The effect of valproic acid on notch signaling in Danio rerio intestinal cell differentiation

Abstract

Inflammatory bowel disease (IBD) is a classification of chronic remittent immune disorders affecting approximately 1.4 million people in the United States between the ages of 15 and 40. It is thought to be caused by an interaction between genetic predisposition and environmental factors, an exact mechanism explaining the onset of IBD remains unclear. Recent studies indicate a reduced number of mucus secreting cells is typical in affected individuals, and that the differentiation of intestinal cell types into either absorptive or secretory is governed by a Notch signaling pathway. There remain gaps in knowledge of how this pathway is activated or inhibited in people with chronic IBD. The purpose of this study was to induce the Notch pathway in zebrafish. We hypothesize that a corollary shift in the expression of secretory versus absorptive cell types in the gut would be observed in fish treated with valproic acid (VPA). Studies showed that VPA, a compound frequently used in the treatment of neurological disorders, activates Notch in the regulation of neuronal cells. A dosage curve was generated and the optimal concentration of VPA to administer that appeared to have an effect, without overdosing the zebrafish was determined to be 500 and 1000 µM. Following VPA treatment, brain and intestinal tissue was extracted and an RT‐PCR was run. A 30% increase in the expression of the Notch receptor was observed in brain tissue indicating VPA maybe activating Notch signaling. Preliminary results indicate that zebrafish are a viable model to study Notch signaling in the intestine. Future experiments will focus on intestinal RT‐PCR to confirm Notch receptor expression and western blot analysis will be conducted to observe any differences in the amount of secretory cells and enterocytes in the intestines following VPA treatment.