Globotriaosylceramide induces lysosomal degradation of endothelial K _Ca3.1 in fabry disease

OBJECTIVE - Globotriaosylceramide (Gb3) induces K_Ca3.1 downregulation in Fabry disease (FD). We investigated whether Gb3 induces K _Ca3.1 endocytosis and degradation. APPROACH AND RESULTS - K _Ca3.1, especially plasma membrane-localized K_Ca3.1, was downregulated in both Gb3-treated mouse aortic endothelial cells (MAECs) and human umbilical vein endothelial cells. Gb3-induced K_Ca3.1 downregulation was prevented by lysosomal inhibitors but not by a proteosomal inhibitor. Endoplasmic reticulum stress-inducing agents did not induce K _Ca3.1 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 K_Ca3.1 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 K_Ca3.1 expression. Rab5, an effector of early endosome antigen 1, was upregulated, and Rab5 knockdown restored K_Ca3.1 expression, the current, and endothelium-dependent relaxation. CONCLUSIONS: - Gb3 accelerates the endocytosis and lysosomal degradation of endothelial K_Ca3.1 via a clathrin-dependent process, leading to endothelial dysfunction in FD.