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Metabolic engineering of Corynebacterium glutamicum for de novo production of 3-hydroxycadaverine. CURRENT RESEARCH IN BIOTECHNOLOGY 2022. [DOI: 10.1016/j.crbiot.2021.12.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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2
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Ma J, Li S, Zhu L, Guo S, Yi X, Cui T, He Y, Chang Y, Liu B, Li C, Jian Z. Baicalein protects human vitiligo melanocytes from oxidative stress through activation of NF-E2-related factor2 (Nrf2) signaling pathway. Free Radic Biol Med 2018; 129:492-503. [PMID: 30342186 DOI: 10.1016/j.freeradbiomed.2018.10.421] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 08/26/2018] [Accepted: 10/09/2018] [Indexed: 12/30/2022]
Abstract
Vitiligo is a complex disorder characterized by patchy loss of skin pigmentation due to abnormal melanocyte function. Overwhelming evidences have suggested that oxidative stress plays a major role in the loss of melanocytes thereby mediating the onset and progression of vitiligo. The nuclear factor erythroid 2-like factor 2 (Nrf2) is a master regulator of cellular redox homeostasis and the activation of Nrf2 signaling pathway is impaired in the vitiligo melanocytes. Baicalein, as flavonoid extracted from the Scutellaria baicalensis, has been proved to possess the ability to activate Nrf2 signaling pathway in other cell types and mouse model. Our previous data found that baicalein exerts a cytoprotective role in H2O2-induced apoptosis in human melanocytes cell line (PIG1). Based on these founding, we hypothesized that baicalein activates Nrf2 signaling pathway, alleviates H2O2-induced mitochondrial dysfunction and cellular damage, thereby protecting human vitiligo melanocytes from oxidative stress. In the present study, we found that baicalein effectively inhibited H2O2-induced cytotoxicity and apoptosis in human vitiligo melanocytes (PIG3V). Further results demonstrated that baicalein promoted Nrf2 nucleus translocation as well as up-regulated the expression of Nrf2 and its target gene, heme oxygenase-1 (HO-1). Moreover, the protective effects of baicalein against H2O2-induced cellular damage and apoptosis as well as mitochondrial dysfunction were abolished by Nrf2 knockdown. Additionally, we observed that Nrf2 knockdown suppressed proliferation and increased the sensitivity of PIG3V cells to H2O2 treatment. Finally, we explored the mechanism of baicalein associated with Nrf2 activation and found that the phosphorylation of Nrf2 as well as ERK1/2and PI3K/AKT signaling were not involved in the baicalein-induced activation of Nrf2. Taken together, these data clearly suggest that baicalein enhances cellular antioxidant defense capacity of human vitiligo melanocytes through the activation of the Nrf2 signaling pathway, providing beneficial evidence for the application of baicalein in the vitiligo treatment.
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Affiliation(s)
- Jingjing Ma
- Department of Dermatology, Xijing Hospital, Fourth Military Medical University, No. 127 Changlexi Road, Xi'an 710032, Shaanxi, China
| | - Shuli Li
- Department of Dermatology, Xijing Hospital, Fourth Military Medical University, No. 127 Changlexi Road, Xi'an 710032, Shaanxi, China
| | - Longfei Zhu
- Department of Dermatology, Xijing Hospital, Fourth Military Medical University, No. 127 Changlexi Road, Xi'an 710032, Shaanxi, China
| | - Sen Guo
- Department of Dermatology, Xijing Hospital, Fourth Military Medical University, No. 127 Changlexi Road, Xi'an 710032, Shaanxi, China
| | - Xiuli Yi
- Department of Dermatology, Xijing Hospital, Fourth Military Medical University, No. 127 Changlexi Road, Xi'an 710032, Shaanxi, China
| | - Tingting Cui
- Department of Dermatology, Xijing Hospital, Fourth Military Medical University, No. 127 Changlexi Road, Xi'an 710032, Shaanxi, China
| | - Yuanmin He
- Department of Dermatology, Xijing Hospital, Fourth Military Medical University, No. 127 Changlexi Road, Xi'an 710032, Shaanxi, China
| | - Yuqian Chang
- Department of Dermatology, Xijing Hospital, Fourth Military Medical University, No. 127 Changlexi Road, Xi'an 710032, Shaanxi, China
| | - Bangmin Liu
- Department of Dermatology, Xijing Hospital, Fourth Military Medical University, No. 127 Changlexi Road, Xi'an 710032, Shaanxi, China.
| | - Chunying Li
- Department of Dermatology, Xijing Hospital, Fourth Military Medical University, No. 127 Changlexi Road, Xi'an 710032, Shaanxi, China.
| | - Zhe Jian
- Department of Dermatology, Xijing Hospital, Fourth Military Medical University, No. 127 Changlexi Road, Xi'an 710032, Shaanxi, China.
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3
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Śniegocka M, Podgórska E, Płonka PM, Elas M, Romanowska-Dixon B, Szczygieł M, Żmijewski MA, Cichorek M, Markiewicz A, Brożyna AA, Słominski AT, Urbańska K. Transplantable Melanomas in Hamsters and Gerbils as Models for Human Melanoma. Sensitization in Melanoma Radiotherapy-From Animal Models to Clinical Trials. Int J Mol Sci 2018; 19:E1048. [PMID: 29614755 PMCID: PMC5979283 DOI: 10.3390/ijms19041048] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 03/27/2018] [Accepted: 03/28/2018] [Indexed: 12/18/2022] Open
Abstract
The focus of the present review is to investigate the role of melanin in the radioprotection of melanoma and attempts to sensitize tumors to radiation by inhibiting melanogenesis. Early studies showed radical scavenging, oxygen consumption and adsorption as mechanisms of melanin radioprotection. Experimental models of melanoma in hamsters and in gerbils are described as well as their use in biochemical and radiobiological studies, including a spontaneously metastasizing ocular model. Some results from in vitro studies on the inhibition of melanogenesis are presented as well as radio-chelation therapy in experimental and clinical settings. In contrast to cutaneous melanoma, uveal melanoma is very successfully treated with radiation, both using photon and proton beams. We point out that the presence or lack of melanin pigmentation should be considered, when choosing therapeutic options, and that both the experimental and clinical data suggest that melanin could be a target for radiosensitizing melanoma cells to increase efficacy of radiotherapy against melanoma.
