Pigment Cell & Melanoma Research最新文献

Oculocutaneous albinism type 2 (OCA-2, OMIM: 203200) is associated with variants in the OCA2 gene. In this study, we aimed to re-classify variants of uncertain significance (VUS) in OCA2 by evaluating subcellular localization and channel activity through multiplex assays of variant effect (MAVEs). Following the ClinGen guidelines for PS3 evidence, we selected 13 OCA2 variants from ClinVar (6 benign/likely benign [B/LB] and 7 pathogenic/likely pathogenic [P/LP]) for OddsPath analysis. The P/LP variants exhibited abnormal functions, while the B/LB variants demonstrated normal functions, supporting the application of “PS3_moderate” evidence for VUS re-classification. In our functional evaluation of 30 VUS identified in 38 individuals with suspected OCA-2 by trio whole-exome sequencing, we observed 6 VUS with abnormal localization and 11 with abnormal channel activity. Based on PS3_moderate evidence, 8 VUS were re-classified as LP, while 22 remained VUS. Consequently, 7 out of 38 previously undiagnosed patients received a molecular diagnosis of OCA-2. These MAVEs offer a robust approach for curating OCA2 VUS, enhancing diagnostic accuracy, and informing genetic counseling. Additionally, this variant cohort is a valuable resource for public databases.

Current NICE guidelines state that in high-risk melanoma patients, imaging should not be offered before SLNB unless lymph node or distant metastases are suspected. Our experience has been that in patients with pT3b, pT4a and pT4b melanomas, the rate of management-changing findings on axial imaging prior to SLNB was high and that ‘stage before operating’ is a better approach. We now offer full axial imaging as staging to all high-risk melanoma patients prior to SLNB and advise other skin cancer MDTs to follow this approach.

Isolating high-quality viable single cells from mouse tail skin, a well-established model for studying skin cells and melanoma pathogenesis, is challenging due to the presence of dense connective tissue and hair follicles. Single-cell RNA sequencing (scRNA-seq) is a powerful tool for studying skin cell heterogeneity. However, the lack of a robust protocol for the efficient generation of highly viable single-cell suspension from mouse tail skin has limited its application for studying melanocyte-interacting cells and characterizing the melanocyte niche. We developed a robust protocol for generating highly viable single-cell suspensions from mouse tail skin, facilitating single-cell transcriptomic profiling of keratinocytes, melanocytes, and fibroblasts. We demonstrate the successful isolation of melanocytes and other melanocyte-interacting cells using our protocol and a proof-of-concept scRNA-seq study for interrogating the melanocyte niche. Our protocol employs a two-stage enzyme dissociation step, followed by debris removal and subsequent live cell enrichment, to obtain a single-cell suspension with high cell viability. This straightforward protocol enables the isolation of viable single cells from mouse tail skin for downstream scRNA-seq studies. Further, this approach allows comprehensive analysis of the melanocyte niche and melanocyte-interacting cells, potentially aiding in identifying the melanoma cell of origin.

Reptiles showcase an extensive array of skin colours and patterns, yet little is known about the genetics of reptile colouration. Here, we investigate the genetic basis of the Clown colour morph found in captive-bred ball pythons (Python regius) to study skin pigmentation and patterning in snakes. We obtained samples by crowdsourcing shed skin from commercial breeders and hobbyists. We applied a case–control design, whole-genome pool sequencing, variant annotation, histological analyses, and electron microscopy imaging. We identified a missense mutation in a transmembrane region of the melanocortin-1 receptor (MC1R) associated with the Clown phenotype. In classic avian and mammalian model species, MC1R is known for controlling the type and amount of melanin produced. In contrast, our results suggest that MC1R signalling might play a key role in pattern formation in ball pythons, affecting xanthophore–melanophore distribution. This work highlights the varied functions of MC1R across different vertebrate lineages and promotes a novel model system to study reptile colouration.

Both germline and somatic variants contribute to the genetic background and pathogenesis of melanoma. Germline variants include the presence of rare pathogenic or likely pathogenic variants of high, medium, and low penetrance melanoma-predisposing genes. Rare variants of high penetrance melanoma-predisposing genes are associated with melanoma development, whereas the medium and low penetrance predisposing genes can significantly increase melanoma risk. In this study, we clarified the germline genetic background of a Hungarian melanoma cohort (n = 17). Using a gene panel of 30 melanoma-predisposing genes, germline genetic variants were identified in 10 of the 17 patients (58.82%). A novel, likely pathogenic, missense variant (p.Y143C) in a medium penetrance melanoma-predisposing gene, melanocortin 1 receptor gene (MC1R), and two novel, likely pathogenic nonsense variants in low penetrance genes, p.Q218Ter in caspase 8 (CASP8) and p.Q40Ter in the fat mass- and obesity-associated (FTO) gene were detected. This study highlights the importance of elucidating the germline genetic background of melanoma, which may improve prediction of individual risk and the risk of family members and to optimize preventive, screening, and therapeutic measures for each patient and melanoma-prone families.

Lipid droplets are fat storage organelles composed of a protein envelope and lipid-rich core. Regulation of this protein envelope underlies differential lipid droplet formation and function. In melanoma, lipid droplet formation has been linked to tumor progression and metastasis, but it is unknown whether lipid droplet proteins play a role. To address this, we performed proteomic analysis of the lipid droplet envelope in melanoma. We found that lipid droplet proteins were differentially enriched in distinct melanoma states; from melanocytic to undifferentiated. DHRS3, which converts all-trans-retinal to all-trans-retinol, is upregulated in the MITF^LO/undifferentiated/neural crest-like melanoma cell state and reduced in the MITF^HI/melanocytic state. Increased DHRS3 expression is sufficient to drive MITF^HI/melanocytic cells to a more undifferentiated/invasive state. These changes are due to retinoic acid-mediated regulation of melanocytic genes. Our data demonstrate that melanoma cell state can be regulated by expression of lipid droplet proteins which affect downstream retinoid signaling.

Post-inflammatory hyperpigmentation (PIH) is a very common disorder of cutaneous hyperpigmentation, which poses a persistent management challenge in the fields of dermatology and esthetics. This study was designed to explore the anti-melanogenic and anti-inflammatory effects of Bay 11-7082, an NF-κB inhibitor, using small-molecule screening, to determine its potential application for PIH prevention. The molecular mechanisms were investigated in vitro and ex vivo in epidermis-humanized mice using melanin content, RT-PCR, and immunoblotting. Bay 11-7082 suppressed proinflammatory cytokines and ameliorated 2,4-dinitrofluorobenzene (DNFB)-induced contact dermatitis on day 15. The suppression of melanin synthesis by Bay 11-7082 was attributed to the reduction of MITF, which was induced by extracellular signal-regulated kinase activation. Bay 11-7082 reduced epidermal melanin accumulation in UVB-stimulated ex vivo human epidermis as well as in the ear and tail skin of K14-stem cell factor (SCF) transgenic mice. Topical administration of Bay 11-7082 improved PIH on day 35 in the post-DNFB dorsal skin of K14-SCF transgenic mice. In conclusion, Bay 11-7082 can be considered a promising candidate for the development of a preventive topical agent for PIH.