The long noncoding RNA MALAT1 suppresses miR-211 to confer protection from ultraviolet-mediated DNA damage in vitiligo epidermis by upregulating sirtuin 1

Non-coding RNAs (miRNAs - circRNAs - lncRNAs) and genes interact with the regulation of vitiligo

Vitiligo is a chronic skin disorder characterized by the loss of melanocytes, resulting in depigmented patches on the skin. The molecular mechanisms underlying vitiligo remain incompletely understood, with recent studies highlighting the role of non-coding RNAs in disease pathogenesis. To identify and analyze the roles of miRNAs, (circular RNAs) circRNAs, and (long non-coding RNAs) lncRNAs in the pathogenesis of vitiligo, focusing on their interactions with key coding genes and pathways. We utilized Microarray data from the GSE65127 and GSE75819 datasets in the Gene Expression Omnibus (GEO) database to identify differentially expressed genes (DEGs) related to Vitiligo. The analysis was conducted using GEO2R for identifying upregulated and downregulated genes. Protein-protein interaction (PPI) networks were constructed using STRING and further analyzed with Cytoscape and CytoHubba. Gene Ontology (GO), disease pathways, Disease gene associations, and phenotypes are determined by many online software. miRNAs and cirRNas, lncRNAs were predicted using bioinformatics tools. The constructed network identified AKT1 as a central hub, hsa-miR-140-3p assumes a critical role by interacting with both AKT1 and CTSD, while circRNAs such as hsa_circ_0020776, hsa_circ_0033552, and hsa_circ_0020773 significantly modulate these interactions. Also, hsa-miR-921 is highly effective in binding to AKT1, as well as to hsa_circ_0033546 and hsa_circ_0033547. lncRNAs, including AFAP1-AS1 and MALAT1, contribute to the network by establishing connections with the mRNA of target genes. we determined two genes, two miRNAs, and 5 circRNAs may serve as potential biomarkers or therapeutic targets for vitiligo.

A comprehensive outline of the role of non-coding RNAs in vitiligo

Vitiligo is a common skin depigmentation condition caused by selective destruction of melanocytes. It is regarded as a polygenic disorder. In addition to protein-coding loci, non-coding regions of the genome contribute to the pathogenesis of vitiligo. A bulk of evidence highlights contribution of different classes of non-coding RNAs in this condition. Expression profile of different non-coding RNAs has been evaluated in the plasma, serum, blood cells and skin samples of patients with vitiligo. Notably, these transcripts not only partake the pathogenesis of vitiligo, but also are regarded as putative targets for prospective treatment strategies for this disorder. The current review focuses on depicting the role of miRNAs, long non-coding RNAs and circular RNAs in the etiology of vitiligo. Moreover, we discuss the shared functions of these transcripts in the pathogenesis of vitiligo and melanoma.

Genetics and epigenetics in vitiligo

Vitiligo, a complex autoimmune disorder characterized by melanocyte destruction, arises from an intricate interplay of genetic, epigenetic, immune, and environmental factors. Genome-wide association studies (GWAS) have identified over 50 susceptibility loci, including key genes within the MHC region and those involved in immunity, oxidative stress, and melanogenesis. Concurrently, epigenetic research has unraveled regulatory networks critical to vitiligo pathogenesis, with a focus on DNA methylation and non-coding RNAs (e.g., microRNAs, long non-coding RNAs, and circular RNAs). These advancements provide deeper insights into gene regulation, immune processes, and cellular dynamics. This review integrates findings from genetic and epigenetic studies to offer a comprehensive understanding of molecular mechanisms of vitiligo, paving the way for innovative, personalized therapeutic approaches.

Bioinformatic analysis of ferroptosis related biomarkers and potential therapeutic targets in vitiligo

Vitiligo is a complex autoimmune skin disorder characterized by depigmentation and immune dysregulation. To elucidate the role of ferroptosis-related genes (FRGs) in vitiligo, we conducted a comprehensive analysis of gene expression data from the GSE53146 and GSE65127 datasets obtained from the GEO database. We identified 31 differentially expressed FRGs (DE-FRGs), with 21 genes upregulated and 10 downregulated. Functional enrichment analysis revealed that these DE-FRGs are significantly involved in oxidative stress, immune regulation, and vitiligo-associated signaling pathways. Utilizing machine learning approaches, including LASSO and SVM-RFE, we identified four key marker genes (ALOX5, SNCA, SLC1A4, and IL33) with strong diagnostic potential. Immune landscape analysis demonstrated that these marker genes influence immune cell composition, particularly showing correlations with CD8 + T cells and regulatory T cells. Furthermore, drug-gene interaction analysis proposed potential therapeutic targets, while ceRNA network analysis uncovered intricate regulatory relationships involving miRNAs and lncRNAs. Collectively, our findings provide novel insights into the molecular mechanisms underpinning vitiligo and suggest new avenues for diagnostic and therapeutic development.

