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The Journal of Investigative Dermatology Feb 2020Pigmentation of the skin and hair represents the result of melanin biosynthesis within melanosomes of epidermal melanocytes, followed by the transfer of mature melanin... (Review)
Review
Pigmentation of the skin and hair represents the result of melanin biosynthesis within melanosomes of epidermal melanocytes, followed by the transfer of mature melanin granules to adjacent keratinocytes within the basal layer of the epidermis. Natural variation in these processes produces the diversity of skin and hair color among human populations, and defects in these processes lead to diseases such as oculocutaneous albinism. While genetic regulators of pigmentation have been well studied in human and animal models, we are still learning much about the cell biological features that regulate melanogenesis, melanosome maturation, and melanosome motility in melanocytes, and have barely scratched the surface in our understanding of melanin transfer from melanocytes to keratinocytes. Herein, we describe cultured cell model systems and common assays that have been used by investigators to dissect these features and that will hopefully lead to additional advances in the future.
Topics: Animals; Cell Culture Techniques; Coculture Techniques; Humans; Image Processing, Computer-Assisted; Intravital Microscopy; Keratinocytes; Melanins; Melanosomes; Microscopy, Electron, Transmission; Microscopy, Fluorescence; Pigmentation Disorders; Research Design; Skin Pigmentation; Spectrophotometry
PubMed: 31980058
DOI: 10.1016/j.jid.2019.12.002 -
MSphere Feb 2023Melanin is a complex pigment that is found in various fungal species and is associated with a multitude of protective functions against environmental stresses. In...
Melanin is a complex pigment that is found in various fungal species and is associated with a multitude of protective functions against environmental stresses. In Cryptococcus neoformans, melanin is synthesized from exogenous substrate and deposited in the cell wall. Although melanin is often cited as a protector against mechanical stress, there is a paucity of direct experimental data supporting this claim. To probe whether melanin enhances cellular strength, we used ultrasonic cavitation and French cell press pressure to stress cryptococcal cells and then measured changes in cellular morphology and fragmentation for melanized and nonmelanized C. neoformans cells. Melanized yeast cells exhibited lower rates of fragmentation and greater cell areas than did nonmelanized yeast cells after sonication or French press passage. When subjected to French press passage, both melanized and nonmelanized cells exhibited responses that were dependent on their culture age. Our results indicate that melanization protects against some of the morphological changes, such as fragmentation and cellular shrinkage, that are initiated by mechanical energy derived from either sonic cavitation or French press passage, thus supporting the notion that this pigment provides mechanical strength for fungal cell walls. Melanin was shown in prior microbiological experiments to be associated with protection against environmental stressors, and it has often been cited as being associated with mechanical stress protection. However, there is a lack of direct experimentation to confirm this claim. We examined the responses of melanized and nonmelanized C. neoformans cells to sonication and French press passage, and we report differences in outcomes depending not only on melanization status but also on culture age. Such findings have important implications for the design and interpretation of laboratory experiments involving C. neoformans. In addition, the elucidation of some of the mechanical properties of melanin promotes further research into fungal melanin applications in health care and industry.
Topics: Cryptococcus neoformans; Melanins; Saccharomyces cerevisiae; Stress, Mechanical; Cryptococcosis
PubMed: 36602315
DOI: 10.1128/msphere.00591-22 -
International Journal of Molecular... Aug 2019The generic term "melanin" describes a black pigment of biological origin, although some melanins can be brown or even yellow. The pigment is characterized as a... (Review)
Review
The generic term "melanin" describes a black pigment of biological origin, although some melanins can be brown or even yellow. The pigment is characterized as a heterogenic polymer of phenolic or indolic nature, and the classification of eu-, pheo- and allo- melanin is broadly accepted. This classification is based on the chemical composition of the monomer subunit structure of the pigment. Due to the high heterogeneity of melanins, their analytical characterization can be a challenging task. In the present work, we synthesized the current information about the analytical methods which can be applied in melanin analysis workflow, from extraction and purification to high-throughput methods, such as matrix-assisted laser desorption/ionization mass-spectrometry or pyrolysis gas chromatography. Our thorough comparative evaluation of analytical data published so far on melanin analysis has proven to be a difficult task in terms of finding equivalent results, even when the same matrix was used. Moreover, we emphasize the importance of prior knowledge of melanin types and properties in order to select a valid experimental design using analytical methods that are able to deliver reliable results and draw consistent conclusions.
Topics: Animals; Chemical Fractionation; Chemical Phenomena; Humans; Melanins; Molecular Structure; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Spectrum Analysis
PubMed: 31412656
DOI: 10.3390/ijms20163943 -
Toxins Jun 2022Melanin has been reported to have potential applications in industries such as cosmetics and food due to its anti-UV and antioxidative qualities. However, the...
