No abstract

A20 is a negative regulator of nuclear factor κ-light‑chain-enhancer of activated B cells (NF-κB) signaling, and has been implicated in the pathogenesis of psoriasis through genome-wide association study (GWAS). In the present study, we investigated the putative role of A20 in epidermal keratinocytes. Immunohistochemical analysis showed that A20 was expressed in all layers of the epidermis, with an increasing pattern in the upper layers. In our model of calcium-induced keratinocyte differentiation, A20 expression was increased in a time-dependent manner. To investigate whether A20 affected keratinocyte differentiation, we overexpressed A20 in cultured keratinocytes. As a result, we noted that A20 overexpression did not affect keratinocyte differentiation, suggesting that A20 is not a direct modulator of keratinocyte differentiation. Interestingly, we found that A20 levels were decreased in psoriatic lesional skin compared to non-lesional areas. To investigate whether A20 played a role in the innate immune response of keratinocytes, we overexpressed A20 and then examined poly(I:C)-induced cytokine expression. We noted that A20 significantly inhibited poly(I:C)-induced cytokine production, and this effect was related to the inhibition of NF-κB signaling. These results suggest that the downregulation of A20 increased the susceptibility of keratinocytes to external stimuli, thus contributing to the development of psoriasis.

No abstract

During a search for keratinocyte differentiation-related genes, we obtained a cDNA fragment from the 5'-untranslated region of a previously identified splicing variant of desmoglein 3 (Dg3). This transcript encodes a protein of 282 amino acids, which corresponds to the N-terminal truncated intracellular domain of Dg3 (ΔNDg3). Northern blot analysis detected a 4.6-kb transcript matching the predicted size of ΔNDg3 mRNA, and Western blot analysis with an antibody raised against the Dg3 C-terminus (H-145) detected a 31-kDa protein. Increased ΔNDg3 expression was observed in differentiating keratinocytes by RT-PCR and Western blot analysis, suggesting that ΔNDg3 is indeed a differentiation-related gene product. In immunohistochemical studies of normal and pathologic tissues, H-145 antibody detected the protein in the cytoplasm of suprabasal layer cells, whereas an antibody directed against the N-terminal region of Dg3 (AF1720) reacted with a membrane protein in the basal layer. In addition, ΔNDg3 transcript and protein were upregulated in psoriatic epidermis, and protein expression appeared to increase in epidermal tumors including Bowen's disease and squamous cell carcinoma. Moreover, overexpression of ΔNDg3 led to increased migration and weakening of cell adhesion. These results suggest that ΔNDg3 have a role in keratinocyte differentiation, and that may be related with tumorigenesis of epithelial origin.

We report a case of an isolated plexiform neurofibroma occurring in a patient with myasthenia gravis. A 48-year-old man presented with asymptomatic skin-colored nodules on the tip of his 4th finger. Microscopically, a plexiform neurofibroma was identified located in the dermis that appeared to originate from small superficial nerves. He had a 20-year history of treated myasthenia gravis; otherwise, his personal and family histories were unremarkable. Given that myasthenia gravis is a disorder of the peripheral nerves, plexiform neurofibromas could be associated with myasthenia gravis. However, the development of an isolated plexiform neurofibroma in a case of myasthenia gravis has not yet been reported. The occurrence of a neurofibromas in a patient with myasthenia gravis suggests a link in the pathogenesis of these two diseases. (Ann Dermatol (Seoul) 21(1) 53∼55, 2009)