September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Unfolded protein accumulation induced endoplasmic reticulum stress of corneal endothelial cells in Fuchs endothelial corneal dystrophy
Author Affiliations & Notes
  • Naoki Okumura
    Doshisha University, Kyotanabe, Japan
  • Keisuke Hashimoto
    Doshisha University, Kyotanabe, Japan
  • Miu Kitahara
    Doshisha University, Kyotanabe, Japan
  • Makiko Nakahara
    Doshisha University, Kyotanabe, Japan
  • Shigeru Kinoshita
    Kyoto Prefectural University of Medicine, Kyoto, Japan
  • Theofilos Tourtas
    University of Erlangen-Nürnberg, Erlangen, Germany
  • Ursula Schlötzer-Schrehardt
    University of Erlangen-Nürnberg, Erlangen, Germany
  • Friedrich E Kruse
    University of Erlangen-Nürnberg, Erlangen, Germany
  • Noriko Koizumi
    Doshisha University, Kyotanabe, Japan
  • Footnotes
    Commercial Relationships   Naoki Okumura, Doshisha university (P), Senju Pharmaceutical Co. (P); Keisuke Hashimoto, None; Miu Kitahara, None; Makiko Nakahara, None; Shigeru Kinoshita, Senju Pharmaceutical Co. (P) (P); Theofilos Tourtas, None; Ursula Schlötzer-Schrehardt, None; Friedrich Kruse, None; Noriko Koizumi, Doshisha university (P), Senju Pharmaceutical Co. (P)
  • Footnotes
    Support  Program for the Strategic Research Foundation at Private Universities from MEXT (Koizumi N and Okumura N).
Investigative Ophthalmology & Visual Science September 2016, Vol.57, No Pagination Specified. doi:
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      Naoki Okumura, Keisuke Hashimoto, Miu Kitahara, Makiko Nakahara, Shigeru Kinoshita, Theofilos Tourtas, Ursula Schlötzer-Schrehardt, Friedrich E Kruse, Noriko Koizumi; Unfolded protein accumulation induced endoplasmic reticulum stress of corneal endothelial cells in Fuchs endothelial corneal dystrophy. Invest. Ophthalmol. Vis. Sci. 201657(12):.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : The unfolded protein response (UPR) is activated by a response to endoplasmic reticulum (ER) stress and is thought to be involved in Fuchs endothelial corneal dystrophy (FECD). We reported that transforming growth factor beta (TGF-β) signaling is involved in the pathogenesis of FECD (Okumura N, et al. Lab Invest. 2015). This study investigated how ER stress is induced in FECD and the feasibility of TGF-β signaling inhibition as a potent therapeutic target.

Methods : Human corneal endothelial specimens from 22 FECD patients and 19 healthy donor corneas were examined by staining of unfolded protein, type-I collagen, fibronectin, and molecular chaperone (GRP78). Immortalized human corneal endothelial cells (CECs) derived from normal donor corneas (iHCEC) and FECD patient corneas (iFECD) were also stained. ER stress sensors (IRE1, PERK, and ATF6) caspase 9 and 3 were analyzed by western blotting, and mitochondrial membrane potential (MMP) was analyzed by flow cytometry in the iFECD and iHCEC. To evaluate the relation between unfolded protein and cell damage, iHCEC was stimulated with MG132. Unfolded protein was then stained and ER stress sensors caspase 9 and 3 were examined by western blotting. To evaluate the feasibility of TGF-β signaling pathway inhibition, iFECD was treated with TGF-β receptor inhibitor SB431542, and unfolded protein accumulation and MMP were examined.

Results : A higher amount of unfolded protein and GRP78 was expressed in the FECD corneal endothelium than in the control. Immunocytochemistry showed that type-I collagen and fibronectin were colocalized to unfolded protein. Similarly, expression of unfolded protein was higher in iFECD associated with ER stress sensor activation than in iHCEC. MMP was decreased in iFECD compared with iHCEC (41.7±10.2% and 15.5±1.7%, respectively)(p<0.01). MG132 induced unfolded protein accumulation and activated ER stress sensors. Subsequently, MMP was decreased and caspase 9 and 3 was activated. SB431542 reduced unfolded protein accumulation and recovered the MMP drop in iFECD.

Conclusions : Our findings show that ER stress activated by unfolded protein accumulation induces CEC damage, at least partially, via mitochondria-dependent apoptosis. TGF-β signaling pathway inhibition may be a potent FECD therapy by suppressing UPR via reducing unfolded protein accumulation.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

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