An Overview of the Biological Complexity of Vitiligo

Vitiligo is a skin disease that affects all ethnicities and genders and is characterized by the loss of pigment essentially due to the selective loss of melanocytes. Although it is generally considered a systemic disease associated with polymorphisms in genes involved in the immune response, vitiligo is also considered an oxidative imbalance-associated disease. It represents a multifactorial pathology in which some genetic predisposition and epigenetic factors coupled with some critical biochemical and molecular pathways could play a pivotal role. The aim of this work was thus to review some of the fine cellular mechanisms involved in the etiopathogenesis of vitiligo, mainly focusing on the nonimmunological ones, extensively highlighted elsewhere. We took into consideration, in addition to oxidative stress, both the cause and the hallmark of the pathology, some less investigated aspects such as the role of epigenetic factors, e.g., microRNAs, of receptors of catecholamines, and the more recently recognized role of the mitochondria. Sex differences associated with vitiligo have also been investigated starting from sex hormones and the receptors through which they exert their influence. From literature analysis, a picture seems to emerge in which vitiligo can be considered not just a melanocyte-affecting disease but a systemic pathology that compromises the homeostasis of a complex tissue such as the skin, in which different cell types reside playing multifaceted physiological roles for the entire organism. The exact sequence of cellular and subcellular events associated with vitiligo is still a matter of debate. However, the knowledge of the individual biological factors implicated in vitiligo could help physicians to highlight useful innovative markers of progression and provide, in the long run, new targets for more tailored treatments based on individual manifestations of the disease.

Post-translational modification in the pathogenesis of vitiligo

Vitiligo is a chronic dermatological condition marked by the loss of skin pigmentation. Its complex etiology involves multiple factors and has not been completely elucidated. Protein post-translational modification pathways have been proven to play a significant role in inflammatory skin diseases, yet research in the context of vitiligo remains limited. This review focuses on the role of post-translational modifications in vitiligo pathogenesis, especially their impact on cellular signaling pathways related to immune response and melanocyte survival. Current therapeutic strategies targeting these pathways are discussed, emphasizing the potential for novel treatments in vitiligo management.

Stem cell factor-mediated upregulation of SIRT1 protects melanin-deprived keratinocytes against UV-induced DNA damage in individuals with vitiligo

Despite the loss of melanocytes, individuals with vitiligo have a significantly lower risk of developing skin malignancies compared to ethnicity-matched controls. The study investigated the molecular mechanisms that protect skin cells (keratinocytes) from UV-B-induced DNA damage in individuals with vitiligo. The study found that upregulation of stem cell factor (SCF) signaling significantly reduced γ-H2AX positivity and cyclobutane pyrimidine dimer formation and improved mitochondrial health (elongated mitochondria, reduced reactive oxygen species [ROS] and lipid peroxidation) in keratinocytes upon UV-B exposure. Interestingly, SCF treatment also reduced lipid droplet accumulation and triacylglyceride levels by upregulating lipoprotein lipase (LPL). Further, siLPL increased DNA damage and lipid droplet (LD) accumulation, while NO-1886, an LPL agonist, reversed both, suggesting a direct link between lipid metabolism and DNA damage. Downregulation of NAD-dependent deacetylase sirtuin1 (SIRT1) with siRNA or with Ex-527, a pharmacological inhibitor of SIRT1, diminished the protective effects mediated by SCF and NO-1886, suggesting SIRT1 to be the final effector protein in the SCF-LPL-SIRT1 signaling axis. Analysis of clinical samples of vitiligo corroborated the upregulation of SCF and LPL in lesional epidermis. In conclusion, our study demonstrates a novel SCF-LPL-SIRT1 signaling axis that confers protection to vitiligo keratinocytes from the harmful effects of UV-B radiation.

FOXO3 induces TUG1-mediated miR-375/GATA3 signaling axis to promote the survival of melanocytes in vitiligo

Vitiligo is characterized by the depletion of melanocytes due to the activation of CD8+ T cells. Taurine-upregulated gene 1 (TUG1), a long noncoding RNA, is involved in melanogenesis. This study aimed to explore the role and mechanism of TUG1 in vitiligo. RT-qPCR and western blot analyses demonstrated decreased TUG1 levels and increased miR-375 levels in patients with vitiligo. MTT and transwell assays indicated that TUG1 upregulation facilitated melanocyte survival and inhibited CD8+ T cell migration. Dual luciferase reporter and chromatin immunoprecipitation assays verified that Forkhead box O3 (FOXO3) directly interacted with the TUG1 promoter, leading to the positive regulation of TUG1 expression. In addition, FOXO3 promoted melanocyte survival by enhancing the transcription of TUG1. Luciferase reporter assay and RNA immunoprecipitation assay confirmed that TUG1 upregulated GATA binding protein 3 (GATA3) expression by targeting miR-375. TUG1 facilitated melanocyte survival by regulating the miR-375/GATA3 axis. In vitiligo, melanocyte survival is promoted by the induction of the TUG1-mediated miR-375/GATA3 axis by FOXO3, which offers new therapeutic targets for vitiligo treatment.

