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Fukuzawa T. Periodic albinism of a widely used albino mutant of Xenopus laevis caused by deletion of two exons in the Hermansky-Pudlak syndrome type 4 gene. Genes Cells 2020; 26:31-39. [PMID: 33147376 PMCID: PMC7839477 DOI: 10.1111/gtc.12818] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 10/30/2020] [Accepted: 10/30/2020] [Indexed: 01/10/2023]
Abstract
The periodic albino mutant of Xenopus laevis is a recessive mutant, in which reduced amounts of melanin appear in the retinal pigment epithelium (RPE) and in melanophores at the late embryonic stage, after which both RPE and melanophores gradually depigment. Three types of pigment cells (melanophores, iridophores and xanthophores) have been reported to be affected in this albino. However, the causative gene of the periodic albinism remains unknown. Hermansky–Pudlak syndrome (HPS) is an autosomal recessive disorder that affects humans and mice, which is caused by defective biogenesis of lysosome‐related organelles (LROs). Two subgenomes (L and S) are present in the allotetraploid frog X. laevis. Comparison of genes between the chromosomes 1L and 1S revealed that the HPS type 4 (hps4) gene was present only in chromosome 1L. In the albino mutant, a 1.9 kb genomic deletion in the hps4.L gene including exons 7 and 8 caused a premature stop codon to create a truncated Hps4 protein. Injection of wild‐type hps4.L mRNA into mutant embryos rescued the albino phenotype. These findings indicate that hps4 is a causative gene for the periodic albinism in X. laevis. The phenotype of this mutant should be reassessed from the perspective of LRO biogenesis.
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Ullate-Agote A, Burgelin I, Debry A, Langrez C, Montange F, Peraldi R, Daraspe J, Kaessmann H, Milinkovitch MC, Tzika AC. Genome mapping of a LYST mutation in corn snakes indicates that vertebrate chromatophore vesicles are lysosome-related organelles. Proc Natl Acad Sci U S A 2020; 117:26307-26317. [PMID: 33020272 PMCID: PMC7584913 DOI: 10.1073/pnas.2003724117] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Reptiles exhibit a spectacular diversity of skin colors and patterns brought about by the interactions among three chromatophore types: black melanophores with melanin-packed melanosomes, red and yellow xanthophores with pteridine- and/or carotenoid-containing vesicles, and iridophores filled with light-reflecting platelets generating structural colors. Whereas the melanosome, the only color-producing endosome in mammals and birds, has been documented as a lysosome-related organelle, the maturation paths of xanthosomes and iridosomes are unknown. Here, we first use 10x Genomics linked-reads and optical mapping to assemble and annotate a nearly chromosome-quality genome of the corn snake Pantherophis guttatus The assembly is 1.71 Gb long, with an N50 of 16.8 Mb and L50 of 24. Second, we perform mapping-by-sequencing analyses and identify a 3.9-Mb genomic interval where the lavender variant resides. The lavender color morph in corn snakes is characterized by gray, rather than red, blotches on a pink, instead of orange, background. Third, our sequencing analyses reveal a single nucleotide polymorphism introducing a premature stop codon in the lysosomal trafficking regulator gene (LYST) that shortens the corresponding protein by 603 amino acids and removes evolutionary-conserved domains. Fourth, we use light and transmission electron microscopy comparative analyses of wild type versus lavender corn snakes and show that the color-producing endosomes of all chromatophores are substantially affected in the LYST mutant. Our work provides evidence characterizing xanthosomes in xanthophores and iridosomes in iridophores as lysosome-related organelles.
