The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform

Markus Böhm - One of the best experts on this subject based on the ideXlab platform.

  • protection of glucotoxicity by a tripeptide derivative of α melanocyte stimulating Hormone in human epidermal keratinocytes
    British Journal of Dermatology, 2019
    Co-Authors: Paraskevi Gkogkolou, Michal Sarna, Tadeusz Sarna, Ralf Paus, T A Luger, Markus Böhm
    Abstract:

    Background Chronic skin ulcers are a major complication and a therapeutic challenge in patients with diabetes mellitus. Glucose-induced accumulation of reactive oxygen species (ROS) is considered to be an important pathogenetic factor in diabetes. Objectives To characterize the impact of high glucose (HG) on normal human keratinocytes (NHKs) and examine if Lys-d-Pro-Thr (KdPT), a tripeptide derived from α-Melanocyte-Stimulating-Hormone, has protective effects. Methods We investigated the key functions of NHKs under HG conditions with or without KdPT in vitro as well as ex vivo employing a skin organ culture model. Results HG impaired metabolic activity, cell proliferation, viability and migration of NHKs. As shown by atomic force microscopy HG altered the biophysical properties of NHKs, i.e. cell size and elasticity. Glucotoxicity in NHKs was paralleled by the induction of intracellular ROS and endoplasmic reticulum stress. KdPT attenuated HG-induced oxidative stress and antagonized the effects of glucose on cell viability, metabolic activity and migration. Importantly, KdPT also antagonized the suppressive effect of HG on epidermal migration in wounded human skin organ cultures. Conclusions Our findings highlight a novel effect of KdPT that could be exploited for the future therapy of diabetic skin ulcers.

  • α melanocyte stimulating Hormone suppresses bleomycin induced collagen synthesis and reduces tissue fibrosis in a mouse model of scleroderma melanocortin peptides as a novel treatment strategy for scleroderma
    Arthritis & Rheumatism, 2009
    Co-Authors: Agatha Kokot, Meinhard Schiller, Thomas A. Luger, Cord Sunderkotter, Anca Sindrilaru, Claus Kerkhoff, Beate Eckes, Karin Scharffetterkochanek, Markus Böhm
    Abstract:

    Objective Recently, we found that human dermal fibroblasts (HDFs) express melanocortin 1 receptors (MC-1R) that bind α-melanocyte–stimulating Hormone (α-MSH). In search of novel therapies for scleroderma (systemic sclerosis [SSc]), we used the bleomycin (BLM) model to investigate the effects of α-MSH on collagen synthesis and fibrosis. Methods Collagen expression in HDFs was determined by real-time reverse transcription–polymerase chain reaction (RT-PCR) and Western blot analyses. Signal transduction studies included pharmacologic blockade, immunofluorescence analysis, Western blotting, and reporter–promoter assays. Oxidative stress was measured by fluorescence-activated cell sorter analysis, and anti–oxidative enzyme levels were determined by real-time RT-PCR and Western blot analyses. The effect of α-MSH in the BLM mouse model of scleroderma was assessed by histologic, immunohistochemical, real-time RT-PCR, and protein analyses. Expression of MC-1R and pro-opiomelanocortin (POMC) in skin and HDF samples from patients with SSc was determined by RT-PCR and compared with that in samples from normal controls. Results Treatment with α-MSH (and related peptides) suppressed BLM-induced expression of type I and type III collagen in HDFs, and this effect was cAMP-dependent. Neither BLM nor α-MSH altered Smad signaling, but antioxidants inhibited BLM-induced collagen expression in vitro. In addition, α-MSH suppressed BLM-induced oxidative stress and enhanced the expression of superoxide dismutase 2 (SOD2) and heme oxygenase 1 (HO-1). In the BLM mouse model, α-MSH reduced skin fibrosis and collagen content and increased tissue levels of SOD2 and HO-1. In skin and HDFs from patients with SSc, both MC-1R and POMC messenger RNAs were detected, but there were no differences compared with healthy controls. Conclusion Alpha-melanocyte–stimulating Hormone and related peptides that exert their effects via MC-1R may provide a novel antifibrogenic therapeutic tool for the treatment of fibrotic diseases such as scleroderma.

