Alternative splicing regulates distinct subcellular localization of Epithelial splicing regulatory protein 1 (Esrp1) isoforms

Yueqin Yang,Russ P Carstens

doi:10.1038/s41598-017-03180-3

Yueqin Yang, Russ P Carstens

Open Access

https://doi.org/10.1038/s41598-017-03180-3

Copy DOI

Journal: Scientific Reports	Publication Date: Jun 20, 2017
Citations: 21	License type: open-access

Affiliation: University of Pennsylvania

Abstract

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.

Highlights

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
Based upon examples of other splicing factors with nuclear and cytoplasmic isoforms generated through alternative splicing, we considered the possibility that different Esrp[1] splice isoforms might account for this differential localization
The alternative 5′ splice sites in Esrp[1] exon 12 consists of two identical 5′ splice site consensus sequences that are separated by 12 nucleotides (5-TGAAGTTACCAT-3), usage of which generates protein isoforms that differ by four amino acids “Cys-Lys-Leu-Pro” (CKLP) (Fig. 1a)

Summary

Introduction

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. Our observations demonstrate that the production of both nuclear and cytoplasmic Esrp[1] isoforms through alternative splicing is phylogenetically conserved; strongly suggesting it is biologically significant. RNA binding proteins (RBPs) play crucial roles at each step in RNA processing, including 5′ capping, splicing, polyadenylation, mRNA transport, localization, mRNA stability, and translation. The multifunctional roles of RBPs depend on the ability of a single gene to produce multiple isoforms with different nucleocytoplasmic localization through alternative splicing. Three splice isoforms of QKI with differential subcellular localization have been found to regulate multiple post-transcriptional processes, including splicing, mRNA localization, mRNA stability and protein translation[6,7,8,9]. Emerging evidence suggests that integrated post-transcriptional regulation by a specific RBP can function to shape biologically coherent post-transcriptional regulons[1]

Methods

Results

Conclusion