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Psoriasis is a chronic, immune-mediated inflammatory disease which pathogenesis is closely linked to γδ T cells. Recently, a critical role for butyrophilin 3A1 (BTN3A1) in mediating the activation of Vγ9Vδ2 T cells, which are reported to redistribute from blood to the perturbed skin lesions in psoriasis, has been proposed. Additional molecular partners, including RhoB and periplakin, have also been speculated to interact with BTN3A1 in modulating Vγ9Vδ2 T-cell activation. Immunohistochemical staining was performed to examine the expressions of BTN3A1, RhoB, and the plakin family members, including periplakin, epiplakin, and envoplakin in the psoriasis vulgaris lesions as compared with the normal control. The expressions of BTN3A1 and RhoB were found significantly upregulated in the psoriatic lesions. Besides, a downregulation of periplakin and an upregulation of epiplakin were noticed in the psoriasis vulgaris lesions. Our data suggest that BTN3A1 and RhoB might participate in the pathogenesis of psoriasis through Vγ9Vδ2 T-cell responses. In addition, a potential involvement of the plakin protein family, especially periplakin and epiplakin, in psoriasis pathology was proposed.

Tetraspanins are master organizers of the cell membrane. Recent evidence suggests that tetraspanins themselves may become crowded by virus particles and that these crowds/aggregates co-internalize with the viral particles. Using microscopy, we studied human papillomavirus (HPV) type 16-dependent aggregates on the cell surface of tetraspanin overexpressing keratinocytes. We find that aggregates are (1) rich in at least two different tetraspanins, (2) three-dimensional architectures extending up to several micrometers into the cell, and (3) decorated intracellularly by filamentous actin. Moreover, in cells not overexpressing tetraspanins, we note that obscurin-like protein 1 (OBSL1), which is thought to be a cytoskeletal adaptor, associates with filamentous actin. We speculate that HPV contact with the cell membrane could trigger the formation of a large tetraspanin web. This web may couple the virus contact site to the intracellular endocytic actin machinery, possibly involving the cytoskeletal adaptor protein OBSL1. Functionally, such a tetraspanin web could serve as a virus entry platform, which is co-internalized with the virus particle. Electronic supplementary material The online version of this article (10.1007/s00430-020-00683-1) contains supplementary material, which is available to authorized users.

Eosinophilic esophagitis (EoE) is a chronic allergic inflammatory disease with a complex underlying genetic etiology. Herein, we conduct whole-exome sequencing of a multigeneration EoE pedigree (discovery set) and 61 additional multiplex families with EoE (replication set). A series of rare, heterozygous, missense variants are identified in the genes encoding the desmosome-associated proteins DSP and PPL in 21% of the multiplex families. Esophageal biopsies from patients with these variants retain dilated intercellular spaces and decrease DSP and PPL expression even during disease remission. These variants affect barrier integrity, cell motility and RhoGTPase activity in esophageal epithelial cells and have increased susceptibility to calpain-14–mediated degradation. An acquired loss of esophageal DSP and PPL is present in non-familial EoE. Taken together, herein, we uncover a pathogenic role for desmosomal dysfunction in EoE, providing a deeper mechanistic understanding of tissue-specific allergic responses., Eosinophilic esophagitis (EoE) is a chronic allergic inflammatory disease with a complex underlying genetic etiology. Here, the authors identify a series of rare variants in DSP and PPL in multiplex families with EoE and uncover a pathogenic role for desmosomal dysfunction in EoE.

Paraneoplastic pemphigus (PNP) is one of the least investigated and rare forms of bullous dermatoses, which comes from underlying neoplasm. The article presents a literature review of dermatologist`s longstanding international experience about etiology, pathogenesis, diagnostics and treatment of this disease. According to the research results of native and foreign authors systematization of modern diagnostic methods of PNP and detectable antigens was performed.Conflict of interest: the authors state that there is no potential conflict of interest requiring disclosure in this article.

This study aimed to identify stromal molecular signatures associated with breast and prostate cancer. The microarray data GSE26910 was downloaded from Gene Expression Omnibus database, including six invasive breast tumor stroma, six matched normal controls, six invasive prostate tumor stroma, and six matched controls. The differentially expressed genes (DEGs) in invasive breast and prostate tumors stroma were, respectively, identified. Then common stromal genes (B_P.DEGs) were further screened. Protein-protein interaction (PPI) network was constructed and Gene Ontology analysis was performed. Besides, gene-chemical interactions were mapped in Comparative Toxicogenomics Database to screen the chemicals related to feature genes. The results showed that, in total, 16 B_P.DEGs were identified. Thereinto, only seven B_P.DEGs were mapped into PPI, and only four functional modules (adenylate cyclase activating polypeptide 1 (pituitary) receptor type I (ADCYAP1R1) module, aspartoacylase (ASPA) module, glutathione S-transferase mu 5 (GSTM5) module, and periplakin (PPL) module) were involved in important biological processes associated with cancer progression. In addition, the chemicals, such as dihydrotestosterone, apocarotenal, testosterone, and progesterone, were screened for the roles of feature genes in the progression of breast and prostate cancer. In conclusion, ADCYAP1R1, GSTM5, and PPL were stromal molecular signatures and might play a key role in the progression of breast and prostate cancer.

Planar cell polarity (PCP) regulates coordinated cellular polarity among neighboring cells to establish a polarity axis parallel to the plane of the tissue. Disruption in PCP results in a range of developmental anomalies and diseases. A key feature of PCP is the polarized and asymmetric localization of several membrane PCP proteins, which is essential to establish the polarity axis to orient cells coordinately. However, the machinery that regulates the asymmetric partition of PCP proteins remains largely unknown. In the present study, we show Van gogh-like 2 (Vangl2) in early and recycling endosomes as made evident by colocalization with diverse endosomal Rab proteins. Vangl2 biochemically interacts with adaptor protein-3 complex (AP-3). Using short hairpin RNA knockdown, we found that Vangl2 subcellular localization was modified in AP-3–depleted cells. Moreover, Vangl2 membrane localization within the cochlea is greatly reduced in AP-3–deficient mocha mice, which exhibit profound hearing loss. In inner ears from AP-3–deficient mocha mice, we observed PCP-dependent phenotypes, such as misorientation and deformation of hair cell stereociliary bundles and disorganization of hair cells characteristic of defects in convergent extension that is driven by PCP. These findings demonstrate a novel role of AP-3–mediated sorting mechanisms in regulating PCP proteins.

The plakin family of cytoskeletal proteins play an important role in cancer progression yet are under-studied in cancer, especially ovarian cancer. These large cytoskeletal proteins have primary roles in the maintenance of cytoskeletal integrity but are also associated with scaffolds of intermediate filaments and hemidesmosomal adhesion complexes mediating signalling pathways that regulate cellular growth, migration, invasion and differentiation as well as stress response. Abnormalities of plakins, and the closely related spectraplakins, result in diseases of the skin, striated muscle and nervous tissue. Their prevalence in epithelial cells suggests that plakins may play a role in epithelial ovarian cancer progression and recurrence. In this review article, we explore the roles of plakins, particularly plectin, periplakin and envoplakin in disease-states and cancers with emphasis on ovarian cancer. We discuss the potential role the plakin family of proteins play in regulating cancer cell growth, survival, migration, invasion and drug resistance. We highlight potential relationships between plakins, epithelial-mesenchymal transition (EMT) and cancer stem cells (CSCs) and discuss how interaction of these processes may affect ovarian cancer progression, chemoresistance and ultimately recurrence. We propose that molecular changes in the expression of plakins leads to the transition of benign ovarian tumours to carcinomas, as well as floating cellular aggregates (commonly known as spheroids) in the ascites microenvironment, which may contribute to the sustenance and progression of the disease. In this review, attempts have been made to understand the crucial changes in plakin expression in relation to progression and recurrence of ovarian cancer. Video Abstract Supplementary Information The online version contains supplementary material available at 10.1186/s12964-021-00726-x.

