identify FUS- specific and common targets of NMJ dysfunction in ALS patients, ultimately for biomarker identification and drug discovery.

Public Health Relevance

Amyotrophic Lateral Sclerosis (ALS) is an incurable paralytic disorder due to death of motor neurons, the cells that send impulses to the muscles and control all movements throughout the body. This loss of communication between the motor neurons and the muscles is the hallmark of all forms of ALS and, perhaps, the only common denominator in this highly heterogeneous disease. Here, we will use rodent as well as patient-derived motor neurons (derived from an heterogeneous patient's population) cultured in petri dishes with muscles as simple experimental models to identify the specific changes in the function of the motor neurons that make them defective in sending messages to the muscle, with the goal of finding disease biomarkers and identifying intervention therapies to maintain muscle strength in patients longer.