Long noncoding RNA MALAT1 in dermatologic disorders: a comprehensive review

Dermatologic disorders, affecting the integumentary system, involve diverse molecular mechanisms such as cell proliferation, apoptosis, inflammation and immune responses. Long noncoding RNAs, particularly Metastasis-Associated Lung Adenocarcinoma Transcript 1 (MALAT1), are crucial regulators of gene expression. MALAT1 influences inflammatory responses, immune cell function and signaling pathways, impacting various physiological and pathological processes, including dermatologic disorders. Dysregulation of MALAT1 is observed in skin conditions like psoriasis, atopic dermatitis and systemic lupus erythematosus. However, its precise role remains unclear. This review consolidates knowledge on MALAT1's impact on skin biology and pathology, emphasizing its potential diagnostic and therapeutic implications in dermatologic conditions.

Exosome-derived microRNAs: emerging players in vitiligo

Exosome-derived microRNAs (miRNAs) are biomacromolecules and nanoscale extracellular vesicles originating from intracellular compartments that are secreted by most cells into the extracellular space. This review examines the formation and function of exosomal miRNAs in biological information transfer, explores the pathogenesis of vitiligo, and highlights the relationship between exosomal miRNAs and vitiligo. The aim is to deepen the understanding of how exosomal miRNAs influence immune imbalance, oxidative stress damage, melanocyte-keratinocyte interactions, and melanogenesis disorders in the development of vitiligo. This enhanced understanding may contribute to the development of potential diagnostic and therapeutic options for vitiligo.

Exploring regulatory mechanisms on miRNAs and their implications in inflammation-related diseases

This comprehensive exploration delves into the pivotal role of microRNAs (miRNAs) within the intricate tapestry of cellular regulation. As potent orchestrators of gene expression, miRNAs exhibit diverse functions in cellular processes, extending their influence from the nucleus to the cytoplasm. The complex journey of miRNA biogenesis, involving transcription, processing, and integration into the RNA-induced silencing complex, showcases their versatility. In the cytoplasm, mature miRNAs finely tune cellular functions by modulating target mRNA expression, while their reach extends into the nucleus, influencing transcriptional regulation and epigenetic modifications. Dysregulation of miRNAs becomes apparent in various pathologies, such as cancer, autoimmune diseases, and inflammatory conditions. The adaptability of miRNAs to environmental signals, interactions with transcription factors, and involvement in intricate regulatory networks underscore their significance. DNA methylation and histone modifications adds depth to understanding the dynamic regulation of miRNAs. Mechanisms like competition with RNA-binding proteins, sponging, and the control of miRNA levels through degradation and editing contribute to this complex regulation process. In this review, we mainly focus on how dysregulation of miRNA expression can be related with skin-related autoimmune and autoinflammatory diseases, arthritis, cardiovascular diseases, inflammatory bowel disease, autoimmune and autoinflammatory diseases, and neurodegenerative disorders. We also emphasize the multifaceted roles of miRNAs, urging continued research to unravel their complexities. The mechanisms governing miRNA functions promise advancements in therapeutic interventions and enhanced insights into cellular dynamics in health and disease.

Non-coding RNAs as skin disease biomarkers, molecular signatures, and therapeutic targets

Non-coding RNAs (ncRNAs) are emerging as biomarkers, molecular signatures, and therapeutic tools and targets for diseases. In this review, we focus specifically on skin diseases to highlight how two classes of ncRNAs-microRNAs and long noncoding RNAs-are being used to diagnose medical conditions of unclear etiology, improve our ability to guide treatment response, and predict disease prognosis. Furthermore, we explore how ncRNAs are being used as both as drug targets and associated therapies have unique benefits, risks, and challenges to development, but offer a distinctive promise for improving patient care and outcomes.

