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Swan P, Johnson B, le Roux CW, Miras AD. Harnessing the melanocortin system in the control of food intake and glucose homeostasis. Peptides 2024; 179:171255. [PMID: 38834138 DOI: 10.1016/j.peptides.2024.171255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 05/27/2024] [Accepted: 05/28/2024] [Indexed: 06/06/2024]
Abstract
The central and peripheral melanocortin system, comprising of five receptors and their endogenous ligands, is responsible for a wide array of physiological functions such as skin pigmentation, sexual function and development, and inflammation. A growing body of both clinical and pre-clinical research is demonstrating the relevance of this system in metabolic health. Disruption of hypothalamic melanocortin signalling is the most common cause of monogenic obesity in humans. Setmelanotide, an FDA-approved analogue of alpha-melanocyte stimulating hormone (α-MSH) that functions by restoring central melanocortin signalling, has proven to be a potent pharmacological tool in the treatment of syndromic obesity. As the first effective therapy targeting the melanocortin system to treat metabolic disorders, its approval has sparked research to further harness the links between these melanocortin receptors and metabolic processes. Here, we outline the structure of the central and peripheral melanocortin system, discuss its critical role in the regulation of food intake, and review promising targets that may hold potential to treat metabolic disorders in humans.
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Affiliation(s)
- Patrick Swan
- Diabetes Research Centre, Biomedical Sciences Research Institute, Ulster University, Coleraine, Northern Ireland, United Kingdom; Diabetes Complications Research Centre, Conway Institute, University College Dublin, Dublin, Ireland.
| | - Brett Johnson
- Division of Diabetes, Endocrinology and Metabolism, Imperial College London, United Kingdom
| | - Carel W le Roux
- Diabetes Research Centre, Biomedical Sciences Research Institute, Ulster University, Coleraine, Northern Ireland, United Kingdom; Diabetes Complications Research Centre, Conway Institute, University College Dublin, Dublin, Ireland
| | - Alexander D Miras
- Diabetes Research Centre, Biomedical Sciences Research Institute, Ulster University, Coleraine, Northern Ireland, United Kingdom; Division of Diabetes, Endocrinology and Metabolism, Imperial College London, United Kingdom
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Logesh R, Prasad SR, Chipurupalli S, Robinson N, Mohankumar SK. Natural tyrosinase enzyme inhibitors: A path from melanin to melanoma and its reported pharmacological activities. Biochim Biophys Acta Rev Cancer 2023; 1878:188968. [PMID: 37657683 DOI: 10.1016/j.bbcan.2023.188968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 08/15/2023] [Accepted: 08/15/2023] [Indexed: 09/03/2023]
Abstract
The skin containing melanin pigment acts as a protective barrier and counteracts the UVR and other environmental stressors to maintain or restore disrupted cutaneous homeostasis. The production of melanin pigment is dependent on tyrosine levels. L-tyrosine and L-dihydroxyphenylalanine (L-DOPA) can serve both as a substrates and intermediates of melanin synthetic pathway and as inducers and positive regulators of melanogenesis. The biosynthesis of melanin is stimulated upon exposure to UVR, which can also stimulate local production of hormonal factors, which can stimulate melanoma development by altering the chemical properties of eu- and pheomelanin. The process of melanogenesis can be altered by several pathways. One involves activation of POMC, with the production of POMC peptides including MSH and ACTH, which increase intracellular cAMP levels, which activates the MITF, and helps to stimulate tyrosinase (TYR) expression and activity. Defects in OCA1 to 4 affects melanogenic activity via posttranslational modifications resulting in proteasomal degradation and reducing pigmentation. Further, altering, the MITF factor, helps to regulate the expression of MRGE in melanoma, and helps to increase the TYR glycosylation in ER. CRH stimulates POMC peptides that regulate melanogenesis and also by itself can stimulate melanogenesis. The POMC, P53, ACTH, MSH, MC1R, MITF, and 6-BH4 are found to be important regulators for pigmentation. Melanogenesis can affect melanoma behaviour and inhibit immune responses. Therefore, we reviewed natural products that would alter melanin production. Our special focus was on targeting melanin synthesis and TYR enzyme activity to inhibit melanogenesis as an adjuvant therapy of melanotic melanoma. Furthermore, this review also outlines the current updated pharmacological studies targeting the TYR enzyme from natural sources and its consequential effects on melanin production.
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Affiliation(s)
- Rajan Logesh
- Department of Pharmacognosy, JSS College of Pharmacy, JSS Academy of Higher Education and Research, Mysuru 570015, Karnataka, India.
| | - Sagar Rajendra Prasad
- Department of Pharmacognosy, Varadaraja Institute of Pharmaceutical Education and Research, Tumkur 572102, Karnataka, India
| | - Sandhya Chipurupalli
- Department of Pharmacology, JSS College of Pharmacy, JSS Academy of Higher Education and Research, Ooty, India
| | - Nirmal Robinson
- Cellular Stress and Immune Response Laboratory, Centre for Cancer Biology, University of South Australia, Adelaide, Australia
| | - Suresh Kumar Mohankumar
- Pharmacy, Swansea University Medical School, Singleton Park, Swansea University, Wales SA2 8PP, United Kingdom
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Moattari CR, Granstein RD. Neuropeptides and neurohormones in immune, inflammatory and cellular responses to ultraviolet radiation. Acta Physiol (Oxf) 2021; 232:e13644. [PMID: 33724698 DOI: 10.1111/apha.13644] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 02/26/2021] [Accepted: 03/02/2021] [Indexed: 12/16/2022]
Abstract
Humans are exposed to varying amounts of ultraviolet radiation (UVR) through sunlight. UVR penetrates into human skin leading to release of neuropeptides, neurotransmitters and neuroendocrine hormones. These messengers released from local sensory nerves, keratinocytes, Langerhans cells (LCs), mast cells, melanocytes and endothelial cells (ECs) modulate local and systemic immune responses, mediate inflammation and promote differing cell biologic effects. In this review, we will focus on both animal and human studies that elucidate the roles of calcitonin gene-related peptide (CGRP), substance P (SP), nerve growth factor (NGF), nitric oxide and proopiomelanocortin (POMC) derivatives in mediating immune and inflammatory effects of exposure to UVR as well as other cell biologic effects of UVR exposure.
