| Summary: | 碩士 === 國立陽明大學 === 生化暨分子生物研究所 === 106 === Tar DNA binding protein of 43 kDa (TDP-43) is implicated in many biological processes and is identified as the principal component of neuronal inclusions in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar dementia. The C-terminal domain of TDP-43 (TDP-43C; residues 266–414) hosts almost all ALS-causing mutations, implying the importance of this domain. Moreover, TDP-43C interacting with hnRNPs abolishes RNA splicing ability and leads to TDP-43 aggregation, reinforcing the functional and pathological roles of the C-terminal domain. TDP-43C can undergo liquid-liquid phase separation (LLPS) and such ability is suggested relating to its pathological aggregation. In our previous work, we have demonstrated that the ALS-related mutations can alter phase separation and disrupt self-interaction through its middle alpha-helical part (~residues 320–340). However, the mechanism of condensate formation and its link to aggregation is still unclear. Here we studied the properties of condensate formation from two aspects: (I) to compare of the wild type (WT), ALS-related, and LLPS-motif-related mutants, and (II) to investigate the effects of the presence of its binding partner, hnRNP A2/B1. We applied nuclear magnetic resonance spectroscopy and several other biophysical tools to obtain structural information of condensate properties of TDP-43C variants and in complex with hnRNP A2/B1. We found that electrostatic force plays an important role in the condensate formation, as well as that a few aromatic residues sufficiently mediate its LLPS. We also found that TDP-43C and hnRNP A2/B1 weakly interact but the complex conformation changes in a time-dependent manner. The hnRNP A2/B1 significantly interrupt the condensate formation property of the TDP-43C WT. Our results provide a link between the disruption of TDP-43 function and its pathological aggregation.
|
|---|
