The Role of Nuclear Factor of Activated T Cells 5 in Hyperosmotic Stress-Exposed Human Lens Epithelial Cells

Abstract

We investigated the role of nuclear factor of activated T cells 5 (NFAT5) under hyperosmotic conditions in human lens epithelial cells (HLECs). Hyperosmotic stress decreased the viability of human lens epithelial B-3 cells and significantly increased NFAT5 expression. Hyperosmotic stress-induced cell death occurred to a greater extent in NFAT5-knockout (KO) cells than in NFAT5 wild-type (NFAT5 WT) cells. Bcl-2 and Bcl-xl expression was down-regulated in NFAT5 WT cells and NFAT5 KO cells under hyperosmotic stress. Pre-treatment with a necroptosis inhibitor (necrostatin-1) significantly blocked hyperosmotic stress-induced death of NFAT5 KO cells, but not of NFAT5 WT cells. The phosphorylation levels of receptor-interacting protein kinase 1 (RIP1) and RIP3, which indicate the occurrence of necroptosis, were up-regulated in NFAT5 KO cells, suggesting that death of these cells is predominantly related to the necroptosis pathway. This finding is the first to report that necroptosis occurs when lens epithelial cells are exposed to hyperosmolar conditions, and that NFAT5 is involved in this process.

Changes in DNA methylation hallmark alterations in chromatin accessibility and gene expression for eye lens differentiation

“…7 B, Additional file 13 : Table S9B). Consistently, previous studies revealed a role for NFAT5 in the hyperosmotic stress response in human lens epithelial cells [ 85 ], SOX2 is a well-established transcription factor required for lens development [ 90 ], and the MAF family of transcription factors are known regulators of lens gene expression and lens development [ 76 , 77 , 79 – 81 ]. The data suggest that changes in DNA methylation within the identified regions regulate the ability of specific lens transcription factors to control gene expression changes during lens cell differentiation.…”

Overexpression of TRPV1 activates autophagy in human lens epithelial cells under hyperosmotic stress through Ca2+-dependent AMPK/mTOR pathway

“…We thus aimed to thoroughly investigate the mechanisms from an autophagy perspective, which is a direction relatively untouched given that previous studies mainly focused on the protein changes for this topic. We adopted a stricter standard of 600 mOsm for 6h, which studies have proven would lead to significant apoptosis of epithelial cells, leaving only a small number of functional cells [13][14] . This would minimize the chances of cells remaining viable by chance, helping us identify significant characteristics and mechanisms that would prevent apoptosis under an extreme hyperosmotic environment.…”