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Abstract
PURPOSE OF REVIEW Patients seen at pediatric rheumatology are at increased risk of immediate and long-term consequences from sun exposure. The objective of this review is to build awareness of the need of sun protection in pediatric rheumatology patients. RECENT FINDINGS Sun exposure can lead to disease exacerbations in many rheumatic diseases. There is well documented literature linking the chronic use of immunosuppressants with long-term risk of skin cancer. Although there is a lack of literature in pediatric rheumatology addressing the need of sun protection in this patient population, the young age of patients, the nature of their disease and the treatments they receive, make them a high-risk population for the effects of the sun. SUMMARY Sun protection recommendations are outlined in the following manuscript, backed up by the rationale and biology of why it is important for pediatric rheumatology patients to be protected from the sun. The information reviewed in this article should be part of the education that all pediatric rheumatology patients should receive as part of their care.
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Binstock M, Hafeez F, Metchnikoff C, Arron S. Single‐nucleotide polymorphisms in pigment genes and nonmelanoma skin cancer predisposition: a systematic review. Br J Dermatol 2014; 171:713-21. [DOI: 10.1111/bjd.13283] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/20/2014] [Indexed: 12/20/2022]
Affiliation(s)
- M. Binstock
- Department of Dermatology University of California San Francisco San Francisco CA 94115 U.S.A
| | - F. Hafeez
- Department of Dermatology University of California San Francisco San Francisco CA 94115 U.S.A
| | - C. Metchnikoff
- Department of Dermatology University of California San Francisco San Francisco CA 94115 U.S.A
| | - S.T. Arron
- Department of Dermatology University of California San Francisco San Francisco CA 94115 U.S.A
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Inhibition of peroxisome proliferator-activated receptor gamma prevents the melanogenesis in murine B16/F10 melanoma cells. BIOMED RESEARCH INTERNATIONAL 2014; 2014:695797. [PMID: 25250328 PMCID: PMC4164518 DOI: 10.1155/2014/695797] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 08/14/2014] [Indexed: 11/17/2022]
Abstract
The purpose of this study was to investigate if PPARγ plays a role in the melanogenesis. B16/F10 cells were divided into five groups: control, melanin stimulating hormone (α-MSH), α-MSH+retinol, α-MSH+GW9662 (PPARγ antagonist), and GW9662. Cells in the control group were cultured in the Dulbecco's modified Eagle's medium (DMEM) for 48 hrs. To initiate the melanogenesis, cells in all α-MSH groups were cultured in medium containing α-MSH (10 nM) for 48 hrs. Cells were treated simultaneously with retinol (5 μM) in the α-MSH+retinol group. Instead of retinol, GW9662 (10 μM) was cocultured in the α-MSH+GW9662 group. Cells in the final group were cultured in the DMEM with GW9662. All the analyses were carried out 48 hours after treatments. The α-MSH was able to increase cell number, melanin production, and the activity of tyrosinase, the limiting enzyme in melanogenesis. These α-MSH-induced changes were prevented either by retinol or by GW9662. Further analyses of the activities of antioxidant enzymes including glutathione, catalase, and the superoxide dismutase (SOD) showed that α-MSH treatment raised the activity of SOD which was dependent on PPARγ level. According to our results, the α-MSH-induced melanogenesis was PPARγ dependent, which also modulated the expression of SOD.
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Dieudonné M, Ramesh KV. Modeling the interactions between MC2R and ACTH models from human. J Biomol Struct Dyn 2014; 33:770-88. [PMID: 24708442 DOI: 10.1080/07391102.2014.910475] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Melanocortin system is composed of four peptide hormones namely α-, β-, -γ, and adrenocorticotropic hormone (ACTH), derived from post-translational cleavage of a polypeptide precursor 'proopiomelanocortin (POMC).' Among these hormones, ACTH, a 38 amino acid residue peptide fragment is an important hormone as it is involved in steroid secretion. In addition to this, to cite a few, this hormone is also known to induce variety of other effects, such as alterations in motor/sexual behavior, improvement in memory, and anti-inflammatory effects. To date, five melanocortin receptors (MC1R-MC5R) have been characterized with tissue-specific expression patterns and different binding affinities for each of the melanocortin hormones to regulate various biological functions. In the present work, three-dimensional (3D) models of MC2R and ACTH from human have been predicted, followed by docking and molecular dynamics simulation. While the 3D model of MC2R receptor has been predicted through threading approach, structure of ACTH was built based on ab initio technique. The MC2R model was later successfully docked onto the ACTH structure. Molecular dynamics (MD) simulation for 20 ns was used to compute the binding free energy of MC2R with ACTH model under implicit solvent conditions.
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Affiliation(s)
- Mutangana Dieudonné
- a Department of Biotechnology , Centre for Post Graduate Studies, Jain University , 18/3, 9th Main, Jayanagar 3rd Block, Bangalore 560 011 , India
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Amaro-Ortiz A, Vanover JC, Scott TL, D'Orazio JA. Pharmacologic induction of epidermal melanin and protection against sunburn in a humanized mouse model. J Vis Exp 2013. [PMID: 24056496 DOI: 10.3791/50670] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Fairness of skin, UV sensitivity and skin cancer risk all correlate with the physiologic function of the melanocortin 1 receptor, a Gs-coupled signaling protein found on the surface of melanocytes. Mc1r stimulates adenylyl cyclase and cAMP production which, in turn, up-regulates melanocytic production of melanin in the skin. In order to study the mechanisms by which Mc1r signaling protects the skin against UV injury, this study relies on a mouse model with "humanized skin" based on epidermal expression of stem cell factor (Scf). K14-Scf transgenic mice retain melanocytes in the epidermis and therefore have the ability to deposit melanin in the epidermis. In this animal model, wild type Mc1r status results in robust deposition of black eumelanin pigment and a UV-protected phenotype. In contrast, K14-Scf animals with defective Mc1r signaling ability exhibit a red/blonde pigmentation, very little eumelanin in the skin and a UV-sensitive phenotype. Reasoning that eumelanin deposition might be enhanced by topical agents that mimic Mc1r signaling, we found that direct application of forskolin extract to the skin of Mc1r-defective fair-skinned mice resulted in robust eumelanin induction and UV protection (1). Here we describe the method for preparing and applying a forskolin-containing natural root extract to K14-Scf fair-skinned mice and report a method for measuring UV sensitivity by determining minimal erythematous dose (MED). Using this animal model, it is possible to study how epidermal cAMP induction and melanization of the skin affect physiologic responses to UV exposure.
