Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, USA.
Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, USA.
Sci Rep. 2017 Jun 20;7(1):3848. doi: 10.1038/s41598-017-03180-3.
Epithelial-Splicing-Regulatory-Protein 1 (Esrp1) is a cell-type specific RNA-binding protein (RBP) that is essential for mammalian development through maintenance of epithelial cell properties including barrier function. Esrp1 also regulates splicing during the epithelial to mesenchymal transition (EMT). It contains three highly conserved RNA recognition motifs (RRMs) in the absence of other clearly defined protein domains. Esrp1 itself is also alternatively spliced to produce multiple protein isoforms. Here we determined that two competing alternative 5' splice sites in exon 12 yield Esrp1 isoforms with differential nucleocytoplasmic localization. We carried out a detailed characterization of the Esrp1 peptide that is sufficient to confer nuclear localization. Furthermore, we identified splice variants encoding distinct nuclear and cytoplasmic isoforms of fusilli, the D. Melanogaster Esrp1 ortholog. Our observations demonstrate that the production of both nuclear and cytoplasmic Esrp1 isoforms through alternative splicing is phylogenetically conserved; strongly suggesting it is biologically significant. Thus, while previous studies have described extensive regulation by nuclear Esrp1 to promote epithelial specific splicing, it will be of great interest to study the contribution of cytoplasmic Esrp1 in maintenance of epithelial cell functions.
上皮剪接调节蛋白 1（Epithelial-Splicing-Regulatory-Protein 1，Esrp1）是一种细胞类型特异性 RNA 结合蛋白（RNA-binding protein，RBP），通过维持上皮细胞特性（包括屏障功能）对哺乳动物的发育至关重要。Esrp1 还在上皮细胞向间充质转化（epithelial-to-mesenchymal transition，EMT）过程中调节剪接。它在缺乏其他明确定义的蛋白结构域的情况下包含三个高度保守的 RNA 识别基序（RNA recognition motifs，RRMs）。Esrp1 自身也可以通过选择性剪接产生多种蛋白同工型。在这里，我们确定了外显子 12 中两个竞争的选择性 5' 剪接位点，产生了具有不同核质定位的 Esrp1 同工型。我们对足以赋予核定位的 Esrp1 肽进行了详细的特征描述。此外，我们鉴定了编码不同核和细胞质同工型的剪接变体 fusilli，这是 D. melanogaster Esrp1 的直系同源物。我们的观察结果表明，通过选择性剪接产生核质 Esrp1 同工型在进化上是保守的；这强烈表明它具有生物学意义。因此，尽管先前的研究已经描述了核 Esrp1 对促进上皮细胞特异性剪接的广泛调节，但研究细胞质 Esrp1 在维持上皮细胞功能中的作用将具有重要意义。
