title: Globotriaosylceramide induces lysosomal degradation of endothelial KCa3.1 in fabry disease.
abstract: OBJECTIVE
  Globotriaosylceramide (Gb3) induces KCa3.1 downregulation in Fabry disease (FD). We investigated whether Gb3 induces KCa3.1 endocytosis and degradation.
  
  
  RESULTS
  KCa3.1, especially plasma membrane-localized KCa3.1, was downregulated in both Gb3-treated mouse aortic endothelial cells (MAECs) and human umbilical vein endothelial cells. Gb3-induced KCa3.1 downregulation was prevented by lysosomal inhibitors but not by a proteosomal inhibitor. Endoplasmic reticulum stress-inducing agents did not induce KCa3.1 downregulation. Gb3 upregulated the protein levels of early endosome antigen 1 and lysosomal-associated membrane protein 2 in MAECs. Compared with MAECs from age-matched wild-type mice, those from aged α-galactosidase A (Gla)-knockout mice, an animal model of FD, showed downregulated KCa3.1 expression and upregulated early endosome antigen 1 and lysosomal-associated membrane protein 2 expression. In contrast, no significant difference was found in early endosome antigen 1 and lysosomal-associated membrane protein 2 expression between young Gla-knockout and wild-type MAECs. In aged Gla-knockout MAECs, clathrin was translocated close to the cell border and clathrin knockdown recovered KCa3.1 expression. Rab5, an effector of early endosome antigen 1, was upregulated, and Rab5 knockdown restored KCa3.1 expression, the current, and endothelium-dependent relaxation.
  
  
  CONCLUSIONS
  -Gb3 accelerates the endocytosis and lysosomal degradation of endothelial KCa3.1 via a clathrin-dependent process, leading to endothelial dysfunction in FD.
authors.affiliation: From the Departments of Physiology (S.C., J.A.K., H.-Y.N., S.-E.C., S.P., S.H.S.) and Biochemistry (S.-C.J.), Medical School, Ewha Womans University, Seoul, Korea.
authors.forename: Shinkyu
authors.initials: S
authors.lastname: Choi
authors.forename: Ji Aee
authors.initials: JA
authors.lastname: Kim
authors.forename: Hye-Young
authors.initials: HY
authors.lastname: Na
authors.forename: Sung-Eun
authors.initials: SE
authors.lastname: Cho
authors.forename: Seonghee
authors.initials: S
authors.lastname: Park
authors.forename: Sung-Chul
authors.initials: SC
authors.lastname: Jung
authors.forename: Suk Hyo
authors.initials: SH
authors.lastname: Suh
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002966:Clathrin / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D004705:Endocytosis; D042783:Endothelial Cells / Q000201:enzymology*; D004730:Endothelium, Vascular / Q000201:enzymology* / Q000503:physiopathology; D000795:Fabry Disease / Q000201:enzymology* / Q000235:genetics / Q000503:physiopathology; D061307:Human Umbilical Vein Endothelial Cells / Q000201:enzymology; D006801:Humans; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels / Q000378:metabolism*; D052119:Lysosomal-Associated Membrane Protein 2 / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D021381:Protein Transport; D059748:Proteolysis; D034622:RNA Interference; D014162:Transfection; D014281:Trihexosylceramides / Q000378:metabolism*; D014664:Vasodilation; D033921:Vesicular Transport Proteins / Q000378:metabolism; D000519:alpha-Galactosidase / Q000235:genetics / Q000378:metabolism; D020696:rab5 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D002966:Clathrin; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels; C496923:KCNN4 protein, human; C496925:Kcnn4 protein, mouse; C497811:LAMP2 protein, human; D052119:Lysosomal-Associated Membrane Protein 2; D014281:Trihexosylceramides; D033921:Vesicular Transport Proteins; C093846:early endosome antigen 1; C018549:globotriaosylceramide; D000519:alpha-Galactosidase; D020696:rab5 GTP-Binding Proteins
keywords: Ca2+-activated K+ channels; Fabry disease; glycosphingolipids; protein transport