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Affiliation(s)
- Martyna Śniegocka
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Kraków, 31-007 Kraków, Poland.
| | - Ewa Podgórska
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Kraków, 31-007 Kraków, Poland.
| | - Przemysław M Płonka
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Kraków, 31-007 Kraków, Poland.
| | - Martyna Elas
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Kraków, 31-007 Kraków, Poland.
| | - Bożena Romanowska-Dixon
- Department of Ophthalmology and Ocular Oncology, Medical College of Jagiellonian University in Kraków, 31-007 Kraków, Poland.
| | - Małgorzata Szczygieł
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Kraków, 31-007 Kraków, Poland.
| | - Michał A Żmijewski
- Department of Histology, Medical University of Gdansk, 80-210 Gdańsk, Poland.
| | - Mirosława Cichorek
- Department of Embryology, Medical University of Gdansk, 80-210 Gdańsk, Poland.
| | - Anna Markiewicz
- Department of Ophthalmology and Ocular Oncology, Medical College of Jagiellonian University in Kraków, 31-007 Kraków, Poland.
| | - Anna A Brożyna
- Department of Tumor Pathology and Pathomorphology, Faculty of Health Sciences, Nicolaus Copernicus University Collegium Medicum in Bydgoszcz, Oncology Centre-Prof. Franciszek Łukaszczyk Memorial Hospital, 85-796 Bydgoszcz, Poland.
- Department of Dermatology, Comprehensive Cancer Center Cancer Chemoprevention Program, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
| | - Andrzej T Słominski
- Department of Dermatology, Comprehensive Cancer Center Cancer Chemoprevention Program, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
- VA Medical Center, Birmingham, AL 35294, USA.
| | - Krystyna Urbańska
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Kraków, 31-007 Kraków, Poland.
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Chen P, Wang J, Li H, Li Y, Chen P, Li T, Chen X, Xiao J, Zhang L. Role of GTP-CHI links PAH and TH in melanin synthesis in silkworm, Bombyx mori. Gene 2015; 567:138-45. [PMID: 25958343 DOI: 10.1016/j.gene.2015.03.043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 03/19/2015] [Accepted: 03/20/2015] [Indexed: 10/23/2022]
Abstract
In insects, pigment patterns are formed by melanin, ommochromes, and pteridines. Here, the effects of pteridine synthesis on melanin formation were studied using 4th instar larvae of a wild-type silkworm strain, dazao (Bombyx mori), with normal color and markings. Results from injected larvae and in vitro integument culture indicated that decreased activity of guanosine triphosphate cyclohydrolase I (GTP-CH I, a rate-limiting enzyme for pteridine synthesis), lowers BH4 (6R-l-erythro-5,6,7,8-tetrahydrobiopterin, a production correlated with GTP-CH I activity) levels and eliminates markings and coloration. The conversion of phenylalanine and tyrosine to melanin was prevented when GTP-CH I was inhibited. When BH4 was added, phenylalanine was converted to tyrosine, and the tyrosine concentration increased. Tyrosine was then converted to melanin to create normal markings and coloration. Decreasing GTP-CH I activity did not affect L-DOPA (3,4-l-dihydroxyphenylalanine). GTP-CH I affected melanin synthesis by generating the BH4 used in two key reaction steps: (1) conversion of phenylalanine to tyrosine by PAH (phenylalanine hydroxylase) and (2) conversion of tyrosine to L-DOPA by TH (tyrosine hydroxylase). Expression profiles of BmGTPCH Ia, BmGTPCH Ib, BmTH, and BmPAH in the integument were consistent with the current findings.
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Affiliation(s)
- Ping Chen
- College of Biotechnology, Southwest University, Chongqing 400716, China.
