title: Plasminogen kringle 5 induces endothelial cell apoptosis by triggering a voltage-dependent anion channel 1 (VDAC1) positive feedback loop.
abstract: Human plasminogen kringle 5 (K5) is known to display its potent anti-angiogenesis effect through inducing endothelial cell (EC) apoptosis, and the voltage-dependent anion channel 1 (VDAC1) has been identified as a receptor of K5. However, the exact role and underlying mechanisms of VDAC1 in K5-induced EC apoptosis remain elusive. In the current study, we showed that K5 increased the protein level of VDAC1, which initiated the mitochondrial apoptosis pathway of ECs. Our findings also showed that K5 inhibited the ubiquitin-dependent degradation of VDAC1 by promoting the phosphorylation of VDAC1, possibly at Ser-12 and Thr-107. The phosphorylated VDAC1 was attenuated by the AKT agonist, glycogen synthase kinase (GSK) 3β inhibitor, and siRNA, suggesting that K5 increased VDAC1 phosphorylation via the AKT-GSK3β pathway. Furthermore, K5 promoted cell surface translocation of VDAC1, and binding between K5 and VDAC1 was observed on the plasma membrane. HKI protein blocked the impact of K5 on the AKT-GSK3β pathway by competitively inhibiting the interaction of K5 and cell surface VDAC1. Moreover, K5-induced EC apoptosis was suppressed by VDAC1 antibody. These data show for the first time that K5-induced EC apoptosis is mediated by the positive feedback loop of "VDAC1-AKT-GSK3β-VDAC1," which may provide new perspectives on the mechanisms of K5-induced apoptosis.
authors.affiliation: From the Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, the Department of Reproductive Medicine Center, Key Laboratory for Reproductive Medicine of Guangdong Province, Third Affiliated Hospital of Guangzhou Medical University, 63 Duobao Road, Guangzhou 510150.
authors.forename: Lei
authors.initials: L
authors.lastname: Li
authors.affiliation: the Laboratory Center of Guangdong NO.2 Provincial People's Hospital, Guangzhou 510317.
authors.forename: Ya-Chao
authors.initials: YC
authors.lastname: Yao
authors.affiliation: the Department of Laboratory, Guangzhou Women and Children's Medical Center, Guangzhou 510623.
authors.forename: Xiao-Qiong
authors.initials: XQ
authors.lastname: Gu
authors.affiliation: From the Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080.
authors.forename: Di
authors.initials: D
authors.lastname: Che
authors.affiliation: From the Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080.
authors.forename: Cai-Qi
authors.initials: CQ
authors.lastname: Ma
authors.affiliation: From the Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080.
authors.forename: Zhi-Yu
authors.initials: ZY
authors.lastname: Dai
authors.affiliation: From the Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080.
authors.forename: Cen
authors.initials: C
authors.lastname: Li
authors.affiliation: From the Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080.
authors.forename: Ti
authors.initials: T
authors.lastname: Zhou
authors.affiliation: From the Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080.
authors.forename: Wei-Bin
authors.initials: WB
authors.lastname: Cai
authors.affiliation: From the Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080.
authors.forename: Zhong-Han
authors.initials: ZH
authors.lastname: Yang
authors.affiliation: From the Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, the China Key Laboratory of Tropical Disease Control, Sun Yat-sen University, Ministry of Education, Guangzhou 510080, and yangxia@mail.sysu.edu.cn.
authors.forename: Xia
authors.initials: X
authors.lastname: Yang
authors.affiliation: From the Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, the Key Laboratory of Functional Molecules from Marine Microorganisms, Sun Yat-sen University, Department of Education of Guangdong Province, Guangzhou 510080, China gaogq@mail.sysu.edu.cn.
authors.forename: Guo-Quan
authors.initials: GQ
authors.lastname: Gao
mesh_terms: D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D015153:Blotting, Western; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D025461:Feedback, Physiological / Q000187:drug effects; D038362:Glycogen Synthase Kinase 3 / Q000235:genetics / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D057809:HEK293 Cells; D061307:Human Umbilical Vein Endothelial Cells / Q000378:metabolism*; D006801:Humans; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D010446:Peptide Fragments / Q000235:genetics / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D010958:Plasminogen / Q000235:genetics / Q000494:pharmacology*; D011485:Protein Binding; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D034622:RNA Interference; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D025801:Ubiquitin / Q000378:metabolism; D050995:Voltage-Dependent Anion Channel 1 / Q000235:genetics / Q000378:metabolism*
chemical_list: D010446:Peptide Fragments; D025801:Ubiquitin; C494762:VDAC1 protein, human; C491499:plasminogen kringle 5; D010958:Plasminogen; D050995:Voltage-Dependent Anion Channel 1; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3; D020169:Caspases
keywords: Apoptosis; Bax; Cell Biology; Cell Signaling; Cell Surface Receptor; Cellular Regulation; Glycogen Synthase Kinase 3 (GSK-3); Molecular Cell Biology; PI 3-Kinase (PI3K); Phosphorylation