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

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.

Crosstalk of the MAP3K1 and EGFR pathways mediates gene-environment interactions that disrupt developmental tissue closure

“…TCDD is known to activate the EGFR-ERK pathway and accelerate epithelial differentiation (Hansen et al, 1997, Sibilia and Wagner, 1995, Sutter et al, 2011, Kennedy et al, 2013, Sutter et al, 2020, Sutter et al, 2023, Fernandez-Salguero et al, 1996, Puga et al, 2005, Choi et al, 2006, Patel et al, 2006), an effect that may lead to promotion of precocious eyelid opening in postpartum pups (Theobald and Peterson, 1997, Gray et al, 1997, Miettinen et al, 2004, Dominey et al, 1993) and development of chloracne, a hyperkeratotic skin disorder, found in humans exposed to high dose TCDD (Sutter et al, 2011, Muenyi et al, 2014, Loertscher et al, 2001). This effect of TCDD, however, is insufficient to block embryonic lid closure.…”

Crosstalk of MAP3K1 and EGFR signaling mediates gene-environment interactions that block developmental tissue closure

“…EGFR signal is required for embryonic eyelid closure, as both the germline and OSE-specific Egfr KO cause basal epithelial cell hypoproliferation and a fully penetrable EOB defect ( 49 , 81 , 82 ). By activating the EGFR pathway, TCDD is shown to reduce the EOB phenotype of Egfr −/− pups by 50%, presumably through inducing ligands that activate other receptors of EGFR family to promote lid closure ( 83 , 84 ), and to promote precocious eyelid opening in postpartum pups through accelerating epithelial differentiation ( 85 , 86 , 87 ). Our data suggest that TCDD-induced EGFR activation is moderate and by itself is insufficient to alter the eyelid closure programs, because all TCDD-treated WT pups have normal lid closure ( 36 ).…”

Protective Effects of Ethanol Extract of Brazilian Green Propolis and Apigenin against Weak Ultraviolet Ray-B-Induced Barrier Dysfunction via Suppressing Nitric Oxide Production and Mislocalization of Claudin-1 in HaCaT Cells

“…The function of NO on skin health is controversial. The expression levels of NOS3 and NO production have been reported to be necessary for aryl hydrocarbon receptor-ligand-mediated keratinocyte differentiation [ 27 ]. In the macrophage, NO is required to possess antibacterial activity for the immune system [ 26 ].…”