Familial progressive hyperpigmentation: A family resurvey and ultrastructural skin investigation.

Familial progressive hyperpigmentation (FPH) is an autosomal dominant genodermatosis characterized by hyperpigmented patches that increase in size and number with age. Since its initial description in an African-American family in 1971, only a few cases of FPH have been documented. A three-generation family with FPH in central China has also been reported. Here, we resurveyed that Chinese FPH family for a few unusual features including delayed age of onset and noninvolvement of ocular and oral mucosae. Electron microscopic examination of skin from the proband of the family showed that there were more melanosomes in lesional keratinocytes than in perilesional keratinocytes. Additionally, a large number of nonmembrane-bound melanosome complexes were observed in the keratinocytes of hyperpigmented areas, whereas all of the melanosomes were dispersed in the keratinocytes of normally pigmented areas.

Membranous aplasia cutis congenita: A rare case report highlighting clinical presentation, genetic insights, and the need for comprehensive evaluation.

Introduction: Membranous aplasia cutis congenita (MACC) is the most common clinical subtype of aplasia cutis congenita (ACC). It is typified by a localized skin lesion devoid of hair and features a membranous surface. While most MACC individuals do not present with concurrent abnormalities, it can sometimes co-occur with additional physical anomalies and various malformation syndromes. Moreover, the underlying causes of MACC remain elusive. Case presentation: We describe a case of a 6-month-old female infant diagnosed with MACC. The patient presented with a midline skin lesion on the occipital scalp, characterized by a glistening surface and a hair collar sign. Dermoscopic examination revealed specific features, including translucency, telangiectasia, and hypertrichosis. The infant had a history of patent foramen ovale, and further examination uncovered an asymptomatic ventricular septal defect. Whole exome sequencing revealed 20 gene variants relevant to the clinical phenotype of the patient, suggesting a possible association with MACC. Conclusion: MACC is a rare and underreported condition, primarily diagnosed based on its distinctive clinical features. It is imperative to emphasize the significance of thorough evaluations in MACC patients, encompassing developmental, cardiac, neurological, and genetic assessments to facilitate early detection and the exclusion of potentially life-threatening comorbidities. Importantly, genetic characterization, as demonstrated in this case, contributes to our understanding of MACC's etiology and highlights the need for further research in this field.

ABCB6 knockdown suppresses melanogenesis through the GSK3-ß/ß-catenin signaling axis in human melanoma and melanocyte cell lines.

BACKGROUND: Melanogenesis is a multistep process in which melanocytes produce melanin pigments within melanosomes. However, the roles played by the biological factors and pathways in this process are not yet fully understood. OBJECTIVE: To investigate the role of ATP-binding cassette subfamily B member 6 (ABCB6) in the regulation of melanogenesis in vitro. METHODS: Real-time PCR and western blotting were used to assess the knockdown efficiency of ABCB6 in MNT-1 and PIG1 stable cell lines. Cleavage by NaOH was used to determine melanin content, while the number of melanosomes was examined for each stage by transmission electron microscopy. Immunofluorescence microscopy was used to evaluate endogenous protein location. Differentially expressed genes were detected using RNA sequencing, and gene expression was assessed by quantitative real-time PCR. KEGG mapping was used for pathway enrichment analysis. Co-immunoprecipitation was used for protein-protein interactions analysis. RESULTS: We found that ABCB6 inhibition could impair melanocyte maturation and melanin production in human melanoma (MNT-1) and immortalized human melanocyte (PIG1) cell lines. Moreover, ABCB6 knockdown inhibited the protein expression of melanocyte inducing microphthalmia-associated transcription factor (MITF) and its three downstream melanogenic enzymes (TYR, TYRP1 and TYRP2). Mechanistically, we revealed that ABCB6 could interact with and modulate glycogen synthase kinase 3 beta (GSK3-ß) to exert its biological effect on melanogenesis. CONCLUSION: Our findings suggest that ABCB6 is a key regulator of melanogenesis via the GSK3-ß/ß-catenin signaling pathway. However, further in-depth studies are essential to uncover the relationship between ABCB6 and pigmentation disorders.

Circulating Exosomal miR-493-3p Affects Melanocyte Survival and Function by Regulating Epidermal Dopamine Concentration in Segmental Vitiligo.

Circulating exosomal microRNAs have been used as potential biomarkers for various disorders. However, to date, the microRNA expression profile of circulating exosomes in patients with segmental vitiligo (SV) has not been identified. Thus, we aimed to identify the expression profile of circulating exosomal microRNAs and investigate their role in the pathogenesis of SV. Our study identified the expression profile of circulating exosomal microRNAs in SV and selected miR-493-3p as a candidate biomarker whose expression is significantly increased in circulating exosomes and perilesions in patients with SV. Circulating exosomes were internalized by human primary keratinocytes and increased dopamine secretion in vitro. Furthermore, miR-493-3p overexpression in keratinocytes increased dopamine concentration in the culture supernatant, which led to a significant increase in ROS and melanocyte apoptosis as well as a decrease in melanocyte proliferation and melanin synthesis in the coculture system by targeting HNRNPU. We also confirmed that HNRNPU could bind to and regulate COMT, a major degradative enzyme of dopamine. Hence, circulating exosomal miR-493-3p is a biomarker for SV, and the miR-493-3p/HNRNPU/COMT/dopamine axis may contribute to melanocyte dysregulation in the pathogenesis of SV.

