Novel and founder variants of SERPINA12 in Chinese patients with autosomal recessive palmoplantar keratoderma.

1. We extend the spectrum of SERPINA12 variants in palmoplantar keratodermas. 2. The recurrent variant c.970_971del, mainly prevalent in the East Asia population, was proved to be a founder variant. 3. Considerable SERPINA12-related palmoplantar keratoderma patients could be identified from autosomal recessive, non-mutilating, diffused palmoplantar keratoderma patients. 4. Other serpin family members or their co-effect may participate in the etiologies of underexplored hereditary palmoplantar keratodermas.

GORAB promotes embryonic lung maturation through antagonizing AKT phosphorylation, versican expression, and mesenchymal cell migration.

Embryonic development of the alveolar sac of the lung is dependent upon multiple signaling pathways to coordinate cell growth, migration, and the formation of the extracellular matrix. Here, we identify GORAB as a regulator of embryonic alveolar sac formation as genetically disrupting the Gorab gene in mice resulted in fatal saccular maturation defects characterized by a thickened lung mesenchyme. This abnormality is not associated with impairments in cellular proliferation and death, but aberrantly increased protein kinase B (AKT) phosphorylation, elevated Vcan transcription, and enhanced migration of mesenchymal fibroblasts. Genetically augmenting PDGFRα, a potent activator of AKT in lung mesenchymal cells, recapitulated the alveolar phenotypes, whereas disrupting PDGFRα partially rescued alveolar phenotypes in Gorab-deficient mice. Overexpressing or suppressing Vcan in primary embryonic lung fibroblasts could, respectively, mimic or attenuate alveolar sac-like phenotypes in a co-culture model. These findings suggest a role of GORAB in negatively regulating AKT phosphorylation, the expression of Vcan, and the migration of lung mesenchyme fibroblasts, and suggest that alveolar sac formation resembles a patterning event that is orchestrated by molecular signaling and the extracellular matrix in the mesenchyme.

Clinicopathologic and trichoscopic features of keratosis follicularis spinulosa decalvans: A case series study.

Keratosis follicularis spinulosa decalvans (KFSD) is a rare X-linked hereditary disorder characterized by the triad of follicular hyperkeratosis-photophobia-alopecia. The clinical heterogeneity makes the diagnosis difficult. To investigate the clinicopathologic and trichoscopic features of KFSD and to further clarify the essential requisites for the diagnosis, we conducted a retrospective study of patients with KFSD. The clinical information, histologic features, and trichoscopic findings were evaluated. Eight patients were from seven separate families. Two females were mother and daughter from the same family and the other six patients were male and represented sporadic cases. The average age of onset of alopecia was 21.25 years. Involvement of the scalp hairs leading to progressive scarring alopecia on the midline of the scalp with variable degrees of inflammation was the pathognomonic feature. It typically began after puberty. Vellus hair-associated follicular hyperkeratosis affected all of the patients. However, photophobia was not a constant feature. Histopathologic examination revealed disorders of the hair follicle with an acute-chronic inflammatory response. Follicular changes including fused infundibulum, the protrusion of the outer root sheath into the follicular canal, and a dilatation of the follicles at the isthmus level caused by the occlusion of keratin were observed. The trichoscopic features included perifollicular scaling, tufted hairs, and loss of follicular openings. In conclusion, terminal hair involvement, either scalp hairs, eyebrows, or eyelashes, and the hyperkeratosis of the follicle of vellus hairs is the diagnostic basis of KFSD. We hypothesize that follicular changes in histopathology are the primary event that trigger variable inflammation and further follicular destruction.

TRPV3 facilitates lipolysis and attenuates diet-induced obesity via activation of the NRF2/FSP1 signaling axis.

