LncRNA MEG3 suppresses PI3K/AKT/mTOR signalling pathway to enhance autophagy and inhibit inflammation in TNF-α-treated keratinocytes and psoriatic mice.

BACKGROUND: Psoriasis is a common chronic inflammatory skin disorder that causes patches of thick red skin and silvery scales and affects 1-3% of the population, which reduces patient's quality of life. Understanding the pathogenesis of psoriasis is crucial for developing novel therapeutic strategies. METHODS: HaCaT and NHEK cells were treated with TNF-α in vitro. A mouse model of psoriasis was established by topical imiquimod application on back skin. LncRNA MEG3 was cloned into the pcDNA3.1 vector and transfected in TNF-α-treated HaCaT and NHEK cells to overexpress its expression. Liposome-encapsulated pcDNA3.1-MEG3 was injected into imiquimod-treated mice via tail vein. RT-qPCR and western blot assays were used to examine the expression of lncRNA MEG3, IL-6, IL-8, IFN-γ, IL-1ß, LC3, Beclin 1, p62, p-p65, p65, NLRP3, p-PI3K, PI3K, p-AKT, AKT, p-mTOR, mTOR respectively. The secretion of IL-6, IL-8, IFN-γ and IL-1ß was determined using ELISA assay. Immunofluorescence and immunohistochemistry methods were performed for analyzing the expression of LC3 and NLRP3 in cells and skin tissues respectively. LY294002 was used to block the PI3K/AKT/mTOR signalling. MTT assay was applied to test the toxicity of LY294002 to HaCaT and NHEK cells. RESULTS: LncRNA MEG3 expression levels were downregulated in TNF-α-treated HaCaT and NHEK cells and skin tissues of psoriatic mice model. TNF-α treatment enhanced inflammation and suppressed autophagy in HaCaT and NHEK cells, which were largely reversed by overexpression of lncRNA MEG3. Autophagy puncta and NLRP3 inflammasome assembly showed the same patterns with the expression of inflammation and autophagy markers in TNF-α-treated HaCaT and NHEK cells with or without lncRNA MEG3 overexpression. TNF-α-induced activation of the PI3K/AKT/mTOR signalling was abolished by lncRNA MEG3 overexpression in HaCaT and NHEK cells. Blocking the PI3K/AKT/mTOR signalling inhibited TNF-α-induced inflammation and restored autophagy level in TNF-α-treated HaCaT and NHEK cells. Overexpression of lncRNA MEG3 suppressed inflammation, promoted autophagy and inhibited the activation of the PI3K/AKT/mTOR signalling in a mouse model of psoriasis. CONCLUSION: LncRNA MEG3 facilitates autophagy and suppresses inflammation in TNF-α-treated keratinocytes and psoriatic mice, which is dependent on the PI3K/AKT/mTOR signalling pathway. Our study enhances the understanding of psoriasis and provides potential therapeutic targets for psoriasis.

Loss-of-function mutations in HOXC13 cause pure hair and nail ectodermal dysplasia.

Pure hair and nail ectodermal dysplasia (PHNED) is a congenital condition characterized by hypotrichosis and nail dystrophy. Autosomal-recessive PHNED has previously been mapped to chromosomal region 12q12-q14.1, which contains the type II hair keratin and HOXC clusters. Hoxc13-null mice are known to develop hair and nail defects very similar to those seen in human PHNED. We performed whole-exome sequencing in a consanguineous Chinese family affected by PHNED and identified a homozygous nonsense mutation (c.390C>A [p.Tyr130(∗)]) in HOXC13 in all affected individuals. In an additional affected female from a consanguineous Afghan family, we found a 27.6 kb homozygous microdeletion involving the first exon of HOXC13. We examined HOXC13 expression in scalp specimen obtained from the index individual of the Chinese family and detected dramatically reduced mRNA levels in skin tissue and nearly absent protein staining in hair follicles, suggesting a mechanism of nonsense-mediated mRNA decay. We also observed markedly decreased expression of four HOXC13 target genes in the specimen. Taken together, our results demonstrate that loss-of-function mutations in HOXC13 cause autosomal-recessive PHNED and further highlight the importance of HOXC13 in hair and nail development.

The role of PAR2 in regulating MIF release in house dust mite-induced atopic dermatitis.