Methylcobalamin Protects Melanocytes from H2O2-Induced Oxidative Stress by Activating the Nrf2/HO-1 Pathway.

PURPOSE: Oxidative stress is considered a major determinant in the pathogenesis of vitiligo. Methylcobalamin (MeCbl) is an activated form of vitamin B12 that regulates inflammatory factors, counters oxidative stress, and reduces apoptosis in many disease models. However, the specific mechanism of MeCbl repigmentation against vitiligo is unknown. In this study, we explored the effect of MeCbl on melanocytes following hydrogen peroxide (H2O2)-induced oxidative stress. METHODS: We established an oxidative stress model using the immortalized human normal melanocyte cell line PIG1. We used a Cell Counting Kit-8 (CCK-8) to detect drug cytotoxicity, and we measured the melanin content of cells using the NaOH method. Intracellular oxidative damage was assessed by flow cytometry and antioxidant enzyme detection kits. In addition, we assessed the presence of apoptosis by flow cytometry and Western blots. We explored the underlying mechanisms of MeCbl during oxidative stress in melanocytes by analyzing the results of experiments based on real-time quantitative polymerase chain reaction (RT-qPCR), Western blotting, and laser scanning confocal immunofluorescence microscopy. Finally, we repeated the experiments after applying an inhibitor to block the Nrf2 pathway. RESULTS: We found that MeCbl treatment enhanced cell viability, increased melanin content, reduced intracellular reactive oxygen species (ROS) accumulation, increased the activities of antioxidant enzyme superoxide dismutase (SOD) and catalase (CAT), reduced melanocyte apoptosis, and up-regulated the expression of the Nrf2/HO-1 pathway. Moreover, the protective effects of MeCbl were significantly weakened after inhibiting the Nrf2/HO-1 pathway. CONCLUSION: Our results indicate that MeCbl attenuated the H2O2-induced oxidative stress in melanocytes by activating the Nrf2/HO-1 pathway, this suggests that MeCbl may be an effective treatment against vitiligo.

Identifying an lncRNA-Related ceRNA Network to Reveal Novel Targets for a Cutaneous Squamous Cell Carcinoma.

A cutaneous squamous cell carcinoma (cSCC) derived from keratinocytes is the second most common cause of non-melanoma skin cancer. The accumulation of the mutational burden of genes and cellular DNA damage caused by the risk factors (e.g., exposure to ultraviolet radiation) contribute to the aberrant proliferation of keratinocytes and the formation of a cSCC. A cSCC encompasses a spectrum of diseases that range from recursor actinic keratosis (AK) and squamous cell carcinoma (SCC) in situ (SCCIS) to invasive cSCCs and further metastatic SCCs. Emerging evidence has revealed that lncRNAs are involved in the biological process of a cSCC. According to the ceRNA regulatory theory, lncRNAs act as natural miRNA sponges and interact with miRNA response elements, thereby regulating the mRNA expression of their down-stream targets. This study was designed to search for the potential lncRNAs that may become potential therapeutic targets or biomarkers of a cSCC. Considering the spirit of the study to be adequately justified, we collected microarray-based datasets of 19 cSCC tissues and 12 normal skin samples from the GEO database (GSE42677 and GSE45164). After screening the differentially expressed genes via a limma package, we identified 24 differentially expressed lncRNAs (DElncRNAs) and 3221 differentially expressed mRNAs (DEmRNAs). The miRcode, miRTarBase, miRDB and TargetScan databases were used to predict miRNAs that could interact with DElncRNAs and DEmRNAs. A total of 137 miRNA-lncRNA and 221 miRNA-mRNA pairs were retained in the ceRNA network, consisting of 31 miRNAs, 11 DElncRNAs and 155 DEmRNAs. For the functional analysis, the top enriched biological process was enhancer sequence-specific DNA binding in Gene Ontology (GO) terms. The FoxO signaling pathway, autophagy and cellular senescence were the top enrichment terms based on a Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. The combination of a STRING tool and Cytoscape software (plug-in MCODE) identified five core mRNAs and built a core mRNA-associated ceRNA network. The expression for five identified core mRNAs and their related nine lncRNAs was validated using the external dataset GSE7553. Finally, one lncRNA HLA-F-AS1 and three mRNAs named AGO4, E2F1 and CCND1 were validated with the same expression patterns. We speculate that lncRNA HLA-F-AS1 may sponge miR-17-5p or miR-20b-5p to regulate the expression of CCND1 and E2F1 in the cSCC. The present study may provide potential diagnostic and therapeutic targets for cSCC patients.