Pathological Comparison of TDP-43 Between Motor Neurons and Interneurons Expressed by a Tetracycline Repressor System on the Mouse Artificial Chromosome

Background Cytoplasmic mislocalization of TAR -DNA binding protein of 43 kDa (TDP-43) is a major hallmark of amyotrophic lateral sclerosis (ALS). TDP-43 aggregation is detected in the cortical and spinal motor neurons in most ALS cases; however, pathological mechanism of this mislocalized TDP-43 remains unknown.Methods We generated a tetracycline-inducible TDP-43 A315T system on a mouse artificial chromo-some (MAC) vector to avoid transgene-insertional mu-tagenesis, established a mouse embryonic stem (ES) cell line holding this MAC vector system, and investigated whether overexpressed exogenous TDP-43 A315T was mislocalized in the cytoplasm of the ES cell-derived neurons and triggered the neurotoxic effects on these cells.Results Inducible TDP-43 A315T system was suc-cessfully loaded onto the MAC and introduced into the mouse ES cells. These ES cells could differentiate into motor neurons and interneurons. Overexpression of TDP-43 A315T by addition of doxycycline in both neurons resulted in mislocalization to cytoplasm. Mislocalized TDP-43 caused cell death of motor neu-rons, but not interneurons.Conclusion Vulnerability to cytoplasmic mislocal-ized TDP-43 is selective on neuronal types, whereas mislocalization of overexpressed TDP-43 occurs in even insusceptible neurons. This inducible gene expression system using MAC remains useful for providing critical insights into appearance of TDP-43 pathology.

Automated summary

Cytoplasmic mislocalization of TDP-43 is a major characteristic of ALS. Researchers generated a TDP-43 A315T system on a mouse artificial chromosome and investigated its neurotoxic effects on mouse ES cell-derived neurons. Overexpression of TDP-43 A315T resulted in cytoplasmic mislocalization and subsequent cell death in motor neurons.