Use of immunosuppressive drugs is still unavoidable in kidney-transplanted patients. Since their discovery, calcineurin inhibitors (CNI) have been considered the first-line immunosuppressive agents, in spite of their known nephrotoxicity. Chronic CNI toxicity (CNIT) may lead to kidney fibrosis, a threatening scenario for graft survival. However, there is still controversy regarding CNIT diagnosis, monitoring and therapeutic management, and their specific effects at the molecular level are not fully known. Aiming to better characterize CNIT patients, in the present study, we collected urine from kidney-transplanted patients treated with CNI who (i) had a normal kidney function, (ii) suffered CNIT, or (iii) presented interstitial fibrosis and tubular atrophy (IFTA). Urinary extracellular vesicles (uEV) were enriched and the proteome was analyzed to get insight into changes happening during CNI. Members of the uroplakin and plakin families were significantly upregulated in the CNIT group, suggesting an important role in CNIT processes. Although biomarkers cannot be asserted from this single pilot study, our results evidence the potential of uEV as a source of non-invasive protein biomarkers for a better detection and monitoring of this renal alteration in kidney-transplanted patients.

Autoimmune blistering diseases (AIBDs) are a group of fatal diseases with specific autoantibodies. BIOCHIP mosaic is a novel and all-in-one measure used for the rapid diagnosis of AIBDs. To evaluate the diagnostic accuracy based on BIOCHIP mosaic (FA1501-1005-60) in Chinese patients with AIBDs. Seventy-seven patients with AIBDs and 20 controls were enrolled. The BIOCHIP mosaic was performed using both serum and plasma samples. Based on BIOCHIP mosaic, the data from paired plasma and serum samples demonstrated a high degree of concordance (Cohen’s kappa = 0.896–1.000) for autoantibodies against Dsgl, Dsg3, BP180-NC16A-4X, BP230gC, prickle-cell desmosomes, and pemphigoid antigens. Moreover, BIOCHIP mosaic also demonstrated a high degree of consistency for the detection rate of anti-Dsgl, Dsg3, plakins, BP180-NC16A-4X and non-collagenous domain of type VII collagen autoantibodies for the diagnosis of pemphigus foliaceus (77.3%), pemphigus vulgaris (88.6%), paraneoplastic pemphigus (100.0%), bullous pemphigoid (92.8%) and epidermolysis bullosa acquisita (99.0%), respectively. Using BIOCHIP mosaic, serum and plasma samples may be used interchangeably at 1/10 dilution. Overall, the BIOCHIP mosaic was shown to be a useful and accurate tool for the diagnosis of AIBDs.

Cell fate decisions are essential for tissue development and homeostasis and can be induced by chemical and mechanical inputs. While the mechanisms by which chemical signals control cell fate have been well studied, how mechanical inputs impact cell fate decisions are not well understood. Here, we use the well-defined system of keratinocyte differentiation in the skin to define mechanisms by which mechanical inputs control cell fate. Although mechanical signals are known to induce epidermal differentiation, whether and how direct force transmission to the nucleus regulates cell fate decisions remains unknown. Here, we measure tension on the nucleus through the Linker of Nucleoskeleton and Cytoskeleton (LINC) complexes using a molecular biosensor during keratinocyte differentiation. We show that undifferentiated epidermal stem cells display high tension on the LINC complex when integrins are engaged. During differentiation, tension decreases on the LINC complex and on A-type lamins, suggesting that the state of the nuclear lamina is altered during differentiation. LINC complex ablation in mice reveals that LINC complexes are required to repress epidermal differentiation in vitro and in vivo , suggesting that force transduction from engaged integrins to the nucleus plays a role in maintaining keratinocyte progenitors. This work reveals a direct mechanotransduction pathway capable of relaying adhesion-specific signals to regulate cell fate.

Actin filaments and microtubules create diverse cellular protrusions, but intermediate filaments, the strongest and most stable cytoskeletal elements, are not known to directly participate in the formation of protrusions. Here we show that keratin intermediate filaments directly regulate the morphogenesis of microridges, elongated protrusions arranged in elaborate maze-like patterns on the surface of mucosal epithelial cells. We found that microridges on zebrafish skin cells contained both actin and keratin filaments. Keratin filaments stabilized microridges, and overexpressing keratins lengthened them. Envoplakin and periplakin, plakin family cytolinkers that bind F-actin and keratins, localized to microridges, and were required for their morphogenesis. Strikingly, plakin protein levels directly dictate microridge length. An actin-binding domain of periplakin was required to initiate microridge morphogenesis, whereas periplakin-keratin binding was required to elongate microridges. These findings separate microridge morphogenesis into distinct steps, expand our understanding of intermediate filament functions, and identify microridges as protrusions that integrate actin and intermediate filaments., eLife digest Cells adopt a wide array of irregular and bumpy shapes, which are scaffolded by an internal structure called the cytoskeleton. This network of filaments can deform the cell membrane the way tent poles frame a canvas. Cells contain three types of cytoskeleton elements (actin filaments, intermediate filaments, and microtubules), each with unique chemical and mechanical properties. One of the main roles of the cytoskeleton is to create protrusions, a range of structures that ‘stick out’ of a cell to allow movement and interactions with the environment. Both actin filaments and microtubules help form protrusions, but the role of intermediate filaments remains unclear. Microridges are a type of protrusion found on cells covered by mucus, for instance on the surface of the eye, inside the mouth, or on fish skin. These small bumps are organised on the membrane of a cell in fingerprint-like arrangements. Scientists know that actin networks are necessary for microridges to form; yet, many structures supported by actin filaments are not stable over time, suggesting that another component of the cytoskeleton might be lending support. Intermediate filaments are the strongest, most stable type of cytoskeleton element, and they can connect to actin filaments via linker proteins. However, research has yet to show that this kind of cooperation happens in any membrane protrusion. Here, Inaba et al. used high-resolution microscopy to monitor microridge development in the skin of live fish. In particular, they focused on a type of intermediate filaments known as keratin filaments. This revealed that, inside microridges, the keratin and actin networks form alongside each other, with linker proteins called Envoplakin and Periplakin connecting the two structures together. Genetic experiments revealed that Envoplakin and Periplakin must attach to actin for microridges to start forming. However, the two proteins bind to keratin for protrusions to grow. This work therefore highlights how intermediate filaments and linker proteins contribute to the formation of these structures. Many tissues must be covered in mucus to remain moist and healthy. As microridges likely contribute to mucus retention, the findings by Inaba et al. may help to better understand how disorders linked to problems in mucus emerge.

Plakin proteins form connections that link the cell membrane to the intermediate filament cytoskeleton. Their interactions are mediated by a highly conserved linker domain through an unresolved mechanism. Here analysis of the human periplakin linker domain structure reveals a bi-lobed module transected by an electropositive groove. Key basic residues within the periplakin groove are vital for co-localization with vimentin in human cells and compromise direct binding which also requires acidic residues D176 and E187 in vimentin. We propose a model whereby basic periplakin linker domain residues recognize acidic vimentin side chains and form a complementary binding groove. The model is shared amongst diverse linker domains and can be used to investigate the effects of pathogenic mutations in the desmoplakin linker associated with arrhythmogenic right ventricular cardiomyopathy. Linker modules either act solely or collaborate with adjacent plakin repeat domains to create strong and adaptable tethering within epithelia and cardiac muscle., Odinstova, Mohammed, Trieber et al. use structure-based mutagenesis to identify key residues in human periplakin and desmoplakin linker modules required for co-localization with vimentin intermediate filaments. They show that vimentin D176 and E187 are required for direct binding with the periplakin linker.

