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Kang DY, Kim HC. Functional relation of agouti signaling proteins (ASIPs) to pigmentation and color change in the starry flounder, Platichthys stellatus. Comp Biochem Physiol A Mol Integr Physiol 2024; 291:111524. [PMID: 37981006 DOI: 10.1016/j.cbpa.2023.111524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 09/30/2023] [Accepted: 10/01/2023] [Indexed: 11/21/2023]
Abstract
We investigated the involvement of agouti-signaling proteins (ASIPs) in morphological pigmentation and physiological color change in flatfishes. We isolated ASIP1 and 2 mRNAs from the skin of starry flounder (Platichthys stellatus), and compared their amino acid (aa) structures to those of other animals. Then, we examined the mRNA expression levels of two ASIPs (Sf-ASIPs) in the pigmented ocular body and in the unpigmented blind body, as well as in the ordinary skin and in albino skin, in flatfishes. To investigate the role of Sf-ASIPs in physiological color change (color camouflage), we compared the expression of the two genes in two background colors (dark-green and white). Sf-ASIP1 cDNA had a 375-bp open reading frame (ORF) that encoded a protein consisting of 125 aa residues, and Sf-ASIP2 cDNA had a 402-bp ORF that encoded a protein consisting of 132 aa residues. RT-PCR revealed that the strongest Sf-ASIP1 and Sf-ASIP2 expression levels were observed in the eye and blind-skin, respectively. In Sf-ASIP1, the gene expression did not differ between the ocular-side skin and blind-side skin, nor between ordinary skin and abnormal skin of the fish. However, in Sf-ASIP2, the expression level was significantly higher in blind-side skin, compared to ocular-side skin, suggesting that the ASIP2 gene is related to the countershading body pigment pattern of the fish. In addition, the Sf-ASIP2 gene expression level was lower in the pigmented spot regions than in the unpigmented spot regions of the malpigmented pseudo-albino skins on the ocular side, implying that ASIP2 is responsible for the ocular-side pseudo-albino. Additionally, ASIP2 gene expression in the blind-side skin of ordinary fish was enhanced by a white tank, implying that a bright background color could inhibit hypermelanosis in the blind-side skin of cultured flounder by increasing the activity of the Sf-ASIP2 gene. However, we did not find any relationship of ASIPs with camouflage color changes. In conclusion, the ASIP2 gene is related to the morphological pigmentation (countershading and malpigmentation) of the skin in starry flounder, but not with physiological color changes (color camouflage) in the ocular-side skin.
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Affiliation(s)
- Duk-Young Kang
- National Institute of Fisheries Science, West Sea Fisheries Research Institute, 707 Eulwang-dong, Jung-gu, Incheon, Republic of Korea.
| | - Hyo-Chan Kim
- KMS & MC, Molecular research, Haneulbyeolbit-ro, YoungJong-1 dong, Joong-gu, Incheon, Republic of Korea
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Yao YZ, Liao ZK, Jiang S, Dong BQ, Luo LF, Miao F, Lei TC. Uncoupling melanogenesis from proliferation in epidermal melanocytes responding to stimulation with psoriasis-related proinflammatory cytokines. J Dermatol Sci 2022; 108:98-108. [PMID: 36577564 DOI: 10.1016/j.jdermsci.2022.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 11/17/2022] [Accepted: 11/23/2022] [Indexed: 12/23/2022]
Abstract
BACKGROUND Few studies have addressed the impact of the psoriasis-related proinflammatory cytokines on the proliferation and melanogenesis of melanocytes (MCs) in lesional psoriatic skin. OBJECTIVE We investigated the effects of TNFα, IL17A, and IL8 on the proliferation and melanin synthesis of MCs. METHODS Skin specimens were biopsied from patients with psoriasis vulgaris at the active stage, or from the tail skin of Dct-LacZ mice with imiquimod (IMQ)-induced psoriasiform dermatitis. Cultured keratinocytes (KCs), MCs, and human skin explants were used in this study. The numbers of MCs were measured via β-galactosidase staining, EdU incorporation and HMB45 immunohistochemical staining. The expression of human β-defensin 3 (hBD3) in KCs was silenced by siRNA, the conditioned medium (CM) from siRNA-transfected KCs was used to treat MCs, then followed by αMSH stimulation. The melanogenesis-related genes were examined by using qRT-PCR and western blotting. RESULTS The increased number of MCs and decreased melanin content were highly relevant to the enhanced expression of IL8 and BD3 both in human psoriatic skin and in IMQ-treated mouse tail skin. IL8 expression in KCs and CXCR2 expression in MCs was significantly increased by IL17A and TNFα, the αMSH-induced upregulations of microphthalmia-associated transcription factor (MITF) and tyrosinase in MCs were abrogated by the CM from hBD3-unsilenced KCs, but not from hBD3-silenced KCs. CONCLUSION Our results suggest the roles of IL8-CXCR2 activation in promoting MC proliferation and of BD3 upregulation in reducing melanogenesis. These findings have been implicated in the underlying mechanism that active psoriasis prefers hypopigmentation despite chronic inflammation.
