Hailey-Hailey disease is caused by mutations in ATP2C1 encoding a novel Ca(2+) pump

Acute generalized exanthematous pustulosis associated with clindamycin in a patient with Hailey-Hailey disease

A 61-year-old African-American female with moderately controlled Hailey-Hailey disease (HHD) presents to the emergency department with a rash and fever. One day prior to her presentation, she was started on oral clindamycin for a tooth extraction procedure. Her physical examination shows diffuse erythema on the trunk and extremities with multiple nonfollicular pustules. A punch biopsy of her upper extremity revealed intraepidermal acantholysis, neutrophilic spongiosis, and subcorneal pustules. The perivascular and interstitial superficial dermal infiltrate is mixed and composed of predominantly neutrophils, with lymphocytes and rare eosinophils. These findings suggest a superimposed acute generalized exanthematous pustulosis (AGEP) in the background of HHD. AGEP is a potentially severe cutaneous condition characterized by the abrupt onset of numerous nonfollicular pustules in a background of pruritic edematous erythroderma. To date, only two case reports have described AGEP in patients with HHD. Early diagnosis of AGEP is essential to initiate prompt and aggressive systemic therapy, prompt medication cessation, close monitoring for end-organ damage, and improve overall morbidity and mortality.

Transcriptional profiling of rare acantholytic disorders suggests common mechanisms of pathogenesis

Darier, Hailey-Hailey, and Grover diseases are rare acantholytic skin diseases. While these diseases have different underlying causes, they share defects in cell-cell adhesion in the epidermis and desmosome organization. To better understand the underlying mechanisms leading to disease in these conditions, we performed RNA-seq on lesional skin samples from patients. The transcriptomic profiles of Darier, Hailey-Hailey, and Grover diseases were found to share a remarkable overlap, which did not extend to other common inflammatory skin diseases. Analysis of enriched pathways showed a shared increase in keratinocyte differentiation, and a decrease in cell adhesion and actin organization pathways in Darier, Hailey-Hailey, and Grover diseases. Direct comparison to atopic dermatitis and psoriasis showed that the downregulation in actin organization pathways was a unique feature in the acantholytic skin diseases. Furthermore, upstream regulator analysis suggested that a decrease in SRF/MRTF activity was responsible for the downregulation of actin organization pathways. Staining for MRTFA in lesional skin samples showed a decrease in nuclear MRTFA in patient skin compared with normal skin. These findings highlight the significant level of similarity in the transcriptome of Darier, Hailey-Hailey, and Grover diseases, and identify decreases in actin organization pathways as a unique signature present in these conditions.

Insights into the regulation of cellular Mn2+ homeostasis via TMEM165

Golgi cation homeostasis is known to be crucial for many cellular processes including vesicular fusion events, protein secretion, as well as for the activity of Golgi glycosyltransferases and glycosidases. TMEM165 was identified in 2012 as the first cation transporter related to human glycosylation diseases, namely the Congenital Disorders of Glycosylation (CDG). Interestingly, divalent manganese (Mn) supplementation has been shown to suppress the observed glycosylation defects in TMEM165-deficient cell lines, thus suggesting that TMEM165 is involved in cellular Mn homeostasis. This paper demonstrates that the origin of the Golgi glycosylation defects arises from impaired Golgi Mn homeostasis in TMEM165-depleted cells. We show that Mn supplementation fully rescues the Mn content in the secretory pathway/organelles of TMEM165-depleted cells and hence the glycosylation process. Strong cytosolic and organellar Mn accumulations can also be observed in TMEM165- and SPCA1-depleted cells upon incubation with increasing Mn concentrations, thus demonstrating the crucial involvement of these two proteins in cellular Mn homeostasis. Interestingly, our results show that the cellular Mn homeostasis maintenance in control cells is correlated with the presence of TMEM165 and that the Mn-detoxifying capacities of cells, through the activity of SPCA1, rely on the Mn-induced degradation mechanism of TMEM165. Finally, this paper highlights that TMEM165 is essential in secretory pathway/organelles Mn homeostasis maintenance to ensure both Golgi glycosylation enzyme activities and cytosolic Mn detoxification.

Structure and transport mechanism of the human calcium pump SPCA1

Secretory-pathway Ca2+-ATPases (SPCAs) play critical roles in maintaining Ca2+ homeostasis, but the exact mechanism of SPCAs-mediated Ca2+ transport remains unclear. Here, we determined six cryo-electron microscopy (cryo-EM) structures of human SPCA1 (hSPCA1) in a series of intermediate states, revealing a near-complete conformational cycle. With the aid of molecular dynamics simulations, these structures offer a clear structural basis for Ca2+ entry and release in hSPCA1. We found that hSPCA1 undergoes unique conformational changes during ATP binding and phosphorylation compared to other well-studied P-type II ATPases. In addition, we observed a conformational distortion of the Ca2+-binding site induced by the separation of transmembrane helices 4L and 6, unveiling a distinct Ca2+ release mechanism. Particularly, we determined a structure of the long-sought CaE2P state of P-type IIA ATPases, providing valuable insights into the Ca2+ transport cycle. Together, these findings enhance our understanding of Ca2+ transport by hSPCA1 and broaden our knowledge of P-type ATPases.

Manganese Stress Tolerance Depends on Yap1 and Stress-Activated MAP Kinases

Understanding which intracellular signaling pathways are activated by manganese stress is crucial to decipher how metal overload compromise cellular integrity. Here, we unveil a role for oxidative and cell wall stress signaling in the response to manganese stress in yeast. We find that the oxidative stress transcription factor Yap1 protects cells against manganese toxicity. Conversely, extracellular manganese addition causes a rapid decay in Yap1 protein levels. In addition, manganese stress activates the MAPKs Hog1 and Slt2 (Mpk1) and leads to an up-regulation of the Slt2 downstream transcription factor target Rlm1. Importantly, Yap1 and Slt2 are both required to protect cells from oxidative stress in mutants impaired in manganese detoxification. Under such circumstances, Slt2 activation is enhanced upon Yap1 depletion suggesting an interplay between different stress signaling nodes to optimize cellular stress responses and manganese tolerance.

Sequential treatments of Hailey-Hailey disease with photodynamic therapy, botulinum toxin type A and dapsone: A case report

Hailey-Hailey disease is a rare autosomal dominant chronic recalcitrant blistering genodermatosis involving the intertriginous areas. Therapeutic options are various, depending on the type and size of the lesion, and include topical and systemic corticosteroids, topical and systemic retinoids, and DMARDs, but the only true curative approach is represented by the destruction of the affected areas through different techniques like carbon dioxide laser, photodynamic therapy, electron beam radiotherapy, botulinum toxin type A. We report a case of Hailey-Hailey disease successfully treated with a consequential regimen of PDT, botulinum toxin type A and dapsone.