| | - Jiying Wang
- College of Biotechnology, Southwest University, Chongqing 400716, China
| | - Haiyin Li
- College of Biotechnology, Southwest University, Chongqing 400716, China
| | - Yan Li
- College of Biotechnology, Southwest University, Chongqing 400716, China
| | - Peng Chen
- College of Biotechnology, Southwest University, Chongqing 400716, China
| | - Tian Li
- College of Biotechnology, Southwest University, Chongqing 400716, China
| | - Xi Chen
- College of Biotechnology, Southwest University, Chongqing 400716, China
| | - Junjie Xiao
- College of Biotechnology, Southwest University, Chongqing 400716, China
| | - Liang Zhang
- College of Biotechnology, Southwest University, Chongqing 400716, China
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Katoulis A, Alevizou A, Soura E, Mantas N, Bozi E, Gregoriou S, Makris M, Rigopoulos D. A double-blind vehicle-controlled study of a preparation containing undecylenoyl phenylalanine 2% in the treatment of melasma in females. J Cosmet Dermatol 2014; 13:86-90. [DOI: 10.1111/jocd.12089] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/16/2014] [Indexed: 11/28/2022]
Affiliation(s)
- Alexander Katoulis
- Second Department of Dermatology and Venereology; National and Kapodistrian University of Athens Medical School; “Attikon” General University Hospital; Athens Greece
| | - Antigoni Alevizou
- Second Department of Dermatology and Venereology; National and Kapodistrian University of Athens Medical School; “Attikon” General University Hospital; Athens Greece
| | - Efthymia Soura
- Second Department of Dermatology and Venereology; National and Kapodistrian University of Athens Medical School; “Attikon” General University Hospital; Athens Greece
| | - Nikolaos Mantas
- Second Department of Dermatology and Venereology; National and Kapodistrian University of Athens Medical School; “Attikon” General University Hospital; Athens Greece
| | - Evangelia Bozi
- Second Department of Dermatology and Venereology; National and Kapodistrian University of Athens Medical School; “Attikon” General University Hospital; Athens Greece
| | - Stamatis Gregoriou
- Second Department of Dermatology and Venereology; National and Kapodistrian University of Athens Medical School; “Attikon” General University Hospital; Athens Greece
| | - Michalis Makris
- Second Department of Dermatology and Venereology; National and Kapodistrian University of Athens Medical School; “Attikon” General University Hospital; Athens Greece
| | - Dimitris Rigopoulos
- Second Department of Dermatology and Venereology; National and Kapodistrian University of Athens Medical School; “Attikon” General University Hospital; Athens Greece
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Schallreuter KU, Salem MAEL, Holtz S, Panske A. Basic evidence for epidermal H2O2/ONOO(-)-mediated oxidation/nitration in segmental vitiligo is supported by repigmentation of skin and eyelashes after reduction of epidermal H2O2 with topical NB-UVB-activated pseudocatalase PC-KUS. FASEB J 2013; 27:3113-22. [PMID: 23629861 DOI: 10.1096/fj.12-226779] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Nonsegmental vitiligo (NSV) is characterized by loss of inherited skin color. The cause of the disease is still unknown despite accumulating in vivo and in vitro evidence of massive epidermal oxidative stress via H2O2 and peroxynitrite (ONOO(-)) in affected individuals. The most favored hypothesis is based on autoimmune mechanisms. Strictly segmental vitiligo (SSV) with dermatomal distribution is a rare entity, often associated with stable outcome. Recently, it was documented that this form can be associated with NSV (mixed vitiligo). We here asked the question whether ROS and possibly ONOO(-) could be players in the pathogenesis of SSV. Our in situ results demonstrate for the first time epidermal biopterin accumulation together with significantly decreased epidermal catalase, thioredoxin/thioreoxin reductase, and MSRA/MSRB expression. Moreover, we show epidermal ONOO(-) accumulation. In vivo FT-Raman spectroscopy reveals the presence of H2O2, methionine sulfoxide, and tryptophan metabolites; i.e., N-formylkynurenine and kynurenine, implying Fenton chemistry in the cascade (n=10). Validation of the basic data stems from successful repigmentation of skin and eyelashes in affected individuals, regardless of SSV or segmental vitiligo in association with NSV after reduction of epidermal H2O2 (n=5). Taken together, our contribution strongly supports H2O2/ONOO-mediated stress in the pathogenesis of SSV. Our findings offer new treatment intervention for lost skin and hair color.
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Affiliation(s)
- Karin U Schallreuter
- Institute for Pigmentary Disorders, E. M. Arndt University, Greifswald, Germany.
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7
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Liu B, Jian Z, Li Q, Li K, Wang Z, Liu L, Tang L, Yi X, Wang H, Li C, Gao T. Baicalein protects human melanocytes from H₂O₂-induced apoptosis via inhibiting mitochondria-dependent caspase activation and the p38 MAPK pathway. Free Radic Biol Med 2012; 53:183-93. [PMID: 22569306 DOI: 10.1016/j.freeradbiomed.2012.04.015] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Revised: 04/11/2012] [Accepted: 04/12/2012] [Indexed: 11/30/2022]
Abstract
The removal of H(2)O(2) by antioxidants has been proven to be beneficial to patients with vitiligo. Baicalein (5,6,7-trihydroxyflavone; BE) has antioxidant activity and has been used in vitiligo therapy in Chinese traditional medicine. In this study, we investigated the potential protective effect and mechanisms of BE against H(2)O(2)-induced apoptosis in human melanocytes. Melanocytes from the PIG1 cell line were pretreated with different concentrations of BE for 1 h, followed by exposure to 1.0 mM H(2)O(2) for 24 h. Cell apoptosis, reactive oxygen species levels, and mitochondrial membrane potentials were evaluated by flow cytometry, and cell viability was determined by an MTT assay. The expressions of Bax, Bcl-2, caspase-3, total and phosphorylated ERKs, and p38 MAPK were assayed by Western blot to investigate the possible molecular mechanisms. Our results showed that BE significantly inhibited H(2)O(2)-induced apoptosis, intracellular reactive oxygen species generation, and changes in the mitochondrial membrane potential. It also reduced the Bax/Bcl-2 ratio, the release of cytochrome c, the activation of caspase-3, and the phosphorylation of p38 MAPK in a concentration-dependent manner. The results demonstrate for the first time that BE exerts a cytoprotective role in H(2)O(2)-induced apoptosis by inhibiting the mitochondria-dependent caspase activation and p38 MAPK pathway.
