Egr1 Gene Expression as a Potential Biomarker for In Vitro Prediction of Ocular Toxicity

Abstract

Animal models are used for preclinical toxicity studies, and the need for in vitro alternative methods has been strongly raised. Our study aims to elucidate the potential mechanism of change in EGR1 expression under situations of toxic injury and to develop an Egr1 promoter–luciferase gene reporter assay for an in vitro alternative method for toxicity prediction in drug discovery. We first found an increase in early growth response-1 (EGR1) mRNA/protein expressions in the liver and kidney of cisplatin-treated injured rats. Additionally, the EGR1 protein level was also elevated under situations of ocular injury after sodium lauryl sulfate (SLS) eye drops. These in vivo observations on injury-related EGR1 induction were confirmed by in vitro studies, where human corneal epithelial cells were treated with representative irritants (SLS and benzalkonium chloride) and 17 chemicals having different UN GHS irritant categories. Additionally, our results suggest the involvement of ERK, JNK, p38 MAPK pathways in EGR1 elevation in response to gamma-butyrolactone-induced injury. As EGR1 is considered to be a pivotal factor in proliferation and regeneration, siRNA-mediated knockdown of Egr1 promoted cytotoxic potential through a delay of injury-related recovery. More importantly, the elevation of promoter activities was observed by various irritants in cells transfected with Egr1 promoter-reporter vector. In conclusion, Egr1 can be a potential biomarker in a promoter-reporter system to improve the accuracy of in vitro predictions for ocular irritation.

Leukemia inhibitory factor is a therapeutic target for renal interstitial fibrosis

“…Previous studies reported that EGR1 is the downstream target of LIF-STAT3 signaling and ERK signaling. 52 , 53 , 54 , 55 , 56 , 57 Accordingly, depletion of LIFR or EGR1 by siRNA diminished LIF-augmented SHH expression, indicating that SHH is a downstream target of LIF-LIFR-EGR1 axis in renal tubular cells ( Fig. 5 d–g).…”

“…Since EGR1 is the downstream target of ERK signaling and STAT3 signaling, 52 , 53 , 54 , 55 , 56 , 57 we sought LIF expression might be up-regulated by an autocrine pathway in fibroblasts. As expected, when NRK49F cells were incubated with indicated concentration of LIF for 24 h, both mRNA and protein level of LIF was increased in a dose-dependent manner ( Fig.…”

Inhibition of the MAPK/c-Jun-EGR1 Pathway Decreases Photoreceptor Cell Death in the rd1 Mouse Model for Inherited Retinal Degeneration

“…Since activation of the MAPK/c-Jun pathway can promote the expression of EGR1 [ 21 , 22 ], we examined EGR1 expression and photoreceptor death after administration of the JNK inhibitor tanzisertib and ERK inhibitor PD98059. Western blotting and the TUNEL assay were used as readouts.…”