Subcellular compartmentalization of STIM1 for the distinction of Darier disease from Hailey-Hailey disease

BACKGROUND AND OBJECTIVES

Darier disease (DD) and Hailey-Hailey disease (HHD) are rare disorders caused by mutations in the ATPase, Sarcoplasmic/Endoplasmic Reticulum Ca²⁺ Transporting 2 (ATP2A2) and ATPase Ca²⁺ Transporting Type 2C, Member 1 (ATP2C1) gene, respectively, which lead to a disturbance of calcium metabolism in keratinocytes. Clinically, this is reflected by an impairment of keratinization. Histologically, acantholysis with variable degrees of dyskeratosis and parakeratosis is observed. Both diseases can usually be differentiated clinically, histopathologically and genetically. However, their routine distinction might be challenging since some patients do not harbor ATP2A2 or ATP2C1 mutations. To solve this diagnostic challenge, we studied the differential expression of two proteins of store-operated calcium entry (SOCE), stromal interaction molecule 1 (STIM1) and calcium release-activated calcium modulator 1 (ORAI1), by immunohistochemistry.

PATIENTS AND METHODS

Five individuals with ambiguous diagnostic findings and eight controls with an unambiguous diagnosis were studied clinically, histologically, genetically, and by immunohistochemistry for STIM1 and ORAI1.

RESULTS

DD patients consistently showed a cytoplasmic STIM1 expression while patients with HHD revealed a membrane-associated staining pattern. In contrast, ORAI1 did not show a differential expression pattern.

CONCLUSIONS

Our data suggest subcellular compartmentalization of STIM1 as novel biomarker for the distinction of the two disorders.

The Pathogenic Mechanism of the ATP2C1 p.Ala109_Gln120del Mutation in Hailey-Hailey Disease

Background

Hailey-Hailey disease (HHD) is an autosomal dominant cutaneous disorder that manifests as repeated blisters and erosions on flexural or intertriginous skin areas. The calcium-transporting ATPase type 2C member 1 gene (ATP2C1) encodes the secretory pathway Ca²⁺/Mn²⁺-ATPase 1 (SPCA1), whose deficiency is responsible for HHD. An ATP2C1 splice-site mutation (c.325-2A>G, p.Ala109_Gln120del) was previously identified in a Han Chinese family with HHD.

Methods

In this study, the identified ATP2C1 splice-site mutation (c.325-2A>G, p.Ala109_Gln120del) was investigated in transfected human embryonic kidney 293 cells to analyze its pathogenic mechanism in HHD patients by using cycloheximide chase assay, CCK8 assay and in silico modeling of SPCA1 mutant.

Results

Cycloheximide chase assay showed that the degradation rate of the SPCA1 mutant was not obviously faster than that of the normal SPCA1. CCK8 assay showed that cell proliferation rates in the wild-type, A109_Q120del, and empty vector control groups all decreased in the gradient Mn²⁺ solutions in a dose-dependent manner. The cell proliferation rate in the wild-type was lower than that in the A109_Q120del and empty vector control (both P < 0.01), indicating overexpression of normal SPCA1 may rather induce Golgi stress, and even cell death. The cell proliferation rate in the A109_Q120del was lower than that in the empty vector control (P < 0.01), indicating that overexpression of the mutated SPCA1 may decrease its detoxification capability. Three-dimensional (3D) structure model of SPCA1 built by SWISS-MODEL and PyMOL showed that absence of the 12 amino acids from p.Ala109 to p.Gln120 in the SPCA1 mutant can cause obviously shortened transmembrane 2, which may affect correct localization of SPCA1 on the Golgi.

Conclusion

These results demonstrate that the ATP2C1 mutation (c.325-2A>G, p.Ala109_Gln120del) may cause impaired SPCA1 capability to detoxify Mn²⁺ and abnormal SPCA1 structure, which reveals a new side for the pathogenesis of HHD.

Golgi-localized calcium/manganese transporters FgGdt1 and FgPmr1 regulate fungal development and virulence by maintaining Ca2+ and Mn2+ homeostasis in Fusarium graminearum

Calcium and manganese transporters play important roles in regulating Ca²⁺ and Mn²⁺ homeostasis in cells, which is necessary for the normal physiological activities of eukaryotes. Gdt1 and Pmr1 function as calcium/manganese transporters in the Golgi apparatus. However, the functions of Gdt1 and Pmr1 have not been previously characterized in the plant pathogenic fungus Fusarium graminearum. Here, we identified and characterized the biological functions of FgGdt1 and FgPmr1 in F. graminearum. Our study shows that FgGdt1 and FgPmr1 are both localized to the cis- and medial-Golgi. Disruption of FgGdt1 or FgPmr1 in F. graminearum caused serious defects in vegetative growth, conidiation, sexual development and significantly decreased virulence in wheat but increased deoxynivalenol (DON) production. Importantly, FgGdt1 is involved in Ca²⁺ and Mn²⁺ homeostasis and the severe phenotypic defects of the ΔFggdt1 mutant were largely due to loss of FgGdt1 function in Mn²⁺ transportation. FgGdt1-mCherry colocalizes with FgPmr1-GFP at the Golgi, and FgGDT1 exerts its biological function upstream of FgPMR1. Taken together, our results collectively demonstrate that the cis- and medial-Golgi-localized proteins FgGdt1 and FgPmr1 regulate Ca²⁺ and Mn²⁺ homeostasis of the Golgi apparatus, and this function is important in modulating the growth, development, DON biosynthesis and pathogenicity of F. graminearum.

The role of metal ions in the Golgi apparatus

The Golgi apparatus is a membrane-bound organelle that functions as a central role in the secretory pathway. Since the discovery of the Golgi apparatus, its structure and function have attracted ever-increasing attention from researchers. Recently, it has been demonstrated that metal ions are necessary for the Golgi apparatus to maintain its proper structure and functions. Given that metal ions play an important role in various biological processes, their abnormal homeostasis is related to many diseases. Therefore, in this paper, we reviewed the uptake and release mechanisms of the Golgi apparatus Ca²⁺ , Cu, and Zn²⁺ . Furthermore, we describe the diseases associated with Golgi apparatus Ca²⁺ , Cu, and Zn²⁺ imbalance.

