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[log in to unmask]" type="cite">Thesis Defense Announcement
To:  The George Mason University Community


Candidate: John R. Grimsley
Program: Master of Science in Biology

Date:   Friday July 22, 2011
Time:   11:00 a.m.
Place:  George Mason University, Prince William campus
	     Bull Run Hall, Room 246
 
Thesis Chair:  Dr. Geraldine Grant

Title: "The Role of Krüppel Like Factor 4 in Idiopathic Pulmonary Fibrosis"

  

A copy of the thesis is on reserve in the Johnson Center Library, Fairfax campus.  The thesis will not be read at the meeting, but should be read in advance.

All members of the George Mason University community are invited to attend.

ABSTRACT:

Idiopathic Pulmonary Fibrosis (IPF) is a fatal interstitial lung disease (ILD) with no known cause and characterized by a progressive build up fibrotic tissue in the diseased lung.  Krüppel-Like Factor 4 (KLF4), a transcription factor with key roles in the cell cycle, cellular differentiation and development, was found to be over-expressed in primary IPF fibroblasts.  In this study we sought to investigate the potential role of KLF4 in IPF by investigating the effect of its over-expression on fibroblast differentiation and proliferation status in the normal human pulmonary fibroblasts cell line, MRC5.  In addition, we investigated the localization of KLF4 in vivo using normal and IPF tissue (LTRC). The in vivo localization of KLF4 in IPF and normal tissue was confirmed  by double-Immunohistochemistry (IHC) in combination with either alpha-SMA or PCNA (Abcam).  KLF4 over-expression in MRC5 cells was achieved using a doxycycline inducible lentiviral system (Addgene) and confirmed by quantitative real time PCR (Q-RTPCR) and western blot. The effect of KLF4 over-expression on markers of proliferation and activation was monitored by Q-RTPCR.  Localization of KLF4 in the IPF lung was observed on the perimeter of the fibroblastic foci and in the parenchyma in areas of advanced fibrosis, however, absent with in the fibrotic foci.  Co-localization of KLF4 and PCNA was observed, however, alpha-SMA and KLF4 were not observed to co-localize.  Following KLF4 induction in vitro a 6-fold increase in KLF4 mRNA and a 3-fold increase in protein were observed.   A decrease in alpha-SMA expression (2-fold) at both the gene and protein level was detected in addition to an increase in collagen 1A1 (3-fold) mRNA.  A decrease in all proliferation markers selected: PCNA, cyclin D1 and p21was observed, in addition to p53.  The in vivo distribution of KLF4, suggests may be involved in the advancement of  fibrosis and expansion of the foci.  In vitro over-expression studies in MRC5 cells revealed a profoundly negative affected on the cell cycle which appears to be in contrast of IPF, however, in keeping with KLF4’s dual roles of tumor suppressor and tumor promoter.  Of particular interest was KLF4 over-expression resulted in an increase in collagen production, the main ECM component of IPF.  KLF4 operated in a strongly context dependant manner, and IPF is a particularly context driven disease where the ECM acts almost as another pathogenic entity.  Therefore, while direct comparison between in vivo IPF fibroblasts and in vitro MRC5 cells cannot be made, these data indicates a potential role for KLF4 in the pathogenesis of IPF.  Further characterizations of this role through experimentation in primary adult IPF fibroblasts are warranted.

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