Abstract 2148: Epigenetic Regulation in Scleroderma: High-Throughput Dna Methylation Profiling of Ssc Fibroblasts and Microvascular Endothelial Cells and the Central Role for Nos3 and Fli1 Epigenetic Repression in the Emergence of Ssc Cellular Phenotype
Authors:
Yongqing Wang, Bashar Kahaleh. University of Toledo, Toledo, OH
Background:
It has become clear in recent years that alterations in the non-coding regions of genomic DNA via methylation of cytosine nucleotides (epigenetic changes) can have profound effects on gene expression. These mechanisms might be particularly important in determining cell lineage differentiation and gene expression of particular pathways. Epigenetic repression of several genes responsible for uncontrolled extracellular matrix (FLI1 and NOS3) has previously been demonstrated. This study examines whether epigenetic changes might be implicated in the dysfunctional state of microvascular endothelial cells (MVEC) and fibroblasts in scleroderma patients.
Methods:
Genome-wide changes of DNA methylation in dermal fibroblasts and MVEC from scleroderma patients and controls were examined using differential display microarray technology. A second iteration of more restricted microarray experiments were performed to examine cardiovascular and extracellular matrix gene expression in these cells in greater detail. Finally, FLI1 and NOS3 expression was knocked down via siRNA trasfection of normal MVEC and fibrobalsts.
Results:
Over 5000 distinct genomic regions in cells derived from scleroderma patients (both MVEC and fibroblsts) were hypermethylated; interestingly, the corresponding transcribed regions were noted to be underexpressed. Focused miroarray studies of MVEC revealed increased proinflammatory, promitogenic, and vasospastic gene expression, all processes thought to arise from decreased NOS3 expression in these cells. This was confirmed by NOS3 knock-down in normal MVECs. Scleroderma fibroblasts exhibited a myofibroblast expression pattern, confirmed by siRNA knock-down experiments as well.
Editorial Comment
This study shows that entire programs of gene expression and regulation that confer pathogenic potential to the cell types dysregulated in scleroderma can arise via epigenetic repression of only a few genes. This leads to the exciting prospect that targeting the DNA methylation machinery to increase gene expression of scleroderma phenotype repressor genes like FLI1 might one day lead to more specific and disease-altering therapy for this complex and devastating disease.
