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[Display omitted] Healable electronic skins, an essential component for future soft robotics, implantable bioelectronics, and smart wearable systems, necessitate self-healable and pliable materials that exhibit functionality at intricate interfaces. Although a plethora of self-healable materials have been developed, the fabrication of highly conformal biocompatible functional materials on complex biological surfaces remains a formidable challenge. Inspired by regenerative properties of skin, we present the self-assembled transfer-printable liquid metal epidermis (SALME), which possesses autonomous self-healing capabilities at the oil–water interface. SALME comprises a layer of surfactant-grafted liquid metal nanodroplets that spontaneously assemble at the oil–water interface within a few seconds. This unique self-assembly property facilitates rapid restoration (<10 s) of SALME following mechanical damage. In addition to its self-healing ability, SALME exhibits excellent shear resistance and can be seamlessly transferred to arbitrary hydrophilic/hydrophobic curved surfaces. The transferred SALME effectively preserves submicron-scale surface textures on biological substrates, thus displaying tremendous potential for future epidermal bioelectronics. [ABSTRACT FROM AUTHOR]

General cellular aspects of skin development in vertebrates are presented with emphasis on the epidermis of sauropsids. Anamniote skin develops into a multilayered mucogenic and soft keratinized epidermis made of Intermediate Filament Keratins (IFKs) that is reinforced in most fish and few anurans by dermal bony and fibrous scales. In amniotes, the developing epidermis in contact with the amniotic fluid initially transits through a mucogenic phase recalling that of their anamniotes progenitors. A new gene cluster termed EDC (Epidermal Differentiation Complex) evolved in amniotes contributing to the origin of the stratum corneum. The EDC contains numerous genes coding for over 100 types of corneous proteins (CPs). In sauropsids 2–8 layers of embryonic epidermis accumulate soft keratins (IFKs) but do not form a compact corneous layer. The embryonic epidermis of reptiles and birds produces small amount of other, poorly known proteins in addition to IFKs and mucins. In the following development, a resistant corneous layer is formed underneath the embryonic epidermis that is shed before hatching. The definitive corneous epidermis of sauropsids is mainly composed of CBPs (Corneous beta proteins, formerly indicated as beta-keratins) derived from the EDC. CBPs belong to a gene sub-family of CPs unique for sauropsids, contain an inner amino acid region formed by beta-sheets, are rich in cysteine and glycine, and make most of the protein composition of scales, claws, beaks and feathers. In mammalian epidermis CPs missing the beta-sheet region are instead produced, and include loricrin, involucrin, filaggrin and various cornulins. Small amount of CPs accumulate in the 2–3 layers of mammalian embryonic epidermis and their appendages, that is replaced with the definitive corneous layers before birth. Differently from sauropsids, mammals utilize KAPs (keratin associated proteins) rich in cysteine and glycine for making the hard corneous material of hairs, claws, hooves, horns, and occasionally also scales. [Display omitted] • Amniote skin develops through an amphibious and then a terrestrial phase. • The mucogenic epidermis of fish and amphibians becomes corneous in amniotes. • In sauropsids the initially formed stratum corneum mainly produces Corneous Beta Proteins. • Genes for these proteins are localized in a locus known as Epidermal Differentiation Complex. • The accumulation of CBPs give rise to scales and other skin appendages including feathers in birds. [ABSTRACT FROM AUTHOR]

