Melanocytes Research Articles

Neural crest lineage in the protovertebrate model Ciona.

Neural crest cells are multipotent progenitors that produce defining features of vertebrates such as the 'new head'1. Here we use the tunicate, Ciona, to explore the evolutionary origins of neural crest since this invertebrate chordate is among the closest living relatives of vertebrates2-4. Previous studies identified two potential neural crest cell types in Ciona, sensory pigment cells and bipolar tail neurons5,6. Recent findings suggest that bipolartail neurons are homologous to cranial sensory ganglia rather than derivatives of neural crest7,8. Here we show that the pigment cell lineage also produces neural progenitor cells that form regions of the juvenile nervous system following metamorphosis. Neural progenitors are also a major derivative of neural crest in vertebrates, suggesting that the last common ancestor of tunicates and vertebrates contained a multipotent progenitor population at the neural plate border. It would therefore appear that a key property of neural crest, multipotentiality, preceded the emergence of vertebrates.

Characterization of cellular and molecular immune components of the painted white sea urchin Lytechinus pictus in response to bacterial infection.

Sea urchins are basal deuterostomes that share key molecular components of innate immunity with vertebrates. They are a powerful model for the study of innate immune system evolution and function, especially during early development. Here we characterize the morphology and associated molecular markers of larval immune cell types in a newly developed model sea urchin, Lytechinus pictus. We then challenge larvae through infection with an established pathogenic Vibrio and characterize phenotypic and molecular responses. We contrast these to the previously described immune responses of the purple sea urchin Strongylocentrotus purpuratus. The results revealed shared cellular morphologies and homologs of known pigment cell immunocyte markers (PKS, srcr142) but a striking absence of subsets of perforin-like macpf genes in blastocoelar cell immunocytes. We also identified novel patterning of cells expressing a scavenger receptor cysteine rich (SRCR) gene in the coelomic pouches of the larva (the embryonic stem cell niche). The SRCR signal becomes further enriched in both pouches in response to bacterial infection. Collectively, these results provide a foundation for the study of immune responses in L. pictus. The characterization of the larval immune system of this rapidly developing and genetically enabled sea urchin species will facilitate more sophisticated studies of innate immunity and the crosstalk between the immune system and development.

Stromal Expression Profiling Reveals Immune-Driven Adaption to Malignancy in Canine Melanoma Subtypes.

Canine mucosal melanoma (CMM) is the most common oral malignancy in dogs and is significantly more aggressive than its cutaneous counterpart (CCM), yet the reasons for this disparity remain unclear. Cancer-associated stroma (CAS) plays a crucial role in tumour progression, but a detailed understanding of CAS in canine melanoma is missing. To assess stromal reprogramming, we analysed CAS from 21 CMM, 14 CCM and normal stroma from 10 skin and 9 oral mucosa samples by laser-capture microdissection followed by RNA sequencing. Results were assessed in relation to subtypes, prognostic factors including mitotic count (MC), ulceration, necrosis, pigmentation and immune cell infiltration (CD3, CD20 and CD68), scored using immunohistochemistry and RNA in situ hybridisation. Stromal reprogramming was evident in both subtypes but significantly more pronounced in CMM. Immune-excluded tumours exhibited higher MC than desert/cold ones. MC strongly correlated with genes associated with B-cells, T-helper cells and CTLA4 in CCM, suggesting CAS reprogramming to depend on tumour malignancy. Finally, we identify an immune-suppressive stromal signature in a subset of CMM characterised by the downregulation of key immune checkpoints and pathways. Together, these findings provide a solid foundation for understanding the role of CAS in canine melanoma, specific to cutaneous and mucosal subtypes.