Transient receptor potential vanilloid (TRPV) ion channels play a crucial role in various cellular functions by regulating intracellular Ca2+ levels and have been extensively studied in the context of several metabolic diseases. However, the regulatory effects of TRPV3 in obesity and lipolysis are not well understood. In this study, utilizing a TRPV3 gain-of-function mouse model (TRPV3G568V/G568V), we assessed the metabolic phenotype of both TRPV3G568V/G568V mice and their control littermates, which were randomly assigned to either a 12-week high-fat diet or a control diet. We investigated the potential mechanisms underlying the role of TRPV3 in restraining obesity and promoting lipolysis both in vivo and in vitro. Our findings indicate that a high-fat diet led to significant obesity, characterized by increased epididymal and inguinal white adipose tissue weight and higher fat mass. However, the gain-of-function mutation in TRPV3 appeared to counteract these adverse effects by enhancing lipolysis in visceral fat through the upregulation of the major lipolytic enzyme, adipocyte triglyceride lipase (ATGL). In vitro experiments using carvacrol, a TRPV3 agonist, demonstrated the promotion of lipolysis and antioxidation in 3T3-L1 adipocytes after TRPV3 activation. Notably, carvacrol failed to stimulate Ca2+ influx, lipolysis, and antioxidation in 3T3-L1 adipocytes treated with BAPTA-AM, a cell-permeable calcium chelator. Our results revealed that TRPV3 activation induced the action of transcriptional factor nuclear factor erythroid 2-related factor 2 (NRF2), resulting in increased expression of ferroptosis suppressor protein 1 (FSP1) and superoxide dismutase2 (SOD2). Moreover, the inhibition of NRF2 impeded carvacrol-induced lipolysis and antioxidation in 3T3-L1 adipocytes, with downregulation of ATGL, FSP1, and SOD2. In summary, our study suggests that TRPV3 promotes visceral fat lipolysis and inhibits diet-induced obesity through the activation of the NRF2/FSP1 signaling axis. We propose that TRPV3 may be a potential therapeutic target in the treatment of obesity.

TRPV3-Activated PARP1/AIFM1/MIF Axis through Oxidative Stress Contributes to Atopic Dermatitis.

TRPV3 is a temperature-sensitive calcium-permeable channel. In previous studies, we noticed prominent TUNEL-positive keratinocytes in patients with Olmsted syndrome and Trpv3+/G568V mice, both of which carry gain-of-function variants in the TRPV3 gene. However, it remains unclear how the keratinocytes die and whether this process contributes to more skin disorders. In this study, we showed that gain-of-function variant or pharmacological activation of TRPV3 resulted in poly(ADP-ribose) polymerase 1 (PARP1)/AIFM1/macrophage migration inhibitory factor axis-mediated parthanatos, which is an underestimated form of cell death in skin diseases. Chelating calcium, scavenging ROS, or inhibiting nitric oxide synthase effectively rescued the parthanatos, indicating that TRPV3 regulates parthanatos through calcium-mediated oxidative stress. Furthermore, inhibiting PARP1 downregulated TSLP and IL33 induced by TRPV3 activation in HaCaT cells, reduced immune cell infiltration, and ameliorated epidermal thickening in Trpv3+/G568V mice. Marked parthanatos was also detected in the skin of MC903-treated mice and patients with atopic dermatitis, whereas inhibiting PARP1 largely alleviated the MC903-induced dermatitis. In addition, stimulating parthanatos in mouse skin with methylnitronitrosoguanidine recapitulated many features of atopic dermatitis. These data demonstrate that the TRPV3-regulated parthanatos-associated PARP1/AIFM1/macrophage migration inhibitory factor axis is a critical contributor to the pathogenesis of Olmsted syndrome and atopic dermatitis, suggesting that modulating the PARP1/AIFM1/macrophage migration inhibitory factor axis is a promising therapy for these conditions.

SERPINB7 Deficiency Increases Legumain Activity and Impairs the Epidermal Barrier in Nagashima-Type Palmoplantar Keratoderma.

Nagashima-type palmoplantar keratoderma is an autosomal recessive genodermatosis caused by loss-of-function variants in SERPINB7 and is the most prevalent form of inherited palmoplantar keratodermas among Asians. However, there is currently no effective therapy for Nagashima-type palmoplantar keratoderma because its pathogenesis remains unclear. In this study, Serpinb7-/- mice were generated and spontaneously developed a disrupted skin barrier, which was further exacerbated by acetone-ether-water treatment. The skin of these Serpinb7-/- mice showed weakened cytoskeletal proteins. In addition, SERPINB7 deficiency consistently led to decreased epidermal differentiation in a 3-dimensional human epidermal model. We also demonstrated that SERPINB7 was an inhibitory serpin that mainly inhibited the protease legumain. SERPINB7 bound directly with legumain and inhibited legumain activity both in vitro and in vivo. Furthermore, we found that SERPINB7 inhibited legumain in a protease-substrate manner and identified the cleavage sites of SERPINB7 as Asn71 and Asn343. Overall, we found that SERPINB7 showed the nature of a cysteine protease inhibitor and identified legumain as a key target protease of SERPINB7. Loss of SERPINB7 function led to overactivation of legumain, which might disrupt cytoskeletal proteins, contributing to the impaired skin barrier in Nagashima-type palmoplantar keratoderma. These findings may lead to the development of therapeutic strategies for Nagashima-type palmoplantar keratoderma.