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Affiliation(s)
- Bangmin Liu
- Department of Dermatology, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi, China 710032
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8
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Dell'Anna ML, Cario-André M, Bellei B, Taieb A, Picardo M. In vitro research on vitiligo: strategies, principles, methodological options and common pitfalls. Exp Dermatol 2012; 21:490-6. [DOI: 10.1111/j.1600-0625.2012.01506.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
| | - Muriel Cario-André
- Inserm U 876 and National Reference Centre for Rare Skin Diseases; Bordeaux University Hospitals; Bordeaux; France
| | | | - Alain Taieb
- Inserm U 876 and National Reference Centre for Rare Skin Diseases; Bordeaux University Hospitals; Bordeaux; France
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9
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Schallreuter KU, Salem MAEL, Gibbons NCJ, Maitland DJ, Marsch E, Elwary SMA, Healey AR. Blunted epidermal L-tryptophan metabolism in vitiligo affects immune response and ROS scavenging by Fenton chemistry, part 2: Epidermal H2O2/ONOO(-)-mediated stress in vitiligo hampers indoleamine 2,3-dioxygenase and aryl hydrocarbon receptor-mediated immune response signaling. FASEB J 2012; 26:2471-85. [PMID: 22415306 DOI: 10.1096/fj.11-201897] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Vitiligo is characterized by a mostly progressive loss of the inherited skin color. The cause of the disease is still unknown, despite accumulating in vivo and in vitro evidence of massive oxidative stress via hydrogen peroxide (H(2)O(2)) and peroxynitrite (ONOO(-)) in the skin of affected individuals. The most favored hypothesis is based on autoimmune mechanisms. Since depletion of the essential amino acid L-tryptophan (Trp) severely affects various immune responses, we here looked at Trp metabolism and signaling in these patients. Our in vivo and in vitro data revealed total absence of epidermal Trp hydroxylase activities and the presence of H(2)O(2)/ONOO(-) deactivated indoleamine 2,3-dioxygenase. Aryl hydrocarbon receptor signaling is severely impaired despite the ligand (Trp dimer) being formed, as shown by mass spectrometry. Loss of this signal is supported by the absence of downstream signals (COX-2 and CYP1A1) as well as regulatory T-lymphocytes and by computer modeling. In vivo Fourier transform Raman spectroscopy confirmed the presence of Trp metabolites together with H(2)O(2) supporting deprivation of the epidermal Trp pool by Fenton chemistry. Taken together, our data support a long-expressed role for in loco redox balance and a distinct immune response. These insights could open novel treatment strategies for this disease.
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Affiliation(s)
- Karin U Schallreuter
- Institute for Pigmentary Disorders, E. M. Arndt University, Greifswald, Germany.
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Schallreuter KU, Salem MAEL, Gibbons NCJ, Martinez A, Slominski R, Lüdemann J, Rokos H. Blunted epidermal L-tryptophan metabolism in vitiligo affects immune response and ROS scavenging by Fenton chemistry, part 1: Epidermal H2O2/ONOO(-)-mediated stress abrogates tryptophan hydroxylase and dopa decarboxylase activities, leading to low serotonin and melatonin levels. FASEB J 2012; 26:2457-70. [PMID: 22415302 DOI: 10.1096/fj.11-197137] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Vitiligo is characterized by a progressive loss of inherited skin color. The cause of the disease is still unknown. To date, there is accumulating in vivo and in vitro evidence for massive oxidative stress via hydrogen peroxide (H(2)O(2)) and peroxynitrite (ONOO(-)) in the skin of affected individuals. Autoimmune etiology is the favored theory. Since depletion of the essential amino acid L-tryptophan (Trp) affects immune response mechanisms, we here looked at epidermal Trp metabolism via tryptophan hydroxylase (TPH) with its downstream cascade, including serotonin and melatonin. Our in situ immunofluorescence and Western blot data reveal significantly lower TPH1 expression in patients with vitiligo. Expression is also low in melanocytes and keratinocytes under in vitro conditions. Although in vivo Fourier transform-Raman spectroscopy proves the presence of 5-hydroxytryptophan, epidermal TPH activity is completely absent. Regulation of TPH via microphthalmia-associated transcription factor and L-type calcium channels is severely affected. Moreover, dopa decarboxylase (DDC) expression is significantly lower, in association with decreased serotonin and melatonin levels. Computer simulation supports H(2)O(2)/ONOO(-)-mediated oxidation/nitration of TPH1 and DDC, affecting, in turn, enzyme functionality. Taken together, our data point to depletion of epidermal Trp by Fenton chemistry and exclude melatonin as a relevant contributor to epidermal redox balance and immune response in vitiligo.
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Affiliation(s)
- Karin U Schallreuter
- Institute for Pigmentary Disorders, E. M. Arndt University, Greifswald, Germany.
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11
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Structure and stability of the molybdenum cofactor intermediate cyclic pyranopterin monophosphate. J Biol Inorg Chem 2011; 17:113-22. [DOI: 10.1007/s00775-011-0835-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2011] [Accepted: 08/15/2011] [Indexed: 11/25/2022]
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12
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Rakovich T, Boland C, Bernstein I, Chikwana VM, Iwata-Reuyl D, Kelly VP. Queuosine deficiency in eukaryotes compromises tyrosine production through increased tetrahydrobiopterin oxidation. J Biol Chem 2011; 286:19354-63. [PMID: 21487017 DOI: 10.1074/jbc.m111.219576] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Queuosine is a modified pyrrolopyrimidine nucleoside found in the anticodon loop of transfer RNA acceptors for the amino acids tyrosine, asparagine, aspartic acid, and histidine. Because it is exclusively synthesized by bacteria, higher eukaryotes must salvage queuosine or its nucleobase queuine from food and the gut microflora. Previously, animals made deficient in queuine died within 18 days of withdrawing tyrosine, a nonessential amino acid, from the diet (Marks, T., and Farkas, W. R. (1997) Biochem. Biophys. Res. Commun. 230, 233-237). Here, we show that human HepG2 cells deficient in queuine and mice made deficient in queuosine-modified transfer RNA, by disruption of the tRNA guanine transglycosylase enzyme, are compromised in their ability to produce tyrosine from phenylalanine. This has similarities to the disease phenylketonuria, which arises from mutation in the enzyme phenylalanine hydroxylase or from a decrease in the supply of its cofactor tetrahydrobiopterin (BH4). Immunoblot and kinetic analysis of liver from tRNA guanine transglycosylase-deficient animals indicates normal expression and activity of phenylalanine hydroxylase. By contrast, BH4 levels are significantly decreased in the plasma, and both plasma and urine show a clear elevation in dihydrobiopterin, an oxidation product of BH4, despite normal activity of the salvage enzyme dihydrofolate reductase. Our data suggest that queuosine modification limits BH4 oxidation in vivo and thereby potentially impacts on numerous physiological processes in eukaryotes.