  • α melanocyte stimulating Hormone protects from ultraviolet radiation induced apoptosis and dna damage
    Journal of Biological Chemistry, 2005
    Co-Authors: Markus Böhm, Thomas A. Luger, Thomas Scholzen, T Schwarz, E Healy, Ilka Wolff, Samantha J Robinson, Agatha Schwarz
    Abstract:

    Abstract Ultraviolet radiation is a well established epidemiologic risk factor for malignant melanoma. This observation has been linked to the relative resistance of normal melanocytes to ultraviolet B (UVB) radiation-induced apoptosis, which consequently leads to accumulation of UVB radiation-induced DNA lesions in melanocytes. Therefore, identification of physiologic factors regulating UVB radiation-induced apoptosis and DNA damage of melanocytes is of utmost biological importance. We show that the neuropeptide α-Melanocyte-Stimulating Hormone (α-MSH) blocks UVB radiation-induced apoptosis of normal human melanocytes in vitro. The anti-apoptotic activity of α-MSH is not mediated by filtering or by induction of melanin synthesis in melanocytes. α-MSH neither leads to changes in the cell cycle distribution nor induces alterations in the expression of the apoptosis-related proteins Bcl2, Bclx, Bax, p53, CD95 (Fas/APO-1), and CD95L (FasL). In contrast, α-MSH markedly reduces the formation of UVB radiation-induced DNA damage as demonstrated by reduced amounts of cyclobutane pyrimidine dimers, ultimately leading to reduced apoptosis. The reduction of UV radiation-induced DNA damage by α-MSH appears to be related to induction of nucleotide excision repair, because UV radiation-mediated apoptosis was not blocked by α-MSH in nucleotide excision repair-deficient fibroblasts. These data, for the first time, demonstrate regulation of UVB radiation-induced apoptosis of human melanocytes by a neuropeptide that is physiologically expressed within the epidermis. Apart from its ability to induce photoprotective melanin synthesis, α-MSH appears to exert the capacity to reduce UV radiation-induced DNA damage and, thus, may act as a potent protection factor against the harmful effects of UV radiation on the genomic stability of epidermal cells.

  • collagen metabolism is a novel target of the neuropeptide α melanocyte stimulating Hormone
    Journal of Biological Chemistry, 2004
    Co-Authors: Markus Böhm, Meinhard Schiller, Thomas Brzoska, Michael Raghunath, Cord Sunderkotter, Sonja Stander, Thomas Cauvet, Helgi B Schioth, T Schwarz, Thomas A. Luger
    Abstract:

    Collagen metabolism is a novel target of the neuropeptide alpha-Melanocyte-Stimulating Hormone

  • solar simulated ultraviolet radiation induced upregulation of the melanocortin 1 receptor proopiomelanocortin and α melanocyte stimulating Hormone in human epidermis in vivo
    Journal of Investigative Dermatology, 2004
    Co-Authors: Alain Rougier, Meinhard Schiller, Thomas Brzoska, Dieter Metze, Markus Böhm, Thomas Scholzen, Thomas A. Luger
    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 α-Melanocyte-Stimulating Hormone. Recently, in addition to its well-known pigmentation inducing activity, a strong anti-inflammatory as well as an immunomodulatory potential of α-Melanocyte-Stimulating Hormone has been recognized. The aim of this study was to determine, whether ultraviolet irradiation affects the expression of both α-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, α-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 Anthelios 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 α-Melanocyte-Stimulating Hormone may therefore play an important part in modulating ultraviolet-induced inflammation.

Thomas A. Luger - One of the best experts on this subject based on the ideXlab platform.

  • kdpt a tripeptide derivative of α melanocyte stimulating Hormone suppresses il 1β mediated cytokine expression and signaling in human sebocytes
    Journal of Immunology, 2010
    Co-Authors: Arianna Mastrofrancesco, Agatha Kokot, Alex N Eberle, Nicholas C J Gibbons, Karin U Schallreuter, Elwira Strozyk, Mauro Picardo, Christos C Zouboulis, Thomas A. Luger
    Abstract:

