Ubiquilin-2 (UBQLN2) binds with high affinity to the C-terminal region of TDP-43 and modulates TDP-43 levels in H4 cells: characterization of inhibition by nucleic acids and 4-aminoquinolines.
Ubiquilin-2 (UBQLN2) binds with high affinity to the C-terminal region of TDP-43 and modulates TDP-43 levels in H4 cells: characterization of inhibition by nucleic acids and 4-aminoquinolines.
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DOI：
10.1016/j.bbapap.2013.03.020
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发表时间：
2013-06
影响因子：
3.2
通讯作者：
Reitz, Allen B.
中科院分区：
文献类型：
--
作者：
Cassel, Joel A.;Reitz, Allen B.
最近，有报道称泛素样蛋白泛素-2 （UBQLN2）的突变与x连锁肌萎缩性侧索硬化症（ALS）有关，并且野生型和突变型UBQLN2都可以与TAR DNA结合蛋白（TDP-43）的c端片段聚集体共定位。在这里，我们描述了UBQLN2和TDP-43之间的高亲和力相互作用，并证明UBQLN2和TDP-43的过表达降低了人H4细胞中外源性和内源性TDP-43的水平。UBQLN2与全长TDP-43和c端TDP-43片段（261-414 aa）均有高亲和力结合，KD值分别为6.2 nM和8.7 nM。结合TDP-43的DNA寡核苷酸和4-氨基喹啉也抑制UBQLN2与TDP-43的结合，与抑制寡核苷酸与TDP-43的结合具有相似的等级亲和力。抑制剂表征实验表明，DNA寡核苷酸非竞争性地抑制UBQLN2与TDP-43的结合，这与UBQLN2与TDP-43的c端结合一致。有趣的是，4-氨基喹啉类是UBQLN2与TDP-43结合的竞争性抑制剂，这表明这些化合物也结合TDP-43的c端区域。为了支持生化数据，共免疫沉淀实验表明TDP-43和UBQLN2在人神经胶质瘤H4细胞中相互作用。最后，在存在过表达的全长TDP-43或c端TDP-43（170-414）的情况下，UBQLN2过表达显著降低了全长TDP-43和c端TDP-43片段（CTFs）的水平。因此，这些数据表明UBQLN2增强了TDP-43和TDP-43 CTFs的清除，因此可能在TDP-43相关神经毒性的发展中发挥作用。
Recently, it was reported that mutations in the ubiqutin-like protein ubiquilin-2 (UBQLN2) are associated with X-linked amyotrophic lateral sclerosis (ALS), and that both wild-type and mutant UBQLN2 can co-localize with aggregates of C-terminal fragments of TAR DNA binding protein (TDP-43). Here, we describe a high affinity interaction between UBQLN2 and TDP-43 and demonstrate that overexpression of both UBQLN2 and TDP-43 reduces levels of both exogenous and endogenous TDP-43 in human H4 cells. UBQLN2 bound with high affinity to both full length TDP-43 and a C-terminal TDP-43 fragment (261-414 aa) with KD values of 6.2 nM and 8.7 nM, respectively. Both DNA oligonucleotides and 4-aminoquinolines, which bind to TDP-43, also inhibited UBQLN2 binding to TDP-43 with similar rank order affinities compared to inhibition of oligonucleotide binding to TDP-43. Inhibitor characterization experiments demonstrated that the DNA oligonucleotides noncompetitively inhibited UBQLN2 binding to TDP-43, which is consistent with UBQLN2 binding to the C-terminal region of TDP-43. Interestingly, the 4-aminoquinolines were competitive inhibitors of UBQLN2 binding to TDP-43, suggesting that these compounds also bind to the C-terminal region of TDP-43. In support of the biochemical data, co-immunoprecipation experiments demonstrated that both TDP-43 and UBQLN2 interact in human neuroglioma H4 cells. Finally, overexpression of UBQLN2 in the presence of overexpressed full length TDP-43 or C-terminal TDP-43 (170-414) dramatically lowered levels of both full length TDP-43 and C-terminal TDP-43 fragments (CTFs). Consequently, these data suggest that UBQLN2 enhances the clearance of TDP-43 and TDP-43 CTFs and therefore may play a role in the development of TDP-43 associated neurotoxicity.
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影响因子：
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作者：
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