New techniques enable comparative analysis of microtubule orientation, wall texture, and growth rate in intact roots of Arabidopsis.

PubMed

Sugimoto, K; Williamson, R E; Wasteneys, G O

2000-12-01

This article explores root epidermal cell elongation and its dependence on two structural elements of cells, cortical microtubules and cellulose microfibrils. The recent identification of Arabidopsis morphology mutants with putative cell wall or cytoskeletal defects demands a procedure for examining and comparing wall architecture and microtubule organization patterns in this species. We developed methods to examine cellulose microfibrils by field emission scanning electron microscopy and microtubules by immunofluorescence in essentially intact roots. We were able to compare cellulose microfibril and microtubule alignment patterns at equivalent stages of cell expansion. Field emission scanning electron microscopy revealed that Arabidopsis root epidermal cells have typical dicot primary cell wall structure with prominent transverse cellulose microfibrils embedded in pectic substances. Our analysis showed that microtubules and microfibrils have similar orientation only during the initial phase of elongation growth. Microtubule patterns deviate from a predominantly transverse orientation while cells are still expanding, whereas cellulose microfibrils remain transverse until well after expansion finishes. We also observed microtubule-microfibril alignment discord before cells enter their elongation phase. This study and the new technology it presents provide a starting point for further investigations on the physical properties of cell walls and their mechanisms of assembly.

The Epidermal Cell Structure of the Secondary Pollen Presenter in Vangueria infausta (Rubiaceae: Vanguerieae) Suggests a Functional Association with Protruding Onci in Pollen Grains

PubMed Central

Tilney, Patricia M.; van Wyk, Abraham E.; van der Merwe, Chris F.

2014-01-01

Secondary pollen presentation is a well-known phenomenon in the Rubiaceae with particularly conspicuous pollen presenters occurring in the tribe Vanguerieae. These knob-like structures are formed by a modification of the upper portion of the style and stigma, together known as the stylar head complex. In the flower bud and shortly before anthesis, the anthers surrounding the stylar head complex dehisce and release pollen grains which adhere to the pollen presenter. The epidermal cells of the pollen presenter facing the anthers are radially elongated with a characteristic wall thickening encircling the anticlinal walls of each cell towards the distal end. These cells were studied in the pollen presenter of Vangueria infausta using electron and light microscopy in conjunction with histochemical tests and immunohistochemical methods. Other prominent thickenings of the cell wall were also observed on the distal and proximal walls. All these thickenings were found to be rich in pectin and possibly xyloglucan. The terms “thickenings of Igersheim” and “bands of Igersheim” are proposed to refer, respectively, to these wall structures in general and those encircling the anticlinal walls of each cell near the distal end. The epidermal cells have an intricate ultrastructure with an abundance of organelles, including smooth and rough endoplasmic reticulum, Golgi apparatus, mitochondria and secretory vesicles. This indicates that these cells are likely to have an active physiological role. The pollen grains possess prominent protruding onci and observations were made on their structure and development. Walls of the protruding onci are also rich in pectin. Pectins are hydrophilic and known to be involved in the dehydration and rehydration of pollen grains. We hypothesise that the thickenings of Igersheim, as well as the protruding onci of the pollen grains, are functionally associated and part of the adaptive syndrome of secondary pollen presentation, at least in the Vanguerieae. PMID:24804803

Regulation of auxin on secondary cell wall cellulose biosynthesis in developing cotton fibers

USDA-ARS?s Scientific Manuscript database

Cotton (Gossypium hirsutum L.) fibers are unicellular trichomes that differentiate from epidermal cells of developing cotton ovules. Mature fibers exhibit thickened secondary walls composed of nearly pure cellulose. Cotton fiber development is divided into four overlapping phases, 1) initiation sta...

Transcript Profiling Identifies Gene Cohorts Controlled by Each Signal Regulating Trans-Differentiation of Epidermal Cells of Vicia faba Cotyledons to a Transfer Cell Phenotype

PubMed Central

Zhang, Hui-Ming; Wheeler, Simon L.; Xia, Xue; Colyvas, Kim; Offler, Christina E.; Patrick, John W.

2017-01-01

Transfer cells (TCs) support high rates of membrane transport of nutrients conferred by a plasma membrane area amplified by lining a wall labyrinth comprised of an uniform wall layer (UWL) upon which intricate wall ingrowth (WI) papillae are deposited. A signal cascade of auxin, ethylene, extracellular hydrogen peroxide (H2O2) and cytosolic Ca2+ regulates wall labyrinth assembly. To identify gene cohorts regulated by each signal, a RNA- sequencing study was undertaken using Vicia faba cotyledons. When cotyledons are placed in culture, their adaxial epidermal cells spontaneously undergo trans-differentiation to epidermal TCs (ETCs). Expressed genes encoding proteins central to wall labyrinth formation (signaling, intracellular organization, cell wall) and TC function of nutrient transport were assembled. Transcriptional profiles identified 9,742 annotated ETC-specific differentially expressed genes (DEGs; Log2fold change > 1; FDR p ≤ 0.05) of which 1,371 belonged to signaling (50%), intracellular organization (27%), cell wall (15%) and nutrient transporters (9%) functional categories. Expression levels of 941 ETC-specific DEGs were found to be sensitive to the known signals regulating ETC trans-differentiation. Significantly, signals acting alone, or in various combinations, impacted similar numbers of ETC-specific DEGs across the four functional gene categories. Amongst the signals acting alone, H2O2 exerted most influence affecting expression levels of 56% of the ETC-specific DEGs followed by Ca2+ (21%), auxin (18%) and ethylene (5%). The dominance by H2O2 was evident across all functional categories, but became more attenuated once trans-differentiation transitioned into WI papillae formation. Amongst the eleven signal combinations, H2O2/Ca2+ elicited the greatest impact across all functional categories accounting for 20% of the ETC-specific DEG cohort. The relative influence of the other signals acting alone, or in various combinations, varied across the four functional categories and two phases of wall labyrinth construction. These transcriptome data provide a powerful information platform from which to examine signal transduction pathways and how these regulate expression of genes encoding proteins engaged in intracellular organization, cell wall construction and nutrient transport. PMID:29234338

Transcript Profiling Identifies Gene Cohorts Controlled by Each Signal Regulating Trans-Differentiation of Epidermal Cells of Vicia faba Cotyledons to a Transfer Cell Phenotype.

PubMed

Zhang, Hui-Ming; Wheeler, Simon L; Xia, Xue; Colyvas, Kim; Offler, Christina E; Patrick, John W

2017-01-01

Transfer cells (TCs) support high rates of membrane transport of nutrients conferred by a plasma membrane area amplified by lining a wall labyrinth comprised of an uniform wall layer (UWL) upon which intricate wall ingrowth (WI) papillae are deposited. A signal cascade of auxin, ethylene, extracellular hydrogen peroxide (H 2 O 2 ) and cytosolic Ca 2+ regulates wall labyrinth assembly. To identify gene cohorts regulated by each signal, a RNA- sequencing study was undertaken using Vicia faba cotyledons. When cotyledons are placed in culture, their adaxial epidermal cells spontaneously undergo trans -differentiation to epidermal TCs (ETCs). Expressed genes encoding proteins central to wall labyrinth formation (signaling, intracellular organization, cell wall) and TC function of nutrient transport were assembled. Transcriptional profiles identified 9,742 annotated ETC-specific differentially expressed genes (DEGs; Log 2 fold change > 1; FDR p ≤ 0.05) of which 1,371 belonged to signaling (50%), intracellular organization (27%), cell wall (15%) and nutrient transporters (9%) functional categories. Expression levels of 941 ETC-specific DEGs were found to be sensitive to the known signals regulating ETC trans -differentiation. Significantly, signals acting alone, or in various combinations, impacted similar numbers of ETC-specific DEGs across the four functional gene categories. Amongst the signals acting alone, H 2 O 2 exerted most influence affecting expression levels of 56% of the ETC-specific DEGs followed by Ca 2+ (21%), auxin (18%) and ethylene (5%). The dominance by H 2 O 2 was evident across all functional categories, but became more attenuated once trans -differentiation transitioned into WI papillae formation. Amongst the eleven signal combinations, H 2 O 2 /Ca 2+ elicited the greatest impact across all functional categories accounting for 20% of the ETC-specific DEG cohort. The relative influence of the other signals acting alone, or in various combinations, varied across the four functional categories and two phases of wall labyrinth construction. These transcriptome data provide a powerful information platform from which to examine signal transduction pathways and how these regulate expression of genes encoding proteins engaged in intracellular organization, cell wall construction and nutrient transport.

The barley (Hordeum vulgare) cellulose synthase-like D2 gene (HvCslD2) mediates penetration resistance to host-adapted and nonhost isolates of the powdery mildew fungus.

PubMed

Douchkov, Dimitar; Lueck, Stefanie; Hensel, Goetz; Kumlehn, Jochen; Rajaraman, Jeyaraman; Johrde, Annika; Doblin, Monika S; Beahan, Cherie T; Kopischke, Michaela; Fuchs, René; Lipka, Volker; Niks, Rients E; Bulone, Vincent; Chowdhury, Jamil; Little, Alan; Burton, Rachel A; Bacic, Antony; Fincher, Geoffrey B; Schweizer, Patrick

2016-10-01

Cell walls and cellular turgor pressure shape and suspend the bodies of all vascular plants. In response to attack by fungal and oomycete pathogens, which usually breach their host's cell walls by mechanical force or by secreting lytic enzymes, plants often form local cell wall appositions (papillae) as an important first line of defence. The involvement of cell wall biosynthetic enzymes in the formation of these papillae is still poorly understood, especially in cereal crops. To investigate the role in plant defence of a candidate gene from barley (Hordeum vulgare) encoding cellulose synthase-like D2 (HvCslD2), we generated transgenic barley plants in which HvCslD2 was silenced through RNA interference (RNAi). The transgenic plants showed no growth defects but their papillae were more successfully penetrated by host-adapted, virulent as well as avirulent nonhost isolates of the powdery mildew fungus Blumeria graminis. Papilla penetration was associated with lower contents of cellulose in epidermal cell walls and increased digestion by fungal cell wall degrading enzymes. The results suggest that HvCslD2-mediated cell wall changes in the epidermal layer represent an important defence reaction both for nonhost and for quantitative host resistance against nonadapted wheat and host-adapted barley powdery mildew pathogens, respectively. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Pigmented epidermal cyst with dense collection of melanin: A rare entity – Report of a case with review of the literature

PubMed Central

Jayalakshmy, P. S.; Subitha, K.; Priya, P. V.; Johnson, Gerald

2012-01-01

Epidermal cyst is a very common benign cystic lesion of the skin. It is usual to find ulceration of the lining epithelium, rupture of the cyst wall with chronic inflammation and foreign body giant cell reaction. But, it is very rare to see an epidermal cyst with marked accumulation of melanin pigment. Only a few cases of pigmented epidermal cyst with dense collection of melanin pigment have been published in the literature. Here, we are reporting a case of ruptured epidermal cyst with keratin granuloma formation and showing dense collection of melanin pigment. PMID:23130289

Cell wall accumulation of fluorescent proteins derived from a trans-Golgi cisternal membrane marker and paramural bodies in interdigitated Arabidopsis leaf epidermal cells.

PubMed

Akita, Kae; Kobayashi, Megumi; Sato, Mayuko; Kutsuna, Natsumaro; Ueda, Takashi; Toyooka, Kiminori; Nagata, Noriko; Hasezawa, Seiichiro; Higaki, Takumi

2017-01-01

In most dicotyledonous plants, leaf epidermal pavement cells develop jigsaw puzzle-like shapes during cell expansion. The rapid growth and complicated cell shape of pavement cells is suggested to be achieved by targeted exocytosis that is coordinated with cytoskeletal rearrangement to provide plasma membrane and/or cell wall materials for lobe development during their morphogenesis. Therefore, visualization of membrane trafficking in leaf pavement cells should contribute an understanding of the mechanism of plant cell morphogenesis. To reveal membrane trafficking in pavement cells, we observed monomeric red fluorescent protein-tagged rat sialyl transferases, which are markers of trans-Golgi cisternal membranes, in the leaf epidermis of Arabidopsis thaliana. Quantitative fluorescence imaging techniques and immunoelectron microscopic observations revealed that accumulation of the red fluorescent protein occurred mostly in the curved regions of pavement cell borders and guard cell ends during leaf expansion. Transmission electron microscopy observations revealed that apoplastic vesicular membrane structures called paramural bodies were more frequent beneath the curved cell wall regions of interdigitated pavement cells and guard cell ends in young leaf epidermis. In addition, pharmacological studies showed that perturbations in membrane trafficking resulted in simple cell shapes. These results suggested possible heterogeneity of the curved regions of plasma membranes, implying a relationship with pavement cell morphogenesis.

Characterization of glycosylphosphatidylinositol-anchored lipid transfer protein 2 (LTPG2) and overlapping function between LTPG/LTPG1 and LTPG2 in cuticular wax export or accumulation in Arabidopsis thaliana.

PubMed

Kim, Hyojin; Lee, Saet Buyl; Kim, Hae Jin; Min, Myung Ki; Hwang, Inhwan; Suh, Mi Chung

2012-08-01

Cuticular waxes are synthesized by the extensive export of intracellular lipids from epidermal cells. However, it is still not known how hydrophobic cuticular lipids are exported to the plant surface through the hydrophilic cell wall. The LTPG2 gene was isolated based on Arabidopsis microarray analysis; this gene is predominantly expressed in stem epidermal peels as compared with in stems. The expression of LTPG2 transcripts was observed in various organs, including stem epidermis and silique walls. The composition of the cuticular wax was significantly altered in the stems and siliques of the ltpg2 mutant and ltpg1 ltpg2 double mutant. In particular, the reduced level of the C29 alkane, which is the major component of cuticular waxes in ltpg1 ltpg2 stems and siliques, was similar to the sum of reduced values of either parent. The total cuticular wax load was reduced by approximately 13% and 20% in both ltpg2 and ltpg1 ltpg2 siliques, respectively, and by approximately 14% in ltpg1 ltpg2 stems when compared with the wild-type. Similarly, severe alterations in the cuticular layer structure of epidermal cells of ltpg2 and ltpg1 ltpg2 stems and silique walls were observed. In tobacco epidermal cells, intracellular trafficking of the fluorescent LTPG/LTPG1 and LTPG2 to the plasma membrane was prevented by a dominant-negative mutant form of ADP-ribosylation factor 1, ARF1(T31N). Taken together, these results indicate that LTPG2 is functionally overlapped with LTPG/LTPG1 during cuticular wax export or accumulation and LTPG/LTPG1 and LTPG2 are targeted to the plasma membrane via the vesicular trafficking system.

A Developmental Framework for Complex Plasmodesmata Formation Revealed by Large-Scale Imaging of the Arabidopsis Leaf Epidermis[W

PubMed Central

Fitzgibbon, Jessica; Beck, Martina; Zhou, Ji; Faulkner, Christine; Robatzek, Silke; Oparka, Karl

2013-01-01

Plasmodesmata (PD) form tubular connections that function as intercellular communication channels. They are essential for transporting nutrients and for coordinating development. During cytokinesis, simple PDs are inserted into the developing cell plate, while during wall extension, more complex (branched) forms of PD are laid down. We show that complex PDs are derived from existing simple PDs in a pattern that is accelerated when leaves undergo the sink–source transition. Complex PDs are inserted initially at the three-way junctions between epidermal cells but develop most rapidly in the anisocytic complexes around stomata. For a quantitative analysis of complex PD formation, we established a high-throughput imaging platform and constructed PDQUANT, a custom algorithm that detected cell boundaries and PD numbers in different wall faces. For anticlinal walls, the number of complex PDs increased with increasing cell size, while for periclinal walls, the number of PDs decreased. Complex PD insertion was accelerated by up to threefold in response to salicylic acid treatment and challenges with mannitol. In a single 30-min run, we could derive data for up to 11k PDs from 3k epidermal cells. This facile approach opens the door to a large-scale analysis of the endogenous and exogenous factors that influence PD formation. PMID:23371949

Leaf Epidermis of the Rheophyte Dyckia brevifolia Baker (Bromeliaceae)

PubMed Central

Lobo, Ghislaine Maria; de Souza, Thaysi Ventura; Voltolini, Caroline Heinig; Reis, Ademir

2013-01-01

Some species of Dyckia Schult. f., including Dyckia brevifolia Baker, are rheophytes that live in the fast-moving water currents of streams and rivers which are subject to frequent flooding, but also period of low water. This study aimed to analyze the leaf epidermis of D. brevifolia in the context of epidermal adaptation to this aquatic plant's rheophytic habitat. The epidermis is uniseriate, and the cuticle is thickened. The inner periclinal and anticlinal walls of the epidermal cells are thickened and lignified. Stomata are tetracytic, located in the depressions in relation to the surrounding epidermal cells, and covered by peltate trichomes. While the epidermal characteristics of D. brevifolia are similar to those of Bromeliaceae species, this species has made particular adaptations of leaf epidermis in response to its rheophytic environment. PMID:23864825

Transient over-expression of barley BAX Inhibitor-1 weakens oxidative defence and MLA12-mediated resistance to Blumeria graminis f.sp. hordei.

PubMed

Eichmann, Ruth; Dechert, Cornelia; Kogel, Karl-Heinz; Hückelhoven, Ralph

2006-11-01

SUMMARY BAX Inhibitor-1 (BI-1) is a conserved cell death suppressor protein. In barley, BI-1 (HvBI-1) expression is induced upon powdery mildew infection and when over-expressed in epidermal cells of barley, HvBI-1 induces susceptibility to the biotrophic fungal pathogen Blumeria graminis. We co-expressed mammalian pro-apoptotic BAX together with HvBI-1, and the mammalian BAX antagonist BCL-X(L) in barley epidermal cells. BAX expression led to cessation of cytoplasmic streaming and collapse of the cytoplasm while co-expression of HvBI-1 and BCL-X(L) partially or completely, respectively, rescued cells from BAX lethality. When B. graminis was attacking epidermal cells, a green fluorescent protein fusion of HvBI-1 accumulated at the site of attempted penetration and was also present around haustoria. Over-expression of HvBI-1 in epidermal cells weakened a cell-wall-associated local hydrogen peroxide burst in a resistant mlo-mutant genotype and supported haustoria accommodation in race-specifically resistant MLA12-barley. HvBI-1 is a cell death regulator protein of barley with the potential to suppress host defence reactions.

Interactions with the actin cytoskeleton are required for cell wall localization of barley stripe mosaic virus TGB proteins

USDA-ARS?s Scientific Manuscript database

The host cytoskeleton and membrane system are the main routes by which plant viruses move within or between cells. Barley stripe mosaic virus (BSMV) -induced actin filament thickening was visualized in the cytoskeleton of agroinfiltrated Nicotiana benthamiana epidermal cells expressing DsRed:Talin. ...

Light-stimulated cell expansion in bean (Phaseolus vulgaris L.) leaves. I. Growth can occur without photosynthesis

NASA Technical Reports Server (NTRS)

Van Volkenburgh, E.; Cleland, R. E.

1990-01-01

Cell expansion in dicotyledonous leaves is strongly stimulated by bright white light (WL), at least in part as a result of light-induced acidification of the cell walls. It has been proposed that photosynthetic reactions are required for light-stimulated transport processes across plasma membranes of leaf cells, including proton excretion. The involvement of photosynthesis in growth and wall acidification of primary leaves of bean has been tested by inhibiting photosynthesis in two ways: by reducing chlorophyll content of intact plants with tentoxin (TX) and by treating leaf discs with 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). Exposure to bright WL stimulated growth of intact leaves of TX-treated plants. Discs excised from green as well as from TX-or DCMU-treated leaves also responded by growing faster in WL, as long as exogenous sucrose was supplied to the photosynthetically inhibited tissues. The WL caused acidification of the epidermal surface of intact TX-leaves, but acidification of the incubation medium by mesophyll cells only occurred when photosynthesis was not inhibited. It is concluded that light-stimulated cell enlargement of bean leaves, and the necessary acidification of epidermal cell walls, are mediated by a pigment other than chlorophyll. Light-induced proton excretion by mesophyll cells, on the other hand, may require both a photosynthetic product (or exogenous sugars) and a non-photosynthetic light effect.

Novel insights on the structure and composition of pseudostomata of Sphagnum.

PubMed

Merced, Amelia

2015-03-01

The occurrence of stomata on sporophytes of mosses and hornworts is congruent with a single origin in land plants. Although true stomata are absent in early-divergent mosses, Sphagnum has specialized epidermal cells, pseudostomata, that partially separate but do not open to the inside. This research examined two competing hypotheses that explain the origin of pseudostomata: (1) they are modified stomata, or (2) they evolved from epidermal cells independently from stomata.• Capsule anatomy and ultrastructure of pseudostomata were studied using light and electron microscopy, including immunolocalization of pectins.• Cell walls in pseudostomata are thin, two-layered, and rich in pectins, similar to young moss stomata, including the presence of cuticle on exterior walls. Outer and ventral walls have a thick cuticle that suggests that initial separation of ventral walls involves cuticle deposition as in true stomata. Further mechanical separation between ventral walls does not form a pore and occurs as the capsule dries.• As in moss stomata, pseudostomata wall architecture and behavior facilitate capsule dehydration, shape change, and dehiscence, supporting a common function. The divergent structure and fate of pseudostomata may be explained by the retention of Sphagnum sporophytes within protective leaves until nearly mature. Ultrastructural and immunocytological data suggest that pseudostomata are related to stomata but do not conclusively support either hypothesis. Solving the relationship of early land plants is critical to understanding stomatal evolution. Pseudostomata are structurally and anatomically unique, but their relationship to true stomata remains to be determined. © 2015 Botanical Society of America, Inc.

Carbon-concentrating mechanisms in seagrasses.

PubMed

Larkum, Anthony William D; Davey, Peter A; Kuo, John; Ralph, Peter J; Raven, John A

2017-06-01

Seagrasses are unique angiosperms that carry out growth and reproduction submerged in seawater. They occur in at least three families of the Alismatales. All have chloroplasts mainly in the cells of the epidermis. Living in seawater, the supply of inorganic carbon (Ci) to the chloroplasts is diffusion limited, especially under unstirred conditions. Therefore, the supply of CO2 and bicarbonate across the diffusive boundary layer on the outer side of the epidermis is often a limiting factor. Here we discuss the evidence for mechanisms that enhance the uptake of Ci into the epidermal cells. Since bicarbonate is plentiful in seawater, a bicarbonate pump might be expected; however, the evidence for such a pump is not strongly supported. There is evidence for a carbonic anhydrase outside the outer plasmalemma. This, together with evidence for an outward proton pump, suggests the possibility that local acidification leads to enhanced concentrations of CO2 adjacent to the outer tangential epidermal walls, which enhances the uptake of CO2, and this could be followed by a carbon-concentrating mechanism (CCM) in the cytoplasm and/or chloroplasts. The lines of evidence for such an epidermal CCM are discussed, including evidence for special 'transfer cells' in some but not all seagrass leaves in the tangential inner walls of the epidermal cells. It is concluded that seagrasses have a CCM but that the case for concentration of CO2 at the site of Rubisco carboxylation is not proven. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Vesicles between plasma membrane and cell wall prior to visible senescence of Iris and Dendrobium flowers.

PubMed

Kamdee, Channatika; Kirasak, Kanjana; Ketsa, Saichol; van Doorn, Wouter G

2015-09-01

Cut Iris flowers (Iris x hollandica, cv. Blue Magic) show visible senescence about two days after full opening. Epidermal cells of the outer tepals collapse due to programmed cell death (PCD). Transmission electron microscopy (TEM) showed irregular swelling of the cell walls, starting prior to cell collapse. Compared to cells in flowers that had just opened, wall thickness increased up to tenfold prior to cell death. Fibrils were visible in the swollen walls. After cell death very little of the cell wall remained. Prior to and during visible wall swelling, vesicles (paramural bodies) were observed between the plasma membrane and the cell walls. The vesicles were also found in groups and were accompanied by amorphous substance. They usually showed a single membrane, and had a variety of diameters and electron densities. Cut Dendrobium hybrid cv. Lucky Duan flowers exhibited visible senescence about 14 days after full flower opening. Paramural bodies were also found in Dendrobium tepal epidermis and mesophyll cells, related to wall swelling and degradation. Although alternative explanations are well possible, it is hypothesized that paramural bodies carry enzymes involved in cell wall breakdown. The literature has not yet reported such bodies in association with senescence/PCD. Copyright © 2015 Elsevier GmbH. All rights reserved.

Resistance to Botrytis cinerea in sitiens, an Abscisic Acid-Deficient Tomato Mutant, Involves Timely Production of Hydrogen Peroxide and Cell Wall Modifications in the Epidermis1[C][W][OA

PubMed Central

Asselbergh, Bob; Curvers, Katrien; França, Soraya C.; Audenaert, Kris; Vuylsteke, Marnik; Van Breusegem, Frank; Höfte, Monica

2007-01-01

Plant defense mechanisms against necrotrophic pathogens, such as Botrytis cinerea, are considered to be complex and to differ from those that are effective against biotrophs. In the abscisic acid-deficient sitiens tomato (Solanum lycopersicum) mutant, which is highly resistant to B. cinerea, accumulation of hydrogen peroxide (H2O2) was earlier and stronger than in the susceptible wild type at the site of infection. In sitiens, H2O2 accumulation was observed from 4 h postinoculation (hpi), specifically in the leaf epidermal cell walls, where it caused modification by protein cross-linking and incorporation of phenolic compounds. In wild-type tomato plants, H2O2 started to accumulate 24 hpi in the mesophyll layer and was associated with spreading cell death. Transcript-profiling analysis using TOM1 microarrays revealed that defense-related transcript accumulation prior to infection was higher in sitiens than in wild type. Moreover, further elevation of sitiens defense gene expression was stronger than in wild type 8 hpi both in number of genes and in their expression levels and confirmed a role for cell wall modification in the resistant reaction. Although, in general, plant defense-related reactive oxygen species formation facilitates necrotrophic colonization, these data indicate that timely hyperinduction of H2O2-dependent defenses in the epidermal cell wall can effectively block early development of B. cinerea. PMID:17573540

Rumen Bacterial Degradation of Forage Cell Walls Investigated by Electron Microscopy

PubMed Central

Akin, Danny E.; Amos, Henry E.

1975-01-01

The association of rumen bacteria with specific leaf tissues of the forage grass Kentucky-31 tall fescue (Festuca arundinacea Schreb.) during in vitro degradation was investigated by transmission and scanning electron microscopy. Examination of degraded leaf cross-sections revealed differential rates of tissue degradation in that the cell walls of the mesophyll and pholem were degraded prior to those of the outer bundle sheath and epidermis. Rumen bacteria appeared to degrade the mesophyll, in some cases, and phloem without prior attachment to the plant cell walls. The degradation of bundle sheath and epidermal cell walls appeared to be preceded by attachment of bacteria to the plant cell wall. Ultrastructural features apparently involved in the adhesion of large cocci to plant cells were observed by transmission and scanning electron microscopy. The physical association between plant and rumen bacterial cells during degradation apparently varies with tissue types. Bacterial attachment, by extracellular features in some microorganisms, is required prior to degradation of the more resistant tissues. Images PMID:16350017

Imaging and quantitative data acquisition of biological cell walls with Atomic Force Microscopy and Scanning Acoustic Microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tittmann, B. R.; Xi, X.