Inhibition of the human secretory pathway Ca2+, Mn2+-ATPase1a by 1,3-thiazole derivatives

The human Golgi/secretory pathway Ca²⁺,Mn²⁺-ATPase 1 (hSPCA1) transports Ca²⁺ and Mn²⁺ into the Golgi lumen. Studies of the biological functions of hSPCA1 are limited by a lack of selective pharmacological tools for SPCA1 inhibition. The aim of this study was therefore to identify compounds that specifically inhibit hSPCA1 activity. We found that five 1,3-thiazole derivatives exhibited inhibitory action towards the ATP hydrolysis activity of hSPCA1a in a concentration-dependent manner. Among the derivatives tested, compound 1 was the most potent, completely inhibiting hSPCA1a activity with a half-maximal inhibition (IC₅₀) value of 0.8 μM. Compound 1 also partially inhibited the activity of another Ca²⁺,Mn²⁺-ATPase (hSPCA2) and Ca²⁺-ATPase (rSERCA1a), but had no effect on Na⁺,K⁺-ATPase or H⁺,K⁺-ATPase. Treatment of HeLa cells with compound 1 led to fragmentation of the Golgi ribbon into smaller stacks. In addition, compound 1 mobilized intracellular Ca²⁺ in HeLa cells that had been pre-treated with thapsigargin. Therefore, based on its selectivity and potency, compound 1 may be a valuable tool with which to further explore the role of SPCA1 in cellular processes.

Two novel mutations in the ATP2C1 gene found in Japanese patients with Hailey-Hailey disease

Hailey-Hailey disease (HHD) is an autosomal dominant genodermatosis and the defective gene in HHD is ATP2C1, which encodes secretory pathway Ca²⁺ /Mn²⁺ ATPase type 1 (SPCA1). Here we report four Japanese HHD patients showing three kinds of mutations with premature termination codons in the ATP2C1 gene, including two novel ones. Patient 1 was a 39-year-old man with a novel heterozygous mutation, c.664dup in exon 8 (p.N215Kfs*26). Patient 2 was a 33-year-old man (the younger brother of patient 1) with the same mutation as patient 1. Patient 3 was a 55-year-old man with a previously reported heterozygous mutation, c.519dup in exon 7 (p.R174Tfs*4). Patient 4 was a 33-year-old woman with a novel heterozygous mutation, c.2640del in exon 27 (p.L881Ffs*10). The clinical characteristics of our four cases varied in disease severity and the response to treatment. The present cases enrich the database of mutational analysis for HHD.

Golgi Metal Ion Homeostasis in Human Health and Diseases

The Golgi apparatus is a membrane organelle located in the center of the protein processing and trafficking pathway. It consists of sub-compartments with distinct biochemical compositions and functions. Main functions of the Golgi, including membrane trafficking, protein glycosylation, and sorting, require a well-maintained stable microenvironment in the sub-compartments of the Golgi, along with metal ion homeostasis. Metal ions, such as Ca²⁺, Mn²⁺, Zn²⁺, and Cu²⁺, are important cofactors of many Golgi resident glycosylation enzymes. The homeostasis of metal ions in the secretory pathway, which is required for proper function and stress response of the Golgi, is tightly regulated and maintained by transporters. Mutations in the transporters cause human diseases. Here we provide a review specifically focusing on the transporters that maintain Golgi metal ion homeostasis under physiological conditions and their alterations in diseases.

Case Report: A Case of Hailey-Hailey Disease Mimicking Condyloma Acuminatum and a Novel Splice-Site Mutation of ATP2C1 Gene

Hailey–Hailey disease (HHD) is a rare autosomal-dominant blistering disorder characterized by recurrent vesicular and erosive lesions at intertriginous sites. We described a 24-year-old male who presented with multiple bright red verrucous papules in his mons pubis, bilateral groins, scrotum, perineum, and crissum, clinically resembling condyloma acuminatum. The histopathology showed extensive acantholysis with the characteristic appearance of a dilapidated brick-wall. The mutation analysis revealed a novel splice-site mutation in the ATP2C1 gene. The patient was definitely diagnosed with HHD. The antibacterial treatments resulted in a dramatic improvement. Our findings help to broaden the understanding of clinical manifestations of HHD and improve the clinical diagnosis and treatment of this disease.

Darier and Hailey-Hailey disease: update 2021

The autosomal-dominant genodermatoses Darier disease and Hailey-Hailey disease present special challenges to dermatologists. Despite their similar pathogenesis featuring impaired adhesion of suprabasal keratinocytes as a result of defective ATPases in epidermal calcium channels, the two diseases differ considerably in clinical presentation and therapeutic options. Darier disease is characterized by reddish brown, keratotic papules in seborrheic and intertriginous areas, which may coalesce into extensive lesions. Individuals affected with Hailey-Hailey disease primarily develop intertriginous papulovesicles and small blisters, which often evolve into erythematous plaques with erosions and painful fissures. Quality of life is significantly reduced because of complaints (itch, burning sensation, pain), body malodor and chronicity. Therapeutic options remain limited. Antiseptics and intermittent topical corticosteroids are a cornerstone of therapy, and systemic anti-infective treatment is often required in cases of superinfection. Ablative surgical interventions such as dermabrasion and CO₂ laser surgery can lead to long-term remissions in intertriginous Hailey-Hailey disease, while temporary relief may also be achieved by intralesional injections of botulinum toxin. Of the systemic medications available for Darier disease, acitretin, which is approved for this purpose, has the best supporting evidence. The efficacy of immunosuppressants and immune modulators is inconsistent. Low-dose naltrexone produces more satisfactory results in Hailey-Hailey than Darier disease. The present CME article summarizes current knowledge of the two dermatoses, taking recent developments into account.

Regional Differences in the Permeability Barrier of the Skin-Implications in Acantholytic Skin Diseases

The chemical milieu, microbiota composition, and immune activity show prominent differences in distinct healthy skin areas. The objective of the current study was to compare the major permeability barrier components (stratum corneum and tight junction (TJ)), investigate the distribution of (corneo)desmosomes and TJs, and measure barrier function in healthy sebaceous gland-rich (SGR), apocrine gland-rich (AGR), and gland-poor (GP) skin regions. Molecules involved in cornified envelope (CE) formation, desquamation, and (corneo)desmosome and TJ organization were investigated at the mRNA and protein levels using qRT-PCR and immunohistochemistry. The distribution of junction structures was visualized using confocal microscopy. Transepidermal water loss (TEWL) functional measurements were also performed. CE intracellular structural components were similarly expressed in gland-rich (SGR and AGR) and GP areas. In contrast, significantly lower extracellular protein levels of (corneo)desmosomes (DSG1 and CDSN) and TJs (OCLN and CLDN1) were detected in SGR/AGR areas compared to GP areas. In parallel, kallikrein proteases were significantly higher in gland-rich regions. Moreover, gland-rich areas were characterized by prominently disorganized junction structures ((corneo)desmosomes and TJs) and significantly higher TEWL levels compared to GP skin, which exhibited a regular distribution of junction structures. According to our findings, the permeability barrier of our skin is not uniform. Gland-rich areas are characterized by weaker permeability barrier features compared with GP regions. These findings have important clinical relevance and may explain the preferred localization of acantholytic skin diseases on gland-rich skin regions (e.g., Pemphigus foliaceus, Darier's disease, and Hailey-Hailey disease).

