LRIG1 Localization within the Colonic Crypt of Lrig3 Double Null Mice
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Date
2017
Authors
Taylor, Ainsley Lorraine
Journal Title
Journal ISSN
Volume Title
Publisher
University of Oregon
Abstract
Leucine rich repeats and immunoglobulin-like domains protein 1 (LRIG1) is a transmembrane protein that negatively regulates intestinal epidermal growth factor receptors (EGFRs) on the cell surface. This evidence suggests that LRIG1 suppresses cell growth and decreases the rate of cellular division within the intestine. Indeed, colonic tumorigenesis is observed in Lrig1-/- mice, definitively proving that LRIG1 is an intestinal tumor suppressor protein necessary for tissue homeostasis. Leucine rich repeats and immunoglobulin-like domains protein 3 (LRIG3) localization and functionality are fairly unknown. However, LRIG3 shares many morphological characteristics of LRIG1, which suggests LRIG3 may have similar localization and functionality as LRIG1. Indeed, current studies support this hypothesis, leading this paper to suggest LRIG3 may act as a redundant pathway for tumor suppression for LRIG1 within the colon. As such, this study analyzes shifts in colonic crypt LRIG1 localization in the absence of Lrig3. An upward trend in LRIG1-expressing cells is observed in the colonic crypts of Lrig3-/- mice, suggesting that Lrig3 product may restrict the upward migration of LRIG1. A concurrent decrease in Ki67/LRIG1 co-positive cells within these colonic crypts supports the observation that LRIG1 levels increase in absence of Lrig3 product. Therefore, this study suggests that LRIG3 may be localized above LRIG1 within the colonic crypt, and that absence of LRIG3 causes LRIG1 to extend its localization, possibly in order to act as a tumor suppressor in cells that would normally possess the redundant tumor suppressor LRIG3.
Description
46 pages. A thesis presented to the Department of Biology and the Department of Chemistry and Biochemistry and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, Spring 2017
Keywords
Colon, LRIG1, LRIG3, Ki67, Tumor suppressor, Stem cell