Role of non‑coding RNAs in UV‑induced radiation effects (Review)

Ultraviolet (UV) is divided into UVA (long-wave, 320-400 nm), UVB (middle-wave, 280-320 nm) and UVC (short-wave, 100-280 nm) based on wavelength. UV radiation (UVR) from sunlight (UVA + UVB) is a major cause of skin photodamage including skin inflammation, aging and pigmentation. Accidental exposure to UVC burns the skin and induces skin cancer. In addition to the skin, UV radiation can also impair visual function. Non-coding RNAs (ncRNAs) are a class of functional RNAs that do not have coding activity but can control cellular processes at the post-transcriptional level, including microRNA (miRNA), long non-coding RNA (lncRNA) and circulatory RNA (circRNA). Through a review of the literature, it was determined that UVR can affect the expression of various ncRNAs, and that this regulation may be wavelength specific. Functionally, ncRNAs participate in the regulation of photodamage through various pathways and play pathogenic or protective regulatory roles. In addition, ncRNAs that are upregulated or downregulated by UVR can serve as biomarkers for UV-induced diseases, aiding in diagnosis and prognosis assessment. Therapeutic strategies targeting ncRNAs, including the use of natural drugs and their extracts, have shown protective effects against UV-induced photodamage. In the present review, an extensive summarization of previous studies was performed and the role and mechanism of ncRNAs in UV-induced radiation effects was reviewed to aid in the diagnosis and treatment of UV-related diseases.

LncRNA MALAT1 in Keratinocyte function: A review of recent advances

Keratinocytes, the principal epidermal cells, play a vital role in maintaining the structural integrity and functionality of the skin. Beyond their protective role, keratinocytes are key contributors to the process of wound healing, as they migrate to injury sites, proliferate, and generate new layers of epidermis, facilitating tissue repair and remodeling. Moreover, keratinocytes actively participate in the skin's immune responses, expressing pattern recognition receptors (PRRs) to detect microbial components and interact with immune cells to influence adaptive immunity. Keratinocytes express a diverse repertoire of signaling pathways, transcription factors, and epigenetic regulators to regulate their growth, differentiation, and response to environmental cues. Among these regulatory elements, long non-coding RNAs (lncRNAs) have emerged as essential players in keratinocyte biology. LncRNAs, including MALAT1, play diverse roles in gene regulation and cellular processes, influencing keratinocyte proliferation, differentiation, migration, and response to environmental stimuli. Dysregulation of specific lncRNAs such as MALAT1 can disrupt keratinocyte homeostasis, leading to impaired differentiation, compromised barrier integrity, and contributing to the pathogenesis of various skin disorders. Understanding the intricate interplay between lncRNAs and keratinocytes offers promising insights into the molecular underpinnings of skin health and disease, with potential implications for targeted therapies and advancements in dermatological research. Hence, our objective is to provide a comprehensive summary of the available knowledge concerning keratinocytes and their intricate relationship with MALAT1.

Association between miR-202, miR-211, and miR-1238 gene polymorphisms and risk of vitiligo

Vitiligo, as a common pigment defect in the skin, hair, and mucous membranes, results from the destruction of melanocytes. Recent investigations have shown that miRNA dysregulation contributes in the pathogenesis of vitiligo. Therefore, in this research, our aim is to explore the relationship between miR-202 rs12355840, miR-211 rs8039189, and miR-1238 rs12973308 polymorphisms and susceptibility to vitiligo. A total number of 136 vitiligo patients and 129 healthy individuals as a control group were included in this research. The salting out approach was implemented to extraction genomic DNA. The genetic polymorphisms of miR-202 rs12355840, miR-211 rs8039189, and miR-1238 rs12973308 were determined using PCR-RFLP approach. The findings revealed that miR-202 rs12355840 polymorphism under codominant (CT and TT genotypes), dominant, recessive, overdominant, and also allelic models is correlated with increased risk of vitiligo. In addition, codominant, dominant, overdominant, as well as allelic models of miR-211 rs8039189 polymorphism decrease risk of vitiligo. No significant relationship was observed between the miR-1238 rs12973308 polymorphism and susceptibility to vitiligo. The miR-211 rs8039189 polymorphism may serve a protective effect on vitiligo development and miR-202 rs12355840 polymorphism may act as a risk factor for vitiligo susceptibility.