Marginal micrographic surgery without tumour-frozen sections: A quicker margin control surgery for pigmented basal cell carcinomas

Marginal micrographic surgery without tumour-frozen sections: A quicker margin control surgery for pigmented basal cell carcinomas

The assessment of the phototoxic potential of drugs forming complexes with melanin - Screening in vitro studies using normal skin cells with varying pigmentation irradiated by a sunlight simulator

Phototoxic reactions are among the most common skin-related adverse effects induced by drugs. It is believed that the binding of chemicals to melanin biopolymers is a significant factor influencing skin toxicity. The formation of drug-melanin complexes can lead to the accumulation of drugs or their photodegradation products in pigmented cells, potentially affecting phototoxic reactions. Current procedures for assessing the phototoxic potential of drugs are based on tests using immortalized mouse fibroblasts.This study aimed to assess the phototoxic potential of selected drugs that form complexes with melanin (chloroquine, chlorpromazine, doxycycline) using human melanocytes with varying degrees of pigmentation. Parallel research was conducted on human dermal fibroblasts. To induce phototoxicity, cell cultures were irradiated using a sunlight simulator (5 J/cm2 for UVA spectrum). To account for the process of drug accumulation, two experimental models with different incubation times of cells with drugs before irradiation were used. The photo-irritation factor (PIF) was calculated based on NRU and WST-1 screening tests. Additionally, cell viability was examined cytometrically, and analyses of the cell cycle and reduced glutathione levels were conducted.The results indicated that drugs binding with melanin exhibited different levels of cytotoxicity and phototoxicity towards fibroblasts and melanocytes. These observed differences impact the values of PIF, potentially complicating the interpretation of the studies. Additional analyses, such as examining cell subpopulations in the sub-G1 phase and determining the level of reduced glutathione, can enhance the assessment of the phototoxicity of drugs on pigmented cells.

Protective Effects of Keratinocyte-Derived GCSF and CCL20 on UVB-Induced Melanocyte Damage.

The skin microenvironment created by keratinocytes (KC) influences the stress responses of melanocytes (MC) to UVB insults. This study employed RNA sequencing analysis as well as in vitro and in vivo models to elucidate the underlying mechanisms. Our RNA-Seq analysis revealed a statistically significant upregulation of GCSF and CCL20 genes in UVB-irradiated KC, correlating with the protective effects of KC on MC responses to UVB exposure. Recombinant GCSF and CCL20 exhibited the most pronounced modulation of UVB-induced MC responses. These effects included the attenuation of apoptosis and reduction of ROS formation, along with the upregulation of tyrosinase and tyrosinase-related protein-1, which are involved in the melanogenic pathway. ELISA was also used to confirm that UVB could induce the secretion of GCSF and CCL20 from KC. A similar correlation between GCSF and CCL20 expression in KC and tyrosinase levels in MC was observed in UVB-irradiated mouse skin. Our study provides novel insights into the protective role of GCSF and CCL20 in the paracrine effects of KC on UVB-induced MC damage through the modulation of stress response pathways, the MITF-tyrosinase axis, and the regulation of p53. These findings have implications for the development of pharmacological strategies targeting KC-derived paracrine factors for the prevention of skin photodamage.

E-cigarette flavoring chemicals and vehicles adversely impact the functions of pigmented human retinal ARPE-19 cells

Electronic cigarettes (ECs) have been shown to adversely impact the human eye's retinal pigment epithelium (RPE). Flavored e-liquids induced cytotoxicity in unpigmented human ARPE-19 cells independent of nicotine's presence in my previous study. In the current study, human ARPE-19 cells pigmented by sepia melanin were employed to examine the effects of four flavoring chemicals, vanillin, menthol, furanone, and cinnamaldehyde, and EC vehicles propylene glycol (PG)/vegetable glycerin (VG) ratios (0:100, 80:20, 100:0% v/v), on metabolic activity, membrane integrity, oxidative stress, and wound healing capacity of these cells. Results demonstrate that cinnamaldehyde was the most cytotoxic flavoring, and all vehicles showed marked cytotoxicity at the highest concentration of 10%. All four flavorings elicited a significant production of reactive oxygen species (ROS), while the three vehicles did not impact ROS levels. Vanillin significantly (p < 0.05) suppressed wound healing, while furanone and cinnamaldehyde had no effects, although menthol promoted wound healing at the lowest concentration. Moreover, the vehicles with two ratios of 0:100 PG/VG and 80:20 PG/VG suppressed wound healing. Together, these results suggest that vanillin and VG-containing vehicles exert the greatest adverse effects on ARPE-19 cells. These findings underscore the potential harm that exposure to ECs can cause to the human retina.

CD44 facilitates adhesive interactions in airineme-mediated intercellular signaling.