Axolotls have been considered to be able to regenerate their skin completely. Our recent study updated this theory with the finding that the lattice structure of dermal collagen fibers was not fully regenerated after skin injury. We also discovered that nerves induce the regeneration of collagen fibers. The mechanism of collagen fiber regeneration remains unknown, however. In this study, we focused on the structure of collagen fibers with collagen braiding cells, and cell origin in axolotl skin regeneration. In the wounded dermis, cells involved in skin repair/regeneration were derived from both the surrounding dermis and the subcutaneous tissue. Regardless of cell origin, cells acquired the proper cell morphology to braid collagen fiber with nerve presence. We also found that FGF signaling could substitute for the nerve roles in the conversion of subcutaneous fibroblasts to lattice-shaped dermal fibroblasts. Our findings contribute to the elucidation of the fundamental mechanisms of true skin regeneration and provide useful insights for pioneering new skin treatments. [Display omitted] • Collagen-producing cells in the axolotl dermis have lattice-patterned filopodia. • Dermal cells do not restore lattice morphology after skin injury. • Subcutaneous cells contribute to dermal reformation regardless of nerve presence. • Nerve factor FGFs induce the lattice formation of subcutaneous fibroblasts. [ABSTRACT FROM AUTHOR]

Stratified epithelia are made up of several layers of cells, which act as a protective barrier for the organ they cover. To ensure their shielding effect, epithelia are naturally able to cope with constant environmental insults. This ability is enabled by their morphology and architecture, as well as the continuous turnover of stem and progenitor cells that constitute their building blocks. Stem cell fate decisions and dynamics are fundamental key biological processes that allow epithelia to exert their functions. By focusing on the skin epidermis, this review discusses how tissue architecture is generated during development, maintained through adult life, and re-established during regeneration. [ABSTRACT FROM AUTHOR]

The lympho-epithelial Kazal-type inhibitors (LEKTI) are key to control skin turnover, and their absence causes Netherton syndrome. For clinical sample testing of LEKTI-based therapies, a robust analytical method to measure LEKTI-like activity in skin is required. This work reports on the development of a back-titration method to determine incremental LEKTI-like activity in skin samples. The method meets the analytical requirements for study sample testing, and reliable quantification can be achieved with negligible skin matrix interference. This assay does not provide analyte identity, but it can be used to measure treatment-driven increments of LEKTI-like activity within the skin epidermis. [Display omitted] • Lympho-epithelial Kazal-type inhibitors (LEKTI) regulate serine protease activity in skin, and their ablation causes Netherton Syndrome. • Enzyme-inhibitor titration assays are used to measure relative LEKTI potency, but they are not suitably characterized for clinical sample analysis. • This back-titration method has a fast workflow and yields quantitative, matrix interference-free data. • The presented method meets the major analytical requirements of accuracy and precision for clinical sample analyses. • This workflow contains important solutions to handle skin matrix interference and represents a potential advance in skin bioanalysis. [ABSTRACT FROM AUTHOR]

Plant growth occurs during both day and night and is associated with water loss via stomata. This chapter looks at the processes which are associated with water uptake and transpirational water loss during day and night, and how these processes relate to leaf growth and may be affected differently by the salt stress. Potential advantages and disadvantages of a night-time water loss and growth are discussed, particularly in the context of salinity and the uptake of excess Na+ and Cl- by the root system. The potential importance of aquaporins to enable a more selective uptake of water, compared with Na+ and Cl-, by the root under salinity is addressed. Both stomata and root aquaporins control plant water flow. Climate change and associated increases in temperature during the day and night period have the potential to impact differently on day- and night-time processes and on the adaptation of plants to salt stress. [ABSTRACT FROM AUTHOR]

Stomata are pores that form between pairs of guard cells and are commonly found in the leaf epidermis. The pores allow gaseous exchange between the inner air spaces of the leaf and the atmosphere, opening for CO2 entry to support photosynthesis and closing to reduce transpirational water loss. Guard cell membrane transport and its coordination play a central part in regulating the pore aperture. We know how guard cells respond to light, CO2 and drought with sufficient detail to model with quantitative accuracy their mechanics. By contrast, there is surprisingly little detail about the impact of salt stress on guard cells. Here we review the topic and introduce Na+ transport within the proven OnGuard3 modeling platform to question the mechanics of stomatal responses to salinity. The analysis indicates a critical role for ABA-mediated Ca2+ signaling as an early and overriding process leading to stomatal closure, a beneficial behavior for plants in the face of salt stress. [ABSTRACT FROM AUTHOR]

