Localization of the ultraviolet-sensor Opn5m and its effect on myopia-related gene expression in the late-embryonic chick eye

Mutsuko Kato; Keita Sato; Munenori Habuta; Hirofumi Fujita; Tetsuya Bando; Yuki Morizane; Fumio Shiraga; Satoru Miyaishi; Hideyo Ohuchi

doi:10.1016/j.bbrep.2019.100665

Localization of the ultraviolet-sensor Opn5m and its effect on myopia-related gene expression in the late-embryonic chick eye

Biochem Biophys Rep. 2019 Jul 19:19:100665. doi: 10.1016/j.bbrep.2019.100665. eCollection 2019 Sep.

Authors

Mutsuko Kato¹, Keita Sato¹, Munenori Habuta¹, Hirofumi Fujita¹, Tetsuya Bando¹, Yuki Morizane², Fumio Shiraga², Satoru Miyaishi³, Hideyo Ohuchi¹

Affiliations

¹ Department of Cytology and Histology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Japan, 2-5-1 Shikata-cho, Kita-ku, Okayama, 700-8558, Japan.
² Department of Ophthalmology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Japan, 2-5-1 Shikata-cho, Kita-ku, Okayama, 700-8558, Japan.
³ Department of Legal Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Japan, 2-5-1 Shikata-cho, Kita-ku, Okayama, 700-8558, Japan.

Abstract

Recent studies show that exposure to ultraviolet (UV) light suppresses ocular elongation, which causes myopia development. However, the specific mechanisms of this process have not been elucidated. A UV-sensor, Opsin 5 (Opn5) mRNA was shown to be present in extraretinal tissues. To test the possibility that UV-signals mediated by Opn5 would have a direct effect on the outer connective tissues of the eye, we first examined the expression patterns of a mammalian type Opn5 (Opn5m) in the late-embryonic chicken eye. Quantitative PCR showed Opn5m mRNA expression in the cornea and sclera. The anti-Opn5m antibody stained a small subset of cells in the corneal stroma and fibrous sclera. We next assessed the effect of UV-A (375 nm) irradiation on the chicken fibroblast cell line DF-1 overexpressing chicken Opn5m. UV-A irradiation for 30 min significantly increased the expression of Early growth response 1 (Egr1), known as an immediate early responsive gene, and of Matrix metalloproteinase 2 (Mmp2) in the presence of retinal chromophore 11-cis-retinal. In contrast, expression of Transforming growth factor beta 2 and Tissue inhibitor of metalloproteinase 2 was not significantly altered. These results indicate that UV-A absorption by Opn5m can upregulate the expression levels of Egr1 and Mmp2 in non-neuronal, fibroblasts. Taken together with the presence of Opn5m in the cornea and sclera, it is suggested that UV-A signaling mediated by Opn5 in the extraretinal ocular tissues could influence directly the outer connective tissues of the chicken late-embryonic eye.

Keywords: Chicken; Egr1; Egr1, Early growth response 1; Fibroblasts; Gapdh, Glyceraldehyde-3-phosphate dehydrogenase; MAP kinase, mitogen-activated protein kinase; Mmp2; Mmp2, Matrix metalloproteinase 2; Opn5, Opsin 5; Opn5m, mammalian type Opn5; Opsin 5; Tgfb2, Transforming growth factor beta 2; Timp2, Tissue inhibitor of metalloproteinase 2; UV, ultraviolet; UV-A, ultraviolet-A; UV-Absorbing pigment; cAMP, cyclic adenosine monophosphate; qPCR, quantitative polymerase chain reaction.