TDP-43 Phosphorylation by casein kinase Iε promotes oligomerization and enhances toxicity in vivo
TDP-43 Phosphorylation by casein kinase Iε promotes oligomerization and enhances toxicity in vivo
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DOI：
10.1093/hmg/ddt498
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发表时间：
2014-02-15
影响因子：
3.5
通讯作者：
Jackson, George R.
中科院分区：
文献类型：
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作者：
Choksi, Darshana K.;Roy, Bidisha;Jackson, George R.
交互反应dna结合蛋白43 （TDP-43）的显性突变导致肌萎缩侧索硬化症。TDP-43包涵体见于本病的神经元、胶质细胞和肌肉以及散发性和遗传性额颞叶变性。Ser409/410表位上TDP-43的细胞质定位、裂解、聚集和磷酸化与疾病发病有关。TDP-43聚集并不是TDP-43蛋白病小鼠模型的共同特征，通常认为TDP-43不会获得淀粉样构象或形成原纤维。已经确定了一些推测的TDP-43激酶，但这些激酶是否具有调节TDP-43磷酸化或体内毒性的功能尚不清楚。在这里，我们证明了与野生型和M337V型相比，人类TDP-43（Q331K）在果蝇中错误表达时经历了细胞质定位和聚集。Q331K与苍蝇同源的酪蛋白激酶（CKI?）双时间（DBT）共表达，增强了毒性。在果蝇中，错误表达的人TDP-43最多有适度的基础磷酸化，但与DBT共表达会增加所有TDP-43亚型的Ser409/410磷酸化。在果蝇中，TDP-43的磷酸化是DBT特异性的，因为使用已验证的tau激酶GSK-3、PAR-1/MARK2或CDK5没有观察到它。DBT与TDP-43（Q331K）共表达促进了高分子量低聚物的形成，同时增强了毒性，重组低聚物TDP-43与大鼠CKI处理强烈增强了其在哺乳动物细胞培养中的毒性。这些数据表明CKIe在体内是一种有效的TDP-43激酶，并暗示低聚物物种是TDP-43蛋白病变的毒性实体。
Dominant mutations in transactive response DNA-binding protein-43 (TDP-43) cause amyotrophic lateral sclerosis. TDP-43 inclusions occur in neurons, glia and muscle in this disease and in sporadic and inherited forms of frontotemporal lobar degeneration. Cytoplasmic localization, cleavage, aggregation and phosphorylation of TDP-43 at the Ser409/410 epitope have been associated with disease pathogenesis. TDP-43 aggregation is not a common feature of mouse models of TDP-43 proteinopathy, and TDP-43 is generally not thought to acquire an amyloid conformation or form fibrils. A number of putative TDP-43 kinases have been identified, but whether any of these functions to regulate TDP-43 phosphorylation or toxicity in vivo is not known. Here, we demonstrate that human TDP-43(Q331K) undergoes cytoplasmic localization and aggregates when misexpressed in Drosophila when compared with wild-type and M337V forms. Coexpression of Q331K with doubletime (DBT), the fly homolog of casein kinase Ie (CKI?), enhances toxicity. There is at best modest basal phosphorylation of misexpressed human TDP-43 in Drosophila, but coexpression with DBT increases Ser409/410 phosphorylation of all TDP-43 isoforms tested. Phosphorylation of TDP-43 in the fly is specific for DBT, as it is not observed using the validated tau kinases GSK-3, PAR-1/MARK2 or CDK5. Coexpression of DBT with TDP-43(Q331K) enhances the formation of high-molecular weight oligomeric species coincident with enhanced toxicity, and treatment of recombinant oligomeric TDP-43 with rat CKI strongly enhances its toxicity in mammalian cell culture. These data identify CKIe as a potent TDP-43 kinase in vivo and implicate oligomeric species as the toxic entities in TDP-43 proteinopathies.