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Schallreuter KU, Salem MMAEL, Hasse S, Rokos H. The redox--biochemistry of human hair pigmentation. Pigment Cell Melanoma Res 2010; 24:51-62. [PMID: 20958953 DOI: 10.1111/j.1755-148x.2010.00794.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The biochemistry of hair pigmentation is a complex field involving a plethora of protein and peptide mechanisms. The in loco factory for melanin formation is the hair follicle melanocyte, but it is common knowledge that melanogenesis results from a fine tuned concerted interaction between the cells of the entire dermal papilla in the anagen hair follicle. The key enzyme is tyrosinase to initiate the active pigmentation machinery. Hence, an intricate understanding from transcription of mRNA to enzyme activity, including enzyme kinetics, substrate supply, optimal pH, cAMP signaling, is a must. Moreover, the role of reactive oxygen species on enzyme regulation and functionality needs to be taken into account. So far our knowledge on the entire hair cycle relies on the murine model of the C57BL/6 mouse. Whether this data can be translated into humans still needs to be shown. This article aims to focus on the effect of H(2)O(2)-redox homeostasis on hair follicle pigmentation via tyrosinase, its substrate supply and signal transduction as well as the role of methionine sulfoxide repair via methionine sulfoxide reductases A and B (MSRA and B).
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Affiliation(s)
- Karin U Schallreuter
- Institute for Pigmentary Disorders in Association with EM Arndt University Greifswald, Biotechnikum, Greifswald, Germany.
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Kuhn A, Ruland V, Bonsmann G. Photosensitivity, phototesting, and photoprotection in cutaneous lupus erythematosus. Lupus 2010; 19:1036-46. [DOI: 10.1177/0961203310370344] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cutaneous lupus erythematosus (CLE) is a heterogeneous autoimmune disease involving well-defined skin lesions that can be categorized as acute CLE (ACLE), subacute CLE (SCLE), chronic CLE (CCLE), or intermittent CLE (ICLE). It is commonly accepted that ultraviolet (UV) exposure can induce and exacerbate skin lesions in patients with certain subtypes of CLE. Phototesting with UVA and UVB irradiation using a standardized protocol has proven to be a reliable model to study photosensitivity in CLE and to analyse the underlying pathomechanisms of the disease. In addition to UV-mediated induction of apoptosis, the molecular and cellular factors that may underlie the abnormal long-lasting photoreactivity in CLE include mediators of inflammation such as cytokines and chemokines, inducible nitric oxide (NO) synthase (iNOS), and cellular adhesion molecules. The photosensitivity associated with CLE requires education of the patient about avoidance of excessive sun exposure, continuous photoprotection through physical measures such as protective clothing, and daily application of broad-spectrum sunscreens. Novel approaches to UV-protection, such as alpha-MSH or thymidine dinucleotides, might also have an impact on photosensitivity in patients with CLE. In this review, we summarize the current knowledge about photosensitivity in patients with CLE, including an overview of standardized phototesting procedures, possible molecular pathomechanisms, and photoprotection. Lupus (2010) 19, 1036—1046.
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Affiliation(s)
- A. Kuhn
- Department of Dermatology, University of Münster, Münster, Germany,
| | - V. Ruland
- Department of Dermatology, University of Münster, Münster, Germany
| | - G. Bonsmann
- Department of Dermatology, University of Münster, Münster, Germany
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Abdel-Malek ZA, Kadekaro AL, Swope VB. Stepping up melanocytes to the challenge of UV exposure. Pigment Cell Melanoma Res 2010; 23:171-86. [PMID: 20128873 DOI: 10.1111/j.1755-148x.2010.00679.x] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Exposure to solar ultraviolet radiation (UV) is the main etiological factor for skin cancer, including melanoma. Cutaneous pigmentation, particularly eumelanin, afforded by melanocytes is the main photoprotective mechanism, as it prevents UV-induced DNA damage in the epidermis. Therefore, maintaining genomic stability of melanocytes is crucial for prevention of melanoma, as well as keratinocyte-derived basal and squamous cell carcinoma. A critical independent factor for preventing melanoma is DNA repair capacity. The response of melanocytes to UV is mediated mainly by a network of paracrine factors that not only activate melanogenesis, but also DNA repair, anti-oxidant, and survival pathways that are pivotal for maintenance of genomic stability and prevention of malignant transformation or apoptosis. However, little is known about the stress response of melanocytes to UV and the regulation of DNA repair pathways in melanocytes. Unraveling these mechanisms might lead to strategies to prevent melanoma, as well as non-melanoma skin cancer.
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Affiliation(s)
- Zalfa A Abdel-Malek
- Department of Dermatology, University of Cincinnati Collage of Medicine, Cincinnati, OH, USA.
