TDP-43 Dysfunction Causes Hyper-Lactate State, Increased AARS1 Expression and Enhanced Protein Lactylation.

Objective abnormal function of TAR DNA-binding protein of 43 (TDP-43) is closely associated with the development of various neurodegenerative diseases. Previous studies have shown that TDP-43 dysfunction induces mitochondrial damage. However, whether TDP-43 dysfunction further promotes lactate accumulation and enhances protein lactylation remains unclear. This study aimed to investigate the effects of TDP-43 loss-of-function on lactate metabolism and protein lactylation. Methods a neuron-specific TDP-43 conditional knockout mouse model (TDP-43 cKO mice) and a TDP-43 knockdown NSC34 cell model were established. Survival was recorded and motor function was monitored in TDP-43 cKO mice. Mitochondrial morphology and mitochondrial DNA (mtDNA) leakage were examined by high-speed structured illumination microscopy (HIS-SIM). L-lactate levels were quantified using an L-lactate detection kit. TDP-43 and AARS1 mRNA levels were measured by RT-qPCR. The degree of protein pan-lactylation and the expression of TDP-43 and AARS1 were analyzed by Western blot. Results TDP-43 cKO mice exhibited motor deficits and shortened lifespan. In the TDP-43 knockdown cell model, TDP-43 deficiency caused marked mitochondrial structural and functional abnormalities, including reduced mitochondrial number and perimeter, mtDNA leakage, decreased mitochondrial membrane potential, reduced ATP production and impaired cell viability. In both the motor cortex of TDP-43 cKO mice and cell model, L-lactate levels, pan-lactylation, and AARS1 expression were significantly increased. In addition, sodium lactate treatment further enhanced pan-lactylation and AARS1 protein expression in NSC34 cells. Conclusion TDP-43 deficiency induces mitochondrial injury and is associated with lactate accumulation, increased protein lactylation, and AARS1 upregulation. These findings provide new insights into the mechanisms underlying TDP-43 loss-of-function-mediated neurodegeneration and suggest potential therapeutic targets for TDP-43-related neurodegenerative diseases.