This chapter demonstrates the feasibility of Atomic Force Microscopy (AFM) and High Frequency Scanning Acoustic Microscopy (HF-SAM) as tools to characterize biological tissues. Both the AFM and the SAM have shown to provide imaging (with different resolution) and quantitative elasticity measuring abilities. Plant cell walls with minimal disturbance and under conditions of their native state have been examined with these two kinds of microscopy. After descriptions of both the SAM and AFM, their special features and the typical sample preparation is discussed. The sample preparation is focused here on epidermal peels of onion scales and celery epidermis cells which weremore » sectioned for the AFM to visualize the inner surface (closest to the plasma membrane) of the outer epidermal wall. The nm-wide cellulose microfibrils orientation and multilayer structure were clearly observed. The microfibril orientation and alignment tend to be more organized in older scales compared with younger scales. The onion epidermis cell wall was also used as a test analog to study cell wall elasticity by the AFM nanoindentation and the SAM V(z) feature. The novelty in this work was to demonstrate the capability of these two techniques to analyze isolated, single layered plant cell walls in their natural state. AFM nanoindentation was also used to probe the effects of Ethylenediaminetetraacetic acid (EDTA), and calcium ion treatment to modify pectin networks in cell walls. The results suggest a significant modulus increase in the calcium ion treatment and a slight decrease in EDTA treatment. To complement the AFM measurements, the HF-SAM was used to obtain the V(z) signatures of the onion epidermis. These measurements were focused on documenting the effect of pectinase enzyme treatment. The results indicate a significant change in the V(z) signature curves with time into the enzyme treatment. Thus AFM and HF-SAM open the door to a systematic nondestructive structure and mechanical property study of complex biological cell walls. A unique feature of this approach is that both microscopes allow the biological samples to be examined in their natural fluid (water) environment.« less

Developmental and Tissue-Specific Structural Alterations of the Cell-Wall Polysaccharides of Arabidopsis thaliana Roots.

PubMed Central

Freshour, G.; Clay, R. P.; Fuller, M. S.; Albersheim, P.; Darvill, A. G.; Hahn, M. G.

1996-01-01

The plant cell wall is a dynamic structure that plays important roles in growth and development and in the interactions of plants with their environment and other organisms. We have used monoclonal antibodies that recognize different carbohydrate epitopes present in plant cell-wall polysaccharides to locate these epitopes in roots of developing Arabidopsis thaliana seedlings. An epitope in the pectic polysaccharide rhamnogalacturonan I is observed in the walls of epidermal and cortical cells in mature parts of the root. This epitope is inserted into the walls in a developmentally regulated manner. Initially, the epitope is observed in atrichoblasts and later appears in trichoblasts and simultaneously in cortical cells. A terminal [alpha]-fucosyl-containing epitope is present in almost all of the cell walls in the root. An arabinosylated (1->6)-[beta]-galactan epitope is also found in all of the cell walls of the root with the exception of lateral root-cap cell walls. It is striking that these three polysaccharide epitopes are not uniformly distributed (or accessible) within the walls of a given cell, nor are these epitopes distributed equally across the two walls laid down by adjacent cells. Our results further suggest that the biosynthesis and differentiation of primary cell walls in plants are precisely regulated in a temporal, spatial, and developmental manner. PMID:12226270

Cellular basis of gravity resistance in plants

NASA Astrophysics Data System (ADS)

Hoson, Takayuki; Matsumoto, Shouhei; Inui, Kenichi; Zhang, Yan; Soga, Kouichi; Wakabayashi, Kazuyuki; Hashimoto, Takashi

Mechanical resistance to the gravitational force is a principal gravity response in plants distinct from gravitropism. In the final step of gravity resistance, plants increase the rigidity of their cell walls via modifications to the cell wall metabolism and apoplastic environment. We studied cellular events that are related to the cell wall changes under hypergravity conditions produced by centrifugation. Hypergravity induced reorientation of cortical microtubules from transverse to longitudinal directions in epidermal cells of stem organs. In Arabidopsis tubulin mutants, the percentage of cells with longitudinal microtubules was high even at 1 g, and it was further increased by hypergravity. Hypocotyls of tubulin mutants also showed either left-handed or right-handed helical growth at 1 g, and the degree of twisting phenotype was intensified under hypergravity conditions. The left-handed helical growth mutants had right-handed microtubule arrays, whereas the right-handed mutant had left-handed arrays. There was a close correlation between the alignment angle of epidermal cell files and the alignment of cortical microtubules. Gadolinium ions suppressed both the twisting phenotype and reorientation of microtubules in tubulin mutants. These results support the hypothesis that cortical microtubules play an es-sential role in maintenance of normal growth phenotype against the gravitational force, and suggest that mechanoreceptors are involved in modifications to morphology and orientation of microtubule arrays by hypergravity. Actin microfilaments, in addition to microtubules, may be involved in gravity resistance. The nucleus of epidermal cells of azuki bean epicotyls, which is present almost in the center of the cell at 1 g, was displaced to the cell bottom by increasing the magnitude of gravity. Cytochalasin D stimulated the sedimentation by hypergravity of the nu-cleus, suggesting that the positioning of the nucleus is regulated by actin microfilaments, which is affected by gravity. We also examined the effects of hypergravity on the osmotic properties of azuki bean epicotyls, and found that epicotyls were capable of maintaining osmoregulation even under hypergravity conditions at least for a short period. The increase in level of total osmotic solutes was suppressed by long-term hypergravity treatment, which was accounted by suppres-sion of translocation of organic solutes such as sugars and amino acids. These various cellular events may contribute to sustaining the cell wall changes or cooperate with the cell wall in gravity resistance. Space experiments on the International Space Station will confirm whether this view is applicable to plant resistance to 1 g gravity, as to the resistance to hypergravity.

Multiscale Investigation from Subcellular to Tissue Scale of Onion Epidermal Plant Cell Wall Mechanical Properties

NASA Astrophysics Data System (ADS)

Zamil, Mohammad Shafayet

The physical and mechanical properties of cell walls, their shape, how they are arranged and interact with each other determine the architecture of plant organs and how they mechanically respond to different environmental and loading conditions. Due to the distinctive hierarchy from subcellular to tissue scale, plant materials can exhibit remarkably different mechanical properties. To date, how the subcellular scale arrangement and the mechanical properties of plant cell wall structural constituents give rise to macro or tissue scale mechanical responses is not yet well understood. Although the tissue scale plant cell wall samples are easy to prepare and put to different types of mechanical tests, the hierarchical features that emerge when moving towards a higher scale make it complicated to link the macro scale results to micro or subcellular scale structural components. On the other hand, the microscale size of cell brings formidable challenges to prepare and grip samples and carry mechanical tests under tensile loading at subcellular scale. This study attempted to develop a set of test protocols based on microelectromechanical system (MEMS) tensile testing devices for characterizing plant cell wall materials at different length scales. For the ease of sample preparation and well established database of the composition and conformation of its structural constituents, onion epidermal cell wall profile was chosen as the study material. Based on the results and findings of multiscale mechanical characterization, a framework of architecture-based finite element method (FEM) computational model was developed. The computational model laid the foundation of bridging the subcellular or microscale to the tissue or macroscale mechanical properties. This study suggests that there are important insights of cell wall mechanics and structural features that can only be investigated by carrying tensile characterization of samples not confounded by extracellular parameters. To the best of our knowledge, the plant cell wall at subcellular scale was never characterized under tensile loading. By coupling the structure based multiscale modeling and mechanical characterizations at different length scales, an attempt was made to provide novel insights towards understanding the mechanics and architecture of cell wall. This study also suggests that a multiscale investigation is essential for garnering fundamental insights into the hierarchical deformation of biological systems.

Characteristic thickened cell walls of the bracts of the 'eternal flower' Helichrysum bracteatum.

PubMed

Nishikawa, Kuniko; Ito, Hiroaki; Awano, Tatsuya; Hosokawa, Munetaka; Yazawa, Susumu

2008-07-01

Helichrysum bracteatum is called an 'eternal flower' and has large, coloured, scarious bracts. These maintain their aesthetic value without wilting or discoloration for many years. There have been no research studies of cell death or cell morphology of the scarious bract, and hence the aim of this work was to elucidate these characteristics for the bract of H. bracteatum. DAPI (4'6-diamidino-2-phenylindol dihydrochloride) staining and fluorescence microscopy were used for observation of cell nuclei. Light microscopy (LM), transmission electron microscopy (TEM) and polarized light microscopy were used for observation of cells, including cell wall morphology. Cell death occurred at the bract tip during the early stage of flower development. The cell wall was the most prominent characteristic of H. bracteatum bract cells. Characteristic thickened secondary cell walls on the inside of the primary cell walls were observed in both epidermal and inner cells. In addition, the walls of all cells exhibited birefringence. Characteristic thickened secondary cell walls have orientated cellulose microfibrils as well as general secondary cell walls of the tracheary elements. For comparison, these characters were not observed in the petal and bract tissues of Chrysanthemum morifolium. Bracts at anthesis are composed of dead cells. Helichrysum bracteatum bracts have characteristic thickened secondary cell walls that have not been observed in the parenchyma of any other flowers or leaves. The cells of the H. bracteatum bract differ from other tissues with secondary cell walls, suggesting that they may be a new cell type.

The growing outer epidermal wall: design and physiological role of a composite structure.

PubMed

Kutschera, U

2008-04-01

The cells of growing plant organs secrete an extracellular fibrous composite (the primary wall) that allows the turgid protoplasts to expand irreversibly via wall-yielding events, which are regulated by processes within the cytoplasm. The role of the epidermis in the control of stem elongation is described with special reference to the outer epidermal wall (OEW), which forms a 'tensile skin'. The OEW is much thicker and less extensible than the walls of the inner tissues. Moreover, in the OEW the amount of cellulose per unit wall mass is considerably greater than in the inner tissues. Ultrastructural studies have shown that the expanding OEW is composed of a highly ordered internal and a diffuse outer half, with helicoidally organized cellulose microfibrils in the inner (load-bearing) region of this tension-stressed organ wall. The structural and mechanical backbone of the wall consists of helicoids, i.e. layers of parallel, inextensible cellulose microfibrils. These 'plywood laminates' contain crystalline 'cables' orientated in all directions with respect to the axis of elongation (isotropic material). Cessation of cell elongation is accompanied by a loss of order, i.e. the OEW is a dynamic structure. Helicoidally arranged extracellular polymers have also been found in certain bacteria, algae, fungi and animals. In the insect cuticle crystalline cutin nanofibrils form characteristic 'OEW-like' herringbone patterns. Theoretical considerations, in vitro studies and computer simulations suggest that extracellular biological helicoids form by directed self-assembly of the crystalline biopolymers. This spontaneous generation of complex design 'without an intelligent designer' evolved independently in the protective 'skin' of plants, animals and many other organisms.

Cotton fiber tips have diverse morphologies and show evidence of apical cell wall synthesis

PubMed Central

Stiff , Michael R.; Haigler, Candace H.

2016-01-01

Cotton fibers arise through highly anisotropic expansion of a single seed epidermal cell. We obtained evidence that apical cell wall synthesis occurs through examining the tips of young elongating Gossypium hirsutum (Gh) and G. barbadense (Gb) fibers. We characterized two tip types in Gh fiber (hemisphere and tapered), each with distinct apical diameter, central vacuole location, and distribution of cell wall components. The apex of Gh hemisphere tips was enriched in homogalacturonan epitopes, including a relatively high methyl-esterified form associated with cell wall pliability. Other wall components increased behind the apex including cellulose and the α-Fuc-(1,2)-β-Gal epitope predominantly found in xyloglucan. Gb fibers had only one narrow tip type featuring characters found in each Gh tip type. Pulse-labeling of cell wall glucans indicated wall synthesis at the apex of both Gh tip types and in distal zones. Living Gh hemisphere and Gb tips ruptured preferentially at the apex upon treatment with wall degrading enzymes, consistent with newly synthesized wall at the apex. Gh tapered tips ruptured either at the apex or distantly. Overall, the results reveal diverse cotton fiber tip morphologies and support primary wall synthesis occurring at the apex and discrete distal regions of the tip. PMID:27301434

Transient gibberellin application promotes Arabidopsis thaliana hypocotyl cell elongation without maintaining transverse orientation of microtubules on the outer tangential wall of epidermal cells.

PubMed

Sauret-Güeto, Susanna; Calder, Grant; Harberd, Nicholas P

2012-02-01

The phytohormone gibberellin (GA) promotes plant growth by stimulating cellular expansion. Whilst it is known that GA acts by opposing the growth-repressing effects of DELLA proteins, it is not known how these events promote cellular expansion. Here we present a time-lapse analysis of the effects of a single pulse of GA on the growth of Arabidopsis hypocotyls. Our analyses permit kinetic resolution of the transient growth effects of GA on expanding cells. We show that pulsed application of GA to the relatively slowly growing cells of the unexpanded light-grown Arabidopsis hypocotyl results in a transient burst of anisotropic cellular growth. This burst, and the subsequent restoration of initial cellular elongation rates, occurred respectively following the degradation and subsequent reappearance of a GFP-tagged DELLA (GFP-RGA). In addition, we used a GFP-tagged α-tubulin 6 (GFP-TUA6) to visualise the behaviour of microtubules (MTs) on the outer tangential wall (OTW) of epidermal cells. In contrast to some current hypotheses concerning the effect of GA on MTs, we show that the GA-induced boost of hypocotyl cell elongation rate is not dependent upon the maintenance of transverse orientation of the OTW MTs. This confirms that transverse alignment of outer face MTs is not necessary to maintain rapid elongation rates of light-grown hypocotyls. Together with future studies on MT dynamics in other faces of epidermal cells and in cells deeper within the hypocotyl, our observations advance understanding of the mechanisms by which GA promotes plant cell and organ growth. © 2011 The Authors. The Plant Journal © 2011 Blackwell Publishing Ltd.

Silicification in Grasses: Variation between Different Cell Types

PubMed Central

Kumar, Santosh; Soukup, Milan; Elbaum, Rivka

2017-01-01

Plants take up silicon as mono-silicic acid, which is released to soil by the weathering of silicate minerals. Silicic acid can be taken up by plant roots passively or actively, and later it is deposited in its polymerized form as amorphous hydrated silica. Major silica depositions in grasses occur in root endodermis, leaf epidermal cells, and outer epidermal cells of inflorescence bracts. Debates are rife about the mechanism of silica deposition, and two contrasting scenarios are often proposed to explain it. According to the passive mode of silicification, silica deposition is a result of silicic acid condensation due to dehydration, such as during transpirational loss of water from the aboveground organs. In general, silicification and transpiration are positively correlated, and continued silicification is sometimes observed after cell and tissue maturity. The other mode of silicification proposes the involvement of some biological factors, and is based on observations that silicification is not necessarily coupled with transpiration. Here, we review evidence for both mechanisms of silicification, and propose that the deposition mechanism is specific to the cell type. Considering all the cell types together, our conclusion is that grass silica deposition can be divided into three modes: spontaneous cell wall silicification, directed cell wall silicification, and directed paramural silicification in silica cells. PMID:28400787

Stomatal Complex Development and F-Actin Organization in Maize Leaf Epidermis Depend on Cellulose Synthesis.

PubMed

Panteris, Emmanuel; Achlati, Theonymphi; Daras, Gerasimos; Rigas, Stamatis

2018-06-06

Cellulose microfibrils reinforce the cell wall for morphogenesis in plants. Herein, we provide evidence on a series of defects regarding stomatal complex development and F-actin organization in Zea mays leaf epidermis, due to inhibition of cellulose synthesis. Formative cell divisions of stomatal complex ontogenesis were delayed or inhibited, resulting in lack of subsidiary cells and frequently in unicellular stomata, with an atypical stomatal pore. Guard cells failed to acquire a dumbbell shape, becoming rounded, while subsidiary cells, whenever present, exhibited aberrant morphogenesis. F-actin organization was also affected, since the stomatal complex-specific arrays were scarcely observed. At late developmental stages, the overall F-actin network was diminished in all epidermal cells, although thick actin bundles persisted. Taken together, stomatal complex development strongly depends on cell wall mechanical properties. Moreover, F-actin organization exhibits a tight relationship with the cell wall.

Characteristic Thickened Cell Walls of the Bracts of the ‘Eternal Flower’ Helichrysum bracteatum

PubMed Central

Nishikawa, Kuniko; Ito, Hiroaki; Awano, Tatsuya; Hosokawa, Munetaka; Yazawa, Susumu

2008-01-01

Background and Aims Helichrysum bracteatum is called an ‘eternal flower’ and has large, coloured, scarious bracts. These maintain their aesthetic value without wilting or discoloration for many years. There have been no research studies of cell death or cell morphology of the scarious bract, and hence the aim of this work was to elucidate these characteristics for the bract of H. bracteatum. Methods DAPI (4'6-diamidino-2-phenylindol dihydrochloride) staining and fluorescence microscopy were used for observation of cell nuclei. Light microscopy (LM), transmission electron microscopy (TEM) and polarized light microscopy were used for observation of cells, including cell wall morphology. Key Results Cell death occurred at the bract tip during the early stage of flower development. The cell wall was the most prominent characteristic of H. bracteatum bract cells. Characteristic thickened secondary cell walls on the inside of the primary cell walls were observed in both epidermal and inner cells. In addition, the walls of all cells exhibited birefringence. Characteristic thickened secondary cell walls have orientated cellulose microfibrils as well as general secondary cell walls of the tracheary elements. For comparison, these characters were not observed in the petal and bract tissues of Chrysanthemum morifolium. Conclusions Bracts at anthesis are composed of dead cells. Helichrysum bracteatum bracts have characteristic thickened secondary cell walls that have not been observed in the parenchyma of any other flowers or leaves. The cells of the H. bracteatum bract differ from other tissues with secondary cell walls, suggesting that they may be a new cell type. PMID:18436550

Quantifying Hydrostatic Pressure in Plant Cells by Using Indentation with an Atomic Force Microscope

PubMed Central

Beauzamy, Léna; Derr, Julien; Boudaoud, Arezki

2015-01-01

Plant cell growth depends on a delicate balance between an inner drive—the hydrostatic pressure known as turgor—and an outer restraint—the polymeric wall that surrounds a cell. The classical technique to measure turgor in a single cell, the pressure probe, is intrusive and cannot be applied to small cells. In order to overcome these limitations, we developed a method that combines quantification of topography, nanoindentation force measurements, and an interpretation using a published mechanical model for the pointlike loading of thin elastic shells. We used atomic force microscopy to estimate the elastic properties of the cell wall and turgor pressure from a single force-depth curve. We applied this method to onion epidermal peels and quantified the response to changes in osmolality of the bathing solution. Overall our approach is accessible and enables a straightforward estimation of the hydrostatic pressure inside a walled cell. PMID:25992723

CLD1/SRL1 modulates leaf rolling by affecting cell wall formation, epidermis integrity and water homeostasis in rice.

PubMed

Li, Wen-Qiang; Zhang, Min-Juan; Gan, Peng-Fei; Qiao, Lei; Yang, Shuai-Qi; Miao, Hai; Wang, Gang-Feng; Zhang, Mao-Mao; Liu, Wen-Ting; Li, Hai-Feng; Shi, Chun-Hai; Chen, Kun-Ming

2017-12-01

Leaf rolling is considered as one of the most important agronomic traits in rice breeding. It has been previously reported that SEMI-ROLLED LEAF 1 (SRL1) modulates leaf rolling by regulating the formation of bulliform cells in rice (Oryza sativa); however, the regulatory mechanism underlying SRL1 has yet to be further elucidated. Here, we report the functional characterization of a novel leaf-rolling mutant, curled leaf and dwarf 1 (cld1), with multiple morphological defects. Map-based cloning revealed that CLD1 is allelic with SRL1, and loses function in cld1 through DNA methylation. CLD1/SRL1 encodes a glycophosphatidylinositol (GPI)-anchored membrane protein that modulates leaf rolling and other aspects of rice growth and development. The cld1 mutant exhibits significant decreases in cellulose and lignin contents in secondary cell walls of leaves, indicating that the loss of function of CLD1/SRL1 affects cell wall formation. Furthermore, the loss of CLD1/SRL1 function leads to defective leaf epidermis such as bulliform-like epidermal cells. The defects in leaf epidermis decrease the water-retaining capacity and lead to water deficits in cld1 leaves, which contribute to the main cause of leaf rolling. As a result of the more rapid water loss and lower water content in leaves, cld1 exhibits reduced drought tolerance. Accordingly, the loss of CLD1/SRL1 function causes abnormal expression of genes and proteins associated with cell wall formation, cuticle development and water stress. Taken together, these findings suggest that the functional roles of CLD1/SRL1 in leaf-rolling regulation are closely related to the maintenance of cell wall formation, epidermal integrity and water homeostasis. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

Sticking to cellulose: exploiting Arabidopsis seed coat mucilage to understand cellulose biosynthesis and cell wall polysaccharide interactions.

PubMed

Griffiths, Jonathan S; North, Helen M

2017-05-01

The cell wall defines the shape of cells and ultimately plant architecture. It provides mechanical resistance to osmotic pressure while still being malleable and allowing cells to grow and divide. These properties are determined by the different components of the wall and the interactions between them. The major components of the cell wall are the polysaccharides cellulose, hemicellulose and pectin. Cellulose biosynthesis has been extensively studied in Arabidopsis hypocotyls, and more recently in the mucilage-producing epidermal cells of the seed coat. The latter has emerged as an excellent system to study cellulose biosynthesis and the interactions between cellulose and other cell wall polymers. Here we review some of the major advances in our understanding of cellulose biosynthesis in the seed coat, and how mucilage has aided our understanding of the interactions between cellulose and other cell wall components required for wall cohesion. Recently, 10 genes involved in cellulose or hemicellulose biosynthesis in mucilage have been identified. These discoveries have helped to demonstrate that xylan side-chains on rhamnogalacturonan I act to link this pectin directly to cellulose. We also examine other factors that, either directly or indirectly, influence cellulose organization or crystallization in mucilage. © 2017 INRA. New Phytologist © 2017 New Phytologist Trust.

Analysis of cell division patterns in the Arabidopsis shoot apical meristem

DOE PAGES

Shapiro, Bruce E.; Tobin, Cory; Mjolsness, Eric; ...

2015-03-30

The stereotypic pattern of cell shapes in the Arabidopsis shoot apical meristem (SAM) suggests that strict rules govern the placement of new walls during cell division. When a cell in the SAM divides, a new wall is built that connects existing walls and divides the cytoplasm of the daughter cells. Because features that are determined by the placement of new walls such as cell size, shape, and number of neighbors are highly regular, rules must exist for maintaining such order. Here in this paper we present a quantitative model of these rules that incorporates different observed features of cell division.more » Each feature is incorporated into a "potential function" that contributes a single term to a total analog of potential energy. New cell walls are predicted to occur at locations where the potential function is minimized. Quantitative terms that represent the well-known historical rules of plant cell division, such as those given by Hofmeister, Errera, and Sachs are developed and evaluated against observed cell divisions in the epidermal layer (L1) of Arabidopsis thaliana SAM. The method is general enough to allow additional terms for nongeometric properties such as internal concentration gradients and mechanical tensile forces.« less

Genetic diversity of root anatomy in wild and cultivated Manihot species.

PubMed

Bomfim, N N; Graciano-Ribeiro, D; Nassar, N M A

2011-04-05

An anatomical study of roots was conducted on two wild Manihot species, namely M. glaziovii and M. fortalezensis, and two cassava varieties, M. esculenta Crantz variety UnB 201 and M. esculenta variety UnB 122, to identify taxonomic differences in primary growth. Anatomical characters of cassava roots have been rarely investigated. Their study may help cassava breeders to identify varieties with economically important characters, such as tolerance to drought. We investigated tap and lateral adventitious roots of two specimens of each clone or species. Free-hand cross-sections of roots were drawn; these had been clarified with 20% sodium hypochlorite solution, stained with 1% safranin-alcian blue ethanolic solution, dehydrated in ethanol series and butyl acetate and mounted in synthetic resin. Anatomical differences among Manihot species and varieties were found in the epidermal and exodermal cell shape and wall thickness, content of cortical parenchyma, and number of xylem poles. Wall thickness of the epidermis and exodermis of tap root were similar in all species, while in the lateral root there were differences in cell shape and wall thickness. Epidermal cells with thick walls were found in the tap root of all species and in lateral roots of cassava varieties. This character is apparently associated with tolerance to drought and disease. The variation in the number of xylem poles of cassava varieties was larger (4-8) than in wild species (4-6), and appears to support the hybrid origin of cassava.

Identification and expression analysis of BoMF25, a novel polygalacturonase gene involved in pollen development of Brassica oleracea.

PubMed

Lyu, Meiling; Liang, Ying; Yu, Youjian; Ma, Zhiming; Song, Limin; Yue, Xiaoyan; Cao, Jiashu

2015-06-01

BoMF25 acts on pollen wall. Polygalacturonase (PG) is a pectin-digesting enzyme involved in numerous plant developmental processes and is described to be of critical importance for pollen wall development. In the present study, a PG gene, BoMF25, was isolated from Brassica oleracea. BoMF25 is the homologous gene of At4g35670, a PG gene in Arabidopsis thaliana with a high expression level at the tricellular pollen stage. Collinear analysis revealed that the orthologous gene of BoMF25 in Brassica campestris (syn. B. rapa) genome was probably lost because of genome deletion and reshuffling. Sequence analysis indicated that BoMF25 contained four classical conserved domains (I, II, III, and IV) of PG protein. Homology and phylogenetic analyses showed that BoMF25 was clustered in Clade F. The putative promoter sequence, containing classical cis-acting elements and pollen-specific motifs, could drive green fluorescence protein expression in onion epidermal cells. Quantitative RT-PCR analysis suggested that BoMF25 was mainly expressed in the anther at the late stage of pollen development. In situ hybridization analysis also indicated that the strong and specific expression signal of BoMF25 existed in pollen grains at the mature pollen stage. Subcellular localization showed that the fluorescence signal was observed in the cell wall of onion epidermal cells, which suggested that BoMF25 may be a secreted protein localized in the pollen wall.

Mutation in xyloglucan 6-xylosytransferase results in abnormal root hair development in Oryza sativa

PubMed Central

Wang, Chuang; Li, Shuai; Ng, Sophia; Zhang, Baocai; Zhou, Yihua; Whelan, James; Wu, Ping; Shou, Huixia

2014-01-01

Root hairs are important for nutrient uptake, anchorage, and plant–microbe interactions. From a population of rice (Oryza sativa) mutagenized by ethyl methanesulfonate (EMS), a short root hair2 (srh2) mutant was identified. In hydroponic culture, srh2 seedlings were significantly reduced in root hair length. Bubble-like extrusions and irregular epidermal cells were observed at the tips of srh2 root hairs when grown under acidic conditions, suggesting the possible reduction of the tensile strength of the cell wall in this mutant. Map-based cloning identified a mutation in the gene encoding xyloglucan (XyG) 6-xylosyltransferase (OsXXT1). OsXXT1 displays more than 70% amino acid sequence identity with the previously characterized Arabidopsis thaliana XYG XYLOSYL TRANSFERASE 1 (AtXXT1) and XYG XYLOSYL TRANSFERASE 2 (AtXXT2), which catalyse the transfer of xylose onto β-1,4-glucan chains. Furthermore, expression of the full-length coding sequence of OsXXT1 could complement the root hair defect, and slow growth and XyG synthesis in the Arabidopsis xxt1 xxt2 double mutant. Transgenic plants expressing the β-glucuronidase (GUS) reporter under the control of the OsXXT1 promoter displayed GUS expression in multiple tissues, most prominently in root epidermal cells. These results demonstrate the importance of OsXXT1 in maintaining cell wall structure and tensile strength in rice, a typical grass species that contains relatively low XyG content in cell walls. PMID:24834920

Downregulation of the Petunia hybrida alpha-expansin gene PhEXP1 reduces the amount of crystalline cellulose in cell walls and leads to phenotypic changes in petal limbs.