    Acne is the most common inflammatory skin disease in which IL-1 plays a central role. Although alpha-Melanocyte-Stimulating Hormone has immunomodulatory effects, its usefulness as an anti-inflammatory agent in acne is hampered owing to its lipid- and pigment-inducing effects via activation of melanocortin receptors (MC-Rs). We used the immortalized human sebocyte line SZ95 as an in vitro model to investigate the anti-inflammatory potential of KdPT, a tripeptide derivative of the C-terminal end of alpha-Melanocyte-Stimulating Hormone. KdPT potently suppressed IL-1beta-induced IL-6 and IL-8 expression. Mechanistically, KdPT decreased IL-1beta-mediated IkappaBalpha degradation, reduced nuclear accumulation of p65, and attenuated DNA binding of NF-kappaB. Moreover, KdPT reduced IL-1beta-mediated generation of intracellular reactive oxygen species, which contributed to IL-1beta-mediated cytokine induction. KdPT also reduced cell surface binding of fluorochrome-labeled IL-1beta in SZ95 sebocytes. Analysis of the crystal structure of the complex between IL-1beta/IL-1R type I (IL-1RI), followed by computer modeling of KdPT and subsequent modeling of the peptide receptor complex with the crystal structure of IL-1RI via manual docking, further predicted that the tripeptide, through several H-bonds and one hydrophobic bond, interacts with the IL-1RI. Importantly, KdPT did not bind to MC-1Rs, as demonstrated by blocking experiments with a peptide analog of Agouti signaling protein and by binding assays using MC-1R-expressing B16 melanoma cells. Accordingly, KdPT failed to induce melanogenesis. Our data demonstrate a promising anti-inflammatory potential of KdPT and point toward novel future directions in the treatment of acne-as well as of various other IL-1-mediated inflammatory diseases-with this small molecule.

  • α melanocyte stimulating Hormone suppresses bleomycin induced collagen synthesis and reduces tissue fibrosis in a mouse model of scleroderma melanocortin peptides as a novel treatment strategy for scleroderma
    Arthritis & Rheumatism, 2009
    Co-Authors: Agatha Kokot, Meinhard Schiller, Thomas A. Luger, Cord Sunderkotter, Anca Sindrilaru, Claus Kerkhoff, Beate Eckes, Karin Scharffetterkochanek, Markus Böhm
    Abstract:

    Objective Recently, we found that human dermal fibroblasts (HDFs) express melanocortin 1 receptors (MC-1R) that bind α-melanocyte–stimulating Hormone (α-MSH). In search of novel therapies for scleroderma (systemic sclerosis [SSc]), we used the bleomycin (BLM) model to investigate the effects of α-MSH on collagen synthesis and fibrosis. Methods Collagen expression in HDFs was determined by real-time reverse transcription–polymerase chain reaction (RT-PCR) and Western blot analyses. Signal transduction studies included pharmacologic blockade, immunofluorescence analysis, Western blotting, and reporter–promoter assays. Oxidative stress was measured by fluorescence-activated cell sorter analysis, and anti–oxidative enzyme levels were determined by real-time RT-PCR and Western blot analyses. The effect of α-MSH in the BLM mouse model of scleroderma was assessed by histologic, immunohistochemical, real-time RT-PCR, and protein analyses. Expression of MC-1R and pro-opiomelanocortin (POMC) in skin and HDF samples from patients with SSc was determined by RT-PCR and compared with that in samples from normal controls. Results Treatment with α-MSH (and related peptides) suppressed BLM-induced expression of type I and type III collagen in HDFs, and this effect was cAMP-dependent. Neither BLM nor α-MSH altered Smad signaling, but antioxidants inhibited BLM-induced collagen expression in vitro. In addition, α-MSH suppressed BLM-induced oxidative stress and enhanced the expression of superoxide dismutase 2 (SOD2) and heme oxygenase 1 (HO-1). In the BLM mouse model, α-MSH reduced skin fibrosis and collagen content and increased tissue levels of SOD2 and HO-1. In skin and HDFs from patients with SSc, both MC-1R and POMC messenger RNAs were detected, but there were no differences compared with healthy controls. Conclusion Alpha-melanocyte–stimulating Hormone and related peptides that exert their effects via MC-1R may provide a novel antifibrogenic therapeutic tool for the treatment of fibrotic diseases such as scleroderma.

  • α melanocyte stimulating Hormone protects from ultraviolet radiation induced apoptosis and dna damage
    Journal of Biological Chemistry, 2005
    Co-Authors: Markus Böhm, Thomas A. Luger, Thomas Scholzen, T Schwarz, E Healy, Ilka Wolff, Samantha J Robinson, Agatha Schwarz
    Abstract:

