Biology subjects

Sundali, S.

Publications and source records attributed to Sundali, S..

2 recordsLinked to original sources

bioRxiv2026

Mitochondrial NAD+ import gates neuronal resilience to active SARM1

SARM1 is an inducible NADase that executes pathological axon degeneration, but how NAD+ destruction causes neuronal failure remains unclear. Because SARM1 is predicted to act outside the mitochondrial matrix, cytosolic NAD+ loss has been viewed as the critical lethal lesion. We show that SARM1 activation rapidly depletes cytosolic and mitochondrial NAD+ and collapses ATP in both compartments, revealing early, coupled metabolic failure. Enhancing mitochondrial NAD+ import through SLC25A51, the mitochondrial NAD+ transporter, preserves mitochondrial NAD+, maintains mitochondrial function, and delays axon degeneration and neuronal death despite ongoing SARM1 activity. Unexpectedly, SLC25A51 restores cytosolic NAD+-dependent metabolism, reversing a glycolytic block and increasing NAD+ synthesis during stress. Glycolytic inhibition attenuates protection, identifying cytosolic metabolic recovery as an important component of neuronal resilience. AAV-SLC25A51 improves function in a chronic SARM1-dependent neuropathy model. Thus, mitochondrial NAD+ import gates SARM1-driven degeneration by limiting coupled mitochondrial-cytosolic metabolic failure, presenting a downstream intervention point for axon preservation.

neuroscience↗

bioRxiv2025

TDP-43 suppression of ATP8A2 cryptic splicing implicates phosphatidylserine-driven neuroinflammation in ALS/FTD

Inappropriate externalization of phosphatidylserine (PS) is a candidate mechanism of pathogenic neuroinflammation, a critical driver of neurodegenerative disease. ATP8A2, a flippase that maintains PS on the plasma membrane inner leaflet, is mutated in both Wabbler-lethal mice and patients with the ataxia syndrome CAMRQ4. Here, we identify ATP8A2 as a target of TDP-43 cryptic exon suppression, and demonstrate that ATP8A2 loss leads to immune-mediated neurodegeneration. ATP8A2 splicing is significantly dysregulated following TDP-43 depletion in human neurons and in brains of patients with Amyotrophic Lateral Sclerosis-Frontotemporal Dementia (ALS-FTD). In mice, Atp8a2 loss increases PS exposure and promotes neuroinflammation. Depletion of peripheral macrophages rescues motor axon degeneration and doubles Atp8a2 knockout mouse lifespan, while depletion of both peripheral macrophages and central microglia quadruples lifespan and improves coordination. Hence, ATP8A2 is a pathologically relevant TDP-43 target and inhibition of phagocytic immune cell attack against neurons is a potential treatment for patients with CAMRQ4 and ALS-FTD.

neuroscience↗