Novel actions of tissue-type plasminogen activator in chronic kidney disease.
Tissue-type plasminogen activator (tPA) is traditionally viewed as a simple serine protease whose main function is to convert plasminogen into biologically active plasmin. As a protease, tPA plays a crucial role in regulating blood fibrinolysis, in maintaining the homeostasis of extracellular matrix and in modulating the post-translational activation of growth factors. However, emerging evidence indicates that tPA also functions as a cytokine that transmits its signal across the cell membrane, initiates a diverse array of intracellular signaling, and dictates gene expression in the nuclei. tPA binds to the cell membrane LDL receptor-related protein 1 (LRP-1), triggers its tyrosine phosphorylation. As a cytokine, tPA plays a pivotal role in the pathogenesis of renal interstitial fibrosis through diverse mechanisms. It facilitates tubular epithelial to mesenchymal transition, potentiates myofibroblast activation, and protects renal interstitial fibroblasts/myofibroblasts from apoptosis. Together, growing evidence has implicated tPA as a fibrogenic cytokine that promotes the progression of kidney diseases. These new findings have radically changed our conception of tPA in renal fibrogenesis and represent a paradigm shift towards uncovering its cytokine function.
Hu
Kebin
K
Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA.
Mars
Wendy M
WM
Liu
Youhua
Y
D016207:Cytokines / Q000502:physiology; D005109:Extracellular Matrix / Q000502:physiology; D005355:Fibrosis; D006801:Humans; D007668:Kidney / Q000473:pathology; D007674:Kidney Diseases / Q000235:genetics*; D007676:Kidney Failure, Chronic / Q000235:genetics / Q000503:physiopathology*; D010960:Plasminogen Activators / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics; D015398:Signal Transduction; D010959:Tissue Plasminogen Activator / Q000502:physiology*
D016207:Cytokines; D012333:RNA, Messenger; D010960:Plasminogen Activators; D010959:Tissue Plasminogen Activator