Inhibition of JAK2/STAT3-mediated VEGF upregulation under high glucose conditions by PEDF through a mitochondrial ROS pathway in vitro.
OBJECTIVE
Hyperglycemia-induced mitochondrial reactive oxygen species (ROS) production plays an important role in the development of complications of diabetes such as retinopathy. However, whether pigment epithelium-derived factor (PEDF) can decrease ROS production remains uncertain. The aim of this study was to clarify whether PEDF can decrease mitochondria-derived ROS generation and subsequently downregulate vascular endothelial growth factor (VEGF) expression; the authors also investigated the involvement of Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) in the process.


METHODS
Bovine retinal capillary endothelial cells (BRECs) were exposed to normal glucose (NG), H(2)O(2), or high glucose (HG) in the presence or absence of PEDF. Expression of JAK2/STAT3, VEGF, uncoupling protein (UCP)-2, and proliferator-activated receptor gamma (PPARgamma) in the BRECs was examined by Western blot analysis assay; VEGF and UCP-2 mRNA were determined by real-time RT-PCR. Mitochondrial membrane potential (Deltapsim) and ROS production were assayed using JC-1 and CM-H2DCFDA, respectively.


RESULTS
HG exposure caused hyperpolarization of Deltapsim and increased ROS generation in BRECs; meanwhile, like H(2)O(2), it also induced the phosphorylation of JAK2/STAT3 and increased VEGF expression; these changes were inhibited by PEDF. The authors also found that PEDF-induced ROS inhibition was a result of decreased Deltapsim, which was caused by the upregulation of PPARgamma and UCP-2 expression.


CONCLUSIONS
For the first time it has been demonstrated that PEDF can decrease mitochondria-derived ROS generation and subsequently downregulate VEGF expression, possibly through inhibiting HG-induced JAK2/STAT3 activation, which may offer a promising strategy for halting the development of complications of diabetes.
Zheng
Zhi
Z
Department of Ophthalmology, Shanghai First People's Hospital Affiliated Shanghai Jiao Tong University, Shanghai, China.
Chen
Haibing
H
Zhao
Hui
H
Liu
Kun
K
Luo
Dawei
D
Chen
Yongdong
Y
Chen
Yihui
Y
Yang
Xiaolu
X
Gu
Qing
Q
Xu
Xun
X
D000818:Animals; D015153:Blotting, Western; D002417:Cattle; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005136:Eye Proteins / Q000494:pharmacology*; D005947:Glucose / Q000494:pharmacology*; D006861:Hydrogen Peroxide / Q000633:toxicity; D006943:Hyperglycemia / Q000378:metabolism; D007473:Ion Channels / Q000235:genetics / Q000378:metabolism; D053614:Janus Kinase 2 / Q000378:metabolism*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D019255:NADPH Oxidases / Q000378:metabolism; D009414:Nerve Growth Factors / Q000494:pharmacology*; D047495:PPAR gamma / Q000378:metabolism; D010766:Phosphorylation; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012171:Retinal Vessels / Q000166:cytology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D015843:Serpins / Q000494:pharmacology*; D000071246:Uncoupling Protein 2; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*; D000099174:Pigment Epithelium-Derived Factor
D005136:Eye Proteins; D005947:Glucose; D006861:Hydrogen Peroxide; D007473:Ion Channels; D053614:Janus Kinase 2; D024101:Mitochondrial Proteins; D019255:NADPH Oxidases; D009414:Nerve Growth Factors; D047495:PPAR gamma; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D050796:STAT3 Transcription Factor; D015843:Serpins; D000071246:Uncoupling Protein 2; D042461:Vascular Endothelial Growth Factor A; D000099174:Pigment Epithelium-Derived Factor