Specialized cellular protrusions facilitate local intercellular communications in various species, including mammals. Among these, airinemes play a crucial role in pigment pattern formation in zebrafish by mediating long-distance Notch signaling between pigment cells. Remarkably, airinemes exhibit large vesicle-like structure at their tips, which are pulled by macrophages and delivered to target cells. The interaction between macrophages and Delta-ligand carrying airineme vesicles is essential for initiating airineme-mediated signaling, yet the molecular detail of this interaction remains elusive. Through high-resolution live imaging, genetic in vivo manipulations and in vitro adhesion assay, we found that adhesive interactions via the extracellular domain of CD44, a class I transmembrane glycoprotein, between macrophages and airineme vesicles are critical for airineme signaling. Mutants lacking the extracellular domain of CD44 lose their adhesiveness, resulting in a significant reduction in airineme extension and pigment pattern defects. Our findings provide valuable insights into the role of adhesive interactions between signal-sending cells and macrophages in a long-range intercellular signaling.

Fish Health Altered by Contaminants and Low Water Temperatures Compounded by Prolonged Regional Drought in the Lower Colorado River Basin, USA.

The goal of this study was to assess health of male Common Carp (carp, Cyprinus carpio) at four sites with a wide range in environmental organic contaminant (EOC) concentrations and water temperatures in Lake Mead National Recreation Area NV/AZ, US, and the potential influence of regional drought. Histological and reproductive biomarkers were measured in 17-30 carp at four sites and 130 EOCs in water per site were analyzed using passive samplers in 2010. Wide ranges among sites were noted in total EOC concentrations (>10Xs) and water temperature/degree days (10Xs). In 2007/08, total polychlorinated biphenyls (tPCBs) in fish whole bodies from Willow Beach (WB) in the free-flowing Colorado River below Hoover Dam were clearly higher than at the other sites. This was most likely due to longer exposures in colder water (12-14 °C) and fish there having the longest lifespan (up to 54 years) for carp reported in the Colorado River Basin. Calculated estrogenicity in water exceeded long-term, environmentally safe criteria of 0.1-0.4 ng/L by one to three orders of magnitude at all sites except the reference site. Low ecological screening values for four contaminants of emerging concern (CEC) in water were exceeded for one CEC in the reference site, two in WB and Las Vegas Bay and three in the most contaminated site LVW. Fish health biomarkers in WB carp had 25% lower liver glycogen, 10Xs higher testicular pigmented cell aggregates and higher sperm abnormalities than the reference site. Sperm from LVW fish also had significantly higher fragmentation of DNA, lower motility and testis had lower percent of spermatozoa, all of which can impair reproduction. Projections from a 3D water quality model performed for WB showed that EOC concentrations due to prolonged regional drought and reduced water levels could increase as high as 135%. Water temperatures by late 21st century are predicted to rise between 0.7 and 2.1 °C that could increase eutrophication, algal blooms, spread disease and decrease dissolved oxygen over 5%.

Pigmented basal cell carcinoma

Pigmented basal cell carcinoma (pBCC) is an uncommon clinical and histopathological variant that is more frequent in darker skin types. The increased number of melanocytes and the subsequent melanin production are responsible for the increased pigmentation in this variant. Clinically, pBCC has a polychromatic nature. The most common clinical mimic of this entity is malignant melanoma. This article focuses on providing dermatologists with insights into this condition.

Functions of TRPs in retinal tissue in physiological and pathological conditions.

The Transient Receptor Potential (TRP) constitutes a family of channels subdivided into seven subfamilies: Ankyrin (TRPA), Canonical (TRPC), Melastatin (TRPM), Mucolipin (TRPML), no-mechano-potential C (TRPN), Polycystic (TRPP), and Vanilloid (TRPV). Although they are structurally similar to one another, the peculiarities of each subfamily are key to the response to stimuli and the signaling pathway that each one triggers. TRPs are non-selective cation channels, most of which are permeable to Ca2+, which is a well-established second messenger that modulates several intracellular signaling pathways and is involved in physiological and pathological conditions in various cell types. TRPs depolarize excitable cells by increasing the influx of Ca2+, Na+, and other cations. Most TRP families are activated by temperature variations, membrane stretching, or chemical agents and, therefore, are defined as polymodal channels. All TPRs are expressed, at some level, in the central nervous system (CNS) and ocular-related structures, such as the retina and optic nerve (ON), except the TRPP in the ON. TRPC, TRPM, TRPV, and TRPML are found in the retinal pigmented cells, whereas only TRPA1 and TRPM are detected in the uvea. Accordingly, several studies have focused on the search to unravel the role of TRPs in physiological and pathological conditions related to the eyes. Thus, this review aims to shed light on endogenous and exogenous modulators, triggered cell signaling pathways, and localization and roles of each subfamily of TRP channels in physiological and pathological conditions in the retina, optic nerve, and retinal pigmented epithelium of vertebrates.

