title: 7-Ketocholesterol-induced lysosomal dysfunction exacerbates vascular smooth muscle cell calcification via oxidative stress.
abstract: Vascular calcification is known to reduce the elasticity of aorta. Several studies have suggested that autophagy-lysosomal pathway (ALP) in vascular smooth muscle cells (VSMCs) is associated with vascular calcification. A major component of oxidized low-density lipoproteins, 7-ketocholesterol (7-KC), has been reported to promote inorganic phosphorus (Pi)-induced vascular calcification and induce ALP. The aim of this study was to unravel the relationship between ALP and the progression of calcification by 7-KC. Calcification of human VSMCs was induced by Pi stimulation in the presence or absence of 7-KC. FACS analysis showed that 7-KC-induced apoptosis at a high concentration (30 μM), but not at a low concentration (15 μM). Interestingly, 7-KC promoted calcification in VSMCs regardless of apoptosis. Immunoblotting and immunostaining showed that 7-KC inhibits not only the fusion of autophagosomes and lysosomes but also causes a swell of lysosomes with the reduction of cathepsin B and D. Moreover, lysosomal protease inhibitors exacerbated the apoptosis-independent calcification by 7-KC although inhibition of autophagosome formation by Atg5 siRNA did not. Finally, the 7-KC-induced progression of calcification was alleviated by the treatment with antioxidant. Taken together, our data showed that 7-KC promotes VSMC calcification through lysosomal-dysfunction-dependent oxidative stress.
authors.affiliation: Department of Tissue Regeneration, Hoshi University School of Pharmacy and Pharmaceutical Sciences, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 142-8501, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Sudo
authors.affiliation: Department of Analytical Pathophysiology, Hoshi University School of Pharmacy and Pharmaceutical Sciences, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 142-8501, Japan.
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Sato
authors.affiliation: Department of Tissue Regeneration, Hoshi University School of Pharmacy and Pharmaceutical Sciences, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 142-8501, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Azechi
authors.affiliation: Department of Tissue Regeneration, Hoshi University School of Pharmacy and Pharmaceutical Sciences, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 142-8501, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Wachi
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D002401:Cathepsin B / Q000378:metabolism; D002402:Cathepsin D / Q000378:metabolism; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007653:Ketocholesterols / Q000494:pharmacology*; D008247:Lysosomes / Q000187:drug effects* / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects*; D010758:Phosphorus / Q000494:pharmacology; D061205:Vascular Calcification / Q000139:chemically induced* / Q000378:metabolism
chemical_list: D007653:Ketocholesterols; D010758:Phosphorus; C533912:CTSB protein, human; D002401:Cathepsin B; C533922:CTSD protein, human; D002402:Cathepsin D; C003001:7-ketocholesterol