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Journal of Developmental Biology Sep 2018In zebrafish (), iridophores are specified from neural crest cells and represent a tractable system for examining mechanisms of cell fate and differentiation. Using this...
In zebrafish (), iridophores are specified from neural crest cells and represent a tractable system for examining mechanisms of cell fate and differentiation. Using this system, we have investigated the role of cAMP protein kinase A (PKA) signaling in pigment cell differentiation. Activation of PKA with the adenylyl cyclase activator forskolin reduces the number of differentiated iridophores in wildtype larvae, with insignificant changes to melanophore number. Inhibition of PKA with H89 significantly increases iridophore number, supporting a specific role for PKA during iridophore development. To determine the effects of altering PKA activity on iridophore and melanophore gene expression, we examined expression of iridophore marker , melanophore marker , and the repressor . Consistent with our cell counts, forskolin significantly decreased expression as detected by in situ hybridization and quantification of cells. Forskolin had the opposite effect on and gene activity, increasing the area of expression. As mutants have extra iridophores as compared to wildtype larvae, we examined the function of during PKA-sensitive iridophore development. Forskolin treatment of mutants did significantly reduce the number of iridophores but to a lesser extent than that observed in treated wildtype larvae. Taken together, our data suggests that PKA inhibits iridophore development in a subset of iridophore precursors, potentially via a -independent pathway.
PubMed: 30261583
DOI: 10.3390/jdb6040023 -
Anatomical Record (Hoboken, N.J. : 2007) Dec 2022The heart begins to form early during vertebrate development and is the first functional organ of the embryo. This study aimed to describe and compare the heart...
The heart begins to form early during vertebrate development and is the first functional organ of the embryo. This study aimed to describe and compare the heart development in three Neotropical anuran species, Physalaemus albonotatus, Elachistocleis bicolor, and Scinax nasicus. Different Gosner Stages (GS) of embryos (GS 18-20) and premetamorphic (GS 21-25), prometamorphic (GS 26-41), and metamorphic (GS 42-46) tadpoles were analyzed using stereoscopic microscopy and Scanning Electronic Microscopy. Heart development was similar in the three analyzed species; however, some heterochronic events were identified between P. albonotatus and S. nasicus compared to E. bicolor. In addition, different patterns of melanophores arrangement were observed. During the embryonic and metamorphic periods, the main morphogenetic events occur: formation of the heart tube, regionalization of the heart compartments, development of spiral valve, onset of heartbeat, looping, and final displacement of the atrium and its complete septation. Both periods are critical for the normal morphogenesis and the correct functioning of the anuran heart. These results are useful to characterize the normal anuran heart morphology and to identify possible abnormalities caused by exposure to environmental contaminants.
Topics: Animals; Organogenesis; Anura; Larva; Morphogenesis; Heart
PubMed: 35412699
DOI: 10.1002/ar.24933 -
Theranostics 2020Prohibitin (PHB, also known as PHB1 or BAP32), is a highly conserved 31kDa protein that expressed in many cellular compartments, such as mitochondria, nucleus, cytosol,...
Prohibitin (PHB, also known as PHB1 or BAP32), is a highly conserved 31kDa protein that expressed in many cellular compartments, such as mitochondria, nucleus, cytosol, and plasma membrane, and plays roles in regulating the transcription of genes, apoptosis, and mitochondrial biogenesis. There is a report that Prohibitin expression is required for the stimulation of pigmentation by melanogenin. However, no studies have been published on the function of PHB in melanocytes, especially in melanosome transport. : Immunofluorescence was performed to confirm the localization of PHB. RNA transfections, Co-immunoprecipitation, western blotting and proximity ligation assay were performed to find binding state between proteins and demonstrate functions of PHB on melanosome transport. : PHB is located in the melanosome and perinuclear aggregation of melanosome is induced when expression of PHB is reduced with no influence on melanin contents. PHB binds directly to Rab27a and Mlph but not Myosin-Va. Rab27a and Mlph bind to specific domains of PHB. Reduced expression of PHB led to the impaired binding affinity between Rab27a and Mlph. : PHB regulates melanosome transport by linking to Rab27a and Mlph in melanocytes. Targeting and regulating PHB not only manages pigmentation in melanocytes, but also controls hyperpigmentation in melanoma.
