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ALSのTDP-43のinclusion形成におけるVon Hippel-Lindau proteinの役割
The role of Von Hippel-Lindau protein in the formation of TDP-43 inclusions in ALS

  • P1-313
  • 内田 司 / Tsukasa Uchida:1 小代 明美 / Akemi Shodai:1 守村 敏史Toshihumi Morimura 辰巳 新水 / Shinsui Tatsumi:1 高橋 良輔 / Ryosuke Takahashi:1 漆谷 真 / Makoto Urushitani :1 
  • 1:京都大学 / Dept of Neurology Kyoto Univ. Hospital 

Backgrounds; The TAR DNA binding protein 43(TDP-43)is recognized as a primary protein component of intracellular inclusions in most cases of sporadic ALS. One of the pathological features of TDP-43 proteinopathies is a cytoplasmic deposition of TDP-43, the presence of which is associated with a concomitant loss of nuclear TDP-43. However, it remains unclear how TDP-43 induces ALS pathologies. Several studies showed that the failure to remove harmful aggregates causes neuronal cell death. Based on these findings, we aimed to clarify the molecular machineries involved in mishandling of misfolded TDP-43 in ALS. Methods; Our group attempted to identify interacting proteins with TDP-43, using a Reversible cross-linking during in vitro ubiquitination (ReCLIP, Smith AL, 2010) method, coupled with in vitro ubiquitination reaction. Immunoprecipitates were analyzed by LC-MS/MS. The molecular interaction was investigated using immunoprecipitation, Western blotting and immunofluorescence imaging from several cells subjected to transient transfection. Results; From the ReCLIP method, we identified Cullin-2 (CUL2), as a binding protein in response to ubiquitination of TDP-43 and von Hippel-Lindau (pVHL) as substrate recognition protein of CUL2. We confirmed the association between TDP-43 or CUL2 and pVHL by immunoprecipitation using culture cells. By immunoprecipitation assay using TDP-43 deletion mutants, pVHL showed lost considerable binding affinity to TDP-43 RRM2-deletion mutant than to wild type TDP-43, but showed a higher interaction to C-terminal deletion mutant. Moreover, it was found that pVHL preferentially recognized misfolded forms of TDP-43. The analysis for the subcellular localization revealed a co-localization of CUL2, pVHL and TDP-43 with cytoplasmic inclusions and also did co-localization with JUNQ proteins, including Hsp70 and ubiquitin. Surprisingly, no effect of pVHL-CUL2 on ubiquitination of TDP-43 was observed. Altogether, we identified pVHL, as a new TDP-43-interacting protein, which may be involved in aberrant compartmentization of misfolded TDP-43. Our results may highlight another machinery, linked to TDP-43 proteinopathy.

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