Contributions of Nitric Oxide to AHR-Ligand-Mediated Keratinocyte Differentiation.

Carrie Hayes Sutter,Thomas R Sutter,Haley M Rainwater

doi:10.3390/ijms21165680

Carrie Hayes Sutter, Thomas R Sutter + Show 1 more

Open Access

https://doi.org/10.3390/ijms21165680

Copy DOI

Abstract

Activation of the aryl hydrocarbon receptor (AHR) in normal human epidermal keratinocytes (NHEKs) accelerates keratinocyte terminal differentiation through metabolic reprogramming and reactive oxygen species (ROS) production. Of the three NOS isoforms, NOS3 is significantly increased at both the RNA and protein levels by exposure to the very potent and selective ligand of the AHR, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Inhibition of NOS with the chemical N-nitro-l-arginine methyl ester (l-NAME) reversed TCDD-induced cornified envelope formation, an endpoint of terminal differentiation, as well as the expression of filaggrin (FLG), a marker of differentiation. Conversely, exposure to the NO-donor, S-nitroso-N-acetyl-DL-penicillamine (SNAP), increased the number of cornified envelopes above control levels and augmented the levels of cornified envelopes formed in response to TCDD treatment and increased the expression of FLG. This indicates that nitric oxide signaling can increase keratinocyte differentiation and that it is involved in the AHR-mediated acceleration of differentiation. As the nitrosylation of cysteines is a mechanism by which NO affects the structure and functions of proteins, the S-nitrosylation biotin switch technique was used to measure protein S-nitrosylation. Activation of the AHR increased the S-nitrosylation of two detected proteins of about 72 and 20 kD in size. These results provide new insights into the role of NO and protein nitrosylation in the process of epithelial cell differentiation, suggesting a role of NOS in metabolic reprogramming and the regulation of epithelial cell fate.

Highlights

Ligand activation of the aryl hydrocarbon receptor (AHR), a basic-helix-loop-helix, Per-ArntSim domain-containing transcription factor, is associated with diverse cellular, immunological, and toxicological effects [1]
Levels of NOS1 following 72 h of dimethyl sulfoxide (DMSO) as well as 72 h of TCDD were significantly lower than their respective 48 h levels, indicating that NOS1 gene expression decreased during keratinocyte differentiation
Our recent studies [10] demonstrate that AHR-mediated keratinocyte differentiation occurs through a series of metabolic reprogramming events including a decrease in glycolysis by the down-regulation of the glucose transporter, SLC2A1, and the glycolytic enzyme, ENO1

Summary

Introduction

Ligand activation of the aryl hydrocarbon receptor (AHR), a basic-helix-loop-helix, Per-ArntSim domain-containing transcription factor, is associated with diverse cellular, immunological, and toxicological effects [1]. Similar to repression of genes in the glycolytic pathway, activation of the AHR decreases the expression of numerous mitochondrial genes. This repression likely contributes to the decreased inner mitochondrial membrane potential, decreased ATP production and increased mitochondrial-specific reactive oxygen species (ROS) in the differentiating keratinocyte. As a regulator of glycolysis and mitochondrial function, the AHR metabolically reprograms the keratinocyte and alters its cell fate. This oxidative environment of the differentiating keratinocyte is conducive to the formation of a subset of ROS, reactive nitrogen species (RNS)

Methods

Results

Conclusion