KIF5A is Responsible for Collagen Transport of Myofibroblasts during Pleural Fibrosis

Fibrosis is the production of extracellular matrix proteins in tissues and often proceeded by injuries. In pleural fibrosis excess collagen deposition occurs, which results in increased stiffness and thickening of pleura during tissue rearrangements. Myofibroblasts are responsible for oversecretion of collagen, however the molecular mechanism of transportation of procollagen containing vesicles for secretion is unknown. Here, we studied the role of kinesin on collagen-1 containing vesicle transportation in human pleural mesothelial cells (HPMCs). Among a number of cargo transporting kinesins, KIF5A was notably upregulated during TGF-β induced mesothelial-mesenchymal transition (MesoMT). Using superresolution structured illumination microscopy (SIM) and DUO-Link technique, we found KIF5A notably colocalizes with collagen-1 containing vesicles. KIF5A knock-down (KD) by specific siRNA significantly reduced collagen-1 secretion but not plasminogen activator inhibitor 1 (PAI-1). KIF5A KD notably attenuated TGF-β induced increase in collagen-1 localization at cell peripheries. Live cell imaging with GFP-KIF5A and mCherry-collagen-1 showed that KIF5A and collagen-1 containing vesicles moved together. Kymograph showed that these molecules continuously move with mean velocity of 0.56 μm/sec, suggesting that the movement is directional but not diffusion process. Moreover, KIF5A was notably upregulated along with collagen-1 and α-smooth muscle actin (α-SMA) (MesoMT marker) in thickening pleura of carbon-black bleomycin mouse model. All the results support that KIF5A is responsible for collagen transportation and secretion from HPMCs.