Investigation of the role of DNA Methyltransferases in Autophagy Gene Expression and Function in Idiopathic Pulmonary Fibrosis (IPF)

Idiopathic pulmonary fibrosis (IPF) is characterized by a significant increase in collagen deposits in lung extracellular matrix (ECM) compared to non-IPF patients. Excessive collagen deposition is essential to the pathology of IPF and affects the fibrotic response to injury in lung tissue. Collagen turnover is regulated by autophagy, an intracellular mechanism that involves lysosomal degradation of unnecessary or dysfunctional cell components. It has been reported that autophagy is unsuccessful despite pathway activation in lungs of IPF patients. Previous work demonstrated that combination treatment of IPF cell lines with 5’-aza-2’-deoxycytidine, a DNA methylatransferase inhibitor, and rapamycin, an mTOR inhibitor, restored expression of key autophagy-regulating genes through decreased promoter CpG island methylation. Using primary lung fibroblasts from IPF patients and IPF fibroblast cell lines, we performed knockdown studies of each DNMT-1, 3A, and 3B mRNAs. Initial results show a marked reduction of DNMT-1 mRNA (84% reduction in both normal and severe IPF fibroblasts), DNMT-3A mRNA (68% reduction in normal fibroblasts relative to 83% in severe fibroblasts), and DNMT-3B mRNA (42% reduction in normal fibroblasts compared to 49% in severe IPF fibroblasts). Interestingly, as a result, when comparing expression of the 3 key autophagy-regulating genes BECN1, ATG5, and ATG12, it was targeting of DNMT-3B, and not DNMT-1 as hypothesized, that increased expression of these autophagy genes. This data suggests that DNMT-3B plays a regulatory role in restoring autophagy to IPF fibroblasts. In order to verify these data, we are currently investigating autophagy function in normal and IPF fibroblasts after siRNA targeting of DNMTs. Understanding the relationship between the functional responsibilities between DNA methylation moieties like DNMTs and histone deacetylases (HDACs), and their regulation of autophagy genes and function could identify new therapeutic targets for patients with IPF.Undergraduate Research Scholarship (OSU)No embargoAcademic Major: Microbiolog