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Affiliation(s)
- Asier Ullate-Agote
- Laboratory of Artificial & Natural Evolution (LANE), Department of Genetics & Evolution, University of Geneva, CH-1211 Geneva, Switzerland
- SIB Swiss Institute of Bioinformatics, Switzerland
- Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva, Switzerland
| | - Ingrid Burgelin
- Laboratory of Artificial & Natural Evolution (LANE), Department of Genetics & Evolution, University of Geneva, CH-1211 Geneva, Switzerland
| | - Adrien Debry
- Laboratory of Artificial & Natural Evolution (LANE), Department of Genetics & Evolution, University of Geneva, CH-1211 Geneva, Switzerland
| | - Carine Langrez
- Laboratory of Artificial & Natural Evolution (LANE), Department of Genetics & Evolution, University of Geneva, CH-1211 Geneva, Switzerland
| | - Florent Montange
- Laboratory of Artificial & Natural Evolution (LANE), Department of Genetics & Evolution, University of Geneva, CH-1211 Geneva, Switzerland
| | - Rodrigue Peraldi
- Laboratory of Artificial & Natural Evolution (LANE), Department of Genetics & Evolution, University of Geneva, CH-1211 Geneva, Switzerland
| | - Jean Daraspe
- Faculté de Biologie et de Médecine, Electron Microscopy Facility, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Henrik Kaessmann
- DKFZ-ZMBH Alliance, Center for Molecular Biology of Heidelberg University (ZMBH), D-69120 Heidelberg, Germany
| | - Michel C Milinkovitch
- Laboratory of Artificial & Natural Evolution (LANE), Department of Genetics & Evolution, University of Geneva, CH-1211 Geneva, Switzerland
- SIB Swiss Institute of Bioinformatics, Switzerland
- Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva, Switzerland
| | - Athanasia C Tzika
- Laboratory of Artificial & Natural Evolution (LANE), Department of Genetics & Evolution, University of Geneva, CH-1211 Geneva, Switzerland;
- SIB Swiss Institute of Bioinformatics, Switzerland
- Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva, Switzerland
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Fukuzawa T, Kikuchi Y. Unusual light-reflecting pigment cells appear in the Xenopus neural tube culture system in the presence of guanosine. Tissue Cell 2018; 54:55-58. [PMID: 30309510 DOI: 10.1016/j.tice.2018.08.003] [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: 05/08/2018] [Revised: 07/19/2018] [Accepted: 08/08/2018] [Indexed: 11/17/2022]
Abstract
Isolation and culture of Xenopus laevis neural tubes resulted in differentiation of melanophores and iridophores from neural crest cells; the differentiated melanophores and iridophores were then maintained in culture for more than 6 months. Guanosine has been reported to promote reflecting platelet formation in melanin-producing pigment cells; however, the process of pigment organellogenesis is still unclear. In the present study, unusual light-reflecting pigment cells were observed upon addition of guanosine to the neural tube culture system, which contained melanosomes specific to melanophores, and reflecting platelets specific to iridophores. Ultrastructural studies suggested that irregularly shaped reflecting platelets were formed from stage II melanosomes (the early stage of melanosome formation) in these unusual pigment cells.
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Affiliation(s)
- Toshihiko Fukuzawa
- Department of Biology, Keio University, Hiyoshi 4-1-1, Kohoku-ku, Yokohama 223-8521, Japan.
| | - Yutaka Kikuchi
- Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima, 739-8526 Japan.
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Fukuzawa T. A wide variety of Mitf transcript variants are expressed in the Xenopus laevis periodic albino mutant. Genes Cells 2018; 23:638-648. [PMID: 29920861 DOI: 10.1111/gtc.12606] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 05/10/2018] [Accepted: 05/18/2018] [Indexed: 11/29/2022]
Abstract
The periodic albino mutant of Xenopus laevis has been used to study the development of pigment cells because both the retinal pigment epithelium (RPE) and melanophores are affected. In this mutant, "white pigment cells" containing both melanophore-specific and iridophore-specific pigment organelles appear. The present experiments were designed to investigate the structural organization and expression of microphthalmia-associated transcription factor (Mitf) in the mutant since Mitf is known to regulate the development of melanocytes and RPE. The exon structures of X. laevis mitf genes (mitf.L and mitf.S) were defined using newly obtained Mitf transcripts and X. laevis genomic data. Compared to mouse mitf, exons 3 and 6a were absent in X. laevis mitf. The four exons between exons 4 and 6b in X. laevis mitf were named 5α, 5β, 5γ, and 5δ. Exons 5α and 5δ were specific to X. laevis mitf, whereas the continuous exons 5β/γ were identical to exon 5 of mouse mitf. A wide variety of A-Mitf and M-Mitf transcript variants lacking one or more exons were found in X. laevis; however, different types of Mitf transcripts were expressed in the mutant. In addition, white pigment cells and melanophores expressed both the mitf and dopachrome tautomerase (dct) genes.
