TDP-43 regulates retinoblastoma protein phosphorylation through the repression of cyclin-dependent kinase 6 expression
TDP-43 regulates retinoblastoma protein phosphorylation through the repression of cyclin-dependent kinase 6 expression
复制标题
DOI：
10.1073/pnas.0800546105
复制
发表时间：
2008-03-11
影响因子：
11.1
通讯作者：
Baralle, Francisco E.
中科院分区：
文献类型：
--
作者：
Ayala, Youhna M.;Misteli, Tom;Baralle, Francisco E.
TDP-43（TAR DNA结合蛋白）是一种高度保守的异质性核核糖核蛋白（hnRNP），参与特异性前mRNA剪接和转录事件。TDP-43最近已被确定为额颞叶变性（FTLD）和肌萎缩侧索硬化（ALS）这两种神经退行性疾病的细胞质内含物的主要成分。这种蛋白质的细胞作用仍有待确定。在这里，我们表明，TDP-43的损失导致畸形的核形状，细胞周期的失调，和凋亡。在人类细胞中去除TDP-43显著增加细胞周期蛋白依赖性激酶6（Cdk 6）蛋白和转录水平。由TDP-43介导的Cdk 6表达的控制涉及靶基因序列中的GT重复。Cdk 6在TDP-43耗竭细胞中的上调伴随着其两个主要靶点视网膜母细胞瘤蛋白pRb和pRb相关蛋白pRb 2/p130磷酸化的增加。TDP-43沉默还伴随着控制细胞增殖的几种因子的表达水平的变化。形态学核缺陷和TDP-43损失后的细胞凋亡增加是通过pRb途径介导的，因为pRb阴性细胞（Saos-2）在TDP-43去除后不经历程序性细胞死亡或核形状变形。我们的研究结果确定了TDP-43的调节靶点，并表明TDP-43的耗尽在人类细胞的基本代谢过程中具有重要的后果。
TDP-43 (for TAR DNA binding protein) is a highly conserved heterogeneous nuclear ribonucleoprotein (hnRNP) involved in specific pre-mRNA splicing and transcription events. TDP-43 recently has been identified as the main component of cytoplasmic inclusions in frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS), two neurodegenerative disorders. The cellular role of this protein remains to be identified. Here, we show that loss of TDP-43 results in dysmorphic nuclear shape, misregulation of the cell cycle, and apoptosis. Removal of TDP-43 in human cells significantly increases cyclin-dependent kinase 6 (Cdk6) protein and transcript levels. The control of Cdk6 expression mediated by TDP-43 involves GT repeats in the target gene sequence. Cdk6 up-regulation in TDP-43-depleted cells is accompanied by an increase in phosphorylation of two of its major targets, the retinoblastoma protein pRb and pRb-related protein pRb2/p130. TDP-43 silencing also is followed by changes in the expression levels of several factors that control cell proliferation. Morphological nuclear defects and increased apoptosis upon TDP-43 loss are mediated via the pRb pathway because pRb-negative cells (Saos-2) do not undergo programmed cell death or nuclear shape deformation upon TDP-43 removal. Our results identify a regulatory target of TDP-43 and show that TDP-43 depletion has important consequences in essential metabolic processes in human cells.