Epidermal Lamellar Body Biogenesis: Insight Into the Roles of Golgi and Lysosomes

Epidermal lamellar bodies (eLBs) are secretory organelles that carry a wide variety of secretory cargo required for skin homeostasis. eLBs belong to the class of lysosome-related organelles (LROs), which are cell-type-specific organelles that perform diverse functions. The formation of eLBs is thought to be related to that of other LROs, which are formed either through the gradual maturation of Golgi/endosomal precursors or by the conversion of conventional lysosomes. Current evidence suggests that eLB biogenesis presumably initiate from trans-Golgi network and receive cargo from endosomes, and also acquire lysosome characteristics during maturation. These multistep biogenesis processes are frequently disrupted in human skin disorders. However, many gaps remain in our understanding of eLB biogenesis and their relationship to skin diseases. Here, we describe our current understanding on eLB biogenesis with a focus on cargo transport to this LRO and highlight key areas where future research is needed.

Role of Calcium/Calcineurin Signalling in Regulating Intracellular Reactive Oxygen Species Homeostasis in Saccharomyces cerevisiae

The calcium/calcineurin signalling pathway is required for cell survival under various environmental stresses. Using Saccharomyces cerevisiae, we explored the mechanism underlying calcium-regulated homeostasis of intracellular reactive oxygen species (ROS). We found that deletion of acyltransferase Akr1 and C-5 sterol desaturase Erg3 increased the intracellular ROS levels and cell death, and this could be inhibited by the addition of calcium. The hexose transporter Hxt1 and the amino acid permease Agp1 play crucial roles in maintaining intracellular ROS levels, and calcium induced the expression of the HXT1 and AGP1 genes. The cytosolic calcium concentration was decreased in both the akr1Δ and erg3Δ mutants relative to wild-type cells, potentially lowering basal expression of HXT1 and AGP1. Moreover, the calcium/calcineurin signalling pathway also induced the expression of AKR1 and ERG3, indicating that Akr1 and Erg3 might perform functions that help yeast cells to survive under high calcium concentrations. Our results provided mechanistic insight into how calcium regulated intracellular ROS levels in yeast.

Identification of novel potential interaction partners of UDP-galactose (SLC35A2), UDP-N-acetylglucosamine (SLC35A3) and an orphan (SLC35A4) nucleotide sugar transporters

Nucleotide sugar transporters (NSTs) are ER and Golgi-resident members of the solute carrier 35 (SLC35) family which supply substrates for glycosylation by exchanging lumenal nucleotide monophosphates for cytosolic nucleotide sugars. Defective NSTs have been associated with congenital disorders of glycosylation (CDG), however, molecular basis of many types of CDG remains poorly characterized. To better understand the biology of NSTs, we identified potential interaction partners of UDP-galactose transporter (SLC35A2), UDP-N-acetylglucosamine transporter (SLC35A3) and an orphan nucleotide sugar transporter SLC35A4 of to date unassigned specificity. For this purpose, each of the SLC35A2-A4 proteins was used as a bait in four independent pull-down experiments and the identity of the immunoprecipitated material was discovered using MS techniques. From the candidate list obtained, we selected a few for which the interaction was confirmed in vitro using the NanoBiT system, a split luciferase-based luminescent technique. NSTs have been shown to interact with two ATPases (ATP2A2, ATP2C1), Golgi pH regulator B (GPR89B) and calcium channel (TMCO1), which may reflect the regulation of glycosylation by ion homeostasis, and with basigin (BSG). Our findings provide a starting point for the NST interaction network discovery in order to better understand how glycosylation is regulated and linked to other cellular processes. SIGNIFICANCE: Despite the facts that nucleotide sugar transporters are a key component of the protein glycosylation machinery, and deficiencies in their activity underlie serious metabolic diseases, biology, function and regulation of these essential proteins remain enigmatic. In this study we have advanced the field by identifying sets of new potential interaction partners for UDP-galactose transporter (SLC35A2), UDP-N-acetylglucosamine transporter (SLC35A3) and an orphan transporter SLC35A4 of yet undefined role. Several of these new interactions were additionally confirmed in vitro using the NanoBiT system, a split luciferase complementation assay. This work is also significant in that it addresses the overall challenge of discovering membrane protein interaction partners by a detailed comparison of 4 different co-immunoprecipitation strategies and by custom sample preparation and data processing workflows.

A Negative Feedback Loop in Ultraviolet A-Induced Senescence in Human Dermal Fibroblasts Formed by SPCA1 and MAPK

Secretory pathway calcium ATPase 1 (SPCA1) is a calcium pump localized specifically to the Golgi. Its effects on UVA-induced senescence have never been examined. In our study, expression of SPCA1 was increased in UVA-irradiated human dermal fibroblasts (HDFs) by activating mitogen-activated protein kinase (MAPK) and its downstream transcription factor, c-jun. Dual-luciferase reporter and chromatin immunoprecipitation assays revealed that c-jun regulated SPCA1 by binding to its promoter. Furthermore, downregulating SPCA1 with siRNA transfection aggravated UVA-induced senescence due to an elevation of intracellular calcium concentrations and a subsequent increase in reactive oxygen species (ROS) and MAPK activity. In contrast, overexpression of SPCA1 reduced calcium overload, consequently lowering the ROS level and suppressing MAPK activation. This alleviated the cellular senescence caused by UVA irradiation. These results indicated that SPCA1 might exert a protective effect on UVA-induced senescence in HDFs via forming a negative feedback loop. Specifically, activation of MAPK/c-jun triggered by UVA transcriptionally upregulated SPCA1. In turn, the increased SPCA1 lowered the intracellular Ca²⁺ level, probably through pumping Ca²⁺ into the Golgi, leading to a reduction of ROS, eventually decreasing MAPK activity and diminishing UVA-induced senescence.

Genome-wide association study identifies RNF123 locus as associated with chronic widespread musculoskeletal pain

Background and objectives

Chronic widespread musculoskeletal pain (CWP) is a symptom of fibromyalgia and a complex trait with poorly understood pathogenesis. CWP is heritable (48%–54%), but its genetic architecture is unknown and candidate gene studies have produced inconsistent results. We conducted a genome-wide association study to get insight into the genetic background of CWP.