Structure 27(6), 952 - 964.e6 (2019). doi:10.1016/j.str.2019.03.016, Mechanical stability of epithelia requires firm attachment to the basement membrane via hemidesmosomes. Dysfunction of hemidesmosomal proteins causes severe skin-blistering diseases. Two plakins, plectin and BP230 (BPAG1e), link the integrin α6β4 to intermediate filaments in epidermal hemidesmosomes. Here, we show that a linear sequence within the isoform-specific N-terminal region of BP230 binds to the third and fourth FnIII domains of β4. The crystal structure of the complex and mutagenesis analysis revealed that BP230 binds between the two domains of β4. BP230 induces closing of the two FnIII domains that are locked in place by an interdomain ionic clasp required for binding. Disruption of BP230-β4 binding prevents recruitment of BP230 to hemidesmosomes in human keratinocytes, revealing a key role of this interaction for hemidesmosome assembly. Phosphomimetic substitutions in β4 and BP230 destabilize the complex. Thus, our study provides insights into the architecture of hemidesmosomes and potential mechanisms of regulation., Published by Cell Press, Cambridge, Mass.

We explored the potential of combining carcinoembryonic antigen (CEA) and salivary mRNAs for gastric cancer (GC) detection.This study included 2 phases of study: a biomarker discovery phase and an independent validation phase. In the discovery phase, we measured CEA levels in blood samples and expression level of messenger RNAs (SPINK7, PPL, SEMA4B, SMAD4) in saliva samples of 140 GC patients and 140 healthy controls. We evaluated the clinical performance of each biomarker and developed a predictive model using machine-learning algorithm to differentiate GC patients and healthy controls.Our biomarker panel successfully discriminated GC patients from healthy controls with both high sensitivity (0.94) and high specificity (0.91). We next applied our biomarker panel in the independent validation phase, in which we recruited a new patient cohort of 60 GC patients and 60 healthy controls. Using our biomarker panel, the GC patients were discriminated from healthy controls in the validation phase, with sensitivity of 0.92 and specificity of 0.87.A combination of blood CEA and salivary messenger RNA could be a promising approach to detect GC.

The use of EGFR inhibitors on oral squamous cell carcinoma (OSCC) as monotherapy yielded modest clinical outcomes and therefore would benefit from biomarkers that could predict which patient subsets are likely to respond. Here, we determined the efficacy of erlotinib in OSCC cell lines, and by comparing sensitive and resistant lines to identify potential biomarkers. We focused on the 4717C > G polymorphism in periplakin (PPL) where the CC genotype was associated with erlotinib resistance. To validate this, erlotinib-resistant cell lines harbouring CC genotype were engineered to overexpress the GG genotype and vice versa. Isogenic cell lines were then studied for their response to erlotinib treatment. We demonstrated that overexpression of the GG genotype in erlotinib-resistant lines sensitized them to erlotinib and inhibition of AKT phosphorylation. Similarly, the expression of the CC genotype conferred resistance to erlotinib with a concomitant increase in AKT phosphorylation. We also demonstrated that cell lines with the CC genotype generally are more resistant to other EGFR inhibitors than those with the GG genotype. Overall, we showed that a specific polymorphism in the PPL gene could confer resistance to erlotinib and other EGFR inhibitors and further work to evaluate these as biomarkers of response is warranted.

Cancer is a highly lethal disease that is characterized by aberrant cell proliferation, migration, and adhesion, which are closely related to the dynamic changes of cytoskeletons and cytoskeletal-adhesion. These will further result in cell invasion and metastasis. Plakins are a family of giant cytolinkers that connect cytoskeletal elements with each other and to junctional complexes. With various isoforms composed of different domain structures, mammalian plakins are broadly expressed in numerous tissues. They play critical roles in many cellular processes, including cell proliferation, migration, adhesion, and signaling transduction. As these cellular processes are key steps in cancer development, mammalian plakins have in recent years attracted more and more attention for their potential roles in cancer. Current evidence shows the importance of mammalian plakins in various human cancers and demonstrates mammalian plakins as potential biomarkers for cancer. Here, we introduce the basic characteristics of mammalian plakins, review the recent advances in understanding their biological functions, and highlight their roles in human cancers, based on studies performed by us and others. This will provide researchers with a comprehensive understanding of mammalian plakins, new insights into the development of cancer, and novel targets for cancer diagnosis and therapy.

IF 12.784 (2016); International audience; Periplakin is a component of the desmosomes that acts as a cytolinker between intermediate filament scaffolding and the desmosomal plaque. Periplakin is strongly expressed by epithelial cells in the lung and is a target antigen for autoimmunity in idiopathic pulmonary fibrosis. The aim of this study was to determine the role of periplakin during lung injury and remodeling in a mouse model of lung fibrosis induced by bleomycin. We found that periplakin expression was downregulated in the whole lung and in alveolar epithelial cells following bleomycin-induced injury. Deletion of the Ppl gene in mice improved survival and reduced lung fibrosis development after bleomycin-induced injury. Notably, Ppl deletion promoted an antiinflammatory alveolar environment linked to profound changes in type 2 alveolar epithelial cells, including overexpression of antiinflammatory cytokines, decreased expression of profibrotic mediators, and altered cell signaling with a reduced response to TGF-β1. These results identify periplakin as a previously unidentified regulator of the response to injury in the lung.

Periplakin (PPL), a member of the plakin family of proteins that localizes to desmosomes and intermediate filaments, is downregulated in human esophageal squamous cell carcinoma (ESCC). Little is known, however, about the molecular mechanism underlying the regulation of PPL expression and the contribution of PPL loss to the malignant property of the cancer is unclear. We demonstrated that PPL mRNA expression was significantly reduced in ESCC tissues compared with that in normal tissues. Therefore, we hypothesized that CpG hypermethylation is the cause of the downregulation of PPL. Bisulfite-pyrosequencing of 17 cases demonstrated that the frequency of PPL methylation was higher in ESCC tissues than in normal tissues. When human ESCC cell lines were treated with 5-aza-2′-deoxycytidine (5-aza-dC), a DNA-methyltransferase inhibitor, PPL transcription was induced. Human KYSE270 ESCC cells do not stratify under ordinary culture conditions and rarely produce desmosomes; however, the forced expression of PPL promoted cell stratification. PPL induction also promoted adhesion to extracellular matrix but delayed cell migration. The abundance of desmosome-like structures was greatly increased in PPL transfectant as determined by transmission electron microscopy. Very low expression of another desmosome protein EVPL in ESCC, even in PPL transfectant, also supported the significant role of PPL in desmosome formation and cell stratification. Our results first indicate that the downregulation of PPL mediated by DNA hypermethylation, which may play an important role in the loss of ESCC stratification and likely in metastatic phenotype.