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Affiliation(s)
- Yun-Zhu Yao
- Department of Dermatology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Zhi-Kai Liao
- Department of Dermatology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Shan Jiang
- Department of Dermatology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Bing-Qi Dong
- Department of Dermatology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Long-Fei Luo
- Department of Dermatology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Fang Miao
- Department of Dermatology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Tie-Chi Lei
- Department of Dermatology, Renmin Hospital of Wuhan University, Wuhan, China.
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Shi ML, Xu P, Yin XS, Yang WW, Gu ME, Yu LP, Liu GJ, Wu BJ. [Phenotype analysis and mutant gene location of ventral yellow mouse (VY(Slac))]. DONG WU XUE YAN JIU = ZOOLOGICAL RESEARCH 2012; 33:290-7. [PMID: 22653857 DOI: 10.3724/sp.j.1141.2012.03290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The ventri-yellow pigmentation mouse (temporarily named VY(Slac)) arose spontaneously in the C57BL/6J inbred mouse strain, found and bred by Shanghai SLAC Laboratory Animal Co., Ltd. VY(Slac) presented a special phenotype marked by yellow coat on the ventral surface of neck and trunk that was without melanin deposition but maintained a normal structure. The number of melanocytes in epidermis and melanin in hair follicle of the abdominal skin of the mutant mouse were less than that of their background strain, while there was no significant difference between the dorsal skins of the two strains. This mutant phenotype was inherited as single-gene dominant inheritance, confirmed by genetic experiment, and there was no significant difference between VY(Slac) and B(6) for other biological parameters such as weight, anatomic and histological structures of major organs and blood physiology. When the linkage relationship between the genomic DNA samples of F(2) 48 mice (VY(Slac)D(2)F(1)×D(2)) and mutant phenotype were evaluated, the mutant gene was confirmed on chromosome 2 near D2Mit229. New microsatellite and SNP markers were selected to amplify genomic DNA samples of 196 F(2) mice and the mutant gene was narrowed down to 5.3 Mb region between rs13476833 and rs27310903 on chromosome 2. The preliminary results of our phenotype analysis and gene location provides a solid basis for further identification of this mutant gene.
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Affiliation(s)
- Mei-Lian Shi
- Shanghai SLAC Laboratory Animal Co., Ltd., Shanghai,China
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4
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Albrecht E, Komolka K, Kuzinski J, Maak S. Agouti revisited: transcript quantification of the ASIP gene in bovine tissues related to protein expression and localization. PLoS One 2012; 7:e35282. [PMID: 22530003 PMCID: PMC3328439 DOI: 10.1371/journal.pone.0035282] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Accepted: 03/14/2012] [Indexed: 02/07/2023] Open
Abstract
Beside its role in melanogenesis, the agouti signaling protein (ASIP) has been related to obesity. The potentially crucial role in adipocyte development makes it a tempting candidate for economic relevant, fat related traits in farm animals. The objective of our study was to characterize the mRNA expression of different ASIP transcripts and of putative targets in different bovine tissues, as well as to study consequences on protein abundance and localization. ASIP mRNA abundance was determined by RT-qPCR in adipose and further tissues of cattle representing different breeds and crosses. ASIP mRNA was up-regulated more than 9-fold in intramuscular fat of Japanese Black cattle compared to Holstein (p<0.001). Further analyses revealed that a transposon-derived transcript was solely responsible for the increased ASIP mRNA abundance. This transcript was observed in single individuals of different breeds indicating a wide spread occurrence of this insertion at the ASIP locus in cattle. The protein was detected in different adipose tissues, skin, lung and liver, but not in skeletal muscle by Western blot with a bovine-specific ASIP antibody. However, the protein abundance was not related to the observed ASIP mRNA over-expression. Immuno-histochemical analyses revealed a putative nuclear localization of ASIP additionally to the expected cytosolic signal in different cell types. The expression of melanocortin receptors (MCR) 1 to 5 as potential targets for ASIP was analyzed by RT-PCR in subcutaneous fat. Only MC1R and MC4R were detected indicating a similar receptor expression like in human adipose tissue. Our results provide evidence for a widespread expression of ASIP in bovine tissues at mRNA and, for the first time, at protein level. ASIP protein is detectable in adipocytes as well as in further cells of adipose tissue. We generated a basis for a more detailed investigation of ASIP function in peripheral tissues of various mammalian species.