Topics: Adaptor Proteins, Signal Transducing; Animals; Biological Transport; Cells, Cultured; Melanins; Melanosomes; Mice; Mice, Inbred C57BL; Pigmentation; Prohibitins; Protein Binding; Repressor Proteins; rab27 GTP-Binding Proteins
PubMed: 32226526
DOI: 10.7150/thno.41383 -
Nature Apr 2022Remarkably well-preserved soft tissues in Mesozoic fossils have yielded substantial insights into the evolution of feathers. New evidence of branched feathers in...
Remarkably well-preserved soft tissues in Mesozoic fossils have yielded substantial insights into the evolution of feathers. New evidence of branched feathers in pterosaurs suggests that feathers originated in the avemetatarsalian ancestor of pterosaurs and dinosaurs in the Early Triassic, but the homology of these pterosaur structures with feathers is controversial. Reports of pterosaur feathers with homogeneous ovoid melanosome geometries suggest that they exhibited limited variation in colour, supporting hypotheses that early feathers functioned primarily in thermoregulation. Here we report the presence of diverse melanosome geometries in the skin and simple and branched feathers of a tapejarid pterosaur from the Early Cretaceous found in Brazil. The melanosomes form distinct populations in different feather types and the skin, a feature previously known only in theropod dinosaurs, including birds. These tissue-specific melanosome geometries in pterosaurs indicate that manipulation of feather colour-and thus functions of feathers in visual communication-has deep evolutionary origins. These features show that genetic regulation of melanosome chemistry and shape was active early in feather evolution.
Topics: Animals; Biological Evolution; Dinosaurs; Feathers; Fossils; Melanosomes; Pigmentation
PubMed: 35444275
DOI: 10.1038/s41586-022-04622-3 -
PloS One 2017Potassium channel tetramerization domain containing 15 (Kctd15) was previously found to have a role in early neural crest (NC) patterning, specifically delimiting the...
Potassium channel tetramerization domain containing 15 (Kctd15) was previously found to have a role in early neural crest (NC) patterning, specifically delimiting the region where NC markers are expressed via repression of transcription factor AP-2a and inhibition of Wnt signaling. We used transcription activator-like effector nucleases (TALENs) to generate null mutations in zebrafish kctd15a and kctd15b paralogs to study the in vivo role of Kctd15. We found that while deletions producing frame-shift mutations in each paralog showed no apparent phenotype, kctd15a/b double mutant zebrafish are smaller in size and show several phenotypes including some affecting the NC, such as expansion of the early NC domain, increased pigmentation, and craniofacial defects. Both melanophore and xanthophore pigment cell numbers and early markers are up-regulated in the double mutants. While we find no embryonic craniofacial defects, adult mutants have a deformed maxillary segment and missing barbels. By confocal imaging of mutant larval brains we found that the torus lateralis (TLa), a region implicated in gustatory networks in other fish, is absent. Ablation of this brain tissue in wild type larvae mimics some aspects of the mutant growth phenotype. Thus kctd15 mutants show deficits in the development of both neural crest derivatives, and specific regions within the central nervous system, leading to a strong reduction in normal growth rates.
Topics: Animals; Frameshift Mutation; Potassium Channels, Voltage-Gated; Zebrafish; Zebrafish Proteins
PubMed: 29216270
DOI: 10.1371/journal.pone.0189162 -
Genetics in Medicine : Official Journal... Mar 2021Albinism is a clinically and genetically heterogeneous condition. Despite analysis of the 20 known genes, ~30% patients remain unsolved. We aimed to identify new genes...
PURPOSE
Albinism is a clinically and genetically heterogeneous condition. Despite analysis of the 20 known genes, ~30% patients remain unsolved. We aimed to identify new genes involved in albinism.
METHODS
We sequenced a panel of genes with known or predicted involvement in melanogenesis in 230 unsolved albinism patients.