The plant hormone abscisic acid (ABA) triggers cellular tolerance responses to osmotic stress caused by high-salinity and water-deficient conditions. ABA controls the turgor pressure of guard cells in the plant epidermis through ionic fluxes via ion transporters anchored at the plasma membrane, leading to stomatal closure to limit transpiration and prevent the loss of water. However, stomatal apertures should be reversibly opened by a light signal to uptake carbon dioxide for photosynthesis, even under osmotic stress conditions. Plants utilize various strategies to regulate ABA-mediated stomatal closure in response to stressful conditions. Basically, plants regulate the accumulation of ABA, the signaling molecule induced in response to osmotic stress, during multiple metabolic processes (biosynthesis, catabolism, and conjugation) that occur in different subcellular organelles. In addition, the ABA signaling pathway in guard cells is modulated by ABA-dependent physical interactions among its core components, namely ABA molecules, receptors (e.g., pyrabactin resistance [PYR]/PYR1-like/regulatory components of ABA receptors), protein phosphatases (e.g., protein phosphatase type 2C), and kinases (e.g., sucrose non-fermenting-related protein kinase 2). Moreover, ABA induces the expression of numerous genes encoding proteins exerting either positive or negative effects on its accumulation, transportation, and signaling network. In parallel, the ABA signaling network can be desensitized by degradation of its core components via the ubiquitin-26S proteasome system or endocytic/vacuolar pathway in an ABA-dependent manner. This chapter details the mechanisms by which ABA constitutes a regulatory loop to finely tune its own homeostasis and signaling network, thereby modulating the stomatal operation. [ABSTRACT FROM AUTHOR]

Sustained inflammatory responses delay wound repair in diabetic skin. The stimulator of interferon genes (STING) plays a vital role in the innate immune responses. However, its function in diabetic skin wound repair, and the underlying mechanism remains unclear. Here, we reported that STING activation is a pathogenic marker that correlates with delayed wound repair in diabetic skin. Firstly, we found that STING expression is enhanced in the epidermis of STZ induced diabetes mouse model and db/db mouse model. Consistently, we also found that STING expression was upregulated in keratinocytes with the high-glucose (HG) treatment. Moreover, silencing of STING accelerated wound healing in vitro. In vivo, inhibition of STING by c176 inhibited inflammatory response in the epidermis and accelerated wound healing in diabetic skin. In addition, we found that autophagy dysfunction is correlated with the expression of STING in epidermis of diabetic mice. Induction of autophagy by rapamycin significantly reduced STING expression in keratinocytes. Collectively, these results indicated that defects of autophagy might lead to the activation of STING and finally delay the diabetic wound healing. • STING expression is upregulated in wound area epidermis of diabetic skin. • STING silencing accelerated wound closure in vitro. • STING inhibition accelerated wound healing in diabetic skin. • Induction of Autophagy decreased STING expression in HG treated HaCaT cells. [ABSTRACT FROM AUTHOR]