PubMed

Zenoni, Sara; Reale, Lara; Tornielli, Giovanni Battista; Lanfaloni, Luisa; Porceddu, Andrea; Ferrarini, Alberto; Moretti, Chiaraluce; Zamboni, Anita; Speghini, Adolfo; Ferranti, Francesco; Pezzotti, Mario

2004-02-01

The expansins comprise a family of proteins that appear to be involved in the disruption of the noncovalent bonds between cellulose microfibrils and cross-linking glycans, thereby promoting wall creep. To understand better the expansion process in Petunia hybrida (petunia) flowers, we isolated a cDNA corresponding to the PhEXP1 alpha-expansin gene of P. hybrida. Evaluation of the tissue specificity and temporal expression pattern demonstrated that PhEXP1 is preferentially expressed in petal limbs during development. To determine the function of PhEXP1, we used a transgenic antisense approach, which was found to cause a decrease in petal limb size, a reduction in the epidermal cell area, and alterations in cell wall morphology and composition. The diminished cell wall thickness accompanied by a reduction in crystalline cellulose indicates that the activity of PhEXP1 is associated with cellulose metabolism. Our results suggest that expansins play a role in the assembly of the cell wall by affecting either cellulose synthesis or deposition.

Downregulation of the Petunia hybrida α-Expansin Gene PhEXP1 Reduces the Amount of Crystalline Cellulose in Cell Walls and Leads to Phenotypic Changes in Petal Limbs

PubMed Central

Zenoni, Sara; Reale, Lara; Tornielli, Giovanni Battista; Lanfaloni, Luisa; Porceddu, Andrea; Ferrarini, Alberto; Moretti, Chiaraluce; Zamboni, Anita; Speghini, Adolfo; Ferranti, Francesco; Pezzotti, Mario

2004-01-01

The expansins comprise a family of proteins that appear to be involved in the disruption of the noncovalent bonds between cellulose microfibrils and cross-linking glycans, thereby promoting wall creep. To understand better the expansion process in Petunia hybrida (petunia) flowers, we isolated a cDNA corresponding to the PhEXP1 α-expansin gene of P. hybrida. Evaluation of the tissue specificity and temporal expression pattern demonstrated that PhEXP1 is preferentially expressed in petal limbs during development. To determine the function of PhEXP1, we used a transgenic antisense approach, which was found to cause a decrease in petal limb size, a reduction in the epidermal cell area, and alterations in cell wall morphology and composition. The diminished cell wall thickness accompanied by a reduction in crystalline cellulose indicates that the activity of PhEXP1 is associated with cellulose metabolism. Our results suggest that expansins play a role in the assembly of the cell wall by affecting either cellulose synthesis or deposition. PMID:14742876

Effect of diesel exhaust pollution on cuticular and epidermal features of Lantana camara L. and Syzygium cuminii L. (Skeels. )

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kulshreshtha, K.; Farooqui, A.; Srivastava, K.

1994-02-01

Cuticular and epidermal features of leaves of two common plant species namely, Lantana camara L. and Syzygium cuminii L. (Skeel.) growing in polluted and healthy (control) environments were studied under light and scanning electron microscopes. Polluted leaf samples were collected from the plants growing near a diesel generating set used in running a tube well. The study shows that in polluted populations of Lantana camara, the trichome frequency had increased four fold. In Syzygium cuminii, the stomatal openings were filled with dust and a tendency towards callus formation was also observed. The epidermal cells were comparatively thick walled and weremore » broken at certain places. The changes observed in the cuticular and epidermal features of polluted populations of the investigated species indicate their significance as bioindicators of atmospheric pollution. 9 refs., 2 figs., 1 tab.« less

Ontogenetic characterization of sporangium and spore of Huperzia serrata: an anti-aging disease fern.

PubMed

Long, Hua; Li, Jing; Li, You-You; Xie, De-Yu; Peng, Qing-Zhong; Li, Li

2016-12-01

Huperzia serrata is a medicinal plant used in Traditional Chinese Medicine, which has been used to prevent against aging diseases. It is mainly propagated by spores and grows extremely slowly. Due to severe harvest, it is a highly endangered species. In this report, we characterize ontogenesis of sporangia and spores that are associated with propagation. A wild population of H. serrata plants is localized in western Hunan province, China and protected by Chinese Government to study its development (e.g. sporangia and spores) and ecology. Both field and microscopic observations were conducted for a few of years. The development of sporangia from their initiation to maturation took nearly 1 year. Microscopic observations showed that the sporangial walls were developed from epidermal cells via initiation, cell division, and maturation. The structure of the mature sporangial wall is composed of one layer of epidermis, two middle layers of cells, and one layer of tapetum. Therefore, the sporangium is the eusporangium type. Spore development is characterized into six stages, initiation from epidermal cell and formation of sporogenous cells, primary sporogenous cell, secondary sporogenous cell, spore mother cell, tetrad, and maturation. The sporangial development of H. serrata belongs to the eusporangium type. The development takes approximately 1 year period from the initiation to the maturation. These data are useful for improving propagation of this medicinal plant in the future.

Laser microsurgery of higher plant cell walls permits patch-clamp access

NASA Technical Reports Server (NTRS)

Henriksen, G. H.; Taylor, A. R.; Brownlee, C.; Assmann, S. M.; Evans, M. L. (Principal Investigator)

1996-01-01

Plasma membranes of guard cells in epidermal peels of Vicia faba and Commelina communis can be made accessible to a patch-clamp pipet by removing a small portion (1-3 micrometers in diameter) of the guard cell wall using a microbeam of ultraviolet light generated by a nitrogen laser. Using this laser microsurgical technique, we have measured channel activity across plasma membranes of V. faba guard cells in both cell-attached and isolated patch configurations. Measurements made in the inside-out patch configuration revealed two distinct K(+)-selective channels. Major advantages of the laser microsurgical technique include the avoidance of enzymatic protoplast isolation, the ability to study cell types that have been difficult to isolate as protoplasts or for which enzymatic isolation protocols result in protoplasts not amenable to patch-clamp studies, the maintenance of positional information in single-channel measurements, reduced disruption of cell-wall-mediated signaling pathways, and the ability to investigate intercellular signaling through studies of cells remaining situated within tissue.

A Ca2+-dependent remodelled actin network directs vesicle trafficking to build wall ingrowth papillae in transfer cells.

PubMed

Zhang, Hui-Ming; Colyvas, Kim; Patrick, John W; Offler, Christina E

2017-10-13

The transport function of transfer cells is conferred by an enlarged plasma membrane area, enriched in nutrient transporters, that is supported on a scaffold of wall ingrowth (WI) papillae. Polarized plumes of elevated cytosolic Ca2+ define loci at which WI papillae form in developing adaxial epidermal transfer cells of Vicia faba cotyledons that are induced to trans-differentiate when the cotyledons are placed on culture medium. We evaluated the hypothesis that vesicle trafficking along a Ca2+-regulated remodelled actin network is the mechanism that underpins this outcome. Polarized to the outer periclinal cytoplasm, a Ca2+-dependent remodelling of long actin bundles into short, thin bundles was found to be essential for assembling WI papillae but not the underlying uniform wall layer. The remodelled actin network directed polarized vesicle trafficking to sites of WI papillae construction, and a pharmacological study indicated that both exo- and endocytosis contributed to assembly of the papillae. Potential candidates responsible for the Ca2+-dependent actin remodelling, along with those underpinning polarized exo- and endocyotosis, were identified in a transcriptome RNAseq database generated from the trans-differentiating epidermal cells. Of most significance, endocytosis was controlled by up-regulated expression of a dynamin-like isoform. How a cycle of localized exo- and endocytosis, regulated by Ca2+-dependent actin remodelling, assembles WI papillae is discussed. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Quantifying hydrostatic pressure in plant cells by using indentation with an atomic force microscope.

PubMed

Beauzamy, Léna; Derr, Julien; Boudaoud, Arezki

2015-05-19

Plant cell growth depends on a delicate balance between an inner drive-the hydrostatic pressure known as turgor-and an outer restraint-the polymeric wall that surrounds a cell. The classical technique to measure turgor in a single cell, the pressure probe, is intrusive and cannot be applied to small cells. In order to overcome these limitations, we developed a method that combines quantification of topography, nanoindentation force measurements, and an interpretation using a published mechanical model for the pointlike loading of thin elastic shells. We used atomic force microscopy to estimate the elastic properties of the cell wall and turgor pressure from a single force-depth curve. We applied this method to onion epidermal peels and quantified the response to changes in osmolality of the bathing solution. Overall our approach is accessible and enables a straightforward estimation of the hydrostatic pressure inside a walled cell. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Histological study of some Echium vulgare, Pulmonaria officinalis and Symphytum officinale populations.

PubMed

Papp, Nóra; Bencsik, Tímea; Németh, Kitti; Gyergyák, Kinga; Sulc, Alexandra; Farkas, Agnes

2011-10-01

Plants living in different ecological habitats can show significant variability in their histological and phytochemical characters. The main histological features of various populations of three medicinal plants from the Boraginaceae family were studied. Stems, petioles and leaves were investigated by light microscopy in vertical and transverse sections. The outline of the epidermal cells, as well as the shape and cell number of trichomes was studied in leaf surface casts. Differences were measured among the populations of Echium vulgare in the width and height of epidermis cells in the stem, petiole and leaf, as well as in the size of palisade cells in the leaves. Among the populations of Pulmonaria officinalis significant differences were found in the length of trichomes and in the slightly or strongly wavy outline of epidermal radial cell walls. Populations of Symphytum officinale showed variance in the height of epidermal cells in leaves and stems, length of palisade cells and number of intercellular spaces in leaves, and the size of the central cavity in the stem. Boraginaceae bristles were found to be longer in plants in windy/shady habitats as opposed to sunny habitats, both in the leaves and stems ofP. officinalis and S. officinale, which might be connected to varying levels of exposure to wind. Longer epidermal cells were detected in the leaves and stems of both E. vulgare and S. officinale plants living in shady habitats, compared with shorter cells in sunny habitats. Leaf mesophyll cells were shorter in shady habitats as opposed to longer cells in sunny habitats, both in E. vulgare and S. officinale. This combination of histological characters may contribute to the plant's adaptation to various amounts of sunshine. The reported data prove the polymorphism of the studied taxa, as well as their ability to adapt to various ecological circumstances.

Differential Growth in Periclinal and Anticlinal Walls during Lobe Formation in Arabidopsis Cotyledon Pavement Cells

PubMed Central

Barton, Deborah A.; Law, Andrew M.K.; Overall, Robyn L.

2015-01-01

Lobe development in the epidermal pavement cells of Arabidopsis thaliana cotyledons and leaves is thought to take place via tip-like growth on the concave side of lobes driven by localized concentrations of actin filaments and associated proteins, with a predicted role for cortical microtubules in establishing the direction of restricted growth at the convex side. We used homologous landmarks fixed to the outer walls of pavement cells and thin-plate spline analysis to demonstrate that lobes form by differential growth of both the anticlinal and periclinal walls. Most lobes formed within the first 24 h of the cotyledons unfurling, during the period of rapid cell expansion. Cortical microtubules adjacent to the periclinal wall were persistently enriched at the convex side of lobes during development where growth was anisotropic and were less concentrated or absent at the concave side where growth was promoted. Alternating microtubule-enriched and microtubule-free zones at the periclinal wall in neighboring cells predicted sites of new lobes. There was no particular arrangement of cortical actin filaments that could predict where lobes would form. However, drug studies demonstrate that both filamentous actin and microtubules are required for lobe formation. PMID:26296967

Site-specific accumulation and dynamic change of flavonoids in Apocyni Veneti Folium.

PubMed

Chen, Cui-Hua; Xu, Hu; Liu, Xun-Hong; Zou, Li-Si; Wang, Mei; Liu, Zi-Xiu; Fu, Xing-Sheng; Zhao, Hui; Yan, Ying

2017-12-01

Site-specific accumulation of flavonoids in Apocyni Veneti Folium was determined by laser scanning confocal microscope (LSCM) and the localization of catechins also was observed via vanillin-HCl staining under the conventional optical microscope. The contents of five flavonoids in Apocyni Veneti Folium from different harvest times and growth parts were measured using HPLC method. LSCM observation showed that flavonoids are accumulated in cuticle of epidermal cells and vessel walls, especially in protoplasts and nucleolus of the collenchyma cells and the epidermal cells. Catechins are localized in the palisade parenchyma cells and vessel walls, particularly in the laticifers found in the phloem. On the basis of the difference of the maximal emission wavelength between quercetin and kaempferol derivatives which have fluorescence behavior by appropriate treatment, kaempferol and its derivatives are localized exclusively in the cuticle. Results showed that the content of astragalin in Apocyni Veneti Folium from different parts revealed the decreasing trend, while hyperin and isoquercitrin were higher in June and July analyzed by HPLC. In summary, the site-specific accumulation of flavonoids in Apocyni Veneti Folium can be determined by LSCM and vanillin-HCl staining. The contents of flavonoids in Apocyni Veneti Folium are correlated with harvest times and growth parts. © 2017 Wiley Periodicals, Inc.

Differential regulation of cellulose orientation at the inner and outer face of epidermal cells in the Arabidopsis hypocotyl.

PubMed

Crowell, Elizabeth Faris; Timpano, Hélène; Desprez, Thierry; Franssen-Verheijen, Tiny; Emons, Anne-Mie; Höfte, Herman; Vernhettes, Samantha

2011-07-01

It is generally believed that cell elongation is regulated by cortical microtubules, which guide the movement of cellulose synthase complexes as they secrete cellulose microfibrils into the periplasmic space. Transversely oriented microtubules are predicted to direct the deposition of a parallel array of microfibrils, thus generating a mechanically anisotropic cell wall that will favor elongation and prevent radial swelling. Thus far, support for this model has been most convincingly demonstrated in filamentous algae. We found that in etiolated Arabidopsis thaliana hypocotyls, microtubules and cellulose synthase trajectories are transversely oriented on the outer surface of the epidermis for only a short period during growth and that anisotropic growth continues after this transverse organization is lost. Our data support previous findings that the outer epidermal wall is polylamellate in structure, with little or no anisotropy. By contrast, we observed perfectly transverse microtubules and microfibrils at the inner face of the epidermis during all stages of cell expansion. Experimental perturbation of cortical microtubule organization preferentially at the inner face led to increased radial swelling. Our study highlights the previously underestimated complexity of cortical microtubule organization in the shoot epidermis and underscores a role for the inner tissues in the regulation of growth anisotropy.

Differential Regulation of Cellulose Orientation at the Inner and Outer Face of Epidermal Cells in the Arabidopsis Hypocotyl[W

PubMed Central

Crowell, Elizabeth Faris; Timpano, Hélène; Desprez, Thierry; Franssen-Verheijen, Tiny; Emons, Anne-Mie; Höfte, Herman; Vernhettes, Samantha

2011-01-01

It is generally believed that cell elongation is regulated by cortical microtubules, which guide the movement of cellulose synthase complexes as they secrete cellulose microfibrils into the periplasmic space. Transversely oriented microtubules are predicted to direct the deposition of a parallel array of microfibrils, thus generating a mechanically anisotropic cell wall that will favor elongation and prevent radial swelling. Thus far, support for this model has been most convincingly demonstrated in filamentous algae. We found that in etiolated Arabidopsis thaliana hypocotyls, microtubules and cellulose synthase trajectories are transversely oriented on the outer surface of the epidermis for only a short period during growth and that anisotropic growth continues after this transverse organization is lost. Our data support previous findings that the outer epidermal wall is polylamellate in structure, with little or no anisotropy. By contrast, we observed perfectly transverse microtubules and microfibrils at the inner face of the epidermis during all stages of cell expansion. Experimental perturbation of cortical microtubule organization preferentially at the inner face led to increased radial swelling. Our study highlights the previously underestimated complexity of cortical microtubule organization in the shoot epidermis and underscores a role for the inner tissues in the regulation of growth anisotropy. PMID:21742992

Spatial organization of cellulose microfibrils and matrix polysaccharides in primary plant cell walls as imaged by multichannel atomic force microscopy.

PubMed

Zhang, Tian; Zheng, Yunzhen; Cosgrove, Daniel J

2016-01-01

We used atomic force microscopy (AFM), complemented with electron microscopy, to characterize the nanoscale and mesoscale structure of the outer (periclinal) cell wall of onion scale epidermis - a model system for relating wall structure to cell wall mechanics. The epidermal wall contains ~100 lamellae, each ~40 nm thick, containing 3.5-nm wide cellulose microfibrils oriented in a common direction within a lamella but varying by ~30 to 90° between adjacent lamellae. The wall thus has a crossed polylamellate, not helicoidal, wall structure. Montages of high-resolution AFM images of the newly deposited wall surface showed that single microfibrils merge into and out of short regions of microfibril bundles, thereby forming a reticulated network. Microfibril direction within a lamella did not change gradually or abruptly across the whole face of the cell, indicating continuity of the lamella across the outer wall. A layer of pectin at the wall surface obscured the underlying cellulose microfibrils when imaged by FESEM, but not by AFM. The AFM thus preferentially detects cellulose microfibrils by probing through the soft matrix in these hydrated walls. AFM-based nanomechanical maps revealed significant heterogeneity in cell wall stiffness and adhesiveness at the nm scale. By color coding and merging these maps, the spatial distribution of soft and rigid matrix polymers could be visualized in the context of the stiffer microfibrils. Without chemical extraction and dehydration, our results provide multiscale structural details of the primary cell wall in its near-native state, with implications for microfibrils motions in different lamellae during uniaxial and biaxial extensions. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

Apple cuticle: the perfect interface

NASA Astrophysics Data System (ADS)

Curry, Eric; Arey, Bruce

2010-06-01

The domestic apple might well be called an 'extreme' fruit. In the arid Northwest United States, the fruit often tolerates surface temperatures ranging from -2 °C in the early spring to 50 °C in the heat of summer, and again to -2 °C during controlled postharvest storage for up to 12 months. During its 18-month existence, the apple maintains a cuticle that is dynamic and environmentally responsive to protect against 1) cellular water loss during desiccation stress and 2) excessive uptake of standing surface moisture. Physiological disorders of the peel such as russeting, cracking, splitting, flecking and lenticel marking, develop as epidermal cells respond to rapid changes in ambient conditions at specific developmental stages during the growing season. Resultant market losses underlie research investigating the nature of apple cuticle growth and development. Ultrastructural analysis of the pro-cuticle using scanning electron microscopy indicates an overlapping network of lipid-based distally-elongating microtubules--produced by and connected to epidermal cells--which co-polymerize to form an organic solvent-insoluble semi-permeable cutin matrix. Microtubule elongation, aggregation, and polymerization function together as long as the fruit continues to enlarge. The nature of lipid transport from the epidermal cells through the cell wall to become part of the cuticular matrix was explored using an FEI Helios NanoLabTM DualBeamTM focused ion beam/scanning electron microscope on chemically- and cryo-fixed peel tissue from mature or freshly harvested apples. Based on microtubule dimensions, regular projections found at the cell/cuticle interface suggest an array of microtubule-like structures associated with the epidermal cell.

α-Xylosidase plays essential roles in xyloglucan remodelling, maintenance of cell wall integrity, and seed germination in Arabidopsis thaliana

PubMed Central

Shigeyama, Takuma; Watanabe, Asuka; Tokuchi, Konatsu; Toh, Shigeo; Sakurai, Naoki; Shibuya, Naoto; Kawakami, Naoto

2016-01-01

Regulation and maintenance of cell wall physical properties are crucial for plant growth and environmental response. In the germination process, hypocotyl cell expansion and endosperm weakening are prerequisites for dicot seeds to complete germination. We have identified the Arabidopsis mutant thermoinhibition-resistant germination 1 (trg1), which has reduced seed dormancy and insensitivity to unfavourable conditions for germination owing to a loss-of-function mutation of TRG1/XYL1, which encodes an α-xylosidase. Compared to those of wild type, the elongating stem of trg1 showed significantly lower viscoelasticity, and the fruit epidermal cells were longitudinally shorter and horizontally enlarged. Actively growing tissues of trg1 over-accumulated free xyloglucan oligosaccharides (XGOs), and the seed cell wall had xyloglucan with a greatly reduced molecular weight. These observations suggest that XGOs reduce xyloglucan size by serving as an acceptor in transglycosylation and eventually enhancing cell wall loosening. TRG1/XYL1 gene expression was abundant in growing wild-type organs and tissues but relatively low in cells at most actively elongating part of the tissues, suggesting that α-xylosidase contributes to maintaining the mechanical integrity of the primary cell wall in the growing and pre-growing tissues. In germinating seeds of trg1, expression of genes encoding specific abscisic acid and gibberellin metabolism enzymes was altered in accordance with the aberrant germination phenotype. Thus, cell wall integrity could affect seed germination not only directly through the physical properties of the cell wall but also indirectly through the regulation of hormone gene expression. PMID:27605715

Limitation of Cell Elongation in Barley (Hordeum vulgare L.) Leaves Through Mechanical and Tissue-Hydraulic Properties.

PubMed

Touati, Mostefa; Knipfer, Thorsten; Visnovitz, Tamás; Kameli, Abdelkrim; Fricke, Wieland

2015-07-01

The aim of the present study was to assess the mechanical and hydraulic limitation of growth in leaf epidermal cells of barley (Hordeum vulgare L.) in response to agents which affect cellular water (mercuric chloride, HgCl(2)) and potassium (cesium chloride, CsCl; tetraethylammonium, TEA) transport, pump activity of plasma membrane H(+)-ATPase and wall acidification (fusicoccin, FC). Cell turgor (P) was measured with the cell pressure probe, and cell osmotic pressure (π) was analyzed through picoliter osmometry of single-cell extracts. A wall extensibility coefficient (M) and tissue hydraulic conductance coefficient (L) were derived using the Lockhart equation. There was a significant positive linear relationship between relative elemental growth rate and P, which fit all treatments, with an overall apparent yield threshold of 0.368 MPa. Differences in growth between treatments could be explained through differences in P. A comparison of L and M showed that growth in all except the FC treatment was co-limited through hydraulic and mechanical properties, though to various extents. This was accompanied by significant (0.17-0.24 MPa) differences in water potential (ΔΨ) between xylem and epidermal cells in the leaf elongation zone. In contrast, FC-treated leaves showed ΔΨ close to zero and a 10-fold increase in L. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

COBRA-LIKE2, a Member of the Glycosylphosphatidylinositol-Anchored COBRA-LIKE Family, Plays a Role in Cellulose Deposition in Arabidopsis Seed Coat Mucilage Secretory Cells1,2[OPEN

PubMed Central

Ben-Tov, Daniela; Abraham, Yael; Stav, Shira; Thompson, Kevin; Loraine, Ann; Elbaum, Rivka; de Souza, Amancio; Pauly, Markus; Kieber, Joseph J.; Harpaz-Saad, Smadar

2015-01-01

Differentiation of the maternally derived seed coat epidermal cells into mucilage secretory cells is a common adaptation in angiosperms. Recent studies identified cellulose as an important component of seed mucilage in various species. Cellulose is deposited as a set of rays that radiate from the seed upon mucilage extrusion, serving to anchor the pectic component of seed mucilage to the seed surface. Using transcriptome data encompassing the course of seed development, we identified COBRA-LIKE2 (COBL2), a member of the glycosylphosphatidylinositol-anchored COBRA-LIKE gene family in Arabidopsis (Arabidopsis thaliana), as coexpressed with other genes involved in cellulose deposition in mucilage secretory cells. Disruption of the COBL2 gene results in substantial reduction in the rays of cellulose present in seed mucilage, along with an increased solubility of the pectic component of the mucilage. Light birefringence demonstrates a substantial decrease in crystalline cellulose deposition into the cellulosic rays of the cobl2 mutants. Moreover, crystalline cellulose deposition into the radial cell walls and the columella appears substantially compromised, as demonstrated by scanning electron microscopy and in situ quantification of light birefringence. Overall, the cobl2 mutants display about 40% reduction in whole-seed crystalline cellulose content compared with the wild type. These data establish that COBL2 plays a role in the deposition of crystalline cellulose into various secondary cell wall structures during seed coat epidermal cell differentiation. PMID:25583925

Skin integrated with perfusable vascular channels on a chip.

PubMed

Mori, Nobuhito; Morimoto, Yuya; Takeuchi, Shoji

2017-02-01

This paper describes a method for fabricating perfusable vascular channels coated with endothelial cells within a cultured skin-equivalent by fixing it to a culture device connected to an external pump and tubes. A histological analysis showed that vascular channels were constructed in the skin-equivalent, which showed a conventional dermal/epidermal morphology, and the endothelial cells formed tight junctions on the vascular channel wall. The barrier function of the skin-equivalent was also confirmed. Cell distribution analysis indicated that the vascular channels supplied nutrition to the skin-equivalent. Moreover, the feasibility of a skin-equivalent containing vascular channels as a model for studying vascular absorption was demonstrated by measuring test molecule permeation from the epidermal layer into the vascular channels. The results suggested that this skin-equivalent can be used for skin-on-a-chip applications including drug development, cosmetics testing, and studying skin biology. Copyright © 2016 Elsevier Ltd. All rights reserved.

Expression of fungal pectin methylesterase in transgenic tobacco leads to alteration in cell wall metabolism and a dwarf phenotype.

PubMed

Hasunuma, Tomohisa; Fukusaki, Ei-ichiro; Kobayashi, Akio

2004-08-05

A transgenic tobacco plant (Nicotiana tabacum L.) expressing a fungal pectin methylesterase (PME; EC 3.1.1.11) gene derived from a black filamentous fungus, Aspergillus niger was created. Fungal PME should have a wider range of adaptability to substrate pectin compared with plant PME. As expected, the proportion of methyl esters in pectin was reduced in the transgenic tobacco. Consequently, the transgenic plant showed short internodes, small leaves and a dwarf phenotype. At a cellular level, the longitudinal lengths of stem epidermal cells were shorter than those of control plants. This is the first report that fungal PME promotes dwarfism in plants. It is worth noting that in the PME-expressing dwarf plant, the expression levels of cell wall metabolism related genes that included endo-1,4-beta-glucanase, cellulose synthase, endo-xyloglucan transferase and expansin gene were decreased. These results suggest that the expression of fungal PME in plants affects the cell wall metabolism.

Differential Growth in Periclinal and Anticlinal Walls during Lobe Formation in Arabidopsis Cotyledon Pavement Cells.

PubMed

Armour, William J; Barton, Deborah A; Law, Andrew M K; Overall, Robyn L

2015-09-01

Lobe development in the epidermal pavement cells of Arabidopsis thaliana cotyledons and leaves is thought to take place via tip-like growth on the concave side of lobes driven by localized concentrations of actin filaments and associated proteins, with a predicted role for cortical microtubules in establishing the direction of restricted growth at the convex side. We used homologous landmarks fixed to the outer walls of pavement cells and thin-plate spline analysis to demonstrate that lobes form by differential growth of both the anticlinal and periclinal walls. Most lobes formed within the first 24 h of the cotyledons unfurling, during the period of rapid cell expansion. Cortical microtubules adjacent to the periclinal wall were persistently enriched at the convex side of lobes during development where growth was anisotropic and were less concentrated or absent at the concave side where growth was promoted. Alternating microtubule-enriched and microtubule-free zones at the periclinal wall in neighboring cells predicted sites of new lobes. There was no particular arrangement of cortical actin filaments that could predict where lobes would form. However, drug studies demonstrate that both filamentous actin and microtubules are required for lobe formation. © 2015 American Society of Plant Biologists. All rights reserved.

Functional characterization of a tomato COBRA-like gene functioning in fruit development and ripening

PubMed Central

2012-01-01

Background Extensive studies have demonstrated that the COBRA gene is critical for biosynthesis of cell wall constituents comprising structural tissues of roots, stalks, leaves and other vegetative organs, however, its role in fruit development and ripening remains largely unknown. Results We identified a tomato gene (SlCOBRA-like) homologous to Arabidopsis COBRA, and determined its role in fleshy fruit biology. The SlCOBRA-like gene is highly expressed in vegetative organs and in early fruit development, but its expression in fruit declines dramatically during ripening stages, implying a primary role in early fruit development. Fruit-specific suppression of SlCOBRA-like resulted in impaired cell wall integrity and up-regulation of genes encoding proteins involved in cell wall degradation during early fruit development. In contrast, fruit-specific overexpression of SlCOBRA-like resulted in increased wall thickness of fruit epidermal cells, more collenchymatous cells beneath the epidermis, elevated levels of cellulose and reduced pectin solubilization in the pericarp cells of red ripe fruits. Moreover, transgenic tomato fruits overexpressing SlCOBRA-like exhibited desirable early development phenotypes including enhanced firmness and a prolonged shelf life. Conclusions Our results suggest that SlCOBRA-like plays an important role in fruit cell wall architecture and provides a potential genetic tool for extending the shelf life of tomato and potentially additional fruits. PMID:23140186

Altered Expression of Genes Implicated in Xylan Biosynthesis Affects Penetration Resistance against Powdery Mildew.

