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The δ-opioid receptor affects epidermal homeostasis via ERK-dependent inhibition of transcription factor POU2F3.

Neumann C, Bigliardi-Qi M, Widmann C, Bigliardi PL - J. Invest. Dermatol. (2014)

Bottom Line: Here, we show that δ-opioid receptor (DOPr) activation inhibits proliferation of human keratinocytes, resulting in decreased epidermal thickness in an organotypic skin model.We propose that DOPr signaling specifically activates the ERK 1/2 mitogen-activated protein kinase pathway to regulate keratinocyte functions.Complementing our earlier studies in DOPr-deficient mice, these data suggest that DOPr activation in human keratinocytes profoundly influences epidermal morphogenesis and homeostasis.

View Article: PubMed Central - PubMed

Affiliation: 1] Experimental Dermatology Laboratory, Institute of Medical Biology, A*STAR, Singapore [2] Doctoral School Faculty of Biology and Medicine, University of Lausanne, Dorigny, Switzerland.

ABSTRACT
Neuropeptides and their receptors are present in human skin, and their importance for cutaneous homeostasis and during wound healing is increasingly appreciated. However, there is currently a lack of understanding of the molecular mechanisms by which their signaling modulates keratinocyte function. Here, we show that δ-opioid receptor (DOPr) activation inhibits proliferation of human keratinocytes, resulting in decreased epidermal thickness in an organotypic skin model. DOPr signaling markedly delayed induction of keratin intermediate filament (KRT10) during in vitro differentiation and abolished its induction in the organotypic skin model. This was accompanied by deregulation of involucrin (IVL), loricrin, and filaggrin. Analysis of the transcription factor POU2F3, which is involved in regulation of KRT10, IVL, and profilaggrin expression, revealed a DOPr-mediated extracellular signal-regulated kinase (ERK)-dependent downregulation of this factor. We propose that DOPr signaling specifically activates the ERK 1/2 mitogen-activated protein kinase pathway to regulate keratinocyte functions. Complementing our earlier studies in DOPr-deficient mice, these data suggest that DOPr activation in human keratinocytes profoundly influences epidermal morphogenesis and homeostasis.

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δ-Opioid receptor (DOPr) is primarily expressed in suprabasal layers of normal human skin and exhibits Ca2+-dependent membrane localization in vitro. (a) In situ hybridization with digoxygenin-labeled antisense riboprobes showed prominent DOPr mRNA expression in spinous and granular layer keratinocytes (arrows) of normal human epidermis. Basal, sporadically, suprabasal layer keratinocytes (asterisk) express DOPr at lower levels. Bar = 50 μm. (b) Confocal fluorescence image stacks of DOPr (green) and desmoplakin (red) were obtained at 0.1 μm intervals in Z-section. Nuclei are counterstained with Hoechst (blue). N/TERT-1 cells overexpressing C-terminal green fluorescent protein (GFP)-tagged DOPr cultured in 0.09 mM Ca2+ medium exhibit an almost complete loss of desmosomal junctions while DOPr gets internalized (column 1). After change to 1.2 mM Ca2+ medium desmosomes gradually reform. DOPr starts to translocate to the membrane 15 minutes after Ca2+ addition and concentrates at the cell–cell junctions with progressive desmosome maturation. Bar = 10 μm.
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fig1: δ-Opioid receptor (DOPr) is primarily expressed in suprabasal layers of normal human skin and exhibits Ca2+-dependent membrane localization in vitro. (a) In situ hybridization with digoxygenin-labeled antisense riboprobes showed prominent DOPr mRNA expression in spinous and granular layer keratinocytes (arrows) of normal human epidermis. Basal, sporadically, suprabasal layer keratinocytes (asterisk) express DOPr at lower levels. Bar = 50 μm. (b) Confocal fluorescence image stacks of DOPr (green) and desmoplakin (red) were obtained at 0.1 μm intervals in Z-section. Nuclei are counterstained with Hoechst (blue). N/TERT-1 cells overexpressing C-terminal green fluorescent protein (GFP)-tagged DOPr cultured in 0.09 mM Ca2+ medium exhibit an almost complete loss of desmosomal junctions while DOPr gets internalized (column 1). After change to 1.2 mM Ca2+ medium desmosomes gradually reform. DOPr starts to translocate to the membrane 15 minutes after Ca2+ addition and concentrates at the cell–cell junctions with progressive desmosome maturation. Bar = 10 μm.

Mentions: We have previously documented the expression of DOPr mRNA in cultured human keratinocytes (Bigliardi-Qi et al., 2006, 2009), and have now gone on to confirm this expression in vivo by in situ hybridization on human corporal skin sections. Positive hybridization signals were detected in the stratum granulosum and, to a lesser extent, in the stratum spinosum. However, it was apparent that not all keratinocytes express the same amount of DOPr, reflected in the heterogeneous staining pattern (Figure 1a).