TRPV3 promotes sebocyte inflammation via transcriptional modulating TLR2 in acne.

Acne is a common chronic inflammatory disease of the pilosebaceous unit. Transient receptor potential vanilloid 3 (TRPV3) is an ion channel that is involved in inflammatory dermatosis development. However, the involvement of TRPV3 in acne-related inflammation remains unclear. Here, we used acne-like mice and human sebocytes to examine the role of TRPV3 in the development of acne. We found that TRPV3 expression increased in the skin lesions of Propionibacterium acnes (P. acnes)-injected acne-like mice and the facial sebaceous glands (SGs) of acne patients. TRPV3 promoted inflammatory cytokines and chemokines secretion in human sebocytes and led to neutrophil infiltration surrounding the SGs in acne lesions, further exacerbating sebaceous inflammation and participating in acne development. Mechanistically, TRPV3 enhanced TLR2 level by promoting transcriptional factor phosphorylated-FOS-like antigen-1 (p-FOSL1) expression and its binding to the TLR2 promoter, leading to TLR2 upregulation and downstream NF-κB signaling activation. Genetic or pharmacological inhibition of TRPV3 both alleviated acne-like skin inflammation in mice via the TLR2-NF-κB axis. Thus, our study revealed the critical role of TRPV3 in sebaceous inflammation and indicated its potential as an acne therapeutic target.

Transcriptome-based chemical screens identify CDK8 as a common barrier in multiple cell reprogramming systems.

Fibroblasts can be chemically induced to pluripotent stem cells (CiPSCs) through an extraembryonic endoderm (XEN)-like state or directly converted into other differentiated cell lineages. However, the mechanisms underlying chemically induced cell-fate reprogramming remain unclear. Here, a transcriptome-based screen of biologically active compounds uncovered that CDK8 inhibition was essential to enable chemically induced reprogramming from fibroblasts into XEN-like cells, then CiPSCs. RNA-sequencing analysis showed that CDK8 inhibition downregulated proinflammatory pathways that suppress chemical reprogramming and facilitated the induction of a multi-lineage priming state, indicating the establishment of plasticity in fibroblasts. CDK8 inhibition also resulted in a chromatin accessibility profile like that under initial chemical reprogramming. Moreover, CDK8 inhibition greatly promoted reprogramming of mouse fibroblasts into hepatocyte-like cells and induction of human fibroblasts into adipocytes. These collective findings thus highlight CDK8 as a general molecular barrier in multiple cell reprogramming processes, and as a common target for inducing plasticity and cell fate conversion.

PHDs-seq: a large-scale phenotypic screening method for drug discovery through parallel multi-readout quantification.

High-throughput phenotypic screening is a cornerstone of drug development and the main technical approach for stem cell research. However, simultaneous detection of activated core factors responsible for cell fate determination and accurate assessment of directional cell transition are difficult using conventional screening methods that focus on changes in only a few biomarkers. The PHDs-seq (Probe Hybridization based Drug screening by sequencing) platform was developed to evaluate compound function based on their transcriptional effects in a wide range of signature biomarkers. In this proof-of-concept demonstration, several sets of markers related to cell fate determination were profiled in adipocyte reprogramming from dermal fibroblasts. After validating the accuracy, sensitivity and reproducibility of PHDs-seq data in molecular and cellular assays, a panel of 128 signalling-related compounds was screened for the ability to induce reprogramming of keloid fibroblasts (KF) into adipocytes. Notably, the potent ATP-competitive VEGFR/PDGFR inhibitor compound, ABT869, was found to promote the transition from fibroblasts to adipocytes. This study highlights the power and accuracy of the PHDs-seq platform for high-throughput drug screening in stem cell research, and supports its use in basic explorations of the molecular mechanisms underlying disease development.