    Abstract Ultraviolet radiation is a well established epidemiologic risk factor for malignant melanoma. This observation has been linked to the relative resistance of normal melanocytes to ultraviolet B (UVB) radiation-induced apoptosis, which consequently leads to accumulation of UVB radiation-induced DNA lesions in melanocytes. Therefore, identification of physiologic factors regulating UVB radiation-induced apoptosis and DNA damage of melanocytes is of utmost biological importance. We show that the neuropeptide α-Melanocyte-Stimulating Hormone (α-MSH) blocks UVB radiation-induced apoptosis of normal human melanocytes in vitro. The anti-apoptotic activity of α-MSH is not mediated by filtering or by induction of melanin synthesis in melanocytes. α-MSH neither leads to changes in the cell cycle distribution nor induces alterations in the expression of the apoptosis-related proteins Bcl2, Bclx, Bax, p53, CD95 (Fas/APO-1), and CD95L (FasL). In contrast, α-MSH markedly reduces the formation of UVB radiation-induced DNA damage as demonstrated by reduced amounts of cyclobutane pyrimidine dimers, ultimately leading to reduced apoptosis. The reduction of UV radiation-induced DNA damage by α-MSH appears to be related to induction of nucleotide excision repair, because UV radiation-mediated apoptosis was not blocked by α-MSH in nucleotide excision repair-deficient fibroblasts. These data, for the first time, demonstrate regulation of UVB radiation-induced apoptosis of human melanocytes by a neuropeptide that is physiologically expressed within the epidermis. Apart from its ability to induce photoprotective melanin synthesis, α-MSH appears to exert the capacity to reduce UV radiation-induced DNA damage and, thus, may act as a potent protection factor against the harmful effects of UV radiation on the genomic stability of epidermal cells.

  • collagen metabolism is a novel target of the neuropeptide α melanocyte stimulating Hormone
    Journal of Biological Chemistry, 2004
    Co-Authors: Markus Böhm, Meinhard Schiller, Thomas Brzoska, Michael Raghunath, Cord Sunderkotter, Sonja Stander, Thomas Cauvet, Helgi B Schioth, T Schwarz, Thomas A. Luger
    Abstract:

    Collagen metabolism is a novel target of the neuropeptide alpha-Melanocyte-Stimulating Hormone

  • solar simulated ultraviolet radiation induced upregulation of the melanocortin 1 receptor proopiomelanocortin and α melanocyte stimulating Hormone in human epidermis in vivo
    Journal of Investigative Dermatology, 2004
    Co-Authors: Alain Rougier, Meinhard Schiller, Thomas Brzoska, Dieter Metze, Markus Böhm, Thomas Scholzen, Thomas A. Luger
    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 α-Melanocyte-Stimulating Hormone. Recently, in addition to its well-known pigmentation inducing activity, a strong anti-inflammatory as well as an immunomodulatory potential of α-Melanocyte-Stimulating Hormone has been recognized. The aim of this study was to determine, whether ultraviolet irradiation affects the expression of both α-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, α-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 Anthelios 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 α-Melanocyte-Stimulating Hormone may therefore play an important part in modulating ultraviolet-induced inflammation.

Rafael Armenta - One of the best experts on this subject based on the ideXlab platform.

  • melanocyte stimulating Hormone directly enhances uv induced dna repair in keratinocytes by a xeroderma pigmentosum group a dependent mechanism
    Cancer Research, 2010
    Co-Authors: Liang Dong, Ji Wen, Eric Pier, Xiao Zhang, Bo Zhang, Fangzheng Dong, Nick Ziegler, Margaret A Mysz, Rafael Armenta, Rutao Cui
    Abstract:

    Melanocyte-Stimulating Hormone (MSH) reduces UV-induced DNA damage through the induction of pigmentation. In this study, we provide evidence that MSH also enhances DNA repair in skin keratinocytes by modulating the function of DNA repair molecules. Intracutaneous injection of MSH prevented UV-induced DNA damage in human and mouse skin independent of its effects on melanogenesis. In keratinocytes, MSH bound to the melanocyte melanocortin receptor type 1 and activated adenylate cyclase activity, which in turn activated Xeroderma pigmentosum group A (XPA)-binding protein 1 and induced nuclear translocation of XPA, a critical factor controlling nucleotide excision repair signaling pathways. Together, our findings reveal a novel pigmentation-independent mechanism that underlies MSH-mediated DNA repair following UVB irradiation.

  • melanocyte stimulating Hormone directly enhances uv induced dna repair in keratinocytes by a xeroderma pigmentosum group a dependent mechanism
    Cancer Research, 2010
    Co-Authors: Liang Dong, Eric Pier, Xiao Zhang, Bo Zhang, Fangzheng Dong, Nick Ziegler, Margaret A Mysz, Rafael Armenta
    Abstract:

    Melanocyte-Stimulating Hormone (MSH) reduces UV-induced DNA damage through the induction of pigmentation. In this study, we provide evidence that MSH also enhances DNA repair in skin keratinocytes by modulating the function of DNA repair molecules. Intracutaneous injection of MSH prevented UV-induced DNA damage in human and mouse skin independent of its effects on melanogenesis. In keratinocytes, MSH bound to the melanocyte melanocortin receptor type 1 and activated adenylate cyclase activity, which in turn activated Xeroderma pigmentosum group A (XPA)–binding protein 1 and induced nuclear translocation of XPA, a critical factor controlling nucleotide excision repair signaling pathways. Together, our findings reveal a novel pigmentation-independent mechanism that underlies MSH–mediated DNA repair following UVB irradiation. Cancer Res; 70(9); 3547–56. ©2010 AACR.