Increased Expression of Long Noncoding RNA LOC100506314 in T cells from Patients with Nonsegmental Vitiligo and Its Contribution to Vitiligo Pathogenesis

This study aimed to identify the abnormal expression of long noncoding RNAs (lncRNAs) in T cells from patients with vitiligo and to investigate their functional roles in the immune system. Using microarray analysis, the expression levels of RNA transcripts in T cells from patients with vitiligo and controls were compared. We identified several genes and validated their expression levels in T cells from 41 vitiligo patients and 41 controls. The biological functions of the lncRNAs were studied in a transfection study using an RNA pull-down assay, followed by proteomic analysis and western blotting. The expression levels of 134 genes were significantly increased, and those of 142 genes were significantly decreased in T cells from vitiligo patients. After validation, six genes had increased expression, and three genes had decreased expression in T cells from patients with vitiligo. T-cell expression of LOC100506314 was increased in vitiligo, especially CD4+, but not CD8+ T cells. The expression levels of LOC100506314 in CD4+ T cells was positively and significantly associated with the severity of vitiligo. LOC100506314 was bound to the signal transducer and activator of transcription 3 (STAT3) and macrophage migration inhibitory factor (MIF). Enhanced expression of LOC100506314 inhibited the phosphorylation of STAT3, protein kinase B (AKT), and extracellular signal-regulated protein kinases (ERK), as well as the levels of nuclear protein of p65 and the expression of IL-6 and IL-17 in Jurkat cells and T cells from patients with vitiligo. In conclusion, this study showed that the expression of LOC100506314 was elevated in CD4+ T cells from patients with vitiligo and associated the severity of vitiligo. LOC100506314 interacted with STAT3 and MIF and inhibited IL-6 and IL-17 expression by suppressing the STAT3, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), AKT, and ERK pathways. Enhanced expression of LOC100506314 in T cells may be a potential treatment strategy for vitiligo.

Critical genes in human photoaged skin identified using weighted gene co-expression network analysis

Photoaging is unique to the skin and is accompanied by an increased risk of tumors. To explore the transcriptomic regulatory mechanism of skin photoaging, the epidermis, and dermis of 16 healthy donors (eight exposed and eight non-exposed) were surgically excised and detected using total RNA-Seq. Weighted gene co-expression network analysis (WGCNA) identified the most relevant modules with exposure. The hub genes were identified using correlation, p-value, and enrichment analysis. The critical genes were identified using Support Vector Machine-Recursive Feature Elimination (SVM-RFE) and least absolute shrinkage and selection operator (LASSO) regression, then enriched using single-gene GSEA. A competitive endogenous RNA (ceRNA) network was constructed and validated using qRT-PCR. Compared with non-exposed sites, 430 mRNAs, 168 lncRNAs, and 136 miRNAs were differentially expressed in the exposed skin. WGCNA identified the module MEthistle and 12 intersecting genes from the 71 genes in this module. The enriched pathways were related to muscle. The critical genes were KLHL41, MYBPC2, and ERAP2. Single-gene GSEA identified the Hippo signaling pathway, basal cell carcinoma, cell adhesion molecules, and other pathways. Six miRNAs and 18 lncRNAs related to the critical genes constituted the ceRNA network and were verified using qPCR. The differential expression of KLHL41, MYBPC2, and ERAP2 at the protein level was verified using immunohistochemistry. KLHL41, MYBPC2, and ERAP2 genes are related to skin photoaging. The prediction model based on the three critical genes can indicate photoaging. These critical genes may have a role in skin photoaging by regulating cell growth, intercellular adhesion, and substance metabolism pathways.

The Essential Role of microRNAs in Inflammatory and Autoimmune Skin Diseases-A Review

The etiopathogenesis of autoimmune skin diseases is complex and still not fully understood. The role of epigenetic factors is emphasized in the development of such diseases. MicroRNAs (miRNAs), a group of non-coding RNAs (ncRNAs-non-coding RNAs), are one of the important post-transcriptional epigenetic factors. miRNAs have a significant role in the regulation of the immune response by participating in the process of the differentiation and activation of B and T lymphocytes, macrophages, and dendritic cells. Recent advances in research on epigenetic factors have provided new insights into the pathogenesis and potential diagnostic and therapeutic targets of many pathologies. Numerous studies revealed a change in the expression of some microRNAs in inflammatory skin disorders, and the regulation of miRNA expression is a promising therapeutic goal. This review presents the state of the art regarding changes in the expression and role of miRNAs in inflammatory and autoimmune skin diseases, including psoriasis, atopic dermatitis, vitiligo, lichen planus, hidradenitis suppurativa, and autoimmune blistering diseases.