Congenital epidermolysis bullosa (CEB) is an extensive group of hereditary skin diseases, the differential diagnosis of which is a challenge due to the rarity of this pathology and the diversity of its clinical manifestations. The determination of the type of CEB makes it possible to estimate its prognosis and to facilitate a prenatal diagnosis.to optimize the morphological diagnosis of different types of CEB.28 skin biopsies from 14 patients with different types of CEB were investigated. The investigators performed routine histological examination of skin fragments taken from a bullous area and immunofluorescence antigen mapping using the indirect immunofluorescence test (IIFT) with antibodies against structural proteins of the dermal-epidermal junction (laminin α3, β3, and γ2 chains, keratins 5 and 14, types VII and XVII collagen, α6 and β4 integrin subunits, desmoplakin, plectin, kindlin-1, and plakophillin) of the apparently unaffected skin. The intact skin of healthy individuals, which had been obtained during cosmetic operations, was used as controls in IIFT.Immunofluorescence antigen mapping could determine the type of CEB in all cases and in 86% of cases identify the protein, the impaired production of which was responsible for the development of the disease.Immunofluorescence antigen mapping is an integral part of the comprehensive morphological diagnosis of CEB, acting as an intermediate between the morphological verification of CEB diagnosis and the targeted search for mutations by a molecular genetic method.Врожденный буллезный эпидермолиз (ВБЭ) представляет собой обширную группу наследственных заболеваний кожи, дифференциальная диагностика которых сложна в связи с редкостью данной патологии и многообразием ее клинических проявлений. Определение типа ВБЭ позволяет оценить прогноз заболевания и облегчить проведение пренатальной диагностики. Цель - оптимизация морфологической диагностики различных видов ВБЭ. Материал и методы. Исследовано 28 биоптатов кожи от 14 пациентов с различными видами ВБЭ. Проводилось рутинное гистологическое исследование фрагментов кожи, взятых в области пузыря, и иммунофлюоресцентное антигенное картирование с применением непрямой реакции иммунофлюоресценции (нРИФ) с антителами к структурным белкам дермо-эпидермального соединения (α3-, β3- и γ2-цепям ламинина, кератинам 5 и 14, коллагенам VII и XVII типов, α6- и β4-субъединицам интегрина, десмоплакину, плектину, киндлину-1, плакофилину) видимо непораженной кожи. В качестве контроля при проведении нРИФ использовалась неизмененная кожа здоровых лиц, полученная при косметических операциях. Результаты. Метод иммунофлюоресцентного антигенного картирования позволил во всех случаях установить тип ВБЭ и в 86% - белок, нарушение продукции которого обусловило развитие заболевания. Заключение. Иммунофлюоресцентное антигенное картирование является неотъемлемой частью комплексной морфологической диагностики ВБЭ, выступая промежуточным звеном между морфологическим подтверждением диагноза ВБЭ и таргетным поиском мутации молекулярно-генетическим методом.Врожденный буллезный эпидермолиз (ВБЭ) представляет собой обширную группу наследственных заболеваний кожи, дифференциальная диагностика которых сложна в связи с редкостью данной патологии и многообразием ее клинических проявлений. Определение типа ВБЭ позволяет оценить прогноз заболевания и облегчить проведение пренатальной диагностики. Цель — оптимизация морфологической диагностики различных видов ВБЭ. Материал и методы. Исследовано 28 биоптатов кожи от 14 пациентов с различными видами ВБЭ. Проводилось рутинное гистологическое исследование фрагментов кожи, взятых в области пузыря, и иммунофлюоресцентное антигенное картирование с применением непрямой реакции иммунофлюоресценции (нРИФ) с антителами к структурным белкам дермо-эпидермального соединения (α3-, β3- и γ2-цепям ламинина, кератинам 5 и 14, коллагенам VII и XVII типов, α6- и β4-субъединицам интегрина, десмоплакину, плектину, киндлину-1, плакофилину) видимо непораженной кожи. В качестве контроля при проведении нРИФ использовалась неизмененная кожа здоровых лиц, полученная при косметических операциях. Результаты. Метод иммунофлюоресцентного антигенного картирования позволил во всех случаях установить тип ВБЭ и в 86% — белок, нарушение продукции которого обусловило развитие заболевания. Заключение. Иммунофлюоресцентное антигенное картирование является неотъемлемой частью комплексной морфологической диагностики ВБЭ, выступая промежуточным звеном между морфологическим подтверждением диагноза ВБЭ и таргетным поиском мутации молекулярно-генетическим методом.

Triple negative breast cancer (TNBC) patients cannot be treated with endocrine therapy or targeted therapies due to lack of related receptors. These patients overexpress the epidermal growth factor receptor (EGFR), but are resistant to tyrosine kinase inhibitors (TKIs) and anti-EGFR therapies. Mechanisms suggested for resistance to TKIs include EGFR independence, mutations and alterations in EGFR and in its downstream signalling pathways. Ligand-induced endocytosis and degradation of EGFR play important roles in the downregulation of the EGFR signal suggesting that its activity could be regulated by targeting its trafficking. Evidence in normal cells showing that the scaffolding protein Na+/H+ exchanger regulatory factor 1 (NHERF1) can associate with EGFR to regulate its trafficking, led us to hypothesize that NHERF1 expression levels could regulate EGFR trafficking and functional expression in TNBC cells and, in this way, modulate its role in progression and response to treatment. We investigated the subcellular localization of NHERF1 and its interaction with EGFR in a metastatic basal like TNBC cell model, MDA-MB‑231, and the role of forced NHERF1 overexpression and/or stimulation with EGF on the sensitivity to EGFR specific TKI treatment with gefitinib. Stimulation with EGF induces an interaction of NHERF1 with EGFR to regulate its localization, degradation and function. NHERF1 overexpression is sufficient to drive its interaction with EGFR in non-stimulated conditions, inhibits EGFR degradation and increases its retention time in the plasma membrane. Importantly, NHERF1 overexpression strongly sensitized the cell to the pharmacological inhibition by gefitinib of EGFR-driven growth, motility and invadopodia-dependent ECM proteolysis. The further determination of how the NHERF1‑EGFR interaction is regulated may improve our understanding of TNBC resistance to the action of existing anticancer drugs.

Background Paraneoplastic pemphigus (PNP) serum preferentially reacts with periplakin and envoplakin, which are plakin family proteins localized to desmosomes and intermediate filaments. Recently, anti-periplakin antibodies were also detected in patients with idiopathic pulmonary fibrosis (IPF). Although previous epitope-mapping studies showed multiple epitopes in each protein, enzyme-linked immunosorbent assays have used several truncated, but not full-length, recombinant proteins. Methods This study aimed to produce full-length biotinylated recombinant proteins of periplakin and envoplakin for detection of autoantibodies by immunoprecipitation and ELISA. Serum from a PNP patient who had been confirmed as carrying anti-periplakin and anti-envoplakin antibodies in our previous study was used as a positive control. Sera from 15 patients with IPF were analyzed for both antibodies by immunoprecipitation and by ELISA. Results The PNP serum reacted strongly with the full-length recombinant proteins in immunoprecipitation and ELISA. Longitudinal serum samples from the PNP patient showed a clear decline of autoantibodies to both periplakin and envoplakin. None of the IPF sera showed both autoantibodies. Conclusions We found that the detection of anti-periplakin and anti-envoplakin antibodies using full-length recombinant proteins is useful immunoprecipitation and ELISA.