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Affiliation(s)
- Tatsiana Rakovich
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland
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13
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Boonyapiwat B, Mitchell SC, Steventon GB. Recombinant heteromeric phenylalanine monooxygenase and the oxygenation of carbon and sulfur substrates. J Pharm Pharmacol 2011; 63:558-64. [DOI: 10.1111/j.2042-7158.2010.01242.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Abstract
Objectives
The aim of this investigation was to provide in-vitro enzyme kinetic data to support the hypothesis that the in-vivo heterozygous dominant phenotype for phenylalanine monooxygenase (hPAH) was responsible for the S-oxidation polymorphism in the metabolism of S-carboxymethyl-l-cysteine reported in humans. Using a dual-vector expression strategy for the co-production of wild-type and mutant human hPAH subunits we report for the first time the kinetic parameters (Km, Vmax, CLE) for the C-oxidation of l-phenylalanine and the S-oxidation of S-carboxymethyl-l-cysteine in homomeric wild-type, heteromeric mutant and homomeric mutant hPAH proteins in vitro.
Methods
A PROTM dual-vector bacterial expression system was used to produce the required hPAH proteins. Enzyme activity was determined by HPLC with fluorescence detection.
Key findings
The heteromeric hPAH proteins (I65T, R68S, R158Q, I174T, R261Q, V338M, R408W and Y414C) all showed significantly decreased Vmax and CLE values when compared to the homomeric wild-type hPAH enzyme. For both substrates, all calculated Km values were significantly higher than homomeric wild-type hPAH enzyme, with the exception of I65T, R68S and Y414C heteromeric hPAH proteins employing l-phenylalanine as substrate.
Conclusions
The net outcome for the heteromeric mutant hPAH proteins was a decrease significantly more dramatic for S-carboxymethyl-l-cysteine S-oxidation (1.0–18.8% of homomeric wild-type hPAH activity) when compared to l-phenylalanine C-oxidation (25.9–52.9% of homomeric wild-type hPAH activity) as a substrate. Heteromeric hPAH enzyme may be related to the variation in S-carboxymethyl-l-cysteine S-oxidation capacity observed in humans.
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Affiliation(s)
- Boontarika Boonyapiwat
- Bureau of Drug and Narcotic, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, Thailand
| | - Stephen C Mitchell
- Imperial College London, Biomolecular Medicine, Division of Surgery, Faculty of Medicine, South Kensington, London, UK
| | - Glyn B Steventon
- University of Surrey, Clinical Medicine Division, Postgraduate Medical School, Daphne Jackson Road, Manor Park, Guildford, Surrey, UK
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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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Boonyapiwat B, Panaretou B, Forbes B, Mitchell SC, Steventon GB. Human phenylalanine monooxygenase and thioether metabolism. J Pharm Pharmacol 2010. [DOI: 10.1211/jpp.61.01.0009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Abstract
Objectives
The substrate specificity of wild-type human phenylalanine monooxygenase (wt-hPAH) has been investigated with respect to the mucoactive drug, S-carboxymethyl-L-cysteine and its thioether metabolites. The ability of wt-hPAH to metabolise other S-substituted cysteines was also examined.
Methods
Direct assays of PAH activity were by HPLC with fluorescence detection; indirect assays involved following disappearance of the cofactor by UV spectroscopy.
Key findings
wt-hPAH catalysed the S-oxygenation of S-carboxymethyl-L-cysteine, its decarboxylated metabolite, S-methyl-L-cysteine, and both their corresponding N-acetylated forms. However, thiodiglycolic acid was not a substrate. The enzyme profiles for both phenylalanine and S-carboxymethyl-L-cysteine showed allosteric kinetics at low substrate concentrations, with Hill constants of 2.0 and 1.9, respectively, for the substrate-activated wt-hPAH. At higher concentrations, both compounds followed Michaelis–Menten kinetics, with non-competitive substrate inhibition profiles. The thioether compounds, S-ethyl-L-cysteine, S-propyl-L-cysteine and S-butyl-L-cysteine were all found to be substrates for phenylalanine monooxygenase.
Conclusions
Phenylalanine monooxygenase may play a wider role outside intermediary metabolism in the biotransformation of dietary-derived substituted cysteines and other exogenous thioether compounds.