Dynamic changes in pigmentation-related gene expression during morphogenesis in Plectropomus leopardus revealed by comparative transcriptome analysis

Plectropomus leopardus is a valuable marine aquaculture fish, prized by consumers for its high nutritional value and gorgeous appearance. The economic significance of this species is largely influenced by its body color, prompting researchers to become increasingly interested in understanding the mechanisms behind its color formation. However, previous studies have mainly focused on the molecular mechanisms of body color formation during the adult stage of this species. In this study, it was observed that the body color of P. leopardus undergoes four distinct stages during early morphogenesis: transparent (PT), red (PR), red with spots (PRS), and brown with spots (PBS). The L*a*b* values of skin at each stage differ significantly. The number and distribution of erythrophores and melanophores play a crucial role in determining the body colors of P. leopardus. Transcriptome analysis of the skin at these stages revealed multiple differentially expressed genes (DEGs) and signaling pathways related to pigmentation. These pigmentation-related DEGs can be categorized into carotenoid metabolism-related genes (e.g., scarb1, ldlr, plin2, apod, ttc39b, etc), melanin synthesis-related genes (e.g., tyr, tyrp1, dct, pmel, slc7a11, etc), and genes related to pigment cell development (pnp, ednrb, csf1r1, sox10, bnc2). GO and KEGG enrichment analysis indicated that processes like melanin synthesis (e.g., wnt signal pathway, melanogenesis, tyrosine metabolism, etc.), lipid metabolism (e.g., cholesterol metabolism, linoleic acid metabolism, arachidonic metabolism, fatty acid biosynthesis, etc.), and pigment cell development (e.g., pigment cell differentiation, cell development, etc.) are likely involved in the body color formation in P. leopardus. Finally, we proposed a hypothesis regarding carotenoid metabolism in erythrophores and melanin synthesis in melanophores of P. leopardus skin, drawing from existing research reports and transcriptome data. Overall, this study provides a new perspective on the molecular regulatory mechanisms of body color formation in P. leopardus, laying a theoretical foundation for molecular-assisted breeding of body color traits in this species.

Chromatic acclimation in cyanobacteria renders robust photosynthesis and fitness in dynamic light environment: Recent advances and future perspectives.

Cyanobacteria are photoautotrophic organisms that use light and water as a source of energy and electrons, respectively, to fix atmospheric carbon dioxide and release oxygen as a by-product during photosynthesis. However, photosynthesis and fitness of organisms are challenged by seasonal and diurnal fluctuations in light environments. Also, the distribution of cyanobacteria in a water column is subject to changes in the light regime. The quality and quantity of light change significantly in low and bright light environments that either limit photochemistry or result in photoinhibition due to an excess amount of light reaching reaction centers. Therefore, cyanobacteria have to adjust their light-harvesting machinery and cell morphology for the optimal harvesting of light. This adjustment of light-harvesting involves remodeling of the light-harvesting complex called phycobilisome or incorporation of chlorophyll molecules such as chlorophyll d and f into their light-harvesting machinery. Thus, photoacclimation responses of cyanobacteria at the level of pigment composition and cell morphology maximize their photosynthetic ability and fitness under a dynamic light environment. Cyanobacteria exhibit different types of photoacclimation responses that are commonly known as chromatic acclimation (CA). In this work, we discuss different types of CA reported in cyanobacteria and present a molecular mechanism of well-known type 3 CA where phycoerythrin and phycocyanin of phycobilisome changes according to light signals. We also include other aspects of type 3 CA that have been recently studied at a molecular level and highlight the importance of morphogenes, cytoskeleton, and carboxysome proteins. In summary, CA gives a unique competitive benefit to cyanobacteria by increasing their resource utilization ability and fitness.