Novel therapies in autosomal dominant polycystic kidney disease (ADPKD) signal the need for markers of disease progression or response to therapy. This study aimed to identify disease-associated proteins in urinary extracellular vesicles (uEVs), which include exosomes, in patients with ADPKD. We performed quantitative proteomics on uEVs from healthy controls and patients with ADPKD using a labeled approach and then used a label-free approach with uEVs of different subjects (healthy controls versus patients with ADPKD versus patients with non-ADPKD CKD). In both experiments, 30 proteins were consistently more abundant (by two-fold or greater) in ADPKD-uEVs than in healthy- and CKD-uEVs. Of these proteins, we selected periplakin, envoplakin, villin-1, and complement C3 and C9 for confirmation because they were also significantly overrepresented in pathway analysis and were previously implicated in ADPKD pathogenesis. Immunoblotting confirmed higher abundances of the selected proteins in uEVs from three independent groups of patients with ADPKD. Whereas uEVs of young patients with ADPKD and preserved kidney function already had higher levels of complement, only uEVs of patients with advanced stages of ADPKD had increased levels of villin-1, periplakin, and envoplakin. Furthermore, all five proteins correlated positively with total kidney volume. Analysis in kidney tissue from mice with kidney-specific, tamoxifen-inducible Pkd1 deletion demonstrated higher expression in more severe stages of the disease and correlation with kidney weight for each protein of interest. In summary, proteomic analysis of uEVs identified plakins and complement as disease-associated proteins in ADPKD. These proteins are new candidates for evaluation as biomarkers or targets for therapy in ADPKD.

Periplakin (PPL), a member of the plakin protein family, has been reported to be down-expressed in urothelial carcinoma. The role of PPL in human colorectal cancer, however, remains largely unknown. Also little is known about the contribution of PPL to the malignant property of colorectal cancer and the intracellular function of PPL. In this study, we demonstrated that PPL was apparently down-expressed in colon carcinomas compared with normal and para-carcinoma tissues, which was correlated with the tumor size. Enforced expression of PPL in HT29 cells inhibited its proliferation evidenced by decreased expression of phosphorylated ERK and PCNA. Furthermore, PPL overexpression could reduce metastasis and epithelial-mesenchymal transition (EMT) of HT29 cells, with decreased expression of N-cadherin, Snail, Slug and α-SMA while increased expression of E-cadherin. On the contrary, the PPL knockdown could promote the cell proliferation, migratory, invasive and EMT ability of HT29 cells. Moreover, enforced expression of PPL induced G1/G0 cell cycle arrest, with decreased cyclin D1, p-Rb and increased expression of p27kib, which could be reversed by PPL knockdown. In addition, PPL overexpression inhibited the growth of colon cancer allograft in vivo. Taken together, acted as a tumor suppressor in colon cancer progression, PPL could be a new biomarker or potential therapeutic target in colon cancer.

Autoantibodies against N-terminal domains and linker subdomains of envoplakin (EVPL) and periplakin (PPL) were frequently detected in sera of paraneoplastic pemphigus(PNP) patients.To further investigate finer epitopes of EVPL and PPL, and evaluate their associations with clinical aspects of PNP.We produced 12 overlapping truncated fragments of these regions in Escherichia coli, and measured their reactivities to sera of 65 PNP patients and 50 healthy volunteers by enzyme-linked immunosorbent assays (ELISA). Then appropriate statistics were performed to evaluate the correlation between antibodies against different fragments and clinical information of patients.EVPL-N1 (aa1-141) and EVPL-L3 (aa1684-1784) were recognized by PNP sera at the same sensitivity of 75.38% (49/65) with specificities of 98% and 92%, respectively. Although neoplasm types were not associated with any fragment, the ELISA of these fragments and indirect immunofluorescence on rat bladder complemented each other in detecting PNP. Meanwhile, levels of autoantibodies against EVPL-N3 were elevated with PNP accompanied with bronchiolitis obliterans or presented with lichen planus-like lesions (P0.05). No influence of autoantibodies against any fragments on prognosis of the patients was observed by Cox regression test, though antibodies against some fragments were higher in the dead patients.The study proved antigenic epitopes were mainly concentrated on EVPL-N1 and EVPL-L3 in PNP. Autoantibodies against EVPL-N3 might associate with those patients accompanied with bronchiolitis obliterans or presented with lichen planus-like lesions.

Paraneoplastic pemphigus (PNP) is a rare, life-threatening, autoimmune, mucocutaneous blistering disease associated with neoplasia. Both humoral and cellular immunity are involved in the pathogenesis of PNP. Characteristically, PNP has a diverse spectrum of clinical and immunopathological features. We retrospectively analyzed 12 Korean patients with PNP who were diagnosed between 1993 and 2011. We performed analysis of the clinical features, clinical outcomes, underlying neoplasia, histological features and laboratory findings. All of the patients except one had severe mucosal involvement. Two patients had only mucosal lesions but no cutaneous involvement was observed. Erythema multiforme or lichen planus-like eruptions rather than bullous lesions were more commonly observed skin rashes. The most common histological features were interface dermatitis and apoptotic keratinocytes. There were associated hematological-related neoplasms in 11 patients, with Castleman's disease (n = 4) as the most frequent. Twelve patients were followed for 5-148 months (mean, 43.0). The prognosis depended on the nature of the underlying neoplasm. Six patients died due to respiratory failure (n = 3), postoperative septicemia (n = 1), lymphoma (n = 1) and sarcomatosis (n = 1). The 2-year survival rate was 50.0%, and the median survival period after diagnosis was 21.0 months. Immunoblotting was performed in 12 patients and autoantibodies to plakins were detected in 11 patients. The results of this study demonstrated the clinical, histological and immunological diversity of PNP. Widely accepted diagnostic criteria that account for the diversity of PNP are needed.

Objective The aim of this study was to investigate the relationship between membrane cytoskeleton linker protein Ezrin and CD44v6, iNOS, Ki-67, and clinicopathologic characteristics, and the prognostic significance of Ezrin expression in salivary gland adenoid cystic carcinoma (SACC). Study design Immunohistochemistry and reverse-transcription polymerase chain reaction were used to quantify the expression of Ezrin, CD44v6, inducible nitric oxide synthase (iNOS), and Ki-67 in 75 primary SACCs, 25 tumor-free salivary tissues, and 2 SACC cell lines (ACC-M and ACC-2). Survival analysis was performed to find the prognostic significance of Ezrin expression. Results Expressions of Ezrin, CD44v6, iNOS, and Ki-67 in SACC tissues, especially with distant metastasis, were significantly higher than in tumor-free tissues. Ezrin mRNA and protein levels in ACC-M cells were significantly higher than in ACC-2 cells. Ezrin, CD44v6, iNOS, and Ki-67 expressions were significantly higher in solid pattern than in cribriform and tubular patterns. Ezrin and its partners, CD44v6, iNOS, and Ki-67, were significantly related to tumor size, clinical stage, perineural and vascular invasion, and recurrence. Furthermore, Ezrin had an independent prognostic effect on overall survival. Conclusions The increased expression of Ezrin and its partners, CD44v6, iNOS, and Ki-67, in SACC correlated with histologic patterns, may play a role in distant metastasis, and might indicate poor clinical outcome.

The tyrosine phosphorylation of nephrin is reported to regulate podocyte morphology via the Nck adaptor proteins. The Pak family of kinases are regulators of the actin cytoskeleton and are recruited to the plasma membrane via Nck. Here, we investigated the role of Pak in podocyte morphology. Pak1/2 were expressed in cultured podocytes. In mouse podocytes, Pak2 was predominantly phosphorylated, concentrated at the tips of the cellular processes, and its expression and/or phosphorylation were further increased when differentiated. Overexpression of rat nephrin in podocytes increased Pak1/2 phosphorylation, which was abolished when the Nck binding sites were mutated. Furthermore, dominant-negative Nck constructs blocked the Pak1 phosphorylation induced by antibody-mediated cross linking of nephrin. Transient transfection of constitutively kinase-active Pak1 into differentiated mouse podocytes decreased stress fibers, increased cortical F-actin, and extended the cellular processes, whereas kinase-dead mutant, kinase inhibitory construct, and Pak2 knockdown by shRNA had the opposite effect. In a rat model of puromycin aminonucleoside nephrosis, Pak1/2 phosphorylation was decreased in glomeruli, concomitantly with a decrease of nephrin tyrosine phosphorylation. These results suggest that Pak contributes to remodeling of the actin cytoskeleton in podocytes. Disturbed nephrin-Nck-Pak interaction may contribute to abnormal morphology of podocytes and proteinuria.

