Idiopathic pulmonary fibrosis (IPF) is characterized by thickening and stiffness around the air sacs. Approved treatments like nintedanib and pirfenidone slow disease progression in IPF and often have tolerability issues. More research is needed to fully grasp the mechanisms behind abnormal cytoskeletal changes in lung cells, notably fibroblasts and epithelial cells, and their role in fibrosis progression. Previous studies suggest that myocardin expression and function, traditionally limited to smooth/cardiac development in physiology, become active in pathophysiological conditions like pleural fibrosis. Myocardin's role in liver and kidney fibrosis is known, but its involvement in IPF is unclear. To get more insights, we conducted mRNA sequencing, and the results revealed the downregulation of fifty-five candidate genes, including PAI-1, following myocardin knockdown. Upon TGF-β stimulation, PAI-1, FN-1, α-SMA, and collagen significantly increased, whereas myocardin knockdown decreased their expression as shown by qPCR and western blot. Colocalization analysis showed a higher extent of colocalization of PAI-1 with tubulin than actin across all conditions, suggesting its transportation on microtubules rather than microfilaments. Proximity Ligation Assay identified a reduction in PAI-1 and KIF5, a microtubule-associated motor protein, association post- myocardin knockdown, though TGF-β did not show a significant difference in PAI-1 and tubulin proximity. These results suggest that myocardin regulates the expression of PAI-1 and its association with microtubule-associated motor protein, KIF5, thus controlling the transportation and secretion of PAI-1 that contributes to the progression of IPF.

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Dr. Osamu Sato, Dr. Pierre Neuenschwander, Dr. Mitsuo Ikebe, Dr. Maolin Lu


Master of Science in Biotechnology