RESUMO
Plakophilin 1 (PKP1) belongs to the desmosome family as an anchoring junction protein in cellular junctions. It localizes at the interface of the cell membrane and cytoplasm. Although PKP1 is a non-transmembrane protein, it may become associated with the cell membrane via transmembrane proteins such as desmocollins and desmogleins. Homozygous deletion of PKP1 results in ectodermal dysplasia-skin fragility syndrome (EDSF) and complete knockout of PKP1 in mice produces comparable symptoms to EDSF in humans, although mice do not survive more than 24 h. PKP1 is not limited to expression in desmosomal structures, but is rather widely expressed in cytoplasm and nucleus, where it assumes important cellular functions. This review will summarize distinct roles of PKP1 in the cell membrane, cytoplasm, and nucleus with an overview of relevant studies on its function in diverse types of cancer.
Assuntos
Carcinogênese , Neoplasias , Placofilinas , Humanos , Placofilinas/genética , Placofilinas/metabolismo , Animais , Carcinogênese/genética , Carcinogênese/metabolismo , Carcinogênese/patologia , Neoplasias/genética , Neoplasias/metabolismo , Neoplasias/patologia , Citoplasma/metabolismo , Membrana Celular/metabolismo , Núcleo Celular/metabolismo , Núcleo Celular/genética , Desmossomos/metabolismo , Desmossomos/genéticaRESUMO
Arrhythmogenic cardiomyopathy (ACM) is a rare genetic cardiac disease characterized by the progressive substitution of myocardium with fibro-fatty tissue. Clinically, ACM shows wide variability among patients; symptoms can include syncope and ventricular tachycardia but also sudden death, with the latter often being its sole manifestation. Approximately half of ACM patients have been found with variations in one or more genes encoding cardiac intercalated discs proteins; the most involved genes are plakophilin 2 (PKP2), desmoglein 2 (DSG2), and desmoplakin (DSP). Cardiac intercalated discs provide mechanical and electro-metabolic coupling among cardiomyocytes. Mechanical communication is guaranteed by the interaction of proteins of desmosomes and adheren junctions in the so-called area composita, whereas electro-metabolic coupling between adjacent cardiac cells depends on gap junctions. Although ACM has been first described almost thirty years ago, the pathogenic mechanism(s) leading to its development are still only partially known. Several studies with different animal models point to the involvement of the Wnt/ß-catenin signaling in combination with the Hippo pathway. Here, we present an overview about the existing murine models of ACM harboring variants in intercalated disc components with a particular focus on the underlying pathogenic mechanisms. Prospectively, mechanistic insights into the disease pathogenesis will lead to the development of effective targeted therapies for ACM.
Assuntos
Displasia Arritmogênica Ventricular Direita , Modelos Animais de Doenças , Animais , Humanos , Displasia Arritmogênica Ventricular Direita/genética , Displasia Arritmogênica Ventricular Direita/metabolismo , Displasia Arritmogênica Ventricular Direita/patologia , Placofilinas/genética , Placofilinas/metabolismo , Desmoplaquinas/genética , Desmoplaquinas/metabolismo , Via de Sinalização Wnt/genética , Desmogleína 2/genética , Desmogleína 2/metabolismo , Desmossomos/metabolismo , Desmossomos/genética , CamundongosRESUMO
Arrhythmogenic cardiomyopathy (ACM) is an inherited myocardial disease at risk of sudden death. Genetic testing impacts greatly in ACM diagnosis, but gene-disease associations have yet to be determined for the increasing number of genes included in clinical panels. Genetic variants evaluation was undertaken for the most relevant non-desmosomal disease genes. We retrospectively studied 320 unrelated Italian ACM patients, including 243 cases with predominant right-ventricular (ARVC) and 77 cases with predominant left-ventricular (ALVC) involvement, who did not carry pathogenic/likely pathogenic (P/LP) variants in desmosome-coding genes. The aim was to assess rare genetic variants in transmembrane protein 43 (TMEM43), desmin (DES), phospholamban (PLN), filamin c (FLNC), cadherin 2 (CDH2), and tight junction protein 1 (TJP1), based on current adjudication guidelines and reappraisal on reported literature data. Thirty-five rare genetic variants, including 23 (64%) P/LP, were identified in 39 patients (16/243 ARVC; 23/77 ALVC): 22 FLNC, 9 DES, 2 TMEM43, and 2 CDH2. No P/LP variants were found in PLN and TJP1 genes. Gene-based burden analysis, including P/LP variants reported in literature, showed significant enrichment for TMEM43 (3.79-fold), DES (10.31-fold), PLN (117.8-fold) and FLNC (107-fold). A non-desmosomal rare genetic variant is found in a minority of ARVC patients but in about one third of ALVC patients; as such, clinical decision-making should be driven by genes with robust evidence. More than two thirds of non-desmosomal P/LP variants occur in FLNC.