Bullous pemphigoid is an autoimmune subepidermal blistering disease associated with autoantibodies against BP180 and BP230. We report herein a rare case of bullous pemphigoid with newly formed annular erythematous lesions when bullous skin lesions were in remission. Various immunological studies revealed immunoglobulin (Ig)A antibodies against desmoglein 1, envoplakin, periplakin and BP230 in addition to IgG antibodies against BP180 and BP230. These clinical and immunological changes in a patient are a rare event, suggesting an epitope-spreading phenomenon.

Desmosomes are patch-like intercellular adhering junctions ("maculae adherentes"), which, in concert with the related adherens junctions, provide the mechanical strength to intercellular adhesion. Therefore, it is not surprising that desmosomes are abundant in tissues subjected to significant mechanical stress such as stratified epithelia and myocardium. Desmosomal adhesion is based on the Ca(2+)-dependent, homo- and heterophilic transinteraction of cadherin-type adhesion molecules. Desmosomal cadherins are anchored to the intermediate filament cytoskeleton by adaptor proteins of the armadillo and plakin families. Desmosomes are dynamic structures subjected to regulation and are therefore targets of signalling pathways, which control their molecular composition and adhesive properties. Moreover, evidence is emerging that desmosomal components themselves take part in outside-in signalling under physiologic and pathologic conditions. Disturbed desmosomal adhesion contributes to the pathogenesis of a number of diseases such as pemphigus, which is caused by autoantibodies against desmosomal cadherins. Beside pemphigus, desmosome-associated diseases are caused by other mechanisms such as genetic defects or bacterial toxins. Because most of these diseases affect the skin, desmosomes are interesting not only for cell biologists who are inspired by their complex structure and molecular composition, but also for clinical physicians who are confronted with patients suffering from severe blistering skin diseases such as pemphigus. To develop disease-specific therapeutic approaches, more insights into the molecular composition and regulation of desmosomes are required.

HS1 complexes with cytoskeleton adapters in normal and malignant chronic lymphocytic leukemia B cells

A paraneoplasticus pemphigus malignus vagy benignus tumorokhoz tarsulo autoimmun holyagos megbetegedes diagnosztikus es immunologiai kriteriumait 1990-ben fektette le Anhalt . Klinikailag sulyos, fajdalmas, melyre terjedő bőr- es nyalkahartyatunetek jellemzik. A bőrtunetek polimorf jellegűek, altalaban dominal a holyagkepződes. Egyes esetekben, az un. „graft-versus-host-disease” formakban előfordul, hogy kizarolag papulosus, lichenoid bőrtunetek eszlelhetők, holyagkepződes nincs, vagy csak kesőbb jelenik meg. Elsősorban ezen alcsoport betegeiben a bőr- es nyalkahartyatunetek mellett sulyos dyspnoet okozo pulmonalis erintettseg is kialakul, melynek hattereben bronchiolitis obliterans all. A paraneoplasticus pemphigus diagnosztikajaban alapvető fontossagu a bőr/nyalkahartyak direkt immunfluoreszcens, tovabba a szerum indirekt immunhisztologiai es immunoblot vizsgalata. Az eddig azonositott autoantigenek dontő tobbsege a plakincsalad tagja: envoplakin (210 kDa), periplakin (190 kDa), plectin (~500 kDa), desmoplakin I (250 kDa), desmoplakin II (210 kDa), bullosus pemphigoid antigen 1 (230 kDa). A plakinok mellett a desmosomalis cadherinek koze sorolt desmoglein 1 es 3 a bullosus pemphigoid antigen 2 (180 kDa), a desmocollin 2 es 3, tovabba egy meg nem azonositott, 170 kDa molekulatomegű transzmembran feherje szinten autoantigenje a korkepnek. A paraneoplasticus pemphigus nagy mortalitasu korkep, az esetek tobb mint 90%-aban halalos kimenetelű. A hatterben allo tumor eltavolitasa mellett a bazisterapia tovabbra is a nagy dozisu szisztemas szteroidkezeles, melyet citosztatikumok, immunmodulansok adasaval egeszitenek ki. Szoba jon ezenkivul plasmapheresis, plazmacsere, photopheresis, nagy dozisu intravenas immunglobulin es anti-CD20 monoklonalis antitest (rituximab) adasa is. | Paraneoplastic pemphigus is an autoimmune bullous skin disease induced by underlying malignant or benign neoplasias. The diagnostic and immunological criteria of the disease were characterized by Anhalt et al. in 1990. Clinical symptoms are variable, consisting of polymorphous blistering skin eruption and severe, painful mucocutaneous ulcerations. In a subset of patients, only papular lesions develop, resembling lichen planus, or graft-versus-host disease; in some cases blisters may develop later. Severe dyspnoe, progressive respiratory failure with clinical features of bronchiolitis obliterans is a rather frequent and severe complication. The diagnosis can be established with direct and indirect immunofluorescent studies and immunoblot analysis. The autoantigens identified to date include cytoplasmic proteins of the plakin gene family: envoplakin (210 kD), periplakin (190 kD), plectin (~500 kD), desmoplakin I (250 kD), desmoplakin II (210 kD) and bullous pemphigoid antigen 1 (230 kD). The desmosomal cadherins: desmogleins 1 and 3, and desmocollins 2 and 3, as well as bullous pemphigoid antigen 2 (180 kD) and an undetermined 170-kD transmembranous antigen are also target autoantigens in the disease. The mortality rate is more than 90 percent. Beside treatment of the underlying tumor, a combination of systemic steroids with immunomodulants, cytostatic drugs, plasmapheresis, plasma exchange, intravenous gammaglobulin, or anti-CD20 monoclonal antibody (rituximab) may be the most appropriate treatment.

Bullous Pemphigoid Antigen 1 (BPAG1) is a member of the plakin family of proteins. The plakins are multi-domain proteins that have been shown to interact with microtubules, actin filaments and intermediate filaments, as well as proteins found in cellular junctions. These interactions are mediated through different domains on the plakins. The interactions between plakins and components of specialized cell junctions such as desmosomes and hemidesmosomes are mediated through the so-called plakin domain, which is a common feature of the plakins. In this study, we report the crystal structure of a stable fragment from BPAG1, residues 226-448, defined by limited proteolysis of the whole plakin domain. The structure, determined by single-wavelength anomalous diffraction (SAD) phasing from a selenomethionine-substituted crystal at 3.0 Å resolution, reveals a tandem pair of triple helical bundles closely related to spectrin repeats. Based on this structure and analysis of sequence conservation, we propose that the architecture of plakin domains is defined by two pairs of spectrin repeats interrupted by a putative Src-Homology 3 (SH3) domain.

Since the immunochemical identification of the bullous pemphigoid antigen 230 (BP230) as one of the major target autoantigens of bullous pemphigoid (BP) in 1981, our understanding of this protein has significantly increased. Cloning of its gene, development and characterization of animal models with engineered gene mutations or spontaneous mouse mutations have revealed an unexpected complexity of the gene encoding BP230. The latter, now called dystonin (DST), is composed of at least 100 exons and gives rise to three major isoforms, an epithelial, a neuronal and a muscular isoform, named BPAG1e (corresponding to the original BP230), BPAG1a and BPAG1b, respectively. The various BPAG1 isoforms play a key role in fundamental processes, such as cell adhesion, cytoskeleton organization, and cell migration. Genetic defects of BPAG1 isoforms are the culprits of epidermolysis bullosa and complex, devastating neurological diseases. In this review, we summarize recent advances of our knowledge about several BPAG1 isoforms, their role in various biological processes and in human diseases.