PubMed

Chowdhury, Jamil; Lück, Stefanie; Rajaraman, Jeyaraman; Douchkov, Dimitar; Shirley, Neil J; Schwerdt, Julian G; Schweizer, Patrick; Fincher, Geoffrey B; Burton, Rachel A; Little, Alan

2017-01-01

Heteroxylan has recently been identified as an important component of papillae, which are formed during powdery mildew infection of barley leaves. Deposition of heteroxylan near the sites of attempted fungal penetration in the epidermal cell wall is believed to enhance the physical resistance to the fungal penetration peg and hence to improve pre-invasion resistance. Several glycosyltransferase (GT) families are implicated in the assembly of heteroxylan in the plant cell wall, and are likely to work together in a multi-enzyme complex. Members of key GT families reported to be involved in heteroxylan biosynthesis are up-regulated in the epidermal layer of barley leaves during powdery mildew infection. Modulation of their expression leads to altered susceptibility levels, suggesting that these genes are important for penetration resistance. The highest level of resistance was achieved when a GT43 gene was co-expressed with a GT47 candidate gene, both of which have been predicted to be involved in xylan backbone biosynthesis. Altering the expression level of several candidate heteroxylan synthesis genes can significantly alter disease susceptibility. This is predicted to occur through changes in the amount and structure of heteroxylan in barley papillae.

α-Xylosidase plays essential roles in xyloglucan remodelling, maintenance of cell wall integrity, and seed germination in Arabidopsis thaliana.

PubMed

Shigeyama, Takuma; Watanabe, Asuka; Tokuchi, Konatsu; Toh, Shigeo; Sakurai, Naoki; Shibuya, Naoto; Kawakami, Naoto

2016-10-01

Regulation and maintenance of cell wall physical properties are crucial for plant growth and environmental response. In the germination process, hypocotyl cell expansion and endosperm weakening are prerequisites for dicot seeds to complete germination. We have identified the Arabidopsis mutant thermoinhibition-resistant germination 1 (trg1), which has reduced seed dormancy and insensitivity to unfavourable conditions for germination owing to a loss-of-function mutation of TRG1/XYL1, which encodes an α-xylosidase. Compared to those of wild type, the elongating stem of trg1 showed significantly lower viscoelasticity, and the fruit epidermal cells were longitudinally shorter and horizontally enlarged. Actively growing tissues of trg1 over-accumulated free xyloglucan oligosaccharides (XGOs), and the seed cell wall had xyloglucan with a greatly reduced molecular weight. These observations suggest that XGOs reduce xyloglucan size by serving as an acceptor in transglycosylation and eventually enhancing cell wall loosening. TRG1/XYL1 gene expression was abundant in growing wild-type organs and tissues but relatively low in cells at most actively elongating part of the tissues, suggesting that α-xylosidase contributes to maintaining the mechanical integrity of the primary cell wall in the growing and pre-growing tissues. In germinating seeds of trg1, expression of genes encoding specific abscisic acid and gibberellin metabolism enzymes was altered in accordance with the aberrant germination phenotype. Thus, cell wall integrity could affect seed germination not only directly through the physical properties of the cell wall but also indirectly through the regulation of hormone gene expression. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Differentiation of human endometrial stem cells into urothelial cells on a three-dimensional nanofibrous silk-collagen scaffold: an autologous cell resource for reconstruction of the urinary bladder wall.

PubMed

Shoae-Hassani, Alireza; Mortazavi-Tabatabaei, Seyed Abdolreza; Sharif, Shiva; Seifalian, Alexander Marcus; Azimi, Alireza; Samadikuchaksaraei, Ali; Verdi, Javad

2015-11-01

Reconstruction of the bladder wall via in vitro differentiated stem cells on an appropriate scaffold could be used in such conditions as cancer and neurogenic urinary bladder. This study aimed to examine the potential of human endometrial stem cells (EnSCs) to form urinary bladder epithelial cells (urothelium) on nanofibrous silk-collagen scaffolds, for construction of the urinary bladder wall. After passage 4, EnSCs were induced by keratinocyte growth factor (KGF) and epidermal growth factor (EGF) and seeded on electrospun collagen-V, silk and silk-collagen nanofibres. Later we tested urothelium-specific genes and proteins (uroplakin-Ia, uroplakin-Ib, uroplakin-II, uroplakin-III and cytokeratin 20) by immunocytochemistry, RT-PCR and western blot analyses. Scanning electron microscopy (SEM) and histology were used to detect cell-matrix interactions. DMEM/F12 supplemented by KGF and EGF induced EnSCs to express urothelial cell-specific genes and proteins. Either collagen, silk or silk-collagen scaffolds promoted cell proliferation. The nanofibrous silk-collagen scaffolds provided a three-dimensional (3D) structure to maximize cell-matrix penetration and increase differentiation of the EnSCs. Human EnSCs seeded on 3D nanofibrous silk-collagen scaffolds and differentiated to urothelial cells provide a suitable source for potential use in bladder wall reconstruction in women. Copyright © 2013 John Wiley & Sons, Ltd.

Movement of endogenous calcium in the elongating zone of graviresponding roots of Zea mays

NASA Technical Reports Server (NTRS)

Moore, R.; Cameron, I. L.; Smith, N. K.

1989-01-01

Endogenous calcium (Ca) accumulates along the lower side of the elongating zone of horizontally oriented roots of Zea mays cv. Yellow Dent. This accumulation of Ca correlates positively with the onset of gravicurvature, and occurs in the cytoplasm, cell walls and mucilage of epidermal cells. Corresponding changes in endogenous Ca do not occur in cortical cells of the elongating zone of intact roots. These results indicate that the calcium asymmetries associated with root gravicurvature occur in the outermost layers of the root.

Cellular expansion and gene expression in the developing grape (Vitis vinifera L.).

PubMed

Schlosser, J; Olsson, N; Weis, M; Reid, K; Peng, F; Lund, S; Bowen, P

2008-01-01

Expression profiles of genes involved in cell wall metabolism and water transport were compared with changes in grape (Vitis vinifera L.) berry growth, basic chemical composition, and the shape, size, and wall thickness of cells within tissues of the berry pericarp. Expression of cell wall-modifying and aquaporin genes in berry pericarp tissues generally followed a bimodal expression profile with high levels of expression coinciding with the two periods of rapid berry growth, stages I and III, and low levels of expression corresponding to the slow-growth period, stage II. Cellular expansion was observed throughout all tissues during stage I, and only mesocarp cellular expansion was observed during stage III. Expansion of only exocarp cells was evident during transition between stages II and III. Cell wall-modifying and aquaporin gene expression profiles followed similar trends in exocarp and mesocarp tissues throughout berry development, with the exception of the up-regulation of pectin methylesterase, pectate lyase, two aquaporin genes (AQ1 and AQ2), and two expansin genes (EXP3 and EXPL) during stage II, which was delayed in the exocarp tissue compared with mesocarp tissue. Exocarp endo-(1-->3)-beta-glucanase and expansin-like gene expression was concurrent with increases in epidermal and hypodermal cell wall thickness. These results indicate a potential role of the grape berry skin in modulating grape berry growth.

Changes in apoplastic peroxidase activity and cell wall composition are associated with cold-induced morpho-anatomical plasticity of wheat leaves.

PubMed

Lorenzo, M; Pinedo, M L; Equiza, M A; Fernández, P V; Ciancia, M; Ganem, D G; Tognetti, J A

2018-02-14

Temperate grasses, such as wheat, become compact plants with small thick leaves after exposure to low temperature. These responses are associated with cold hardiness, but their underlying mechanisms remain largely unknown. Here we analyse the effects of low temperature on leaf morpho-anatomical structure, cell wall composition and activity of extracellular peroxidases, which play key roles in cell elongation and cell wall thickening, in two wheat cultivars with contrasting cold-hardening ability. A combined microscopy and biochemical approach was applied to study actively growing leaves of winter (ProINTA-Pincén) and spring (Buck-Patacón) wheat developed under constant warm (25 °C) or cool (5 °C) temperature. Cold-grown plants had shorter leaves but longer inter-stomatal epidermal cells than warm-grown plants. They had thicker walls in metaxylem vessels and mestome sheath cells, paralleled with accumulation of wall components, predominantly hemicellulose. These effects were more pronounced in the winter cultivar (Pincén). Cold also induced a sharp decrease in apoplastic peroxidase activity within the leaf elongating zone of Pincén, and a three-fold increase in the distal mature zone of the leaf. This was consistent with the enhanced cell length and thicker cell walls in this cultivar at 5 °C. The different response to low temperature of apoplastic peroxidase activity and hemicellulose between leaf zones and cultivar types suggests they might play a central role in the development of cold-induced compact morphology and cold hardening. New insights are presented on the potential temperature-driven role of peroxidases and hemicellulose in cell wall dynamics of grasses. © 2018 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.

Reducing cell wall feruloylation by expression of a fungal ferulic acid esterase in Festuca arundinacea modifies plant growth, leaf morphology and the turnover of cell wall arabinoxylans

PubMed Central

Iyer, Prashanti R.; Buanafina, M. Fernanda; Shearer, Erica A.

2017-01-01

A feature of cell wall arabinoxylan in grasses is the presence of ferulic acid which upon oxidative coupling by the action of peroxidases forms diferuloyl bridges between formerly separated arabinoxylans. Ferulate cross-linking is suspected of playing various roles in different plant processes. Here we investigate the role of cell wall feruloyaltion in two major processes, that of leaf growth and the turnover of cell wall arabinoxylans on leaf senescence in tall fescue using plants in which the level of cell wall ferulates has been reduced by targeted expression of the Aspergillus niger ferulic acid esterase A (FAEA) to the apoplast or Golgi. Analysis of FAE expressing plants showed that all the lines had shorter and narrower leaves compared to control, which may be a consequence of the overall growth rate being lower and occurring earlier in FAE expressing leaves than in controls. Furthermore, the final length of epidermal cells was shorter than controls, indicating that their expansion was curtailed earlier than in control leaves. This may be due to the observations that the deposition of both ether and ester linked monomeric hydroxycinnamic acids and ferulate dimerization stopped earlier in FAE expressing leaves but at a lower level than controls, and hydroxycinnamic acid deposition started to slow down when peroxidase levels increased. It would appear therefore that one of the possible mechanisms for controlling overall leaf morphology such as leaf length and width in grasses, where leaf morphology is highly variable between species, may be the timing of hydroxycinnamic acid deposition in the expanding cell walls as they emerge from cell division into the elongation zone, controlled partially by the onset of peroxidase activity in this region. PMID:28934356

MicroFilament Analyzer, an image analysis tool for quantifying fibrillar orientation, reveals changes in microtubule organization during gravitropism.

PubMed

Jacques, Eveline; Buytaert, Jan; Wells, Darren M; Lewandowski, Michal; Bennett, Malcolm J; Dirckx, Joris; Verbelen, Jean-Pierre; Vissenberg, Kris

2013-06-01

Image acquisition is an important step in the study of cytoskeleton organization. As visual interpretations and manual measurements of digital images are prone to errors and require a great amount of time, a freely available software package named MicroFilament Analyzer (MFA) was developed. The goal was to provide a tool that facilitates high-throughput analysis to determine the orientation of filamentous structures on digital images in a more standardized, objective and repeatable way. Here, the rationale and applicability of the program is demonstrated by analyzing the microtubule patterns in epidermal cells of control and gravi-stimulated Arabidopsis thaliana roots. Differential expansion of cells on either side of the root results in downward bending of the root tip. As cell expansion depends on the properties of the cell wall, this may imply a differential orientation of cellulose microfibrils. As cellulose deposition is orchestrated by cortical microtubules, the microtubule patterns were analyzed. The MFA program detects the filamentous structures on the image and identifies the main orientation(s) within individual cells. This revealed four distinguishable microtubule patterns in root epidermal cells. The analysis indicated that gravitropic stimulation and developmental age are both significant factors that determine microtubule orientation. Moreover, the data show that an altered microtubule pattern does not precede differential expansion. Other possible applications are also illustrated, including field emission scanning electron micrographs of cellulose microfibrils in plant cell walls and images of fluorescent actin. © 2013 The Authors The Plant Journal © 2013 John Wiley & Sons Ltd.

COBRA-LIKE2, a member of the glycosylphosphatidylinositol-anchored COBRA-LIKE family, plays a role in cellulose deposition in arabidopsis seed coat mucilage secretory cells.

PubMed

Ben-Tov, Daniela; Abraham, Yael; Stav, Shira; Thompson, Kevin; Loraine, Ann; Elbaum, Rivka; de Souza, Amancio; Pauly, Markus; Kieber, Joseph J; Harpaz-Saad, Smadar

2015-03-01

Differentiation of the maternally derived seed coat epidermal cells into mucilage secretory cells is a common adaptation in angiosperms. Recent studies identified cellulose as an important component of seed mucilage in various species. Cellulose is deposited as a set of rays that radiate from the seed upon mucilage extrusion, serving to anchor the pectic component of seed mucilage to the seed surface. Using transcriptome data encompassing the course of seed development, we identified COBRA-LIKE2 (COBL2), a member of the glycosylphosphatidylinositol-anchored COBRA-LIKE gene family in Arabidopsis (Arabidopsis thaliana), as coexpressed with other genes involved in cellulose deposition in mucilage secretory cells. Disruption of the COBL2 gene results in substantial reduction in the rays of cellulose present in seed mucilage, along with an increased solubility of the pectic component of the mucilage. Light birefringence demonstrates a substantial decrease in crystalline cellulose deposition into the cellulosic rays of the cobl2 mutants. Moreover, crystalline cellulose deposition into the radial cell walls and the columella appears substantially compromised, as demonstrated by scanning electron microscopy and in situ quantification of light birefringence. Overall, the cobl2 mutants display about 40% reduction in whole-seed crystalline cellulose content compared with the wild type. These data establish that COBL2 plays a role in the deposition of crystalline cellulose into various secondary cell wall structures during seed coat epidermal cell differentiation. © 2015 American Society of Plant Biologists. All Rights Reserved.

Solid-State (13)C NMR Delineates the Architectural Design of Biopolymers in Native and Genetically Altered Tomato Fruit Cuticles.

PubMed

Chatterjee, Subhasish; Matas, Antonio J; Isaacson, Tal; Kehlet, Cindie; Rose, Jocelyn K C; Stark, Ruth E

2016-01-11

Plant cuticles on outer fruit and leaf surfaces are natural macromolecular composites of waxes and polyesters that ensure mechanical integrity and mitigate environmental challenges. They also provide renewable raw materials for cosmetics, packaging, and coatings. To delineate the structural framework and flexibility underlying the versatile functions of cutin biopolymers associated with polysaccharide-rich cell-wall matrices, solid-state NMR spectra and spin relaxation times were measured in a tomato fruit model system, including different developmental stages and surface phenotypes. The hydrophilic-hydrophobic balance of the cutin ensures compatibility with the underlying polysaccharide cell walls; the hydroxy fatty acid structures of outer epidermal cutin also support deposition of hydrophobic waxes and aromatic moieties while promoting the formation of cell-wall cross-links that rigidify and strengthen the cuticle composite during fruit development. Fruit cutin-deficient tomato mutants with compromised microbial resistance exhibit less efficient local and collective biopolymer motions, stiffening their cuticular surfaces and increasing their susceptibility to fracture.

Cellulose and pectin localization in roots of mycorrhizalAllium porrum: labelling continuity between host cell wall and interfacial material.

PubMed

Bonfante-Fasolo, P; Vian, B; Perotto, S; Faccio, A; Knox, J P

1990-03-01

Two different types of contacts (or interfaces) exist between the plant host and the fungus during the vesicular-arbuscular mycorrhizal symbiosis, depending on whether the fungus is intercellular or intracellular. In the first case, the walls of the partners are in contact, while in the second case the fungal wall is separated from the host cytoplasm by the invaginated host plasmamembrane and by an interfacial material. In order to verify the origin of the interfacial material, affinity techniques which allow identification in situ of cell-wall components, were used. Cellobiohydrolase (CBH I) that binds to cellulose and a monoclonal antibody (JIM 5) that reacts with pectic components were tested on roots ofAllium porrum L. (leek) colonized byGlomus versiforme (Karst.) Berch. Both probes gave a labelling specific for the host cell wall, but each probe labelled over specific and distinct areas. The CBH I-colloidal gold complex heavily labelled the thick epidermal cell walls, whereas JIM 5 only labelled this area weakly. Labelling of the hypodermis was mostly on intercellular material after treatment with JIM 5 and only on the wall when CBH I was used. Suberin bands found on the radial walls were never labelled. Cortical cells were mostly labelled on the middle lamella with JIM 5 and on the wall with CBH I. Gold granules from the two probes were found in interfacial material both near the point where the fungus enters the cell and around the thin hyphae penetrating deep into the cell. The ultrastructural observations demonstrate that cellulose and pectic components have different but complementary distributions in the walls of root cells involved in the mycorrhizal symbiosis. These components show a similar distribution in the interfacial material laid down around the vesicular-arbuscular mycorrhizal fungus indicating that the interfacial material is of host origin.

Functional analysis of cellulose and xyloglucan in the walls of stomatal guard cells of Arabidopsis thaliana

DOE PAGES

Rui, Yue; Anderson, Charles T.

2016-01-04

Here, stomatal guard cells are pairs of specialized epidermal cells that control water and CO 2 exchange between the plant and the environment. To fulfill the functions of stomatal opening and closure that are driven by changes in turgor pressure, guard cell walls must be both strong and flexible, but how the structure and dynamics of guard cell walls enable stomatal function remains poorly understood. To address this question, we applied cell biological and genetic analyses to investigate guard cell walls and their relationship to stomatal function in Arabidopsis ( Arabidopsis thaliana). Using live-cell spinning disk confocal microscopy, we measuredmore » the motility of cellulose synthase (CESA)-containing complexes labeled by green fluorescent protein (GFP)-CESA3 and observed a reduced proportion of GFP-CESA3 particles colocalizing with microtubules upon stomatal closure. Imaging cellulose organization in guard cells revealed a relatively uniform distribution of cellulose in the open state and a more fibrillar pattern in the closed state, indicating that cellulose microfibrils undergo dynamic reorganization during stomatal movements. In cesa3 je5 mutants defective in cellulose synthesis and xxt1 xxt2 mutants lacking the hemicellulose xyloglucan, stomatal apertures, changes in guard cell length, and cellulose reorganization were aberrant during fusicoccin-induced stomatal opening or abscisic acid-induced stomatal closure, indicating that sufficient cellulose and xyloglucan are required for normal guard cell dynamics. Together, these results provide new insights into how guard cell walls allow stomata to function as responsive mediators of gas exchange at the plant surface.« less

Functional Analysis of Cellulose and Xyloglucan in the Walls of Stomatal Guard Cells of Arabidopsis1[OPEN

PubMed Central

Rui, Yue; Anderson, Charles T.

2016-01-01

Stomatal guard cells are pairs of specialized epidermal cells that control water and CO2 exchange between the plant and the environment. To fulfill the functions of stomatal opening and closure that are driven by changes in turgor pressure, guard cell walls must be both strong and flexible, but how the structure and dynamics of guard cell walls enable stomatal function remains poorly understood. To address this question, we applied cell biological and genetic analyses to investigate guard cell walls and their relationship to stomatal function in Arabidopsis (Arabidopsis thaliana). Using live-cell spinning disk confocal microscopy, we measured the motility of cellulose synthase (CESA)-containing complexes labeled by green fluorescent protein (GFP)-CESA3 and observed a reduced proportion of GFP-CESA3 particles colocalizing with microtubules upon stomatal closure. Imaging cellulose organization in guard cells revealed a relatively uniform distribution of cellulose in the open state and a more fibrillar pattern in the closed state, indicating that cellulose microfibrils undergo dynamic reorganization during stomatal movements. In cesa3je5 mutants defective in cellulose synthesis and xxt1 xxt2 mutants lacking the hemicellulose xyloglucan, stomatal apertures, changes in guard cell length, and cellulose reorganization were aberrant during fusicoccin-induced stomatal opening or abscisic acid-induced stomatal closure, indicating that sufficient cellulose and xyloglucan are required for normal guard cell dynamics. Together, these results provide new insights into how guard cell walls allow stomata to function as responsive mediators of gas exchange at the plant surface. PMID:26729799

Model system for plant cell biology: GFP imaging in living onion epidermal cells

NASA Technical Reports Server (NTRS)

Scott, A.; Wyatt, S.; Tsou, P. L.; Robertson, D.; Allen, N. S.

1999-01-01

The ability to visualize organelle localization and dynamics is very useful in studying cellular physiological events. Until recently, this has been accomplished using a variety of staining methods. However, staining can give inaccurate information due to nonspecific staining, diffusion of the stain or through toxic effects. The ability to target green fluorescent protein (GFP) to various organelles allows for specific labeling of organelles in vivo. The disadvantages of GFP thus far have been the time and money involved in developing stable transformants or maintaining cell cultures for transient expression. In this paper, we present a rapid transient expression system using onion epidermal peels. We have localized GFP to various cellular compartments (including the cell wall) to illustrate the utility of this method and to visualize dynamics of these compartments. The onion epidermis has large, living, transparent cells in a monolayer, making them ideal for visualizing GFP. This method is easy and inexpensive, and it allows for testing of new GFP fusion proteins in a living tissue to determine deleterious effects and the ability to express before stable transformants are attempted.

The Functions of Grainy Head-Like Proteins in Animals and Fungi and the Evolution of Apical Extracellular Barriers

PubMed Central

Paré, Adam; Kim, Myungjin; Juarez, Michelle T.; Brody, Stuart; McGinnis, William

2012-01-01

The Grainy head (GRH) family of transcription factors are crucial for the development and repair of epidermal barriers in all animals in which they have been studied. This is a high-level functional conservation, as the known structural and enzymatic genes regulated by GRH proteins differ between species depending on the type of epidermal barrier being formed. Interestingly, members of the CP2 superfamily of transcription factors, which encompasses the GRH and LSF families in animals, are also found in fungi – organisms that lack epidermal tissues. To shed light on CP2 protein function in fungi, we characterized a Neurospora crassa mutant lacking the CP2 member we refer to as grainy head-like (grhl). We show that Neurospora GRHL has a DNA-binding specificity similar to that of animal GRH proteins and dissimilar to that of animal LSF proteins. Neurospora grhl mutants are defective in conidial-spore dispersal due to an inability to remodel the cell wall, and we show that grhl mutants and the long-known conidial separation-2 (csp-2) mutants are allelic. We then characterized the transcriptomes of both Neurospora grhl mutants and Drosophila grh mutant embryos to look for similarities in the affected genes. Neurospora grhl appears to play a role in the development and remodeling of the cell wall, as well as in the activation of genes involved in defense and virulence. Drosophila GRH is required to activate the expression of many genes involved in cuticular/epidermal-barrier formation. We also present evidence that GRH plays a role in adult antimicrobial defense. These results, along with previous studies of animal GRH proteins, suggest the fascinating possibility that the apical extracellular barriers of some animals and fungi might share an evolutionary connection, and that the formation of physical barriers in the last common ancestor was under the control of a transcriptional code that included GRH-like proteins. PMID:22590528

Arabinogalactan Proteins Accumulate in the Cell Walls of Searching Hyphae of the Stem Parasitic Plants, Cuscuta campestris and Cuscuta japonica.

PubMed

Hozumi, Akitaka; Bera, Subhankar; Fujiwara, Daiki; Obayashi, Takeshi; Yokoyama, Ryusuke; Nishitani, Kazuhiko; Aoki, Koh

2017-11-01

Stem parasitic plants (Cuscuta spp.) develop a specialized organ called a haustorium to penetrate their hosts' stem tissues. To reach the vascular tissues of the host plant, the haustorium needs to overcome the physical barrier of the cell wall, and the parasite-host interaction via the cell wall is a critical process. However, the cell wall components responsible for the establishment of parasitic connections have not yet been identified. In this study, we investigated the spatial distribution patterns of cell wall components at a parasitic interface using parasite-host complexes of Cuscuta campestris-Arabidopsis thaliana and Cuscuta japonica-Glycine max. We focused on arabinogalactan proteins (AGPs), because AGPs accumulate in the cell walls of searching hyphae of both C. campestris and C. japonica. We found more AGPs in elongated haustoria than in pre haustoria, indicating that AGP accumulation is developmentally regulated. Using in situ hybridization, we identified five genes in C. campestris that encode hyphal-expressed AGPs that belong to the fasciclin-like AGP (FLA) family, which were named CcFLA genes. Three of the five CcFLA genes were expressed in the holdfast, which develops on the Cuscuta stem epidermis at the attachment site for the host's stem epidermis. Our results suggest that AGPs are involved in hyphal elongation and adhesion to host cells, and in the adhesion between the epidermal tissues of Cuscuta and its host. © The Author 2017. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Evaluation of morpho-anatomical and chemical differences between varieties of the medicinal plant Casearia sylvestris Swartz.

PubMed

Claudino, Josiane C; Sacramento, Luis V S do; Koch, Ingrid; Santos, Helen A; Cavalheiro, Alberto J; Tininis, Aristeu G; Santos, André G dos

2013-01-01

Casearia sylvestris Swartz (Salicaceae) has been used in traditional medicine and its leaf extracts have been exhibited important pharmacological activities. The species presents morphological, chemical and genetic variation. Two varieties are considered due external morphological differences: C. sylvestris var. sylvestris and var. lingua. There are difficulties in definition of these varieties. The objective of this work is to evaluate chemical and morpho-anatomical differences between C. sylvestris varieties that can be applied in their distinction for pharmaceutical or botanical purposes. Transverse and paradermic sections of leaves were prepared for morpho-anatomical, histochemical and quantitative microscopy (stomatal and palisade index) analyses. Diterpene profiles of the specimens were obtained by HPLC-DAD and TLC. Morpho-anatomical analyses demonstrated significant differences between the varieties only in paradermic sections: var. sylvestris--polygonal epidermic cell walls and hypostomatic; var. lingua--rounded epidermic cell walls and amphistomatic. No differences were observed for stomatal index; palisade index was found 2.8 for var. lingua and 3.9 for var. sylvestris. Chromatographic analyses confirmed previous results demonstrating that diterpene profile in varieties differs, with predominance of these metabolites in var. sylvestris. In conclusion, this work indicates that chromatographic analysis besides morpho-anatomical analysis can be applied in distinction of C. sylvestris varieties.

On the role of stress anisotropy in the growth of stems.

PubMed

Baskin, Tobias I; Jensen, Oliver E

2013-11-01

We review the role of anisotropic stress in controlling the growth anisotropy of stems. Instead of stress, growth anisotropy is usually considered in terms of compliance. Anisotropic compliance is typical of cell walls, because they contain aligned cellulose microfibrils, and it appears to be sufficient to explain the growth anisotropy of an isolated cell. Nevertheless, a role for anisotropic stress in the growth of stems is indicated by certain growth responses that appear too rapid to be accounted for by changes in cell-wall compliance and because the outer epidermal wall of most growing stems has microfibrils aligned axially, an arrangement that would favour radial expansion based on cell-wall compliance alone. Efforts to quantify stress anisotropy in the stem have found that it is predominantly axial, and large enough in principle to explain the elongation of the epidermis, despite its axial microfibrils. That the epidermis experiences a stress deriving from the inner tissue, the so-called 'tissue stress', has been widely recognized; however, the origin of the dominant axial direction remains obscure. Based on geometry, an isolated cylindrical cell should have an intramural stress anisotropy favouring the transverse direction. Explanations for tissue stress have invoked differential elastic moduli, differential plastic deformation (so-called differential growth), and a phenomenon analogous to the maturation stress generated by secondary cell walls. None of these explanations has been validated. We suggest that understanding the role of stress anisotropy in plant growth requires a deeper understanding of the nature of stress in hierarchical, organic structures.

