Tag: Anne Zemper

Lrig3 is Required for Colonic Regeneration Following Acute Inflammatory Injury

Presenter: Kevin Mueller – Biology

Faculty Mentor(s): Anne Zemper, Janelle Stevenson

Session: (In-Person) Oral Panel—Daily Dose of Proteins

The mouse colon is a tightly regulated organ responsible for secreting mucus and absorbing water, which is carried out by colonic crypts; small U-shaped invaginations in the colon’s epithelial tissue. The excision of the protein Lrig3 has been characterized in homeostasis and is defined by more nuclei per crypt, increased mucosal area, and an expanded stem cell compartment consisting of more Lrig1+ cells per crypt. While we now understand that Lrig3 plays an important role in homeostasis, it is currently unknown what role Lrig3 might play in colon-based diseases. The disease we chose to test first was the mouse model of ulcerative colitis. Our lab treated two cohorts of mice, one Wild Type (WT) and one Lrig3-/-, with a 3% Dextran Sodium Sulfate (DSS) solution over 6 days to induce inflammation. Both cohorts were allowed to recover for 24 hours before analysis. We found Lrig3-/-mice are more susceptible to DSS treatment and lack the colonic regenerative capability seen in WT mice. We then performed immunohistochemistry, dye, and enzymatic-based analyses to examine the expression profiles of proteins associated with regeneration of the colonic epithelium. We observed a decrease in cells expressing the stem and progenitor marker Lrig1 in Lrig3-/- mice compared to WT (p<0.01) and a decrease in the total cell number per crypt (p<0.001), however there was no change in proliferation. These data suggest Lrig3 is required for epithelial regeneration in DSS- modeled ulcerative colitis.

Determining the Function of LRIG1 in Colon Cancer Cell Behavior

Presenter(s): TJ Ekstrom

Faculty Mentor(s): Anne Zemper & Kate Walsh

Poster 6

Session: Sciences

Regulation of the Epidermal Growth Factor Receptor (EGFR) signaling cascade is critical for cellular homeostasis. Disruption of EGFR control of cell migration and proliferation is seen in many types of cancer cells. The transmembrane protein, Leucine-rich repeats and immunoglobulin-like domains 1 (LRIG1) controls cellular growth via negative regulation of the ErbB family of receptor tyrosine kinases, including EGFR. LRIG1 functions as a tumor suppressor and its expression is often reduced in cancers. In vitro studies of LRIG1 expression could lead to new insights into its regulatory role in highly proliferative tissues like the colon. The colon is a dynamic organ where EGFR and its regulation by LRIG1 may be essential in maintaining homeostasis. The colonic cancer cell line Caco-2 will be used to overexpress LRIG1 and determine changes in EGFR signaling. To overexpress LRIG1, the cells were transfected using a constitutively expressed myc tagged LRIG1 plasmid and selected for using an antibiotic. A scratch assay was performed on cell lines to assess changes in cellular migration and proliferation behavior. An increase of LRIG1 protein in the transfected cells is expected to decrease migration and proliferation. The activity of proteins negatively regulated by LRIG1 within the EGFR signaling cascade including proteins such as pEGFR and pErk 1/2 will decrease as viewed by western blot analysis and immunocytochemistry. Successful manipulation of the Caco-2 cell line will create an in vitro tool to study LRIG1 and its correlation to colon homeostasis.