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Carpenter EL, Wyant MB, Indra A, Ito S, Wakamatsu K, Merrill GF, Moos PJ, Cassidy PB, Leachman SA, Ganguli-Indra G, Indra AK. Thioredoxin Reductase 1 Modulates Pigmentation and Photobiology of Murine Melanocytes in vivo. J Invest Dermatol 2022; 142:1903-1911.e5. [PMID: 35031135 PMCID: PMC10771865 DOI: 10.1016/j.jid.2021.11.030] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 11/06/2021] [Accepted: 11/19/2021] [Indexed: 12/20/2022]
Abstract
Pigment-producing melanocytes overcome frequent oxidative stress in their physiological role of protecting the skin against the deleterious effects of solar UV irradiation. This is accomplished by the activity of several endogenous antioxidant systems, including the thioredoxin antioxidant system, in which thioredoxin reductase 1 (TR1) plays an important part. To determine whether TR1 contributes to the redox regulation of melanocyte homeostasis, we have generated a selective melanocytic Txnrd1-knockout mouse model (Txnrd1mel‒/‒), which exhibits a depigmentation phenotype consisting of variable amelanotic ventral spotting and reduced pigmentation on the extremities (tail tip, ears, and paws). The antioxidant role of TR1 was further probed in the presence of acute neonatal UVB irradiation, which stimulates melanocyte activation and introduces a spike in oxidative stress in the skin microenvironment. Interestingly, we observed a significant reduction in overall melanocyte count and proliferation in the absence of TR1. Furthermore, melanocytes exhibited an elevated level of UV-induced DNA damage in the form of 8-oxo-2'-deoxyguanosine after acute UVB treatment. We also saw an engagement of compensatory antioxidant mechanisms through increased nuclear localization of transcription factor NRF2. Altogether, these data indicate that melanocytic TR1 positively regulates melanocyte homeostasis and pigmentation during development and protects against UVB-induced DNA damage and oxidative stress.
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Affiliation(s)
- Evan L Carpenter
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon, USA
| | - Mark B Wyant
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon, USA
| | - Aaryan Indra
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon, USA; Corvallis High School, Corvallis, Oregon, USA
| | - Shosuke Ito
- Institute for Melanin Chemistry, Fujita Health University, Toyoake, Aichi, Japan
| | - Kazumasa Wakamatsu
- Institute for Melanin Chemistry, Fujita Health University, Toyoake, Aichi, Japan
| | - Gary F Merrill
- Department of Biochemistry and Biophysics, College of Science, Oregon State University, Corvallis, Oregon, USA
| | - Philip J Moos
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah, Salt Lake City, Utah, USA
| | - Pamela B Cassidy
- Department of Dermatology, Oregon Health & Science University, Portland, Oregon, USA; OHSU Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - Sancy A Leachman
- Department of Dermatology, Oregon Health & Science University, Portland, Oregon, USA; OHSU Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - Gitali Ganguli-Indra
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon, USA; OHSU Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - Arup K Indra
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon, USA; Department of Biochemistry and Biophysics, College of Science, Oregon State University, Corvallis, Oregon, USA; Department of Dermatology, Oregon Health & Science University, Portland, Oregon, USA; OHSU Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, USA; Linus Pauling Institute, Oregon State University, Corvallis, Oregon, USA.
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Youssefi M, Ghazvini K, Casseb J, Keikha M. What is the role of the thioredoxin antioxidant complex in relation to HAM/TSP? Access Microbiol 2020; 2:acmi000090. [PMID: 32974569 PMCID: PMC7470313 DOI: 10.1099/acmi.0.000090] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 12/13/2019] [Indexed: 02/05/2023] Open
Abstract
We have little information about the definite role of the thioredoxin antioxidant complex system during viral infection, particularly during human T-cell lymphotropic virus type 1 (HTLV-1) infection and the HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) state. Therefore, we conducted comprehensive next-generation sequencing (NGS) analysis to determine Trx system expression changes in three categories of subjects: sero-negative HTLV-1 individuals, asymptomatic HTLV-1 people and HAM/TSP patients. We found that Trx capacity is reduced in the HAM/TSP state compared to healthy individuals, which indicates increasing inflammation and reduction of apoptosis, which might contribute to the progression of inflammation in the spinal cord, which in turn may develop into the HAM/TSP state.
