Autoregulation of Fox protein expression to produce dominant negative splicing factors
Autoregulation of Fox protein expression to produce dominant negative splicing factors
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DOI：
10.1261/rna.1838210
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发表时间：
2010-02-01
期刊：
影响因子：
4.5
通讯作者：
Black, Douglas L.
中科院分区：
文献类型：
--
作者：
Damianov, Andrey;Black, Douglas L.
Fox蛋白是控制神经元、肌肉和其他组织中许多外显子的选择性剪接的调节家族。fox1 （A2BP1）、fox2 （RBM9）和fox3 （HRNBP3）这三种哺乳动物的类似物，每一种都产生具有单个rna结合结构域（RRM）的蛋白质，其两侧是N端和c端结构域，这些结构域通过使用不同的启动子和不同的剪接模式而高度多样化。由于一个高度保守的93-nt外显子的跳跃，这些基因还表达缺乏RRM后半部分（Fox Delta RRM）的蛋白质同工型。Fox结合元件在Fox-1和Fox-2中重叠这些外显子的剪接位点，Fox蛋白本身抑制外显子的包含。与rna结合蛋白剪接自动调节的其他情况不同，跳过RRM外显子会在mRNA中产生框内缺失，从而产生稳定的蛋白质。这些由cDNA表达的Fox Delta RRM异构体在体内表现出与RNA高度降低的结合。然而，我们发现它们可以作为Fox依赖剪接的抑制因子，可能是通过与全长Fox同种异构体竞争与其他剪接因子的相互作用。有趣的是，果蝇狐狸的同源基因在其RRM结构域中包含一个几乎相同的外显子，该外显子也有狐狸的结合位点。因此，Fox蛋白不是通过剪接的自动调节来控制调节因子的丰度，而是使用高度保守的剪接自动调节机制来控制显性负异构体的产生。
The Fox proteins are a family of regulators that control the alternative splicing of many exons in neurons, muscle, and other tissues. Each of the three mammalian paralogs, Fox-1 (A2BP1), Fox-2 (RBM9), and Fox-3 (HRNBP3), produces proteins with a single RNA-binding domain (RRM) flanked by N- and C-terminal domains that are highly diversified through the use of alternative promoters and alternative splicing patterns. These genes also express protein isoforms lacking the second half of the RRM (Fox Delta RRM), due to the skipping of a highly conserved 93-nt exon. Fox binding elements overlap the splice sites of these exons in Fox-1 and Fox-2, and the Fox proteins themselves inhibit exon inclusion. Unlike other cases of splicing autoregulation by RNA-binding proteins, skipping the RRM exon creates an in-frame deletion in the mRNA to produce a stable protein. These Fox Delta RRM isoforms expressed from cDNA exhibit highly reduced binding to RNA in vivo. However, we show that they can act as repressors of Fox-dependent splicing, presumably by competing with full-length Fox isoforms for interaction with other splicing factors. Interestingly, the Drosophila Fox homolog contains a nearly identical exon in its RRM domain that also has flanking Fox-binding sites. Thus, rather than autoregulation of splicing controlling the abundance of the regulator, the Fox proteins use a highly conserved mechanism of splicing autoregulation to control production of a dominant negative isoform.