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Affiliation(s)
- Elke Albrecht
- Research Unit Muscle Biology and Growth, Leibniz Institute for Farm Animal Biology, Dummerstorf, Germany
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5
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Cerdá-Reverter JM, Agulleiro MJ, R RG, Sánchez E, Ceinos R, Rotllant J. Fish melanocortin system. Eur J Pharmacol 2011; 660:53-60. [DOI: 10.1016/j.ejphar.2010.10.108] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2010] [Revised: 09/30/2010] [Accepted: 10/12/2010] [Indexed: 12/26/2022]
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Kanasaki K, Koya D. Biology of obesity: lessons from animal models of obesity. J Biomed Biotechnol 2011; 2011:197636. [PMID: 21274264 PMCID: PMC3022217 DOI: 10.1155/2011/197636] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Accepted: 12/13/2010] [Indexed: 12/17/2022] Open
Abstract
Obesity is an epidemic problem in the world and is associated with several health problems, including diabetes, cardiovascular disease, respiratory failure, muscle weakness, and cancer. The precise molecular mechanisms by which obesity induces these health problems are not yet clear. To better understand the pathomechanisms of human disease, good animal models are essential. In this paper, we will analyze animal models of obesity and their use in the research of obesity-associated human health conditions and diseases such as diabetes, cancer, and obstructive sleep apnea syndrome.
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Affiliation(s)
- Keizo Kanasaki
- Division of Diabetes & Endocrinology, Kanazawa Medical University, Uchinada, Ishikawa 920-0293, Japan
| | - Daisuke Koya
- Division of Diabetes & Endocrinology, Kanazawa Medical University, Uchinada, Ishikawa 920-0293, Japan
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7
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Antibodies specific to melanocyte-specific proteins available from the Hearing Laboratory. Pigment Cell Melanoma Res 2009. [DOI: 10.1111/j.1755-148x.2009.00601.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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8
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Passeron T, Coelho SG, Miyamura Y, Takahashi K, Hearing VJ. Immunohistochemistry and in situ hybridization in the study of human skin melanocytes. Exp Dermatol 2007; 16:162-70. [PMID: 17286807 DOI: 10.1111/j.1600-0625.2006.00538.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Although keratinocytes are the most numerous type of cell in the skin, melanocytes are also key players as they produce and distribute melanin that protects the skin from ultraviolet (UV) radiation. In vitro experiments on melanocytic cell lines are useful to study melanogenesis and their progression towards melanoma. However, interactions of melanocytes with keratinocytes and with other types of cells in the skin, such as fibroblasts and Langerhans cells, are also crucial. We describe two techniques, immunohistochemistry (IHC) and tissue in situ hybridization (TISH), that can be used to identify and study melanocytes in the skin and their responses to UV or other stimuli in situ. We describe a practical method to localize melanocytic antigens on formalin-fixed, paraffin-embedded tissue sections and in frozen sections using indirect immunofluorescence with conjugated secondary antibodies. In addition, we detail the use of TISH and its combination with IHC to study mRNA levels of genes expressed in the skin at cellular resolution. This methodology, along with relevant tips and troubleshooting items, are important tools to identify and study melanocytes in the skin.