Methods

Northern Europeans from UK Biobank comprising 6914 cases reporting pain all over the body lasting >3 months and 242 929 controls were studied. Replication of three independent genome-wide significant single nucleotide polymorphisms was attempted in six independent European cohorts (n=43 080; cases=14 177). Genetic correlations with risk factors, tissue specificity and colocalisation were examined.

Results

Three genome-wide significant loci were identified (rs1491985, rs10490825, rs165599) residing within the genes Ring Finger Protein 123 (RNF123), ATPase secretory pathway Ca²⁺transporting 1 (ATP2C1) and catechol-O-methyltransferase (COMT). The RNF123 locus was replicated (meta-analysis p=0.0002), the ATP2C1 locus showed suggestive association (p=0.0227) and the COMT locus was not replicated. Partial genetic correlation between CWP and depressive symptoms, body mass index, age of first birth and years of schooling were identified. Tissue specificity and colocalisation analysis highlight the relevance of skeletal muscle in CWP.

Conclusions

We report a novel association of RNF123 locus and a suggestive association of ATP2C1 locus with CWP. Both loci are consistent with a role of calcium regulation in CWP. The association with COMT, one of the most studied genes in chronic pain field, was not confirmed in the replication analysis.

Whole exome sequencing improves mutation detection in Hailey-Hailey disease

Hailey-Hailey disease (HHD) is an autosomal dominant monogenic disease that is defective in the ATP2C1 gene. In previous studies, Sanger sequencing was the main method applied to detect mutations in HHD patients, and no mutations in the ATP2C1 gene were found in 12-55% of those reported. The aim of our study was to carry out whole exome sequencing (WES) for the HHD patients in whom efforts to identify mutations by Sanger sequencing had failed, and to find a new pathogenic gene. WES was performed using genomic DNA from 13 HHD patients and 364 in-house healthy controls. Potential pathogenic mutations were subsequently validated by Sanger sequencing. As a result, eight mutations in the ATP2C1 gene were identified using WES. In the remaining five patients, we found one mutation in the ATP2A2 gene which was the causal gene of Darier's disease. Four patients had no detectable mutations in ATP2C1 and the other ATPase genes. Together with our previous study in 2019, the total mutation rate was calculated to be 47/52 (90.4%). These findings demonstrate that WES is capable of improving the mutation detection sensitivity in HHD compared with Sanger sequencing.

Crosstalk among Calcium ATPases: PMCA, SERCA and SPCA in Mental Diseases

Calcium in mammalian neurons is essential for developmental processes, neurotransmitter release, apoptosis, and signal transduction. Incorrectly processed Ca²⁺ signal is well-known to trigger a cascade of events leading to altered response to variety of stimuli and persistent accumulation of pathological changes at the molecular level. To counterbalance potentially detrimental consequences of Ca²⁺, neurons are equipped with sophisticated mechanisms that function to keep its concentration in a tightly regulated range. Calcium pumps belonging to the P-type family of ATPases: plasma membrane Ca²⁺-ATPase (PMCA), sarco/endoplasmic Ca²⁺-ATPase (SERCA) and secretory pathway Ca²⁺-ATPase (SPCA) are considered efficient line of defense against abnormal Ca²⁺ rises. However, their role is not limited only to Ca²⁺ transport, as they present tissue-specific functionality and unique sensitive to the regulation by the main calcium signal decoding protein—calmodulin (CaM). Based on the available literature, in this review we analyze the contribution of these three types of Ca²⁺-ATPases to neuropathology, with a special emphasis on mental diseases.

The role of the Golgi apparatus in disease (Review)

The Golgi apparatus is known to underpin many important cellular homeostatic functions, including trafficking, sorting and modifications of proteins or lipids. These functions are dysregulated in neurodegenerative diseases, cancer, infectious diseases and cardiovascular diseases, and the number of disease-related genes associated with Golgi apparatus is on the increase. Recently, many studies have suggested that the mutations in the genes encoding Golgi resident proteins can trigger the occurrence of diseases. By summarizing the pathogenesis of these genetic diseases, it was found that most of these diseases have defects in membrane trafficking. Such defects typically result in mislocalization of proteins, impaired glycosylation of proteins, and the accumulation of undegraded proteins. In the present review, we aim to understand the patterns of mutations in the genes encoding Golgi resident proteins and decipher the interplay between Golgi resident proteins and membrane trafficking pathway in cells. Furthermore, the detection of Golgi resident protein in human serum samples has the potential to be used as a diagnostic tool for diseases, and its central role in membrane trafficking pathways provides possible targets for disease therapy. Thus, we also introduced the clinical value of Golgi apparatus in the present review.

Generalized Hailey-Hailey disease: Novel splice-site mutations of ATP2C1 gene in Chinese population and a literature review

BACKGROUND

Hailey-Hailey disease (HHD; OMIM: 169600) is an autosomal dominate genodermatosis, characterized by recurrent blisters and erosions clinically and remarkable acantholysis pathologically. The underlying pathogenic factor is the mutation of ATP2C1 gene (OMIM: 604384), which encodes secretory pathway Ca²⁺ /Mn²⁺ -ATPase (SPCA1). Skin folds are the predilection site of HHD. Atypical cases with a generalized pattern have rarely been reported, making it prone to misdiagnosis.

METHODS

In this study, we presented three Chinese pedigrees of Hailey-Hailey disease with generalized skin lesions. ATP2C1 mutations were screened by DNA sequencing and their transcripts were further confirmed by minigene assay. We also performed a literature review of previously published generalized HHD over past two decades together with our cases.

RESULTS

Three splice-site mutations were identified: c.2487+1G>A, c.2126+1G>A, and c.1891-2A>G, which resulted in an exon 25-truncated transcript, two exon 22-truncated transcripts, and two exon 21-truncated transcripts, respectively. The c.2487+1G>A and the c.1891-2A>G mutations are novel mutations which have not been reported before. No clustered mutations of ATP2C1 gene were found in generalized HHD patients in literature along with our novel mutations.

CONCLUSION

We found no hot spot mutations in ATP2C1 correlated with the generalized pattern of HHD. Our study expanded the spectrum of ATP2C1 mutations, which would be useful for disease diagnosis and genetic counseling.