Excess KLHL24 Impairs Skin Wound Healing through the Degradation of Vimentin.

Start codon variants in ubiquitin ligase KLHL24 lead to a gain-of-function mutant KLHL24-ΔN28, which mediates the excessive degradation of keratin 15, desmin, and keratin 14, resulting in alopecia, cardiopathy, and epidermolysis bullosa syndrome. Patients with alopecia, cardiopathy, and epidermolysis bullosa syndrome normally present atrophic scars after wounds heal, which is rare in KRT14-related epidermolysis bullosa. The mechanisms underlying the formation of atrophic scars in epidermolysis bullosa of patients with alopecia, cardiopathy, and epidermolysis bullosa syndrome remain unclear. This study showed that KLHL24-ΔN28 impaired skin wound healing by excessively degrading vimentin. Heterozygous Klhl24c.3G>T knock-in mice displayed delayed wound healing and decreased wound collagen deposition. We identified vimentin as an unreported substrate of KLHL24. KLHL24-ΔN28 mediated the excessive degradation of vimentin, which failed to maintain efficient fibroblast proliferation and activation during wound healing. Furthermore, by mediating vimentin degradation, KLHL24 can hinder myofibroblast activation, which attenuated bleomycin-induced skin fibrosis. These findings showed the function of KLHL24 in regulating tissue remodeling, atrophic scarring, and fibrosis.

Investigation of Nagashima-type palmoplantar keratoderma in China: A cross-sectional study of 234 patients.

Nagashima-type palmoplantar keratoderma (NPPK) is the most prevalent hereditary palmoplantar keratoderma (PPK) in China, but there is a paucity of epidemiological data on the Chinese population. To explore the clinical and genetic characteristics, evaluate the demographic distribution, and estimate the burden of disease of NPPK. A total of 234 Chinese patients with NPPK were enrolled from two medical centers and an online PPK support group. Next-generation sequencing and Sanger sequencing were performed to screen out and confirm pathogenic mutations in SERPINB7. Clinical features and quality of life (QOL) were evaluated using self-completed questionnaires. In total, 14 pathogenic mutations were identified in SERPINB7 from the cohort. The top four recurrent mutations were c.796C>T (355, 75.9%), c.522dupT (66, 14.1%), c.650_653delCTGT (24, 5.1%), and c.455G>T (12, 2.6%), accounting for 97.6% of Chinese NPPK patients. Other mutations (11, 2.4%) include c.455-1G>T, c.336+2T>G, c.635delG and seven novel mutations c.2T>C, c.434delG, c.455-16A>G, c.656T>C, c.745-553T>G, c.832C>T, c.1036G>T. The estimated prevalence of NPPK in China was found to be 0.975/10 000 based on Chinese databases. Clinically, there were no apparent genotype-phenotype correlations in NPPK patients. Pediatric patients mainly presented with palmoplantar peeling, while adults presented with scale (p < 0.001). The most common comorbidities in NPPK patients were onychomycosis (40.0%), eczema (36.8%), and tinea pedis (30.3%). As for burden of disease, NPPK patients' QOL was decreased by a moderate degree. In this study, pathogenic mutations' allele frequencies in SERPINB7 were updated, and prevalence of NPPK in China was estimated. This large-scale cohort study provides evidence-based recommendations for patient management. Identification of new mutations are important for timely diagnosis of NPPK. Palmoplantar peeling in children can be used as a hallmark for early recognition of NPPK.

KLHL24-Mediated Hair Follicle Stem Cells Structural Disruption Causes Alopecia.

KLHL24 is an E3 ubiquitin ligase. Variants in the start codon of KLHL24 result in truncated KLHL24 protein lacking the initial 28 amino acids (KLHL24-ΔN28). KLHL24-ΔN28 is more stable than wild-type KLHL24 and causes excessive degradation of keratin 14, leading to epidermolysis bullosa. Patients with KLHL24-related epidermolysis bullosa usually develop alopecia, which is uncommon in patients with epidermolysis bullosa. The mechanisms by which KLHL24 variants cause alopecia is currently unclear. In this study, we show that KLHL24 regulates hair maintenance by mediating the stability of keratin 15. Using a Klhl24c.3G>T knock-in mouse model, we identify that KLHL24-ΔN28 disrupts the structure of hair follicle stem cells (HFSCs). Destructed HFSCs cannot anchor hairs and cause premature hair loss. Long-term destruction of HFSCs causes their exhaustion and hair follicle degeneration. Mechanically, KLHL24 mediates the ubiquitination and proteasomal degradation of keratin 15, an intermediate filament composing the HFSC cytoskeleton network. Keratin 15 is dramatically decreased in the skin of Klhl24c.3G>T mice and in patients with KLHL24-related epidermolysis bullosa. These findings show that KLHL24 plays a role in hair maintenance by regulating the cytoskeleton structure of HFSCs and highlight the importance of the ubiquitin‒proteasome system in the stability of HFSCs.