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Affiliation(s)
- Boontarika Boonyapiwat
- Bureau of Drug and Narcotic, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, Thailand
| | - Barry Panaretou
- King's College London, Pharmaceutical Science Division, School of Biomedical and Health Sciences, London, UK
| | - Ben Forbes
- King's College London, Pharmaceutical Science Division, School of Biomedical and Health Sciences, London, UK
| | - Stephen C Mitchell
- Imperial College London, Biomolecular Science, SORA Division, Faculty of Medicine, London, UK
| | - Glyn B Steventon
- King's College London, Pharmaceutical Science Division, School of Biomedical and Health Sciences, London, UK
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Katoulis AC, Alevizou A, Bozi E, Makris M, Zafeiraki A, Mantas N, Kousta F, Mistidou M, Kanelleas A, Stavrianeas NG. A randomized, double-blind, vehicle-controlled study of a preparation containing undecylenoyl phenylalanine 2% in the treatment of solar lentigines. Clin Exp Dermatol 2009; 35:473-6. [PMID: 19874316 DOI: 10.1111/j.1365-2230.2009.03605.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Solar lentigines are common, benign, cosmetically disfiguring lesions. Available physical treatments are effective, but they are costly and carry risks of side-effects. OBJECTIVE To evaluate the efficacy and safety of a preparation containing undecylenoyl phenylalanine 2% in the topical treatment of solar lentigines. METHODS In total, 36 patients with solar lentigines of the hands were randomly assigned to apply the active preparation on one side and the vehicle alone on the other side, twice daily for 12 weeks. Patients were evaluated monthly for efficacy and safety. RESULTS In all, 30 patients (28 women and 2 men; age range 47-75 years) completed the study. The duration of lesions ranged from 8 months to > 10 years. All patients responded partially on the side of the active treatment. Of the partial responders, 19 (63.3%) had moderate improvement and 11 (36.6%) had marked improvement. Improvement was evident from the first follow-up visit. On the side of the vehicle, 26 remained stable (86.6%) and 4 (13.3%) had partial improvement. There was a significant difference (P < 0.01) in efficacy of the active preparation vs. the vehicle. Using patient assessment ratings, 80% were 'much more satisfied/more satisfied' with the result. The reported side-effects were minor and included erythema and itching or burning on the side of active treatment. CONCLUSIONS Undecylenoyl phenylalanine 2% is a novel depigmenting agent, which possibly acts as an alpha-melanocyte-stimulating hormone antagonist, thus inhibiting melaninogenesis. It achieved a significant lightening of the lesions with minimal side-effects. Most patients were satisfied with the improvement. Undecylenoyl phenylalanine 2% may represent a safe, effective and inexpensive therapeutic alternative for solar lentigines.
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Affiliation(s)
- A C Katoulis
- Second Department of Dermatology and Venereology, National and Kapodistrian University of Athens, Medical School, Attikon University General Hospital, Athens, Greece.
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Hegge KA, Horning KK, Peitz GJ, Hegge K. Sapropterin: a new therapeutic agent for phenylketonuria. Ann Pharmacother 2009; 43:1466-73. [PMID: 19654333 DOI: 10.1345/aph.1m050] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE To summarize the role of pharmacotherapy in the management of phenylketonuria (PKU) and to review the pharmacology, pharmacokinetics, pharmacodynamics, efficacy data, and safety profile of sapropterin for this indication. DATA SOURCES A literature search was conducted using MEDLINE (1966-May 2009), International Pharmaceutical Abstracts (1970-May 2009), and Cochrane database (2008) for the following key words: sapropterin, tetrahydrobiopterin, phenylketonurias, and phenylalanine. STUDY SELECTION AND DATA EXTRACTION English-language studies involving humans examining the role of tetrahydrobiopterin (BH4) in the management of PKU were reviewed to evaluate the pharmacology, pharmacokinetics, pharmacodynamics, efficacy data, and safety profile for sapropterin. All Phase 2 and 3 randomized controlled trials assessing the safety and efficacy of sapropterin were included in this literature evaluation. DATA SYNTHESIS Sapropterin represents the only Food and Drug Administration-approved medication for BH4-responsive PKU, marking an important advance in the treatment of this condition. Among individuals with hyperphenylalaninemia and some residual phenylalanine hydroxylase function, sapropterin can enhance activity of this enzyme to decrease serum phenylalanine concentrations. Sapropterin has been compared with placebo in one Phase 2 and one Phase 3 clinical trial, demonstrating significantly better response rates. Based on available studies, this agent appears to be safe and well tolerated, with adverse event rates similar to those of placebo. However, additional studies are warranted to assess the long-term safety and efficacy of sapropterin therapy. CONCLUSIONS Sapropterin offers a promising therapeutic option for select individuals with BH4-responsive PKU, although long-term data are limited evaluating its safety and efficacy in traditional clinical practice settings. When considering sapropterin therapy, clinicians must consider factors such as cost and patient adherence to drug therapy and/or diet.
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Affiliation(s)
- Karly A Hegge
- Falls Community Health; College of Pharmacy, South Dakota State University, Sioux Falls, SD 57106, USA.