Onion epidermis as a new model to study the control of growth anisotropy in higher plants.

PubMed

Suslov, Dmitry; Verbelen, Jean-Pierre; Vissenberg, Kris

2009-01-01

To elucidate the role of cellulose microfibrils in the control of growth anisotropy, a link between their net orientation, in vitro cell wall extensibility, and anisotropic cell expansion was studied during development of the adaxial epidermis of onion (Allium cepa) bulb scales using polarization confocal microscopy, creep tests, and light microscopy. During growth the net cellulose alignment across the whole thickness of the outer epidermal wall changed from transverse through random to longitudinal and back to transverse relative to the bulb axis. Cell wall extension in vitro was always higher transverse than parallel to the net cellulose alignment. The direction of growth anisotropy was perpendicular to the net microfibril orientation and changed during development from longitudinal to transverse to the bulb axis. The correlation between the degree of growth anisotropy and the net cellulose alignment was poor. Thus the net cellulose microfibril orientation across the whole thickness of the outer periclinal epidermis wall defines the direction but not the degree of growth anisotropy. Strips isolated from the epidermis in the directions perpendicular and transverse to a net cellulose orientation can be used as an extensiometric model to prove a protein involvement in the control of growth anisotropy.

Could the Extended Phenotype Extend to the Cellular and Subcellular Levels in Insect-Induced Galls?

PubMed Central

Carneiro, Renê Gonçalves da Silva; Pacheco, Priscilla; Isaias, Rosy Mary dos Santos

2015-01-01

Neo-ontogenesis of plant galls involves redifferentiation of host plant tissues to express new phenotypes, when new cell properties are established via structural-functional remodeling. Herein, Psidium cattleianum leaves and Nothotrioza cattleiani galls are analyzed by developmental anatomy, cytometry and immunocytochemistry of cell walls. We address hypothesis-driven questions concerning the organogenesis of globoid galls in the association of P. cattleianum - N. cattleianum, and P. myrtoides - N. myrtoidis. These double co-generic systems represent good models for comparing final gall shapes and cell lineages functionalities under the perspective of convergent plant-dependent or divergent insect-induced characteristics. Gall induction, and growth and development are similar in both galls, but homologous cell lineages exhibit divergent degrees of cell hypertrophy and directions of elongation. Median cortical cells in P. cattleianum galls hypertrophy the most, while in P. myrtoides galls there is a centrifugal gradient of cell hypertrophy. Cortical cells in P. cattleianum galls tend to anisotropy, while P. myrtoidis galls have isotropically hypertrophied cells. Immunocytochemistry evidences the chemical identity and functional traits of cell lineages: epidermal cells walls have homogalacturonans (HGAs) and galactans, which confer rigidity to sites of enhanced cell division; oil gland cell walls have arabinogalactan proteins (AGPs) that help avoiding cell death; and parenchyma cell walls have HGAs, galactans and arabinans, which confer porosity. Variations in such chemical identities are related to specific sites of hypertrophy. Even though the double co-generic models have the same macroscopic phenotype, the globoid morphotype, current analyses indicate that the extended phenotype of N. cattleiani is substantiated by cellular and subcellular specificities. PMID:26053863

Precooling and ozone treatments affects postharvest quality of black mulberry (Morus nigra) fruits.

PubMed

Han, Qiang; Gao, Haiyan; Chen, Hangjun; Fang, Xiangjun; Wu, Weijie

2017-04-15

Mulberry (Morus spp.) fruits are delicious and nutritious, but they are highly perishable and have a very short shelf-life for sale in the market. This study investigated the effect and mechanisms of 2ppm ozone and precooling treatments on the postharvest quality of mulberry fruit during refrigerated storage. The results revealed that mulberry fruit subjected to ozone and precooling treatment had higher levels of titratable acidity and total soluble solids content, better retention in firmness and color, and lower decay rate, respiratory intensity, and polyphenol oxidase activity compared to the control. From the analysis of cell ultrastructure and cell wall components of fruit, ozone and precooling treatments also induced shrinkage of the stomata in the epidermis, inhibited bacteria invasion, reduced water transpiration, and delayed the decomposition of the cell walls and the degradation of epidermal tissues. Copyright © 2016. Published by Elsevier Ltd.

(Hydroxyproline-rich glycoprotein of the plant cell wall): Report on work from June 1987 to June 1988

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1988-01-01

In soybean seed costs the accumulation of the hydroxproline-rich glycoprotein extensin is regulated in a developmental and tissue-specific manner. The time course of appearance of extensin during seed development was studied by Western blot analysis and by immunogold-silver localization. Using these techniques extensin was first detected at 16 to 18 d after anthesis, increasing during development to high levels at 24 d after anthesis. Immunogold-silver localization of extensin in the seed coat showed marked depostion of the glycoprotein in the walls of palisade epidermal cells and hourglass cells. The immunolocalization of extensin in developing soybean seeds was also made bymore » a new technique - tissue printing on nitrocellulose paper. This technique shows that extensin is primarily localized in the seed coal, hilum, and vascular elements of the seed.« less

A Versatile Click-Compatible Monolignol Probe to Study Lignin Deposition in Plant Cell Walls

PubMed Central

Pandey, Jyotsna L.; Wang, Bo; Diehl, Brett G.; Richard, Tom L.; Chen, Gong; Anderson, Charles T.

2015-01-01

Lignin plays important structural and functional roles in plants by forming a hydrophobic matrix in secondary cell walls that enhances mechanical strength and resists microbial decay. While the importance of the lignin matrix is well documented and the biosynthetic pathways for monolignols are known, the process by which lignin precursors or monolignols are transported and polymerized to form this matrix remains a subject of considerable debate. In this study, we have synthesized and tested an analog of coniferyl alcohol that has been modified to contain an ethynyl group at the C-3 position. This modification enables fluorescent tagging and imaging of this molecule after its incorporation into plant tissue by click chemistry-assisted covalent labeling with a fluorescent azide dye, and confers a distinct Raman signature that could be used for Raman imaging. We found that this monolignol analog is incorporated into in vitro-polymerized dehydrogenation polymer (DHP) lignin and into root epidermal cell walls of 4-day-old Arabidopsis seedlings. Incorporation of the analog in stem sections of 6-week-old Arabidopsis thaliana plants and labeling with an Alexa-594 azide dye revealed the precise locations of new lignin polymerization. Results from this study indicate that this molecule can provide high-resolution localization of lignification during plant cell wall maturation and lignin matrix assembly. PMID:25884205

Developmental patterning of sub-epidermal cells in the outer integument of Arabidopsis seeds

PubMed Central

Fiume, Elisa; Coen, Olivier; Xu, Wenjia; Lepiniec, Loïc

2017-01-01

The seed, the reproductive unit of angiosperms, is generally protected by the seed coat. The seed coat is made of one or two integuments, each comprising two epidermal cells layers and, in some cases, extra sub-epidermal cell layers. The thickness of the seed-coat affects several aspects of seed biology such as dormancy, germination and mortality. In Arabidopsis, the inner integument displays one or two sub-epidermal cell layers that originate from periclinal cell divisions of the innermost epidermal cell layer. By contrast, the outer integument was considered to be two-cell layered. Here, we show that sub-epidermal chalazal cells grow in between the epidermal outer integument cell layers to create an incomplete three-cell layered outer integument. We found that the MADS box transcription factor TRANSPARENT TESTA 16 represses growth of the chalaza and formation of sub-epidermal outer integument cells. Finally, we demonstrate that sub-epidermal cells of the outer and inner integument respond differently to the repressive mechanism mediated by FERTILIZATION INDEPENDENT SEED Polycomb group proteins and to fertilization signals. Our data suggest that integument cell origin rather than sub-epidermal cell position underlies different responses to fertilization. PMID:29141031

Resistant tissues of modern marchantioid liverworts resemble enigmatic Early Paleozoic microfossils

PubMed Central

Graham, Linda E.; Wilcox, Lee W.; Cook, Martha E.; Gensel, Patricia G.

2004-01-01

Absence of a substantial pretracheophyte fossil record for bryophytes (otherwise predicted by molecular systematics) poses a major problem in our understanding of earliest land-plant structure. In contrast, there exist enigmatic Cambrian–Devonian microfossils (aggregations of tubes or sheets of cells or possibly a combination of both) controversially interpreted as an extinct group of early land plants known as nematophytes. We used an innovative approach to explore these issues: comparison of tube and cell-sheet microfossils with experimentally degraded modern liverworts as analogues of ancient early land plants. Lower epidermal surface tissues, including rhizoids, of Marchantia polymorpha and Conocephalum conicum were resistant to breakdown after rotting for extended periods or high-temperature acid treatment (acetolysis), suggesting fossilization potential. Cell-sheet and rhizoid remains occurred separately or together depending on the degree of body degradation. Rhizoid break-off at the lower epidermal surface left rimmed pores at the centers of cell rosettes; these were similar in structure, diameter, and distribution to pores characterizing nematophyte cell-sheet microfossils known as Cosmochlaina. The range of Marchantia rhizoid diameters overlapped that of Cosmochlaina pores. Approximately 14% of dry biomass of Marchantia vegetative thalli and 40% of gametangiophores was resistant to acetolysis. Pre- and posttreatment cell-wall autofluorescence suggested the presence of phenolic compounds that likely protect lower epidermal tissues from soil microbe attack and provide dimensional stability to gametangiophores. Our results suggest that at least some microfossils identified as nematophytes may be the remains of early marchantioid liverworts similar in some ways to modern Marchantia and Conocephalum. PMID:15263095

HIGHLY METHYL ESTERIFIED SEEDS is a pectin methyl esterase involved in embryo development.

PubMed

Levesque-Tremblay, Gabriel; Müller, Kerstin; Mansfield, Shawn D; Haughn, George W

2015-03-01

Homogalacturonan pectin domains are synthesized in a highly methyl-esterified form that later can be differentially demethyl esterified by pectin methyl esterase (PME) to strengthen or loosen plant cell walls that contain pectin, including seed coat mucilage, a specialized secondary cell wall of seed coat epidermal cells. As a means to identify the active PMEs in seed coat mucilage, we identified seven PMEs expressed during seed coat development. One of these, HIGHLY METHYL ESTERIFIED SEEDS (HMS), is abundant during mucilage secretion, peaking at 7 d postanthesis in both the seed coat and the embryo. We have determined that this gene is required for normal levels of PME activity and homogalacturonan methyl esterification in the seed. The hms-1 mutant displays altered embryo morphology and mucilage extrusion, both of which are a consequence of defects in embryo development. A significant decrease in the size of cells in the embryo suggests that the changes in embryo morphology are a consequence of lack of cell expansion. Progeny from a cross between hms-1 and the previously characterized PME inhibitor5 overexpression line suggest that HMS acts independently from other cell wall-modifying enzymes in the embryo. We propose that HMS is required for cell wall loosening in the embryo to facilitate cell expansion during the accumulation of storage reserves and that its role in the seed coat is masked by redundancy. © 2015 American Society of Plant Biologists. All Rights Reserved.

Epidermal stem cells: location, potential and contribution to cancer.

PubMed

Ambler, C A; Määttä, A

2009-01-01

Epidermal stem cells have been classically characterized as slow-cycling, long-lived cells that reside in discrete niches in the skin. Gene expression studies of niche-resident cells have revealed a number of stem cell markers and regulators, including the Wnt/beta-catenin, Notch, p63, c-Myc and Hedgehog pathways. A new study challenges the traditional developmental paradigm of slow-cycling stem cells and rapid-cycling transit amplifying cells in some epidermal regions, and there is mounting evidence to suggest that multi-lineage epidermal progenitors can be isolated from highly proliferative, non-niche regions. Whether there is a unique microenvironment surrounding these progenitors remains to be determined. Interestingly, cancer stem cells derived from epidermal tumours exist independent of the classic skin stem cell niche, yet also have stem cell properties, including multi-lineage differentiation. This review summarizes recent studies identifying the location and regulators of mouse and human epidermal stem cells and highlights the strategies used to identify cancer stem cells, including expression of normal epidermal stem cell markers, expression of cancer stem cell markers identified in other epidermal tumours and characterization of side-population tumour cells.

The Arabidopsis SOS5 Locus Encodes a Putative Cell Surface Adhesion Protein and Is Required for Normal Cell Expansion

PubMed Central

Shi, Huazhong; Kim, YongSig; Guo, Yan; Stevenson, Becky; Zhu, Jian-Kang

2003-01-01

Cell surface proteoglycans have been implicated in many aspects of plant growth and development, but genetic evidence supporting their function has been lacking. Here, we report that the Salt Overly Sensitive5 (SOS5) gene encodes a putative cell surface adhesion protein and is required for normal cell expansion. The sos5 mutant was isolated in a screen for Arabidopsis salt-hypersensitive mutants. Under salt stress, the root tips of sos5 mutant plants swell and root growth is arrested. The root-swelling phenotype is caused by abnormal expansion of epidermal, cortical, and endodermal cells. The SOS5 gene was isolated through map-based cloning. The predicted SOS5 protein contains an N-terminal signal sequence for plasma membrane localization, two arabinogalactan protein–like domains, two fasciclin-like domains, and a C-terminal glycosylphosphatidylinositol lipid anchor signal sequence. The presence of fasciclin-like domains, which typically are found in animal cell adhesion proteins, suggests a role for SOS5 in cell-to-cell adhesion in plants. The SOS5 protein was present at the outer surface of the plasma membrane. The cell walls are thinner in the sos5 mutant, and those between neighboring epidermal and cortical cells in sos5 roots appear less organized. SOS5 is expressed ubiquitously in all plant organs and tissues, including guard cells in the leaf. PMID:12509519

[Progress in epidermal stem cells].

PubMed

Wang, Li-Juan; Wang, You-Liang; Yang, Xiao

2010-03-01

Mammalian skin epidermis contains different epidermal stem cell pools which contribute to the homeostasis and repair of skin epithelium. Epidermal stem cells possess two essential features common to all stem cells: self-renewal and differentiation. Disturbing the balance between self-renewal and differentiation of epidermal stem cell often causes tumors or other skin diseases. Epidermal stem cell niches provide a special microenvironment that maintains a balance of stem cell quiescence and activity. This review primarily concentrates on the following points of the epidermal stem cells: the existing evidences, the self-renewal and differentiation, the division pattern, the signal pathways regulating self-renewal and differentiation, and the microenvironment (niche) and macroenvironment maintaining the homeostasis of stem cells.

Identification among morphologically similar Argyreia (Convolvulaceae) based on leaf anatomy and phenetic analyses.

PubMed

Traiperm, Paweena; Chow, Janene; Nopun, Possathorn; Staples, G; Swangpol, Sasivimon C

2017-12-01

The genus Argyreia Lour. is one of the species-rich Asian genera in the family Convolvulaceae. Several species complexes were recognized in which taxon delimitation was imprecise, especially when examining herbarium materials without fully developed open flowers. The main goal of this study is to investigate and describe leaf anatomy for some morphologically similar Argyreia using epidermal peeling, leaf and petiole transverse sections, and scanning electron microscopy. Phenetic analyses including cluster analysis and principal component analysis were used to investigate the similarity of these morpho-types. Anatomical differences observed between the morpho-types include epidermal cell walls and the trichome types on the leaf epidermis. Additional differences in the leaf and petiole transverse sections include the epidermal cell shape of the adaxial leaf blade, the leaf margins, and the petiole transverse sectional outline. The phenogram from cluster analysis using the UPGMA method represented four groups with an R value of 0.87. Moreover, the important quantitative and qualitative leaf anatomical traits of the four groups were confirmed by the principal component analysis of the first two components. The results from phenetic analyses confirmed the anatomical differentiation between the morpho-types. Leaf anatomical features regarded as particularly informative for morpho-type differentiation can be used to supplement macro morphological identification.

Self-assembled polyhydroxy fatty acids vesicles: a mechanism for plant cutin synthesis.

PubMed

Heredia-Guerrero, José A; Benítez, José J; Heredia, Antonio

2008-03-01

Despite its biological importance, the mechanism of formation of cutin, the polymeric matrix of plant cuticles, has not yet been fully clarified. Here, for the first time, we show the participation in the process of lipid vesicles formed by the self-assembly of endogenous polyhydroxy fatty acids. The accumulation and fusion of these vesicles (cutinsomes) at the outer part of epidermal cell wall is proposed as the mechanism for early cuticle formation.

Cell Wall Architecture of the Elongating Maize Coleoptile1

PubMed Central

Carpita, Nicholas C.; Defernez, Marianne; Findlay, Kim; Wells, Brian; Shoue, Douglas A.; Catchpole, Gareth; Wilson, Reginald H.; McCann, Maureen C.

2001-01-01

The primary walls of grasses are composed of cellulose microfibrils, glucuronoarabinoxylans (GAXs), and mixed-linkage β-glucans, together with smaller amounts of xyloglucans, glucomannans, pectins, and a network of polyphenolic substances. Chemical imaging by Fourier transform infrared microspectroscopy revealed large differences in the distributions of many chemical species between different tissues of the maize (Zea mays) coleoptile. This was confirmed by chemical analyses of isolated outer epidermal tissues compared with mesophyll-enriched preparations. Glucomannans and esterified uronic acids were more abundant in the epidermis, whereas β-glucans were more abundant in the mesophyll cells. The localization of β-glucan was confirmed by immunocytochemistry in the electron microscope and quantitative biochemical assays. We used field emission scanning electron microscopy, infrared microspectroscopy, and biochemical characterization of sequentially extracted polymers to further characterize the cell wall architecture of the epidermis. Oxidation of the phenolic network followed by dilute NaOH extraction widened the pores of the wall substantially and permitted observation by scanning electron microscopy of up to six distinct microfibrillar lamellae. Sequential chemical extraction of specific polysaccharides together with enzymic digestion of β-glucans allowed us to distinguish two distinct domains in the grass primary wall. First, a β-glucan-enriched domain, coextensive with GAXs of low degrees of arabinosyl substitution and glucomannans, is tightly associated around microfibrils. Second, a GAX that is more highly substituted with arabinosyl residues and additional glucomannan provides an interstitial domain that interconnects the β-glucan-coated microfibrils. Implications for current models that attempt to explain the biochemical and biophysical mechanism of wall loosening during cell growth are discussed. PMID:11598229

The development and geometry of shape change in Arabidopsis thaliana cotyledon pavement cells

PubMed Central

2011-01-01

Background The leaf epidermis is an important architectural control element that influences the growth properties of underlying tissues and the overall form of the organ. In dicots, interdigitated pavement cells are the building blocks of the tissue, and their morphogenesis includes the assembly of specialized cell walls that surround the apical, basal, and lateral (anticlinal) cell surfaces. The microtubule and actin cytoskeletons are highly polarized along the cortex of the anticlinal wall; however, the relationships between these arrays and cell morphogenesis are unclear. Results We developed new quantitative tools to compare population-level growth statistics with time-lapse imaging of cotyledon pavement cells in an intact tissue. The analysis revealed alternating waves of lobe initiation and a phase of lateral isotropic expansion that persisted for days. During lateral isotropic diffuse growth, microtubule organization varied greatly between cell surfaces. Parallel microtubule bundles were distributed unevenly along the anticlinal surface, with subsets marking stable cortical domains at cell indentations and others clearly populating the cortex within convex cell protrusions. Conclusions Pavement cell morphogenesis is discontinuous, and includes punctuated phases of lobe initiation and lateral isotropic expansion. In the epidermis, lateral isotropic growth is independent of pavement cell size and shape. Cortical microtubules along the upper cell surface and stable cortical patches of anticlinal microtubules may coordinate the growth behaviors of orthogonal cell walls. This work illustrates the importance of directly linking protein localization data to the growth behavior of leaf epidermal cells. PMID:21284861

The development and geometry of shape change in Arabidopsis thaliana cotyledon pavement cells.

PubMed

Zhang, Chunhua; Halsey, Leah E; Szymanski, Daniel B

2011-02-01

The leaf epidermis is an important architectural control element that influences the growth properties of underlying tissues and the overall form of the organ. In dicots, interdigitated pavement cells are the building blocks of the tissue, and their morphogenesis includes the assembly of specialized cell walls that surround the apical, basal, and lateral (anticlinal) cell surfaces. The microtubule and actin cytoskeletons are highly polarized along the cortex of the anticlinal wall; however, the relationships between these arrays and cell morphogenesis are unclear. We developed new quantitative tools to compare population-level growth statistics with time-lapse imaging of cotyledon pavement cells in an intact tissue. The analysis revealed alternating waves of lobe initiation and a phase of lateral isotropic expansion that persisted for days. During lateral isotropic diffuse growth, microtubule organization varied greatly between cell surfaces. Parallel microtubule bundles were distributed unevenly along the anticlinal surface, with subsets marking stable cortical domains at cell indentations and others clearly populating the cortex within convex cell protrusions. Pavement cell morphogenesis is discontinuous, and includes punctuated phases of lobe initiation and lateral isotropic expansion. In the epidermis, lateral isotropic growth is independent of pavement cell size and shape. Cortical microtubules along the upper cell surface and stable cortical patches of anticlinal microtubules may coordinate the growth behaviors of orthogonal cell walls. This work illustrates the importance of directly linking protein localization data to the growth behavior of leaf epidermal cells.

Functional Analysis of the p40 and p75 Proteins from Lactobacillus casei BL23

PubMed Central

Bäuerl, Christine; Pérez-Martínez, Gaspar; Yan, Fang; Polk, D. Brent; Monedero, Vicente

2011-01-01

The genomes of Lactobacillus casei/paracasei and Lactobacillus rhamnosus strains carry two genes encoding homologues of p40 and p75 from L. rhamnosus GG, two secreted proteins which display anti-apoptotic and cell protective effects on human intestinal epithelial cells. p40 and p75 carry cysteine, histidine-dependent aminohydrolase/peptidase (CHAP) and NLPC/P60 domains, respectively, which are characteristic of proteins with cell-wall hydrolase activity. In L. casei BL23 both proteins were secreted to the growth medium and were also located at the bacterial cell surface. The genes coding for both proteins were inactivated in this strain. Inactivation of LCABL_00230 (encoding p40) did not result in a significant difference in phenotype, whereas a mutation in LCABL_02770 (encoding p75) produced cells that formed very long chains. Purified glutathione-S-transferase (GST)-p40 and -p75 fusion proteins were able to hydrolyze the muropeptides from L. casei cell walls. Both fusions bound to mucin, collagen and to intestinal epithelial cells and, similar to L. rhamnosus GG p40, stimulated epidermal growth factor receptor phosphorylation in mouse intestine ex vivo. These results indicate that extracellular proteins belonging to the machinery of cell-wall metabolism in the closely related L. casei/paracasei-L. rhamnosus group are most likely involved in the probiotic effects described for these bacteria PMID:21178363

A New Mechanism for the Regulation of Stomatal Aperture Size in Intact Leaves (Accumulation of Mesophyll-Derived Sucrose in the Guard-Cell Wall of Vicia faba).

PubMed Central

Lu, P.; Outlaw Jr, W. H.; Smith, B. G.; Freed, G. A.

1997-01-01

At various times after pulse-labeling broad bean (Vicia faba L.) leaflets with 14CO2, whole-leaf pieces and rinsed epidermal peels were harvested and subsequently processed for histochemical analysis. Cells dissected from whole leaf retained apoplastic contents, whereas those from rinsed peels contained only symplastic contents. Sucrose (Suc)-specific radioactivity peaked (111 GBq mol-1) in palisade cells at 20 min. In contrast, the 14C content and Sucspecific radioactivity were very low in guard cells for 20 min, implying little CO2 incorporation; both then peaked at 40 min. The guard-cell apoplast had a high maximum Suc-specific radioactivity (204 GBq mol-1) and a high Suc influx rate (0.05 pmol stoma-1 min-1). These and other comparisons implied the presence of (a) multiple Suc pools in mesophyll cells, (b) a localized mesophyll-apoplast region that exchanges with phloem and stomata, and (c) mesophyll-derived Suc in guard-cell walls sufficient to diminish stomatal opening by approximately 3 [mu]m. Factors expected to enhance Suc accumulation in guard-cell walls are (a) high transpiration rate, which closes stomata, and (b) high apoplastic Suc concentration, which is elevated when mesophyll Suc efflux exceeds translocation. Therefore, multiple physiological factors are integrated in the attenuation of stomatal aperture size by this previously unrecognized mechanism. PMID:12223693

Labellar anatomy and secretion in Bulbophyllum Thouars (Orchidaceae: Bulbophyllinae) sect. Racemosae Benth. & Hook. f.

PubMed Central

Davies, Kevin L.; Stpiczyńska, Malgorzata

2014-01-01

Background and Aims Floral secretions are common in Bulbophyllum Thouars, and the labella of a number of Asian species are said to produce secretions rich in lipids that act as food rewards for insect pollinators. Although some of these reports are based on simple histochemical tests, a much greater number are anecdotal and, hitherto, neither the ultrastructure of the labellum nor the secretory process has been investigated in detail. Furthermore, sophisticated histochemical approaches have generally not been applied. Here, both the labellar structure and the secretory process are investigated for four species of Asian Bulbophyllum sect. Racemosae Benth. & Hook. f., namely Bulbophyllum careyanum (Hook.) Spreng., B. morphologorum Kraenzl., B. orientale Seidenf. and B. wangkaense Seidenf., and compared with those of unequivocal lipid-secreting orchids. Methods Labellar, secretory tissue was investigated using light microscopy, scanning electron microscopy, transmission electron microscopy and histochemistry. Key Results The adaxial median longitudinal groove of the labellum contained secretory tissue comprising palisade-like epidermal cells, similar to those of certain lipid-secreting Oncidiinae Benth. However, these cells and their secretions gave positive results mainly for protein and mucilage, and their organelle complement was consistent with that of cells involved in protein and mucilage synthesis. Sub-cuticular accumulation of secretion resulted in cuticular distension and blistering. The sub-epidermal layer of isodiametric parenchyma contained starch and, like the epidermal cells, ultrastructure consistent with mucilage synthesis. Lipids were mainly confined to the cuticle, and hardly any intracellular lipid droplets were observed. Conclusions It is proposed that mucilage is produced by dictyosomes present in the palisade-like epidermal cells. Mucilage precursors may also be produced by these same organelles in sub-epidermal cells and are thought to pass along the symplast via plasmodesmata into the adjoining palisade-like secretory cells, which contain abundant arrays of rough endoplasmic reticulum. Here, they become chemically modified and form a protein-rich, mucilaginous secretion that, following vesicle-mediated transport across the cytoplasm, traverses the cell wall and accumulates in blisters formed from the distended cuticle. Rupture of these blisters releases the secretion onto the labellar surface. However, in certain species, there is some evidence that the secretion may traverse the cuticle via cuticular pores, and micro-channels may permit the passage of fragrance. Hydrolysis of sub-epidermal starch probably generates the carbohydrate and, together with mitochondria, much of the energy required for the secretory process. This anatomical organization resembles that found in certain lipid-secreting, Neotropical species of Bulbophyllum and Oncidiinae, but since the chemical composition of their secretions is different, and these taxa occur on a separate continent and have different insect pollinators, parallelism of floral anatomy is likely. PMID:25122654

Adult epidermal Notch activity induces dermal accumulation of T cells and neural crest derivatives through upregulation of jagged 1.