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Affiliation(s)
- Masoud Youssefi
- Antimicrobial Resistance Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.,Department of Microbiology and Virology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Kiarash Ghazvini
- Antimicrobial Resistance Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.,Department of Microbiology and Virology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Jorge Casseb
- Department of Dermatology, Institute of Tropical Medicine of São Paulo/ Laboratory of Dermatology and Immunodeficiencies, University of São Paulo Medical School, São Paulo, SP 01246-100, Brazil
| | - Masoud Keikha
- Antimicrobial Resistance Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.,Department of Microbiology and Virology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
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Maddodi N, Jayanthy A, Setaluri V. Shining light on skin pigmentation: the darker and the brighter side of effects of UV radiation. Photochem Photobiol 2012; 88:1075-82. [PMID: 22404235 DOI: 10.1111/j.1751-1097.2012.01138.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The term barrier function as applied to human skin often connotes the physical properties of this organ that provides protection from its surrounding environment. This term does not generally include skin pigmentation. However, skin pigmentation, which is the result of melanin produced in melanocytes residing in the basal layer of the skin and exported to the keratinocytes in the upper layers, serves equally important protective function. Indeed, changes in skin pigmentation are often the most readily recognized indicators of exposure of skin to damaging agents, especially to natural and artificial radiation in the environment. Several recent studies have shed new light on (1) the mechanisms involved in selective effects of subcomponents of UV radiation on human skin pigmentation and (2) the interactive influences between keratinocytes and melanocytes, acting as "epidermal melanin unit," that manifest as changes in skin pigmentation in response to exposure to various forms of radiation. This article provides a concise review of our current understanding of the effects of the nonionizing solar radiation, at cellular and molecular levels, on human skin pigmentation.
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Affiliation(s)
- Nityanand Maddodi
- Department of Dermatology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
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4
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Ufer C, Wang CC, Borchert A, Heydeck D, Kuhn H. Redox control in mammalian embryo development. Antioxid Redox Signal 2010; 13:833-75. [PMID: 20367257 DOI: 10.1089/ars.2009.3044] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The development of an embryo constitutes a complex choreography of regulatory events that underlies precise temporal and spatial control. Throughout this process the embryo encounters ever changing environments, which challenge its metabolism. Oxygen is required for embryogenesis but it also poses a potential hazard via formation of reactive oxygen and reactive nitrogen species (ROS/RNS). These metabolites are capable of modifying macromolecules (lipids, proteins, nucleic acids) and altering their biological functions. On one hand, such modifications may have deleterious consequences and must be counteracted by antioxidant defense systems. On the other hand, ROS/RNS function as essential signal transducers regulating the cellular phenotype. In this context the combined maternal/embryonic redox homeostasis is of major importance and dysregulations in the equilibrium of pro- and antioxidative processes retard embryo development, leading to organ malformation and embryo lethality. Silencing the in vivo expression of pro- and antioxidative enzymes provided deeper insights into the role of the embryonic redox equilibrium. Moreover, novel mechanisms linking the cellular redox homeostasis to gene expression regulation have recently been discovered (oxygen sensing DNA demethylases and protein phosphatases, redox-sensitive microRNAs and transcription factors, moonlighting enzymes of the cellular redox homeostasis) and their contribution to embryo development is critically reviewed.
