title: Extracellular regulated protein kinases play a key role via bone morphogenetic protein 4 in high phosphate-induced endothelial cell apoptosis.
abstract: OBJECTIVE
  Hyperphosphatemia is an independent risk factor of cardiovascular events in the patients with chronic kidney disease. High phosphate can induce endothelial cell apoptosis, but the exact mechanism is not clear. This study fills this knowledge gap.
  
  
  METHODS
  Microarray analysis was used to identify differentially expressed gene profiles in human umbilical vein endothelial cells (HUVECs) in high phosphate (3.0mM) and normal phosphate (1.0mM) medium. Microarray informatics analysis was used to explore key pathways and genes. High phosphate-induced apoptosis is marked by annexin V-FITC/PI staining and cleavage of caspase-3. Immunoblotting and quantitative real-time PCR were performed to identify the microarray analysis.
  
  
  RESULTS
  Our microarray informatics analysis reveals that the mitogen-activated protein kinase (MAPK) plays a key role. As suggested by gene coexpression network analysis, bone morphogenetic protein 4 (BMP4) gene is a potential key regulatory gene in high phosphate environment. Both the expressions of BMP4 protein and mRNA are decreased. Extracellular regulated protein kinases (ERKs) are activated, while the inhibition of ERK by U0126 increases the expression of BMP4. Both recombinant BMP4 protein pretreatment and U0126 pretreatment reduce the apoptosis of endothelial cells in simulated hyperphosphatemia. However, BMP4 protein pretreatment had no effect on the activation of ERK MAPK pathway.
  
  
  CONCLUSIONS
  Our results indicate that the inhibition of ERK MAPK pathway protects endothelial cells from apoptosis by upregulating bone morphogenetic protein 4 in endothelial cells exposed to hyperphosphatemia. Our study provides potential molecular targets for developing new strategies to reduce the endothelial cell apoptosis induced by high phosphate.
authors.affiliation: Department of Nephrology & Rheumatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Qin
authors.affiliation: Department of Nephrology & Rheumatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Tang
authors.affiliation: Department of Nephrology & Rheumatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China.
authors.forename: Bingqing
authors.initials: B
authors.lastname: Deng
authors.affiliation: Department of Biomedical Engineering, University of Houston, 3605 Cullen Blvd, Room 2018, Houston, TX 77204, USA.
authors.forename: Chandra
authors.initials: C
authors.lastname: Mohan
authors.affiliation: Department of Biomedical Engineering, University of Houston, 3605 Cullen Blvd, Room 2018, Houston, TX 77204, USA.
authors.forename: Tianfu
authors.initials: T
authors.lastname: Wu
authors.affiliation: Department of Nephrology & Rheumatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China. Electronic address: pengai@tongji.edu.cn.
authors.forename: Ai
authors.initials: A
authors.lastname: Peng
mesh_terms: D017209:Apoptosis / Q000502:physiology; D055415:Bone Morphogenetic Protein 4 / Q000235:genetics / Q000378:metabolism*; D002070:Butadienes / Q000494:pharmacology; D053148:Caspase 3 / Q000378:metabolism; D061307:Human Umbilical Vein Endothelial Cells / Q000378:metabolism*; D006801:Humans; D054559:Hyperphosphatemia / Q000503:physiopathology*; D020935:MAP Kinase Signaling System / Q000502:physiology; D046228:Microarray Analysis; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D010710:Phosphates / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D015854:Up-Regulation
chemical_list: D055415:Bone Morphogenetic Protein 4; D002070:Butadienes; D009570:Nitriles; D010710:Phosphates; C113580:U 0126; D020928:Mitogen-Activated Protein Kinases; D053148:Caspase 3
keywords: Apoptosis; Bone morphogenetic protein 4; Endothelial cells; Extracellular regulated protein kinases; Hyperphosphatemia