The δ-opioid receptor affects epidermal homeostasis via ERK-dependent inhibition of transcription factor POU2F3.

Neumann C, Bigliardi-Qi M, Widmann C, Bigliardi PL - J. Invest. Dermatol. (2014)

δ-Opioid receptor (DOPr) is primarily expressed in suprabasal layers of normal human skin and exhibits Ca2+-dependent membrane localization in vitro. (a) In situ hybridization with digoxygenin-labeled antisense riboprobes showed prominent DOPr mRNA expression in spinous and granular layer keratinocytes (arrows) of normal human epidermis. Basal, sporadically, suprabasal layer keratinocytes (asterisk) express DOPr at lower levels. Bar = 50 μm. (b) Confocal fluorescence image stacks of DOPr (green) and desmoplakin (red) were obtained at 0.1 μm intervals in Z-section. Nuclei are counterstained with Hoechst (blue). N/TERT-1 cells overexpressing C-terminal green fluorescent protein (GFP)-tagged DOPr cultured in 0.09 mM Ca2+ medium exhibit an almost complete loss of desmosomal junctions while DOPr gets internalized (column 1). After change to 1.2 mM Ca2+ medium desmosomes gradually reform. DOPr starts to translocate to the membrane 15 minutes after Ca2+ addition and concentrates at the cell–cell junctions with progressive desmosome maturation. Bar = 10 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4291683&req=5

fig1: δ-Opioid receptor (DOPr) is primarily expressed in suprabasal layers of normal human skin and exhibits Ca2+-dependent membrane localization in vitro. (a) In situ hybridization with digoxygenin-labeled antisense riboprobes showed prominent DOPr mRNA expression in spinous and granular layer keratinocytes (arrows) of normal human epidermis. Basal, sporadically, suprabasal layer keratinocytes (asterisk) express DOPr at lower levels. Bar = 50 μm. (b) Confocal fluorescence image stacks of DOPr (green) and desmoplakin (red) were obtained at 0.1 μm intervals in Z-section. Nuclei are counterstained with Hoechst (blue). N/TERT-1 cells overexpressing C-terminal green fluorescent protein (GFP)-tagged DOPr cultured in 0.09 mM Ca2+ medium exhibit an almost complete loss of desmosomal junctions while DOPr gets internalized (column 1). After change to 1.2 mM Ca2+ medium desmosomes gradually reform. DOPr starts to translocate to the membrane 15 minutes after Ca2+ addition and concentrates at the cell–cell junctions with progressive desmosome maturation. Bar = 10 μm.
Mentions: We have previously documented the expression of DOPr mRNA in cultured human keratinocytes (Bigliardi-Qi et al., 2006, 2009), and have now gone on to confirm this expression in vivo by in situ hybridization on human corporal skin sections. Positive hybridization signals were detected in the stratum granulosum and, to a lesser extent, in the stratum spinosum. However, it was apparent that not all keratinocytes express the same amount of DOPr, reflected in the heterogeneous staining pattern (Figure 1a).

Bottom Line: Here, we show that δ-opioid receptor (DOPr) activation inhibits proliferation of human keratinocytes, resulting in decreased epidermal thickness in an organotypic skin model.We propose that DOPr signaling specifically activates the ERK 1/2 mitogen-activated protein kinase pathway to regulate keratinocyte functions.Complementing our earlier studies in DOPr-deficient mice, these data suggest that DOPr activation in human keratinocytes profoundly influences epidermal morphogenesis and homeostasis.

View Article: PubMed Central - PubMed

Affiliation: 1] Experimental Dermatology Laboratory, Institute of Medical Biology, A*STAR, Singapore [2] Doctoral School Faculty of Biology and Medicine, University of Lausanne, Dorigny, Switzerland.

ABSTRACT
Neuropeptides and their receptors are present in human skin, and their importance for cutaneous homeostasis and during wound healing is increasingly appreciated. However, there is currently a lack of understanding of the molecular mechanisms by which their signaling modulates keratinocyte function. Here, we show that δ-opioid receptor (DOPr) activation inhibits proliferation of human keratinocytes, resulting in decreased epidermal thickness in an organotypic skin model. DOPr signaling markedly delayed induction of keratin intermediate filament (KRT10) during in vitro differentiation and abolished its induction in the organotypic skin model. This was accompanied by deregulation of involucrin (IVL), loricrin, and filaggrin. Analysis of the transcription factor POU2F3, which is involved in regulation of KRT10, IVL, and profilaggrin expression, revealed a DOPr-mediated extracellular signal-regulated kinase (ERK)-dependent downregulation of this factor. We propose that DOPr signaling specifically activates the ERK 1/2 mitogen-activated protein kinase pathway to regulate keratinocyte functions. Complementing our earlier studies in DOPr-deficient mice, these data suggest that DOPr activation in human keratinocytes profoundly influences epidermal morphogenesis and homeostasis.

Show MeSH