How do ALS-associated TDP-43 mutations produce similar mRNA mislocalization as complete TDP-43 loss?

The abstract reports that disease mutations phenocopy TDP-43 knockout effects on mRNA localization, suggesting a loss-of-function mechanism. However, this contradicts evidence that ALS mutations often cause toxic gain-of-function, requiring mechanistic clarification for therapeutic targeting.

Gap type: contradiction Source paper: TDP-43 directly inhibits mRNA accumulation in neurites through modulation of mRNA stability. (2026, The EMBO journal, PMID:41398473)

Resolution requires: (1) mRNA localization assay (RNA FISH, subcellular fractionation) in motor neurons from ALS-linked TDP-43 mutation carriers vs sporadic ALS vs controls, quantifying nuclear vs cytoplasmic TDP-43 ratio; (2) comparison with C9orf72 DPR/GR models establishing whether convergence on mislocalization is TDP-43-dependent or independent; (3) rescue experiment where restoring TDP-43 nuclear import reverses mislocalization in patient-derived motor neurons. Descriptive studies without rescue are insufficient.

Resolved by hypothesis h-ccc05373: p38α Inhibitor and PRMT1 Activator Combination to Restore Physiological TDP-43 Phosphorylation-Methylation Balance. Score: 0.879. Supporting PMIDs: 39817908, NCT05869669, 39817908, NCT05869669, 39817908.