The human TAR DNA-binding protein (TDP43) colocalizes with ubiquitinated 
inclusions in motor neurons in amyotrophic lateral sclerosis (ALS). TDP43 is 
both a DNA-binding protein with a nuclear export sequence that interacts with 
(TG)nTm elements in DNA and an RNA-binding protein that interacts with 
(UG)(6-12) motifs in single-stranded RNA. In control motor neurons, TDP43 was 
almost exclusively nuclear, whereas in ALS spinal motor neurons, TDP43 was 
predominantly localized to the cytosol and not the nucleus. TDP43 was observed 
as punctuate immunoreactivity and as dense skeins, with and without 
ubiquitinization. We observed that TDP43 stabilizes the human low molecular 
weight (hNFL) mRNA through a direct interaction with the 3'UTR. TDP43 is a 
unique hNFL mRNA-binding protein that is altered in its somatotopic localization 
in ALS spinal motor neurons and potentially contributes to the formation of NF 
aggregates in ALS through alterations in NF stoichiometry.