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12
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Garcin G, Le Gallic L, Stoebner PE, Guezennec A, Guesnet J, Lavabre-Bertrand T, Martinez J, Meunier L. Constitutive Expression of MC1R in HaCaT Keratinocytes Inhibits Basal and UVB-induced TNF-α Production. Photochem Photobiol 2009; 85:1440-50. [DOI: 10.1111/j.1751-1097.2009.00598.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Rauch I, Holzmeister S, Kofler B. Anti-Candida activity of alpha-melanocyte-stimulating hormone (alpha-MSH) peptides. J Leukoc Biol 2008; 85:371-2; author reply 373. [PMID: 19092131 DOI: 10.1189/jlb.1008614] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Previously, alpha-MSH, a 13-amino acid neuropeptide and the tripeptide alpha-MSH have been shown to possess potent antimicrobial properties. We performed microplate based growth inhibition assays on C. albicans with alpha-MSH, but could not observe any growth inhibiting effect. Repeating the originally published assay with different C. albicans strains, we detected a mild growth inhibiting effect of 100 microM alpha-MSH, but again no effect of alpha-MSH.
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Grimbaldeston MA, Green A, Darlington S, Robertson BO, Marshman G, Finlay-Jones JJ, Hart PH. Susceptibility to Basal Cell Carcinoma is Associated with High Dermal Mast Cell Prevalence in Non-sun-exposed Skin for an Australian Population¶. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2003)0780633stbcci2.0.co2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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15
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Spencer JD, Gibbons NCJ, Rokos H, Peters EMJ, Wood JM, Schallreuter KU. Oxidative stress via hydrogen peroxide affects proopiomelanocortin peptides directly in the epidermis of patients with vitiligo. J Invest Dermatol 2007; 127:411-20. [PMID: 16946714 DOI: 10.1038/sj.jid.5700538] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The human skin holds the capacity for autocrine processing of the proopiomelanocortin (POMC)-derived peptides. Recent data demonstrated the presence and functionality of ACTH, alpha- and beta-melanocyte-stimulating hormone (MSH), and beta-endorphin in the regulation of skin pigmentation, and a role has been put forward for alpha-MSH as an effective antioxidant. In patients with vitiligo, decreased epidermal POMC processing and low alpha-MSH levels were documented previously. These patients accumulate hydrogen peroxide (H2O2) in the 10(-3) M range in their epidermis. Therefore, we examined the involvement of H2O2 on POMC-derived peptides as possible targets for oxidation by this reactive oxygen species. To address this, we employed immunofluorescence labelling, dot blot analysis, Fourier transform Raman spectroscopy, functionality studies, and computer simulation of the peptide structures. We demonstrate H2O2-mediated oxidation of epidermal ACTH, alpha-MSH, and beta-endorphin in vitiligo owing to oxidation of methionine residues in the sequences of these peptides. Moreover, we show that oxidized beta-endorphin loses its function in the promotion of pigmentation in melanocytes. These changes are reversible upon the reduction of H2O2 levels by a pseudocatalase PC-KUS. Moreover, oxidation of alpha-MSH can be prevented by the formation of a 1:1 complex with the abundant cofactor (6R)-L-erythro-5,6,7,8-tetrahydrobiopterin. Thus, using vitiligo, we demonstrate that H2O2 can affect pigmentation via epidermal POMC peptide redox homeostasis.
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Affiliation(s)
- Jennifer D Spencer
- Clinical and Experimental Dermatology/Department of Biomedical Sciences, University of Bradford, Bradford, UK
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Abstract
Ultraviolet radiation (UV), in particular the UVB range, suppresses the immune system in several ways. UVB inhibits antigen presentation, induces the release of immunosuppressive cytokines and causes apoptosis of leukocytes. UVB, however, does not cause general immunosuppression but rather inhibits immune reactions in an antigen-specific fashion. Application of contact allergens onto UV-exposed skin does not cause sensitization but induces antigen-specific tolerance since such an individual cannot be sensitized against the very same allergen later, although sensitization against other allergens is not impaired. This specific immunosuppression is mediated by antigen-specific suppressor/ regulatory T cells. UVB-induced DNA damage is a major molecular trigger of UV-mediated immunosuppression. Reduction of DNA damage mitigates UV-induced immunosuppression. Likewise interleukin-12 which exhibits the capacity to reduce DNA damage can prevent UV-induced immunosuppression and even break tolerance. Presentation of the antigen by UV-damaged Langerhans cells in the lymph nodes appears to be an essential requirement for the development of regulatory T cells. Studies addressing the molecular mechanisms underlying UV-induced immunosuppression will contribute to a better understanding how UV acts as a pathogen but on the other hand can be also used as a therapeutic tool.
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Affiliation(s)
- Thomas Schwarz
- Department of Dermatology, University Kiel, Kiel, Germany.
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Todorovic A, Haskell-Luevano C. A review of melanocortin receptor small molecule ligands. Peptides 2005; 26:2026-36. [PMID: 16051395 DOI: 10.1016/j.peptides.2004.11.024] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2004] [Accepted: 11/18/2004] [Indexed: 11/22/2022]
Abstract
The melanocortin system (MC) is implicated in the regulation of a variety of physiological pathways including pigmentation, steroid function, energy homeostasis, food intake, obesity, cardiovascular, sexual function, and normal gland regulation. The melanocortin system consists of five receptors identified to date (MC1-5R), melanocortin agonists derived from the pro-opiomelanocortin prohormone (POMC) and two naturally existing antagonists. Melanocortin receptor ligand structure-activity studies have been performed since the 1960s, primarily focused on the pigmentation aspect of physiology. During the 1990s, the melanocortin-4 receptor was identified to play a significant physiological role in the regulation of both food intake and obesity. Subsequently, a concerted drug design effort has focused on the design and discovery of melanocortin receptor small molecules. Herein, we present an overview of melanocortin receptor heterocyclic small molecules.
