Discipline: Biological Sciences
Subcategory: Cell and Molecular Biology
Ebony Hargrove-Wiley - Tuskegee University
Co-Author(s): Jessica Preston and Anne Powell, University of Oregon, Eugene, OR
Ulcerative colitis is a type of Inflammatory Bowel Disease (IBD), which is believed to be caused by a number of factors and lacks an enduring treatment. Colitis is characterized by recurrent inflammation and damage to the epithelial lining. The harsh, everyday environment of the intestine requires stem cells to maintain homeostasis. These cells exhibit both self-renewal and the ability to develop into all tissue subtypes, and they are able to regenerate damaged cells of the intestine. For this reason, we expect that stem cells should play a vital role in the repair of the colon following inflammation and injury. However, very little is currently known about the mechanisms behind stem cell repair of the colonic injuries. Models of colitis and IBD have been recreated in mice. In one common technique, animals are induced with an altered carbohydrate, dextran sulphate sodium (DSS), that penetrates the cells to cause inflammation that resembles human IBD. The DSS model is simple to induce with immediate, controllable onset. Preliminary investigations focusing on a particular group of stem cells marked by Lrig1 proteins, have shown that these cells initiate repair following injury from DSS. DSS-induced colitis should stimulate of stem cells located at the point of injury. In this study, Lrig1+ stem cell stimulation and proliferation will be quantified post-exposure to DSS (during the recovery phase) using lineage tracing and immunofluorescence. Using immunofluorescence, we will label targeted antigens to detect the presence of cellular components. On the other hand, lineage tracing involves the expression of a fluorescent protein under control of a cell-specific promoter (in this case, Lrig1). This technique labels cells expressing the promoter and their progeny. Activation of the LRIG1 stem cells amplified upon recovery of DSS treatment. Lineage tracing identified daughter cells with increased localization on the lateral sides of the intestinal crypt. Immunofluorescence showed an overlap of Lrig1 protein and Lrig1 daughter cells via Lrig1-driven lineage tracing of genes in the stem cells. Progeny located on the lateral sides were 31% less likely of LRIG1+ coexpression, suggesting differentiation. These results uncover the activity of intestinal stem cells during recovery and support a proficient involvement of LRIG1 stem cells in crypt restoration. Further investigation of these LRIG1 stem cells and their progeny could aid in better-quality therapeutic interventions for patients suffering from ulcerative colitis.
Funder Acknowledgement(s): NSF REU Site Program in Molecular Biosciences (NSF DBI/BIO 1460735).
Faculty Advisor: Jessica Preston, Anne Powell, firstname.lastname@example.org
Role: My contribution to the research project was the mounting of the model tissue to slides. Once the slides were fixed, I was able to antibody stain the tissue for fluorescent microscopy analysis. I conducted cells counts which serve as the data for the calculated graphs.