title: The mechanism of CCN1-enhanced retinal neovascularization in oxygen-induced retinopathy through PI3K/Akt-VEGF signaling pathway.
abstract: BACKGROUND
  CCN1 (also called Cyr 61) is an extracellular matrix signaling molecule that has been implicated in neovascularization through its interactions with several endothelial integrin receptors. The roles of vascular endothelial growth factor (VEGF) in angiogenesis are well described. The aim of this study was to investigate the signal transduction mechanism of CCN1-PI3K/Akt-VEGF in retinopathy of prematurity (ROP), and the effects of CCN1 knockdown on ROP.
  
  
  METHODS
  The oxygen-induced retinopathy (OIR) model was established in C57BL/6J mice exposed to a high concentration of oxygen. Retinas were obtained from the normoxia, OIR, OIR control (treated with scramble siRNA) and OIR treated (with CCN1 siRNA) groups. Retinal neovascularization (RNV) was qualitatively analyzed with ADPase staining and quantitatively analyzed by counting neovascular endothelial cell nuclei at postnatal day 17 when RNV reached a peak. mRNA level and protein expression of CCN1, p-Akt, and VEGF were measured by real-time PCR and Western blotting, and located with immunohistochemistry.
  
  
  RESULTS
  CCN1 depletion resulted in less neovascularization clock hour scores in the number of preretinal neovascular cells compared with the OIR treated group (1.28±0.83 versus 4.80±0.82; and 7.12±2.50 versus 23.25±2.35, respectively, both P<0.05). Furthermore, CCN1, p-Akt and VEGF mRNA, and protein were significantly expressed in the retina of the OIR and OIR control groups. Intravitreal injection of CCN1 siRNA significantly reduced PI3K/Akt-VEGF pathway expression of the OIR mouse model (all P<0.05). CCN1 siRNA significantly enhanced the avascular area and avascular diameter of OIR model (P<0.05). CCN1 siRNA decreased the levels of IL-1β, IL-6, and TNF-α significantly compared to the OIR group (P<0.05).
  
  
  CONCLUSIONS
  These results suggest that CCN1 plays an important role in RNV via the PI3K/Akt-VEGF signaling pathway. CCN1 may be a potential target for the prevention and treatment of ROP.
authors.affiliation: Department of Ophthalmology, Shengjing Affiliated Hospital of China Medical University, Shenyang, People's Republic of China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Di
authors.affiliation: Graduate School, China Medical University, Shenyang, People's Republic of China.
authors.forename: Yiou
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Ophthalmology, Shengjing Affiliated Hospital of China Medical University, Shenyang, People's Republic of China.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Yang
authors.affiliation: Department of Ophthalmology, Shengjing Affiliated Hospital of China Medical University, Shenyang, People's Republic of China.
authors.forename: Aiyuan
authors.initials: A
authors.lastname: Wang
authors.affiliation: Department of Ophthalmology, Shengjing Affiliated Hospital of China Medical University, Shenyang, People's Republic of China.
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Chen
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001081:Apyrase / Q000378:metabolism; D055515:Cysteine-Rich Protein 61 / Q000187:drug effects / Q000235:genetics*; D016207:Cytokines / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects; D005260:Female; D055785:Gene Knockdown Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D051058:Oncogene Protein v-akt / Q000502:physiology; D010100:Oxygen / Q000633:toxicity; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D034741:RNA, Small Interfering / Q000494:pharmacology; D015861:Retinal Neovascularization / Q000188:drug therapy*; D012178:Retinopathy of Prematurity / Q000139:chemically induced / Q000188:drug therapy*; D015398:Signal Transduction / Q000187:drug effects*; D042461:Vascular Endothelial Growth Factor A / Q000502:physiology
chemical_list: D001081:Apyrase; D055515:Cysteine-Rich Protein 61; D016207:Cytokines; D051058:Oncogene Protein v-akt; D010100:Oxygen; D019869:Phosphatidylinositol 3-Kinases; D034741:RNA, Small Interfering; D042461:Vascular Endothelial Growth Factor A; C491850:CCN1 protein, mouse
keywords: cysteine-rich 61; retinal neovascularization; retinopathy of prematurity; vascular endothelial growth factor