PubMed

Ambler, Carrie A; Watt, Fiona M

2010-11-01

Notch signalling regulates epidermal differentiation and tumour formation via non-cell autonomous mechanisms that are incompletely understood. This study shows that epidermal Notch activation via a 4-hydroxy-tamoxifen-inducible transgene caused epidermal thickening, focal detachment from the underlying dermis and hair clumping. In addition, there was dermal accumulation of T lymphocytes and stromal cells, some of which localised to the blisters at the epidermal-dermal boundary. The T cell infiltrate was responsible for hair clumping but not for other Notch phenotypes. Notch-induced stromal cells were heterogeneous, expressing markers of neural crest, melanocytes, smooth muscle and peripheral nerve. Although Slug1 expression was expanded in the epidermis, the stromal cells did not arise through epithelial-mesenchymal transition. Epidermal Notch activation resulted in upregulation of jagged 1 in both epidermis and dermis. When Notch was activated in the absence of epidermal jagged 1, jagged 1 was not upregulated in the dermis, and epidermal thickening, blister formation, accumulation of T cells and stromal cells were inhibited. Gene expression profiling revealed that epidermal Notch activation resulted in upregulation of several growth factors and cytokines, including TNFα, the expression of which was dependent on epidermal jagged 1. We conclude that jagged 1 is a key mediator of non-cell autonomous Notch signalling in skin.

Ectopic expression of Capsicum-specific cell wall protein Capsicum annuum senescence-delaying 1 (CaSD1) delays senescence and induces trichome formation in Nicotiana benthamiana.

PubMed

Seo, Eunyoung; Yeom, Seon-In; Jo, Sunghwan; Jeong, Heejin; Kang, Byoung-Cheorl; Choi, Doil

2012-04-01

Secreted proteins are known to have multiple roles in plant development, metabolism, and stress response. In a previous study to understand the roles of secreted proteins, Capsicum annuum secreted proteins (CaS) were isolated by yeast secretion trap. Among the secreted proteins, we further characterized Capsicum annuum senescence-delaying 1 (CaSD1), a gene encoding a novel secreted protein that is present only in the genus Capsicum. The deduced CaSD1 contains multiple repeats of the amino acid sequence KPPIHNHKPTDYDRS. Interestingly, the number of repeats varied among cultivars and species in the Capsicum genus. CaSD1 is constitutively expressed in roots, and Agrobacterium-mediated transient overexpression of CaSD1 in Nicotiana benthamiana leaves resulted in delayed senescence with a dramatically increased number of trichomes and enlarged epidermal cells. Furthermore, senescence- and cell division-related genes were differentially regulated by CaSD1-overexpressing plants. These observations imply that the pepper-specific cell wall protein CaSD1 plays roles in plant growth and development by regulating cell division and differentiation.

Adult epidermal Notch activity induces dermal accumulation of T cells and neural crest derivatives through upregulation of jagged 1

PubMed Central

Ambler, Carrie A.; Watt, Fiona M.

2010-01-01

Notch signalling regulates epidermal differentiation and tumour formation via non-cell autonomous mechanisms that are incompletely understood. This study shows that epidermal Notch activation via a 4-hydroxy-tamoxifen-inducible transgene caused epidermal thickening, focal detachment from the underlying dermis and hair clumping. In addition, there was dermal accumulation of T lymphocytes and stromal cells, some of which localised to the blisters at the epidermal-dermal boundary. The T cell infiltrate was responsible for hair clumping but not for other Notch phenotypes. Notch-induced stromal cells were heterogeneous, expressing markers of neural crest, melanocytes, smooth muscle and peripheral nerve. Although Slug1 expression was expanded in the epidermis, the stromal cells did not arise through epithelial-mesenchymal transition. Epidermal Notch activation resulted in upregulation of jagged 1 in both epidermis and dermis. When Notch was activated in the absence of epidermal jagged 1, jagged 1 was not upregulated in the dermis, and epidermal thickening, blister formation, accumulation of T cells and stromal cells were inhibited. Gene expression profiling revealed that epidermal Notch activation resulted in upregulation of several growth factors and cytokines, including TNFα, the expression of which was dependent on epidermal jagged 1. We conclude that jagged 1 is a key mediator of non-cell autonomous Notch signalling in skin. PMID:20940224

Vascularization, high-volume solution flow, and localized roles for enzymes of sucrose metabolism during tumorigenesis by Agrobacterium tumefaciens.

PubMed

Wächter, Rebecca; Langhans, Markus; Aloni, Roni; Götz, Simone; Weilmünster, Anke; Koops, Ariane; Temguia, Leopoldine; Mistrik, Igor; Pavlovkin, Jan; Rascher, Uwe; Schwalm, Katja; Koch, Karen E; Ullrich, Cornelia I

2003-11-01

Vascular differentiation and epidermal disruption are associated with establishment of tumors induced by Agrobacterium tumefaciens. Here, we address the relationship of these processes to the redirection of nutrient-bearing water flow and carbohydrate delivery for tumor growth within the castor bean (Ricinus communis) host. Treatment with aminoethoxyvinyl-glycine showed that vascular differentiation and epidermal disruption were central to ethylene-dependent tumor establishment. CO2 release paralleled tumor growth, but water flow increased dramatically during the first 3 weeks. However, tumor water loss contributed little to water flow to host shoots. Tumor water loss was followed by accumulation of the osmoprotectants, sucrose (Suc) and proline, in the tumor periphery, shifting hexose-to-Suc balance in favor of sugar signals for maturation and desiccation tolerance. Concurrent activities and sites of action for enzymes of Suc metabolism changed: Vacuolar invertase predominated during initial import of Suc into the symplastic continuum, corresponding to hexose concentrations in expanding tumors. Later, Suc synthase (SuSy) and cell wall invertase rose in the tumor periphery to modulate both Suc accumulation and descending turgor for import by metabolization. Sites of abscisic acid immunolocalization correlated with both central vacuolar invertase and peripheral cell wall invertase. Vascular roles were indicated by SuSy immunolocalization in xylem parenchyma for inorganic nutrient uptake and in phloem, where resolution allowed SuSy identification in sieve elements and companion cells, which has widespread implications for SuSy function in transport. Together, data indicate key roles for ethylene-dependent vascularization and cuticular disruption in the redirection of water flow and carbohydrate transport for successful tumor establishment.

[Enhanced lymphocyte proliferation in the presence of epidermal cells of HIV-infected patients in vitro].

PubMed

Kappus, R P; Berger, S; Thomas, C A; Ottmann, O G; Ganser, A; Stille, W; Shah, P M

1992-07-01

Clinical observations show that the HIV infection is often associated with affections of the skin. In order to examine the involvement of the epidermal immune system in the HIV infection, we determined accessory cell function of epidermal cells from HIV-1-infected patients. For this we measured the proliferative response of enriched CD(4+)-T-lymphocytes from HIV-infected patients and noninfected controls to stimulation with anti-CD3 and IL-2 in the presence of epidermal cells; the enhancement of the response is dependent on the presence of functionally intact accessory cells. The capacity of epidermal cells to increase the anti-CD3-stimulated T-cell proliferative response was significantly enhanced in HIV patients (CDC III/IVA) as compared with noninfected donors. It is discussed, whether the increased activity of epidermal cells from HIV-infected patients may be responsible for several of the dermal lesions in the course of an HIV infection as due to an enhanced production and release of epidermal cell-derived cytokines.

Morphological and functional studies on the epidermal cells of amphioxus ( Branchiostoma belcheri tsingtauense) at different developmental stages

NASA Astrophysics Data System (ADS)

Mao, Bing-Yu; Sun, Xiao-Yang; Zhang, Hong-Wei; Zhang, Shi-Cui; Wu, Xian-Han

1997-09-01

Epidermal cells of amphioxus at different developmental stages were investigated by electron microscopy and colloidal carbon tracing experiments. Amphioxus epidermal cells showed different ultrastructural characteristics at larval and adult stages. The epidermal cells at all larval stages studied (24 96 h) had numerous vesicles containing electron dense materials in their apical cytoplasm. In tracing experiments, carbon particles were found in apical vesicles and interoellular spaces. Under scanning electron microscope, many crater-like protrusions were observed on the surface of the cells. These results indicated that amphioxus larval epidermal cells may be capable of endocytosis. The epidermal cells of 3-month and adult amphioxus were obviously secretory ones characterized by well-developed peripheral filaments, a prominent Golgi apparatus and abundant apical secretory vesicles. This study also showed that adult amphioxus body surface mucus contained lectin that could agglutinate human red blood cells. The authors propose that the epidermal cells of amphioxus larva and adult may contribute to the immune defense of the amimal by different means.

Differentiated epidermal cells regain the ability to regenerate a skin equivalent by increasing the level of β-catenin in the cells.

PubMed

Zhao, Zhili; Zhang, Cuiping; Fu, Xiaobing; Yang, Rongya; Peng, Chen; Gu, Tingmin; Sui, Zhifu; Wang, Congmin; Liu, Chang

2012-01-01

Epidermal stem cells are of major importance for skin regeneration and tissue engineering, but differentiated epidermal cells lost their proliferative capacity and are no longer able to regenerate a skin equivalent. Here, we investigated the role of β-catenin in regulating regenerative functions of differentiated epidermal cells. Lithium chloride and a highly specific glycogen synthase kinase (GSK)-3β inhibitor were applied to induce the expression of β-catenin in differentiated epidermal cells. After a 6-day induction, the large flat-shaped cells with a small nuclear-cytoplasmic ratio had changed into small round-shaped cells with a large nuclear-cytoplasmic ratio. Phenotypic assays showed a remarkably higher expression of CK19, β(1)-integrin, Oct4 and Nanog in induced cells than in the control group (p < 0.01). In addition, the results of growth and functional investigations demonstrated that the induced epidermal cells exhibited a high colony-forming ability, a long-term proliferative potential and the ability to regenerate a skin equivalent, which were regarded as the most important features of epidermal stem cells. These results suggest that the activation of β-catenin favors the reversion or dedifferentiation of differentiated epidermal cells to an immature or a less differentiated state. This study may also offer a new approach to yield enough epidermal stem cells for skin regeneration and tissue engineering. Copyright © 2012 S. Karger AG, Basel.

Overexpression of AtLOV1 in Switchgrass alters plant architecture, lignin content, and flowering time.

PubMed

Xu, Bin; Sathitsuksanoh, Noppadon; Tang, Yuhong; Udvardi, Michael K; Zhang, Ji-Yi; Shen, Zhengxing; Balota, Maria; Harich, Kim; Zhang, Percival Y-H; Zhao, Bingyu

2012-01-01

Switchgrass (Panicum virgatum L.) is a prime candidate crop for biofuel feedstock production in the United States. As it is a self-incompatible polyploid perennial species, breeding elite and stable switchgrass cultivars with traditional breeding methods is very challenging. Translational genomics may contribute significantly to the genetic improvement of switchgrass, especially for the incorporation of elite traits that are absent in natural switchgrass populations. In this study, we constitutively expressed an Arabidopsis NAC transcriptional factor gene, LONG VEGETATIVE PHASE ONE (AtLOV1), in switchgrass. Overexpression of AtLOV1 in switchgrass caused the plants to have a smaller leaf angle by changing the morphology and organization of epidermal cells in the leaf collar region. Also, overexpression of AtLOV1 altered the lignin content and the monolignol composition of cell walls, and caused delayed flowering time. Global gene-expression analysis of the transgenic plants revealed an array of responding genes with predicted functions in plant development, cell wall biosynthesis, and flowering. To our knowledge, this is the first report of a single ectopically expressed transcription factor altering the leaf angle, cell wall composition, and flowering time of switchgrass, therefore demonstrating the potential advantage of translational genomics for the genetic improvement of this crop.

Plant, cell, and molecular mechanisms of abscisic-acid regulation of stomatal apertures. A new mechanism for the regulation of stomatal-aperture size in intact leaves: Accumulation of mesophyll-derived sucrose in the guard-cell wall of Vicia faba L.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, P.; Outlaw, W.H. Jr.; Smith, B.G.

At various times after pulse labeling Vicia faba L. leaflets with {sup 14}CO{sub 2}, whole-leaf pieces and rinsed epidermal peels were harvested and subsequently processed for histochemical analysis. Cells dissected from whole leaf retained apoplastic contents whereas those from rinsed peels contained only cytoplastic contents. Sucrose specific radioactivity peaked in palisade cells, 111 GBq{center_dot}mol{sup {minus}1}, at 20 min. In contrast, the {sup 14}C content and sucrose specific radioactivity were very low in guard cells for 20 min, implying little CO{sub 2} incorporation; both then peaked at 40 min. The guard-cell apoplast had a high maximum sucrose specific radioactivity and amore » high sucrose influx rate. These and other comparisons implied the presence of (a) multiple sucrose pools in mesophyll cells, (b) a localized mesophyll-apoplast region that exchanges with phloem and stomata, and (c) mesophyll-derived sucrose in guard-cell walls sufficient to diminish stomatal opening by {approximately} 4 {micro}m. Factors expected to enhance sucrose accumulation in guard-cell walls are (a) high transpiration rate, which closes stomata, and (b) high apoplastic sucrose concentration, which is elevated when mesophyll-sucrose efflux exceeds translocation. Therefore, multiple physiological factors are integrated in the attenuation of stomatal-aperture size by this previously unrecognized mechanism.« less

Regenerative and reparative effects of human chorion-derived stem cell conditioned medium on photo-aged epidermal cells

PubMed Central

Li, Qiankun; Chen, Yan; Ma, Kui; Zhao, Along; Zhang, Cuiping; Fu, Xiaobing

2016-01-01

ABSTRACT Epidermal cells are an important regenerative source for skin wound healing. Aged epidermal cells have a low ability to renew themselves and repair skin injury. Ultraviolet (UV) radiation, particularly UVB, can cause photo-aging of the skin by suppressing the viability of human epidermal cells. A chorion-derived stem cell conditioned medium (CDSC-CNM) is thought to have regenerative properties. This study aimed to determine the regenerative effects of CDSC-CNM on UVB-induced photo-aged epidermal cells. Epidermal cells were passaged four times and irradiated with quantitative UVB, and non-irradiated cells served as a control group. Cells were then treated with different concentrations of CDSC-CNM. Compared to the non-irradiated group, the proliferation rates and migration rates of UVB-induced photo-aged epidermal cells significantly decreased (p < 0.05) with increasing intracellular radical oxygen species (ROS) generation and DNA damage. After treatment with CDSC-CNM, photo-aged epidermal cells significantly improved their viability, and their ROS generation and DNA damage decreased. The secretory factors in CDSC-CNM, including epidermal growth factor (EGF), transforming growth factor-β (TGF-β), interleukin (IL)-6, and IL-8 and the related signaling pathway protein levels, increased compared to the control medium (CM). The potential regenerative and reparative effects of CDSC-CNM indicate that it may be a candidate material for the treatment of prematurely aged skin. The functions of the secretory factors and the mechanisms of CDSC-CNM therapy deserve further attention. PMID:27097375

Stromal cell-derived factor 1 (SDF-1) accelerated skin wound healing by promoting the migration and proliferation of epidermal stem cells.

PubMed

Guo, Rui; Chai, Linlin; Chen, Liang; Chen, Wenguang; Ge, Liangpeng; Li, Xiaoge; Li, Hongli; Li, Shirong; Cao, Chuan

2015-06-01

Epidermal stem cells could contribute to skin repair through the migration of cells from the neighboring uninjured epidermis, infundibulum, hair follicle, or sebaceous gland. However, little is known about the factors responsible for the complex biological processes in wound healing. Herein, we will show that the attracting chemokine, SDF-1/CXCR4, is a major regulator involved in the migration of epidermal stem cells during wound repair. We found that the SDF-1 levels were markedly increased at the wound margins following injury and CXCR4 expressed in epidermal stem cells and proliferating epithelial cells. Blocking the SDF-1/CXCR4 axis resulted in a significant reduction in epidermal stem cell migration toward SDF-1 in vitro and delayed wound healing in vivo, while an SDF-1 treatment enhanced epidermal stem cell migration and proliferation and accelerated wound healing. These results provide direct evidence that SDF-1 promotes epidermal stem cell migration, accelerates skin regeneration, and makes the development of new regenerative therapeutic strategies for wound healing possible.

Effects of adenosine 5'-monophosphate on epidermal turnover.

PubMed

Furukawa, Fukumi; Kanehara, Shoko; Harano, Fumiki; Shinohara, Shigeo; Kamimura, Junko; Kawabata, Shigekatsu; Igarashi, Sachiyo; Kawamura, Mitsuaki; Yamamoto, Yuki; Miyachi, Yoshiki

2008-10-01

The structure and function of the epidermis is maintained by cell renewal based on epidermal turnover. Epidermal turnover is delayed by aging, and it is thought that the delay of the epidermal turnover is a cause of aging alternation of skin. The epidermal turnover is related to the energy metabolism of epidermal basal cells. Adenosine 5'-triphosphate (ATP) is needed for cell renewal: cell division, and adenosine 5'-monophosphate (AMP) increases the amount of intracellular ATP. These findings suggest that AMP accelerates the epidermal turnover delayed by aging. This study investigated whether AMP and adenosine 5'-monophosphate disodium salt (AMP2Na) accelerates the epidermal turnover. An effect of AMP2Na on cell proliferation was examined by our counting of keratinocytes. An effect of AMP2Na on cell cycle was examined by our counting of basal cells in DNA synthetic period of hairless rats. The effects of AMP2Na (or AMP) on the epidermal turnover were examined by our measuring stratum corneum transit time by use of guinea pigs, and by our measuring stratum corneum surface area by use of hairless rats and in a clinical pharmacological study. The AMP2Na showed two different profiles on the proliferation of primary cultured keratinocytes. At a low concentration it induced cell growth, whereas at a high concentration it inhibited cell growth. The number of basal cells in the DNA synthetic period of AMP2Na was significantly higher than that of the vehicle in hairless rats. The stratum corneum transit time of AMP2Na was significantly shorter than that of the vehicle in guinea pigs. The corneocyte surface area of emulsion containing AMP2Na was significantly smaller than that of the vehicle in volunteers. We conclude that AMP promotes the cell proliferation and the cell cycle progression of epidermal basal cells and accelerates epidermal turnover safely. In addition, AMP is useful for skin rejuvenation in dermatology and aesthetic dermatology.

Gravitropism of cucumber hypocotyls: biophysical mechanism of altered growth

NASA Technical Reports Server (NTRS)

Cosgrove, D. J.

1990-01-01

The biophysical basis for the changes in cell elongation rate during gravitropism was examined in aetiolated cucumber (Cucumis sativus L.) hypocotyls. Bulk osmotic pressures on the two sides of the stem and in the epidermal cells were not altered during the early time course of gravitropism. By the pressure-probe technique, a small increase in turgor (0.3 bar, 30 kPa) was detected on the upper (inhibited) side, whereas there was a negligible decrease in turgor on the lower (stimulated) side. These small changes in turgor and water potential appeared to be indirect, passive consequences of the altered growth and the small resistance for water movement from the xylem, and indicated that the change in growth was principally due to changes in wall properties. The results indicate that the hydraulic conductance of the water-transport pathway was large (.25 h-1 bar-1) and the water potential difference supporting cell expansion was no greater than 0.3 bar (30 kPa). From pressure-block experiments, it appeared that upon gravitropic stimulation (1) the yield threshold of the lower half of the stem did not decrease and (2) the wall on the upper side of the stem was not made more rigid by a cross-linking process. Mechanical measurements of the stress/strain properties of the walls showed that the initial development of gravitropism did not involve an alteration of the mechanical behaviour of the isolated walls. Thus, gravitropism in cucumber hypocotyls occurs principally by an alteration of the wall relaxation process, without a necessary change in wall mechanical properties.

Herbicide effects on cuticle ultrastructure in Eleusine indica and Portulaca oleracea.

PubMed

Malpassi, Rosana N

2006-04-01

Eleusine indica and Portulaca oleracea are two common weeds in peanut crops in southern Córdoba. Two chemicals are frequently used to control them, quizalofop for grasses and lactofen for dicots. The objective is to study the effects of quizalofop and lactofen on cuticle ultrastructure in E. indica and P. oleracea, respectively. In the lab, quizalofop was applied on E. indica and lactofen on P. oleracea. Three plant categories were analyzed in each species: 3, 1-2, and no tiller in E. indica, and 8, 6, and 2 nomophylls in P. oleracea. Leaf samples from both species were collected at 7 and 16 days post-application and were treated for scanning electron microscopy. E. indica cuticle treated with lethal dose shows areas where epicuticular waxes disappear, specially in the youngest individuals. These areas are located predominantly on periclinal walls of typical epidermic cells and subsidiary cells. On the other hand, P. oleracea shows cuticle discontinuities that may be caused by lactofen entry. They are smaller and less frequent in plants having 8 or more nomophylls. The remaining waxes act as a herbicide accumulation compartment and, therefore, would partially prevent the active ingredient entry to epidermic cells.

A new mechanism for the regulation of stomatal aperture size in intact leaves: Accumulation of mesophyll-derived sucrose in the guard-cell wall of Vicia faba

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Ping; Outlaw, W.H. Jr.; Smith, B.G.

At various times after pulse-labeling broad bean (Vicia faba L.) leaflets with {sup 14}CO{sub 2}, whole-leaf pieces and rinsed epidermal peels were harvested and subsequently processed for histochemical analysis. Cells dissected from whole leaf retained apoplastic contents, whereas those from rinsed peels contained only symplastic contents. Sucrose (Suc)-specific radioactivity peaked (111 GBq mol{sup -1}) in palisade cells at 20 min. In contrast, the {sup 14}C content and Suc-specific radioactivity were very low in guard cells for 20 min, implying little CO, incorporation; both then peaked at 40 min. The guard-cell apoplast had a high maximum Suc-specific radioactivity (204 GBq mol{supmore » -1}) and a high Suc influx rate (0.05 pmol stoma{sup -1} min{sup -1}). These and other comparisons implied the presence of (a) multiple Suc pools in mesophyll cells, M a localized mesophyll-apoplast region that exchanges with phloem and stomata, and mesophyll-derived Suc in guard-cell walls sufficient to diminish stomatal opening by approximately 3 pm. Factors expected to enhance Suc accumulation in guard-cell walls are (a) high transpiration rate, which closes stomata, and N high apoplastic Suc concentration, which is elevated when mesophyll Suc efflux exceeds translocation. Therefore, multiple physiological factors are integrated in the attenuation of stomatal aperture size by this previously unrecognized mechanism. 50 refs., 9 figs.« less

Design of antibody-functionalized carbon nanotubes filled with radioactivable metals towards a targeted anticancer therapy

NASA Astrophysics Data System (ADS)

Spinato, Cinzia; Perez Ruiz de Garibay, Aritz; Kierkowicz, Magdalena; Pach, Elzbieta; Martincic, Markus; Klippstein, Rebecca; Bourgognon, Maxime; Wang, Julie Tzu-Wen; Ménard-Moyon, Cécilia; Al-Jamal, Khuloud T.; Ballesteros, Belén; Tobias, Gerard; Bianco, Alberto

2016-06-01

In the present work we have devised the synthesis of a novel promising carbon nanotube carrier for the targeted delivery of radioactivity, through a combination of endohedral and exohedral functionalization. Steam-purified single-walled carbon nanotubes (SWCNTs) have been initially filled with radioactive analogues (i.e. metal halides) and sealed by high temperature treatment, affording closed-ended CNTs with the filling material confined in the inner cavity. The external functionalization of these filled CNTs was then achieved by nitrene cycloaddition and followed by the derivatization with a monoclonal antibody (Cetuximab) targeting the epidermal growth factor receptor (EGFR), overexpressed by several cancer cells. The targeting efficiency of the so-obtained conjugate was evaluated by immunostaining with a secondary antibody and by incubation of the CNTs with EGFR positive cells (U87-EGFR+), followed by flow cytometry, confocal microscopy or elemental analyses. We demonstrated that our filled and functionalized CNTs can internalize more efficiently in EGFR positive cancer cells.In the present work we have devised the synthesis of a novel promising carbon nanotube carrier for the targeted delivery of radioactivity, through a combination of endohedral and exohedral functionalization. Steam-purified single-walled carbon nanotubes (SWCNTs) have been initially filled with radioactive analogues (i.e. metal halides) and sealed by high temperature treatment, affording closed-ended CNTs with the filling material confined in the inner cavity. The external functionalization of these filled CNTs was then achieved by nitrene cycloaddition and followed by the derivatization with a monoclonal antibody (Cetuximab) targeting the epidermal growth factor receptor (EGFR), overexpressed by several cancer cells. The targeting efficiency of the so-obtained conjugate was evaluated by immunostaining with a secondary antibody and by incubation of the CNTs with EGFR positive cells (U87-EGFR+), followed by flow cytometry, confocal microscopy or elemental analyses. We demonstrated that our filled and functionalized CNTs can internalize more efficiently in EGFR positive cancer cells. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07923c

New procedure for epidermal cell isolation using kiwi fruit actinidin, and improved culture of melanocytes in the presence of leukaemia inhibitory factor and forskolin.

PubMed

Yarani, Reza; Mansouri, Kamran; Mohammadi-Motlagh, Hamid Reza; Bakhtiari, Mitra; Mostafaie, Ali

2013-06-01

Conventional isolation of epidermis from the dermis and disruption of epidermal sheets to liberate the cells, are performed using proteolytic enzymes such as thermolysin or collagenase. Selective population expansion of melanocytes is achieved by suppressing proliferation of keratinocytes and fibroblasts in epidermal cell suspensions, using phorbol esters and cholera toxin. Here, we introduce a new procedure for isolation of epidermal cells, using proteolytic activity of kiwi fruit actinidin, and also an improved growth medium for melanocytes in the presence of leukaemia inhibitory factor (LIF) and forskolin. Dermo-epidermal separation and epidermal sheet cell dispersion were performed using actinidin compared to conventional proteases including collagenase, thermolysin or trypsin. Thereafter, melanocyte culture was performed in two common media and one modified medium to discover optimization for these cells. We found that dermo-epidermal separation and epidermal sheet cell dispersion using kiwi fruit actinidin were considerably better than previously used methods, both from the aspect of less fibroblast and keratinocyte contamination, and of more viable native cells. Also, melanocytes proliferated better in phorbol ester- and cholera toxin-free proliferation medium supplemented with LIF and forskolin. Less contamination and higher numbers of viable cells were actinidin preferential for separation of epidermis and isolation of epidermal cells. Supplementation of LIF and forskolin to new medium increased proliferation potential of melanocytes in comparison to exogenous mitogens. © 2013 Blackwell Publishing Ltd.

Evolution and genetics of root hair stripes in the root epidermis.

PubMed

Dolan, L; Costa, S

2001-03-01

Root hair pattern develops in a number of different ways in angiosperm. Cells in the epidermis of some species undergo asymmetric cell divisions to form a smaller daughter cell from which a hair grows, and a larger cell that forms a non-hair epidermal cell. In other species any cell in the epidermis can form a root hair. Hair cells are arranged in files along the Arabidopsis root, located in the gaps between underlying cortical cell files. Epidermal cells overlying a single cortical cell file develop as non-hair epidermal cells. Genetic analysis has identified a transcription factor cascade required for the formation of this pattern. WEREWOLF (WER) and GLABRA2 (GL2) are required for the formation of non-hair epidermal cells while CAPRICE (CPC) is required for hair cell development. Recent analyses of the pattern of epidermal cells among the angiosperms indicate that this striped pattern of cell organization evolved from non-striped ancestors independently in a number of diverse evolutionary lineages. The genetic basis for the evolution of epidermal pattern in angiosperms may now be examined.

Labellar anatomy and secretion in Bulbophyllum Thouars (Orchidaceae: Bulbophyllinae) sect. Racemosae Benth. & Hook. f.

