McLaren, M. W. | bioRxiv Science

bioRxiv2026

Encephalitic Alphavirus Infection Induces PARP-1 Hyperactivation Mediated Energy Collapse in Motor Neurons

Motor neurons are highly vulnerable to metabolic stress, yet the mechanisms driving their degeneration during neurotropic alphavirus infections remain unclear. Venezuelan equine encephalitis virus (VEEV) causes motor neuron injury, but the intrinsic pathways underlying this susceptibility are not fully defined. Previous work suggests alphavirus-infected motor neurons may die through caspase-independent mechanisms. Here, we show that VEEV infection induces sustained activation of the DNA repair enzyme poly(ADP-ribose) polymerase-1 (PARP-1), leading to depletion of NAD+ and ATP in murine NSC34 motor neuron-like cells and human iPSC-derived motor neurons. These metabolic changes precede mitochondrial depolarization and cell death. Pharmacological inhibition or genetic reduction of PARP-1 partially restores NAD+ and ATP and improves cell survival, indicating that PARP-1 hyperactivation directly contributes to energetic collapse and intrinsic motor neuron death. These results identify PARP-1 as a key driver of energy failure during VEEV infection and a potential target to limit neuronal injury in neurotropic viral infections.

microbiology↗

bioRxiv2025

Enterovirus D68 2A protease causes nuclear pore complex dysfunction and motor neuron toxicity

The picornavirus Enterovirus D68 (EV-D68) is an important pathogen associated with acute flaccid myelitis (AFM). The pathogenesis of AFM involves infection of spinal motor neurons and motor neuron death, however the mechanisms linking EV-D68 infection to selective neurotoxicity are not well understood. Dysfunction of the nuclear pore complex (NPC) has been implicated in motor neuron injury in neurodegenerative diseases such as amyotrophic lateral sclerosis, and the NPC is also modified by picornavirus proteases during the course of infection. We therefore sought to determine the impact of EV-D68 proteases on NPC composition and function. We demonstrate widespread disruption of NPC composition by EV-D68 2A and 3C proteases via the direct cleavage of a relatively small number of nucleoporins, notably Nup98 and POM121 by 2Apro. Using reporter systems, we demonstrate that 2Apro inhibits nuclear import and export of protein cargoes and also disrupts the permeability barrier of the NPC, while having no apparent effect on RNA export. Independently, we show that 2Apro is toxic to induced pluripotent stem cell derived motor neurons by demonstrating a rescue of toxicity with 2Apro inhibitor telaprevir at concentrations that are insufficient to inhibit viral replication. These findings expand our understanding of EV-D68 neuropathogenesis and provides a rationale for studying the NPC or 2Apro as therapeutic targets in AFM.

neuroscience↗