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Affiliation(s)
- Aleksandar Todorovic
- Department of Medicinal Chemistry, University of Florida, P.O. Box 100485, Gainesville, FL 32610, USA
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18
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Neuroendocrine Regulation of Natural Immunity. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/s1567-7443(05)80017-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Schiller M, Brzoska T, Böhm M, Metze D, Scholzen TE, Rougier A, Luger TA. Solar-Simulated Ultraviolet Radiation-Induced Upregulation of the Melanocortin-1 Receptor, Proopiomelanocortin, and α-Melanocyte-Stimulating Hormone in Human Epidermis In Vivo. J Invest Dermatol 2004; 122:468-76. [PMID: 15009732 DOI: 10.1046/j.0022-202x.2004.22239.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Ultraviolet light is one of the most crucial environmental factors with regard to its capacity to induce skin cancer, premature aging of the skin, and immunosuppression. Although ultraviolet directly affects the function of epidermal cells, many of these effects are mediated by induction of cytokines, growth factors, and neuropeptides, such as alpha-melanocyte-stimulating hormone. Recently, in addition to its well-known pigmentation inducing activity, a strong anti-inflammatory as well as an immunomodulatory potential of alpha-melanocyte-stimulating hormone has been recognized. The aim of this study was to determine, whether ultraviolet irradiation affects the expression of both alpha-melanocyte-stimulating hormone and the melanocortin-1 receptor in human epidermis in vivo. The volar aspects of the forearms were exposed to twice the minimal erythema dose of solar-simulating radiation. Three, 6, and 24 h after irradiation, the proopiomelanocortin and interleukin-10 mRNA levels in suction blister induced epidermal sheets were considerably upregulated as detected by semiquantitative reverse transcription-polymerase chain reaction. Furthermore, alpha-melanocyte-stimulating hormone and interleukin-10 protein levels in blister fluids were significantly increased 24 h after ultraviolet irradiation, an effect that could be abolished by application of the broad-spectrum sunscreen Anthélios XL prior to ultraviolet (solar-simulating radiation) exposure. In addition, enhanced melanocortin-1 receptor mRNA and receptor protein expression upon solar-simulating radiation was ascertained by reverse transcription-polymerase chain reaction and immunohistochemistry of the epidermal sheets, respectively. Proopiomelanocortin-derived neuropeptides, such as alpha-melanocyte-stimulating hormone may therefore play an important part in modulating ultraviolet-induced inflammation.
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Affiliation(s)
- Meinhard Schiller
- Department of Dermatology and Ludwig Boltzmann Institute for Cell Biology and Immunobiology of the Skin, University of Münster, Muenster, Germany
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Eves P, Haycock J, Layton C, Wagner M, Kemp H, Szabo M, Morandini R, Ghanem G, García-Borrón JC, Jiménez-Cervantes C, Mac Neil S. Anti-inflammatory and anti-invasive effects of alpha-melanocyte-stimulating hormone in human melanoma cells. Br J Cancer 2004; 89:2004-15. [PMID: 14612916 PMCID: PMC2394449 DOI: 10.1038/sj.bjc.6601349] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
α-Melanocyte stimulating hormone (α-MSH) is known to have pleiotrophic functions including pigmentary, anti-inflammatory, antipyretic and immunoregulatory roles in the mammalian body. It is also reported to influence melanoma invasion with levels of α-, β- and γ-MSH correlated clinically with malignant melanoma development, but other studies suggest α-MSH acts to retard invasion. In the present study, we investigated the action of α-MSH on three human melanoma cell lines (HBL, A375-SM and C8161) differing in metastatic potential. α-melanocyte-simulating hormone reduced invasion through fibronectin and also through a human reconstructed skin composite model for the HBL line, and inhibited proinflammatory cytokine-stimulated activation of the NF-κB transcription factor. However, A375-SM and C8161 cells did not respond to α-MSH. Immunofluorescent microscopy and Western blotting identified melanocortin-1 receptor (MC-1R) expression for all three lines and MC-2R on HBL and A375-SM lines. Receptor binding identified a similar affinity for α-MSH for all three lines with the highest number of binding sites on HBL cells. Only the HBL melanoma line demonstrated a detectable cyclic adenosine monophosphate (cAMP) response to α-MSH, although all three lines responded to acute α-MSH addition (+(−)-N6-(2-phenylisopropyl)-adenosine (PIA)) with an elevation in intracellular calcium. The nonresponsive lines displayed MC-1R polymorphisms (C8161, Arg (wt) 151/Cys 151; A375-SM, homozygous Cys 151), whereas the HBL line was wild type. Stable transfection of the C8161 line with wild-type MC-1R produced cells whose invasion was significantly inhibited by α-MSH. From this data, we conclude that α-MSH can reduce melanoma cell invasion and protect cells against proinflammatory cytokine attack in cells with the wild-type receptor (HBL).