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Sun W, Jiao C, Xiao Y, Wang L, Yu C, Liu J, Yu Y, Wang L. Salt-Dependent Aggregation and Assembly of E coli-Expressed Ferritin. Dose Response 2016; 14:1559325816632102. [PMID: 26977139 PMCID: PMC4773902 DOI: 10.1177/1559325816632102] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Ferritin, with the primary function of iron storage, is a nearly ubiquitous protein found in most living organisms. Our recent investigations suggest that ferritin can assemble nanoparticles. So we use ferritin as a novel type of delivery vehicle for recombinant epitope vaccines. And, we found that ferritin form nonnative aggregates depended sensitively on NaCl concentrations. Here, we report that ferritin is an ion-sensitive protein and has the attribute of salt-dependent aggregation. Our results indicate that recombinant ferritin can be released as a soluble form from Escherichia coli at low NaCl concentrations (≤50 mmol/L). Moreover, this result affords us to confirm a proper self-assembling solution for soluble ferritin or other ferritin-based fusion proteins to assemble nanoparticles.
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Affiliation(s)
- Wei Sun
- Department of Molecular Biology, College of Basic Medicine, Jilin University, Changchun, China
| | - Chengfeng Jiao
- Department of Molecular Biology, College of Basic Medicine, Jilin University, Changchun, China
| | - Yue Xiao
- Department of Molecular Biology, College of Basic Medicine, Jilin University, Changchun, China
| | - Luowei Wang
- Department of Molecular Biology, College of Basic Medicine, Jilin University, Changchun, China
| | - Cheng Yu
- Department of Molecular Biology, College of Basic Medicine, Jilin University, Changchun, China
| | - Jialin Liu
- Department of Molecular Biology, College of Basic Medicine, Jilin University, Changchun, China
| | - Yongli Yu
- Department of Immunology, College of Basic Medicine, Jilin University, Changchun, China
| | - Liying Wang
- Department of Molecular Biology, College of Basic Medicine, Jilin University, Changchun, China
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Ali SA, Naaz I. Understanding the ultrastructural aspects of berberine-induced skin-darkening activity in the toad, Bufo melanostictus, melanophores. J Microsc Ultrastruct 2015; 3:210-219. [PMID: 30023201 PMCID: PMC6014273 DOI: 10.1016/j.jmau.2015.07.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 07/07/2015] [Accepted: 07/25/2015] [Indexed: 11/07/2022] Open
Abstract
Berberine is an active compound of Berberis vulgaris (Daruhaldi) with known multiple pharmacological activities, including antimicrobial, antiviral, anti-inflammatory, cholesterol-lowering, and anticancer effects. The present work aimed to study the ultrastructural effects of berberine to determine its skin-darkening potential using Bufo melanostictus melanophores, which has not been done to date. Light and electron microscopic analysis of isolated dorsal skin melanophores of B. melanostictus has been done after treatment with various concentrations of berberine, along with specific antagonists and agonists of β-adrenoceptors in order to explore the mechanism of action of berberine-induced skin darkening. The results showed that the number of melanophores with melanin-loaded dendrites increased in the subepidermal layer significantly in berberine-treated skin pieces in a dose-dependent manner leading to skin darkening. Highly electron-dense melanosomes of Stage IV increased considerably due to the enhanced process of melanization. These effects were found to be antagonized by propranolol, and were also found to be highly potentiated by isoprenaline, which is a specific β-adrenoceptor agonist. The findings show that berberine possesses a skin-darkening potential and could be used as a safe melanogenic agent for the treatment of hypopigmentation disorders or vitiligo.
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Affiliation(s)
- Sharique A Ali
- Post Graduate Department of Biotechnology, Saifia Science College, Bhopal, MP 462001, India
| | - Ishrat Naaz
- Post Graduate Department of Biotechnology, Saifia Science College, Bhopal, MP 462001, India
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