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Affiliation(s)
- Christoph Ufer
- Institute of Biochemistry, University Medicine Berlin-Charité, Berlin, FR Germany
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Haley B, Paunesku T, Protić M, Woloschak GE. Response of heterogeneous ribonuclear proteins (hnRNP) to ionising radiation and their involvement in DNA damage repair. Int J Radiat Biol 2009; 85:643-55. [PMID: 19579069 DOI: 10.1080/09553000903009548] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
PURPOSE To determine the relationship between heterogeneous nuclear ribonucleoproteins (hnRNP) and DNA repair, particularly in response to ionising radiation (IR). MATERIALS AND METHODS The literature was examined for papers related to the topics of hnRNP, IR and DNA repair. RESULTS HnRNP orchestrate the processing of mRNA to which they are bound in response to IR. HnRNP A18, B1, C1/C2 and K interact with important proteins from DNA Damage Response (DDR) pathways, binding DNA-dependent protein kinase (DNA-PK), the Ku antigen (Ku) and tumour suppressor protein 53 (p53) respectively. Notably, irregularities in the expression of hnRNP A18, B1, K, P2 and L have been linked to cancer and radiosensitivity. Sixteen different hnRNP proteins have been reported to show either mRNA transcript or protein quantity changes following IR. Various protein modifications of hnRNP in response to IR have also been noted: hnRNP A18, C1/C2 and K are phosphorylated; hnRNP C1/C2 is a target of apoptotic proteases; and hnRNP K degradation is controlled by murine double minute ubiquitin ligase (MDM2). Evidence points to a role for hnRNP A1, A18, A2/B1, C1/C2, K and P2 in regulating double-stranded break (DSB) repair pathways by promoting either homologous recombination (HR) or non-homologous end rejoining (NHEJ) repair pathways following IR. CONCLUSIONS HnRNP proteins play a pivotal role in coordinating repair pathways following exposure to IR, through protein-protein interactions and transcript regulation of key repair and stress response mRNA. In particular, several hnRNP proteins are critical in coordinating the choice of HR or NHEJ to repair DSB caused by IR.
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Affiliation(s)
- Benjamin Haley
- Department of Radiation Oncology, Northwestern University, Chicago, Illinois, USA
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7
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Kuhara T, Watanabe D, Akita Y, Takeo T, Ishida N, Nakano A, Yamashita N, Ohshima Y, Kawada M, Yanagishita T, Tamada Y, Matsumoto Y. Thioredoxin upregulation by 5-aminolaevulinic acid-based photodynamic therapy in human skin squamous cell carcinoma cell line. PHOTODERMATOLOGY PHOTOIMMUNOLOGY & PHOTOMEDICINE 2008; 24:142-6. [DOI: 10.1111/j.1600-0781.2008.00354.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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8
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Yang R, Weber DJ, Carrier F. Post-transcriptional regulation of thioredoxin by the stress inducible heterogenous ribonucleoprotein A18. Nucleic Acids Res 2006; 34:1224-36. [PMID: 16513844 PMCID: PMC1388095 DOI: 10.1093/nar/gkj519] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Thioredoxin (TRX) is a key protein of the cellular redox metabolism, which expression is increased in several tumors especially gastric tumors. Even though ultraviolet (UV) and hypoxia specifically induce TRX, the mechanisms that lead to increased TRX levels are still ill defined. Here, we show that the heterogenous ribonucleoprotein A18 (hnRNP A18) RNA Binding Domain (RBD) and the arginine, glycine (RGG) rich domain can bind TRX 3′-untranslated region (3′-UTR) independently but both domains are required for maximal binding. Immunoprecipitation (IP) of hnRNP A18-mRNAs complexes and co-localization of hnRNP A18 and TRX transcripts on ribosomal fractions confirm the interaction of hnRNP A18 with TRX transcripts in cells. Moreover, down regulation of hnRNP A18 correlates with a significant reduction of TRX protein levels. In addition, hnRNP A18 increases TRX translation and interacts with the eukaryotic Initiation Factor 4G (eIF4G), a component of the general translational machinery. Furthermore, hnRNP A18 phosphorylation by the hypoxia inducible GSK3β increases hnRNP A18 RNA binding activity in vitro and in RKO cells in response to UV radiation. These data support a regulatory role for hnRNP A18 in TRX post-transcriptional expression possibly through a kissing loop model bridging TRX 3′- and 5′-UTRs through eIF4G.
