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Nicotinic acid receptor abnormalities in human skin cancer: implications for a role in epidermal differentiation.

Bermudez Y, Benavente CA, Meyer RG, Coyle WR, Jacobson MK, Jacobson EL - PLoS ONE (2011)

Bottom Line: Receptor transcripts are greatly over-expressed in squamous cell cancers.In normal human primary and immortalized keratinocytes, nicotinic acid receptors show plasma membrane localization and functional G(i)-mediated signaling.The results of these studies justify future genetic and pharmacological intervention studies to define possible specific role(s) of nicotinic acid receptors in human skin homeostasis.

View Article: PubMed Central - PubMed

Affiliation: Arizona Cancer Center and Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, Arizona, United States of America.

ABSTRACT

Background: Chronic UV skin exposure leads to epidermal differentiation defects in humans that can be largely restored by pharmacological doses of nicotinic acid. Nicotinic acid has been identified as a ligand for the human G-protein-coupled receptors GPR109A and GPR109B that signal through G(i)-mediated inhibition of adenylyl cyclase. We have examined the expression, cellular distribution, and functionality of GPR109A/B in human skin and skin derived epidermal cells.

Results: Nicotinic acid increases epidermal differentiation in photodamaged human skin as judged by the terminal differentiation markers caspase 14 and filaggrin. Both GPR109A and GPR109B genes are transcribed in human skin and in epidermal keratinocytes, but expression in dermal fibroblasts is below limits of detection. Receptor transcripts are greatly over-expressed in squamous cell cancers. Receptor protein in normal skin is prominent from the basal through granular layers of the epidermis, with cellular localization more dispersive in the basal layer but predominantly localized at the plasma membrane in more differentiated epidermal layers. In normal human primary and immortalized keratinocytes, nicotinic acid receptors show plasma membrane localization and functional G(i)-mediated signaling. In contrast, in a squamous cell carcinoma derived cell line, receptor protein shows a more diffuse cellular localization and the receptors are nearly non-functional.

Conclusions: The results of these studies justify future genetic and pharmacological intervention studies to define possible specific role(s) of nicotinic acid receptors in human skin homeostasis.

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Related in: MedlinePlus

Localization of GPR109A/B protein expression in human skin.Immunohistochemistry (IHC) analyses were performed on paraffin-embedded human skin sections utilizing antibody against GPR109A/B. Panels A and B utilized Streptavidin Quantum Dot 605 Conjugates for detection. Panels C and D used FITC Goat Anti-Rabbit IgG for detection. Panel A: Representative immunostaining sample shown at 200× magnification. Panel B: Representative IHC sample shown at 400× magnification. Panels C and D: Representative IHC samples shown at 400× magnification in the absence (Panel C) or presence (Panel D) of competition with peptide used to generate the antibody. Abbreviations: SC, stratum corneum; SG, stratum granulosum; SS, stratum spinousum; SB, stratum basale. Size marker represents 2 microns.
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pone-0020487-g004: Localization of GPR109A/B protein expression in human skin.Immunohistochemistry (IHC) analyses were performed on paraffin-embedded human skin sections utilizing antibody against GPR109A/B. Panels A and B utilized Streptavidin Quantum Dot 605 Conjugates for detection. Panels C and D used FITC Goat Anti-Rabbit IgG for detection. Panel A: Representative immunostaining sample shown at 200× magnification. Panel B: Representative IHC sample shown at 400× magnification. Panels C and D: Representative IHC samples shown at 400× magnification in the absence (Panel C) or presence (Panel D) of competition with peptide used to generate the antibody. Abbreviations: SC, stratum corneum; SG, stratum granulosum; SS, stratum spinousum; SB, stratum basale. Size marker represents 2 microns.

Mentions: To determine the cellular localization of GPR109A/B in human skin, immunostaining analyses were performed. We observed that GPR109A/B are expressed from the basal layer through the spinous and granular layers of the epidermis and in the hair follicles of normal human skin (Fig. 4A). Higher magnification (Fig. 4B) reveals that GPR109A/B expression appears to be more evenly distributed throughout the cell in the basal cell layers of the epidermis and shows a more peripheral distribution in the spinous and granular layers where keratinocytes are in later stages of terminal differentiation. An alternative fluorescent tag, Fluorescein isothiocyanate (FITC), for detecting anti-peptide antibody binding is used in Fig. 4C to demonstrate that peptide used to generate the antibody effectively blocked binding in these tissues (Fig. 4D).