Assuntos
Displasia Arritmogênica Ventricular Direita , Humanos , Displasia Arritmogênica Ventricular Direita/genética , Feminino , Masculino , Adulto , Pessoa de Meia-Idade , Proteínas de Membrana/genética , Caderinas/genética , Desmossomos/genética , Desmossomos/metabolismo , Predisposição Genética para Doença , Variação Genética , Filaminas/genética , Estudos Retrospectivos , Itália , Proteínas de Ligação ao Cálcio/genética , Antígenos CD/genéticaRESUMO
Arrhythmogenic cardiomyopathy (ACM) is an inherited cardiac disease characterized by fibrofatty replacement of the myocardium. Deleterious variants in desmosomal genes are the main cause of ACM and lead to common and gene-specific molecular alterations, which are not yet fully understood. This article presents the first systematic in vitro study describing gene and protein expression alterations in desmosomes, electrical conduction-related genes, and genes involved in fibrosis and adipogenesis. Moreover, molecular and functional alterations in calcium handling were also characterized. This study was performed d with HL1 cells with homozygous knockouts of three of the most frequently mutated desmosomal genes in ACM: PKP2, DSG2, and DSC2 (generated by CRISPR/Cas9). Moreover, knockout and N-truncated clones of DSP were also included. Our results showed functional alterations in calcium handling, a slower calcium re-uptake was observed in the absence of PKP2, DSG2, and DSC2, and the DSP knockout clone showed a more rapid re-uptake. We propose that the described functional alterations of the calcium handling genes may be explained by mRNA expression levels of ANK2, CASQ2, ATP2A2, RYR2, and PLN. In conclusion, the loss of desmosomal genes provokes alterations in calcium handling, potentially contributing to the development of arrhythmogenic events in ACM.
Assuntos
Displasia Arritmogênica Ventricular Direita , Cálcio , Humanos , Displasia Arritmogênica Ventricular Direita/genética , Displasia Arritmogênica Ventricular Direita/metabolismo , Desmossomos/genética , Desmossomos/metabolismo , Miocárdio/metabolismo , CoraçãoRESUMO
Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a fatal genetic heart disease characterized by cardiac arrhythmias, in which fibrofatty deposition leads to heart failure, with no effective treatments. Plakophilin 2 (PKP2) is the most frequently mutated gene in ARVC, and although altered RNA splicing has been implicated, there are no models to study its effect and therapeutics. Here, we generate a mouse model harboring a PKP2 mutation (IVS10-1G>C) affecting RNA splicing, recapitulating ARVC features and sudden death starting at 4 weeks. Administering AAV-PKP2 gene therapy (adeno-associated viral therapy to drive cardiac expression of PKP2) to neonatal mice restored PKP2 protein levels, completely preventing cardiac desmosomal and pathological deficits associated with ARVC, ensuring 100% survival of mice up to 6 months. Late-stage AAV-PKP2 administration rescued desmosomal protein deficits and reduced pathological deficits including improved cardiac function in adult mice, resulting in 100% survival up to 4 months. We suggest that AAV-PKP2 gene therapy holds promise for circumventing ARVC associated with PKP2 mutations, including splice site mutations.