Skin epidermis secretes apical extracellular matrix (aECM) as a protective barrier from the external environment. The aECM is highly dynamic and constantly undergoes remodeling during animal development. How aECM dynamics is temporally regulated during development, and whether and how its mis-regulation may impact epidermal cell morphology or function remains to be fully elucidated. Here, we report that the conserved Zn-finger transcription factor BLMP-1/Blimp1, which regulates epidermal development in C. elegans , controls apical cell shape of the epidermis by downregulation of aECM remodeling. Loss of blmp-1 causes upregulation of genes essential for molting, including bus-8 and mlt-8 , in adult, leading to an abnormal shape in the apical region of adult epidermal cells. The apical epidermal morphological defect is suppressed by reduction of bus-8 or mlt-8. BUS-8 is a key mannosyltransferase, which functions in glycosylation of N-linked glycoproteins; MLT-8 has a ganglioside GM2 lipid-binding domain and is implicated in signaling during molting, a process where the old cuticle is shed and synthesized anew. Overexpression of bus-8 or mlt-8 induces an apical epidermal cell defect as observed in blmp-1 mutants. MLT-8::GFP fusion protein is localized to lysosomes and secreted to aECM. BUS-8 is important for MLT-8 stability and lysosomal targeting, which may be regulated by BUS-8-mediated glycosylation of MLT-8 and function as a molting signaling cue in aECM remodeling. We propose that BLMP-1 represses MLT-8 expression and glycosylation in the epidermis to prevent inappropriate aECM remodeling, which is essential for maintenance of apical epidermal cell morphology during larva-to-adult transition. [Display omitted] • Loss of blmp-1 causes abnormality in apical epidermal morphology in C. elegans adult. • The Blmp-1 epidermal defect is suppressed by loss of bus-8 or mlt-8. • bus-8 is important for lysosomal localization and protein stability of MLT-8. • blmp-1 represses transcription of bus-8 and mlt-8 to control epidermal morphology. [ABSTRACT FROM AUTHOR]

Scleroderma, characterized by extensive fibrosis and vascular alterations, involves excessive fibroblast activation, uncontrolled inflammation, and abnormal collagen deposition. Previous studies showed that administrations of either 1,25(OH) 2 D 3 or vitamin D analog effectively decreased or reversed skin fibrosis by regulating the extracellular matrix homeostasis. The actions of 1,25(OH) 2 D 3 are mediated by the vitamin D receptor (VDR), a transcription regulator crucial for skin homeostasis. Although evidence suggests that keratinocyte-fibroblast interaction influences the development of scleroderma, the role of keratinocytes in scleroderma remains unknown. Here, we demonstrated that the ablation of VDR in keratinocytes greatly exacerbated dermal fibrosis in HOCl-induced scleroderma in mice. The deficiency of VDR in the epidermis marked increased dermal thickness, inflammatory cell infiltration, and severe collagen deposition in comparison to the control group in HOCl-treated skin. Moreover, significant elevations in expression levels of mRNA for collagen overproduction (Col1A1, Col1A2, Col3A1, α-SMA, MMP9, TGF-β1) and proinflammatory cytokines (IL-1β, IL-6, CXCL1, CXCL2) were observed in VDR conditional KO versus control mice following HOCl treatment. Collectively, these results suggest that VDR in keratinocytes plays a pivotal role in scleroderma progression, and the interplay between keratinocytes and fibroblasts deserves more attention regarding the exploration of the pathogenesis and treatment for scleroderma. • Epidermal VDR deficiency aggravates HOCl induced dermal fibrosis. • Epidermal VDR depletion exacerbates HOCl induced skin inflammation. • Crosstalk of epidermis and dermis is essential for progression of cutaneous fibrosis. [ABSTRACT FROM AUTHOR]

A physico-chemical characterization and drying kinetics study was performed for whole 'Rojo Brillante' persimmon subjected to hot-air drying at 35 ᵒC, 40 ᵒC and 45 ᵒC. Fruit was dried until a moisture content of 30 g water/100 g product, which is required to be considered dried persimmon. This moisture value was obtained after 12, 8 and 7 d when the drying process was applied at 35 ᵒC, 40 ᵒC and 45 ᵒC, respectively. All the drying treatments caused flesh structure changes, shrinkage and secondary epidermis formation. The final product's quality characteristics especially the texture, strongly depended on drying temperature. The fruit dried at 35 ᵒC exhibited a gelatinous internal texture and a thin secondary epidermis, similarly to that obtained during a natural drying process. The drying treatment at 40 ᵒC resulted in fruit having more rubbery flesh. However, the fruit dried at 45 ᵒC had a corky texture, with a very thick secondary epidermis that resulted in excessively tough fruit for commercialization purposes. The differences in flesh structure were revealed in the microstructural study by Cryo-FESEM. In all cases, soluble tannins content lowered to non-astringency values. Hot-air drying technology proved to be a good alternative to valorize discarded 'Rojo Brillante' persimmon. • Hot-air drying of whole 'Rojo Brillante' persimmon is studied for the first time. • The time required to reach 30 % moisture depended on the drying temperature. • Verma's model describes well the drying kinetics of whole persimmon. • The product's quality depended on the drying temperature, especially in texture terms. • Hot-air drying is proposed as a good strategy to revalorized discarded fruit of 'Rojo Brillante'. [ABSTRACT FROM AUTHOR]

