TDP-43: A New Class of Proteinopathies in Neurodegerative Diseases

Over the past decade it has become clear that there is significant overlap in the clinical phenotypes of frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS). The identification of TDP-43 as the major disease protein in the neuropathology of both FTLD with ubiquitin inclusions (FTLD-U) and ALS provides the first molecular link for these diseases and suggest that they belong to the same clinicopathological spectrum of disorder.
Pathological TDP-43 is abnormally phosphorylated, ubiquitinated, and cleaved to generate carboxy-terminal fragments in affected brain regions. The normal nuclear expression of TDP-43 is also reduced leading to the hypothesis that sequestration of TDP-43 in pathological inclusions contributes to disease pathogenesis. Thus, TDP-43 is the newest member of the growing list of neurodegenerative proteinopathies, but unique in that it lacks features of brain amyloidosis. Autosomal dominantly inherited TDP-43 mutations were also identified in familial ALS patients thereby suggesting a paradigm shift in our understanding on the etiology and pathogenesis of ALS. This presentation will provide an up-to-date summary of this very fast moving area of research.

Dr Virginia Lee