Assuntos
Displasia Arritmogênica Ventricular Direita , Terapia Genética , Placofilinas , Animais , Humanos , Masculino , Camundongos , Animais Recém-Nascidos , Displasia Arritmogênica Ventricular Direita/genética , Displasia Arritmogênica Ventricular Direita/terapia , Dependovirus/genética , Desmossomos/genética , Desmossomos/metabolismo , Modelos Animais de Doenças , Predisposição Genética para Doença , Terapia Genética/métodos , Vetores Genéticos/administração & dosagem , Camundongos Endogâmicos C57BL , Mutação , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , Fenótipo , Placofilinas/genética , Splicing de RNA/genéticaRESUMO
Desmosomes are essential structures for ensuring tissue functions, and their deregulation is involved in the development of colorectal cancer (CRC). JUP (γ-catenin) is a desmosome adhesion component that also acts as a signaling hub, suggesting its potential involvement in CRC progression. In this context, we recently demonstrated that miR-195-5p regulated JUP and desmosome cadherins expression. In addition, miR-195-5p gain of function indirectly modulated the expression of key effectors of the Wnt pathway involved in JUP-dependent signaling. Here, our purpose was to demonstrate the aberrant expression of miR-195-5p and JUP in CRC patients and to functionally characterize the role of miR-195-5p in the regulation of desmosome function. First, we showed that miR-195-5p was downregulated in CRC tumors compared to adjacent normal tissue. Then, we demonstrated that JUP expression was significantly increased in CRC tissues compared to adjacent normal tissues. The effects of miR-195-5p on CRC progression were assessed using in vitro transient transfection experiments and in vivo miRNA administration. Increased miR-195-5p in colonic epithelial cells strongly inhibits cell proliferation, viability, and invasion via JUP. In vivo gain of function of miR-195-5p reduced the numbers and sizes of tumors and significantly ameliorated the histopathological changes typical of CRC. In conclusion, our findings indicate a potential pharmacological target based on miR-195-5p replacement as a new therapeutic approach in CRC.
Assuntos
Neoplasias do Colo , MicroRNAs , Humanos , Desmossomos/genética , gama Catenina , Regulação para Baixo/genética , Neoplasias do Colo/genética , MicroRNAs/genéticaRESUMO
Arrhythmogenic cardiomyopathy with right dominant form (ACR) is a rare heritable cardiac cardiomyopathy disorder associated with sudden cardiac death. Pathogenic variants (PVs) in desmosomal genes have been causally related to ACR in 40% of cases. Other genes encoding nondesmosomal proteins have been described in ACR, but their contribution in this pathology is still debated. A panel of 71 genes associated with inherited cardiopathies was screened in an ACR population of 172 probands and 856 individuals from the general population. PVs and uncertain significance variants (VUS) have been identified in 36% and 18.6% of patients, respectively. Among the cardiopathy-associated genes, burden tests show a significant enrichment in PV and VUS only for desmosomal genes PKP2 (plakophilin-2), DSP (desmoplakin), DSC2 (desmocollin-2), and DSG2 (desmoglein-2). Importantly, VUS may account for 15% of ACR cases and should then be considered for molecular diagnosis. Among the other genes, no evidence of enrichment was detected, suggesting an extreme caution in the interpretation of these genetic variations without associated functional or segregation data. Genotype-phenotype correlation points to (1) a more severe and earlier onset of the disease in PV and VUS carriers, underlying the importance to carry out presymptomatic diagnosis in relatives and (2) to a more prevalent left ventricular dysfunction in DSP variant carriers.