Phosphodiesterase-4 Inhibitors Increase Pigment Cell Proliferation and Melanization in Cultured Melanocytes and within a 3-Dimensional Skin Equivalent Model

Vitiligo is a common chronic autoimmune disease characterized by white macules and patches of the skin, having a negative impact on patients' life, and without any definitive cure at present. Identification of new compounds to reverse depigmentation is therefore a pressing need for this disease. The pharmacologic compounds phosphodiesterase-4 inhibitors (PDE4i) are small molecules with immunomodulatory properties, used for treatment of inflammatory dermatoses. PDE4i have shown repigmentation effects in vitiligo patients, in some case reports. We characterized the proliferative and melanogenic potential of two known PDE4i, crisaborole and roflumilast, and of a more recently designed compound, PF-07038124. We used two in vitro model systems, the primary human melanocyte culture and a 3D co-cultured skin model (MelanoDermTM), with an exploratory testing platform composed of complementary assays (spectrophotometry, melanin and proliferation assays, immunostaining, Fontana-Masson staining, qRT-PCR, western blot and whole transcriptome RNA-Sequencing). We identified that the treatment with PDE4i was associated with increased melanocyte proliferation and melanization in both in vitro models, and with increase in the melanogenic genes and proteins expression in cultured melanocytes. These effects were found to be enhanced by addition of α-MSH. Our findings support the further evaluation of PDE4i with or without α-MSH agonists in vitiligo trials.

25th IPCC Meeting Special Issue: Translating Basic Pigment Cell Research.

25th IPCC Meeting Special Issue: Translating Basic Pigment Cell Research.

Imaging Golgi‐Apparatus in Colon Cancer Cells by Small Molecule Hydrazone Fluorophore

Herein, we have designed and synthesised a 2,6‐dihydroxybenzoyl‐hydrazone (compound 3) fluorophore through a concise strategy. Molecular dynamics and quantum chemical simulations revealed that long range charge transfer (CT) to be the underlying mechanism for the emissive property of compound 3. Confocal microscopy and cell viability assays confirmed that within 3h, compound 3 homed into the Golgi‐apparatus of colon cancer cells (HCT‐116) selectively compared to the breast (MCF7), lung (A549), cervical (HeLa) cancer cells and non‐cancerous retinal epithelial pigment cells (RPE‐1) with negligible toxicity. This novel fluorophore has potential to image Golgi‐apparatus in a cancer cell specific manner for diagnosis.

Multiple, non-syndromic and non-metastatic pigmented basal cell carcinoma mimicking nodular melanoma: a rare presentation in Indian patient

Basal cell carcinoma is most common cutaneous malignancy having exposure to ultraviolet radiation as the most important predisposing factor. It could be solitary or multiple, in which case they can be associated with variety of syndromes. Out of various clinical types of BCC pigmented bcc can mimic sometimes malignant melanoma and in which case dermoscopy and skin biopsy can be helpful to differentiate. Metastasis of BCC is a rare phenomenon and it depends on various factors like tumour size, site, depth, histological type etc. Here we describe an interesting case of primary, non-syndromic, multifocal BCC which was initially diagnosed as melanoma but later on based on dermoscopy and histology diagnosed and successfully treated as BCC.

Exosomal miR-222-3p derived from dermal papilla cells inhibits melanogenesis in melanocytes by targeting SOX10 in rabbits.

