CUL2-mediated clearance of misfolded TDP-43 is paradoxically affected by VHL in oligodendrocytes in ALS.
CUL2-mediated clearance of misfolded TDP-43 is paradoxically affected by VHL in oligodendrocytes in ALS.
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DOI：
10.1038/srep19118
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发表时间：
2016-01-11
影响因子：
4.6
通讯作者：
Urushitani M
中科院分区：
文献类型：
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作者：
Uchida T;Tamaki Y;Ayaki T;Shodai A;Kaji S;Morimura T;Banno Y;Nishitsuji K;Sakashita N;Maki T;Yamashita H;Ito H;Takahashi R;Urushitani M
肌萎缩侧索硬化症(ALS)中导致TDP-43错误折叠的胞浆积聚的分子机制仍然不清楚。在这里，我们确定了一个cullin-2(CUL2)环复合体作为一种新的泛素连接酶，用于TDP-43的碎片化形式。Von Hippel Lindau蛋白(VHL)是该复合体的底物结合成分，在RNA识别基序2的Glu246位优先识别错误折叠的TDP-43。重组的全长TDP-43结构脆弱且容易切割，表明错误折叠的TDP-43可被VHL/CUL2通过片段分步清除。令人惊讶的是，过量的VHL稳定并导致TDP-43和突变体SOD1在核旁蛋白质量控制中心形成包涵体。此外，TDP-43下调培养细胞中VHL的表达，表明VHL与ALS中错误定位的TDP-43之间存在异常相互作用。最后，ALS脊髓内的胞浆内含物，特别是少突胶质细胞内的胞质包涵体对磷酸化的TDP-43和VHL均呈免疫反应。因此，我们的结果提示，VHL和CUL2的失衡可能是ALS少突胶质细胞功能障碍的原因，并强调CUL2 E3连接酶作为ALS的一种新的治疗潜力出现。
The molecular machinery responsible for cytosolic accumulation of misfolded TDP-43 in amyotrophic lateral sclerosis (ALS) remains elusive. Here we identified a cullin-2 (CUL2) RING complex as a novel ubiquitin ligase for fragmented forms of TDP-43. The von Hippel Lindau protein (VHL), a substrate binding component of the complex, preferentially recognized misfolded TDP-43 at Glu246 in RNA-recognition motif 2. Recombinant full-length TDP-43 was structurally fragile and readily cleaved, suggesting that misfolded TDP-43 is cleared by VHL/CUL2 in a step-wise manner via fragmentation. Surprisingly, excess VHL stabilized and led to inclusion formation of TDP-43, as well as mutant SOD1, at the juxtanuclear protein quality control center. Moreover, TDP-43 knockdown elevated VHL expression in cultured cells, implying an aberrant interaction between VHL and mislocalized TDP-43 in ALS. Finally, cytoplasmic inclusions especially in oligodendrocytes in ALS spinal cords were immunoreactive to both phosphorylated TDP-43 and VHL. Thus, our results suggest that an imbalance in VHL and CUL2 may underlie oligodendrocyte dysfunction in ALS, and highlight CUL2 E3 ligase emerges as a novel therapeutic potential for ALS.