Sera from paraneoplastic pemphigus (PNP) immunoprecipitate multiple antigens from human epidermal protein extract. In this study, we further characterized the autoantibodies in 12 PNP sera. Immunoblotting using recombinant linker subdomains of envoplakin, periplakin, desmoplakin, and bullous pemphigoid antigen I found that 11 of the 12 sera recognized linker subdomains of envoplakin and periplakin. We then synthesized 12 peptides covering the linker subdomain of envoplakin for ELISA. One of the peptides, peptide no. 8, was recognized by nine out of the 12 sera with a higher affinity. A method of ligand–receptor binding assay was designed and performed using this peptide labeled with fluorescence as the ligand. Peptide no. 8 bound to CD20+ cells in Castleman's tumors from the patients whose sera were positive to this peptide by ELISA. Our data suggest that the linker subdomain of plakin proteins may be one of the major areas recognized by PNP autoantibodies, and epitopes in the linker subdomain of envoplakin recognized by PNP autoantibodies with a high affinity are dispersed in several areas and are variable among PNP patients. We also demonstrate that B-lymphocyte clones specifically reacting to epidermal proteins exist in Castleman's tumors from PNP.

Recent advances in two-dimensional electrophoresis (2-DE) such as fluorescent 2-D differential gel electrophoresis (2-D DIGE) has made it possible to detect and quantitate the critical changes involved in disease pathogenesis. We have previously identified novel proteins with altered expression in primary colorectal cancer using agarose 2-DE that has a higher loading capacity than immobilized pH gradient gel. The aim of this study is to identify novel proteins with altered expression in primary esophageal cancer using the powerful method of agarose 2-DE and agarose 2-D DIGE. Excised tissues from 12 patients of primary esophageal cancer were obtained. Proteins with altered expression between cancer and adjacent non-cancer tissues were analyzed by agarose 2-D DIGE and identified by mass spectrometry. Thirty-three proteins out of 74 spots with altered expression in tumors were identified. Among them, a 195-kDa protein, periplakin, was significantly downregulated in esophageal cancer, which was confirmed by immunoblotting. Immunohistochemistry showed that periplakin was mainly localized at cell-cell boundaries in normal epithelium and dysplastic lesions, while it disappeared from cell boundaries, shifted to cytoplasm, in early cancers and scarcely expressed in advanced cancers. These results suggest that periplakin could be a useful marker for detection of early esophageal cancer and evaluation of tumor progression.

Plectin is one of the largest and most versatile cytolinker proteins known. Cloned and sequenced in 1991, it was later shown to have nonsense mutations in recessive epidermolysis bullosa with muscular dystrophy. A dominant mutation in the gene was found to cause epidermolysis bullosa simplex Ogna without muscular dystrophy. Here we report the DNA sequencing of the plectin gene (PLEC1) in a Dutch family originally described in 1972 as having epidermolysis bullosa with muscular dystrophy. The results revealed homozygosity for a new plectin nonsense mutation at position 13187 and its specific 8q24 marker haplotype profile. Western blotting of cultured fibroblasts and immunofluorescence microscopy of skin biopsy confirm that the plectin protein expression is grossly reduced or absent. A summary of the life-long clinical course of the two affected brothers homozygous for the new E1914X mutation is given.

Periplakin forms part of the scaffold onto which the epidermal cornified envelope is assembled. The NH2-terminal 133 amino acids mediate association with the plasma membrane and bind a novel protein, kazrin. Kazrin is highly conserved and lacks homology to any known protein. There are four alternatively spliced transcripts, encoding three proteins with different NH2 termini. Kazrin is expressed in all layers of stratified squamous epithelia; it becomes membrane associated in the suprabasal layers, coincident with up-regulation of periplakin, and is incorporated into the cornified envelope of cultured keratinocytes. Kazrin colocalizes with periplakin and desmoplakin at desmosomes and with periplakin at the interdesmosomal plasma membrane, but its subcellular distribution is independent of periplakin. On transfection, all three kazrin isoforms have similar subcellular distributions. We conclude that kazrin is a novel component of desmosomes that associates with periplakin.

The anucleate prismoid fiber cells of the eye lens are densely packed to form a tissue in which the plasma membranes and their associated cytoplasmic coat form a single giant cell-cell adhesive complex, the cortex adhaerens. Using biochemical and immunoprecipitation methods in various species (cow, pig, rat), in combination with immunolocalization microscopy, we have identified two different major kinds of cortical complex. In one, the transmembrane glycoproteins N-cadherin and cadherin-11 [which also occur in heterotypic (`mixed') complexes] are associated with α- and β-catenin, plakoglobin (proportions variable among species), p120ctn and vinculin. The other complex contains ezrin, periplakin, periaxin and desmoyokin (and so is called the EPPD complex), usually together with moesin, spectrin(s) and plectin. In sections through lens fiber tissue, the short sides of the lens fiber hexagons appear to be enriched in the cadherin-based complexes, whereas the EPPD complexes also occur on the long sides. Moreover, high resolution double-label fluorescence microscopy has revealed, on the short sides, a finer, almost regular mosaicism of blocks comprising the cadherin-based, catenin-containing complexes, alternating with patches formed by the EPPD complexes. The latter, a new type of junctional plaque ensemble of proteins hitherto known only from certain other cell types, must be added to the list of major lens cortex proteins. We here discuss its possible functional importance for the maintenance of lens structure and functions, notably clear and sharp vision.

SummaryBackground Paraneoplastic pemphigus (PNP) is an autoimmune mucocutaneous disease associated with specific B-cell lymphoproliferative neoplasms. There has been an increasing number of individual reports in the childhood and adolescent population. Objectives To examine the clinical and immunopathological features of PNP occurring in children and adolescents. Patients and methods We analysed the clinical and immunopathological findings of 14 patients under the age of 18 years with a confirmed diagnosis of PNP. Sera from all patients were analysed by indirect immunofluorescence (IF) and immunoprecipitation for plakin autoantibodies, immunoblotting for detection of plectin autoantibodies, and enzyme-linked immunosorbent assay (ELISA) for the detection of desmoglein (Dsg) 1 and Dsg3 autoantibodies. Results Severe oral mucositis was observed in all patients, and lichenoid cutaneous lesions in eight of 14 patients. The average age at presentation was 13 years. Striking findings included: pulmonary destruction leading to bronchiolitis obliterans in 10 patients, association with Castleman's disease in 12 patients, and a fatal outcome in 10 patients. The underlying neoplasm was occult in 10 patients. Histological findings include lichenoid and interface dermatitis with variable intraepithelial acantholysis. Deposition of IgG and C3 in the mouth and skin by direct IF was not found in some cases, but indirect IF detected IgG autoantibodies in all cases. Immunoprecipitation revealed IgG autoantibodies against desmoplakin I, envoplakin and periplakin in all cases, and against desmoplakin II and the 170-kDa antigen in 13 and 10 patients, respectively. Dsg3 and Dsg1 autoantibodies were present in 10 and three patients, respectively, and plectin autoantibodies in 13 patients. Conclusions PNP in children and adolescents is most often a presenting sign of occult Castleman's disease. It presents with severe oral mucositis and cutaneous lichenoid lesions. Serum autoantibodies against plakin proteins were the most constant diagnostic markers. Pulmonary injury appears to account for the very high mortality rates observed.

