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2013 Reseach Abstract

Loss of Laminin γ3 Chain Affects Rates of Corneal Epithelial Cell Proliferation, Differentiation and Apoptosis

Investigators: Sarah Siu

Mentor: Mentor William J. Brunken, PhD

Purpose: Corneal diseases are often accompanied with, or caused by, changes in the molecular composition of its extracellular matrix (ECM). Laminins are the most abundant non-collagenous proteins of highly specialized extracellular matrices known as basement membranes (BM), and are necessary for BM formation. Laminins are comprised of α, β, and γ chains and have key roles in BM formation, cell cycle regulation, and cell migration. The purpose of this study was to examine the role of laminin γ3 chains in maintaining BM integrity and regulating epithelial cell behavior.

Methods: Corneas from mutant mice lacking Lamc3, Lamb2, or both genes (DKO) genes were compared to wild-type (WT) littermates. Immunofluorescence was used to assay cell differentiation, progenitor pool size and proliferation in sectioned or whole-mounted tissue preparations. Primary antibodies against Keratin-12, Keratin-14, and involucrin were used to assess cell differentiation; p63 and phospho-histone H3pSer28 (PH3pSer28) were used to assess progenitor pool size and proliferative activity, respectively. Data were quantified and compared for statistical significance where appropriate.

Results: Collectively, the work carried out by other lab members and myself show that gross differentiation of corneal keratinocytes appeared unaffected in mutant mice vs. WT counterparts. However, numbers of mitotically active, PH3pSer28+ progenitor cells were significantly decreased (p < .01) at P10 in Lamc3-/- vs. WT mice, and at P20 in DKO vs. WT mice. A disrupted intracellular distribution of p63 was also observed in Lamc3-/- mice vs. WT counterparts at P20.

Conclusion: To date, results indicate that γ3 chain-containing laminins are important components of the progenitor pool/stem cell niche, where they likely regulate progenitor pool size, as well as their proliferative capacity. Ongoing studies are directed toward assessing rates of cell death and p63 trafficking, while future studies will evaluate the role of laminins in corneal wound healing, specifically during re-epithelialization.

Updated on July 7, 2014.