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Affiliation(s)
- Thierry Passeron
- Pigment Cell Biology Section, Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Abstract
Insights into the etiology of human obesity have arisen from the study of animal models. Animal models of obesity are also important for the development of future treatments of obesity. An agouti mouse mutation resulting in obese, yellow mice was described over a century ago and in 1992 agouti was cloned, making it the first obesity gene characterized at the molecular level. The lethal yellow mouse mutation is one of five dominant agouti mutations and is an excellent model for human obesity. The molecular categorization of agouti was responsible for the elucidation of the melanocortin system's involvement in hypothalamic weight regulation. As genetic knowledge increases many transgenic mice have been created with genes either over-expressed or deleted, models which further enhance the understanding of obesity.
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Affiliation(s)
- Levi Carroll
- Co-operative Research Centre for Diagnostics, School of Life Sciences, Queensland University of Technology, Brisbane, Australia
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10
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Kuklin AI, Mynatt RL, Klebig ML, Kiefer LL, Wilkison WO, Woychik RP, Michaud EJ. Liver-specific expression of the agouti gene in transgenic mice promotes liver carcinogenesis in the absence of obesity and diabetes. Mol Cancer 2004; 3:17. [PMID: 15175105 PMCID: PMC443512 DOI: 10.1186/1476-4598-3-17] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2004] [Accepted: 06/02/2004] [Indexed: 11/25/2022] Open
Abstract
Background The agouti protein is a paracrine factor that is normally present in the skin of many species of mammals. Agouti regulates the switch between black and yellow hair pigmentation by signalling through the melanocortin 1 receptor (Mc1r) on melanocytes. Lethal yellow (Ay) and viable yellow (Avy) are dominant regulatory mutations in the mouse agouti gene that cause the wild-type protein to be produced at abnormally high levels throughout the body. Mice harboring these mutations exhibit a pleiotropic syndrome characterized by yellow coat color, obesity, hyperglycemia, hyperinsulinemia, and increased susceptibility to hyperplasia and carcinogenesis in numerous tissues, including the liver. The goal of this research was to determine if ectopic expression of the agouti gene in the liver alone is sufficient to recapitulate any aspect of this syndrome. For this purpose, we generated lines of transgenic mice expressing high levels of agouti in the liver under the regulatory control of the albumin promoter. Expression levels of the agouti transgene in the liver were quantified by Northern blot analysis. Functional agouti protein in the liver of transgenic mice was assayed by its ability to inhibit binding of the α-melanocyte stimulating hormone (αMSH) to the Mc1r. Body weight, plasma insulin and blood glucose levels were analyzed in control and transgenic mice. Control and transgenic male mice were given a single intraperitoneal injection (10 mg/kg) of the hepatocellular carcinogen, diethylnitrosamine (DEN), at 15 days of age. Mice were euthanized at 36 or 40 weeks after DEN injection and the number of tumors per liver and total liver weights were recorded. Results The albumin-agouti transgene was expressed at high levels in the livers of mice and produced a functional agouti protein. Albumin-agouti transgenic mice had normal body weights and normal levels of blood glucose and plasma insulin, but responded to chemical initiation of the liver with an increased number of liver tumors compared to non-transgenic control mice. Conclusions The data demonstrate that liver-specific expression of the agouti gene is not sufficient to induce obesity or diabetes, but, in the absence of these factors, agouti continues to promote hepatocellular carcinogenesis.