MicroRNAs: Emerging players in the pathogenesis of vitiligo

Vitiligo is an autoimmune skin disease characterized by presence of pale patchy areas of depigmentation. MicroRNAs (miRNAs) are important regulators of gene expression and play significant roles in diverse biological and pathological processes. Accumulating evidence has shown that miRNAs were differentially expressed in skin lesions and peripheral blood mononuclear cells of patients with vitiligo. In particular, miRNAs are significantly correlated with the development and progression of vitiligo. The abundance of some miRNAs in serum was also correlated with the vitiligo lesion severity, indicating that miRNAs might serve as prognostic biomarkers. Importantly, the direct involvement of miRNAs in the pathogenesis of vitiligo has been demonstrated. For example, increased expression of miR-25 contributes to vitiligo through promoting the dysfunction and oxidative stress-induced destruction of melanocytes. However, there are limited studies on the function and mechanism of deregulated miRNAs in vitiligo. Further studies are required to establish clinical applications of miRNAs for vitiligo. More in-depth investigations of miRNAs are needed for the understanding of the pathogenesis of vitiligo and the development of novel therapeutic targets. This present review summarizes the current literature on the deregulation and pathogenic roles of miRNAs in vitiligo. We also highlight the potential clinical applications of miRNAs in patients with vitiligo.

Monoterpenes as Sirtuin-1 Activators: Therapeutic Potential in Aging and Related Diseases

Sirtuin 1 (SIRT) is a class III, NAD+-dependent histone deacetylase that also modulates the activity of numerous non-histone proteins through deacylation. SIRT1 plays critical roles in regulating and integrating cellular energy metabolism, response to stress, and circadian rhythm by modulating epigenetic and transcriptional regulation, mitochondrial homeostasis, proteostasis, telomere maintenance, inflammation, and the response to hypoxia. SIRT1 expression and activity decrease with aging, and enhancing its activity extends life span in various organisms, including mammals, and improves many age-related diseases, including cancer, metabolic, cardiovascular, neurodegenerative, respiratory, musculoskeletal, and renal diseases, but the opposite, that is, aggravation of various diseases, such as some cancers and neurodegenerative diseases, has also been reported. Accordingly, many natural and synthetic SIRT1 activators and inhibitors have been developed. Known SIRT1 activators of natural origin are mainly polyphenols. Nonetheless, various classes of non-polyphenolic monoterpenoids have been identified as inducers of SIRT1 expression and/or activity. This narrative review discusses current information on the evidence that supports the role of those compounds as SIRT1 activators and their potential both as tools for research and as pharmaceuticals for therapeutic application in age-related diseases.

Role of miRNAs in melanin metabolism: Implications in melanin-related diseases

BACKGROUND

MicroRNAs (miRNAs) are short single-stranded non-coding RNAs that regulate degradation and expression of messenger RNA (mRNA) and play a wide range of key roles in different biological processes. They mediate different stages of melanocyte differentiation, growth, and apoptosis through a variety of pathways and can mediate melanin production by targeting key enzymes.

AIMS

This article was aimed to review the role of miRNAs in melanin metabolism and to introduce the role and significance of miRNAs in melanin-related diseases.

MATERIALS & METHODS

Systematic search and retrospective review were performed on the published data.

RESULTS

This paper reviews the process of melanin synthesis and the regulatory mechanism, explores the miRNA expression profiles in different model organisms, and introduces the mechanisms of several key miRNAs participating in melanin metabolism through target genes. We also explore the potential role of miRNA as a new target for the treatment of melanin metabolism disease, including vitiligo, melanoma, and chloasma.

CONCLUSION

miRNAs play a key role in melanin-related diseases, and the miRNAs involved may be potential therapeutic targets.

Expression patterns of long non-coding RNAs in peripheral blood mononuclear cells of non-segmental vitiligo

OBJECTIVE

We explored the patterns of long non-coding RNA (lncRNA) expression in peripheral blood mononuclear cells (PBMCs) from patients with non-segmental vitiligo.

METHODS

We used high-throughput RNA sequencing technology to generate sequence data from five patients with non-segmental vitiligo alongside five normal healthy individuals, and then performed bioinformatics analyses to detect the differential expression of lncRNA in PBMCs. Gene Ontology (GO) and pathway analyses were performed for functional annotation, and quantitative real-time polymerase chain reaction (qRT-PCR) was used to verify gene expression. Target miRNAs and mRNAs of differentially expressed lncRNAs were predicted using bioinformatics analysis.

RESULTS

A total of 292 lncRNAs were differentially expressed in non-segmental vitiligo (fold change ≥ 2.0, P < .05), of which 171 were upregulated and 121 were downregulated. Six differentially expressed lncRNAs were selected, namely ENST00000460164.1, ENST00000393264.2, NR-046211.1, NR-135491.1, NR-135320.1, and ENST00000381108.3, for validation by qRT-PCR. The results showed that ENST00000460164.1 and NR-046211.1 were highly expressed in PBMCs of non-segmental vitiligo. An lncRNA-miRNA-mRNA network containing two lncRNAs, 17 miRNAs, and 223 mRNAs was constructed.

CONCLUSION

Our results revealed patterns of differentially expressed lncRNAs in the PBMCs of non-segmental vitiligo individuals. ENST00000460164.1, and NR-046211.1 may be potential biomarkers and drug targets for the treatment of non-segmental vitiligo.