PubMed

Davies, Kevin L; Stpiczyńska, Malgorzata

2014-10-01

Floral secretions are common in Bulbophyllum Thouars, and the labella of a number of Asian species are said to produce secretions rich in lipids that act as food rewards for insect pollinators. Although some of these reports are based on simple histochemical tests, a much greater number are anecdotal and, hitherto, neither the ultrastructure of the labellum nor the secretory process has been investigated in detail. Furthermore, sophisticated histochemical approaches have generally not been applied. Here, both the labellar structure and the secretory process are investigated for four species of Asian Bulbophyllum sect. Racemosae Benth. & Hook. f., namely Bulbophyllum careyanum (Hook.) Spreng., B. morphologorum Kraenzl., B. orientale Seidenf. and B. wangkaense Seidenf., and compared with those of unequivocal lipid-secreting orchids. Labellar, secretory tissue was investigated using light microscopy, scanning electron microscopy, transmission electron microscopy and histochemistry. The adaxial median longitudinal groove of the labellum contained secretory tissue comprising palisade-like epidermal cells, similar to those of certain lipid-secreting Oncidiinae Benth. However, these cells and their secretions gave positive results mainly for protein and mucilage, and their organelle complement was consistent with that of cells involved in protein and mucilage synthesis. Sub-cuticular accumulation of secretion resulted in cuticular distension and blistering. The sub-epidermal layer of isodiametric parenchyma contained starch and, like the epidermal cells, ultrastructure consistent with mucilage synthesis. Lipids were mainly confined to the cuticle, and hardly any intracellular lipid droplets were observed. It is proposed that mucilage is produced by dictyosomes present in the palisade-like epidermal cells. Mucilage precursors may also be produced by these same organelles in sub-epidermal cells and are thought to pass along the symplast via plasmodesmata into the adjoining palisade-like secretory cells, which contain abundant arrays of rough endoplasmic reticulum. Here, they become chemically modified and form a protein-rich, mucilaginous secretion that, following vesicle-mediated transport across the cytoplasm, traverses the cell wall and accumulates in blisters formed from the distended cuticle. Rupture of these blisters releases the secretion onto the labellar surface. However, in certain species, there is some evidence that the secretion may traverse the cuticle via cuticular pores, and micro-channels may permit the passage of fragrance. Hydrolysis of sub-epidermal starch probably generates the carbohydrate and, together with mitochondria, much of the energy required for the secretory process. This anatomical organization resembles that found in certain lipid-secreting, Neotropical species of Bulbophyllum and Oncidiinae, but since the chemical composition of their secretions is different, and these taxa occur on a separate continent and have different insect pollinators, parallelism of floral anatomy is likely. © The Author 2014. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Stylostome organization in feeding Leptotrombidium larvae (Acariformes: Trombiculidae).

PubMed

Shatrov, Andrew B; Takahashi, Mamoru; Noda, Shinichi; Misumi, Hitoko

2014-01-01

The stylostome of larvae of the trombiculids Leptotrombidium scutellare (Nagayo et al.), Leptotrombidium fletcheri (Womersley et Heaslip) and Leptotrombidium deliense (Walch) was studied experimentally at different time intervals after larval attachment using the histological method. The stylostome of these species has the same organization and belongs to the epidermal combined with the mixed type, developing more in width than in length. Neither transverse nor conspicuous longitudinal layers are present within the stylostome walls, which stain predominantly in red with Azan, also showing longitudinal portions with blue staining. Larvae tend to attach closely to each other and scabs, consisting of the hyperkeratotic epidermal layers fusing with migrating inflammatory cells, develop around the attachment sites. The dermis shows inflammatory foci with dilated capillaries and inflammatory cells inserting in the connective tissue layer underneath the stylostome. The feeding cavity, which is moderately expressed, may be found either in the epidermis or in the dermis. It contains inflammatory cells and their debris in the liquefied host tissues. The stylostome length depends on the character of the attachment site (the thicker epidermis or scab the longer the stylostome), and does not directly correspond to the stages of larval feeding. Nevertheless, at the 48-h time interval, nearly all attached larvae are found to be fully fed and their midgut cells are filled with nutritional globules.

JACKDAW controls epidermal patterning in the Arabidopsis root meristem through a non-cell-autonomous mechanism.

PubMed

Hassan, Hala; Scheres, Ben; Blilou, Ikram

2010-05-01

In Arabidopsis, specification of the hair and non-hair epidermal cell types is position dependent, in that hair cells arise over clefts in the underlying cortical cell layer. Epidermal patterning is determined by a network of transcriptional regulators that respond to an as yet unknown cue from underlying tissues. Previously, we showed that JACKDAW (JKD), a zinc finger protein, localizes in the quiescent centre and the ground tissue, and regulates tissue boundaries and asymmetric cell division by delimiting SHORT-ROOT movement. Here, we provide evidence that JKD controls position-dependent signals that regulate epidermal-cell-type patterning. JKD is required for appropriately patterned expression of the epidermal cell fate regulators GLABRA2, CAPRICE and WEREWOLF. Genetic interaction studies indicate that JKD operates upstream of the epidermal patterning network in a SCRAMBLED (SCM)-dependent fashion after embryogenesis, but acts independent of SCM in embryogenesis. Tissue-specific induction experiments indicate non-cell-autonomous action of JKD from the underlying cortex cell layer to specify epidermal cell fate. Our findings are consistent with a model where JKD induces a signal in every cortex cell that is more abundant in the hair cell position owing to the larger surface contact of cells located over a cleft.

Wounding coordinately induces cell wall protein, cell cycle and pectin methyl esterase genes involved in tuber closing layer and wound periderm development.

PubMed

Neubauer, Jonathan D; Lulai, Edward C; Thompson, Asunta L; Suttle, Jeffrey C; Bolton, Melvin D

2012-04-15

Little is known about the coordinate induction of genes that may be involved in agriculturally important wound-healing events. In this study, wound-healing events were determined together with wound-induced expression profiles of selected cell cycle, cell wall protein, and pectin methyl esterase genes using two diverse potato genotypes and two harvests (NDTX4271-5R and Russet Burbank tubers; 2008 and 2009 harvests). By 5 d after wounding, the closing layer and a nascent phellogen had formed. Phellogen cell divisions generated phellem layers until cessation of cell division at 28 d after wounding for both genotypes and harvests. Cell cycle genes encoding epidermal growth factor binding protein (StEBP), cyclin-dependent kinase B (StCDKB) and cyclin-dependent kinase regulatory subunit (StCKS1At) were induced by 1 d after wounding; these expressions coordinated with related phellogen formation and the induction and cessation of phellem cell formation. Genes encoding the structural cell wall proteins extensin (StExt1) and extensin-like (StExtlk) were dramatically up-regulated by 1-5 d after wounding, suggesting involvement with closing layer and later phellem cell layer formation. Wounding up-regulated pectin methyl esterase genes (StPME and StPrePME); StPME expression increased during closing layer and phellem cell formation, whereas maximum expression of StPrePME occurred at 5-14 d after wounding, implicating involvement in later modifications for closing layer and phellem cell formation. The coordinate induction and expression profile of StTLRP, a gene encoding a cell wall strengthening "tyrosine-and lysine-rich protein," suggested a role in the formation of the closing layer followed by phellem cell generation and maturation. Collectively, the genes monitored were wound-inducible and their expression profiles markedly coordinated with closing layer formation and the index for phellogen layer meristematic activity during wound periderm development; results were more influenced by harvest than genotype. Importantly, StTLRP was the only gene examined that may be involved in phellogen cell wall thickening after cessation of phellogen cell division. Published by Elsevier GmbH.

Root Hairs

PubMed Central

Grierson, Claire; Nielsen, Erik; Ketelaarc, Tijs; Schiefelbein, John

2014-01-01

Roots hairs are cylindrical extensions of root epidermal cells that are important for acquisition of nutrients, microbe interactions, and plant anchorage. The molecular mechanisms involved in the specification, differentiation, and physiology of root hairs in Arabidopsis are reviewed here. Root hair specification in Arabidopsis is determined by position-dependent signaling and molecular feedback loops causing differential accumulation of a WD-bHLH-Myb transcriptional complex. The initiation of root hairs is dependent on the RHD6 bHLH gene family and auxin to define the site of outgrowth. Root hair elongation relies on polarized cell expansion at the growing tip, which involves multiple integrated processes including cell secretion, endomembrane trafficking, cytoskeletal organization, and cell wall modifications. The study of root hair biology in Arabidopsis has provided a model cell type for insights into many aspects of plant development and cell biology. PMID:24982600

Covisualization in living onion cells of putative integrin, putative spectrin, actin, putative intermediate filaments, and other proteins at the cell membrane and in an endomembrane sheath

NASA Technical Reports Server (NTRS)

Reuzeau, C.; Doolittle, K. W.; McNally, J. G.; Pickard, B. G.; Evans, M. L. (Principal Investigator)

1997-01-01

Covisualizations with wide-field computational optical-sectioning microscopy of living epidermal cells of the onion bulb scale have evidenced two major new cellular features. First, a sheath of cytoskeletal elements clads the endomembrane system. Similar elements clad the inner faces of punctate plasmalemmal sites interpreted as plasmalemmal control centers. One component of the endomembrane sheath and plasmalemmal control center cladding is anti-genicity-recognized by two injected antibodies against animal spectrin. Immunoblots of separated epidermal protein also showed bands recognized by these antibodies. Injected phalloidin identified F-actin with the same cellular distribution pattern, as did antibodies against intermediate-filament protein and other cytoskeletal elements known from animal cells. Injection of general protein stains demonstrated the abundance of endomembrane sheath protein. Second, the endomembrane system, like the plasmalemmal puncta, contains antigen recognized by an anti-beta 1 integrin injected into the cytoplasm. Previously, immunoblots of separated epidermal protein were shown to have a major band recognized both by this antibody prepared against a peptide representing the cytosolic region of beta 1 integrin and an antibody against the matrix region of beta 1 integrin. The latter antiboby also identified puncta at the external face of protoplasts. It is proposed that integrin and associated transmembrane proteins secure the endomembrane sheath and transmit signals between it and the lumen or matrix of the endoplasmic reticulum and organellar matrices. This function is comparable to that proposed for such transmembrane linkers in the plasmalemmal control centers, which also appear to bind cytoskeleton and a host of related molecules and transmit signals between them and the wall matrix. It is at the plasmalemmal control centers that the endoplasmic reticulum, a major component of the endomembrane system, attaches to the plasma membrane.

Overexpression of cyclin D1 induces the reprogramming of differentiated epidermal cells into stem cell-like cells.

PubMed

Zhao, Along; Yang, Leilei; Ma, Kui; Sun, Mengli; Li, Lei; Huang, Jin; Li, Yang; Zhang, Cuiping; Li, Haihong; Fu, Xiaobing

2016-01-01

It has been reported that Wnt/β-catenin is critical for dedifferentiation of differentiated epidermal cells. Cyclin D1 (CCND1) is a β-catenin target gene. In this study, we provide evidence that overexpression of CCND1 induces reprogramming of epidermal cells into stem cell-like cells. After introducing CCND1 gene into differentiated epidermal cells, we found that the large flat-shaped cells with a small nuclear-cytoplasmic ratio changed into small round-shaped cells with a large nuclear-cytoplasmic ratio. The expressions of CK10, β1-integrin, Oct4 and Nanog in CCND1 induced cells were remarkably higher than those in the control group (P < 0.01). In addition, the induced cells exhibited a high colony-forming ability and a long-term proliferative potential. When the induced cells were implanted into a wound of laboratory animal model, the wound healing was accelerated. These results suggested that overexpression of CCND1 induced the reprogramming of differentiated epidermal cells into stem cell-like cells. This study may also offer a new approach to yield epidermal stem cells for wound repair and regeneration.

Effects of heparin-binding epidermal growth factor-like growth factor on cell repopulation and signal transduction in periodontal ligament cells after scratch wounding in vitro.

PubMed

Lee, J S; Kim, J M; Hong, E K; Kim, S-O; Yoo, Y-J; Cha, J-H

2009-02-01

A growing amount of attention has been placed on periodontal regeneration and wound healing for periodontal therapy. This study was conducted in an effort to determine the effects of heparin-binding epidermal growth factor-like growth factor on cell repopulation and signal transduction in periodontal ligament cells after scratch wounding in vitro. Human periodontal ligament cells were acquired from explant tissue of human healthy periodontal ligament. After the wounding of periodontal ligament cells, the change in expression of heparin-binding epidermal growth factor-like growth factor and epidermal growth factor receptors 1-4 mRNA was assessed. The effects of heparin-binding epidermal growth factor-like growth factor on periodontal ligament cell proliferation and repopulation were assessed in vitro via the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and by photographing the injuries, respectively. Extracellular signal-regulated kinase (Erk)1/2, p38 and Akt phosphorylation was characterized via western blotting. Scratch wounding resulted in a significant up-regulation of heparin-binding epidermal growth factor-like growth factor mRNA expression, whereas wounding had no effect on the expression levels of epidermal growth factor receptors 1-4. Interestingly, no expression of epidermal growth factor receptors 2 and 4 was detectable prior to or after wounding. Heparin-binding epidermal growth factor-like growth factor treatment promoted the proliferation and repopulation of periodontal ligament cells. The scratch wounding also stimulated the phosphorylation of Erk1/2 and p38, but not of Akt, in periodontal ligament cells, and heparin-binding epidermal growth factor-like growth factor treatment applied after wounding amplified and extended the activations of Erk1/2 and p38, but not of Akt. Furthermore, Erk1/2 inhibition blocked the process of cell repopulation induced by heparin-binding epidermal growth factor-like growth factor, whereas the inhibition of p38 delayed the process. These results indicate that heparin-binding epidermal growth factor-like growth factor may constitute a critical factor in the wound healing of human periodontal ligament cells by a mechanism that requires the activation of Erk1/2 via specific interaction with epidermal growth factor receptor 1.

Vascularization, High-Volume Solution Flow, and Localized Roles for Enzymes of Sucrose Metabolism during Tumorigenesis by Agrobacterium tumefaciens1

PubMed Central

Wächter, Rebecca; Langhans, Markus; Aloni, Roni; Götz, Simone; Weilmünster, Anke; Koops, Ariane; Temguia, Leopoldine; Mistrik, Igor; Pavlovkin, Jan; Rascher, Uwe; Schwalm, Katja; Koch, Karen E.; Ullrich, Cornelia I.

2003-01-01

Vascular differentiation and epidermal disruption are associated with establishment of tumors induced by Agrobacterium tumefaciens. Here, we address the relationship of these processes to the redirection of nutrient-bearing water flow and carbohydrate delivery for tumor growth within the castor bean (Ricinus communis) host. Treatment with aminoethoxyvinyl-glycine showed that vascular differentiation and epidermal disruption were central to ethylene-dependent tumor establishment. CO2 release paralleled tumor growth, but water flow increased dramatically during the first 3 weeks. However, tumor water loss contributed little to water flow to host shoots. Tumor water loss was followed by accumulation of the osmoprotectants, sucrose (Suc) and proline, in the tumor periphery, shifting hexose-to-Suc balance in favor of sugar signals for maturation and desiccation tolerance. Concurrent activities and sites of action for enzymes of Suc metabolism changed: Vacuolar invertase predominated during initial import of Suc into the symplastic continuum, corresponding to hexose concentrations in expanding tumors. Later, Suc synthase (SuSy) and cell wall invertase rose in the tumor periphery to modulate both Suc accumulation and descending turgor for import by metabolization. Sites of abscisic acid immunolocalization correlated with both central vacuolar invertase and peripheral cell wall invertase. Vascular roles were indicated by SuSy immunolocalization in xylem parenchyma for inorganic nutrient uptake and in phloem, where resolution allowed SuSy identification in sieve elements and companion cells, which has widespread implications for SuSy function in transport. Together, data indicate key roles for ethylene-dependent vascularization and cuticular disruption in the redirection of water flow and carbohydrate transport for successful tumor establishment. PMID:14526106

Developmental patterning of the sub-epidermal integument cell layer in Arabidopsis seeds

PubMed Central

Coen, Olivier; Fiume, Elisa; Xu, Wenjia; De Vos, Delphine; Lu, Jing; Pechoux, Christine; Lepiniec, Loïc

2017-01-01

Angiosperm seed development is a paradigm of tissue cross-talk. Proper seed formation requires spatial and temporal coordination of the fertilization products – embryo and endosperm – and the surrounding seed coat maternal tissue. In early Arabidopsis seed development, all seed integuments were thought to respond homogenously to endosperm growth. Here, we show that the sub-epidermal integument cell layer has a unique developmental program. We characterized the cell patterning of the sub-epidermal integument cell layer, which initiates a previously uncharacterized extra cell layer, and identified TRANSPARENT TESTA 16 and SEEDSTICK MADS box transcription factors as master regulators of its polar development and cell architecture. Our data indicate that the differentiation of the sub-epidermal integument cell layer is insensitive to endosperm growth alone and to the repressive mechanism established by FERTILIZATION INDEPENDENT ENDOSPERM and MULTICOPY SUPPRESSOR OF IRA1 Polycomb group proteins. This work demonstrates the different responses of epidermal and sub-epidermal integument cell layers to fertilization. PMID:28348169

Why plants make puzzle cells, and how their shape emerges.

PubMed

Sapala, Aleksandra; Runions, Adam; Routier-Kierzkowska, Anne-Lise; Das Gupta, Mainak; Hong, Lilan; Hofhuis, Hugo; Verger, Stéphane; Mosca, Gabriella; Li, Chun-Biu; Hay, Angela; Hamant, Olivier; Roeder, Adrienne Hk; Tsiantis, Miltos; Prusinkiewicz, Przemyslaw; Smith, Richard S

2018-02-27

The shape and function of plant cells are often highly interdependent. The puzzle-shaped cells that appear in the epidermis of many plants are a striking example of a complex cell shape, however their functional benefit has remained elusive. We propose that these intricate forms provide an effective strategy to reduce mechanical stress in the cell wall of the epidermis. When tissue-level growth is isotropic, we hypothesize that lobes emerge at the cellular level to prevent formation of large isodiametric cells that would bulge under the stress produced by turgor pressure. Data from various plant organs and species support the relationship between lobes and growth isotropy, which we test with mutants where growth direction is perturbed. Using simulation models we show that a mechanism actively regulating cellular stress plausibly reproduces the development of epidermal cell shape. Together, our results suggest that mechanical stress is a key driver of cell-shape morphogenesis. © 2018, Sapala et al.

Why plants make puzzle cells, and how their shape emerges

PubMed Central

Routier-Kierzkowska, Anne-Lise; Das Gupta, Mainak; Hong, Lilan; Hofhuis, Hugo; Verger, Stéphane; Mosca, Gabriella; Li, Chun-Biu; Hay, Angela; Hamant, Olivier; Roeder, Adrienne HK; Tsiantis, Miltos; Prusinkiewicz, Przemyslaw

2018-01-01

The shape and function of plant cells are often highly interdependent. The puzzle-shaped cells that appear in the epidermis of many plants are a striking example of a complex cell shape, however their functional benefit has remained elusive. We propose that these intricate forms provide an effective strategy to reduce mechanical stress in the cell wall of the epidermis. When tissue-level growth is isotropic, we hypothesize that lobes emerge at the cellular level to prevent formation of large isodiametric cells that would bulge under the stress produced by turgor pressure. Data from various plant organs and species support the relationship between lobes and growth isotropy, which we test with mutants where growth direction is perturbed. Using simulation models we show that a mechanism actively regulating cellular stress plausibly reproduces the development of epidermal cell shape. Together, our results suggest that mechanical stress is a key driver of cell-shape morphogenesis. PMID:29482719

Ectopic Expression of Capsicum-Specific Cell Wall Protein Capsicum annuum Senescence-Delaying 1 (CaSD1) Delays Senescence and Induces Trichome Formation in Nicotiana benthamiana

PubMed Central

Seo, Eunyoung; Yeom, Seon-In; Jo, SungHwan; Jeong, Heejin; Kang, Byoung-Cheorl; Choi, Doil

2012-01-01

Secreted proteins are known to have multiple roles in plant development, metabolism, and stress response. In a previous study to understand the roles of secreted proteins, Capsicum annuum secreted proteins (CaS) were isolated by yeast secretion trap. Among the secreted proteins, we further characterized Capsicum annuum senescence-delaying 1 (CaSD1), a gene encoding a novel secreted protein that is present only in the genus Capsicum. The deduced CaSD1 contains multiple repeats of the amino acid sequence KPPIHNHKPTDYDRS. Interestingly, the number of repeats varied among cultivars and species in the Capsicum genus. CaSD1 is constitutively expressed in roots, and Agrobacterium-mediated transient overexpression of CaSD1 in Nicotiana benthamiana leaves resulted in delayed senescence with a dramatically increased number of trichomes and enlarged epidermal cells. Furthermore, senescence- and cell division-related genes were differentially regulated by CaSD1-overexpressing plants. These observations imply that the pepper-specific cell wall protein CaSD1 plays roles in plant growth and development by regulating cell division and differentiation. PMID:22441673

Immunocytochemical analysis of the subcellular distribution of ferritin in Imperata cylindrica (L.) Raeuschel, an iron hyperaccumulator plant.

PubMed

de la Fuente, Vicenta; Rodríguez, Nuria; Amils, Ricardo

2012-05-01

Ferritin is of interest at the structural and functional level not only as storage for iron, a critical element, but also as a means to prevent cell damage produced by oxidative stress. The main objective of this work was to confirm by immunocytochemistry the presence and the subcellular distribution of the ferritin detected by Mösbauer spectroscopy in Imperata cylindrica, a plant which accumulates large amounts of iron. The localization of ferritin was performed in epidermal, parenchymal and vascular tissues of shoots and leaves of I. cylindrica. The highest density of immunolabeling in shoots appeared in the intracellular space of cell tissues, near the cell walls and in the cytoplasm. In leaves, ferritin was detected in the proximity of the dense network of the middle lamella of cell walls, following a similar path to that observed in shoots. Immunolabeling was also localized in chloroplasts. The abundance of immunogold labelling in mitochondria for I. cylindrica was rather low, probably because the study dealt with tissues from old plants. These results further expand the localization of ferritin in cell components other than chloroplasts and mitochondria in plants. Copyright © 2011 Elsevier GmbH. All rights reserved.

Relationship between Endopolyploidy and Cell Size in Epidermal Tissue of Arabidopsis.

PubMed Central

Melaragno, JE; Mehrotra, B; Coleman, AW

1993-01-01

Relative quantities of DNA in individual nuclei of stem and leaf epidermal cells of Arabidopsis were measured microspectrofluorometrically using epidermal peels. The relative ploidy level in each nucleus was assessed by comparison to root tip mitotic nuclei. A clear pattern of regular endopolyploidy is evident in epidermal cells. Guard cell nuclei contain levels of DNA comparable to dividing root cells, the 2C level (i.e., one unreplicated copy of the nuclear DNA). Leaf trichome nuclei had elevated ploidy levels of 4C, 8C, 16C, 32C, and 64C, and their cytology suggested that the polyploidy represents a form of polyteny. The nuclei of epidermal pavement cells were 2C, 4C, and 8C in stem epidermis, and 2C, 4C, 8C, and 16C in leaf epidermis. Morphometry of epidermal pavement cells revealed a direct proportionality between nuclear DNA level and cell size. A consideration of the development process suggests that the cells of highest ploidy level are developmentally oldest; consequently, the developmental pattern of epidermal tissues can be read from the ploidy pattern of the cells. This observation is relevant to theories of stomate spacing and offers opportunities for genetic analysis of the endopolyploidy/polyteny phenomenon. PMID:12271050

Extracellular Matrix as a Regulator of Epidermal Stem Cell Fate.

PubMed

Chermnykh, Elina; Kalabusheva, Ekaterina; Vorotelyak, Ekaterina

2018-03-27

Epidermal stem cells reside within the specific anatomic location, called niche, which is a microenvironment that interacts with stem cells to regulate their fate. Regulation of many important processes, including maintenance of stem cell quiescence, self-renewal, and homeostasis, as well as the regulation of division and differentiation, are common functions of the stem cell niche. As it was shown in multiple studies, extracellular matrix (ECM) contributes a lot to stem cell niches in various tissues, including that of skin. In epidermis, ECM is represented, primarily, by a highly specialized ECM structure, basement membrane (BM), which separates the epidermal and dermal compartments. Epidermal stem cells contact with BM, but when they lose the contact and migrate to the overlying layers, they undergo terminal differentiation. When considering all of these factors, ECM is of fundamental importance in regulating epidermal stem cells maintenance, proper mobilization, and differentiation. Here, we summarize the remarkable progress that has recently been made in the research of ECM role in regulating epidermal stem cell fate, paying special attention to the hair follicle stem cell niche. We show that the destruction of ECM components impairs epidermal stem cell morphogenesis and homeostasis. A deep understanding of ECM molecular structure as well as the development of in vitro system for stem cell maintaining by ECM proteins may bring us to developing new approaches for regenerative medicine.

Gloss, colour and grip: multifunctional epidermal cell shapes in bee- and bird-pollinated flowers.

PubMed

Papiorek, Sarah; Junker, Robert R; Lunau, Klaus

2014-01-01

Flowers bear the function of filters supporting the attraction of pollinators as well as the deterrence of floral antagonists. The effect of epidermal cell shape on the visual display and tactile properties of flowers has been evaluated only recently. In this study we quantitatively measured epidermal cell shape, gloss and spectral reflectance of flowers pollinated by either bees or birds testing three hypotheses: The first two hypotheses imply that bee-pollinated flowers might benefit from rough surfaces on visually-active parts produced by conical epidermal cells, as they may enhance the colour signal of flowers as well as the grip on flowers for bees. In contrast, bird-pollinated flowers might benefit from flat surfaces produced by flat epidermal cells, by avoiding frequent visitation from non-pollinating bees due to a reduced colour signal, as birds do not rely on specific colour parameters while foraging. Moreover, flat petal surfaces in bird-pollinated flowers may hamper grip for bees that do not touch anthers and stigmas while consuming nectar and thus, are considered as nectar thieves. Beside this, the third hypothesis implies that those flower parts which are vulnerable to nectar robbing of bee- as well as bird-pollinated flowers benefit from flat epidermal cells, hampering grip for nectar robbing bees. Our comparative data show in fact that conical epidermal cells are restricted to visually-active parts of bee-pollinated flowers, whereas robbing-sensitive parts of bee-pollinated as well as the entire floral surface of bird-pollinated flowers possess on average flat epidermal cells. However, direct correlations between epidermal cell shape and colour parameters have not been found. Our results together with published experimental studies show that epidermal cell shape as a largely neglected flower trait might act as an important feature in pollinator attraction and avoidance of antagonists, and thus may contribute to the partitioning of flower-visitors.

The organization of human epidermis: functional epidermal units and phi proportionality.

PubMed

Hoath, Steven B; Leahy, D G

2003-12-01

The concept that mammalian epidermis is structurally organized into functional epidermal units has been proposed on the basis of stratum corneum (SC) architecture, proliferation kinetics, melanocyte:keratinocyte ratios (1:36), and, more recently, Langerhans cell: epidermal cell ratios (1:53). This article examines the concept of functional epidermal units in human skin in which the maintenance of phi (1.618034) proportionality provides a central organizing principle. The following empirical measurements were used: 75,346 nucleated epidermal cells per mm2, 1394 Langerhans cells per mm2, 1999 melanocytes per mm2, 16 (SC) layers, 900-microm2 corneocyte surface area, 17,778 corneocytes per mm2, 14-d (SC) turnover time, and 93,124 per mm2 total epidermal cells. Given these empirical data: (1) the number of corneocytes is a mean proportional between the sum of the Langerhans cell + melanocyte populations and the number of epidermal cells, 3393/17,778-17,778/93,124; (2) the ratio of nucleated epidermal cells over corneocytes is phi proportional, 75,346/17,778 approximately phi3; (3) assuming similar 14-d turnover times for the (SC) and Malpighian epidermis, the number of corneocytes results from subtraction of a cellular fraction equal to approximately 2/phi2 x the number of living cells, 75,436 - (2/phi2 x 75,346) approximately 17,778; and (4) if total epidermal turnover time equals (SC) turnover time x the ratio of living/dead cells, then compartmental turnover times are unequal (14 d for (SC) to 45.3 d for nucleated epidermis approximately 1/2phi) and cellular replacement rates are 52.9 corneocytes/69.3 keratinocytes per mm2 per h approximately 2/phi2. These empirically derived equivalences provide logicomathematical support for the presence of functional epidermal units in human skin. Validation of a phi proportional unit architecture in human epidermis will be important for tissue engineering of skin and the design of instruments for skin measurement.

