Abstract
Clathrin-dependent endocytosis is believed to be involved in TGFbeta-stimulated cellular responses, but the subcellular locus at which TGFbeta induces signaling remains unclear. Here, we demonstrate that inhibitors of clathrin-dependent endocytosis, which are known to arrest the progression of endocytosis at coated-pit stages, inhibit internalization of cell-surface-bound TGFbeta and promote colocalization and accumulation of TbetaR-I and SARA at the plasma membrane. These inhibitors enhance TGFbeta-induced signaling and cellular responses (Smad2 phosphorylation/nuclear localization and expression of PAI-1). Dynasore, a newly identified inhibitor of dynamin GTPase activity, is one of the most potent inhibitors among those tested and, furthermore, is a potent enhancer of TGFbeta. Dynasore ameliorates atherosclerosis in the aortic endothelium of hypercholesterolemic ApoE-null mice by counteracting the suppressed TGFbeta responsiveness caused by the hypercholesterolemia, presumably acting through its effect on TGFbeta endocytosis and signaling in vascular cells.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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Animals
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Apolipoproteins E / genetics
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Apolipoproteins E / metabolism
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Cadaverine / analogs & derivatives
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Cadaverine / pharmacology
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Carrier Proteins / genetics
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Carrier Proteins / metabolism
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Cell Line
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Clathrin / metabolism*
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Endocytosis / drug effects
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Endocytosis / physiology*
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Enzyme Inhibitors / pharmacology
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Female
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GTP-Binding Proteins
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Hydrazones / pharmacology
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Mice
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Mice, Inbred C57BL
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Mice, Knockout
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Monensin / pharmacology
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Plasminogen Activator Inhibitor 1 / genetics
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Plasminogen Activator Inhibitor 1 / metabolism
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Protein Serine-Threonine Kinases / genetics
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Protein Serine-Threonine Kinases / metabolism
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Receptor, Transforming Growth Factor-beta Type I
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Receptors, Transforming Growth Factor beta / genetics
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Receptors, Transforming Growth Factor beta / metabolism
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Signal Transduction / drug effects
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Signal Transduction / physiology*
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Smad2 Protein / metabolism
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Transforming Growth Factor beta / metabolism*
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Triflupromazine / pharmacology
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beta-Cyclodextrins / pharmacology
Substances
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Apolipoproteins E
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Carrier Proteins
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Clathrin
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Enzyme Inhibitors
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Hydrazones
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N'-(3,4-dihydroxybenzylidene)-3-hydroxy-2-naphthahydrazide
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Plasminogen Activator Inhibitor 1
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Receptors, Transforming Growth Factor beta
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SARA protein, mouse
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Smad2 Protein
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Smad2 protein, mouse
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Transforming Growth Factor beta
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beta-Cyclodextrins
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Monensin
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Protein Serine-Threonine Kinases
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Receptor, Transforming Growth Factor-beta Type I
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GTP-Binding Proteins
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monodansylcadaverine
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betadex
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Cadaverine
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Triflupromazine