Plectin is one of the largest and most versatile cytolinker proteins known. In basal keratinocytes it links the intermediate filament network to cell membrane-associated hemidesmosomes. Several mutations in its gene have been identified that lead to the recessive disease epidermolysis bullosa with muscular dystrophy. We report here a mutation that leads to a dominant form of the disease, epidermolysis bullosa simplex Ogna. We found that the epidermolysis bullosa simplex Ogna phenotype is due to a site-specific missense mutation within plectin's rod domain. Further, we show that epidermolysis bullosa simplex Ogna is not restricted to a single Norwegian kindred as previously believed. A German family with the phenotypic hallmarks of epidermolysis bullosa simplex Ogna was found to carry an identical de novo mutation. These two mutations arose about 200 y apart in time. Consistent with the absence of muscular symptoms in these patients, muscle biopsies from several epidermolysis bullosa simplex Ogna members of the Norwegian kindred showed normal staining patterns using antibodies to plectin. Skin changes in epidermolysis bullosa simplex Ogna patients are documented on the ultrastructural level.

The objective of this study was to determine periplakin expression in normal urothelium and bladder cancer tissues and the relationship to clinicopathological findings. Immunohistochemical staining for periplakin was carried out in 92 archival radical cystectomy specimens, with immunoreactivity being stratified on a 0-6 scale. Immunohistochemical staining for periplakin was shown to be significantly lower in bladder cancer tissues compared to non-cancerous tissues including inflammation,hyperplasia and normal urothelium. Loss of periplakin expression was associated with pathological stage (P=0.04). In multivariate Cox regression analysis, loss of periplakin expression and positive lymph node status were independent prognostic factors for cancer-specific survival (P=0.03 and 0.015; odds ratio=2.29 and 2.66; 95% confidence interval=1.085-4.814 and 1.214-5.845, respectively). This new molecular marker may aid in identifying and selecting bladder cancer patients undergoing radical cystectomy who may potentially benefit from neoadjuvant or adjuvant therapy.

The linker of nucleoskeleton and cytoskeleton (LINC) complex, composed of proteins within the inner and the outer nuclear membranes, connects the nuclear lamina to the cytoskeleton. The importance of this complex has been highlighted by the discovery of mutations in genes encoding LINC complex proteins, which cause skeletal or cardiac myopathies. Herein, this review summarizes structure, function, and interactions of major components of the LINC complex, highlights how mutations in these proteins may lead to cardiac disease, and outlines future challenges in the field.

Paraneoplastic pemphigus sera react with multiple plakin family proteins, among which only envoplakin and periplakin are constantly detected by immunoblotting using normal human epidermal extracts. Using bacterial expression vectors containing polymerase chain reaction-amplified cDNA, we have prepared variously truncated recombinant glutathione-S-transferase-fusion proteins of envoplakin and periplakin, which presented N-terminal, central and C-terminal domains of each protein, as well as the so-called C-terminal homologous domain of envoplakin and the junctional regions of these domains. By immunoblotting using these 11 recombinant proteins, we demonstrated that most of the 26 paraneoplastic pemphigus sera reacted very strongly with multiple recombinant proteins of envoplakin and periplakin, except for the C-terminal homologous domain of periplakin. We also examined the reactivity with these recombinant proteins of other blistering diseases, including pemphigus vulgaris, pemphigus foliaceus, and bullous pemphigoid, and found that a few nonparaneoplastic pemphigus sera showed a weak reactivity with some of the recombinant proteins. Interestingly, some sera showed relatively strong reactivity with the C-terminal homologous domain of periplakin to which paraneoplastic pemphigus sera reacted less frequently. These results indicate that, although nonparaneoplastic pemphigus sera occasionally show a weak reactivity with envoplakin and periplakin, the pathogenicity and the mechanism of antibody production in these cases may be different from those in paraneoplastic pemphigus.

Sera of patients with paraneoplastic pemphigus (PNP) characteristically immunoprecipitate five proteins, observations confirmed with the sera examined in this study. The proteins characterized thus far as autoantigens in PNP all belong to the plakin family of proteins and include desmoplakin, the 230 kDa bullous pemphigoid antigen, and envoplakin. The pattern of bands precipitated from metabolically labeled human keratinocyte extracts by each PNP serum was different, suggesting varying titers of antibodies against unique epitopes in various plakin family members. To further characterize this PNP antibody response, we produced fusion proteins of the homologous tail region of five plakin family members, including the recently cloned periplakin. Immunoblotting of equal amounts of each plakin tail-glutathione S-transferase fusion protein with PNP sera revealed a strong reaction with the envoplakin tail domain. Each sera also recognized periplakin, and certain sera recognized desmoplakin and plectin, and, weakly, bullous pemphigoid antigen 1. PNP sera were affinity purified with periplakin and envoplakin tail fusion proteins. Immunoprecipitation and immunoblotting with these affinity purified antibodies revealed shared as well as unique epitopes in the tail domains of these plakins. This study indicates that a homologous region in the carboxy-terminus of plakins, including the newly characterized periplakin, serves as an antigenic site in PNP.

The cornified envelope is a layer of transglutaminase cross-linked protein that is assembled under the plasma membrane of keratinocytes in the outermost layers of the epidermis. We have determined the cDNA sequence of one of the proteins that becomes incorporated into the cornified envelope of cultured epidermal keratinocytes, a protein with an apparent molecular mass of 195 kD that is encoded by a mRNA with an estimated size of 6.3 kb. The protein is expressed in keratinizing and nonkeratinizing stratified squamous epithelia and in a number of other epithelia. Expression of the protein is upregulated during the terminal differentiation of epidermal keratinocytes in vivo and in culture. Immunogold electron microscopy was used to demonstrate an association of the 195-kD protein with the desmosomal plaque and with keratin filaments in the differentiated layers of the epidermis. Sequence analysis showed that the 195-kD protein is a member of the plakin family of proteins, to which envoplakin, desmoplakin, bullous pemphigoid antigen 1, and plectin belong. Envoplakin and the 195-kD protein coimmunoprecipitate. Analysis of their rod domain sequences suggests that the formation of both homodimers and heterodimers would be energetically favorable. Confocal immunofluorescent microscopy of cultured epidermal keratinocytes revealed that envoplakin and the 195-kD protein form a network radiating from desmosomes, and we speculate that the two proteins may provide a scaffolding onto which the cornified envelope is assembled. We propose to name the 195-kD protein periplakin.

Background: Pemphigus shows geographically variable characteristics. Objective: To study the clinical and immunologic characteristics of Indian pemphigus patients before and after treatment. Methods: Twenty-six Indian pemphigus patients were analyzed with regard to age, gender, clinical features, treatments and response, the results of histopathology, direct and indirect immunofluorescence (IF), enzyme-linked immunosorbent assay (ELISA), and immunoblot analyses. Results: There were 22 pemphigus vulgaris (PV) and 4 pemphigus foliaceus (PF) patients. Direct and indirect IF was positive in 95.8% and 56% of patients, respectively. Indices of ELISA were lower in our study. Immunoblot assays detected the 130 kDa desmoglein-3 in 10 PV patients and the 160 kDa desmoglein-1 in 1 PV patient; 190 kDa periplakin was unexpectedly detected in 8 patients. Conclusion: Indian pemphigus patients showed several unique characteristics, including younger population, predominance of PV, low ELISA indices, lower sensitivity of indirect IF and immunoblotting, and the presence of the 190 kDa periplakin in nearly one-third of patients.