Dermal papilla cells (DPCs) play a pivotal role in hair follicle development and can modulate melanogenesis in melanocytes (MCs) through their microenvironment. Our previous studies have demonstrated that the level of exosomal miR-222-3p derived from DPCs of white Rex rabbits are significantly higher than those of black Rex rabbits. However, the specific role and underlying molecular mechanisms of exosomal miR-222-3p in melanogenesis remain elusive. DPCs and MCs were isolated from hair follicles of Rex rabbits and identified using western blotting (WB) and immunofluorescent staining. Exosomes derived from DPCs (DPCs-exos) were characterized using nanoparticle tracking analysis, transmission electron microscopy, and WB. To investigate cell-cell crosstalk mediated by exosomes, MCs were co-cultured with CM-Dil-labeled DPCs-exos. The expression of miR-222-3p in skin tissue and exosomes was quantitatively assessed using quantitative real-time PCR (qRT-PCR). The transmission of DPCs-secreted exosomal miR-222-3p to MCs was demonstrated using Cy3-labeled miR-222-3p in conjunction with transwell assays. The impact of miR-222-3p on melanin synthesis was evaluated using the NaOH method, CCK-8, and Annexin V-FITC/PI assays. SOX10, a potential target gene regulated by miR-222-3p, was validated using a dual-luciferase reporter assay, site-specific mutation, and WB. Increased levels of miR-222-3p were observed in the skin and DPCs-exos of white Rex rabbits compared to those of black Rex rabbits. Effective internalization of CM-Dil-labeled DPCs-exos by MCs was observed. Furthermore, exosomal miR-222-3p derived from DPCs was transferred to MCs. Functionally, miR-222-3p significantly inhibited MCs proliferation, induced apoptosis and inhibited melanin synthesis. SOX10 was confirmed as a direct target of miR-222-3p in this regulatory cascade. The findings demonstrate that exosomal miR-222-3p, derived from DPCs, suppresses melanogenesis in MCs by targeting SOX10, thus unveiling a novel mechanism of exosome involvement in melanogenesis.

Temperature influences immune cell development and body length in purple sea urchin larvae

Anthropogenic climate change has increased the frequency and intensity of marine heatwaves that may broadly impact the health of marine invertebrates. Rising ocean temperatures lead to increases in disease prevalence in marine organisms; it is therefore critical to understand how marine heatwaves impact immune system development. The purple sea urchin (Strongylocentrotus purpuratus) is an ecologically important, broadcast-spawning, omnivore that primarily inhabits kelp forests in the northeastern Pacific Ocean. The S. purpuratus life cycle includes a relatively long-lived (∼2 months) planktotrophic larval stage. Larvae have a well-characterized cellular immune system that is mediated, in part, by a subset of mesenchymal cells known as pigment cells. To assess the role of environmental temperature on the development of larval immune cells, embryos were generated from adult sea urchins conditioned at 14 °C. Embryos were then cultured in either ambient (14 °C) or elevated (18 °C) seawater. Results indicate that larvae raised in an elevated temperature were slightly larger and had more pigment cells than those raised at ambient temperature. Further, the larval phenotypes varied significantly among genetic crosses, which highlights the importance of genotype in structuring how the immune system develops in the context of the environment. Overall, these results indicate that larvae are phenotypically plastic in modulating their immune cells and body length in response to adverse developmental conditions.

Deferasirox nanosuspension loaded dissolving microneedles for ocular drug delivery

Deferasirox (DFS) is an oral iron chelator that is employed in retinal ailments as a neuroprotectant against retinal injury and thus has utility in treating disorders such as excitoneurotoxicity and age-related macular degeneration (AMD). However, the conventional oral route of administration can present several disadvantages, e.g., the need for more frequent dosing and the first-pass effect. Microneedles (MNs) are minimally invasive systems that can be employed for intrascleral drug delivery without pain and can advantageously replace intravitreal injections therapy (IVT) as well as conventional oral routes of delivery for DFS. In this study, DFS was formulated into a nanosuspension (NS) through wet media milling employing PVA as a stabilizer, which was successfully loaded into polymeric dissolving MNs. DFS exhibited a 4-fold increase in solubility in DFS-NS compared to that of pure DFS. Moreover, the DFS-NSs exhibited excellent short-term stability and enhanced thermal stability, as confirmed through thermogravimetric analysis (TGA) studies. The mechanical characterization of the DFS-NS loaded ocular microneedles (DFS-NS-OcMNs), revealed that the system was sufficiently strong for effective scleral penetration. Optical coherence tomography (OCT) images confirmed the insertion of 81.23 ± 7.35 % of the total height of the MN arrays into full-thickness porcine sclera. Scleral deposition studies revealed 64 % drug deposition after just 5 min of insertion from DFS-NS-loaded ocular microneedles (OcMNs), which was almost 5 times greater than the deposition from pure DFS-OcMNs. Furthermore, both DFS and DFS-NS-OcMN exhibited remarkable cell viability when evaluated on human retinal pigment (ARPE) cells, suggesting their safety and appropriateness for use in the human eye. Therefore, loading DFS-NS into novel MN devices is a promising technique for effectively delivering DFS to the posterior segment of the eye in a minimally invasive manner.