PROJECT SUMMARY/ABSTRACT African Americans (AA) and European Americans (EA) have a similar prevalence of gastro-esophageal reflux disease (GERD). Nonetheless, when compared to EA, AA show a lower incidence of esophagus damage, metaplasia, and esophageal adenocarcinoma. Population genetics and molecular studies have implicated specific genes for these differences in human tissue; however, a lack of racially diverse human esophagus models hinders further investigation into the mechanisms and potential treatment options. We developed an ancestrally diverse stem cell/organoid biobank of human esophagus and a high-content, image-based screening assay to interrogate bile-acid injury response. Results showed that AA esophageal cells responded significantly differently than EA-derived cells, mirroring tissue profiling and clinical findings. Furthermore, we have previously reported that a key enzyme, glutathione-transferase theta-2 (GSTT2), is responsible for inactivating reactive oxygen species, thus reducing DNA damage, and is highly expressed in the AA esophagus. Utilizing the ancestrally diverse stem cell model, we show key associations of GSTT2 low levels with higher injury, consistent with primary human tissue response to injury. However, a direct role of GSTT2 in this response and mechanism/drugs to maintain epithelial homeostasis and fitness to esophageal cells remains to be elucidated. Hypothesis: Esophageal tissue from African Americans respond differently to gastric acid/bile injury due to higher expression of detoxifying enzyme GSTT2, and compounds that can stabilize GSTT2 will protect cells against injury. The three specific aims to be investigated in this proposal will involve primary tissue and stem cell-derived in vitro cultures to validate the molecular profiles and differences in injury response between EA and AA cells at the single-cell level (Aim 1), with genetic manipulation of GSTT2 to determine direct mediation of protection against injury (Aim 2), and a high-throughput unbiased characterization of injury response coupled with a drug screen to determine compounds that will inhibit bile/acids injury (Aim 3). Dr. Ferrer-Torres’ primary research goals in the K99.R00 program is to develop high throughput techniques that will allow her to study ancestrally diverse populations and their response to injury. Therefore, the K99 phase has been planned to train in stem cell genetic modifications and high-content phenotypic-based drug discovery. For this mentored phase, Dr. Ferrer-Torres will work with Dr. Jason Spence and co-mentor by Dr. Jonathan Sexton. The mentored K99 program has been designed for Dr. Ferrer-Torres’ gain expertise in these areas. In addition, Dr. Jules Lin and Dr. Marcia Cruz-Correa will serve as advisory postdoctoral committee members and advisors for clinical immersions. This will be carried out utilizing the exceptional resources available at the University of Michigan. This will impulse Dr. Ferrer-Torres’ goals and hel...