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Affiliation(s)
| | | | - France Carrier
- To whom correspondence should be addressed at Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene St. Baltimore, MD 21201, USA. Tel: +1 410 706 5105; Fax: +1 410 706 8297;
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9
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Abstract
Among more than 120 genes that are now known to regulate mammalian pigmentation, one of the key genes is MC1R, which encodes the melanocortin 1 receptor, a seven transmembrane G protein-coupled receptor expressed on the surface of melanocytes. Since the monoexonic sequence of the gene was cloned and characterized more than a decade ago, tremendous efforts have been dedicated to the extensive genotyping of mostly red-haired populations all around the world, thus providing allelic variants that may or may not account for melanoma susceptibility in the presence or absence of ultraviolet (UV) exposure. Soluble factors, such as proopiomelanocortin (POMC) derivatives, agouti signal protein (ASP) and others, regulate MC1R expression, leading to improved photoprotection via increased eumelanin synthesis or in contrast, inducing the switch to pheomelanin. However, there is an obvious lack of knowledge regarding the numerous and complex regulatory mechanisms that govern the expression of MC1R at the intra-cellular level, from gene transcription in response to an external stimulus to the expression of the mature receptor on the melanocyte surface.
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Affiliation(s)
- Francois Rouzaud
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Building 37, Room 2132, Bethesda, MD 20892, USA
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10
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Das DK, Maulik N. Mitochondrial function in cardiomyocytes: target for cardioprotection. Curr Opin Anaesthesiol 2005; 18:77-82. [PMID: 16534320 DOI: 10.1097/00001503-200502000-00012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW Cardiac diseases including ischemic heart disease, cardiomyopathy, hypertension, atherosclerosis and congestive heart failure are associated with cardiac cell death as a result of both necrosis and apoptosis. Mitochondria play an essential role in deciding whether a cell lives or dies. This review summarizes current knowledge on the mechanisms by which mitochondria exert such decision-making power. RECENT FINDINGS A wide variety of factors, either directly or indirectly, function in a synchronized manner to regulate the death versus survival signals. Mitochondrial bioenergetics and permeability transition pore plays a crucial role in this process, although several redox-sensitive genes, proteins and transcription factors, such as Bcl-2, Bax, nuclear factor kappa B, regulate the decision-making power of mitochondria, which have the final authority to decide whether a cell lives or dies. Mitochondrially generated reactive oxygen species are critically involved in the decision-making process, by functioning both as executioner by damaging the biomolecules, or as savior by virtue of their ability to perform redox signaling. SUMMARY It appears that mitochondria regulate the life and death of cardiac cells by manipulating several factors, including bioenergetics, mitochondrial permeability transition pore and redox-sensing genes. Redox signaling is likely to be critically involved in this process.
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Affiliation(s)
- Dipak K Das
- Cardiovascular Research Center, University of Connecticut School of Medicine, Farmington, Connecticut 06030-1110, USA.
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11
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Abstract
Thioredoxins are a class of small redox-regulating proteins that appear to play a crucial role in many oxidative stress-inducible degenerative diseases. A recent study demonstrated a reduction of thioredoxin-1 (Trx1) protein in the ischemic reperfused myocardium. When the same heart was adapted to ischemic stress by preconditioning with repeated cyclic episodes of small duration of ischemia and reperfusion, there was an increased induction of Trx1 expression. Inhibition of Trx1 expression resulted in reduced postischemic ventricular recovery and increased myocardial infarct size in the preconditioned heart. Corroborating these findings, transgenic mouse hearts overexpressing Trx1 were resistant to ischemic reperfusion injury as compared with the hearts from wild-type mice. Thus, it appears that thioredoxin plays a crucial role in cardioprotection induced by preconditioning.
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Affiliation(s)
- Dipak K Das
- Cardiovascular Research Center, University of Connecticut School of Medicine, Farmington, CT, USA.