Melanin has been reported to have potential applications in industries such as cosmetics and food due to its anti-UV and antioxidative qualities. However, the corresponding data on its safety evaluation or biological consequences are fairly limited; such data are critical given its widespread use. The effect of different concentrations (1, 2, 3, and 4%) of melanin on growth status (larvae length and weight, cocoon weight, and morphology), the microstructure of the various tissues (fat body, silk gland, and midgut), and silk properties was studied by using the silkworm () as the model organism. The weight and length of silkworm larvae fed with melanin were lower than the control, indicating that melanin appears to have a negative effect on the growth status of silkworms; however, the histophysiology analysis indicates that the cell morphologies are not changed, the XRD and FTIR spectra indicate that the secondary and crystalline structures of silks are also well preserved, and the thermogravimetric analysis and tensile test indicate that the thermal stability and mechanical properties are well maintained and even improved to some extent. Generally, it indicates that melanin has a certain inhibitory effect on the growth of silkworm larva but causes no harm to the cell microstructures or silk properties; this demonstrates that the safety of melanin as a food addictive should be considered seriously. The increase of thermal stability and mechanical properties shows that melanin may be a good chemical modifier in textile industries.
Topics: Animals; Bombyx; Digestive System; Larva; Melanins; Silk
PubMed: 35878159
DOI: 10.3390/toxins14070421 -
Skin Research and Technology : Official... May 2023To characterize the effects of miRNA-27a-3p on the biological properties of human epidermal melanocytes (MCs).
OBJECTIVE
To characterize the effects of miRNA-27a-3p on the biological properties of human epidermal melanocytes (MCs).
METHODS
MCs were obtained from human foreskins and transfected with miRNA-27a-3p mimic (induces the overexpression of miRNA-27a-3p), mimic-NC (the negative control group), miRNA-27a-3p inhibitor, or inhibitor-NC. After transfection, the proliferation of MCs in each group was evaluated by cell counting kit-8 (CCK-8) at 1, 3, 5, and 7 days. Twenty-four hours later, the MCs were transferred onto a living cell imaging platform and cultured for another 12 h to detect their trajectories and velocities. On days 3, 4, and 5 after transfection, the expression of melanogenesis-related mRNAs, protein levels, and melanin contents were measured using reverse transcription-polymerase chain reaction (RT-PCR), Western blotting, and NaOH solubilization, respectively.
RESULTS
The RT-PCR results showed that miRNA-27a-3p was successfully transfected into MCs. The proliferation of MCs was restrained by miRNA-27a-3p. There were no significant differences in the movement trajectories of MCs in the four transfected groups, but the cell movement velocity in the mimic group was slightly lower; that is, the overexpression of miRNA-27a-3p inhibited the speed of MCs. The expression levels of melanogenesis-related mRNAs and proteins were decreased in the mimic group and were increased in the inhibitor group. Melanin content in the mimic group was lower than that in the other three groups.
CONCLUSIONS
Overexpression of miRNA-27a-3p inhibits the expression of melanogenesis-related mRNAs and proteins, reduces the melanin content of human epidermal MCs, and slightly impacts their movement speed.
Topics: Humans; MicroRNAs; Melanins; Melanocytes; Epidermis; Cells, Cultured; RNA, Messenger; Cell Proliferation
PubMed: 37231929
DOI: 10.1111/srt.13345 -
Frontiers in Neuroendocrinology Jul 2023Hypothalamic melanin-concentrating hormone (MCH) neurons participate in many fundamental neuroendocrine processes. While some of their effects can be attributed to MCH... (Review)
Review
Hypothalamic melanin-concentrating hormone (MCH) neurons participate in many fundamental neuroendocrine processes. While some of their effects can be attributed to MCH itself, others appear to depend on co-released neurotransmitters. Historically, the subject of fast neurotransmitter co-release from MCH neurons has been contentious, with data to support MCH neurons releasing GABA, glutamate, both, and neither. Rather than assuming a position in that debate, this review considers the evidence for all sides and presents an alternative explanation: neurochemical identity, including classical neurotransmitter content, is subject to change. With an emphasis on the variability of experimental details, we posit that MCH neurons may release GABA and/or glutamate at different points according to environmental and contextual factors. Through the lens of the MCH system, we offer evidence that the field of neuroendocrinology would benefit from a more nuanced and dynamic interpretation of neurotransmitter identity.
Topics: Hypothalamic Hormones; Pituitary Hormones; Neurons; Melanins; Hypothalamus; Glutamic Acid; Neurotransmitter Agents; gamma-Aminobutyric Acid
PubMed: 37149229
DOI: 10.1016/j.yfrne.2023.101069 -
Brazilian Journal of Microbiology :... Mar 2021Melanin is a Sporothrix virulence factor that can inhibit the innate immune functions of macrophages such as phagocytosis and killing. However, no data on melanin's...
