Defining the Role of Tight Junctions, Protein Kinase A, and Apoptosis in NEC

Background: NEC affects 5% of all hospitalized premature infants, and may be fatal. Bacteria are implicated in disease, and Cronobacter sakazakii (CS) has been identified as causing outbreaks of NEC. Loss of intestinal barrier integrity and epithelial cell death are associated with NEC. Tight junctions (TJ) are protein complexes that seal the epithelium, and effect cellular signaling pathways. Protein kinase A (PKA) has been found to affect TJ cell surface to nuclear signaling. We hypothesize that CS binds to the epithelium activating PKA increasing TJ permeability and epithelial apoptosis, resulting in intestinal barrier failure and NEC. Research Design and Methods: Using three different experimental systems; a cell line model, a rat pup model and human tissue we will test the effect of CS on intestinal epithelial TJ complexes and barrier function. Based on prior studies and preliminary data, our working hypothesis is that CS induces TJ disruption and cellular internalization of TJ proteins. We expect that TJ disruption and internalization will correlate with the degree of experimental NEC. We will determine the role of PKA in CS-mediated epithelial apoptosis using a pharmaceutical approach. To define the mechanism of TJ alteration and apoptosis, we will analyze differences in kinetics of TJ proteins distribution and PKA signaling in response to CS. Research environment: This project will be performed in an outstanding academic university under the supervision of experts in the field. Career development activities within the proposal include learning new scientific techniques, didactic coursework, and regular feedback from her advisory committee.