Transcriptional regulation of intestinal epithelial polarization and maturation of Oncorhynchus mykiss in vitro
The intestinal epithelium is crucial for nutrient absorption, immune defense, and barrier function in farmed fish. However, the molecular mechanisms underlying its development and maturation in salmonids remain poorly characterized, hindering our ability to address pervasive gut health challenges in aquaculture. This study leverages the RTgutGC cell line to establish the first integrated functional and transcriptomic model of intestinal epithelial maturation in rainbow trout (Oncorhynchus mykiss). We optimized in vitro culture conditions for the differentiation and polarization of rainbow trout enterocytes on permeable supports. At 28 days post-seeding (dps), a polarized epithelial barrier was generated with high transepithelial electrical resistance, low permeability, and well-defined apical specializations, including clusters of microvilli and primary cilia. Incubation times of 7 and 28 dps were selected to represent immature and mature epithelium, respectively. A comparative transcriptomic profile was then performed between the two conditions, differentially expressed genes (DEGs) were determined and a functional enrichment analysis was done. By integrating ultrastructural, functional, and transcriptomic data, this study established a framework for future mechanistic investigations into gut development and for designing targeted nutritional interventions to enhance intestinal health and resilience in farmed fish.