The skin is exposed to various external stimuli. Keratinocytes, which are the main cell type in the epidermis, interact with peripheral sensory neurons and modulate neuronal activity. Recent studies have revealed that keratinocytes play crucial roles in nociception, and that ATP is one of the main mediators of signal transduction from keratinocytes to sensory neurons. However, no quantitative cellular level analyses of ATP-mediated information flow from keratinocytes to sensory dorsal root ganglion (DRG) neurons have been conducted. In this study, we performed simultaneous imaging of cell surface ATP and intracellular Ca2+ signals using both iATPSnFR, a genetically encoded ATP probe localized to the outside of the cell membrane, and the Ca2+ probe, Fura-red. Upon mechanical stimulation of the keratinocyte with a glass needle, an increase in Ca2+ and ATP release were observed around the stimulated area, and these phenomena were positively correlated. In cultured DRG neurons and keratinocytes neighboring the stimulated keratinocyte, increased intracellular Ca2+ concentration and levels of cell surface ATP on the side closer to the stimulated cell were detected. The ratio of Ca2+ response to input ATP signal was significantly larger in DRG neurons than in keratinocytes. We found that DRG neurons were more sensitive to ATP than keratinocytes, and therefore, only DRG neurons responded to ATP at 1 μM or lower concentrations when in co-culture with keratinocytes. Moreover, signals caused by moderate mechanical stimulation of keratinocytes were transmitted predominantly to DRG neurons. These findings would be important in the further determination of the detailed mechanism of nociception in the epidermis. • Mechanical stimuli evoke ATP release only at the stimulation site in keratinocytes. • ATP release and Ca2+ signaling are positively correlated in the stimulated area. • DRG neurons are more sensitive to ATP than keratinocytes. • Information about moderate stimuli is transmitted only to DRG neurons. [ABSTRACT FROM AUTHOR]

Adult epidermal development in Drosophila showcases a striking balance between en masse spreading of the developing adult precursor tissues and retraction of the degenerating larval epidermis. The adult precursor tissues, driven by both intrinsic plasticity and extrinsic mechanical cues, shape the segments of the adult epidermis and appendages. Here, we review the tissue architectural changes that occur during epidermal morphogenesis in the Drosophila pupa, with a particular emphasis on the underlying mechanical principles. We highlight recent developments in our understanding of adult epidermal morphogenesis. We further discuss the forces that drive these morphogenetic events and finally outline open questions and challenges. [ABSTRACT FROM AUTHOR]

Restoration of hair follicle (HF) regenerative capacity is the cornerstone in tissue engineering for the loss of regenerative capacity during in vitro expansion of skin-derived precursors (SKPs). Microenvironmental cues facilitated tissue or organ regeneration offers a potential strategy to overcome this difficulty. In our previous work, plantar dermis matrix homogenate (PD) has been proved to induce sweat glands regeneration both in vivo and in vitro. Here, we found PD also restore regenerative capacity of culture impaired HF spheroids (IHFS). Further, followed by our previous iTRAQ results, the CTHRC1 was identified as a potential regulator in PD facilitated restorative effects in HF regeneration. Knockout of Cthrc1 impaired HF regenerative capacity in spheroids, decreased the diameter of HF in 28 postnatal days mice and shortened invagination of HF bud in 18 days of gestation mice. In IHFS and Cthrc1−/− spheroids, PD partially restored HF regenerative capacity while Cthrc1−/− PD (PDKO) has less or no effect. Taken together, PD is an effective microenvironmental cues for HF regenerative capacity restoration and CTHRC1 played an important role in HF regeneration. • PD restores impaired hair follicle regenerative capacity. • CTHRC1 is an effector protein of PD. • CTHRC1 plays an important role in the restoration of hair follicle regenerative capacity. [ABSTRACT FROM AUTHOR]

