Antibody against TDP-43 phosphorylated at serine 375 suggests conformational differences of TDP-43 aggregates among FTLD –TDP subtypes

AbstractAggregation of hyperphosphorylated TDP-43 is the hallmark pathological feature of the most common molecular form of frontotemporal lobar degeneration (FTLD –TDP) and in the vast majority of cases with amyotrophic lateral sclerosis (ALS–TDP). However, most of the specific phosphorylation sites remain to be determined, and their relevance regarding pathogenicity and clinical and pathological phenotypic diversity in FTLD–TDP and ALS–TDP remains to be identified. Here, we generated a novel antibody raised against TDP-43 phosphorylated at serine 375 (pTDP-43S375) located in the low-complexity domain, and used it to investigate the presence of S375 phosphorylation in a series (n = 44) of FTLD–TDP and ALS–TDP cases. Immunoblot analysis demonstrated phosphorylation of S375 to be a consistent feature of pathological TDP-43 species, including full-length and C-terminal fragments, in all FTLD–TDP subtypes examined (A–C) and in ALS–TDP. Of particular interest, howe ver, detailed immunohistochemical analysis showed striking differences in the immunoreactivity profile of inclusions with the pTDP-43S375 antiserum among pathological subtypes. TDP-43 pathology of ALS –TDP, FTLD–TDP type B (including cases with theC9orf72 mutation), and FTLD –TDP type C all showed strong pTDP-43S375 immunoreactivity that was similar in amount and morphology to that seen with an antibody against TDP-43 phosphorylated at S409/410 used as the gold standard. In stark contrast, T...

Source: Acta Neuropathologica - August 9, 2020 Category: Neurology Source Type: research