title: Role of metallothioneins 1 and 2 in ocular neovascularization.
abstract: OBJECTIVE
  The incidence of blindness is increasing, in part, because of abnormal ocular neovascularization. Anti-VEGF therapies have yielded impressive results; however, they are not a cure for blindness. Recently, metallothioneins (MTs) 1 and 2 have been implicated in the process of angiogenesis. Therefore, we investigated whether MT-1 and MT-2 were also involved in ocular neovascularization.
  
  
  METHODS
  The concentrations of MT-1 and MT-2 (hereafter MT-1/2) were observed by ELISA. We examined the role of MT-1/2 in ocular neovascularization by using both an oxygen-induced retinopathy (OIR) model and a laser-induced choroidal neovascularization (CNV) model. We investigated the localization of MT-1/2 in retina. Furthermore, we investigated the expression of hypoxia-inducible factor (HIF)-1α and VEGF in OIR. In vitro, we investigated the degradation of HIF-1α.
  
  
  RESULTS
  The MT-1/2 were significantly elevated in proliferative diabetic retinopathy patients. Ocular neovascularization, which was induced in both the OIR model and the CNV model, was decreased in MT-1/2 knockout (KO) mice. We confirmed that although MT-1/2 was expressed throughout the murine retina, its expression levels were highest in the endothelial cells. Further, OIR enhanced MT-1/2 expression in the retina. Interestingly, in the OIR model, both HIF-1α and VEGF levels were significantly decreased in the retina of MT-1/2 KO mice. In addition, we found that knockdown of MT-1/2 accelerated ubiquitination of HIF-1α.
  
  
  CONCLUSIONS
  These results indicate that MT-1/2 are involved in retinal and choroidal neovascularization, and that MT-1/2 might be a new therapeutic target in diseases in which ocular angiogenesis is implicated.
authors.affiliation: Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Nakamura
authors.affiliation: Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan.
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Shimazawa
authors.affiliation: Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Inoue
authors.affiliation: Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Takata
authors.affiliation: Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Ito
authors.affiliation: Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Tsuruma
authors.affiliation: Department of Ophthalmology, Osaka Medical College, Osaka, Japan.
authors.forename: Tsunehiko
authors.initials: T
authors.lastname: Ikeda
authors.affiliation: Laboratory of Pharmaceutical Health Sciences, School of Pharmacy, Aichi Gakuin University, Nagoya, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Honda
authors.affiliation: Laboratory of Pharmaceutical Health Sciences, School of Pharmacy, Aichi Gakuin University, Nagoya, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Satoh
authors.affiliation: Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Hara
mesh_terms: D000368:Aged; D000818:Animals; D015153:Blotting, Western; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005128:Eye Diseases / Q000201:enzymology* / Q000473:pathology; D005260:Female; D005451:Fluorescein Angiography; D005654:Fundus Oculi; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D008297:Male; D020781:Matrix Metalloproteinase 1 / Q000378:metabolism*; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008875:Middle Aged; D009389:Neovascularization, Pathologic / Q000201:enzymology* / Q000473:pathology; D014822:Vitreous Body / Q000201:enzymology
chemical_list: D020778:Matrix Metalloproteinase 2; D020781:Matrix Metalloproteinase 1
keywords: HIF-1α; VEGF; metallothionein; neovascularization