Identifier

etd-012915-110129

Abstract

Work in our lab has resulted in the development of a novel approach to creating a more developmentally plastic human dermal fibroblast (hDF) phenotype that allows for the study of molecular mechanisms involved in cell-fate conversion. Culturing hDF under defined culture conditions (5% O2 and supplementation with fibroblast growth factor FGF2) induces induced the regeneration competent (iRC) phenotype that is characterized by stem cell gene expression, and increased life-span in vitro. The work presented in this thesis further characterizes the system, and describes an overall shift in extracellular matrix and adhesion molecules in human dermal fibroblasts (hDF) undergoing the transition to a more developmentally plastic phenotype (iRC). This work suggests that we create the initiation phase of Mesenchymal-to-Epithelial Transition (MET) during conversion to the iRC phenotype. This transition is marked by loss of integrin alpha-11 (α11) and its binding partner Collagen-I (COL-I). Moreover, we describe the mechanism for the down-regulation of α11 that is mediated by FGF2 activation of ERK1/2 through systematic investigation of several potential molecular mechanisms. The body of work presented here shows that the ERK 1/2 mediated down-regulation of α11 is independent of activation of TGF-β1-mediated regulation of α11. In addition to down-regulation of α11, an overall shift in the transcript levels of other adhesion molecules is observed, which demonstrates that iRC are most likely transitioning their attachment to a laminin and fibronectin-based matrix. These results suggest that iRC may be producing a more “pro-regenerative matrixâ€�. We hypothesize that the changes in integrin expression profile and interaction with ECM serve as a feedback loop during the iRC phenotype shift. Our findings suggest that this “pro-regenerativeâ€� shift in attachment of iRC as well as the ERK 1/2 mediated down-regulation of α11 could be exploited in wound healing biology and fibrosis research. Manipulation of the dynamic relationship between TGF-β1 and FGF2 has the potential to reduce scar deposition. Further identification of molecular mechanisms controlling this phenotype conversion will allow development of strategies for in situ manipulation of wound healing outcomes.

Publisher

Worcester Polytechnic Institute

Degree Name

PhD

Department

Biology & Biotechnology

Project Type

Dissertation

Date Accepted

2015-01-29

Accessibility

Unrestricted

Subjects

ECM, hESC, ITGA11, FGF2

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