Assuntos
Displasia Arritmogênica Ventricular Direita , Displasia Arritmogênica Ventricular Direita/diagnóstico , Displasia Arritmogênica Ventricular Direita/genética , Displasia Arritmogênica Ventricular Direita/metabolismo , Desmossomos/genética , Desmossomos/metabolismo , Estudos de Associação Genética , Heterozigoto , Humanos , Placofilinas/genética , Placofilinas/metabolismoRESUMO
BACKGROUND: Deleterious rare variants in genes encoding desmosome proteins have been identified as the essential basis of arrhythmogenic cardiomyopathy (ACM) and detected in dilated cardiomyopathy, but the relationship between deleterious rare desmosomal variants and hypertrophic cardiomyopathy (HCM) remains unknown. METHODS: Whole exome sequencing was performed in 1000 patients with HCM and 761 non-HCM controls to search for deleterious rare variants in genes encoding desmosomal proteins including PKP2, JUP, DSC2, DSG2, and DSP. Clinical phenotypes were assessed in patients with HCM, and patients with deleterious rare desmosomal variants underwent evaluation of ACM revised Task Force Criteria. RESULTS: A total of 27 deleterious rare desmosomal variants were present in 24 (2.4%) patients with HCM and 5 (0.66%) controls. The variants were more prevalent in the patients with HCM than in the controls (P = 0.004). The majority of patients possessing deleterious rare desmosomal variants could not be diagnosed as ACM. Moreover, the patients with deleterious rare desmosomal variants possessed several distinctive clinical features compared with patients without such variants, including a higher incidence of nonsustained ventricular tachycardia (29.2% vs 4.5%, P < 0.001), left bundle branch block (33.3% vs 1.6%, P < 0.001), and right ventricular involvement for an HCM phenotype (29.2% vs 0.30%, P < 0.001). CONCLUSIONS: We screened deleterious rare desmosomal variants in a large HCM case-control cohort and found deleterious rare desmosomal variants can be relevant to HCM. Moreover, our data indicated deleterious rare desmosomal variants were associated with distinctive clinical features of HCM. These findings require validation in other HCM cohorts.
Assuntos
Cardiomiopatia Hipertrófica/genética , DNA/genética , Desmossomos/genética , Mutação , Função Ventricular Direita/fisiologia , Adulto , Cardiomiopatia Hipertrófica/diagnóstico , Cardiomiopatia Hipertrófica/fisiopatologia , Análise Mutacional de DNA , Desmossomos/metabolismo , Eletrocardiografia Ambulatorial/métodos , Feminino , Seguimentos , Predisposição Genética para Doença , Humanos , Imagem Cinética por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Linhagem , Fenótipo , Estudos Retrospectivos , Sequenciamento Completo do Genoma/métodosRESUMO
Desmoglein 1 (Dsg1) is a cadherin restricted to stratified tissues of terrestrial vertebrates, which serve as essential physical and immune barriers. Dsg1 loss-of-function mutations in humans result in skin lesions and multiple allergies, and isolated patient keratinocytes exhibit increased proallergic cytokine expression. However, the mechanism by which genetic deficiency of Dsg1 causes chronic inflammation is unknown. To determine the systemic response to Dsg1 loss, we deleted the 3 tandem Dsg1 genes in mice. Whole transcriptome analysis of embryonic Dsg1-/- skin showed a delay in expression of adhesion/differentiation/keratinization genes at E17.5, a subset of which recovered or increased by E18.5. Comparing epidermal transcriptomes from Dsg1-deficient mice and humans revealed a shared IL-17-skewed inflammatory signature. Although the impaired intercellular adhesion observed in Dsg1-/- mice resembles that resulting from anti-Dsg1 pemphigus foliaceus antibodies, pemphigus skin lesions exhibit a weaker IL-17 signature. Consistent with the clinical importance of these findings, treatment of 2 Dsg1-deficient patients with an IL-12/IL-23 antagonist originally developed for psoriasis resulted in improvement of skin lesions. Thus, beyond impairing the physical barrier, loss of Dsg1 function through gene mutation results in a psoriatic-like inflammatory signature before birth, and treatment with a targeted therapy significantly improved skin lesions in patients.
