However, recent advances in three-dimensional culture methods and in vivo imaging have revealed that many cells behave quite differently in extracellular matrix PR-171 cell line (ECM) in vivo, including mode-switching from mesenchymal motility to an invasive, amoeboid phenotype involving dynamic membrane blebbing.15, 16 Aquaporins (AQPs) are integral membrane water channels that allow for rapid, bidirectional flux of water in response to local osmotic gradients.17 Whereas

the expression and function of AQPs have been extensively studied in secretion and absorption across epithelial barriers,18, 19 these proteins are also expressed in endothelia, where their role is less clearly understood. Endothelial motility and invasion are well recognized as prerequisites for angiogenesis,20 and we Wnt assay noted several features of AQPs suggesting that they may contribute to amoeboid invasion in liver angiogenesis and cirrhosis.

First, recent studies show that AQPs may influence cell motility and angiogenesis in general.21, 22 Second, AQPs localize to areas of focal plasma membrane shape change and protrusions.23 Third, AQPs can directly interact with signaling molecules relevant to cell motility in addition to numerous solute/ion transporters.23, 24 Lastly, recent genetic studies in patients with chronic hepatitis C have identified an AQP single-nucleotide polymorphism as part of a genetic signature identifying patients at risk for progression to cirrhosis.25 However, direct mechanistic evidence for AQP regulation of liver endothelial cell (LEC) invasion in the context of cirrhosis is lacking. Therefore, we sought to test the hypothesis that AQP-1 is involved in FGF-induced pathological angiogenesis during cirrhosis

and to gain relevant mechanistic insights into this process. The experimental results from the current study provide several novel pieces of information regarding the mechanisms controlling LEC invasion through ECM. The work also begins to develop a foundation for plausible anti-angiogenic therapies targeting water channels in the treatment of cirrhosis and portal hypertension. Numerous AQP inhibitors in development make this direction ideal for future human translation.26 AQP, aquaporin; CCL4, carbon tetrachloride; ECM, extracellular 上海皓元 matrix; FGF, fibroblast growth factor; HHSEC, human hepatic sinusoidal endothelial cells; IF, immunofluorescence; IHC, immunohistochemistry; LEC, liver endothelial cell; NAFLD, nonalcoholic fatty liver disease; RT-PCR, reverse transcription polymerase chain reaction; SE, standard error; SEM, scanning electron microscopy; siRNA, small interfering RNA; TSEC, transformed sinusoidal endothelial cells; VEGF, vascular endothelial growth factor; vWF, von Willebrand factor. Additional experimental details and references can be found in the Supporting materials.