Comprehensive Analysis Identified the Circadian Clock and Global Circadian Gene Expression in Human Corneal Endothelial Cells

Abstract

Purpose To investigate circadian clock oscillation and circadian global gene expression in cultured human corneal endothelial cells (cHCECs) to elucidate and assess the potential function of circadian regulation in HCECs. Methods In this study, we introduced a circadian bioluminescence reporter, Bmal1:luciferase ( Bmal1:luc ), into cHCECs and subsequently monitored real-time bioluminescence rhythms. RNA-sequencing data analysis was then performed using sequential time-course samples of the cHCECs to obtain a comprehensive understanding of the circadian gene expression rhythms. The potential relevance of rhythmically expressed genes was then assessed by systematic approaches using functional clustering and individual gene annotations. Results Bmal1:luc bioluminescence exhibited clear circadian oscillation in the cHCECs. The core clock genes and clock-related genes showed high-amplitude robust circadian messenger RNA (mRNA) expression rhythms in cHCECs after treatment with dexamethasone, and 329 genes that exhibited circadian mRNA expression rhythms were identified (i.e., genes involved in various physiological processes including glycolysis, mitochondrial function, antioxidative systems, hypoxic responses, apoptosis, and extracellular matrix regulation, which represent the physiological functions of HCECs). Conclusions Our findings revealed that cHCECs have a robust and functional circadian clock, and our discovery that a large number of genes exhibit circadian mRNA expression rhythms in cHCECs suggests a potential contribution of circadian regulation to fine-tune HCEC functions for daily changes in the environment.

A multi-ancestry GWAS of Fuchs corneal dystrophy highlights the contributions of laminins, collagen, and endothelial cell regulation

“…Although RORA shares structural features with retinoic acid receptors (RARs), it does not have known ligand-binding properties with retinol. RORA is commonly associated with regulation of BMAL1 and circadian rhythm; CECs have a highly robust circadian clock, and FECD and other corneal maladies are known to exhibit diurnal variation 40 . RORA is induced by oxidative stress; reduction of NFE2L2 nuclear factor translocation, which leads to downregulation of antioxidant expression, has previously been observed in FECD cases 41 .…”

Multi-ancestry GWAS of Fuchs corneal dystrophy highlights roles of laminins, collagen, and endothelial cell regulation

“…Although it shares structural features with retinoic acid receptors (RARs), RORA does not have known ligand-binding properties with retinol. RORA is most commonly associated with regulation of BMAL1 and circadian rhythm; CECs have a highly robust circadian clock, and FECD and other corneal maladies are known to exhibit diurnal variation 57 . RORA is induced by oxidative stress; reduction of NFE2L2 nuclear factor translocation, which leads to downregulation of antioxidant expression, has previously been observed in FECD cases 58 .…”

LimoRhyde2: genomic analysis of biological rhythms based on effect sizes

“…Among genes ranked highly by LimoRhyde2 in the lung were Fkbp5 and Adamts4. The former encodes a negative-feedback regulator of glucocorticoid signaling [57], which plays an important role in synchronizing daily rhythms across tissues [58], while the latter is a clock-controlled gene in mouse cartilage [59] and human corneal endothelial cells [60]. Among genes ranked highly in the SCN were Nfkbib, which encodes an inhibitor of NF-κB signaling and whose expression is regulated in microglia by the clock gene Nr1d1 [61], and Id1, which may play a role in photic entrainment of the circadian system [62].…”