Teleost fish fins, like all vertebrate limbs, comprise a series of bones laid out in characteristic pattern. Each fin's distal bony rays typically branch to elaborate skeletal networks providing form and function. Zebrafish caudal fin regeneration studies suggest basal epidermal-expressed Sonic hedgehog (Shh) promotes ray branching by partitioning pools of adjacent pre-osteoblasts. This Shh role is distinct from its well-studied Zone of Polarizing Activity role establishing paired limb positional information. Therefore, we investigated if and how Shh signaling similarly functions during developmental ray branching of both paired and unpaired fins while resolving cellular dynamics of branching by live imaging. We found shha is expressed uniquely by basal epidermal cells overlying pre-osteoblast pools at the distal aspect of outgrowing juvenile fins. Lateral splitting of each shha -expressing epidermal domain followed by the pre-osteoblast pools precedes overt ray branching. We use ptch2:Kaede fish and Kaede photoconversion to identify short stretches of shha +basal epidermis and juxtaposed pre-osteoblasts as the Shh/Smoothened (Smo) active zone. Basal epidermal distal collective movements continuously replenish each shha +domain with individual cells transiently expressing and responding to Shh. In contrast, pre-osteoblasts maintain Shh/Smo activity until differentiating. The Smo inhibitor BMS-833923 prevents branching in all fins, paired and unpaired, with surprisingly minimal effects on caudal fin initial skeletal patterning, ray outgrowth or bone differentiation. Staggered BMS-833923 addition indicates Shh/Smo signaling acts throughout the branching process. We use live cell tracking to find Shh/Smo restrains the distal movement of basal epidermal cells by apparent 'tethering' to pre-osteoblasts. We propose short-range Shh/Smo signaling promotes these heterotypic associations to couple instructive basal epidermal collective movements to pre-osteoblast repositioning as a unique mode of branching morphogenesis. [Display omitted] • Shh/Smo signaling is restricted to distal shha + basal epidermal cells and adjacent pre-osteoblasts in developing zebrafish fins. • Sustained Shh/Smo signaling promotes ray branching morphogenesis in all unpaired and paired fins. • Shh/Smo largely is dedicated to ray branching throughout caudal fin development. • Collectively distal-moving, shha + basal epidermal cells slow while transiently associated with underlying pre-osteoblasts. • Shh/Smo may tether pre-osteoblasts to laterally-splitting shha-expressing basal epidermis, thereby partitioning ray-forming cell pools. [ABSTRACT FROM AUTHOR]

