Postdoctoral scholar Cedars-Sinai Medical Center Los Angeles, California, United States
Abstract: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by the loss of motor neurons, resulting in muscle paralysis and eventual death. Emerging evidence suggests the importance of local RNA processing and protein homeostasis at neuromuscular junction (NMJ) synapse may play a critical role in disease progression. To explore this, we developed microfluidic "neuromuscular junction-chips," an innovative in vitro model system combining motor neurons and muscle cells derived from patient-induced pluripotent stem cells (iPSCs). This compartmentalized system provides unique opportunities to answer specific questions that are focused on local signaling at the NMJ. Our findings reveal critical components of the pre-mRNA splicing pathway in axons of iPSC-derived motor neurons and NMJ synapses in vivo, providing an intriguing link that splicing defects in ALS may be localized to NMJs. In C9ORF72-ALS, we observed compromised spliceosome pathways due to interactions with toxic C9 repeat RNA, leading to neurite degeneration and TDP-43 mis-localization—a hallmark of ALS pathology. We have recently developed a state-of-the-art single-cell proteomics approach to measure the proteome profile at the true single-cell resolution even in complex cell mixtures. To deepen our understanding of RNA-protein homeostasis, we applied this cutting-edge single-cell proteomics approach to measure proteomic and transcriptomic changes during motor neuron differentiation at single-cell resolution. This innovative strategy paves the way for future studies using NMJ-chips to quantitatively compare synaptic pre-mRNA processing and protein homeostasis at NMJs versus neuronal somas, and to unravel their alterations in C9-ALS.
Funding Source: Postdoctoral Fellowship, California Institute for Regenerative Medicine, EDUC4-12751