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Affiliation(s)
- P Eves
- University Section of Medicine, Division of Clinical Sciences, Northern General Hospital, Sheffield S5 7AU, UK
| | - J Haycock
- Department of Engineering Materials, University of Sheffield, Mappin Street, Sheffield S1 3JD, UK
| | - C Layton
- Department of Histopathology, Northern General Hospital Trust, Sheffield S5 7AU, UK
| | - M Wagner
- University Section of Medicine, Division of Clinical Sciences, Northern General Hospital, Sheffield S5 7AU, UK
| | - H Kemp
- University Section of Medicine, Division of Clinical Sciences, Northern General Hospital, Sheffield S5 7AU, UK
| | - M Szabo
- Department of Engineering Materials, University of Sheffield, Mappin Street, Sheffield S1 3JD, UK
| | - R Morandini
- Laboratory of Oncology and Experimental Surgery, Institut Bordet, Université Libre de Bruxelles, Belgium
| | - G Ghanem
- Laboratory of Oncology and Experimental Surgery, Institut Bordet, Université Libre de Bruxelles, Belgium
| | - J C García-Borrón
- Department of Biochemistry and Molecular Biology, School of Medicine, University of Murcia, Apto 4021, 30100 Espinardo, Murcia, Spain
| | - C Jiménez-Cervantes
- Department of Biochemistry and Molecular Biology, School of Medicine, University of Murcia, Apto 4021, 30100 Espinardo, Murcia, Spain
| | - S Mac Neil
- University Section of Medicine, Division of Clinical Sciences, Northern General Hospital, Sheffield S5 7AU, UK
- Department of Engineering Materials, University of Sheffield, Mappin Street, Sheffield S1 3JD, UK
- University Section of Medicine, Division of Clinical Sciences (North), Northern General Hospital, Sheffield S5 7AU, UK. E-mail:
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21
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Friedrich M, Holzmann R, Sterry W, Wolk K, Truppel A, Piazena H, Schonbein C, Sabat R, Asadullah K. Ultraviolet B Radiation-Mediated Inhibition of Interferon-γ-Induced Keratinocyte Activation Is Independent of Interleukin-10 and Other Soluble Mediators But Associated with Enhanced Intracellular Suppressors of Cytokine-Signaling Expression. J Invest Dermatol 2003; 121:845-52. [PMID: 14632204 DOI: 10.1046/j.1523-1747.2003.12482.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Ultraviolet irradiation represents a well-established treatment modality for inflammatory skin diseases. The aim of this study was to investigate the mechanisms of ultraviolet B radiation-induced keratinocyte insensitivity towards interferon-gamma. Flow cytometric analyses indicated that ultraviolet B radiation temporarily inhibits the interferon-gamma-induced activation of primary keratinocyte and HaCaT cells as measured by reduced intercellular adhesion molecule-1 (CD54) and HLA-DR upregulation. Western blot experiments have suggested that this is mediated by the ultraviolet B radiation-induced inhibition of signal transduction and transcription factor-1 phosphorylation. Neither interleukin-10 neutralization nor interleukin-10 addition had any effect on the ultraviolet B radiation-induced inhibition of interferon-gamma induced intercellular adhesion molecule-1 expression. Furthermore, the supernatant from ultraviolet B-irradiated cells failed to inhibit the interferon-gamma-induced CD54 and HLA-DR upregulation in nonradiated HaCaT cells. Moreover, irradiated cells from whom the supernatant was withdrawn 4 h after irradiation still showed a diminished interferon-gamma-induced response after 24 h. Thus, not soluble but intracellular factors might be involved in the ultraviolet B radiation-induced inhibition of interferon-gamma-induced keratinocyte activation. Therefore, we analyzed the expression of members of suppressors of cytokine-signaling (SOCS) molecules using real-time polymerase chain reaction. We found a fast and strong upregulation of SOCS1 and SOCS3 but not of SOCS2 after ultraviolet B radiation. Similarly, ultraviolet B radiation induced the expression of these particular SOCS molecules in lesional psoriatic skin. As SOCS molecules are known inhibitors of signal transduction and transcription factor phosphorylation, which is essential for interferon-gamma-induced intercellular adhesion molecule-1 and HLA-DR upregulation, this may explain the interferon-gamma unresponsiveness after ultraviolet B radiation.
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Affiliation(s)
- Markus Friedrich
- Department for Dermatology and Allergology, Medical School Charité, Humboldt University Berlin, Berlin, Germany
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22
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Abstract
Much is known regarding the deleterious effects of ultraviolet radiation (UV) on the skin. As more epidemiologic and basic research continues to characterize the impact of sun exposure and other sources of UV radiation upon the development of cutaneous neoplasm and a variety of photosensitive dermatoses, it is crucial for the dermatologist to promote sun protection among his/her patients as well as the primary care physician who has a greater reach of the community than the skin specialist. Practical steps to achieve optimal sun protection include avoidance of UV radiation, avoidance of photosensitizing drugs, use of photo-protective clothing, and diligent application of broad-spectrum sunscreens. In recent years, novel agents and experimental modalities with the potential to offer enhanced protective effects against deleterious sequelae of sun exposure have been elucidated, e.g. antioxidants, alpha-MSH, polyphenol in green teas, genistein, NF-kB decoy oligodeoxynucleotides, pTpT vaccination, and IL-12. As these new photo-protective tools are being developed by scientists around the world, greater concerted effort is needed to engage public health officials and the media to promote sun protection awareness throughout the general public.
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Affiliation(s)
- William W Ting
- Department of Dermatology, University of Iowa College of Medicine, and University of Iowa Health Care, IA 52242, USA
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23
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Abstract
The melanocortin system consists of melanocortin peptides derived from the proopiomelanocortin gene, five melanocortin receptors, two endogenous antagonists, and two ancillary proteins. This review provides an abbreviated account of the basic biochemistry, pharmacology, and physiology of the melanocortin system and highlights progress made in four areas. In particular, recent pharmacological and genetic studies have affirmed the role of melanocortins in pigmentation, inflammation, energy homeostasis, and sexual function. Development of selective agonists and antagonists is expected to further facilitate the investigation of these complex physiological functions and provide an experimental basis for new pharmacotherapies.
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Affiliation(s)
- Ira Gantz
- Department of Surgery, University of Michigan Medical School, Ann Arbor, Michigan 48109-0682, USA.
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24
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Grimbaldeston MA, Green A, Darlington S, Robertson BO, Marshman G, Finlay-Jones JJ, Hart PH. Susceptibility to Basal Cell Carcinoma is Associated with High Dermal Mast Cell Prevalence in Non–sun-exposed Skin for an Australian Population¶. Photochem Photobiol 2003; 78:633-9. [PMID: 14743874 DOI: 10.1562/0031-8655(2003)078<0633:stbcci>2.0.co;2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In a Danish population, basal cell carcinoma (BCC) patients have a higher dermal mast cell prevalence in buttock skin than controls. This finding was supported by a functional link in mice between histamine-staining dermal mast cells and the extent of susceptibility to UV-B-induced systemic immunomodulation. It was important to confirm that this association was maintained in an Australian population with very different ancestry and sun exposure patterns. Australian BCC patients (n = 26) had significantly higher densities of mast cells in the dermis of buttock skin than control subjects (n = 25) (P = 0.0003, Mann-Whitney U-test). However, this correlation was lost at the sun-exposed site of the hand (P = 0.547, Mann-Whitney U-test). To further evaluate whether a relationship exists between dermal mast cell prevalence in sun-exposed skin and incidence of BCC in a larger study, biopsies of dorsal hand skin were obtained from an age-stratified random sample of 166 Queensland subjects, together with the 51 South Australian subjects, and dermal mast cell prevalence was quantified. Older subjects (over the median age of 42 years) had a greater incidence of BCC development (P = 0.0001, chi-square test) and significantly higher mast cell densities in hand skin (P = 0.0001, chi-square test) than younger subjects. However, mast cell density in sun-exposed hand skin was not significantly associated with BCC incidence. Finally, cellular expression of c-kit correlated with mast cell prevalence in non-sun-exposed skin, thereby implicating the stem cell factor-c-kit axis in the intrinsic mechanisms that regulate prevalence. These results show that high prevalence of dermal mast cells in buttock skin but not hand is associated with BCC development in an Australian population.