Assuntos
Desmogleína 1/imunologia , Desmossomos/imunologia , Queratinócitos/imunologia , Pênfigo/imunologia , Células Th17/imunologia , Animais , Desmogleína 1/genética , Desmossomos/genética , Camundongos , Pênfigo/genéticaRESUMO
Single gene disorders are ideally suited to establish robust genotypeâphenotype correlations and provide excellent opportunities to understand molecular pathomechanisms with relevance to complex disorders. The observation that patients diagnosed with the same causative mutation can present with phenotypic disease variability illustrates the significant role of disease modifiers and warns against oversimplification. In a new article in the Journal of Investigative Dermatology, Zimmer et al. (2021) analyze two mutations located in the desmoglein (DSG) 1 transmembrane domain (TMD) and find that both mutants fail to assemble into desmosomes owing to reduced membrane trafficking and lipid raft targeting. One mutation maintained normal protein expression levels and turnover relative to those of wild-type (WT) DSG1, and behaved as a dominant negative. The second mutant showed reduced stability and increased turnover compared with WT DSG1 as well as reduced desmosome size and abundance. A full understanding of the TMD of DSG1 requires cell biological approaches, underscoring the value of cell biology in biomedical research in general.
Assuntos
Desmogleína 1 , Desmossomos , Desmogleína 1/genética , Desmossomos/genética , Humanos , Microdomínios da Membrana , MutaçãoRESUMO
The vast majority of breast cancer-associated deaths are due to metastatic spread of cancer cells, a process aided by epithelial-to-mesenchymal transition (EMT). Mounting evidence has indicated that long non-coding RNAs (lncRNAs) also contribute to tumor progression. We report the identification of 114 novel lncRNAs that change their expression during TGFß-induced EMT in murine breast cancer cells (referred to as EMT-associated transcripts; ETs). Of these, the ET-20 gene localizes in antisense orientation within the tenascin C (Tnc) gene locus. TNC is an extracellular matrix protein that is critical for EMT and metastasis formation. Both ET-20 and Tnc are regulated by the EMT master transcription factor Sox4. Notably, ablation of ET-20 lncRNA effectively blocks Tnc expression and with it EMT. Mechanistically, ET-20 interacts with desmosomal proteins, thereby impairing epithelial desmosomes and promoting EMT. A short transcript variant of ET-20 is shown to be upregulated in invasive human breast cancer cell lines, where it also promotes EMT. Targeting ET-20 appears to be a therapeutically attractive lead to restrain EMT and breast cancer metastasis in addition to its potential utility as a biomarker for invasive breast cancer.
Assuntos
Neoplasias da Mama , RNA Longo não Codificante , Animais , Neoplasias da Mama/genética , Linhagem Celular Tumoral , Desmossomos/genética , Transição Epitelial-Mesenquimal/genética , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Camundongos , Invasividade Neoplásica/genética , RNA Longo não Codificante/genética , Fatores de Transcrição SOXCRESUMO
Desmosomes (DSMs), together with adherens junctions (AJs) and tight junctions (TJs), constitute the apical cell junctional complex (AJC). While the importance of the apical and basolateral polarity machinery in the organization of AJs and TJs is well established, how DSMs are positioned within the AJC is not understood. Here we use highly polarized DLD1 cells as a model to address how DSMs integrate into the AJC. We found that knockout (KO) of the desmosomal ARM protein Pkp3, but not other major DSM proteins, uncouples DSMs from the AJC without blocking DSM assembly. DLD1 cells also exhibit a prominent extraDSM pool of Pkp3, concentrated in tricellular (tC) contacts. Probing distinct apicobasal polarity pathways revealed that neither the DSM's association with AJC nor the extraDSM pool of Pkp3 are abolished in cells with defects in Scrib module proteins responsible for basolateral membrane development. However, a loss of the apical polarity protein, Par3, completely eliminates the extraDSM pool of Pkp3 and disrupts AJC localization of desmosomes, dispersing these junctions along the entire length of cell-cell contacts. Our data are consistent with a model whereby Par3 facilitates DSM assembly within the AJC, controlling the availability of an assembly competent pool of Pkp3 stored in tC contacts.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Junções Aderentes/metabolismo , Proteínas de Ciclo Celular/metabolismo , Desmossomos/metabolismo , Placofilinas/metabolismo , Junções Íntimas/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Junções Aderentes/genética , Animais , Células CACO-2 , Comunicação Celular/genética , Proteínas de Ciclo Celular/genética , Linhagem Celular Tumoral , Polaridade Celular/genética , Células Cultivadas , Desmossomos/genética , Cães , Células Epiteliais/metabolismo , Técnicas de Inativação de Genes , Humanos , Células Madin Darby de Rim Canino , Microscopia de Fluorescência/métodos , Placofilinas/genética , Junções Íntimas/genéticaRESUMO