We have previously shown that the Kunitz-type serine protease inhibitor Spint1a, also named Hai1a, is required in the zebrafish embryonic epidermis to restrict the activity of the type II transmembrane serine protease (TTSP) Matriptase1a/St14a, thereby ensuring epidermal homeostasis. A closely related Kunitz-type inhibitor is Spint2/Hai2, which in mammals plays multiple developmental roles that are either redundant or non-redundant with those of Spint1. However, the molecular bases for these non-redundancies are not fully understood. Here, we study spint2 during zebrafish development. It is co-expressed with spint1a in multiple embryonic epithelia, including the outer/peridermal layer of the epidermis. However, unlike spint1a , spint2 expression is absent from the basal epidermal layer but present in hatching gland cells. Hatching gland cells derive from the mesendodermal prechordal plate, from where they undergo a thus far undescribed transit into, and coordinated sheet migration within, the interspace between the outer and basal layer of the epidermis to reach their final destination on the yolk sac. Hatching gland cells usually survive their degranulation that drives embryo hatching but die several days later. In spint2 mutants, cohesion among hatching gland cells and their collective intra-epidermal migration are disturbed, leading to a discontinuous organization of the gland. In addition, cells undergo precocious cell death before degranulation, so that embryos fail to hatch. Chimera analyses show that Spint2 is required in hatching gland cells, but not in the overlying periderm, their potential migration and adhesion substrate. Spint2 acts independently of all tested Matriptases, Prostasins and other described Spint1 and Spint2 mediators. However, it displays a tight genetic interaction with and acts at least partly via the cell-cell adhesion protein E-cadherin, promoting both hatching gland cell cohesiveness and survival, in line with formerly reported effects of E-cadherin during morphogenesis and cell death suppression. In contrast, no such genetic interaction was observed between Spint2 and the cell-cell adhesion molecule EpCAM, which instead interacts with Spint1a. Our data shed new light onto the mechanisms of hatching gland morphogenesis and hatching gland cell survival. In addition, they reveal developmental roles of Spint2 that are strikingly different from those of Spint1, most likely due to differences in the expression patterns and relevant target proteins. [Display omitted] • Hatching gland formation involves cell intercalations and collective cell migrations. • Hatching gland cells (HGCs) become organized as an epithelial-like monolayer. • HGC monolayer undergoes sheet migration between outer and basal layer of epidermis. • Protease inhibitor Spint2 is needed for HGC cohesion, sheet migration and survival. • Spint2 acts at least partially via the cell-cell adhesion protein E-cadherin. [ABSTRACT FROM AUTHOR]

Hedgehog (Hh) signaling is essential for the regulation of embryonic growth and development, the maintenance of stem cell autostasis, and tissue formation, whether in vertebrates or invertebrates. However, exploration into the Hh pathway antagonists in Drosophila or other pests of agricultural importance has been scant. In order to gain a better understanding of the potential utility of the antagonists in insect investigations, a conventional Hh antagonist, sonidegib, was used to evaluate the effects on the development of Drosophila larvae. The results showed that early instar larvae exposed to sonidegib exhibited new epidermal abnormalities and decreased motility after molting. Transcriptome analysis revealed that Sonidegib had a profound effect on chitin-based cuticle development throughout all stages of larvae. Physiological experiments revealed that sonidegib suppressed the epidermis formation and decreased the chitin content. The results of this study shed new light on the potential use of Hh antagonists in agricultural pest management. [Display omitted] • Sonidegib impaired molting and mobility in Drosophila early instar larvae. • Transcriptome sequencing showed enriched chitin-based cuticle development in larvae. • Sonidegib suppressed D. melanogaster larval epidermis formation. [ABSTRACT FROM AUTHOR]

Melanoma spheroid-loaded 3D skin models allow for the study of crucial tumor characteristics and factors at a superior level because the neoplastic cells are integrated into essential human skin components, permitting tumor–skin model communication. Herein, we designed a melanoma-containing artificial dermis by inserting multicellular tumor spheroids from the metastatic phase of WM 1617 melanoma cells into an artificial dermis. We cultured multicellular melanoma spheroids by hanging drop method (250 cells per drop) with a size of 420 μm in diameter after incubation for 14 days. These spheroids were integrated into the dermal equivalents that had been previously preparedwith a type-I collagen matrix and healthy fibroblasts. The melanoma spheroid cells invaded and proliferated in the artificial dermis. Spheroids treated with a 1.0 μmol/L aluminum chloride phthalocyanine nanoemulsion in the absence of light showed high cell viability. In contrast, under irradiation with visible red light (660 nm) at 25 J/cm2, melanoma cells were killed and the healthy tissue was preserved, indicating that photodynamic therapy is effective in such a model. Therefore, the 3D skin melanoma model has potential to promote research in full-thickness skin model targeting optimized preclinical assays. [ABSTRACT FROM AUTHOR]