A Novel Microduplication Spanning Exons 8-16 of ATP2C1 That Was Undetectable by Standard Sanger Sequencing in a Japanese Patient With Hailey-Hailey Disease

Hailey-Hailey disease (HHD) is genetic skin disorder characterized by repeated and exacerbated skin lesions in friction regions. ATP2C1, encoding SPCA1, was demonstrated to be the responsible gene for HHD pathogenesis. However, for some cases, no ATP2C1 mutation could be determined by standard Sanger sequencing, thereby obscuring the cause and diagnosis of HHD. In this study, we investigated the possibility that HHD is caused by complex ATP2C1 defects using multiplex ligation-dependent probe amplification (MLPA) analysis for 10 of 50 cases in our institute without ATP2C1 mutations. In one female Japanese patient and her father, who also show HHD, MLPA followed by polymerase chain reaction (PCR) analyses revealed a novel duplication of exons 8-16 of ATP2C1. The duplication was predicted to add 20,615 base pairs, 882 nt, and 294-amino-acid residues to the genome, mRNA and SPCA1 protein, respectively. By reverse transcriptase-PCR using patient skin RNA, we could confirm that a larger transcript was produced and we found that the abundance of the normal transcript was clearly reduced in the patient. Putative structures of wild-type and duplicated proteins revealed differences in arrangement of SPCA1 domains that may have functional consequences. Strikingly, the phosphorylation and the nucleotide-binding domains were interrupted by insertion of a partial actuator, transmembrane, and phosphorylation domains. The additional 294 amino acids appear to disrupt SPCA1 structure and function, causing HHD. Our study expands the spectrum of genetic defects in HHD and showed that disruption of SPCA1 structure and function by the microduplication caused HHD in the patient and her father.

Biometals and glycosylation in humans: Congenital disorders of glycosylation shed lights into the crucial role of Golgi manganese homeostasis

About half of the eukaryotic proteins bind biometals that participate in their structure and functions in virtually all physiological processes, including glycosylation. After reviewing the biological roles and transport mechanisms of calcium, magnesium, manganese, zinc and cobalt acting as cofactors of the metalloproteins involved in sugar metabolism and/or glycosylation, the paper will outline the pathologies resulting from a dysregulation of these metals homeostasis and more particularly Congenital Disorders of Glycosylation (CDGs) caused by ion transporter defects. Highlighting of CDGs due to defects in SLC39A8 (ZIP8) and TMEM165, two proteins transporting manganese from the extracellular space to cytosol and from cytosol to the Golgi lumen, respectively, has emphasized the importance of manganese homeostasis for glycosylation. Based on our current knowledge of TMEM165 structure and functions, this review will draw a picture of known and putative mechanisms regulating manganese homeostasis in the secretory pathway.

SPCA1 governs the stability of TMEM165 in Hailey-Hailey disease

TMEM165 is a Golgi protein whose deficiency causes a Congenital Disorder of Glycosylation (CDG). We have demonstrated that Mn²⁺ supplementation could suppress the glycosylation defects observed in TMEM165-deficient cells and that TMEM165 was a Mn²⁺-sensitive protein. In the Golgi, the other transmembrane protein capable to regulate Mn²⁺/Ca²⁺ homeostasis is SPCA1, encoded by the ATP2C1 gene. A loss of one copy of the ATP2C1 gene leads to Hailey-Hailey Disease (HHD), an acantholytic skin disorder in Humans. Our latest results suggest an unexpected functional link between SPCA1 and TMEM165. In order to clarify this link in case of partial SPCA1 deficiency, HHD fibroblasts were used to assess TMEM165 expression, subcellular localization and Mn²⁺-induced degradation. No differences were observed regarding TMEM165 expression and localization in HHD patients' fibroblasts compared to control fibroblasts. Nevertheless, we demonstrated both for fibroblasts and keratinocytes that TMEM165 expression is more sensitive to MnCl₂ exposure in HHD cells than in control cells. We linked, using ICP-MS and GPP130 as a Golgi Mn²⁺ sensor, this higher Mn²⁺-induced sensitivity to a cytosolic Mn accumulation in MnCl₂ supplemented HHD fibroblasts. Altogether, these results link the function of SPCA1 to the stability of TMEM165 in a pathological context of Hailey-Hailey disease.

Novel and recurrent variants of ATP2C1 identified in patients with Hailey-Hailey disease

Hailey-Hailey disease (HHD) is a rare, late-onset autosomal dominant genodermatosis characterized by blisters, vesicular lesions, crusted erosions, and erythematous scaly plaques predominantly in intertriginous regions. HHD is caused by ATP2C1 mutations. About 180 distinct mutations have been identified so far; however, data of only few cases from Central Europe are available. The aim was to analyze the ATP2C1 gene in a cohort of Polish HHD patients. A group of 18 patients was enrolled in the study based on specific clinical symptoms. Mutations were detected using Sanger or next generation sequencing. In silico analysis was performed by prediction algorisms and dynamic structural modeling. In two cases, mRNA analysis was performed to confirm aberrant splicing. We detected 13 different mutations, including 8 novel, 2 recurrent (p.Gly850Ter and c.325-3 T > G), and 6 sporadic (c.423-1G > T, c.899 + 1G > A, p.Leu539Pro, p.Thr808TyrfsTer16, p.Gln855Arg and a complex allele: c.[1610C > G;1741 + 3A > G]). In silico analysis shows that all novel missense variants are pathogenic or likely pathogenic. We confirmed pathogenic status for two novel variants c.325-3 T > G and c.[1610C > G;1741 + 3A > G] by mRNA analysis. Our results broaden the knowledge about genetic heterogeneity in Central European patients with ATP2C1 mutations and also give further evidence that careful and multifactorial evaluation of variant pathogenicity status is essential.

Mechanisms of synergy of autoantibodies to M3 muscarinic acetylcholine receptor and secretory pathway Ca2+/Mn2+-ATPase isoform 1 in patients with non-desmoglein pemphigus vulgaris

Pemphigus vulgaris (PV) is a potentially lethal mucocutaneous blistering disease characterized by IgG autoantibodies (AuAbs) binding to epidermal keratinocytes and inducing a devastating blistering disease affecting oral and/or esophageal surfaces and, sometimes, also the skin. Anti-keratinocyte AuAbs developed by the desmoglein (Dsg) 1/3 AuAb-negative acute PV patients are pathogenic, as they induced acantholysis and epidermal split in the experimental models of PV in vitro and in vivo. These PV patients have various combinations of AuAbs to keratinocyte muscarinic acetylcholine receptor subtype M3 (M3AR), the secretory pathway Ca²⁺/Mn²⁺-ATPase isoform 1 (SPCA1), and desmocollin 3 whose relative concentrations correlate with the disease activity. In this study, we identified new molecular mechanisms of the synergistic cooperation of AuAbs to M3AR and SPCA1 in inducing acantholysis in the anti-Dsg 1/3 AuAb-negative PV patients. Anti-M3AR AuAb was found to play an important role in determining the level of intraepidermal split just above the basal cells, caspase to mediate early pro-apoptotic events triggered by anti-SPCA1 AuAb, and the neonatal Fc receptor (FcRn) to contribute to the pathobiological actions of both anti-M3AR and anti-SPCA1 AuAbs. Altogether, these novel results support our original hypothesis that pemphigus acantholysis is a complex disease process (also known as apoptolysis) initiated by AuAbs directed against different keratinocyte proteins that play important roles in supporting cell viability and regulating vital cell functions.