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Affiliation(s)
- Alexander I Kuklin
- Life Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831, USA
- Transgenomic, Inc., 12325 Emmet Street, Omaha, NE 68164, USA
| | - Randall L Mynatt
- Life Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831, USA
- Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, LA 70808, USA
| | - Mitchell L Klebig
- Life Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831, USA
- Department of Biochemistry and Cellular & Molecular Biology, The University of Tennessee, Knoxville, TN 37996, USA
| | - Laura L Kiefer
- Glaxo Wellcome, 5 Moore Drive, Research Triangle Park, NC 27709, USA
- Paradigm Genetics, 108 Alexander Drive, Research Triangle Park, NC 27709, USA
| | - William O Wilkison
- Glaxo Wellcome, 5 Moore Drive, Research Triangle Park, NC 27709, USA
- GlaxoSmithKline, Inc., 5 Moore Drive, Research Triangle Park, NC 27709, USA
| | - Richard P Woychik
- Life Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831, USA
- The Jackson Laboratory, 600 Main Street, Bar Harbor, ME 04609, USA
| | - Edward J Michaud
- Life Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831, USA
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Voisey J, Imbeault P, Hutley L, Prins JB, van Daal A. Body mass index-related human adipocyte agouti expression is sex-specific but not depot-specific. OBESITY RESEARCH 2002; 10:447-52. [PMID: 12055320 DOI: 10.1038/oby.2002.62] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE To determine if human adipocyte agouti signal protein (ASIP) mRNA expression is associated with obesity and is gender and/or depot specific. RESEARCH METHODS AND PROCEDURES Subjects included 8 men (64 +/- 3 years) and 14 women (56 +/- 15 years) undergoing elective abdominal surgery. ASIP mRNA levels in isolated omental and subcutaneous abdominal adipocytes were measured by quantitative reverse transcription polymerase chain reaction. RESULTS No significant depot difference was observed between genders; ASIP mRNA levels of omental and subcutaneous abdominal adipocytes were pooled for this analysis. BMI and ASIP gene expression were negatively correlated in men (rho = -0.70; p < 0.05), whereas a positive relationship was observed in women (rho = 0.48; p < 0.05). No significant difference was observed in age, body weight, body mass index (BMI), and waist circumference between groups. Hip circumference was significantly higher in women than in men (p < 0.05). Also, no significant difference in ASIP mRNA expression was observed between men and women, regardless of the fat depot. DISCUSSION These results show that men and women of similar age and BMI present similar ASIP mRNA levels in omental and subcutaneous abdominal adipocytes. However, a sexual dimorphism exists in the relationship between ASIP expression and BMI. If ASIP is involved in appetite regulation or energy homeostasis in humans, this observation may contribute to the recognized differences in these parameters between men and women.
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Affiliation(s)
- Joanne Voisey
- Cooperative Research Centre for Diagnostic Technologies, Queensland University of Technology, Brisbane, Australia
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12
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Abstract
The agouti protein regulates pigmentation in the mouse hair follicle producing a black hair with a subapical yellow band. Its effect on pigmentation is achieved by antagonizing the binding of alpha-melanocyte stimulating hormone (alpha-MSH) to melanocortin 1 receptor (Mc1r), switching melanin synthesis from eumelanin (black/brown) to phaeomelanin (red/yellow). Dominant mutations in the non-coding region of mouse agouti cause yellow coat colour and ectopic expression also results in obesity, type 11 diabetes, increased somatic growth and tumourigenesis. At least some of these pleiotropic effects can be explained by antagonism of other members of the melanocortin receptor family by agouti protein. The yellow coat colour is the result of agouti chronically antagonizing the binding of alpha-MSH to Mc1r and the obese phenotype results from agouti protein antagonizing the binding of alpha-MSH to Mc3r and/or Mc4r. Despite the existence of a highly homologous agouti protein in humans, agouti signal protein (ASIP), its role has yet to be defined. However it is known that human ASIP is expressed at highest levels in adipose tissue where it may antagonize one of the melanocortin receptors. The conserved nature of the agouti protein combined with the diverse phenotypic effects of agouti mutations in mouse and the different expression patterns of human and mouse agouti, suggest ASIP may play a role in human energy homeostasis and possibly human pigmentation.
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Affiliation(s)
- Joanne Voisey
- Co-operative Research Centre for Diagnostics, Queensland University of Technology, Brisbane, Australia
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13
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Miltenberger RJ, Wakamatsu K, Ito S, Woychik RP, Russell LB, Michaud EJ. Molecular and phenotypic analysis of 25 recessive, homozygous-viable alleles at the mouse agouti locus. Genetics 2002; 160:659-74. [PMID: 11861569 PMCID: PMC1461996 DOI: 10.1093/genetics/160.2.659] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Agouti is a paracrine-acting, transient antagonist of melanocortin 1 receptors that specifies the subapical band of yellow on otherwise black hairs of the wild-type coat. To better understand both agouti structure/function and the germline damage caused by chemicals and radiation, an allelic series of 25 recessive, homozygous-viable agouti mutations generated in specific-locus tests were characterized. Visual inspection of fur, augmented by quantifiable chemical analysis of hair melanins, suggested four phenotypic categories (mild, moderate, umbrous-like, severe) for the 18 hypomorphs and a single category for the 7 amorphs (null). Molecular analysis indicated protein-coding alterations in 8 hypomorphs and 6 amorphs, with mild-moderate phenotypes correlating with signal peptide or basic domain mutations, and more devastating phenotypes resulting from C-terminal lesions. Ten hypomorphs and one null demonstrated wild-type coding potential, suggesting that they contain mutations elsewhere in the > or = 125-kb agouti locus that either reduce the level or alter the temporal/spatial distribution of agouti transcripts. Beyond the notable contributions to the field of mouse germ cell mutagenesis, analysis of this allelic series illustrates that complete abrogation of agouti function in vivo occurs most often through protein-coding lesions, whereas partial loss of function occurs slightly more frequently at the level of gene expression control.