RESULTS
We identified variants in the Dopachrome tautomerase (DCT) gene in two patients. One was compound heterozygous for a 14-bp deletion in exon 9 and c.118T>A p.(Cys40Ser). The second was homozygous for c.183C>G p.(Cys61Trp). Both patients had mild hair and skin hypopigmentation, and classical ocular features. CRISPR-Cas9 was used in C57BL/6J mice to create mutations identical to the missense variants carried by the patients, along with one loss-of-function indel. When bred to homozygosity the three mutations revealed hypopigmentation of the coat, milder for Cys40Ser compared with Cys61Trp or the frameshift mutation. Histological analysis identified significant hypopigmentation of the retinal pigmented epithelium (RPE) indicating that defective RPE melanogenesis could be associated with eye and vision defects. DCT loss of function in zebrafish embryos elicited hypopigmentation both in melanophores and RPE cells.
CONCLUSION
DCT is the gene for a new type of oculocutaneous albinism that we propose to name OCA8.
Topics: Albinism, Oculocutaneous; Animals; Humans; Intramolecular Oxidoreductases; Mice; Mice, Inbred C57BL; Mutation; Zebrafish
PubMed: 33100333
DOI: 10.1038/s41436-020-00997-8 -
Biomolecules Jul 2019Melanosomes undergo a complex maturation process and migrate into keratinocytes. Melanophilin (Mlph), a protein complex involving myosin Va (MyoVa) and Rab27a, enables...
Melanosomes undergo a complex maturation process and migrate into keratinocytes. Melanophilin (Mlph), a protein complex involving myosin Va (MyoVa) and Rab27a, enables the movement of melanosomes in melanocytes. In this study, we found six miRNAs targeting in mouse using two programs (http://targetscan.org and DianaTools). When melan-a melanocytes were treated with six synthesized microRNAs, miR-342-5p, miR-1839-5p, and miR-3082-5p inhibited melanosome transport and induced melanosome aggregation around the nucleus. The other microRNAs, miR-5110, miR-3090-3p, and miR-186-5p, did not inhibit melanosome transport. Further, miR-342-5p, miR-1839-5p, and miR-3082-5p decreased expression. The effect of miR-342-5p was the strongest among the six synthesized miRNAs. It inhibited melanosome transport in melan-a melanocytes and reduced expression in mRNA and protein levels in a dose-dependent manner; however, it did not affect Rab27a and MyoVa expressions, which are associated with melanosome transport. To examine miR-342-5p specificity, we performed luciferase assays in a mouse melanocyte-transfected reporter vector including at the 3'-UTR (untranslated region). When treated with miR-342-5p, luciferase activity that had been reduced by approximately 50% was restored after inhibitor treatment. Therefore, we identified a novel miRNA affecting and melanosome transport, and these results can be used for understanding Mlph expression and skin pigmentation regulation.
Topics: Adaptor Proteins, Signal Transducing; Animals; Biological Transport; Cells, Cultured; Melanosomes; Mice; Mice, Inbred C57BL; MicroRNAs
PubMed: 31288473
DOI: 10.3390/biom9070265 -
Traffic (Copenhagen, Denmark) Jul 2016VARP (VPS9-ankyrin-repeat protein, also known as ANKRD27) was originally identified as an N-terminal VPS9 (vacuolar protein sorting 9)-domain-containing protein that... (Review)
Review
VARP (VPS9-ankyrin-repeat protein, also known as ANKRD27) was originally identified as an N-terminal VPS9 (vacuolar protein sorting 9)-domain-containing protein that possesses guanine nucleotide exchange factor (GEF) activity toward small GTPase Rab21 and contains two ankyrin repeat (ANKR) domains in its central region. A number of VARP-interacting molecules have been identified during the past five years, and considerable attention is now being directed to the multiple roles of VARP in endosomal trafficking. More specifically, VARP is now known to interact with three different types of key membrane trafficking regulators, i.e. small GTPase Rabs (Rab32, Rab38 and Rab40C), the retromer complex (a sorting nexin dimer, VPS26, VPS29 and VPS35) and R-SNARE VAMP7. By binding to several of these molecules, VARP regulates endosomal trafficking, which underlies a variety of cellular events, including melanogenic enzyme trafficking to melanosomes, dendrite outgrowth of melanocytes, neurite outgrowth and retromer-mediated endosome-to-plasma membrane sorting of transmembrane proteins.