Liang Dong - One of the best experts on this subject based on the ideXlab platform.

  • melanocyte stimulating Hormone directly enhances uv induced dna repair in keratinocytes by a xeroderma pigmentosum group a dependent mechanism
    Cancer Research, 2010
    Co-Authors: Liang Dong, Ji Wen, Eric Pier, Xiao Zhang, Bo Zhang, Fangzheng Dong, Nick Ziegler, Margaret A Mysz, Rafael Armenta, Rutao Cui
    Abstract:

    Melanocyte-Stimulating Hormone (MSH) reduces UV-induced DNA damage through the induction of pigmentation. In this study, we provide evidence that MSH also enhances DNA repair in skin keratinocytes by modulating the function of DNA repair molecules. Intracutaneous injection of MSH prevented UV-induced DNA damage in human and mouse skin independent of its effects on melanogenesis. In keratinocytes, MSH bound to the melanocyte melanocortin receptor type 1 and activated adenylate cyclase activity, which in turn activated Xeroderma pigmentosum group A (XPA)-binding protein 1 and induced nuclear translocation of XPA, a critical factor controlling nucleotide excision repair signaling pathways. Together, our findings reveal a novel pigmentation-independent mechanism that underlies MSH-mediated DNA repair following UVB irradiation.

  • melanocyte stimulating Hormone directly enhances uv induced dna repair in keratinocytes by a xeroderma pigmentosum group a dependent mechanism
    Cancer Research, 2010
    Co-Authors: Liang Dong, Eric Pier, Xiao Zhang, Bo Zhang, Fangzheng Dong, Nick Ziegler, Margaret A Mysz, Rafael Armenta
    Abstract:

    Melanocyte-Stimulating Hormone (MSH) reduces UV-induced DNA damage through the induction of pigmentation. In this study, we provide evidence that MSH also enhances DNA repair in skin keratinocytes by modulating the function of DNA repair molecules. Intracutaneous injection of MSH prevented UV-induced DNA damage in human and mouse skin independent of its effects on melanogenesis. In keratinocytes, MSH bound to the melanocyte melanocortin receptor type 1 and activated adenylate cyclase activity, which in turn activated Xeroderma pigmentosum group A (XPA)–binding protein 1 and induced nuclear translocation of XPA, a critical factor controlling nucleotide excision repair signaling pathways. Together, our findings reveal a novel pigmentation-independent mechanism that underlies MSH–mediated DNA repair following UVB irradiation. Cancer Res; 70(9); 3547–56. ©2010 AACR.

David E Fisher - One of the best experts on this subject based on the ideXlab platform.

  • a tissue restricted camp transcriptional response sox10 modulates α melanocyte stimulating Hormone triggered expression of microphthalmia associated transcription factor in melanocytes
    Journal of Biological Chemistry, 2003
    Co-Authors: Wade E Huber, Roydon E Price, Hans R Widlund, Ian J Davis, Michael Wegner, David E Fisher
    Abstract:

    α-Melanocyte-Stimulating Hormone (MSH) utilizes cAMP to trigger pigmentation of melanocytes via activation of melanocyte-restricted microphthalmia-associated transcription factor (M-MITF) expression. M-MITF is a melanocyte-restricted helix-loop-helix transcription factor capable of transactivating promoters for multiple genes whose products modulate pigmentation. Although M-MITF promoter activation by MSH is known to occur through a conserved cAMP-response element (CRE), it remains unclear how this CRE exhibits such exquisitely tissue-restricted responsiveness. Here we show that cAMP-mediated CRE-binding protein activation of the M-MITF promoter requires a second DNA element located ∼100 bp upstream, a site that is bound and activated by SOX10. Mutations in the SOX10 transcription factor, like MITF, results in a disorder known as Waardenburg Syndrome. The cAMP response of the M-MITF promoter was analyzed in melanoma and neuroblastoma cells (which are neural crest-derived but lack both M-MITF and SOX10 expression). M-MITF promoter responsiveness to cAMP was found to depend upon SOX10, and reciprocally, SOX10 transactivation was dependent upon the CRE. Ectopic SOX10 expression, in cooperation with cAMP signaling, activated the M-MITF promoter function and the expression of measurable endogenous M-MITF transcripts in neuroblastoma cells. SOX10dom, a mutant allele, failed to cooperate with cAMP in neuroblastoma cells and attenuated the cAMP responsiveness of the M-MITF promoter in melanoma cells. These observations demonstrate a means whereby the ubiquitous cAMP signaling machinery is harnessed to produce a highly tissue-restricted transcriptional response by cooperating with architectural factors, in this case SOX10.