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14
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Furumura M, Potterf SB, Toyofuku K, Matsunaga J, Muller J, Hearing VJ. Involvement of ITF2 in the transcriptional regulation of melanogenic genes. J Biol Chem 2001; 276:28147-54. [PMID: 11382753 DOI: 10.1074/jbc.m101626200] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In response to agouti signal protein, melanocytes switch from producing eumelanin to pheomelanin concomitant with the down-regulation of melanogenic gene transcription. We previously reported that a ubiquitous basic helix-loop-helix transcription factor, known as ITF2, is up-regulated during this switch, and we now report that treatment of melanocytes with melanocyte-stimulating hormone down-regulates expression of ITF2. To more fully characterize the involvement of ITF2 in regulating melanogenic gene transcription, ITF2 sense or antisense constructs were introduced into melan-a melanocytes. Gene and protein expression analyses and luciferase reporter assays using promoters from melanogenic genes showed that up-regulation of ITF2 suppressed melanogenic gene expression as well as the expression of Mitf, a melanocyte-specific transcription factor. In addition, stable ITF2 sense transfectants had significant reductions in pigmentation and a less dendritic phenotype compared with mock transfectants. In contrast, ITF2 antisense-transfected melanocytes were more pigmented and more dendritic. These results demonstrate that up-regulation of ITF2 during the pheomelanin switch is functionally significant and reveal that differential expression of a ubiquitous basic helix-loop-helix transcription factor can modulate expression of melanogenic genes and the differentiation of melanocytes.
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MESH Headings
- Animals
- Antigens, Neoplasm
- Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
- Blotting, Northern
- Cell Differentiation
- Cyclic AMP/metabolism
- DNA-Binding Proteins/chemistry
- DNA-Binding Proteins/physiology
- Dendritic Cells/metabolism
- Down-Regulation
- Genes, Reporter
- Helix-Loop-Helix Motifs
- Luciferases/metabolism
- MART-1 Antigen
- Melanins/metabolism
- Melanocytes/metabolism
- Mice
- Mice, Inbred C3H
- Mice, Inbred C57BL
- Microscopy, Electron
- Models, Biological
- Neoplasm Proteins/metabolism
- Nerve Tissue Proteins
- Oligonucleotides, Antisense/metabolism
- Phenotype
- Plasmids/metabolism
- Precipitin Tests
- Promoter Regions, Genetic
- Protein Isoforms
- RNA, Messenger/metabolism
- Ribonucleases/metabolism
- TCF Transcription Factors
- Trans-Activators/chemistry
- Trans-Activators/physiology
- Transcription Factor 4
- Transcription Factors/metabolism
- Transcription, Genetic
- Transfection
- Up-Regulation
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Affiliation(s)
- M Furumura
- Pigment Cell Biology Section, Laboratory of Cell Biology, NCI, National Institutes of Health, Bethesda, Maryland 20892, USA
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15
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Wikberg JE, Muceniece R, Mandrika I, Prusis P, Lindblom J, Post C, Skottner A. New aspects on the melanocortins and their receptors. Pharmacol Res 2000; 42:393-420. [PMID: 11023702 DOI: 10.1006/phrs.2000.0725] [Citation(s) in RCA: 257] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Knowledge of melanocortins and their receptors has increased tremendously over the last few years. The cloning of five melanocortin receptors, and the discovery of two endogenous antagonists for these receptors, agouti and agouti-related peptide, have sparked intense interest in the field. Here we give a comprehensive review of the pharmacology, physiology and molecular biology of the melanocortins and their receptors. In particular, we review the roles of the melanocortins in the immune system, behaviour, feeding, the cardiovascular system and melanoma. Moreover, evidence is discussed suggesting that while many of the actions of the melanocortins are mediated via melanocortin receptors, some appear to be mediated via mechanisms distinct from melanocortin receptors.
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Affiliation(s)
- J E Wikberg
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Box 591 BMC, SE751 24, Sweden.
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