Assessment of transcript isoforms in Esrp1Triaka versus wild-type primary colonic epithelial cells

Alternative mRNA splicing is a process to increase the biodiversity of proteins that occurs in the majority of higher eukaryotic pre-mRNA. Altered mRNA splicing has been associated with several human diseases. Epithelial splicing regulatory protein 1 (ESRP1) was identified in a cDNA expression screen for factors promoting the epithelial pattern of FGFR2 splicing. ESRP1 was also found to regulate the alternative splicing of CD44 and other genes. Esrp1 is epithelial cell-restricted and is highly expressed in the murine large intestine. Here, we used a mouse mutant of Esrp1 called Triaka to investigate the function of ESRP1 protein in the intestine. Triaka mice are described in details under the following link: https://mutagenetix.utsouthwestern.edu/phenotypic/phenotypic_rec.cfm?pk=354. We first performed in vitro experiments using an exon trap vector based on luciferase expression, which indicated that the Esrp1Triaka allele leads to reduced mRNA splicing activity of the ESRP1 protein. In addition, RNA sequencing analysis showed altered patterns of transcript isoforms in Esrp1Triaka versus wild-type primary colonic epithelial cells. This was associated with impaired intestinal barrier integrity during homeostasis, increased susceptibility to experimental colitis and reduced colonic epithelial wound-healing capacity in Triaka mice. Together, these data indicate a central role of ESRP1 for intestinal barrier integrity.