Contribution of the different modules in the utrophin carboxy-terminal region to the formation and regulation of the DAP complex

AbstractThe carboxy-terminal region of utrophin, like the homologous proteins dystrophin, Drp2 and dystrobrevins, contains structural domains frequently involved in protein–protein interaction. These domains (WW, EF hands, ZZ and H1–H2) mediate recognition and binding to a multicomponent complex of proteins, also known as dystrophin-associated proteins (DAPs) for their association with dystrophin, the product of the gene, mutated in Duchenne muscular dystrophy. We have exploited phage display and in vitro binding assays to study the recognition specificity of the different domains of the utrophin carboxy-terminus. We found that none of the carboxy-terminal domains of utrophin, when isolated from its structural context, selects specific ligand peptides from a phage-displayed peptide library. By contrast, panning with an extended region containing the WW, EF hands, and ZZ domain defines the consensus binding motif, PPxY which is also found in β-dystroglycan, a component of the DAP complex that interacts with utrophin in several tissues. WW-mediated binding to PPxY peptides and to β-dystroglycan requires the presence of the EF hands and ZZ domain. When the ZZ domain is either deleted or engaged in binding to calmodulin, the utrophin β-dystroglycan complex cannot be formed. These findings suggest a potential regulatory mechanism by means of which the attachment of utrophin to the DAP complex can be modulated by the Ca2+-dependent binding of calmodulin. The remaining two motifs found in the carboxy-terminus (H1–H2) mediate the formation of utrophin–dystrobrevin hybrids but do not select ligands in a repertoire of random nonapeptides

Paraneoplastic Pemphigus Presenting as Mild Cutaneous Features of Pemphigus Foliaceus and Lichenoid Stomatitis with Antidesmoglein 1 Antibodies

Herein, we report a case of paraneoplastic pemphigus with mild skin features of pemphigus foliaceus and lichenoid stomatitis associated with B-cell lymphoma. A 49-year-old man presented with scattered blisters and erosions on the trunk along with mucosal blisters and erosions. Skin biopsy showed subcorneal acantholytic bulla and oral mucosal biopsy demonstrated lichenoid dermatitis. Direct immunofluorescence showed cell surface deposits of IgG and C3. Indirect immunofluorescence identified circulating IgG autoantibodies to the cell surfaces of normal human skin and also on the transitional epithelium of rat bladder. Enzyme-linked immunosorbent assay using recombinant baculoproteins showed positive antidesmoglein 1 autoantibodies (index 46) but negative antidesmoglein 3 autoantibodies (index 8). Immunoblot analysis using normal human epidermal extract detected BP230 and the 190 kDa periplakin, while immunoprecipitation using radiolabeled cultured keratinocyte immunoprecipitated BP230 and the 210 kDa envoplakin. We consider that the skin lesion was produced by humoral immunity whereas the oral lesion was produced by cellular immunity

Identification of a novel non-desmoglein autoantigen in Pemphigus Vulgaris

Pemphigus vulgaris (PV) is an autoimmune bullous disease of the skin and mucous membranes characterized by the presence of circulating and tissue-bound autoantibodies against keratinocyte cell surface antigens, specifically desmoglein (Dsg) 1 and 3. The pathogenic role of anti-Dsg antibodies is well-established, while the mechanism of blister formation is only partly defined. We have applied a previously developed method for the efficient immortalization of IgG+ memory B cells to identify novel target antigens in PV. A human monoclonal antibody reactive with a hitherto unreported non-Dsg antigen was isolated. Immunoprecipitation and immunoblotting studies with keratinocyte extracts indicated α-catenin as the putative antigen, then confirmed by immunoblotting on the recombinant protein. Four of ten PV sera reacted with recombinant α- catenin. Although the isolated human monoclonal antibody was per se unable to dissociate keratinocyte monolayers and also to synergize with a pathogenic antibody in vitro, further studies are warranted to assess its possible in vivo contribution in the multifactorial pathogenesis and heterogeneous manifestations of PV disease

Paraneoplastic epidermolysis bullosa acquisita associated with thyroid carcinoma

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Case report: bullous pemphigoid development underlies dystrophic epidermolysis bullosa disease worsening

