Department of Molecular Pathology, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy.
EMBO J. 2011 Jan 19;30(2):277-88. doi: 10.1038/emboj.2010.310. Epub 2010 Dec 3.
TAR DNA-binding protein (TDP-43) is an evolutionarily conserved heterogeneous nuclear ribonucleoprotein (hnRNP) involved in RNA processing, whose abnormal cellular distribution and post-translational modification are key markers of certain neurodegenerative diseases, such as amyotrophic lateral sclerosis and frontotemporal lobar degeneration. We generated human cell lines expressing tagged forms of wild-type and mutant TDP-43 and observed that TDP-43 controls its own expression through a negative feedback loop. The RNA-binding properties of TDP-43 are essential for the autoregulatory activity through binding to 3' UTR sequences in its own mRNA. Our analysis indicated that the C-terminal region of TDP-43, which mediates TDP-43-hnRNP interactions, is also required for self-regulation. TDP-43 binding to its 3' UTR does not significantly change the pre-mRNA splicing pattern but promotes RNA instability. Moreover, blocking exosome-mediated degradation partially recovers TDP-43 levels. Our findings demonstrate that cellular TDP-43 levels are under tight control and it is likely that disease-associated TDP-43 aggregates disrupt TDP-43 self-regulation, thus contributing to pathogenesis.
TAR DNA 结合蛋白（TDP-43）是一种进化上保守的异质核核糖核蛋白（hnRNP），参与 RNA 加工，其细胞内分布异常和翻译后修饰是某些神经退行性疾病的关键标志物，如肌萎缩性侧索硬化症和额颞叶变性。我们生成了表达标记形式的野生型和突变型 TDP-43 的人类细胞系，并观察到 TDP-43 通过负反馈环控制自身表达。TDP-43 的 RNA 结合特性对于通过与其自身 mRNA 的 3'UTR 序列结合的自动调节活性至关重要。我们的分析表明，TDP-43 的 C 端区域介导 TDP-43-hnRNP 相互作用，对于自我调节也是必需的。TDP-43 与其 3'UTR 的结合不会显著改变前体 mRNA 的剪接模式，但会促进 RNA 不稳定性。此外，阻断外泌体介导的降解部分恢复 TDP-43 水平。我们的研究结果表明，细胞内 TDP-43 水平受到严格控制，并且与疾病相关的 TDP-43 聚集体可能破坏 TDP-43 的自我调节，从而导致发病机制。