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Affiliation(s)
- Michele A Grimbaldeston
- Department of Microbiology and Infectious Diseases, School of Medicine and Flinders Medical Research Institute, Flinders University, Adelaide, Australia
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25
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Seiffert K, Granstein RD. Neuropeptides and neuroendocrine hormones in ultraviolet radiation-induced immunosuppression. Methods 2002; 28:97-103. [PMID: 12231193 DOI: 10.1016/s1046-2023(02)00214-1] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Exposure of the skin to ultraviolet radiation (UVR) can lead to deleterious effects such as sunburn, photoaging, and the development of skin cancer. UVR has also been shown to reduce local and systemic immune responses in humans and animals. In the recent past it has become clear that neuropeptides mediate some of the effects of UVR-induced immunosuppression. Among the neuropeptides released from cutaneous nerves after exposure to UVR, calcitonin gene-related peptide (CGRP) has been examined most extensively. It appears to lead to a reduction of contact hypersensitivity by inducing mast cells to degranulate and thus release tumor necrosis factor alpha (TNF-alpha) and, most likely, interleukin (IL)-10. Nitric oxide, which is coreleased with CGRP, seems to also play a role in immunosuppression through a yet undiscovered mechanism of action, while substance P may have counterregulatory effects. New evidence suggests that the release of neuropeptides from cutaneous sensory c-fibers after UVR is induced by keratinocyte-derived nerve growth factor. UVR can also induce epidermal and some dermal cells, such as melanocytes, keratinocytes, and dermal microvascular epithelial cells, to produce proopiomelanocortin (POMC) and its derivatives. The POMC product alpha-melanocyte-stimulating hormone (alpha-MSH) has been implicated in suppression of contact hypersensitivity and induction of hapten-specific tolerance, most likely by inducing keratinocytes and monocytes to produce the anti-inflammatory cytokine IL-10. Other POMC derivatives have not yet been investigated with regard to a possible role in UVR-induced effects on immunity.
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Affiliation(s)
- Kristina Seiffert
- Department of Dermatology, Joan and Sanford I. Weill Medical College of Cornell University, New York, NY 10021, USA
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26
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Bastiaens MT, ter Huurne JA, Kielich C, Gruis NA, Westendorp RG, Vermeer BJ, Bavinck JN. Melanocortin-1 receptor gene variants determine the risk of nonmelanoma skin cancer independently of fair skin and red hair. Am J Hum Genet 2001; 68:884-94. [PMID: 11254446 PMCID: PMC1275642 DOI: 10.1086/319500] [Citation(s) in RCA: 442] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2000] [Accepted: 01/22/2001] [Indexed: 11/03/2022] Open
Abstract
Melanocortin-1 receptor (MC1R) gene variants are associated with fair skin and red hair and, independently of these, with cutaneous malignant melanoma. The association of MC1R gene variants with nonmelanoma skin cancer is largely unknown. A total of 838 subjects were included in the present study: 453 patients with nonmelanoma skin cancer and 385 subjects with no skin cancer. The coding sequence of the human MC1R gene was tested using single-stranded conformation polymorphism analysis followed by sequencing of unknown variants. Risk of skin cancer dependent on the various MC1R gene variants was estimated using the exposure odds ratio. We investigated whether subjects with MC1R variant alleles were at increased risk of developing nonmelanoma skin cancer and, if so, whether this increased risk was mediated by fair skin and red hair. A total of 27 MC1R gene variants were found. The number of carriers of one, two, or three MC1R gene variants was 379 (45.2%), 208 (24.8%), and 7 (0.9%), respectively. A strong association between MC1R gene variants and fair skin and red hair was established, especially the variants Arg151Cys and Arg160Trp (P < .0001). Carriers of two variant alleles were at increased risk for developing cutaneous squamous cell carcinoma (odds ratio 3.77; 95% confidence interval [CI] 2.11-6.78), nodular basal cell carcinoma (odds ratio 2.26; 95% CI 1.45-3.52), and superficial multifocal basal cell carcinoma (odds ratio 3.43; 95% CI 1.92-6.15), compared with carriers of two wild-type alleles. Carriers of one variant allele had half the risk. The highest relative risks of nonmelanoma skin cancer were found in carriers of the Asp84Glu, His260Pro, and Asp294His variant alleles, and the risk was only slightly lower for carriers of the Val60Leu, Val92Met, Arg142His, Arg151Cys, and Arg160Trp variant alleles. When subjects were stratified by skin type and hair color, analysis showed that these factors did not materially change the relative risks. These findings indicate that MC1R gene variants are important independent risk factors for nonmelanoma skin cancer.
