Department of Neurology, Lurie Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
J Mol Neurosci. 2011 Nov;45(3):453-66. doi: 10.1007/s12031-011-9634-z. Epub 2011 Sep 1.
Microtubule binding protein Tau has been implicated in a wide range of neurodegenerative disorders collectively classified as tauopathies. Exon 10 of the human tau gene, which codes for a microtubule binding repeat region, is alternatively spliced to form Tau protein isoforms containing either four or three microtubule binding repeats, Tau4R and Tau3R, respectively. The levels of different Tau splicing isoforms are fine-tuned by alternative splicing with the ratio of Tau4R/Tau3R maintained approximately at one in adult neurons. Mutations that disrupt tau exon 10 splicing regulation cause an imbalance of different tau splicing isoforms and have been associated with tauopathy. To search for factors interacting with tau pre-messenger RNA (pre-mRNA) and regulating tau exon 10 alternative splicing, we performed a yeast RNA-protein interaction screen and identified polypyrimidine tract binding protein associated splicing factor (PSF) as a candidate tau exon 10 splicing regulator. UV crosslinking experiments show that PSF binds to the stem-loop structure at the 5' splice site downstream of tau exon 10. This PSF-interacting RNA element is distinct from known PSF binding sites previously identified in other genes. Overexpression of PSF promotes tau exon 10 exclusion, whereas down-regulation of the endogenous PSF facilitates exon 10 inclusion. Immunostaining shows that PSF is expressed in the human brain regions affected by tauopathy. Our data reveal a new player in tau exon 10 alternative splicing regulation and uncover a previously unknown mechanism of PSF in regulating tau pre-mRNA splicing.
微管结合蛋白 Tau 与广泛的神经退行性疾病有关，这些疾病统称为 Tau 病。人类 Tau 基因的外显子 10 编码微管结合重复区，可通过选择性剪接形成含有四个或三个微管结合重复的 Tau 蛋白异构体，分别为 Tau4R 和 Tau3R。不同 Tau 剪接异构体的水平通过选择性剪接进行微调，Tau4R/Tau3R 的比例在成年神经元中保持在大约 1。破坏 Tau 外显子 10 剪接调节的突变导致不同 Tau 剪接异构体的失衡，并与 Tau 病有关。为了寻找与 Tau 前信使 RNA（pre-mRNA）相互作用并调节 Tau 外显子 10 选择性剪接的因子，我们进行了酵母 RNA-蛋白质相互作用筛选，并鉴定出多嘧啶 tract 结合蛋白相关剪接因子（PSF）作为 Tau 外显子 10 剪接调节剂的候选物。UV 交联实验表明，PSF 与 Tau 外显子 10 下游 5'剪接位点的茎环结构结合。这个 PSF 相互作用的 RNA 元件与先前在其他基因中鉴定的已知 PSF 结合位点不同。PSF 的过表达促进 Tau 外显子 10 的排除，而内源性 PSF 的下调促进外显子 10 的包含。免疫染色显示 PSF 在受 Tau 病影响的人类大脑区域表达。我们的数据揭示了 Tau 外显子 10 选择性剪接调节的新参与者，并揭示了 PSF 调节 Tau 前 mRNA 剪接的先前未知机制。