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18
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Plonka PM, Passeron T, Brenner M, Tobin DJ, Shibahara S, Thomas A, Slominski A, Kadekaro AL, Hershkovitz D, Peters E, Nordlund JJ, Abdel-Malek Z, Takeda K, Paus R, Ortonne JP, Hearing VJ, Schallreuter KU. What are melanocytes really doing all day long...? Exp Dermatol 2009; 18:799-819. [PMID: 19659579 PMCID: PMC2792575 DOI: 10.1111/j.1600-0625.2009.00912.x] [Citation(s) in RCA: 189] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Everyone knows and seems to agree that melanocytes are there to generate melanin - an intriguing, but underestimated multipurpose molecule that is capable of doing far more than providing pigment and UV protection to skin (1). What about the cell that generates melanin, then? Is this dendritic, neural crest-derived cell still serving useful (or even important) functions when no-one looks at the pigmentation of our skin and its appendages and when there is essentially no UV exposure? In other words, what do epidermal and hair follicle melanocytes do in their spare time - at night, under your bedcover? How much of the full portfolio of physiological melanocyte functions in mammalian skin has really been elucidated already? Does the presence or absence of melanocytes matter for normal epidermal and/or hair follicle functions (beyond pigmentation and UV protection), and for skin immune responses? Do melanocytes even deserve as much credit for UV protection as conventional wisdom attributes to them? In which interactions do these promiscuous cells engage with their immediate epithelial environment and who is controlling whom? What lessons might be distilled from looking at lower vertebrate melanophores and at extracutaneous melanocytes in the endeavour to reveal the 'secret identity' of melanocytes? The current Controversies feature explores these far too infrequently posed, biologically and clinically important questions. Complementing a companion viewpoint essay on malignant melanocytes (2), this critical re-examination of melanocyte biology provides a cornucopia of old, but under-appreciated concepts and novel ideas on the slowly emerging complexity of physiological melanocyte functions, and delineates important, thought-provoking questions that remain to be definitively answered by future research.
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Affiliation(s)
- P M Plonka
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, PL-30-387 Kraków, Poland.
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Steventon GB, Mitchell SC. Mouse recombinant phenylalanine monooxygenase and theS-oxygenation of thioether substrates. J Biochem Mol Toxicol 2009; 23:119-24. [DOI: 10.1002/jbt.20274] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Steventon GB, Mitchell SC, Pérez B, Desviat LR, Ugarte M. The activity of wild type and mutant phenylalanine hydroxylase with respect to the C-oxidation of phenylalanine and the S-oxidation of S-carboxymethyl-L-cysteine. Mol Genet Metab 2009; 96:27-31. [PMID: 19036622 DOI: 10.1016/j.ymgme.2008.10.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2008] [Revised: 10/17/2008] [Accepted: 10/17/2008] [Indexed: 10/21/2022]
Abstract
The involvement of the enzyme, phenylalanine hydroxylase (PAH), in the S-oxidation of S-carboxymethyl-L-cysteine (SCMC) is now firmly established in man and rat. However, the underlying role of the molecular genetics of PAH in dictating and influencing the S-oxidation polymorphism of SCMC metabolism is as yet unknown. In this work we report that the S-oxidation of SCMC was dramatically reduced in the tetrahydrobiopterin (BH(4)) responsive mutant PAH proteins (I65T, R68S, R261Q, V388M and Y414C) with these enzymes possessing between 1.2% and 2.0% of the wild type PAH activity when SCMC was used as substrate. These same mutant proteins express between 23% and 76% of the wild type PAH activity when phenylalanine was used as the substrate. The PAH mutant proteins (R158Q, I174T and R408W) that result in the classical phenylketonuria (PKU) phenotype expressing 0.2-1.8% of the wild type PAH activity when using phenylalanine as substrate were found to have <0.1% of the wild type PAH activity when SCMC was used as the substrate. Mutations that result in PAH proteins retaining some residual PAH activity with phenylalanine as substrate have <2.0% residual activity when SCMC was used as a substrate. This investigation has led to the hypothesis that the S-oxidation polymorphism in man is a consequence of an individual carrying one mutant PAH allele which has resulted in the loss of the ability of the residual PAH protein to undertake the S-oxidation of SCMC in vivo.
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Affiliation(s)
- Glyn B Steventon
- King's College London, Pharmaceutical Science Division, Franklin Wilkins Building, 150 Stamford Street, London SE1 9NH, UK.
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Siltberg-Liberles J, Steen IH, Svebak RM, Martinez A. The phylogeny of the aromatic amino acid hydroxylases revisited by characterizing phenylalanine hydroxylase from Dictyostelium discoideum. Gene 2008; 427:86-92. [DOI: 10.1016/j.gene.2008.09.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2008] [Revised: 08/28/2008] [Accepted: 09/01/2008] [Indexed: 10/21/2022]
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Pey AL, Ying M, Cremades N, Velazquez-Campoy A, Scherer T, Thöny B, Sancho J, Martinez A. Identification of pharmacological chaperones as potential therapeutic agents to treat phenylketonuria. J Clin Invest 2008; 118:2858-67. [PMID: 18596920 DOI: 10.1172/jci34355] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Accepted: 05/14/2008] [Indexed: 01/08/2023] Open
Abstract
Phenylketonuria (PKU) is an inborn error of metabolism caused by mutations in phenylalanine hydroxylase (PAH). Over 500 disease-causing mutations have been identified in humans, most of which result in PAH protein misfolding and increased turnover in vivo. The use of pharmacological chaperones to stabilize or promote correct folding of mutant proteins represents a promising new direction in the treatment of misfolding diseases. We performed a high-throughput ligand screen of over 1,000 pharmacological agents and identified 4 compounds (I-IV) that enhanced the thermal stability of PAH and did not show substantial inhibition of PAH activity. In further studies, compounds III (3-amino-2-benzyl-7-nitro-4-(2-quinolyl)-1,2-dihydroisoquinolin-1-one) and IV (5,6-dimethyl-3-(4-methyl-2-pyridinyl)-2-thioxo-2,3-dihydrothieno[2,3- d]pyrimidin-4(1H)-one) stabilized the functional tetrameric conformation of recombinant WT-PAH and PKU mutants. These compounds also significantly increased activity and steady-state PAH protein levels in cells transiently transfected with either WT-PAH or PKU mutants. Furthermore, PAH activity in mouse liver increased after a 12-day oral administration of low doses of compounds III and IV. Thus, we have identified 2 small molecules that may represent promising alternatives in the treatment of PKU.