Autoimmune response to cutaneous basement membrane components superimposed on a genetic skin fragility disease, hereditary epidermolysis bullosa (EB), has been described, but its effects on disease course remain unclear. We report a 69-year-old individual with congenital skin fragility and acral trauma-induced blistering that had suddenly worsened with the onset of severe itch and diffuse spontaneous inflammatory blisters. Next-generation sequencing identified compound heterozygous null and missense COL7A1 mutations, allowing the diagnosis of recessive dystrophic EB. However, the patient’s clinical history prompted us to investigate whether he might have developed a pathological autoimmune response against basement membrane components. Tissue-bound and circulating IgG antibodies to the major bullous pemphigoid (BP) antigen, BP180, were detected in the patient’s skin and serum, respectively, consistent with a diagnosis of BP. Corticosteroid therapy was initiated resulting in remission of BP manifestations. EB patients presenting rapid disease worsening should be investigated for the development of a concomitant autoimmune blistering disease

Environmental factors in autoimmune bullous diseases with focusing on seasonality: new insights

Autoimmune bullous diseases are a heterogeneous group of rare conditions clinically characterized by the presence of blisters and/or erosions on the skin and on the mucous membranes. Practically, they can be divided into two large groups: the pemphigoid group and the pemphigus group, depending on the depth of the autoimmune process on the skin. Family history of autoimmune disease can often be found, and demonstrating that genetic predisposition is crucial in the development of them. Moreover, numerous environmental risk factors, such as solar radiation, drugs and infections, are known. This study aimed to evaluate how seasonality can affect the trend of BP and PV, especially considering the number of hospitalizations recorded over the course of individual months. The total number of hospitalizations in the twelve months of the year was evaluated. Further, blood chemistry assay and, for some patients, enzyme-linked immunosorbent assay were executed in order to evaluate antibodies. Regarding the severity of the disease BPDAI (Bullous Pemphigoid Area Index) and PDAI (Pemphigus Disease Area Index), score systems were used. Results showed a complex interplay between environmental factors such as seasons and autoimmune conditions

Meeting Report of the Pathogenesis of Pemphigus and Pemphigoid Meeting in Munich, September 2016

Autoimmune blistering diseases are a heterogeneous group of about a dozen complex disorders that are characterized by intraepidermal (pemphigus) and subepidermal blistering (pemphigoid diseases and dermatitis herpetiformis). The Pathogenesis of Pemphigus and Pemphigoid Meeting, organized by the Departments of Dermatology in Lubeck and Marburg and the Institute of Anatomy and Cell Biology, Munich, was held in September 2016 in Munich. The meeting brought together basic scientists and clinicians from all continents dedicating their work to autoimmune blistering diseases. Considerable advances have been made in describing incidences and prevalences of these diseases and linking comorbidities with autoantibody reactivities and clinical variants, for example, dipeptidyl peptidase-IV inhibitor-associated noninflammatory bullous pemphigoid. Although new entities are still being described, diagnosis of most autoimmune blistering diseases can now be achieved using standardized and widely available serological test systems. Various experimental mouse models of pemphigus and pemphigoid disease are increasingly being used to understand mechanisms of central and peripheral tolerance and to evaluate more specific treatment approaches for these disorders, such as molecules that target autoreactive T and B cells and anti-inflammatory mediators, that is, dimethyl fumarate, phosphodiesterase 4, and leukotriene B4 inhibitors in pemphigoid disorders, and chimeric antigen receptor T cells in pemphigus. Very recent experimental data about the immunopathology and the determinants of autoantibody formation and keratinocyte susceptibility in pemphigus were discussed. With regard to cellular mechanisms leading to the loss of cell-cell adhesion, new ideas were shared in the field of signal transduction. Major steps were taken to put the various partly contradictory and controversial findings about the effects of pemphigus autoantibodies and other inflammatory mediators into perspective and broaden our view of the complex pathophysiology of this disease. Finally, two investigator-initiated multicenter trials highlighted doxycycline and dapsone as valuable medications in the treatment of bullous pemphigoid.Non peer reviewe