LncRNA-mRNA co-expression network revealing the regulatory roles of lncRNAs in melanogenesis in vitiligo

Vitiligo is characterized by the progressive disappearance of melanocytes, resulting in depigmentation. Long noncoding RNAs (lncRNAs) are a class of noncoding RNAs that play an essential role in the regulation of inflammation and immunity. Published reports on the expression profile of lncRNAs in vitiligo cases and the potential biological function of lncRNAs in vitiligo are lacking. We performed RNA-Seq to identify the functions of lncRNAs in vitiligo. In total, 32 upregulated lncRNAs and 78 downregulated lncRNAs were identified in skin lesions with vitiligo. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis demonstrated that mRNAs regulated by abnormally expressed lncRNAs are most relevant to melanocyte function and melanogenesis. We identified 14 aberrantly expressed lncRNAs through the co-expression pattern that regulate the melanogenesis-related genes DCT, TYR, and TYRP1. Therefore, we speculate that these hub genes may be involved in pathological mechanisms in melanocytes in vitiligo. These genes are closely related to melanogenesis in vitiligo. Abnormally expressed lncRNAs directly or indirectly act on these target genes to regulate melanogenesis. Identifying lncRNAs and clarifying the regulatory roles of the lncRNA-mRNA network may be helpful to develop novel diagnoses or treatment targets for vitiligo.

Is there a relation between long non-coding RNA MALAT-1 and miRNA-9 in Egyptian patients with Vitiligo?

To conduct a clinical biochemical study that aids in investigation of some non-coding RNA expressions and polymorphisms (including long non-coding RNAs and miRNAs) namely, MALAT-1 and miR-9 in attempt to provide new diagnostic biomarkers in vitiligo patients for Egyptians. Twenty patients having vitiligo and other twenty apparently controls were included in this study. Serum and biopsy were taken where patients were classified into lesional and peri-lesional groups. Laboratory and pathological investigations were assessed. Serum miR-9 and long-non coding MALAT-1 were measured. Vitiligo patients had a mean age of 36.40±13.75. The mean serum miR-9 level in patients group (4.28 ± 1.70) was significantly higher than in the control (1.05 ± 0.12) (p = 0.001). The MALAT-1 level in vitiligo patients was (3.65 ± 1.30) significantly higher than control (1.45 ± 0.15) (p = 0.001). There was a positive association between the expression levels of MALAT-1and miR-9in serum and tissue as well where p-value <0.05. miR-9 as well as long non-coding MALAT-1 may be considered as biomarkers for vitiligo susceptibility which may provide a new direction for treatment.

Differential regulation of miR-21-5p delays wound healing of melanocyte-deprived vitiligo skin by modulating the expression of tumor-suppressors PDCD4 and Maspin

The loss of melanocytes in vitiligo is associated with architectural, transcriptional, and cellular perturbations of keratinocytes and manifests as a reduced proliferation potential in vitro and delayed re-epithelialization in vivo. To understand the molecular mechanisms underlying this delay, microRNA (miRNA) profiling was performed on split skin biopsies collected on Day 1 (basal level) and Day 14 (wound re-epithelialization) from nonlesional (NL) and lesional (L) skin of five subjects with stable nonsegmental vitiligo and 129 miRNAs were found to be differentially regulated between the NL and L healed epidermis. miR-21-5p, expressed at comparable levels on NL and L Day 1 samples, demonstrated significant upregulation during re-epithelialization. However, the extent of its upregulation was relatively lower in L (10 times compared to Day 1) as compared to NL skin (17 times compared to Day 1). The overexpression of miR-21 in keratinocytes led to a significant increase in the expression of proliferation markers (Ki67 and MCM6 messenger RNA, Ki67 positivity), along with an increase in keratinocyte migration. Using a small interfering RNA mediated knockdown approach, we further demonstrated that miR-21-5p mediates its effects by suppressing the expression of programmed cell death 4 (PDCD4) and mammary serine protease inhibitor (Maspin), both tumor-suppressor genes. Investigation of clinical samples corroborated the lower miR-21 levels and a higher expression of PDCD4 and Maspin in L Day 14 compared to the NL Day 14 epidermis. In conclusion, this study revealed that a relatively lower upregulation of miR-21-5p in L skin leads to significantly higher levels of PDCD4 and Maspin, delaying wound re-epithelialization by reducing the proliferation and migration of keratinocytes.

