Expression of Desmoglein 1 Compensates for Genetic Loss of Desmoglein 3 in Keratinocyte Adhesion

The desmoglein compensation hypothesis, namely that one desmoglein can compensate for loss of function of another, has been proposed to explain the tissue specificity of the autoantibody-induced loss of cell adhesion in pemphigus. To validate this hypothesis genetically, we used desmoglein-3 knockout mice (DSG3–/–) that lose their telogen hair prematurely due to loss of adhesion between keratinocytes of the telogen hair club and the outer root sheath, where the only desmoglein expressed in normal mice is desmoglein-3. To determine if desmoglein-1 could substitute for the function of desmoglein-3 in telogen hair, we produced transgenic mice that express desmoglein-1 driven off the keratin 14 promoter, and then bred the transgene (TG) into DSG3–/– mice. Immunoblotting showed transgene expression in skin, and immunofluorescence showed desmoglein-1 in the telogen club of DSG3–/–TG+ but not DSG3–/–TG– mice. DSG3–/–TG– mice lost telogen hair with each wave of telogen, whereas DSG3–/–TG+ mice had markedly delayed and decreased hair loss. DSG3–/– mice also show low weights due to blisters in the oral mucosa. Surprisingly, DSG3–/–TG+ mice showed similar low weights, because the transgene, although expressed in skin, was not well expressed in oral mucous membranes. These studies show that desmoglein-1 can compensate for loss of desmoglein-3-mediated adhesion, and provide genetic evidence confirming the desmoglein compensation hypothesis

Inflammatory Mediator TAK1 Regulates Hair Follicle Morphogenesis and Anagen Induction Shown by Using Keratinocyte-Specific TAK1-Deficient Mice

Transforming growth factor-β-activated kinase 1 (TAK1) is a member of the NF-κB pathway and regulates inflammatory responses. We previously showed that TAK1 also regulates keratinocyte growth, differentiation, and apoptosis. However, it is unknown whether TAK1 has any role in epithelial–mesenchymal interactions. To examine this possibility, we studied the role of TAK1 in mouse hair follicle development and cycling as an instructive model system. By comparing keratinocyte-specific TAK1-deficient mice (Map3k7fl/flK5-Cre) with control mice, we found that the number of hair germs (hair follicles precursors) in Map3k7fl/flK5-Cre mice was significantly reduced at E15.5, and that subsequent hair follicle morphogenesis was retarded. Next, we analyzed the role of TAK1 in the cyclic remodeling in follicles by analyzing hair cycle progression in mice with a tamoxifen-inducible keratinocyte-specific TAK1 deficiency (Map3k7fl/flK14-Cre-ERT2). After active hair growth (anagen) was induced by depilation, TAK1 was deleted by topical tamoxifen application. This resulted in significantly retarded anagen development in TAK1-deficient mice. Deletion of TAK1 in hair follicles that were already in anagen induced premature, apoptosis-driven hair follicle regression, along with hair follicle damage. These studies provide the first evidence that the inflammatory mediator TAK1 regulates hair follicle induction and morphogenesis, and is required for anagen induction and anagen maintenance

Downregulation of E-cadherin and Desmoglein 1 by autocrine hepatocyte growth factor during melanoma development

During melanoma development, transformed cells evade keratinocyte-mediated control by downregulating cell adhesion molecules. This study investigated the regulation of cell adhesion by hepatocyte growth factor (HGF) in melanoma. Melanocytes and two melanoma lines, WM164 and WM35, expressed normal level E-cadherin and Desmoglein 1, whereas most melanomas (18 out of 20) expressed no E-cadherin and significantly reduced Desmoglein 1. Overexpression of dominant negative E-cadherin and Desmoglein in melanocytes demonstrated that both molecules contribute to adhesion between melanocytes and keratinocytes. In contrast to melanocytes, most melanomas expressed HGF. All melanocytic cells expressed the HGF receptor c-Met, and autocrine HGF caused constitutive activation of c-Met, MAPK and PI3K. When autocrine activation was induced with HGF-expressing adenovirus, E-cadherin and Desmoglein 1 were decreased in melanocytes, WM164 and WM35. MAPK inhibitor PD98059 and PI3K inhibitor wortmannin partially blocked the downregulation, suggesting that both pathways are involved in this process. c-Met was coimmunoprecipitated with E-cadherin, Desmoglein 1 and Plakoglobin, suggesting that they form a complex (es) that acts to regulate intercellular adhesion. Together, the results indicate that autocrine HGF decouples melanomas from keratinocytes by downregulating E-cadherin and Desmoglein 1, therefore frees melanoma cells from the control by keratinocytes and allows dissemination of the tumor mass

Eccrine sweat contains IL-1α, IL-1β and IL-31 and activates epidermal keratinocytes as a danger signal.

Eccrine sweat is secreted onto the skin's surface and is not harmful to normal skin, but can exacerbate eczematous lesions in atopic dermatitis. Although eccrine sweat contains a number of minerals, proteins, and proteolytic enzymes, how it causes skin inflammation is not clear. We hypothesized that it stimulates keratinocytes directly, as a danger signal. Eccrine sweat was collected from the arms of healthy volunteers after exercise, and levels of proinflammatory cytokines in the sweat were quantified by ELISA. We detected the presence of IL-1α, IL-1β, and high levels of IL-31 in sweat samples. To investigate whether sweat activates keratinocytes, normal human keratinocytes were stimulated with concentrated sweat. Western blot analysis demonstrated the activation of NF-κB, ERK, and JNK signaling in sweat-stimulated keratinocytes. Real-time PCR using total RNA and ELISA analysis of supernatants showed the upregulation of IL-8 and IL-1β by sweat. Furthermore, pretreatment with IL-1R antagonist blocked sweat-stimulated cytokine production and signal activation, indicating that bioactive IL-1 is a major factor in the activation of keratinocytes by sweat. Moreover, IL-31 seems to be another sweat stimulator that activates keratinocytes to produce inflammatory cytokine, CCL2. Sweat is secreted onto the skin's surface and does not come into contact with keratinocytes in normal skin. However, in skin with a defective cutaneous barrier, such as atopic dermatitis-affected skin, sweat cytokines can directly act on epidermal keratinocytes, resulting in their activation. In conclusion, eccrine sweat contains proinflammatory cytokines, IL-1 and IL-31, and activates epidermal keratinocytes as a danger signal

Synthesis and evaluation of 11C-labeled coumarin analog as an imaging probe for detecting monocarboxylate transporters expression

Upregulated monocarboxylate transporters (MCTs) in tumors are considered diagnostic imaging targets.Herein, we synthesized the positron emission tomography probe candidates coumarin analogs 2 and 3,and showed 55 times higher affinity of 2 for MCTs than a representative MCT inhibitor. Whereas [11C]2 showed low tumor accumulation, probably due to adduct formation with plasma proteins, [11C]2showed high initial brain uptake, suggesting that the scaffold of 2 has properties that are preferable inimaging probes for the astrocyte–neuron lactate shuttle. Although further optimization of 2 is required,our findings can be used to inform the development of MCT-targeted imaging agents. 2017 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY licens