PINCH-1 promotes tubular epithelial-to-mesenchymal transition by interacting with integrin-linked kinase.
PINCH-1 is an adaptor protein that binds to the integrin-linked kinase (ILK), an intracellular serine/threonine protein kinase that plays a critical role in mediating tubular epithelial-to-mesenchymal transition (EMT). To determine whether PINCH-1 is also involved in the EMT process, we investigated its regulation and function during TGF-beta1-stimulated EMT. TGF-beta1 induced PINCH-1 mRNA and protein expression in human proximal tubular epithelial cells in a time-dependent fashion, an effect that was largely dependent on intracellular Smad signaling. Overexpression of PINCH-1 suppressed epithelial markers E-cadherin and ZO-1 and increased fibronectin expression and extracellular assembly, whereas knockdown of PINCH-1 via small interfering RNA reduced TGF-beta1-mediated fibronectin expression and partially restored E-cadherin. PINCH-1 formed a ternary complex with ILK at the focal adhesion sites of tubular epithelial cells. Treatment with an ILK inhibitor or disruption of the ILK/PINCH-1 interaction by overexpressing a dominant-negative N-terminal ankyrin domain of ILK resulted in reduced fibronectin deposition, indicating that the ability of PINCH-1 to stimulate EMT is ILK-dependent. In a mouse model of obstructive nephropathy, PINCH-1 expression increased in a time-dependent manner, suggesting that it may play a role in EMT and renal fibrosis in vivo. We conclude that PINCH-1, through its interaction with ILK, plays an important role in regulating TGF-beta1-mediated EMT and could be a potential future therapeutic target to prevent progression of renal disease.
Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA.
Yingjian
Y
Li
Chunsun
C
Dai
Chuanyue
C
Wu
Youhua
Y
Liu
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004847:Epithelial Cells / Q000166:cytology*; D005353:Fibronectins / Q000378:metabolism; D005355:Fibrosis; D022001:Focal Adhesions / Q000378:metabolism; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D007668:Kidney / Q000378:metabolism / Q000473:pathology; D007674:Kidney Diseases / Q000378:metabolism / Q000473:pathology; D007687:Kidney Tubules, Proximal / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D060588:LIM Domain Proteins; D008297:Male; D008565:Membrane Proteins; D008648:Mesoderm / Q000166:cytology*; D051379:Mice; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis; D034741:RNA, Small Interfering / Q000494:pharmacology; D015398:Signal Transduction; D051785:Smad Proteins / Q000378:metabolism; D013997:Time Factors; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology; D000099200:Scaffold Protein ILK
D048868:Adaptor Proteins, Signal Transducing; D004268:DNA-Binding Proteins; D005353:Fibronectins; D060588:LIM Domain Proteins; D008565:Membrane Proteins; D017346:Protein Serine-Threonine Kinases; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D051785:Smad Proteins; D053773:Transforming Growth Factor beta1; D000099200:Scaffold Protein ILK; C088088:LIMS1 protein, human