Atopic dermatitis (AD) is a chronic disease characterized by relapsed eczema and intractable itch, and is often triggered by house dust mites (HDM). PAR2 is a G-protein coupled receptor on keratinocytes and may be activated by HDM to affect AD processes. We first established a HDM-derived AD mouse model in wild-type (WT) and Par2-/- mice. Single cell RNA sequencing of the diseased skins found a stronger cellular communication between the ligand macrophage migration inhibitory factor (MIF) from keratinocytes and its receptors on antigen-presenting cells, suggesting the critical role of MIF in AD. HDM-WT mice showed severer skin lesions and pathological changes with stronger immunofluorescence MIF signals in skin sections than HDM-Par2-/- mice. Primary keratinocytes from WT mice stimulated with HDM or SLIGRL (PAR2 agonist) secreted more MIF in cultured medium and induced stronger immunofluorescence MIF signals than those from Par2-/- mice. The skin section of HDM-WT mice showed higher immunofluorescence signals of P115 (relating to MIF secretion) and KIF13B (possibly relating to intracellular trafficking of MIF) than that of HDM-Par2-/- mice. Acetylation of α-tubulin increased after stimulation by SLIGRL in WT keratinocytes but not in Par2-/- keratinocytes. HDM-WT mice treated with the MIF antagonist ISO-1 displayed improvement of AD-like presentations and lower expressions of IL-4, IL-13, TSLP and Arg1 (a biomarker of M2 macrophage) mRNAs. We conclude that MIF is an important cytokine and is significantly increased in the AD model. PAR2 affects AD changes by regulating the expression, intracellular trafficking, and secretion of MIF in epidermis.

Novel pathogenic variants in the RECQL4 gene causing Rothmund-Thomson syndrome in three Chinese patients.

Rothmund-Thomson syndrome (RTS) is a rare autosomal-recessive disorder characterized by poikiloderma, short stature, sparse hair, skeletal abnormalities, and cancer predisposition. Mutations in ANAPC1 or RECQL4 have been identified to underlie RTS. Either Sanger sequencing or next-generation sequencing (NGS) was performed for three Chinese RTS patients. Copy number variants were called by the eXome-Hidden Markov Model using read-depth data of NGS, and the putative heterozygous deletion was confirmed by PCR with multiple primers. The breakpoints were identified by Sanger sequencing. All patients presented with characteristic features of poikiloderma, short stature, and sparse hair, eyelashes, and eyebrows. In addition, patient 1 had intellectual disability and speech delay, and patient 2 developed osteosarcoma when she was 13 years old. Biallelic RECQL4 variants were identified in all three patients. Five of the six variants were novel, including c.119-1G>A, c.2886-1G>A, c.2290C>T (p.Gln764*), and c.3552dupG (p.Arg1185Glufs*42), and a gross deletion encompassing exons 6 to 10. Our study expands the genetic and clinical spectrums of RTS. Furthermore, we reported the first heterozygous gross deletion in RECQL4.

The Polygenic Map of Keloid Fibroblasts Reveals Fibrosis-Associated Gene Alterations in Inflammation and Immune Responses.

Due to many inconsistencies in differentially expressed genes (DEGs) related to genomic expression changes during keloid formation and a lack of satisfactory prevention and treatment methods for this disease, the critical biomarkers related to inflammation and the immune response affecting keloid formation should be systematically clarified. Normal skin/keloid scar tissue-derived fibroblast genome expression data sets were obtained from the Gene Expression Omnibus (GEO) and ArrayExpress databases. Hub genes have a high degree of connectivity and gene function aggregation in the integration network. The hub DEGs were screened by gene-related protein-protein interactions (PPIs), and their biological processes and signaling pathways were annotated to identify critical biomarkers. Finally, eighty-one hub DEGs were selected for further analysis, and some noteworthy signaling pathways and genes were found to be closely related to keloid fibrosis. For example, IL17RA is involved in IL-17 signal transduction, TIMP2 and MMP14 activate extracellular matrix metalloproteinases, and TNC, ITGB2, and ITGA4 interact with cell surface integrins. Furthermore, changes in local immune cell activity in keloid tissue were detected by DEG expression, immune cell infiltration, and mass CyTOF analyses. The results showed that CD4+ T cells, CD8+ T cells and NK cells were abnormal in keloid tissue compared with normal skin tissue. These findings not only support the key roles of fibrosis-related pathways, immune cells and critical genes in the pathogenesis of keloids but also expand our understanding of targets that may be useful for the treatment of fibrotic diseases.

Ichthyosis with confetti caused by new and recurrent mutations in KRT10 associated with varying degrees of keratin 10 mis-localization.

