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Nobuyuki EBIHARA3), Akira MURAKAMI2), Takeshi IWATA1)Zai-Long CHI1), Masakazu AKAHORI1), Nobuhiro SHIMOZAWA4), 3)Department of Ophthalmology, Juntendo University Urayasu Hospital, Chiba, Japan2)Department of Ophthalmology, Graduate School of Medicine, Juntendo University, Tokyo, Japan4)Tsukuba Primate Research Center, National Institute of Biomedical Innovation, Ibaraki, Japan1)National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, JapanKazuhiko TANABE1, 2, 3), Itaru KIMURA1), Haru OKAMOTO1), Corresponding author: Itaru KimuraDivision on Molecular & Cellular Biology, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center2-5-1 Higashigaoka, Meguro-ku, Tokyo 152-8902 JapanTEL/FAX: +81-3-3411-1026　E-mail: kimuraitaru@gmail.com〔Received　Nov. 29, 2021〕〔Accepted　Mar. 14, 2022〕J-STAGE Advance published date: Jul. 14, 2022Copyright © 2022 The Juntendo Medical Society. This is an open access article distributed under the terms of Creative Commons Attribution License (CC BY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original source is properly credited. doi: 10.14789/jmj.JMJ21-0042-OAPurpose: The purpose of this study was to determine what proteins are present in the ciliary body (CB). To accomplish this, we conducted a proteomic analysis of the CB of cynomolgus monkeys. We also determined the location of the proteins in CB by immunohistology.Methods: The eyes of euthanized cynomolgus monkeys were enucleated, and the CB, were isolated from the eyes. Proteins were extracted from the CB and determined by liquid chromatography-mass spectrometry. Separated CB epithelial cells were cultured, and the proteins expressed in the CB were determined by Western blotting. The location of these proteins in the CB was determined by immunohistochemical staining. We also investigated whether adding dexamethasone to the culture medium changed protein expression by the epithelial cells.Results: Proteomic analysis of the CBs showed that 813 proteins were expressed in the epithelium and stroma. These proteins included the small guanosine triphosphate-binding protein Rab8 and the ezrin/radixin/moesin (ERM) family. Tissue and immunohistological staining confirmed the colocalization of these proteins in non-pigmented CB epithelium. Western blotting of cultured CB epithelial cell lysates showed a tendency that adding dexamethasone changed Rab8 protein expression levels.Conclusions: Proteomic analysis of CBs identified several proteins involved in the transport and secretion of proteins. These proteins may be involved in the production of aqueous humor and protein secretion by the CB.Key words: ciliary body, rab8, ezrin, radixin, moesinJuntendo Medical Journal2022. 68(4), 339-351Original ArticlesIntroductionGlaucoma is a major cause of blindness world-wide: Approximately 60 million people have glau-coma, and approximately 8 million of them are blind in both eyes1, 2). The disease is characterized by a progressive loss of retinal ganglion cells, resulting in constriction of the visual fields2, 3). Elevated intraocular pressure (IOP) enhances the progression of the disease processes, and a reduc-tion of IOP can slow or block the progression of glaucoma. The IOP can also affect aqueous humor dynamics4). Other components that influence IOP are the trabecular meshwork and Schlemm’s canal, which are involved in the outflow of aqueous humor, and the ciliary body (CB), which is involved 339The Expression of Rab8, Ezrin, Radixin and Moesin in the Ciliary Body of Cynomolgus Monkeys