Phosphorylation of S409/410 of TDP-43 is a consistent feature in all sporadic and familial forms of TDP-43 proteinopathies
- 848 Downloads
Accumulation of hyperphosphorylated, ubiquitinated and N-terminally truncated TAR DNA-binding protein (TDP-43) is the pathological hallmark lesion in most familial and sporadic forms of FTLD-U and ALS, which can be subsumed as TDP-43 proteinopathies. In order to get more insight into the role of abnormal phosphorylation in the disease process, the identification of specific phosphorylation sites and the generation of phosphorylation-specific antibodies are mandatory. Here, we developed and characterized novel rat monoclonal antibodies (1D3 and 7A9) raised against phosphorylated S409/410 of TDP-43. These antibodies were used to study the presence of S409/410 phosphorylation by immunohistochemistry and biochemical analysis in a large series of 64 FTLD-U cases with or without motor neuron disease including familial cases with mutations in progranulin (n = 5), valosin-containing protein (n = 4) and linkage to chromosome 9p (n = 4), 18 ALS cases as well as other neurodegenerative diseases with concomitant TDP-43 pathology (n = 5). Our data demonstrate that phosphorylation of S409/410 of TDP-43 is a highly consistent feature in pathologic inclusions in the whole spectrum of sporadic and familial forms of TDP-43 proteinopathies. Physiological nuclear TDP-43 was not detectable with these mAbs by immunohistochemistry and by immunoblot analyses. While the accumulation of phosphorylated C-terminal fragments was a robust finding in the cortical brain regions of FTLD-U and ALS, usually being much more abundant than the phosphorylated full-length TDP-43 band, spinal cord samples revealed a predominance of full-length TDP-43 over C-terminal fragments. This argues for a distinct TDP-43 species composition in inclusions in cortical versus spinal cord cells. Overall, these mAbs are powerful tools for the highly specific detection of disease-associated abnormal TDP-43 species and will be extremely useful for the neuropathological routine diagnostics of TDP-43 proteinopathies and for the investigation of emerging cellular and animal models for TDP-43 proteinopathies.
Work was supported by grants from the Deutsche Forschungsgemeinschaft (SFB 596) and the Federal Ministry of Education and Research (01GI0704) as well as from the NIH (AG10124 and AG17586). MN is funded by the Stavros-Niarchos Foundation and the Synapsis Foundation. We thank Iryna Pigur and Mareike Schroff for excellent technical assistance.
- 16.Igaz LM, Kwong LK, Xu Y et al (2008) Enrichment of C-terminal fragments in TAR DNA-binding protein-43 cytoplasmic inclusions in brain but not in spinal cord of frontotemporal lobar degeneration and amyotrophic lateral sclerosis. Am J Pathol 173:182–194. doi: 10.2353/ajpath.2008.080003 PubMedCrossRefGoogle Scholar
- 20.Kwong LK, Neumann M, Sampathu DM, Lee VM, Trojanowski JQ (2007) TDP-43 proteinopathy: the neuropathology underlying major forms of sporadic and familial frontotemporal lobar degeneration and motor neuron disease. Acta Neuropathol 114:63–70. doi: 10.1007/s00401-007-0226-5 PubMedCrossRefGoogle Scholar
- 33.Sampathu DM, Neumann M, Kwong LK et al (2006) Pathological heterogeneity of frontotemporal lobar degeneration with ubiquitin-positive inclusions delineated by ubiquitin immunohistochemistry and novel monoclonal antibodies. Am J Pathol 169:1343–1352. doi: 10.2353/ajpath.2006.060438 PubMedCrossRefGoogle Scholar