title: VEGF-A inhibition ameliorates podocyte apoptosis via repression of activating protein 1 in diabetes.
abstract: OBJECTIVE
  Vascular endothelial growth factor-A (VEGF-A) upregulation and podocyte apoptosis have been documented in diabetes. This study was designed to investigate whether inhibiting VEGF-A could ameliorate podocyte apoptosis in diabetes and the underlying mechanisms.
  
  
  METHODS
  In vitro, small interfering RNAs (siRNAs) of VEGF-A and activator protein 1 (AP-1, c-fos and c-jun), bevacizumab (VEGF-A inhibitor) and SP600125 (AP-1 inhibitor) were added to high glucose (30 mM) induced podocytes. Luciferase reporter assay was used to investigate whether AP-1 was a direct target of VEGF-A. In vivo, bevacizumab and SP600125 were administered to 12-week-old streptozotocin-induced male Sprague Dawley rats. The level of VEGF-A, c-fos, c-jun and bcl-2 were examined using immunostaining and Western blot analysis. Podocyte apoptosis was detected using the terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end labeling (TUNEL) assay, electron microscopy and flow cytometry.
  
  
  RESULTS
  Silencing VEGF-A or AP-1 upregulated bcl-2 and ameliorated podocyte apoptosis. Silencing VEGF-A decreased the level of c-fos and c-jun and bevacizumab and SP600125 treatment attenuated podocyte apoptosis. Luciferase reporter activity of VEGF-A-3'-UTR constructs was significantly provoked when stimulated with TGF-β1. In diabetic rat kidneys, VEGF-A co-localized with bcl-2 in podocytes. With bevacizumab and SP600125 treatment, the level of VEGF-A and AP-1 decreased while bcl-2 increased. Podocyte apoptotic rate was reduced with condensed podocyte nuclei less frequently observed. The urine albumin excretion rate (UAER) and albumin/creatinine were improved.
  
  
  CONCLUSIONS
  This study demonstrates VEGF-A inhibition ameliorates podocyte apoptosis by regulating AP-1 and bcl-2 signaling. AP-1 is a direct target of VEGF-A and a novel player in podocyte apoptosis.
authors.affiliation: Division of Nephrology, Nanfang Hospital, Southern Medical University, National Clinical Medical Research Center for Kidney Disease, National Key Lab for Organ Failure Research, Guangdong Provincial Institute of Nephrology, Guangzhou, Guangdong, PR China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Bai
authors.forename: Jian
authors.initials: J
authors.lastname: Geng
authors.forename: Xiao
authors.initials: X
authors.lastname: Li
authors.forename: Fang
authors.initials: F
authors.lastname: Yang
authors.forename: Jianwei
authors.initials: J
authors.lastname: Tian
mesh_terms: D000419:Albuminuria / Q000652:urine; D020533:Angiogenesis Inhibitors / Q000494:pharmacology; D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D061067:Antibodies, Monoclonal, Humanized / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D000068258:Bevacizumab; D001786:Blood Glucose / Q000187:drug effects; D003404:Creatinine / Q000652:urine; D003921:Diabetes Mellitus, Experimental / Q000139:chemically induced / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D050199:Podocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering; D017207:Rats, Sprague-Dawley; D013311:Streptozocin; D018808:Transcription Factor AP-1 / Q000235:genetics; D014162:Transfection; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism
chemical_list: D020533:Angiogenesis Inhibitors; D000873:Anthracenes; D061067:Antibodies, Monoclonal, Humanized; D001786:Blood Glucose; D019253:Proto-Oncogene Proteins c-bcl-2; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D034741:RNA, Small Interfering; D018808:Transcription Factor AP-1; D042461:Vascular Endothelial Growth Factor A; C432165:pyrazolanthrone; D000068258:Bevacizumab; D013311:Streptozocin; D003404:Creatinine