Mosaic variant in ATP2C1 presenting as relapsing linear acantholytic dermatosis

Relapsing linear acantholytic dermatosis (RLAD) is a rare disease that manifests as recurring episodes of crusted and vesicular lesions distributed in a Blaschkoid pattern with histology resembling Hailey-Hailey disease. RLAD, in the presence of generalized disease, has been shown to be a type 2 mosaic form of Hailey-Hailey disease. RLAD, without systemic disease, has been hypothesized to be type 1 mosaic Hailey-Hailey disease, but this assertion has lacked genetic conformation. To determine the genetic abnormalities causing RLAD, we performed exome sequencing of affected tissue and blood in one patient. Exome sequencing of a punch biopsy revealed a c.238A>T, p.(Lys80*) variant in ATP2C1 found in 26% of the reads from lesional skin but absent in germline DNA. This somatic variant causes a truncated protein that would likely result in loss of function. Our findings indicate that, in this patient, RLAD is a clinical presentation of type 1 segmental Hailey-Hailey disease. What's already known about this topic? Relapsing linear acantholytic dermatosis (RLAD) is postulated to be a mosaic form of Hailey-Hailey disease. This hypothesis has remained unproven for type 1 disease and the putative gene and driving genetic variants have remained unknown. What does this study add? Exome sequencing, performed on lesional skin and matched blood, found RLAD lesions to be mosaic for variants causing a premature stop codon in ATP2C1. Our findings support the hypothesis that RLAD is a type 1 segmental form of Hailey-Hailey disease caused by postzygotic variants in ATP2C1.

Characterization of Hailey-Hailey Disease-mutants in presence and absence of wild type SPCA1 using Saccharomyces cerevisiae as model organism

Hailey-Hailey disease is an autosomal genetic disease caused by mutations in one of the two ATP2C1 alleles encoding the secretory pathway Ca²⁺/Mn²⁺-ATPase, hSPCA1. The disease almost exclusively affects epidermis, where it mainly results in acantholysis of the suprabasal layers. The etiology of the disease is complex and not well understood. We applied a yeast based complementation system to characterize fourteen disease-causing ATP2C1 missense mutations in presence or absence of wild type ATP2C1 or ATP2A2, encoding SERCA2. In our yeast model system, mutations in ATP2C1 affected Mn²⁺ transport more than Ca²⁺ transport as twelve out of fourteen mutations were unable to complement Mn²⁺ sensitivity while thirteen out of fourteen to some extent complemented the high Ca²⁺requirement. Nine out of fourteen mutations conferred a cold sensitive complementation capacity. In absence of a wild type ATP2C1 allele, twelve out of fourteen mutations induced an unfolded protein response indicating that in vivo folding of hSPCA1 is sensitive to disease causing amino acid substitutions and four of the fourteen mutations caused the hSPCA1 protein to accumulate in the vacuolar membrane. Co-expression of either wild type ATP2C1 or ATP2A2 prevented induction of the unfolded protein response and hSPCA1 mis-localization.

Treatment of Hailey-Hailey disease with narrowband phototherapy and acitretin: A case report

The Hailey–Hailey disease, or familial benign chronic pemphigus, is an autosomal dominant genodermatosis affecting mainly intertriginous areas. It manifests itself in painful blisters, erosions, and cracks and has a chronic course with frequent flares, significantly impacting patients’ quality of life. Presently, there is no cure, but multiple treatment modalities are available. Most evidence supports treatment with topical steroids and antimicrobials. Treatment of recalcitrant disease has been shown to benefit from the addition of oral antibiotics, Naltrexone, systemic retinoids, botulinum toxin A injections, laser treatment, and surgical excision. We describe a case of refractory Hailey–Hailey disease for which most of the abovementioned options failed, but which demonstrated significant improvement following a combination of oral acitretin and narrowband ultraviolet-B phototherapy. To achieve remission, the patient received 30 sessions three times per week with the increment of 20 mJ/cm² per session and oral acitretin 25 mg PO daily.

Synergy among non-desmoglein antibodies contributes to the immunopathology of desmoglein antibody-negative pemphigus vulgaris

Pemphigus vulgaris (PV) is a potentially lethal mucocutaneous blistering disease characterized by IgG autoantibodies (AuAbs) binding to epidermal keratinocytes and inducing this devastating disease. Here, we observed that non-desmoglein (Dsg) AuAbs in the sera of patients with Dsg1/3 AuAb-negative acute PV are pathogenic, because IgGs from these individuals induced skin blistering in neonatal mice caused by suprabasal acantholysis. Serum levels of AuAbs to desmocollin 3 (Dsc3), M3 muscarinic acetylcholine receptor (M3AR), and secretory pathway Ca2+/Mn2+-ATPase isoform 1 (SPCA1) correlated with the disease stage of PV. Moreover, AuAb absorption on recombinant Dsc3, M3AR, or SPCA1 both prevented skin blistering in the passive transfer of AuAbs model of PV in BALB/c mice and significantly decreased the extent of acantholysis in a neonatal mouse skin explant model. Although acantholytic activities of each of these immunoaffinity-purified AuAbs could not induce a PV-like phenotype, their mixture produced a synergistic effect manifested by a positive Nikolskiy sign in the skin of neonatal mice. The downstream signaling of all pathogenic non-Dsg AuAbs involved p38 mitogen-activated protein kinase (MAPK)-mediated phosphorylation and elevation of cytochrome c release and caspase 9 activity. Anti-Dsc3 and anti-SPCA1 AuAbs also activated SRC proto-oncogene, nonreceptor tyrosine kinase (SRC). Of note, although a constellation of non-Dsg AuAbs apparently disrupted epidermal integrity, elimination of a single pathogenic AuAb could prevent keratinocyte detachment and blistering. Therefore, anti-Dsg1/3 AuAb-free PV can be a model for elucidating the roles of non-Dsg antigen-specific AuAbs in the physiological regulation of keratinocyte cell-cell adhesion and blister development.

