Poster abstracts
Poster number 69 submitted by Chetan Gomatam
Direct effects of mineralocorticoid receptor signaling on dystrophic skeletal muscle fibroblasts
Chetan K. Gomatam (Molecular, Cellular, and Developmental Biology Program, The Ohio State University), Swathy Krishna (Department of Physiology and Cell Biology, College of Medicine, The Ohio State University), Jeovanna Lowe (Department of Physiology and Cell Biology, College of Medicine, The Ohio State University), Christoph Lepper (Department of Physiology and Cell Biology, College of Medicine, The Ohio State University), Jill A. Rafael-Fortney (Department of Physiology and Cell Biology and Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University)
Abstract:
Duchenne muscular dystrophy (DMD) is an X-linked, fatal disease resulting from the loss of dystrophin that causes chronic striated muscle injury and gradual muscle degeneration, leading to destruction of muscle and eventual loss of life in the mid-twenties. Cycles of muscle degeneration and regeneration cause persistent injury, which leads to fibroblast overactivation. Fibroblasts are normally essential for temporarily stabilizing injury sites and for maintaining organ structure by depositing extracellular matrix (ECM) components. However, overactivated fibroblasts deposit excess amounts of ECM that replaces muscle tissue in DMD and causes pathogenic fibrosis. We have identified mineralocorticoid receptor (MR) antagonists as a potential therapy to alleviate fibrosis and inflammation in muscular dystrophies, and we have shown that MR signaling from other cell types in the muscle microenvironment indirectly affects fibroblasts. However, direct effects of MR signaling on fibroblasts and the role of MR in muscle fibroblasts are not known.
Using RNA sequencing on naïve wildtype fibroblasts treated in vitro with the MR agonist aldosterone, we have shown that direct changes in MR signaling lead to differential gene expression. Periostin, which is expressed in activated myofibroblasts, was the only myofibroblast gene that was increased by aldosterone. We have begun to explore the fibroblast response to direct MR signaling and the role of fibroblast-specific MR using in vitro assays testing key aspects of fibroblast function, including proliferation, collagen contraction, and migration. Aldosterone appears to repress proliferation in dystrophin deficient adult mdx fibroblasts, and neonatal mdx and wildtype fibroblasts are more proliferative than their adult counterparts regardless of genotype. Further in vitro assays combined with genetic approaches will be used to decipher whether MR signaling has direct effects on fibroblast activation and other aspects of fibroblast function such as ECM production, and whether MR signaling differs between muscle groups.
Keywords: Muscular dystrophy, Fibrosis, Mineralocorticoid receptor