  • a tissue restricted camp transcriptional response sox10 modulates α melanocyte stimulating Hormone triggered expression of microphthalmia associated transcription factor in melanocytes
    Journal of Biological Chemistry, 2003
    Co-Authors: Wade E Huber, Roydon E Price, Hans R Widlund, Ian J Davis, Michael Wegner, David E Fisher
    Abstract:

    alpha-Melanocyte-Stimulating Hormone (MSH) utilizes cAMP to trigger pigmentation of melanocytes via activation of melanocyte-restricted microphthalmia-associated transcription factor (M-MITF) expression. M-MITF is a melanocyte-restricted helix-loop-helix transcription factor capable of transactivating promoters for multiple genes whose products modulate pigmentation. Although M-MITF promoter activation by MSH is known to occur through a conserved cAMP-response element (CRE), it remains unclear how this CRE exhibits such exquisitely tissue-restricted responsiveness. Here we show that cAMP-mediated CRE-binding protein activation of the M-MITF promoter requires a second DNA element located approximately 100 bp upstream, a site that is bound and activated by SOX10. Mutations in the SOX10 transcription factor, like MITF, results in a disorder known as Waardenburg Syndrome. The cAMP response of the M-MITF promoter was analyzed in melanoma and neuroblastoma cells (which are neural crest-derived but lack both M-MITF and SOX10 expression). M-MITF promoter responsiveness to cAMP was found to depend upon SOX10, and reciprocally, SOX10 transactivation was dependent upon the CRE. Ectopic SOX10 expression, in cooperation with cAMP signaling, activated the M-MITF promoter function and the expression of measurable endogenous M-MITF transcripts in neuroblastoma cells. SOX10dom, a mutant allele, failed to cooperate with cAMP in neuroblastoma cells and attenuated the cAMP responsiveness of the M-MITF promoter in melanoma cells. These observations demonstrate a means whereby the ubiquitous cAMP signaling machinery is harnessed to produce a highly tissue-restricted transcriptional response by cooperating with architectural factors, in this case SOX10.

  • α melanocyte stimulating Hormone signaling regulates expression of microphthalmia a gene deficient in waardenburg syndrome
    Journal of Biological Chemistry, 1998
    Co-Authors: Roydon E Price, Martin A Horstmann, Audrey G Wells, Kathy N Weilbaecher, Clifford M Takemoto, Marc W Landis, David E Fisher
    Abstract:

    Abstract The pituitary peptide α-Melanocyte-Stimulating Hormone (α-MSH) stimulates melanocytes to up-regulate cAMP, but the downstream targets of cAMP are not well understood mechanistically. One consequence of α-MSH stimulation is increased melanization attributable to induction of pigmentation enzymes, including tyrosinase, which catalyzes a rate-limiting step in melanin synthesis. The tyrosinase promoter is a principle target of the melanocyte transcription factor Microphthalmia (Mi), a factor for which deficiency in humans causes Waardenburg syndrome II. We show here that both α-MSH and forskolin, a drug that increases cAMP, stimulate a rapid increase in Mi mRNA and protein levels in both melanoma cell lines and primary melanocytes. This up-regulation requires a cAMP-responsive element within the Mi promoter, and the pathway leading to Mi stimulation is subject to tight homeostatic regulation. Although cAMP signaling is ubiquitous, the Mi promoter was seen to be cAMP-responsive in melanocytes but not in nonmelanocytes. Moreover, dominant negative interference with Mi impeded successful α-MSH stimulation of tyrosinase. The regulation of Mi expression via α-MSH thus provides a direct mechanistic link to pigmentation. In addition, because the human melanocyte and deafness condition Waardenburg syndrome is sometimes caused by haploinsufficiency of Mi, its modulation by α-MSH suggests therapeutic strategies targeted at up-regulating the remaining wild type Mi allele.