LncRNA-Malat1 promoting inflammatory response aggravates cerebral ischemia-reperfusion neuronal injury in rats by targeting miR-211-5p

BACKGROUND

Ischemic stroke is one kind of disorder of cerebral blood circulation, which poses a severe threaten to human health and quality of life, causing serious economic loss to families and society. LncRNA-Malat1(Metastasis-associated lung adenocarcinoma transcript 1) and miRNA-211-5p are abnormally expressed in stroke patients and in the middle cerebral ischemia-reperfusion injury (CIRI) model. However, the involvement between LncRNA-Malat1 and miR-211-5p in cerebral ischemia-reperfusion neuronal injury and its mechanism remain unclear.

METHODS

The middle cerebral ischemia-reperfusion injury (CIRI) model was established in rat, and the rat primary neuron injury model induced by oxygen-glucose deprivation/reoxygenation (OGD/R) was simulated in vitro. Level of LncRNA-Malat1, miR-211-5p and COX-2 mRNA were detected via RT-qPCR. The protein levels of COX-2, BAX and BCL-2 were measured by western blot. MTT assay was performed to detect cell viability.

RESULTS

In our study, LncRNA-Malat1 and COX-2 were up-regulated while miR-211-5p down-regulated in vitro and in vivo. Knockdown of LncRNA-Malat1 improved neurological deficit scores, reduced cerebral infarction volume in vivo, and significantly promoted cell viability, reduced apoptosis and proinflammatory factors PGE2 and IL-10 in vitro. More importantly, the level of miR-211-5p was negatively correlated with that of LncRNA-Malat1 and COX-2. Knockdown of LncRNA-Malat1 inhibited the expression of COX-2 by up-regulating miR-211-5p.

CONCLUSION

Higher expression of LncRNA-Malat1 was involved in neuronal injury, LncRNA-Malat1 knockdown may reduce inflammation and apoptosis by modulating miR-211-5p, which provided a new therapeutic strategy for clinical stroke intervention targets.

microRNAs in the Regulation of Melanogenesis

Melanogenesis is the process leading to the synthesis of melanin, the main substance that influences skin color and plays a pivotal role against UV damage. Altered melanogenesis is observed in several pigmentation disorders. Melanogenesis occurs in specialized cells called melanocytes, physically and functionally related by means of autocrine and paracrine interplay to other skin cell types. Several external and internal factors control melanin biosynthesis and operate through different intracellular signaling pathways, which finally leads to the regulation of microphthalmia-associated transcription factor (MITF), the key transcription factor involved in melanogenesis and the expression of the main melanogenic enzymes, including TYR, TYRP-1, and TYRP-2. Epigenetic factors, including microRNAs (miRNAs), are involved in melanogenesis regulation. miRNAs are small, single-stranded, non-coding RNAs, of approximately 22 nucleotides in length, which control cell behavior by regulating gene expression, mainly by binding the 3′ untranslated region (3′-UTR) of target mRNAs. This review collects data on the miRNAs involved in melanogenesis and how these miRNAs can modulate target gene expression. Bringing to light the biological function of miRNAs could lead to a wider understanding of epigenetic melanogenesis regulation and its dysregulation. This knowledge may constitute the basis for developing innovative treatment approaches for pigmentation dysregulation.

Integrated analysis of miRNA-mRNA networks reveals a strong anti-skin cancer signature in vitiligo epidermis

Expression of microRNAs (miRNAs) is often dysregulated in several cancers, including non-melanoma skin cancer (NMSC). Individuals with vitiligo possess a deregulated miRnome along with a lower risk of developing NMSCs. We used data sets from our previously published studies on vitiligo epidermis to construct functional miRNA-mRNA networks to understand the molecular basis underlying the lower incidence of NMSC observed in individuals with vitiligo. miRTarBase database was used to fetch the experimentally validated targets of differentially expressed miRNAs and two protein-protein interaction (PPI) networks were constructed for the miRNA-mRNA interactions (230 downregulated targets of 5 upregulated miRNAs and 47 upregulated mRNAs targeted by 12 downregulated miRNAs). Pathway enrichment analysis identified RNA biogenesis and transport as well as cell adhesion to be perturbed in vitiligo. Further, oncogenic transcription factors (OTFs) that were upregulated in publicly available squamous cell carcinoma (SCC) or basal cell carcinoma (BCC) microarray data were compared with that of vitiligo to decode skin cancer-specific molecular signatures. We identified three significantly upregulated miRNAs, miR-31-5p, miR-31-3p and miR-194-3p in lesional epidermis that could negatively regulate seven oncogenic transcription factors, FOXC1, AR, SP1, YY1, GLI2, TP53 and RARA, known to be over-expressed in SCC or BCC. Taken together, our study identified a perturbed miRNA-regulated transcriptome, which potentially confers protection to vitiligo skin from an increased incidence of NMSC.