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Affiliation(s)
- M T Bastiaens
- Department of Dermatology, Leiden University Medical Centre, 2300 RC Leiden, The Netherlands
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27
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Scholzen TE, Kalden DH, Brzoska T, Fisbeck T, Fastrich M, Schiller M, Böhm M, Schwarz T, Armstrong CA, Ansel JC, Luger TA. Expression of proopiomelanocortin peptides in human dermal microvascular endothelial cells: evidence for a regulation by ultraviolet light and interleukin-1. J Invest Dermatol 2000; 115:1021-8. [PMID: 11121136 DOI: 10.1046/j.1523-1747.2000.00174.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Proopiomelanocortin peptides such as alpha-melanocyte-stimulating hormone and adrenocorticotropin are expressed in the epidermal and dermal compartment of the skin after noxious stimuli and are recognized as modulators of immune and inflammatory reactions. Human dermal microvascular endothelial cells mediate leukocyte-endothelial interactions during cutaneous inflammation by the expression of cellular adhesion molecules and cytokines such as interleukin-1. This study addresses the hypothesis that human dermal microvascular endothelial cells express both proopiomelanocortin and prohormone convertases, which are required to generate proopiomelanocortin peptides. Semiquantitative reverse transcriptase polymerase chain reaction and northern blot studies revealed a constitutive expression of proopiomelanocortin mRNA by human dermal microvascular endothelial cells in vitro that was time- and concentration-dependently upregulated by interleukin-1 beta. Furthermore, irradiation of human dermal microvascular endothelial cells with ultraviolet A1 (30J per cm(2)) or ultraviolet B (12.5 mJ per cm(2)) enhanced proopiomelanocortin expression as well as the production and release of the proopiomelanocortin peptides adrenocorticotropin and alpha-melanocyte-stimulating hormone. In addition to proopiomelanocortin, prohormone convertase 1 mRNA expression was detected by reverse transcriptase polymerase chain reaction in unstimulated human dermal microvascular endothelial cells and was augmented after exposure to alpha-melanocyte- stimulating hormone, interleukin-1 beta, or irradiation with ultraviolet. These findings demonstrate that human dermal microvascular endothelial cells express proopiomelanocortin and prohormone convertase 1 required for the generation of adrenocorticotropin. Additionally, human dermal microvascular endothelial cells express mRNA for the prohormone convertase 2 binding protein 7B2. Taken together these findings indicate that human dermal microvascular endothelial cells upon stimulation express both proopiomelanocortin and prohormone convertases required for the generation of alpha-melanocyte-stimulating hormone. As proopiomelanocortin peptides were found to regulate the production of human dermal microvascular endothelial cell cytokines and adhesion molecules and to have a variety of anti-inflammatory properties these peptides may significantly contribute to the modulation of skin inflammation. J Invest Dermatol 115:1021-1028 2000
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Affiliation(s)
- T E Scholzen
- Ludwig Boltzmann Institute for Cell Biology and Immunobiology of the Skin, Department of Dermatology, University of Münster, Germany
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28
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Slominski A, Wortsman J, Luger T, Paus R, Solomon S. Corticotropin releasing hormone and proopiomelanocortin involvement in the cutaneous response to stress. Physiol Rev 2000; 80:979-1020. [PMID: 10893429 DOI: 10.1152/physrev.2000.80.3.979] [Citation(s) in RCA: 559] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The skin is a known target organ for the proopiomelanocortin (POMC)-derived neuropeptides alpha-melanocyte stimulating hormone (alpha-MSH), beta-endorphin, and ACTH and also a source of these peptides. Skin expression levels of the POMC gene and POMC/corticotropin releasing hormone (CRH) peptides are not static but are determined by such factors as the physiological changes associated with hair cycle (highest in anagen phase), ultraviolet radiation (UVR) exposure, immune cytokine release, or the presence of cutaneous pathology. Among the cytokines, the proinflammatory interleukin-1 produces important upregulation of cutaneous levels of POMC mRNA, POMC peptides, and MSH receptors; UVR also stimulates expression of all the components of the CRH/POMC system including expression of the corresponding receptors. Molecular characterization of the cutaneous POMC gene shows mRNA forms similar to those found in the pituitary, which are expressed together with shorter variants. The receptors for POMC peptides expressed in the skin are functional and include MC1, MC5 and mu-opiate, although most predominant are those of the MC1 class recognizing MSH and ACTH. Receptors for CRH are also present in the skin. Because expression of, for example, the MC1 receptor is stimulated in a similar dose-dependent manner by UVR, cytokines, MSH peptides or melanin precursors, actions of the ligand peptides represent a stochastic (predictable) nonspecific response to environmental/endogenous stresses. The powerful effects of POMC peptides and probably CRH on the skin pigmentary, immune, and adnexal systems are consistent with stress-neutralizing activity addressed at maintaining skin integrity to restrict disruptions of internal homeostasis. Hence, cutaneous expression of the CRH/POMC system is highly organized, encoding mediators and receptors similar to the hypothalamic-pituitary-adrenal (HPA) axis. This CRH/POMC skin system appears to generate a function analogous to the HPA axis, that in the skin is expressed as a highly localized response which neutralizes noxious stimuli and attendant immune reactions.
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Affiliation(s)
- A Slominski
- Department of Pathology, Loyola University Medical Center, Maywood, Illinois, USA
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29
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Wintzen M, Zanello SB, Holick MF, Wiegant VM, Burbach JP, Vermeer BJ. Condition-dependent presence of beta-lipotropin-like peptide in human keratinocytes. Peptides 2000; 21:691-7. [PMID: 10876052 DOI: 10.1016/s0196-9781(00)00193-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This study aimed to characterize the beta-endorphin-immunoreactive material (betaE-IR) detectable in normal human keratinocytes (NHK). The effects of different culturing conditions and UV-irradiation on production of betaE-IR by NHK were assessed by radioimmunoassay and HPLC. All culture systems contained low levels of betaE-IR that was increased in conditioned media after UV-irradiation under certain conditions. NHK grown in nutrient-poor medium contained highest levels of betaE-IR that exhibited beta-lipotropin-like properties after HPLC analysis. The other culturing conditions displayed no authentic betaE-related peptides. Our results indicate that under certain culturing conditions NHK can produce POMC peptides like beta-lipotropin, which can be induced by UV-radiation.
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Affiliation(s)
- M Wintzen
- Department of Dermatology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands.
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