Hailey-Hailey disease: the role of azathioprine an immunomodulator

Hailey-Hailey disease (HHD) is a rare autosomal dominant hereditary blistering and erosions disorder affecting the intertriginous regions of the body. There is still no treatment protocol for this disease thus clinicians are highly advised to draw up individualized treatment plan. In this case report, we discuss a case of HHD in a 58-year-old Chinese man who was successfully treated with azathioprine in Hubei province.

Hailey-Hailey-Like Pattern of Acantholysis on the Scalp Should Raise the Possibility of Incipient Pemphigus Vulgaris

Hailey-Hailey disease (familial benign chronic pemphigus) is a genodermatosis with a typical clinical presentation of macerated plaques involving intertriginous areas of the body and affects multiple family members. Epidermal acanthosis, incipient, and completed acantholysis of many of the spinous keratinocytes of the epidermis and foci of dyskeratosis are well-recognized histologic findings. We have observed solitary lesions on the "scalp" of patients having a Hailey-Hailey-like pattern, and not the suprabasilar clefting of pemphigus represents the first manifestation of pemphigus vulgaris, which was confirmed with direct immunofluorescence in all our patients.

Altered levels of focal adhesion and extracellular matrix-receptor interacting proteins were identified in Hailey-Hailey disease by quantitative iTRAQ proteome analysis

Benign chronic familial pemphigus or Hailey-Hailey disease (HHD, OMIM 169600) is a rare, autosomal dominant blistering skin disorder characterized by suprabasal cell separation (acantholysis) of the epidermis. To date, the proteomic changes in skin lesions from HHD patients has not been reported yet. In this study, a sample of skin lesions from HHD patients was collected for isobaric tags for relative and absolute quantitation to analyze proteome changes compared with unaffected individuals. The 134 differentially expressed proteins were assigned to at least one Gene Ontology term, and 123 annotated proteins with significant matches were assigned to 187 known metabolic or signaling pathways listed in the Kyoto Encyclopedia of Genes and Genomes. Most of the altered proteins in skin lesions of HHD patients were enriched in pathways involved in the PI3K-Akt signaling, focal adhesion, extracellular matrix (ECM)-receptor interaction, and protein digestion and absorption, such as collagen family members, microfibril-associated glycoprotein 4 and plakophilin. The changes of proteins related to cell adhesion, ECM-receptor interaction, and protein folding and glycosylation suggested that strategy targeted to alter cell junction and extracellular microenvironment might provide a potential treatment for HHD.

A novel splice-site mutation in the ATP2C1 gene of a Chinese family with Hailey-Hailey disease

Hailey-Hailey disease (HHD), also known as familial benign chronic pemphigus, is an autosomal dominant genodermatosis. It is characterized by erosions, blisters and erythematous plaques at sites of friction or intertriginous areas. The pathogenic gene of HHD has been revealed as the ATPase secretory pathway Ca²⁺ transporting 1 gene ( ATP2C1), which encodes the protein, secretory pathway Ca ²⁺/Mn ²⁺-ATPase 1 (SPCA1). ATP2C1 gene mutations are responsible for HHD by resulting in abnormal Ca ²⁺ homeostasis in the skin and giving rise to acantholysis, a characteristic pathology of HHD. In this study, a four-generation family containing three HHD sufferers was recruited. Direct sequencing of the ATP2C1 gene was performed in the proband and other available family members. Reverse-transcriptase polymerase chain reaction analysis was conducted to show the potential variant effect on ATP2C1 splicing. A novel heterozygous c.325-2A>G transition at the splice acceptor site of intron 4 in the ATP2C1 gene was identified, and it co-segregated with the disease in this family. The mutation resulted in exon 5 skipping and an in-frame deletion of 12 amino acids (p.Ala109_Gln120del) in SPCA1. This splice-site mutation may be responsible for HHD in this family. This study would further expand the mutation spectrum of the ATP2C1 gene and may be helpful in the genetic counseling and prenatal diagnosis of HHD.

Diverse Viruses Require the Calcium Transporter SPCA1 for Maturation and Spread

Respiratory and arthropod-borne viral infections are a global threat due to the lack of effective antivirals and vaccines. A potential strategy is to target host proteins required for viruses but non-essential for the host. To identify such proteins, we performed a genome-wide knockout screen in human haploid cells and identified the calcium pump SPCA1. SPCA1 is required by viruses from the Paramyxoviridae, Flaviviridae, and Togaviridae families, including measles, dengue, West Nile, Zika, and chikungunya viruses. Calcium transport activity is required for SPCA1 to promote virus spread. SPCA1 regulates proteases within the trans-Golgi network that require calcium for their activity and are critical for virus glycoprotein maturation. Consistent with these findings, viral glycoproteins fail to mature in SPCA1-deficient cells preventing viral spread, which is evident even in cells with partial loss of SPCA1. Thus, SPCA1 is an attractive antiviral host target for a broad spectrum of established and emerging viral infections.

Yeast-Based Screen to Identify Natural Compounds with a Potential Therapeutic Effect in Hailey-Hailey Disease

The term orthodisease defines human disorders in which the pathogenic gene has orthologs in model organism genomes. Yeasts have been instrumental for gaining insights into the molecular basis of many human disorders, particularly those resulting from impaired cellular metabolism. We and others have used yeasts as a model system to study the molecular basis of Hailey-Hailey disease (HHD), a human blistering skin disorder caused by haploinsufficiency of the gene ATP2C1 the orthologous of the yeast gene PMR1. We observed that K. lactis cells defective for PMR1 gene share several biological similarities with HHD derived keratinocytes. Based on the conservation of ATP2C1/PMR1 function from yeast to human, here we used a yeast-based assay to screen for molecules able to influence the pleiotropy associated with PMR1 deletion. We identified six compounds, Kaempferol, Indirubin, Lappaconite, Cyclocytidine, Azomycin and Nalidixic Acid that induced different major shape phenotypes in K. lactis. These include mitochondrial and the cell-wall morphology-related phenotypes. Interestingly, a secondary assay in mammalian cells confirmed activity for Kaempferol. Indeed, this compound was also active on human keratinocytes depleted of ATP2C1 function by siRNA-treatment used as an in-vitro model of HHD. We found that Kaempferol was a potent NRF2 regulator, strongly inducing its expression and its downstream target NQO1. In addition, Kaempferol could decrease oxidative stress of ATP2C1 defective keratinocytes, characterized by reduced NRF2-expression. Our results indicated that the activation of these pathways might provide protection to the HHD-skin cells. As oxidative stress plays pivotal roles in promoting the skin lesions of Hailey-Hailey, the NRF2 pathway could be a viable therapeutic target for HHD.