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Affiliation(s)
- Angel L Pey
- Department of Biomedicine, University of Bergen, Bergen, Norway
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Calvo AC, Pey AL, Ying M, Loer CM, Martinez A. Anabolic function of phenylalanine hydroxylase in Caenorhabditis elegans. FASEB J 2008; 22:3046-58. [PMID: 18460651 DOI: 10.1096/fj.08-108522] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In humans, liver phenylalanine hydroxylase (PAH) has an established catabolic function, and mutations in PAH cause phenylketonuria, a genetic disease characterized by neurological damage, if not treated. To obtain novel evolutionary insights and information on molecular mechanisms operating in phenylketonuria, we investigated PAH in the nematode Caenorhabditis elegans (cePAH), where the enzyme is coded by the pah-1 gene, expressed in the hypodermis. CePAH presents similar molecular and kinetic properties to human PAH [S(0.5)(L-Phe) approximately 150 microM; K(m) for tetrahydrobiopterin (BH(4)) approximately 35 microM and comparable V(max)], but cePAH is devoid of positive cooperativity for L-Phe, an important regulatory mechanism of mammalian PAH that protects the nervous system from excess L-Phe. Pah-1 knockout worms show no obvious neurological defects, but in combination with a second cuticle synthesis mutation, they display serious cuticle abnormalities. We found that pah-1 knockouts lack a yellow-orange pigment in the cuticle, identified as melanin by spectroscopic techniques, and which is detected in C. elegans for the first time. Pah-1 mutants show stimulation of superoxide dismutase activity, suggesting that cuticle melanin functions as oxygen radical scavenger. Our results uncover both an important anabolic function of PAH and the change in regulation of the enzyme along evolution.
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Affiliation(s)
- Ana C Calvo
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009 Bergen, Norway
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Schallreuter KU, Kothari S, Chavan B, Spencer JD. Regulation of melanogenesis--controversies and new concepts. Exp Dermatol 2008; 17:395-404. [PMID: 18177348 DOI: 10.1111/j.1600-0625.2007.00675.x] [Citation(s) in RCA: 232] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Despite many efforts, regulation of skin and hair pigmentation is still not fully understood. This article focuses mainly on controversial aspects in pigment cell biology which have emerged over the last decade. The central role of tyrosinase as the key enzyme in initiation of melanogenesis has been closely associated with the 6BH4 dependent phenylalanine hydroxylase (PAH) and tyrosine hydroxylase isoform I (THI) providing evidence for an old concept of the three enzyme theory in the initiation of the pigmentation process. In this context, it is noteworthy that intracellular L-phenylalanine uptake and turnover to L-tyrosine via PAH is vital for substrate supply of THI and tyrosinase. While PAH acts in the cytosol of melanocytes, THI and tyrosinase are sitting side by side in the melanosomal membrane. THI at low pH provides L-3,4-hydroxyphenylalanine L-DOPA which in turn is required for activation of met-tyrosinase. After an intramelanosomal pH change, possibly by the p-protein, has taken place, tyrosinase is subject to control by 6/7BH4 and the proopiomelanocortin (POMC) peptides alpha-MSH melanocyte stimulating hormone and beta-MSH in a receptor independent manner. cAMP is required for the activation of microphthalmia-associated transcription factor to induce expression of tyrosinase, for transcription of THI and for activation of PAH. The redundancy of the cAMP signal is discussed. Finally, we propose a novel mechanism involving H2O2 in the regulation of tyrosinase via p53 through transcription of hepatocyte nuclear factor 1alpha which in turn can also affect the POMC response.
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Affiliation(s)
- Karin U Schallreuter
- Clinical and Experimental Dermatology/Department of Biomedical Sciences, University of Bradford, Bradford, UK.
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Ralf Paus L, Schallreuter KU, Bahadoran P, Picardo M, Slominski A, Elassiuty YE, Kemp EH, Giachino C, Liu JB, Luiten RM, Lambe T, Le Poole IC, Dammak I, Onay H, Zmijewski MA, Dell’Anna ML, Zeegers MP, Cornall RJ, Paus R, Ortonne JP, Westerhof W. Vitiligo pathogenesis: autoimmune disease, genetic defect, excessive reactive oxygen species, calcium imbalance, or what else? Exp Dermatol 2008. [DOI: 10.1111/j.1600-0625.2007.00666.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Okhrimenko O, Jelesarov I. A survey of the year 2006 literature on applications of isothermal titration calorimetry. J Mol Recognit 2008; 21:1-19. [DOI: 10.1002/jmr.859] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Martinez A, Calvo AC, Teigen K, Pey AL. Rescuing Proteins of Low Kinetic Stability by Chaperones and Natural Ligands: Phenylketonuria, a Case Study. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2008; 83:89-134. [DOI: 10.1016/s0079-6603(08)00603-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Abstract
This article focuses on recent advances in melanocyte biology and physiology. The major function of this neural crest-derived cell is the production of melanins. A "three enzyme theory" in the initiation of pigmentation is put forward and backed up by recent findings. A receptor-independent role for alpha-MSH and the cofactor (6R)-l-erythro-5,6,7,8-terahydrobiopterin (6BH(4)) in the control of tyrosinase is described. The importance of intramelanosomal pH for melanogenesis is covered. Finally, the redundancy of the cAMP and IP3/DAG/calcium signal in melanocytes together with the downstream events are highlighted. The main message of this article is that the intracellular H(2)O(2)- redox-equilibrium controls melanocyte function in a concentration-dependent manner.
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Affiliation(s)
- Karin U Schallreuter
- Clinical and Experimental Dermatology, Department of Biomedical Sciences, University of Bradford, Bradford BD7 1DP, West Yorkshire, UK.
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