Dysregulated protein degradative pathways are increasingly recognized as mediators of human disease. This mechanism may have particular relevance to desmosomal proteins that play critical structural roles in both tissue architecture and cell-cell communication, as destabilization/breakdown of the desmosomal proteome is a hallmark of genetic-based desmosomal-targeted diseases, such as the cardiac disease arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C). However, no information exists on whether there are resident proteins that regulate desmosomal proteome homeostasis. Here, we uncovered a cardiac constitutive photomorphogenesis 9 (COP9) desmosomal resident protein complex, composed of subunit 6 of the COP9 signalosome (CSN6), that enzymatically restricted neddylation and targeted desmosomal proteome degradation. CSN6 binding, localization, levels, and function were affected in hearts of classic mouse and human models of ARVD/C affected by desmosomal loss and mutations, respectively. Loss of desmosomal proteome degradation control due to junctional reduction/loss of CSN6 and human desmosomal mutations destabilizing junctional CSN6 were also sufficient to trigger ARVD/C in mice. We identified a desmosomal resident regulatory complex that restricted desmosomal proteome degradation and disease.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Displasia Arritmogênica Ventricular Direita/metabolismo , Complexo do Signalossomo COP9/metabolismo , Desmossomos/metabolismo , Proteólise , Proteoma/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Displasia Arritmogênica Ventricular Direita/genética , Complexo do Signalossomo COP9/genética , Desmossomos/genética , Desmossomos/patologia , Modelos Animais de Doenças , Feminino , Humanos , Masculino , Camundongos , Camundongos Knockout , Proteoma/genéticaRESUMO
BACKGROUND: Genomic screening holds great promise for presymptomatic identification of hidden disease, and prevention of dramatic events, including sudden cardiac death associated with arrhythmogenic cardiomyopathy (ACM). Herein, we present findings from clinical follow-up of carriers of ACM-associated pathogenic/likely pathogenic desmosome variants ascertained through genomic screening. METHODS: Of 64 548 eligible participants in Geisinger MyCode Genomic Screening and Counseling program (2015-present), 92 individuals (0.14%) identified with pathogenic/likely pathogenic desmosome variants by clinical laboratory testing were referred for evaluation. We reviewed preresult medical history, patient-reported family history, and diagnostic testing results to assess both arrhythmogenic right ventricular cardiomyopathy and left-dominant ACM. RESULTS: One carrier had a prior diagnosis of dilated cardiomyopathy with arrhythmia; no other related diagnoses or diagnostic family history criteria were reported. Fifty-nine carriers (64%) had diagnostic testing in follow-up. Excluding the variant, 21/59 carriers satisfied at least one arrhythmogenic right ventricular cardiomyopathy task force criterion, 11 (52%) of whom harbored DSP variants, but only 5 exhibited multiple criteria. Six (10%) carriers demonstrated evidence of left-dominant ACM, including high rates of atypical late gadolinium enhancement by magnetic resonance imaging and nonsustained ventricular tachycardia. Two individuals received new cardiomyopathy diagnoses and received defibrillators for primary prevention. CONCLUSIONS: Genomic screening for pathogenic/likely pathogenic variants in desmosome genes can uncover both left- and right-dominant ACM. Findings of overt cardiomyopathy were limited but were most common in DSP-variant carriers and notably absent in PKP2-variant carriers. Consideration of the pathogenic/likely pathogenic variant as a major criterion for diagnosis is inappropriate in the setting of genomic screening.
