SLC4A11 depletion impairs NRF2 mediated antioxidant signaling and increases reactive oxygen species in human corneal endothelial cells during oxidative stress

Sanjukta Guha,Sanhita Roy,Charanya Ramachandran,Sunita Chaurasia

doi:10.1038/s41598-017-03654-4

Sanjukta Guha, Sanhita Roy + Show 2 more

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https://doi.org/10.1038/s41598-017-03654-4

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Abstract

Corneal endothelial dystrophy is a progressive disease with gradual loss of vision and characterized by degeneration and dysfunction of corneal endothelial cells. Mutations in SLC4A11, a Na+ dependent OH− transporter, cause congenital hereditary endothelial dystrophy (CHED) and Fuchs’ endothelial corneal dystrophy (FECD), the two most common forms of endothelial degeneration. Along with genetic factors, oxidative stress plays a role in pathogenesis of several corneal diseases. In this study we looked into the role of SLC4A11 in antioxidant stress response in human corneal endothelial cells (HCEnC). We found increased expression of SLC4A11 in presence of oxidative stress. Depletion of SLC4A11 using targeted siRNA, caused an increase in reactive oxygen species, cytochrome c, lowered mitochondrial membrane potential, and reduced cell viability during oxidative stress. Moreover, SLC4A11 was found to be necessary for NRF2 mediated antioxidant gene expression in HCEnC. On the other hand, over expression of SLC4A11 reduces reactive oxygen species levels and increases cell viability. Lastly, CHED tissue specimens show evidence of oxidative stress and reduced expression of NRF2. In conclusion, our data suggests a possible role of SLC4A11 in regulating oxidative stress, and might be responsible for both the etiology and treatment of corneal endothelial dystrophy.

Highlights

Corneal endothelial dystrophy results in degeneration and dysfunction of endothelial cells of the cornea, thickening of the Descemet’s membrane (DM) and is characterized by loss in endothelial cell density[1]
Oxidative stress has been associated with pathogenesis of corneal endothelial dystrophy[28] and other corneal diseases[29]
Oxidative stress induced expression of heme oxygenase 1 (HO-1), an antioxidant gene regulated by Nuclear factor erythroid 2-related factor 2 (NRF2), by nearly 4 folds in primary cells (Fig. 1a) and about 40 folds in the immortalized cells (Fig. 1b)

Summary

Introduction

Corneal endothelial dystrophy results in degeneration and dysfunction of endothelial cells of the cornea, thickening of the Descemet’s membrane (DM) and is characterized by loss in endothelial cell density[1]. CHED and FECD are two major forms of corneal endothelial dystrophies that lead to progressive opacity of the cornea and gradual vision loss and are associated with mutations in SLC4A11 gene[2,3,4]. While mutations and loss of functional SLC4A11 are reported to be associated with degeneration and death of endothelial cells, the detailed physiological roles of SLC4A11 still remain unknown. Our studies show that depletion of SLC4A11 in corneal endothelial cells generates increased ROS, alters mitochondrial membrane potential and results in impaired NRF2 driven antioxidant signaling. This study sheds light on physiological function of SLC4A11 during oxidative stress that can lead to the development of important noninvasive therapeutic interventions to prevent corneal endothelial degeneration

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