Research report14-3-3 eta isoform colocalizes TDP-43 on the coarse granules in the anterior horn cells of patients with sporadic amyotrophic lateral sclerosis

- We demonstrated localization of 14-3-3 eta in anterior horn cells of ALS.
- The co-localization between p-TDP-43 and the eta isoform was seen.
- The p-TDP-43-positive “inclusion” was negative for the eta isoform.
- The eta isoform and SNAP25 showed partial colocalization in the AHCs.

The immunolocalization of the 14-3-3 eta isoform in the anterior horn cells (AHCs) of patients with sporadic amyotrophic lateral sclerosis (ALS) and controls was examined. Compared with the immunolocalization of other 14-3-3 isoforms, the immunolocalization of the 14-3-3 eta isoform was either synaptic at the periphery of AHCs, spindle-shaped in neurites, or granular in the cytoplasm. By double labeling with phosphorylated (p-)TDP-43, the transactivation response DNA binding protein of 43 kDa (TDP-43) demonstrated frequent colocalization of the 14-3-3 eta isoform in granular structures (90%) and spindle-shaped structures (85.4%), but not in p-TDP-43-positive round inclusions. It is speculated that the 14-3-3 eta isoform is associated with not only a synaptic pathology of ALS but also TDP-positive small lesions in the cytoplasm and neurites. The absence of eta-like immunoreactivity in p-TDP-43-positive large inclusions suggests the restricted relevance of the 14-3-3 eta isoform during ALS pathogenesis to some phases of the p-TDP pathology.