Nicotinic acid receptor abnormalities in human skin cancer: implications for a role in epidermal differentiation.

Bermudez Y, Benavente CA, Meyer RG, Coyle WR, Jacobson MK, Jacobson EL - PLoS ONE (2011)

Localization of GPR109A/B protein expression in human skin.Immunohistochemistry (IHC) analyses were performed on paraffin-embedded human skin sections utilizing antibody against GPR109A/B. Panels A and B utilized Streptavidin Quantum Dot 605 Conjugates for detection. Panels C and D used FITC Goat Anti-Rabbit IgG for detection. Panel A: Representative immunostaining sample shown at 200× magnification. Panel B: Representative IHC sample shown at 400× magnification. Panels C and D: Representative IHC samples shown at 400× magnification in the absence (Panel C) or presence (Panel D) of competition with peptide used to generate the antibody. Abbreviations: SC, stratum corneum; SG, stratum granulosum; SS, stratum spinousum; SB, stratum basale. Size marker represents 2 microns.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3105069&req=5

pone-0020487-g004: Localization of GPR109A/B protein expression in human skin.Immunohistochemistry (IHC) analyses were performed on paraffin-embedded human skin sections utilizing antibody against GPR109A/B. Panels A and B utilized Streptavidin Quantum Dot 605 Conjugates for detection. Panels C and D used FITC Goat Anti-Rabbit IgG for detection. Panel A: Representative immunostaining sample shown at 200× magnification. Panel B: Representative IHC sample shown at 400× magnification. Panels C and D: Representative IHC samples shown at 400× magnification in the absence (Panel C) or presence (Panel D) of competition with peptide used to generate the antibody. Abbreviations: SC, stratum corneum; SG, stratum granulosum; SS, stratum spinousum; SB, stratum basale. Size marker represents 2 microns.
Mentions: To determine the cellular localization of GPR109A/B in human skin, immunostaining analyses were performed. We observed that GPR109A/B are expressed from the basal layer through the spinous and granular layers of the epidermis and in the hair follicles of normal human skin (Fig. 4A). Higher magnification (Fig. 4B) reveals that GPR109A/B expression appears to be more evenly distributed throughout the cell in the basal cell layers of the epidermis and shows a more peripheral distribution in the spinous and granular layers where keratinocytes are in later stages of terminal differentiation. An alternative fluorescent tag, Fluorescein isothiocyanate (FITC), for detecting anti-peptide antibody binding is used in Fig. 4C to demonstrate that peptide used to generate the antibody effectively blocked binding in these tissues (Fig. 4D).

Bottom Line: Receptor transcripts are greatly over-expressed in squamous cell cancers.In normal human primary and immortalized keratinocytes, nicotinic acid receptors show plasma membrane localization and functional G(i)-mediated signaling.The results of these studies justify future genetic and pharmacological intervention studies to define possible specific role(s) of nicotinic acid receptors in human skin homeostasis.

View Article: PubMed Central - PubMed

Affiliation: Arizona Cancer Center and Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, Arizona, United States of America.

ABSTRACT

Background: Chronic UV skin exposure leads to epidermal differentiation defects in humans that can be largely restored by pharmacological doses of nicotinic acid. Nicotinic acid has been identified as a ligand for the human G-protein-coupled receptors GPR109A and GPR109B that signal through G(i)-mediated inhibition of adenylyl cyclase. We have examined the expression, cellular distribution, and functionality of GPR109A/B in human skin and skin derived epidermal cells.

Results: Nicotinic acid increases epidermal differentiation in photodamaged human skin as judged by the terminal differentiation markers caspase 14 and filaggrin. Both GPR109A and GPR109B genes are transcribed in human skin and in epidermal keratinocytes, but expression in dermal fibroblasts is below limits of detection. Receptor transcripts are greatly over-expressed in squamous cell cancers. Receptor protein in normal skin is prominent from the basal through granular layers of the epidermis, with cellular localization more dispersive in the basal layer but predominantly localized at the plasma membrane in more differentiated epidermal layers. In normal human primary and immortalized keratinocytes, nicotinic acid receptors show plasma membrane localization and functional G(i)-mediated signaling. In contrast, in a squamous cell carcinoma derived cell line, receptor protein shows a more diffuse cellular localization and the receptors are nearly non-functional.

Conclusions: The results of these studies justify future genetic and pharmacological intervention studies to define possible specific role(s) of nicotinic acid receptors in human skin homeostasis.

Show MeSH
Related in: MedlinePlus