ABSTRACT
PURPOSE: The objective of this study was to investigate the senescent phenotypes of human corneal endothelial cells (hCEnCs) upon treatment with ultraviolet (UV)-A. METHODS: We assessed cell morphology, senescence-associated ß-galactosidase (SA-ß-gal) activity, cell proliferation and expression of senescence markers (p16 and p21) in hCEnCs exposed to UV-A radiation, and senescent hCEnCs induced by ionizing radiation (IR) were used as positive controls. We performed RNA sequencing and proteomics analyses to compare gene and protein expression profiles between UV-A- and IR-induced senescent hCEnCs, and we also compared the results to non-senescent hCEnCs. RESULTS: Cells exposed to 5 J/cm2 of UV-A or to IR exhibited typical senescent phenotypes, including enlargement, increased SA-ß-gal activity, decreased cell proliferation and elevated expression of p16 and p21. RNA-Seq analysis revealed that 83.9% of the genes significantly upregulated and 82.6% of the genes significantly downregulated in UV-A-induced senescent hCEnCs overlapped with the genes regulated in IR-induced senescent hCEnCs. Proteomics also revealed that 93.8% of the proteins significantly upregulated in UV-A-induced senescent hCEnCs overlapped with those induced by IR. In proteomics analyses, senescent hCEnCs induced by UV-A exhibited elevated expression levels of several factors part of the senescence-associated secretory phenotype. CONCLUSIONS: In this study, where senescence was induced by UV-A, a more physiological stress for hCEnCs compared to IR, we determined that UV-A modulated the expression of many genes and proteins typically altered upon IR treatment, a more conventional method of senescence induction, even though UV-A also modulated specific pathways unrelated to IR.
Subject(s)
Cell Proliferation , Cellular Senescence , Endothelial Cells , Ultraviolet Rays , Humans , Cellular Senescence/radiation effects , Ultraviolet Rays/adverse effects , Cell Proliferation/radiation effects , Endothelial Cells/radiation effects , Endothelial Cells/metabolism , Endothelium, Corneal/radiation effects , Endothelium, Corneal/metabolism , Cells, Cultured , Proteomics , Cyclin-Dependent Kinase Inhibitor p21/metabolism , Cyclin-Dependent Kinase Inhibitor p21/genetics , beta-Galactosidase/metabolism , beta-Galactosidase/genetics , Cyclin-Dependent Kinase Inhibitor p16/metabolism , Cyclin-Dependent Kinase Inhibitor p16/geneticsABSTRACT
PURPOSE: This study aimed to investigate the senescent phenotypes of human corneal and conjunctival epithelial cells. METHODS: We examined cell morphology, senescence-associated ß-galactosidase (SA-ß-gal) activity, cell proliferation, and expression of senescence markers (p16 and p21). RNA sequencing analysis was conducted to compare gene expression profiles between senescent and non-senescent cells. Finally, the potential involvement of senescent cells in the pathogenesis of ocular surface diseases was investigated. RESULTS: X-irradiated corneal and conjunctival epithelial cells exhibited typical senescence phenotypes, i.e., flattened morphologies, increased SA-ß-gal activity, decreased cell proliferation, and increased expression of senescence markers, p16 and p21. RNA-seq analysis revealed substantial differences in gene expression profiles between senescent corneal (SCo) and conjunctival epithelial cells (SCj). Moreover, SCj were detected in pathological conjunctival tissues associated with limbal stem cell deficiency (LSCD) due to Stevens-Johnson syndrome or chemical burns, potentially being involved in abnormal differentiation. CONCLUSION: This study highlights the cellular and molecular characteristics of senescent ocular surface cells, particularly in SCj that show abnormal keratin expression, and their potential roles in severe ocular surface diseases and pathology.