Melanin is a Sporothrix virulence factor that can inhibit the innate immune functions of macrophages such as phagocytosis and killing. However, no data on melanin's influence on antigen presentation by macrophages are available. In this study, we used conidia, yeasts, and melanin ghosts (MGs) from a black Sporothrix globosa strain (MEL+) and its ultraviolet-induced albino mutant (MEL-), to study the influence of melanin on expression of molecules involved in antigen presentation by mouse macrophages (MHC class II, CD80, CD86), as well as on levels of transcription factors regulating their expression (CIITA and promoters I, III, and IV). A murine infection model was used to assess the virulence of both strains and differences in expression of MHC class II and CD80/86 in vivo. MHC class II, CD86 CIITA, and PIV expressions were lower in macrophages infected with MEL+ than in macrophages infected with MEL- conidia, while CD80 expression was similar. No statistical difference in gene expression was observed between macrophages infected by MEL+ and MEL- yeasts. Infection by MGs alone had no clear effect on expression of antigen presentation-associated molecules. Mice infected with MEL+ S. globosa had significantly higher fungal burdens in the lung, liver, spleen, kidney, and testicle compared with mice infected with MEL- S. globosa 21 days post-infection. MHC class II expression changes in the animal study were similar to those observed in the in vitro experiment. Our results indicate that S. globosa melanin can inhibit expression of antigen presentation-associated molecules during both the early and late stages of infection, representing a new mechanism to evade host immunity and to enhance dissemination. Further investigations of melanin's impact on adaptive immunity will be helpful in understanding this fungal virulence factor.
Topics: Animals; Antigen Presentation; Histocompatibility Antigens Class II; Host-Pathogen Interactions; Humans; Liver; Lung; Macrophages, Peritoneal; Male; Melanins; Mice; Mice, Inbred BALB C; Sporothrix; Sporotrichosis
PubMed: 32772310
DOI: 10.1007/s42770-020-00345-7 -
Molecules (Basel, Switzerland) May 2021Velutin, one of the flavones contained in natural plants, has various beneficial activities, such as skin whitening, as well as anti-inflammatory, anti-allergic,...
Velutin, one of the flavones contained in natural plants, has various beneficial activities, such as skin whitening, as well as anti-inflammatory, anti-allergic, antioxidant, and antimicrobial activities. However, the relationship between the structure of velutin and its anti-melanogenesis activity is not yet investigated. In this study, we obtained 12 velutin derivatives substituted at C5, C7, C3', and C4' of the flavone backbone with hydrogen, hydroxyl, and methoxy functionalities by chemical synthesis, to perform SAR analysis of velutin structural analogues. The SAR study revealed that the substitution of functional groups at C5, C7, C3', and C4' of the flavone backbone affects biological activities related to melanin synthesis. The coexistence of hydroxyl and methoxy at the C5 and C7 position is essential for inhibiting tyrosinase activity. However, 1,2-diol compounds substituted at C3' and C4' of flavone backbone induce apoptosis of melanoma cells. Further, substitution at C3' and C4' with methoxy or hydrogen is essential for inhibiting melanogenesis. Thus, this study would be helpful for the development of natural-derived functional materials to regulate melanin synthesis.
Topics: Animals; Cell Line, Tumor; Flavones; Melanins; Mice; Molecular Docking Simulation; Proton Magnetic Resonance Spectroscopy; Structure-Activity Relationship
PubMed: 34069624
DOI: 10.3390/molecules26103033 -
Pigment Cell & Melanoma Research Jul 2021Melanins are widely distributed in animals and plants; in vertebrates, most melanins are present on the body surface. The diversity of pigmentation in vertebrates is... (Review)
Review
Melanins are widely distributed in animals and plants; in vertebrates, most melanins are present on the body surface. The diversity of pigmentation in vertebrates is mainly attributed to the quantity and ratio of eumelanin and pheomelanin synthesis. Most natural melanin pigments in animals consist of both eumelanin and pheomelanin in varying ratios, and thus, their combined synthesis is called "mixed melanogenesis." Gene expression is an established mechanism for controlling melanin synthesis; however, there are multiple factors that affect melanin synthesis besides gene expression. Due to the differential sensitivity of the eumelanin and pheomelanin synthetic pathways to pH, melanosomal pH likely plays a major role in mixed melanogenesis. Here, we focused on various factors affecting mixed melanogenesis including (1) chemical regulation of melanin synthesis, (2) melanosomal pH regulation during normal melanogenesis and effect on mixed melanogenesis, and (3) mechanisms of melanosomal pH control (proton pumps, channels, transporters, and signaling pathways).
Topics: Animals; Cysteine; Humans; Kinetics; Melanins; Melanosomes; Monophenol Monooxygenase; Skin Pigmentation
PubMed: 33751833
DOI: 10.1111/pcmr.12970 -
International Journal of Molecular... Sep 2017Research on the supramolecular buildup of eumelanin has gained high momentum in the last years. Several new aspects regarding the involved structures and mechanisms have... (Review)
Review
Research on the supramolecular buildup of eumelanin has gained high momentum in the last years. Several new aspects regarding the involved structures and mechanisms have been established, which has led to a better understanding of the entire process. This review intends to provide a clearly laid-out summary of previous and new findings regarding structures, mechanisms, and controllability. With respect to materials applications, the aspect of controllability is of supreme importance. A focus of this review is therefore set on a novel method with high potential for specific synthesis of various, isolated particle morphologies. Finally, open questions and possibilities for their elucidation are discussed.
Topics: Animals; Humans; Melanins; Nanoparticles
PubMed: 28878140
DOI: 10.3390/ijms18091901