Topics: Animals; Dendrites; Endosomes; Guanine Nucleotide Exchange Factors; Humans; Intracellular Membranes; Ligands; Melanocytes; Melanosomes; Membrane Proteins; Neuronal Outgrowth; Organ Specificity; Protein Binding; Protein Transport; R-SNARE Proteins; rab GTP-Binding Proteins
PubMed: 27103185
DOI: 10.1111/tra.12406 -
BioEssays : News and Reviews in... Jan 2024Modeling metastasis in animal systems has been an important focus for developing cancer therapeutics. Xenopus laevis is a well-established model, known for its use in... (Review)
Review
Modeling metastasis in animal systems has been an important focus for developing cancer therapeutics. Xenopus laevis is a well-established model, known for its use in identifying genetic mechanisms underlying diseases and disorders in humans. Prior literature has suggested that the drug, ivermectin, can be used in Xenopus to induce melanocytes to convert into a metastatic melanoma-like state, and thus could be ideal for testing possible melanoma therapies in vivo. However, there are notable inconsistencies between ivermectin studies in Xenopus and the application of ivermectin in mammalian systems, that are relevant to cancer and melanoma research. In this review, we examine the ivermectin-induced phenotypes in Xenopus, and we explore the current uses of ivermectin in human research. We conclude that while ivermectin may be a useful drug for many biomedical purposes, it is not ideal to induce a metastatic melanocyte phenotype in Xenopus for testing the effects of potential melanoma therapeutics.
Topics: Animals; Humans; Melanoma; Xenopus laevis; Ivermectin; Melanocytes; Mammals
PubMed: 37985957
DOI: 10.1002/bies.202300143 -
The Journal of Biological Chemistry Nov 2022Melanosomes are melanin-containing organelles in melanocytes, and they are responsible for skin and hair pigmentation in mammals. The intracellular distribution of...
Melanosomes are melanin-containing organelles in melanocytes, and they are responsible for skin and hair pigmentation in mammals. The intracellular distribution of melanosomes is mainly determined by the balance between their anterograde transport on actin filaments and retrograde transport on microtubules. Although we have shown previously that melanoregulin and Rab36 serve as cargo receptors on melanosomes for retrograde transport, their knockdown does not completely inhibit retrograde melanosome transport, suggesting the existence of an additional cargo receptor(s) in melanocytes. In this study, we investigated the possible involvement of an atypical large Rab, Rab44, which also contains EF-hand domains and a coiled-coil domain, in retrograde melanosome transport in mouse melanocytes (Rab27A-deficient melan-ash cells). Our results showed that Rab44 localizes on mature melanosomes through lipidation of its C-terminal Rab-like GTPase domain, and that its knockdown results in suppression of retrograde melanosome transport. In addition, our biochemical analysis indicated that Rab44 interacts with the dynein-dynactin motor complex via its coiled-coil domain-containing middle region. Since simultaneous depletion of Rab44, melanoregulin, and Rab36 resulted in almost complete inhibition of retrograde melanosome transport, we propose that Rab44 is the third cargo receptor. We also showed that the N-terminal region of Rab44, which contains EF-hand domains, is required for both retrograde melanosome transport and its Ca-modulated activities. Our findings indicated that Rab44 is a third melanosomal cargo receptor, and that, unlike other cargo receptors previously described, its transport function is regulated by Ca.
Topics: Mice; Animals; Melanosomes; rab GTP-Binding Proteins; Melanocytes; Biological Transport; Microtubules; Dynactin Complex; Mammals; Adaptor Proteins, Vesicular Transport
PubMed: 36126775
DOI: 10.1016/j.jbc.2022.102508