Uncovering the role of perisynaptic schwann cells in C9ORF72 amyotrophic lateral sclerosis susceptibility and progression

The National Institute of Neurological Disorders and Stroke awarded The University of Chicago $100,228 on December 31, 2026, to support research on perisynaptic Schwann cells in C9ORF72 amyotrophic lateral sclerosis under the Extramural Research Programs in the Neurosciences and Neurological Disorders program (CFDA 93.853).

The research investigates why certain muscles are disproportionately vulnerable to degeneration in ALS while others remain spared—specifically why extraocular eye muscles are spared while the diaphragm is almost always affected. The project uses an AAV mouse model and neuromuscular organoids derived from patient-induced pluripotent stem cells to determine whether anatomical and molecular subtypes of perisynaptic Schwann cells at the neuromuscular junction confer vulnerability or resilience to ALS pathology. The recipient will employ confocal microscopy and single-cell RNA sequencing to characterize perisynaptic Schwann cell subtypes and their association with neuromuscular junctions of differential susceptibility to C9ORF72 ALS pathology.

The award period runs through September 29, 2029, with place of performance in Chicago, Illinois.

Abstract

Amyotrophic lateral sclerosis (ALS) is a devastating motoneuron degenerative disorder with a lack of effective treatments. Although ALS is considered a single disease, IT is largely heterogeneous in both its genetic etiology and its initial symptoms. Despite this heterogeneity, certain muscles are disproportionally affected and spared in all ALS patients regardless of genetic etiology and initial muscular onset. Remarkably, extraocular eye muscles are spared while the diaphragm is almost always affected in all ALS patients. Historically, this susceptibility has been studied from the neuronal or muscular perspective, but glial contribution remains largely understudied. An understudied population of glial cells at the neuromuscular junction (NMJ) are perisynaptic schwann cells (pscs), a subclass of non-myelinating schwann cells. Pscs have been implicated in development, maintenance, and repair of nmjs. However, PSC contributions to the susceptibility of selective muscle-typic NMJ dysfunction in ALS pathogenesis remains unknown. I aim to understand the contribution of pscs to NMJ susceptibility and disease progression of C9ORF72 ALS, the most common genetic cause in both familial and sporadic ALS, using both an AAV mouse model and neuromuscular organoids (nmos) from patient-derived induced pluripotent stem cells. I hypothesize that there are molecular and functional differences of pscs that confer vulnerability or resilience to NMJ dysfunction in ALS pathogenesis. In mice, i aim to determine the anatomical and molecular subtypes of pscs to uncover their association with nmjs of differential susceptibility to ALS pathology via confocal microscopy and single-cell RNA sequencing (aim 1). My preliminary results suggest that there are a differential number of pscs at different nmjs with more pscs at extraocular eye nmjs as compared to soleus and diaphragmatic nmjs, further supporting muscle-specific differences of pscs. Using nmos, which model spinal motor neuron connections to trunk skeletal muscle with functional nmjs with pscs, i aim to study pscs in a human ALS context, the first time this has been done to my knowledge. I will investigate the influence of well-known PSC receptors that detect synaptic transmission, muscarinic and purinergic receptors, on the control of PSC state (aim 2). Specifically, i will selectively increase the expression levels of these receptors in pscs only using cellreadr technology, "cell access through RNA sensing by endogenous adar" to determine their effect on PSC state as determined by molecular and functional outputs of the nmos. My preliminary studies have shown the ability to generate these organoids in our lab for the purposes of studying pscs. Understanding the contribution and mechanism of pscs to the selective pathogenesis of ALS will further our understanding of disease progression with a perspective on peripheral nervous system glia, allowing for identification of potential new therapeutic targets of ALS.