Role of metallothioneins 1 and 2 in ocular neovascularization.

Abstract

PURPOSE:

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: Shinsuke Nakamura, Masamitsu Shimazawa, Yuki Inoue, Shinsuke Takata, Yasushi Ito, Kazuhiro Tsuruma, Tsunehiko Ikeda, Akiko Honda, Masahiko Satoh, Hideaki Hara
• Journal: Investigative ophthalmology & visual science (Invest Ophthalmol Vis Sci) Vol. 55 Issue 10 Pg. 6851-6860 (Sep 23 2014) ISSN: 1552-5783 [Electronic] United States
• PMID: 25249600 (Publication Type: Journal Article)
• Copyright: Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Chemical References

• Matrix Metalloproteinase 2
• Matrix Metalloproteinase 1

Topics

• Aged
• Animals
• Blotting, Western
• Disease Models, Animal
• Enzyme-Linked Immunosorbent Assay
• Eye Diseases (enzymology, pathology)
• Female
• Fluorescein Angiography
• Fundus Oculi
• Humans
• Immunoblotting
• Immunohistochemistry
• Male
• Matrix Metalloproteinase 1 (metabolism)
• Matrix Metalloproteinase 2 (metabolism)
• Mice
• Mice, Inbred C57BL
• Mice, Knockout
• Middle Aged
• Neovascularization, Pathologic (enzymology, pathology)
• Vitreous Body (enzymology)