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12
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Yang C, Carrier F. The UV-inducible RNA-binding protein A18 (A18 hnRNP) plays a protective role in the genotoxic stress response. J Biol Chem 2001; 276:47277-84. [PMID: 11574538 DOI: 10.1074/jbc.m105396200] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
We have previously shown that specific RNA-binding proteins (RBP) are activated by genotoxic stress. The role and function of these stress-activated RBP are, however, poorly understood. The data presented here indicate that the RBP A18 heterogeneous ribonucleoprotein (hnRNP) is induced and translocated from the nuclei to the cytoplasm after exposure to UV radiation. Using a new in vitro system we identified potential cellular targets for A18 hnRNP. Forty-six mRNA transcripts were identified, most of which are stress- or UV-responsive genes. Two important stress-responsive transcripts, the replication protein A (RPA2) and thioredoxin, were studied in more detail. Northwestern analyses indicate that A18 hnRNP binds specifically to the 3'-untranslated region of RPA2 transcript independently of its poly(A) tail, whereas the poly(A) tail of thioredoxin mRNA reinforces binding. Overexpression of A18 hnRNP increases the mRNAs stability and consequently enhances translation in a dose-dependent manner. Moreover, cell lines expressing reduced levels of A18 hnRNP are more sensitive to UV radiation. These data suggest that A18 hnRNP plays a protective role against genotoxic stresses by translocating to the cytosol and stabilizing specific transcripts involved in cell survival.
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MESH Headings
- 3' Untranslated Regions
- 5' Untranslated Regions
- Blotting, Northern
- Blotting, Western
- Cell Division
- Cell Line
- Cell Nucleus/radiation effects
- Cell Survival
- Chloramphenicol O-Acetyltransferase/metabolism
- Cytoplasm/radiation effects
- DNA, Complementary/metabolism
- DNA-Binding Proteins/metabolism
- Dose-Response Relationship, Drug
- Dose-Response Relationship, Radiation
- Heterogeneous-Nuclear Ribonucleoproteins
- Humans
- Microscopy, Fluorescence
- Models, Genetic
- Open Reading Frames
- Plasmids/metabolism
- Poly A
- Protein Biosynthesis
- Protein Transport/radiation effects
- RNA, Messenger/metabolism
- RNA-Binding Proteins/chemistry
- RNA-Binding Proteins/physiology
- Recombinant Fusion Proteins/metabolism
- Replication Protein A
- Ribonucleoproteins/chemistry
- Ribonucleoproteins/physiology
- Stress, Physiological
- Time Factors
- Transcription, Genetic
- Tumor Cells, Cultured
- Ultraviolet Rays
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Affiliation(s)
- C Yang
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene St., Baltimore, MD 21201-1503, USA
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13
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Funasaka Y, Chakraborty AK, Yodoi J, Ichihashi M. The effect of thioredoxin on the expression of proopiomelanocortin-derived peptides, the melanocortin 1 receptor and cell survival of normal human keratinocytes. J Investig Dermatol Symp Proc 2001; 6:32-7. [PMID: 11764282 DOI: 10.1046/j.0022-202x.2001.00002.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
An important constituent of the cellular antioxidant buffering system that controls the redox state of proteins is thioredoxin (TRX), a 13 kDa protein that catalyzes thiol-disulfide exchange reactions, regulates activation of transcription factors, and possesses several other biologic functions similar to cytokines. We have previously reported that TRX released from UVB-irradiated keratinocytes stimulates melanogenesis by upregulating MSH receptor expression and its binding activity in melanocytes. The purpose of this study was to examine the effects of TRX on keratinocytes as an autocrine factor. TRX suppressed the UVB-induced production and secretion of alpha-melanocyte stimulating hormone (alpha-MSH) and of adrenocorticotropic hormone (ACTH), and also suppressed proopiomelanocortin (POMC) mRNA expression by normal human keratinocytes; however, TRX upregulated melanocortin 1 receptor (MC1-R) expression synergistically with UVB in normal human keratinocytes. These results suggest that exogenous TRX regulates expression of those genes in different manners. Furthermore, addition of an antibody against TRX induced cell death in keratinocytes, probably due to enhanced signaling of MSH, as it has been shown that MSH suppresses heat shock protein (hsp) 70 expression in differentiated keratinocytes, which express high levels of MC1-R and decreases their survival rate during oxidative stress. Taken together, the results suggest that keratinocyte-derived TRX regulates the expression of stress inducible neuropeptides and their receptor, and is critically involved in the survival of keratinocytes.
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Affiliation(s)
- Y Funasaka
- Department of Dermatology, Kobe University School of Medicine, Japan.