Assuntos
Displasia Arritmogênica Ventricular Direita/diagnóstico , Desmossomos/genética , Variação Genética , Adulto , Idoso , Displasia Arritmogênica Ventricular Direita/genética , Displasia Arritmogênica Ventricular Direita/patologia , Desmocolinas/genética , Desmogleína 2/genética , Ecocardiografia , Feminino , Ventrículos do Coração/diagnóstico por imagem , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Placofilinas/genéticaRESUMO
Plectin, a highly versatile cytolinker protein, provides tissues with mechanical stability through the integration of intermediate filaments (IFs) with cell junctions. Here, we hypothesize that plectin-controlled cytoarchitecture is a critical determinant of the intestinal barrier function and homeostasis. Mice lacking plectin in an intestinal epithelial cell (IEC; PleΔIEC) spontaneously developed colitis characterized by extensive detachment of IECs from the basement membrane (BM), increased intestinal permeability, and inflammatory lesions. Moreover, plectin expression was reduced in the colons of ulcerative colitis (UC) patients and negatively correlated with the severity of colitis. Mechanistically, plectin deficiency in IECs led to aberrant keratin filament (KF) network organization and the formation of dysfunctional hemidesmosomes (HDs) and intercellular junctions. In addition, the hemidesmosomal α6ß4 integrin (Itg) receptor showed attenuated association with KFs, and protein profiling revealed prominent downregulation of junctional constituents. Consistent with the effects of plectin loss in the intestinal epithelium, plectin-deficient IECs exhibited remarkably reduced mechanical stability and limited adhesion capacity in vitro. Feeding mice with a low-residue liquid diet that reduced mechanical stress and antibiotic treatment successfully mitigated epithelial damage in the PleΔIEC colon.
Assuntos
Colite Ulcerativa/metabolismo , Colite/metabolismo , Colo/patologia , Mucosa Intestinal/metabolismo , Plectina/metabolismo , Adulto , Idoso , Animais , Colite/prevenção & controle , Colite Ulcerativa/prevenção & controle , Desmossomos/genética , Desmossomos/metabolismo , Modelos Animais de Doenças , Feminino , Humanos , Mucosa Intestinal/patologia , Queratinas/metabolismo , Masculino , Camundongos , Camundongos Knockout , Pessoa de Meia-Idade , Plectina/genética , Adulto JovemRESUMO
The excretory system ultrastructure and immunocytochemistry have been investigated in the plerocercoid Pyramicocephalus phocarum. It has been shown that P. phocarum has independent terminal cells, cyrtocytes. The entire canal system is a single undivided syncytium, which includes nephridial funnels of the terminal tubules, and peripheral and central canals. The nephridial funnel and cyrtocyte form a filtration complex of the protonephridial type. In the caudal region, several peripheral canals open into a deep fold of the tegument, the urinary bladder. The excretory pores are separated from the tegument by annular septate desmosomes. There are no cell junctions inside the excretory system. The presence of the F-actin ring and the expression of non-synaptic serotonin in the collar area have been detected in cyrtocytes by immunocytochemistry methods.
Assuntos
Cestoides/ultraestrutura , Desmossomos/genética , Junções Intercelulares/genética , Bexiga Urinária/metabolismo , Actinas/genética , Animais , Cestoides/metabolismo , Cestoides/fisiologia , Regulação da Expressão Gênica/genética , Células Gigantes/metabolismo , Células Gigantes/fisiologia , Junções Intercelulares/metabolismo , Serotonina/genética , Bexiga Urinária/ultraestruturaRESUMO
The desmosome is a type of intercellular junction found in epithelial cells, cardiomyocytes and other specialized cell types. Composed of a network of transmembranous cadherins and intracellular armadillo, plakin and other proteins, desmosomes contribute to cell-cell adhesion, signalling, development and differentiation. Mutations in genes encoding desmosomal proteins result in a spectrum of erosive skin and mucosal phenotypes that also may affect hair or heart. This review summarizes the molecular pathology and phenotypes associated with desmosomal dysfunction with a focus on inherited disorders that involve the skin/hair, as well as associated extracutaneous pathologies. We reviewed the relevant literature to collate studies of pathogenic human mutations in desmosomes that have been reported over the last 25 years. Mutations in 12 different desmosome genes have been documented, with mutations in nine genes affecting the skin/mucous membranes (DSG1, DSG3, DSC2, DSC3, JUP, PKP1, DSP, CDSN, PERP) and eight resulting in hair abnormalities (DSG4, DSC2, DSC3, JUP, PKP1, DSP, CDSN, PERP). Mutations in three genes can result in cardiocutaneous syndromes (DSC2, JUP, DSP), although mutations have been described in five genes in inherited heart disorders that may lack any dermatological manifestations (DSG2, DSC2, JUP, PKP2, DSP). Understanding the diverse nature of these clinical phenotypes, as well as the desmosome gene mutation(s), has clinical value in managing and counselling patients, as well as demonstrating the biological role and activity of specific components of desmosomes in skin and other tissues.