During fetal development, the barrier function of the fetal skin is developed under specific conditions for epidermis formation. In keratinocyte differentiation, the well-orchestrated production and modification of various structural proteins are induced. We assessed the epidermal barrier function in different fetal stages by evaluating the enzymatic activity of cross-linking proteins, transglutaminases, and the permeation of fluorescence dye in the stained epidermal sections. During days 15.5–17.5 in gestation, the enzymatic activities in the epidermis appeared to increase significantly; meanwhile, dye permeation was substantially decreased, suggesting the formation of a protective barrier. For the fetal epidermis formation in the earlier stage, unclarified stimulating factors in the amniotic fluid (AF) are possible to promote barrier function by stimulating keratinocyte differentiation. Thus, we performed proteomic spectrometric (MS) analysis on the components in the AF at different fetal stages. Also, we investigated the promotive ability of the components using a cultured keratinocyte differentiation system. According to the MS analysis, the AF components appeared to exhibit stage-specific variations, where possible unique functions have been identified. We also found that adding the AF from each stage to the medium for cultured keratinocytes specifically enhanced the levels of the differentiation markers. These results provide information on the possible role of AF that contains regulatory factors on keratinocyte differentiation. [Display omitted] • The barrier function of the fetal mouse skin evaluated at developmental stages. • Protein composition in the amniotic fluid analyzed by mass spectrometry. • Keratinocyte differentiation factors detected in the amniotic fluid. • Two transglutaminases in the fetal skin with distinct patterns of activation. • The expressions of transglutaminases and substrates regulated by amniotic fluid. [ABSTRACT FROM AUTHOR]

• Current in silico multicellular models of the epithelia potentially cause erroneous loss of stem cells from the stem cell niche. • Niche populations can be maintained at a desired density through a new mechanism which regulates the orientation of division. • Regulation of the orientation of the division is acting as a phenomenological model for the regulation of the mitotic spindle during division. The maintenance of the proliferative cell niche is critical to epithelial tissue morphology and function. In this paper we investigate how current modelling methods can result in the erroneous loss of proliferative cells from the proliferative cell niche. Using an established model of the inter-follicular epidermis we find there is a limit to the proliferative cell densities that can be maintained in the basal layer (the niche) if we do not include additional mechanisms to stop the loss of proliferative cells from the niche. We suggest a new methodology that enables maintenance of a desired homeostatic population of proliferative cells in the niche: a rotational force is applied to the two daughter cells during the mitotic phase of division to enforce a particular division direction. We demonstrate that this new methodology achieves this goal. This methodology reflects the regulation of the orientation of cell division. [ABSTRACT FROM AUTHOR]

Systemic toxicity assessments for oral or parenteral drugs often utilize the concentration of drug in plasma to enable safety margin calculations for human risk assessment. For topical drugs, there is no standard method for measuring drug concentrations in the stratum basale of the viable epidermis. This is particularly important since the superficial part of the epidermis, the stratum corneum (SC), is nonviable and where most of a topically applied drug remains, never penetrating deeper into the skin. We investigated the relative concentrations of a prototype kinase inhibitor using punch biopsy, laser capture microdissection, and imaging mass spectrometry methods in the SC, stratum basale, and dermis of minipig skin following topical application as a cream formulation. The results highlight the value of laser capture microdissection and mass spectrometry imaging in quantifying the large difference in drug concentration across the skin and even within the epidermis, and supports use of these methods for threshold-based toxicity risk assessments in specific anatomic locations of the skin, like of the stratum basale. • Measurement of topical drug concentrations in viable epidermis. • Drug concentration measurement in skin for risk assessment. • Skin concentrations by laser capture microdissection. • Skin concentrations and distribution by mass spectrometry. [ABSTRACT FROM AUTHOR]