Tiamulin inhibits TNF-α and alleviates psoriasis-like dermatitis.

BACKGROUND: TNF-α elicits a cascade amplification effect in psoriasis. Macromolecule drugs targeting TNF-α are widely used for the clinical treatment of psoriasis. However, there are currently no effective small-molecule inhibitors that can be used in the clinic. OBJECTIVE: Novel TNF-α inhibitor was identified via high-throughput screening (HTS) and its anti-inflammatory activity was evaluated. METHODS: Two cell death models were established to identify inhibitors of TNF-α through HTS from a library of 3256 compounds. The effect of the inhibitor of TNF-α was tested by HaCaT cells in vitro and IMQ-induced psoriasis-like mouse model in vivo. RESULTS: Tiamulin fumarate (TF) was identified as an effective inhibitor of TNF-α. TF significantly blocked the NF-κB and MAPK signaling pathways in TNF-α-stimulated HaCaT cells. Additionally, systemic and topical administration of TF improved IMQ-induced psoriasis-like dermatitis in the mouse model. CONCLUSION: Our study established a HTS method to identify TF as an inhibitor of TNF-α. The protective roles of TF in psoriasis-related inflammation reveal the potential therapeutic value of TF for psoriasis.

Hair Loss Caused by Gain-of-Function Mutant TRPV3 Is Associated with Premature Differentiation of Follicular Keratinocytes.

Gain-of-function mutations in the TRPV3 gene can cause Olmsted syndrome characterized by palmoplantar and periorificial keratoderma, itch, and hair loss. The mechanism underlying the hair loss remains unclear. In this study, we engineered an Olmsted syndrome mouse model by introducing the point mutation G568V to the corresponding Trpv3 locus in the mice. These mice developed fully penetrant hair loss. The hair loss was associated with premature differentiation of follicular keratinocytes characterized by precocious degeneration of trichohyalin and keratins, increased production of deiminated proteins, elevated apoptosis, and attenuation of transcription regulators (Foxn1, Msx2, Dlx3, and Gata3) known to regulate hair follicle differentiation. These abnormalities occurred in the medial‒proximal region of the inner root sheath and the hair shaft, where Trpv3 is highly expressed, and correlated with an impaired formation of the hair canal and the hair shaft. The mutant Trpv3 mice also exhibited increased proliferation in the outer root sheath, accelerated hair cycle, reduction of hair follicle stem cells, and miniaturization of regenerated hair follicles. Findings from this study suggest that precocious maturation of postmitotic follicular keratinocytes drives hair loss in patients with Olmsted syndrome.

Overexpression of MYB in the Skin Induces Alopecia and Epidermal Hyperplasia.

Skin homeostasis is controlled by a complex interplay between tightly regulated transcription factors and signaling pathways. MYB is a transcription factor expressed in hair follicle progenitor cells and found overexpressed in adnexal skin tumors. However, the biological consequences of deregulated MYB expression in the skin remain poorly understood. To address this, we generated transgenic mice that overexpress MYB in epidermal and follicular keratinocytes. These mice exhibited a normal hair coat after birth but gradually developed alopecia, accompanied by altered follicular differentiation, disrupted hair cycle, and a marked depletion of hair follicle stem cells. Additionally, transgenic mice developed massive epidermal hyperplasia and hyperkeratosis. Global expression profiling not only confirmed that the skin of these mice exhibited transcriptomic features of alopecia and epidermal differentiation, but also revealed features of psoriasis and the inflammatory response. The latter was further confirmed by the increased T-cell infiltration found in the skin of transgenic mice. Overall, these results suggest that tight regulation of MYB expression in the skin is critical to maintain skin homeostasis.