Assuntos
Desmossomos , Pele/patologia , Caderinas , Desmogleínas/genética , Desmossomos/genética , Humanos , Peptídeos e Proteínas de Sinalização Intercelular , Mutação , FenótipoRESUMO
Arrhythmogenic cardiomyopathy (ACM) is a familial disease, with approximately 60% of patients displaying a pathogenic variant. The majority of genes linked to ACM code for components of the desmosome: plakophilin-2 (PKP2), desmoglein-2 (DSG2) and desmocollin-2 (DSC2), plakoglobin (JUP) and desmoplakin (DSP). Genetic variants involving the desmosomes are known to cause dysfunction of cell-to-cell adhesions and intercellular gap junctions. In turn, this may result in failure to mechanically hold together the cardiomyocytes, fibrofatty myocardial replacement, cardiac conduction delay and ventricular arrhythmias. It is becoming clearer that pathogenic variants in desmosomal genes such as PKP2 are not only responsible for a mechanical dysfunction of the intercalated disc (ID), but are also the cause of various pro-arrhythmic mechanisms. In this review, we discuss in detail the different molecular interactions associated with desmosomal pathogenic variants, and their contribution to various ACM phenotypes.
Assuntos
Displasia Arritmogênica Ventricular Direita , Desmossomos , Arritmias Cardíacas/diagnóstico , Arritmias Cardíacas/genética , Displasia Arritmogênica Ventricular Direita/diagnóstico , Displasia Arritmogênica Ventricular Direita/genética , Desmossomos/genética , Humanos , Miocárdio , Placofilinas/genéticaRESUMO
BACKGROUND: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy, which is associated with life-threatening ventricular arrhythmias. Approximately 60% of patients carry a putative disease-causing genetic variant, but interpretation of genetic test results can be challenging. The aims of this study were to systematically reclassify genetic variants in patients with ARVC and to assess the impact on ARVC diagnosis. METHODS: This study included patients from the Multicenter Zurich ARVC Registry who hosted a genetic variant deemed to be associated with the disease. Reclassification of pathogenicity was performed according to the modified 2015 American College of Medical Genetics criteria. ARVC diagnosis (categories: definite, borderline, possible) based on the 2010 Task Force Criteria was reclassified after genetic readjudication. RESULTS: In 79 patients bearing 80 unique genetic variants, n=47 (58.8%) genetic variants were reclassified, and reclassification was judged to be clinically relevant in n=33 (41.3%). Variants in plakophilin-2 (PKP2) were shown to reclassify less frequently as compared with other genes (PKP2, n=1, 8.3%; desmosomal non-PKP2, n=20, 66.7%; nondesmosomal, n=26, 68.4%; P=0.001for overall comparison; PKP2 versus desmosomal non-PKP2, P=0.001; PKP2 versus nondesmosomal, P<0.001). Genetic reclassification impacted ARVC diagnosis. Eight patients (10.1%) were downgraded from definite to borderline/possible disease at the time of initial genetic testing as well as last follow-up, respectively. Separate genetic reclassification in family members led to downgrading of n=5 (38.5%) variants. CONCLUSIONS: Given that approximately half of genetic variants were reclassified, with 10.1% of patients losing their definite disease status, accurate determination of variant pathogenicity is of utmost importance in the diagnosis of ARVC.