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Yuri Seo, Yong Woo Ji, Hyemi Noh, Areum Yeo, Eung Kweon Kim, Hyung Keun Lee; Observation of ER stress induction in dry eye induced mouse lacrimal galnds acinar cells.. Invest. Ophthalmol. Vis. Sci. 2014;55(13):59. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Most of dry eye studies using murine models are mainly focused on the ocular surface , the key area of patient complaints. However, fundamentally, the pathophysiology of Dry eye (DE) lies on the change of tear flow. So, we hereby observed the morphologic and functional changes of tear production organ, lacrimal glands(LG) with several imaging techniques. The purpose of our study is to investigate the microscopic morphologic changes of LG through DE induced mice using light microscopy and electron microscopy for investigating LG dysfunction.
Six to 8-weeks-old(C57BL/6) mice(Charles River Laboratory, Wilmington MA) were placed in a low humidity controlled environment chamber(<20% of humidity) and supplemented with subcutaneous injections of 0.1mL of scopolamine hydrobromide, 5mg/mL(Sigma-Adlrich Chemical Co., St. Louis, MO), 3 times a day for the duration of the experiment. After 2 DE induction, mice were sacrificed and their lids, eyeballs, and LGs were collected. Each tissue was halved. One half was fixed by 3.7% paraformaldehyde and was immunostained. The other half was stored at -70°C for qRT-PCR. Sizes of lacrimal glands were measured grossly. Apoptosis of lacrimal gland acinar cell was evaluated by TUNEL staining. Lacrimal gland acinar cell organelle structures were observed with TEM(transmission electron microscope). ER(Endoplasmic Reticulum) stress and autophagy level in mice lacrimal gland were quantified using immunoblot and qRT-PCR.
Under the TEM(transmission electron microscope), increased density and dilation of ER lumen were observed. Also, mitochondrial swelling and destruction of cristae structure were observed. Additionally, increased number of vacuoles and elongation of ER surrounding cell organelle were detected. The marker of ER stress and the UPR(Unfolded Protein Response) pathways, PERK was significantly activated and eIF2α was significantly inactivated in lacrimal glands of DE induced mice. In addition, an autophagy marker, LC3 was activated in DE induced LG.
Activation of ER stress pathway and autophagy were confirmed by electron microscopic analysis as well as molecular biologic works. These changes occur from the early period of DE induction. The detailed mechanisms for activation of ER stress, functional role of these changes in DE induced murine model, and the consequential changes of ocular surface should be studied in the future.
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