Aggregation and antibody‐based inhibition of TDP‐43

Abstract

Background TAR DNA‐binding protein 43 (TDP‐43) is a highly conserved nuclear protein, predominantly associated with RNA metabolism. Aberrant TDP‐43 inclusions are present in over 95% of post‐mortem brain tissue samples from Amyotrophic Lateral Sclerosis (ALS) patients. The highly disordered TDP‐43 C‐Terminal Domain (CTD) is associated with the greatest amount of disease‐related mutations and phosphorylation sites. The exact mechanism of TDP‐43 aggregation and formation into a pathological state has yet to be elucidated but is an important therapeutic target to consider. Method Full‐length phosphorylated TDP‐43 (pS410) protein was treated with 6 hours of daily agitation over 9 days in vitro. Agitation and aging took place with and without the presence of TDP‐43 RRM2‐CTD specific antibodies. Dot‐blot analysis was performed to confirm the binding of antibodies to TDP‐43. Aggregation was monitored and characterized using biophysical analysis; methods included Thioflavin T (ThT), turbidity, and transmission electron microscopy (TEM). Result Phospho‐TDP‐43 that had undergone agitation and extensive aging formed insoluble aggregates and ThT positive fibrils. The incubation with antibodies specific to the RRM2‐CTD inhibited aggregation and fibril formation in a concentration‐dependent manner. Conclusion Similar immunotherapies exist for other neurodegenerative disease‐related proteins; inhibition of TDP‐43 aggregation and fibril formation using antibodies demonstrates the potential for the epitope‐specific treatment of TDP‐43 proteinopathies. 1) Esposto, J., & Martic‐Milne, S. (2021). Biochimica et Biophysica Acta (BBA) ‐ Molecular Basis of Disease, 1867, https://doi.org/10.1016/j.bbadis.2021.166234.