Gut Instincts

I have long been interested in biological processes, and a diagnosis of gluten intolerance in my freshman year sparked a particular curiosity about the digestive system.  When I decided I wanted to participate in undergraduate research, I sought a lab group whose research pursuits aligned with my own interests and was thrilled to discover the Lund Lab’s focus on gastrointestinal health and disease.  Now a senior, I have been working in Dr. P. Kay Lund’s Cell and Molecular Physiology laboratory since the beginning of my junior year at UNC.

In my first year of research I learned my way around the lab, assisting with a number of projects spearheaded by graduate students and postdocs.  During the spring semester, I realized that I wanted to take ownership of an independent project.  With the help of Dr. Lund, my graduate mentor Amanda Mah, and two other graduate students, I outlined a project for the summer that could eventually develop into honors thesis work.

My research evaluates the effects of high-fat diet on the intestine.  The study of GI growth, health, and disease is relevant to everyone because all people need proper digestive function to remain healthy.  Studies on the role of high-fat diet hold particular importance for local citizens.  Western diets are typically low in fiber and high in fat compared to other global diets, and the high fat content is exaggerated in many southern states such as North Carolina.  Consumption of fats and accumulation of excess body weight are known risk factors for diabetes and colorectal cancer development.  Figuring out the mechanisms by which fats adversely affect fitness is essential to the development of health interventions.

I use a number of laboratory techniques for collecting data.  Cell populations can be distinguished by their expression of various genes, so I am using fluorescent microscopy to quantify changes in cell populations.  Preliminary results reveal an increase in intestinal epithelial stem cells (IESC).  IESC are essential to the proper maintenance of the intestine, but an excess may promote the dysregulated cell growth characteristic of tumors.

Histology, or the microscopic study of tissues, is central to physiology studies.  Villi are the finger-like projections in the intestine used for nutrient absorption, and crypts lie at the base of villi housing IESC.  As it turns out, mice on high-fat diet (HFD) have taller villi in the proximal (beginning) part of their intestine than mice on normal diets.  Most likely, this occurs because more surface area is needed to absorb an increased amount of fats entering the intestine.  I expected to see an increase in crypt depth to accommodate an increased IESC population, but surprisingly no such difference is observed.

Working on the above components of the project has translated into many hours looking through microscopes!  Thankfully, it’s one of my favorite parts of lab work because it means concrete visualization of results.  I am also looking forward to working on more of the molecular components of the project.  In the coming months, I will assess the expression of insulin-like growth factor 1 receptor (IGF1R) in sorted cell populations.  IGF1R is a transmembrane protein that mediates the signal from its preferred ligand, IGF1, to increase cell proliferation and decrease programmed cell death.  An amplification of IGF1R expression might contribute to inappropriate IESC survival or proliferation and potential tumor formation.

Hannah is a Senior Chemistry major. She participated in the Summer Undergraduate Research Fellowship (SURF) program during the summer of 2011. If you have any questions or comments, feel free to post on the discussion board below.