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14
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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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15
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Moro O, Ideta R, Ifuku O. Characterization of the promoter region of the human melanocortin-1 receptor (MC1R) gene. Biochem Biophys Res Commun 1999; 262:452-60. [PMID: 10462496 DOI: 10.1006/bbrc.1999.1228] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We sequenced 3201 bp upstream from the ATG translation start codon of the human melanocortin-1 receptor (MC1R). A number of transcriptional initiation sites were detected over a region of approximately 600 base pairs upstream of the receptor coding region. These consist of GC-rich regions, each including SP-1 consensus binding motifs. Neither a TATA nor a CAAT box was found in this region. The 5'-flanking region also contains the consensus regulatory elements for AP-1, AP-2, and several E-boxes. Gel shift assays targeting the three GC boxes confirmed binding of SP-1. A promoter assay revealed that the minimal region exhibiting promoter activity was located between nucleotides -517 and -282 in human melanoma SK-Mel-2 cells. Further deletion from -517 to -447, which removed an SP-1 site, completely abolished luciferase activity. In conclusion, the MC1R promoter shares the characteristics of many other GPCR promoters. These characteristics include GC-rich sequence, lack of a TATA box, and binding of SP-1.
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Affiliation(s)
- O Moro
- Shiseido Research Center, 1050 Nippa-cho, Kohoku-ku, Yokohama-shi, Kanagawa, 223-8553, Japan.
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16
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Chakraborty AK, Funasaka Y, Pawelek JM, Nagahama M, Ito A, Ichihashi M. Enhanced expression of melanocortin-1 receptor (MC1-R) in normal human keratinocytes during differentiation: evidence for increased expression of POMC peptides near suprabasal layer of epidermis. J Invest Dermatol 1999; 112:853-60. [PMID: 10383729 DOI: 10.1046/j.1523-1747.1999.00608.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Immunohistochemical staining of human skin specimen showed the stronger localization of proopiomelanocortin peptides near the suprabasal layer of the epidermis, where keratinocytes are mostly differentiated. To test the possibilities of whether the production of proopiomelanocortin peptides or their receptor-binding activity or both is increased during differentiation of keratinocytes, we treated the cells in culture with Ca2+ to induce their differentiation. The production of proopiomelanocortin peptides and its gene expression were not induced significantly, but the binding ability of melanocortin receptor, as well as its gene expression were stimulated by Ca2+. Ultraviolet B irradiation, an inducer of differentiation, stimulated both proopiomelanocortin production and melanocortin receptor expression. These data show that normal human keratinocytes express melanocortin receptor similar to melanocytes, and that it is induced during differentiation.
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Affiliation(s)
- A K Chakraborty
- Department of Dermatology, Kobe University School of Medicine, Japan
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17
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Abstract
Oxidation-reduction (redox) based regulation of signal transduction and gene expression is emerging as a fundamental regulatory mechanism in cell biology. Electron flow through side chain functional CH2-SH groups of conserved cysteinyl residues in proteins account for their redox-sensing properties. Because in most intracellular proteins thiol groups are strongly "buffered" against oxidation by the highly reduced environment inside the cell, only accessible protein thiol groups with high thiol-disulfide oxidation potentials are likely to be redox sensitive. The list of redox-sensitive signal transduction pathways is steadily growing, and current information suggests that manipulation of the cell redox state may prove to be an important strategy for the management of AIDS and some forms of cancer. The endogenous thioredoxin and glutathione systems are of central importance in redox signaling. Among the thiol agents tested for their efficacy to modulate cellular redox status, N-acetyl-L-cysteine (NAC) and alpha-lipoic acid hold promise for clinical use. A unique advantage of lipoate is that it is able to utilize cellular reducing equivalents, and thus it harnesses the metabolic power of the cell to continuously regenerate its reductive vicinal dithiol form. Because lipoate can be readily recycled in the cell, it has an advantage over N-acetyl-L-cysteine on a concentration:effect basis. Our current knowledge of redox regulated signal transduction has led to the unfolding of the remarkable therapeutic potential of cellular thiol modulating agents.
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Affiliation(s)
- C K Sen
- Department of Molecular and Cell Biology, University of California, Berkeley 94720-3200, USA.
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