BACKGROUND: Ichthyosis with confetti (IWC) is an extremely rare autosomal-dominant genodermatosis characterized by erythroderma with numerous confetti-like pale spots. IWC is caused by mutations in KRT10 (IWC-I) or KRT1 (IWC-II) which affect their tail domains. In IWC-I, the mutations lead to replacement of glycine/serine-rich keratin 10 (K10) tail with arginine- or alanine-rich frameshift motifs, causing K10 mis-localization which might trigger loss of the mutant KRT10 allele via mitotic recombination, leading to genetic reversion. OBJECTIVE: To investigate mutations in five IWC-I patients and their functional consequences. METHODS: We performed Sanger sequencing of KRT1 and KRT10 in peripheral blood samples of five patients, with highly polymorphic KRT10 SNPs genotyped to confirm loss-of-heterozygosity in the epidermis of pale spots. K10 expression pattern was examined in both patient skin biopsies and HaCaT cells overexpressing mutant KRT10-enhanced green fluorescence protein fusion. RESULTS: Four novel and one recurrent KRT10 mutations were identified in patient peripheral blood samples but not in the corresponding pale spot epidermis. Two of the mutations, c.1696_1699dupCACA and c.1676dupG, affected residues close to K10 carboxyl terminus and encoded only 3 and 6 arginine residues, which were far fewer than reported previously. Interestingly, imaging analyses for K10 in HaCaT cells overexpressing either of these two mutations and in the corresponding patients' affected skin, showed a remarkably lower level of K10 mis-localization compared to that of other mutations reported in this study. CONCLUSIONS: Our findings suggest that the number of arginine residues in the mutant tail may correlate with the level of K10 mis-localization in IWC-I keratinocytes. These results expand the genotypic and phenotypic spectrum of IWC-I.

LncRNA MEG3 influences the proliferation and apoptosis of psoriasis epidermal cells by targeting miR-21/caspase-8.

BACKGROUND: It was reported that microRNA-21(miR-21) was differentially expressed in the keratinocytes of psoriasis patients, and it may influence the apoptosis and proliferation of cells. The role of lncRNA maternally expressed gene3 (MEG3), a competing endogenous RNAs of miR-21, in the progression of psoriasis remains unclear. We aimed to unfold the influence of MEG3 and miR-21 on the proliferation and apoptosis of psoriasis epidermal cells. METHODS: 50µg/L TNF-α was used to treat HaCaTs and NHEKs cells for 24 h, and then different experiments were conducted. qRT-PCR were applied for measuring the mRNA level of MEG3, miR-2, and caspase-8, and the protein expression of caspase-8 was measured with western blotting. Flow cytometry was used for assessing apoptosis. Cell proliferation was detected using MTT and colony formation assays. Dual luciferase reporter assay was applied for confirming the binding site between MEG3 and miR-21, miR-21 and Caspase-8. RESULTS: A cell model for in vitro studying the role of MEG3 in psoriasis pathophysiology was established using HaCaT and HHEKs. MEG3 was significantly down-regulated in HaCaT, HHEKs, and psoriatic skin samples. MEG3 inhibits proliferation and promotes apoptosis of Activated-HaCaT (Act-HaCaT) and Activated-HHEKs (Act- HHEK) by regulating miR-21, and the binding site between MEG3 and miR-21 was identified. We also found that miR-21 could inhibit the level of caspase-8 and identified the binding site between caspase-8 and miR-21. Some down-stream proteins of caspase-8, Cleaved caspase-8, cytc, and apaf-1 were regulated by miR-21 and MEG3. CONCLUSION: MEG3/miR-21 axis may regulate the expression of caspase-8, and further influence the proliferation and apoptosis of psoriasis keratinocyte, Act-HaCaT and Act- HHEK. Therefore, our findings may provide a new thought for the study of pathogenesis and treatment of psoriasis.

Exome sequencing reveals novel BCS1L mutations in siblings with hearing loss and hypotrichosis.

As a powerful tool to identify the molecular pathogenesis of Mendelian disorders, exome sequencing was used to identify the genetic basis of two siblings with hearing loss and hypotrichosis and clarify the diagnosis. No pathogenic mutations in GJB2, GJB3 and GJB6 genes were found in the siblings. By analysis of exome of the proband, we identified a novel missense (p.R306C) mutation and a nonsense (p.R186*) mutation in the BCS1L gene. Mutations were confirmed by Sanger sequencing. The siblings were compound heterozygotes, and the inheritance mode of autosomal recessive was postulated. BCS1L is the causative gene of Björnstad syndrome, which is characterized by sensorineural hearing loss and pili torti. The longitudinal gutters along the hair shaft were found by scanning electron microscopy in our patient. Therefore the diagnosis of Björnstad syndrome was eventually made for the patients. Our study extends the phenotypic spectrum of Björnstad syndrome and highlights the clinical applicability of exome sequencing as a diagnostic tool for atypical Mendelian disorders.