Hornwort Stomata: Architecture and Fate Shared with 400-Million-Year-Old Fossil Plants without Leaves.

PubMed

Renzaglia, Karen S; Villarreal, Juan Carlos; Piatkowski, Bryan T; Lucas, Jessica R; Merced, Amelia

2017-06-01

As one of the earliest plant groups to evolve stomata, hornworts are key to understanding the origin and function of stomata. Hornwort stomata are large and scattered on sporangia that grow from their bases and release spores at their tips. We present data from development and immunocytochemistry that identify a role for hornwort stomata that is correlated with sporangial and spore maturation. We measured guard cells across the genera with stomata to assess developmental changes in size and to analyze any correlation with genome size. Stomata form at the base of the sporophyte in the green region, where they develop differential wall thickenings, form a pore, and die. Guard cells collapse inwardly, increase in surface area, and remain perched over a substomatal cavity and network of intercellular spaces that is initially fluid filled. Following pore formation, the sporophyte dries from the outside inwardly and continues to do so after guard cells die and collapse. Spore tetrads develop in spore mother cell walls within a mucilaginous matrix, both of which progressively dry before sporophyte dehiscence. A lack of correlation between guard cell size and DNA content, lack of arabinans in cell walls, and perpetually open pores are consistent with the inactivity of hornwort stomata. Stomata are expendable in hornworts, as they have been lost twice in derived taxa. Guard cells and epidermal cells of hornworts show striking similarities with the earliest plant fossils. Our findings identify an architecture and fate of stomata in hornworts that is ancient and common to plants without sporophytic leaves. © 2017 American Society of Plant Biologists. All Rights Reserved.

Mechanosensory calcium-selective cation channels in epidermal cells

NASA Technical Reports Server (NTRS)

Ding, J. P.; Pickard, B. G.

1993-01-01

This paper explores the properties and likely functions of an epidermal Ca(2+)-selective cation channel complex activated by tension. As many as eight or nine linked or linkable equivalent conductance units or co-channels can open together. Open time for co-channel quadruplets and quintuplets tends to be relatively long with millimolar Mg2+ (but not millimolar Ca2+) at the cytosolic face of excised plasma membrane. Sensitivity to tension is regulated by transmembrane voltage and temperature. Under some circumstances channel activity is sychronized in rhythmic pulses. Certain lanthanides and a cytoskeleton-disturbing herbicide that inhibit gravitropic reception act on the channel system at low concentrations. Specifically, ethyl-N-phenylcarbamate promotes tension-dependent activity at micromolar levels. With moderate suction, Gd3+ provided at about 0.5 micromole at the extracellular face of the membrane promotes for several seconds but may then become inhibitory. Provision at 1-2 micromoles promotes and subsequently inhibits more vigorously (often abruptly and totally), and at high levels inhibits immediately. La3+, a poor gravitropic inhibitor, acts similarly but much more gradually and only at much higher concentrations. These properties, particularly these susceptibilities to modulation, indicate that in vivo the mechanosensitive channel must be mechanosensory and mechanoregulatory. It could serve to transduce the shear forces generated in the integrated wall-membrane-cytoskeleton system during turgor changes and cell expansion as well as transducing the stresses induced by gravity, touch and flexure. In so far as such transduction is modulated by voltage and temperature, the channels would also be sensors for these modalities as long as the wall-membrane-cytoskeleton system experiences mechanical stress.

21 CFR 358.703 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-04-01

... increased rate of shedding of dead epidermal cells of the scalp. (c) Psoriasis. A condition of the scalp or body characterized by irritation, itching, redness, and extreme excess shedding of dead epidermal cells..., redness, and excess shedding of dead epidermal cells. (e) Selenium sulfide, micronized. Selenium sulfide...

21 CFR 358.703 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-04-01

... increased rate of shedding of dead epidermal cells of the scalp. (c) Psoriasis. A condition of the scalp or body characterized by irritation, itching, redness, and extreme excess shedding of dead epidermal cells..., redness, and excess shedding of dead epidermal cells. (e) Selenium sulfide, micronized. Selenium sulfide...

21 CFR 358.703 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-04-01

... increased rate of shedding of dead epidermal cells of the scalp. (c) Psoriasis. A condition of the scalp or body characterized by irritation, itching, redness, and extreme excess shedding of dead epidermal cells..., redness, and excess shedding of dead epidermal cells. (e) Selenium sulfide, micronized. Selenium sulfide...

21 CFR 358.703 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-04-01

... increased rate of shedding of dead epidermal cells of the scalp. (c) Psoriasis. A condition of the scalp or body characterized by irritation, itching, redness, and extreme excess shedding of dead epidermal cells..., redness, and excess shedding of dead epidermal cells. (e) Selenium sulfide, micronized. Selenium sulfide...

21 CFR 358.703 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-04-01

... increased rate of shedding of dead epidermal cells of the scalp. (c) Psoriasis. A condition of the scalp or body characterized by irritation, itching, redness, and extreme excess shedding of dead epidermal cells..., redness, and excess shedding of dead epidermal cells. (e) Selenium sulfide, micronized. Selenium sulfide...

Gravitropism of axial organs in multicellular plants

NASA Astrophysics Data System (ADS)

Kutschera, U.

Gravitropism of plant organs such as roots, stems and coleoptiles can be separated into four distinct phases: 1. perception (gravity sensing), 2. transduction of a signal into the target region and 3. the response (differential growth). This last reaction is followed by a straightening of the curved organ (4.). The perception of the gravitropic stimulus upon horizontal positioning of the organ (1.) occurs via amyloplasts that sediment within the statocytes. This conclusion is supported by our finding that submerged rice coleoptiles that lack sedimentable amyloplasts show no graviresponse. The mode of signal transduction (2.) from the statocytes to the peripheral cell layers is still unknown. Differential growth (3.) consists of a cessation of cell expansion on the upper side and an enhancement of elongation on the lower side of the organ. Based on the facts that the sturdy outer epidermal wall (OEW) constitutes the growth-controlling structure of the coleoptile and that growth-related osmiophilic particles accumulate on the upper OEW, it is concluded that the differential incorporation of wall material (presumably glycoproteins) is causally involved. During gravitropic bending, electron-dense particles ('wall-loosening capacity') accumulate on the growth-inhibited upper OEW. It is proposed that the autotropic straightening response, which is in part due to an acceleration of cell elongation on the curved upper side, may be attributable to an incorporation of the accumulated particles ('release of wall-loosening capacity'). This novel mechanism of autotropic re-bending and its implications for the Cholodny-Went hypothesis are discussed.

Stylostome formation in trombiculid mites (Acariformes: Trombiculidae).

PubMed

Shatrov, Andrew B

2009-12-01

Stylostomes of the trombiculid mite larvae Neotrombicula pomeranzevi (Schluger), Hirsutiella zachvatkini (Schluger), Miyatrombicula esoensis (Sasa and Ogata) and Euschoengastia rotundata (Schluger) (Acariformes: Trombiculidae), formed in the host skin during feeding of the parasites on their natural hosts (voles) were studied histologically and histochemically. A stylostome is a variously shaped tube formed of solidified mite saliva that extends from the mouthparts of the parasite through the epidermis into the dermis of the host, and allows the mite to obtain its liquid food. The first step of stylostome formation is deposition of an eosinophilic cone, to which the larva's chelicerae are glued. Organization of the stylostome depends on the mite species, and its walls may show weakly expressed longitudinal or transverse stratification. Histochemically, the stylostome is composed of complex glycoprotein with varying tinctorial properties through the width or the length of the stylostome's walls. Beneath the distal end of the stylostome, irrespectively of its localization either in the epidermis or in the dermis of the host, a feeding cavity is formed as a result of the action of the hydrolytic components of the mite's saliva forced through the stylostome into the wound. An inflammatory dermal reaction of moderate intensity is evolved during larval feeding and stylostome formation. It is manifested by the infiltration of the foci with neutrophiles, lymphocytes and macrophages and by dilation of capillaries of the terminal vessel bed and filling them by erythrocytes and other blood elements. Around the stylostome, necrosis of the epidermal cells occurs, leucocytes come to the damaged area and fuse with the necrotic epidermal cells, leading to the formation of the large scabs on the surface of the host's skin. In the case of E. rotundata, single capsules having a terminal opening and containing feeding larva are formed on the abdomen of the hosts. The walls of the capsules are composed of the mite's saliva flowing upon the surface of the host's skin. At the bottom of the capsule, a stylostome perforating the epidermis is also present.

A bacterial-type ABC transporter is involved in aluminum tolerance in rice.

PubMed

Huang, Chao Feng; Yamaji, Naoki; Mitani, Namiki; Yano, Masahiro; Nagamura, Yoshiaki; Ma, Jian Feng

2009-02-01

Aluminum (Al) toxicity is a major factor limiting crop production in acidic soil, but the molecular mechanisms of Al tolerance are poorly understood. Here, we report that two genes, STAR1 (for sensitive to Al rhizotoxicity1) and STAR2, are responsible for Al tolerance in rice. STAR1 encodes a nucleotide binding domain, while STAR2 encodes a transmembrane domain, of a bacterial-type ATP binding cassette (ABC) transporter. Disruption of either gene resulted in hypersensitivity to aluminum toxicity. Both STAR1 and STAR2 are expressed mainly in the roots and are specifically induced by Al exposure. Expression in onion epidermal cells, rice protoplasts, and yeast showed that STAR1 interacts with STAR2 to form a complex that localizes to the vesicle membranes of all root cells, except for those in the epidermal layer of the mature zone. When expressed together in Xenopus laevis oocytes, STAR1/2 shows efflux transport activity specific for UDP-glucose. Furthermore, addition of exogenous UDP-glucose rescued root growth in the star1 mutant exposed to Al. These results indicate that STAR1 and STAR2 form a complex that functions as an ABC transporter, which is required for detoxification of Al in rice. The ABC transporter transports UDP-glucose, which may be used to modify the cell wall.

Successful pemetrexed-containing chemotherapy for epidermal growth factor receptor mutation-positive adenosquamous cell carcinoma of the lung: A case report

PubMed Central

WATANABE, HIROKO; TAMURA, TOMOHIRO; KAGOHASHI, KATSUNORI; KAWAGUCHI, MIO; KURISHIMA, KOICHI; SATOH, HIROAKI

2016-01-01

Pemetrexed-containing chemotherapy has shown promise in the treatment of non-small-cell lung cancer (NSCLC). However, although adenosquamous cell lung cancer (ASCLC) is a type of NSCLC, the availability of studies investigating its response to pemetrexed-containing chemotherapy is limited. A 66-year-old woman was referred to Mito Medical Center, University of Tsukuba with hemoptysis and a chest computed tomography (CT) scan revealed a large cavitary mass in the lower lobe of the left lung. The patient underwent left lower lobectomy and mediastinal lymph node dissection. The tumor was staged as pT2bN2M0. An epidermal growth factor receptor (EGFR) exon 19 deletion was identified in the adenocarcinomatous as well as the squamous cell carcinomatous components. Despite gefitinib therapy for pulmonary metastases, the patient developed cavitary metastases in both lungs. Therefore, treatment with pemetrexed-containing chemotherapy was initiated. A chest CT scan revealed significant regression of the metastatic lesions in both lungs, with thinning of the walls. The patient remains well and recurrence-free 19 months after the initiation of pemetrexed-containing chemotherapy. Therefore, the clinical response of EGFR mutation-positive ASCLC to pemetrexed-containing chemotherapy was promising, suggesting pemetrexed to be one of the key drugs for this subset of ASCLC patients. PMID:27073680

Psoriatic T cells reduce epidermal turnover time and affect cell proliferation contributed from differential gene expression.

PubMed

Li, Junqin; Li, Xinhua; Hou, Ruixia; Liu, Ruifeng; Zhao, Xincheng; Dong, Feng; Wang, Chunfang; Yin, Guohua; Zhang, Kaiming

2015-09-01

Psoriasis is mediated primarily by T cells, which reduce epidermal turnover time and affect keratinocyte proliferation. We aimed to identify differentially expressed genes (DEG) in T cells from normal, five pairs of monozygotic twins concordant or discordant for psoriasis, to determine whether these DEG may account for the influence to epidermal turnover time and keratinocyte proliferation. The impact of T cells on keratinocyte proliferation and epidermal turnover time were investigated separately by immunohistochemistry and cultured with (3) H-TdR. mRNA expression patterns were investigated by RNA sequencing and verified by real-time reverse transcription polymerase chain reaction. After co-culture with psoriatic T cells, the expression of Ki-67, c-Myc and p53 increased, while expression of Bcl-2 and epidermal turnover time decreased. There were 14 DEG which were found to participate in the regulation of cell proliferation or differentiation. Psoriatic T cells exhibited the ability to decrease epidermal turnover time and affect keratinocyte proliferation because of the differential expression of PPIL1, HSPH1, SENP3, NUP54, FABP5, PLEKHG3, SLC9A9 and CHCHD4. © 2015 Japanese Dermatological Association.

Multiplexed Five-Color Molecular Imaging of Cancer Cells and Tumor Tissues with Carbon Nanotube Raman Tags in the Near-Infrared

PubMed Central

Liu, Zhuang; Tabakman, Scott; Sherlock, Sarah; Li, Xiaolin; Chen, Zhuo; Jiang, Kaili; Fan, Shoushan; Dai, Hongjie

2011-01-01

Single-walled carbon nanotubes (SWNTs) with five different C13/C12 isotope compositions and well-separated Raman peaks have been synthesized and conjugated to five targeting ligands in order to impart molecular specificity. Multiplexed Raman imaging of live cells has been carried out by highly specific staining of cells with a five-color mixture of SWNTs. Ex vivo multiplexed Raman imaging of tumor samples uncovers a surprising up-regulation of epidermal growth factor receptor (EGFR) on LS174T colon cancer cells from cell culture to in vivo tumor growth. This is the first time five-color multiplexed molecular imaging has been performed in the near-infrared (NIR) region under a single laser excitation. Near zero interfering background of imaging is achieved due to the sharp Raman peaks unique to nanotubes over the low, smooth autofluorescence background of biological species. PMID:21442006

A STUDY OF THE COMPONENTS OF THE CORNIFIED EPITHELIUM OF HUMAN SKIN

PubMed Central

Matoltsy, A. Gedeon; Balsamo, Constance A.

1955-01-01

Pulverized cornified epithelium of human skin was divided into a "soluble fraction" and a "residue." About half of the "soluble fraction" proved to be soluble epidermal keratin (keratin A); the remainder, dialyzable substances of low molecular weight. The "residue" contained epidermal keratin and resistant cell membranes of cornified cells. Epidermal keratin was found to form an oriented and dense submicroscopic structure in the cornified cells. It showed high resistance toward strong acid and moderately strong alkali solutions as well as concentrated urea. In strong alkali, reducing substances, alkaline urea, and mixtures of reducing substance with alkali, epidermal keratin dissociated and yielded a non-dialyzable derivative of high molecular weight (keratin B) which resembled true proteins. The cell membranes of cornified cells showed higher resistance toward strong alkali and reducing substance than did epidermal keratin. PMID:13242598

Plasma Membrane Ca2+-Permeable Channels are Differentially Regulated by Ethylene and Hydrogen Peroxide to Generate Persistent Plumes of Elevated Cytosolic Ca2+ During Transfer Cell Trans-Differentiation.

PubMed

Zhang, Hui-ming; van Helden, Dirk F; McCurdy, David W; Offler, Christina E; Patrick, John W

2015-09-01

The enhanced transport capability of transfer cells (TCs) arises from their ingrowth wall architecture comprised of a uniform wall on which wall ingrowths are deposited. The wall ingrowth papillae provide scaffolds to amplify plasma membranes that are enriched in nutrient transporters. Using Vicia faba cotyledons, whose adaxial epidermal cells spontaneously and rapidly (hours) undergo a synchronous TC trans-differentiation upon transfer to culture, has led to the discovery of a cascade of inductive signals orchestrating deposition of ingrowth wall papillae. Auxin-induced ethylene biosynthesis initiates the cascade. This in turn drives a burst in extracellular H2O2 production that triggers uniform wall deposition. Thereafter, a persistent and elevated cytosolic Ca(2+) concentration, resulting from Ca(2+) influx through plasma membrane Ca(2+)-permeable channels, generates a Ca(2+) signal that directs formation of wall ingrowth papillae to specific loci. We now report how these Ca(2+)-permeable channels are regulated using the proportionate responses in cytosolic Ca(2+) concentration as a proxy measure of their transport activity. Culturing cotyledons on various combinations of pharmacological agents allowed the regulatory influence of each upstream signal on Ca(2+) channel activity to be evaluated. The findings demonstrated that Ca(2+)-permeable channel activity was insensitive to auxin, but up-regulated by ethylene through two independent routes. In one route ethylene acts directly on Ca(2+)-permeable channel activity at the transcriptional and post-translational levels, through an ethylene receptor-dependent pathway. The other route is mediated by an ethylene-induced production of extracellular H2O2 which then acts translationally and post-translationally to up-regulate Ca(2+)-permeable channel activity. A model describing the differential regulation of Ca(2+)-permeable channel activity is presented. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Transport barriers made of cutin, suberin and associated waxes.

PubMed

Schreiber, Lukas

2010-10-01

Cutinized leaf epidermal cells and suberized root cell walls form important lipophilic interfaces between the plant and its environment, significantly contributing to the regulation of water uptake and the transport of solutes in and out of the plant. A wealth of new molecular information on the genes and enzymes contributing to cutin, suberin and wax biosynthesis have become available within the past few years, which is examined in the context of the functional properties of these barriers in terms of transport and permeability. Recent progress made in measuring transport properties of cutinized and suberized barriers in plants is reviewed, and promising approaches obtained with Arabidopsis and potato that might link the molecular information with transport properties are suggested. Copyright © 2010 Elsevier Ltd. All rights reserved.

Difference in light-induced increase in ploidy level and cell size between adaxial and abaxial epidermal pavement cells of Phaseolus vulgaris primary leaves.

PubMed

Kinoshita, Isao; Sanbe, Akiko; Yokomura, E-iti

2008-01-01

Changes in nuclear DNA content and cell size of adaxial and abaxial epidermal pavement cells were investigated using bright light-induced leaf expansion of Phaseolus vulgaris plants. In primary leaves of bean plants grown under high (sunlight) or moderate (ML; photon flux density, 163 micromol m(-2) s(-1)) light, most adaxial epidermal pavement cells had a nucleus with the 4C amount of DNA, whereas most abaxial pavement cells had a 2C nucleus. In contrast, plants grown under low intensity white light (LL; 15 micromol m(-2) s(-1)) for 13 d, when cell proliferation of epidermal pavement cells had already finished, had a 2C nuclear DNA content in most adaxial pavement cells. When these LL-grown plants were transferred to ML, the increase in irradiance raised the frequency of 4C nuclei in adaxial but not in abaxial pavement cells within 4 d. On the other hand, the size of abaxial pavement cells increased by 53% within 4 d of transfer to ML and remained unchanged thereafter, whereas adaxial pavement cells continuously enlarged for 12 d. This suggests that the increase in adaxial cell size after 4 d is supported by the nuclear DNA doubling. The different responses between adaxial and abaxial epidermal cells were not induced by the different light intensity at both surfaces. It was shown that adaxial epidermal cells have a different property than abaxial ones.

Heterotrimeric G Protein Signaling Is Required for Epidermal Cell Death in Rice[W][OA

PubMed Central

Steffens, Bianka; Sauter, Margret

2009-01-01

In rice (Oryza sativa) adventitious root primordia are formed at the nodes as part of normal development. Upon submergence of rice plants, adventitious roots emerge from the nodes preceded by death of epidermal cells above the root primordia. Cell death is induced by ethylene and mediated by hydrogen peroxide (H2O2). Pharmacological experiments indicated that epidermal cell death was dependent on signaling through G proteins. Treatment with GTP-γ-S induced epidermal cell death, whereas GDP-β-S partially inhibited ethylene-induced cell death. The dwarf1 (d1) mutant of rice has repressed expression of the Gα subunit RGA1 of heterotrimeric G protein. In d1 plants, cell death in response to ethylene and H2O2 was nearly completely abolished, indicating that signaling through Gα is essential. Ethylene and H2O2 were previously shown to alter gene expression in epidermal cells that undergo cell death. Transcriptional regulation was not generally affected in the d1 mutant, indicating that altered gene expression is not sufficient to trigger cell death in the absence of Gα. Analysis of genes encoding proteins related to G protein signaling revealed that four small GTPase genes, two GTPase-activating protein genes, and one GDP dissociation inhibitor gene but not RGA1 were differentially expressed in epidermal cells above adventitious roots, indicating that Gα activity is regulated posttranscriptionally. PMID:19656904

Flying saucer1 is a transmembrane RING E3 ubiquitin ligase that regulates the degree of pectin methylesterification in Arabidopsis seed mucilage.

PubMed

Voiniciuc, Catalin; Dean, Gillian H; Griffiths, Jonathan S; Kirchsteiger, Kerstin; Hwang, Yeen Ting; Gillett, Alan; Dow, Graham; Western, Tamara L; Estelle, Mark; Haughn, George W

2013-03-01

Pectins are complex polysaccharides that form the gel matrix of the primary cell wall and are abundant in the middle lamella that holds plant cells together. Their degree of methylesterification (DM) impacts wall strength and cell adhesion since unesterified pectin regions can cross-link via Ca(2+) ions to form stronger gels. Here, we characterize flying saucer1 (fly1), a novel Arabidopsis thaliana seed coat mutant, which displays primary wall detachment, reduced mucilage extrusion, and increased mucilage adherence. These defects appear to result from a lower DM in mucilage and are enhanced by the addition of Ca(2+) or completely rescued using alkaline Ca(2+) chelators. FLY1 encodes a transmembrane protein with a RING-H2 domain that has in vitro E3 ubiquitin ligase activity. FLY1 is orthologous to TRANSMEMBRANE UBIQUITIN LIGASE1, a Golgi-localized E3 ligase involved in the quality control of membrane proteins in yeast. However, FLY1-yellow fluorescent protein (YFP) fusions are localized in punctae that are predominantly distinct from the Golgi and the trans-Golgi network/early endosome in the seed coat epidermis. Wortmannin treatment, which induces the fusion of late endosomes in plants, resulted in enlarged FLY1-YFP bodies. We propose that FLY1 regulates the DM of pectin in mucilage, potentially by recycling pectin methylesterase enzymes in the endomembrane system of seed coat epidermal cells.

FLYING SAUCER1 Is a Transmembrane RING E3 Ubiquitin Ligase That Regulates the Degree of Pectin Methylesterification in Arabidopsis Seed Mucilage[W

PubMed Central

Voiniciuc, Cătălin; Dean, Gillian H.; Griffiths, Jonathan S.; Kirchsteiger, Kerstin; Hwang, Yeen Ting; Gillett, Alan; Dow, Graham; Western, Tamara L.; Estelle, Mark; Haughn, George W.

2013-01-01

Pectins are complex polysaccharides that form the gel matrix of the primary cell wall and are abundant in the middle lamella that holds plant cells together. Their degree of methylesterification (DM) impacts wall strength and cell adhesion since unesterified pectin regions can cross-link via Ca2+ ions to form stronger gels. Here, we characterize flying saucer1 (fly1), a novel Arabidopsis thaliana seed coat mutant, which displays primary wall detachment, reduced mucilage extrusion, and increased mucilage adherence. These defects appear to result from a lower DM in mucilage and are enhanced by the addition of Ca2+ or completely rescued using alkaline Ca2+ chelators. FLY1 encodes a transmembrane protein with a RING-H2 domain that has in vitro E3 ubiquitin ligase activity. FLY1 is orthologous to TRANSMEMBRANE UBIQUITIN LIGASE1, a Golgi-localized E3 ligase involved in the quality control of membrane proteins in yeast. However, FLY1–yellow fluorescent protein (YFP) fusions are localized in punctae that are predominantly distinct from the Golgi and the trans-Golgi network/early endosome in the seed coat epidermis. Wortmannin treatment, which induces the fusion of late endosomes in plants, resulted in enlarged FLY1-YFP bodies. We propose that FLY1 regulates the DM of pectin in mucilage, potentially by recycling pectin methylesterase enzymes in the endomembrane system of seed coat epidermal cells. PMID:23482858

Oxide nanomembrane hybrids with enhanced mechano- and thermo-sensitivity for semitransparent epidermal electronics.

PubMed

Park, Minjoon; Do, Kyungsik; Kim, Jaemin; Son, Donghee; Koo, Ja Hoon; Park, Jinkyung; Song, Jun-Kyul; Kim, Ji Hoon; Lee, Minbaek; Hyeon, Taeghwan; Kim, Dae-Hyeong

2015-05-01

Oxide nanomembrane hybrids with enhanced mechano- and thermo-sensitivity for semitransparent epidermal electronics are developed. The use of nanomaterials (single wall nanotubes and silver nanoparticles) embedded in the oxide nanomembranes significantly enhances mechanical and thermal sensitivities. These mechanical and thermal sensors are utilized in wheelchair control and hypothermia detection, which are useful for patients with strokes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Epidermal Th22 and Tc17 cells form a localized disease memory in clinically healed psoriasis.

PubMed

Cheuk, Stanley; Wikén, Maria; Blomqvist, Lennart; Nylén, Susanne; Talme, Toomas; Ståhle, Mona; Eidsmo, Liv

2014-04-01

Psoriasis is a common and chronic inflammatory skin disease in which T cells play a key role. Effective treatment heals the skin without scarring, but typically psoriasis recurs in previously affected areas. A pathogenic memory within the skin has been proposed, but the nature of such site-specific disease memory is unknown. Tissue-resident memory T (TRM) cells have been ascribed a role in immunity after resolved viral skin infections. Because of their localization in the epidermal compartment of the skin, TRM may contribute to tissue pathology during psoriasis. In this study, we investigated whether resolved psoriasis lesions contain TRM cells with the ability to maintain and potentially drive recurrent disease. Three common and effective therapies, narrowband-UVB treatment and long-term biologic treatment systemically inhibiting TNF-α or IL-12/23 signaling were studied. Epidermal T cells were highly activated in psoriasis and a high proportion of CD8 T cells expressed TRM markers. In resolved psoriasis, a population of cutaneous lymphocyte-associated Ag, CCR6, CD103, and IL-23R expressing epidermal CD8 T cells was highly enriched. Epidermal CD8 T cells expressing the TRM marker CD103 responded to ex vivo stimulation with IL-17A production and epidermal CD4 T cells responded with IL-22 production after as long as 6 y of TNF-α inhibition. Our data suggest that epidermal TRM cells are retained in resolved psoriasis and that these cells are capable of producing cytokines with a critical role in psoriasis pathogenesis. We provide a potential mechanism for a site-specific T cell-driven disease memory in psoriasis.

The role of the SCRAMBLED receptor-like kinase in patterning the Arabidopsis root epidermis.

PubMed

Kwak, Su-Hwan; Schiefelbein, John

2007-02-01

Cell-type patterning in the Arabidopsis root epidermis is achieved by a network of transcription factors and influenced by a position-dependent mechanism. The SCRAMBLED receptor-like kinase is required for the normal pattern to arise, but its precise role is not understood. Here we describe genetic and molecular studies to define the spatial and temporal role of SCM in epidermal patterning and its relationship to the transcriptional network. Our results suggest that SCM helps unspecified epidermal cells interpret their position in relation to the underlying cortical cells and establish distinct cell identities. Furthermore, SCM loss-of-function and overexpression analyses suggest that SCM influences cell fate through its negative transcriptional regulation of the WEREWOLF MYB gene in epidermal cells at the H position. We also find that SCM function is specifically required for patterning the post-embryonic root epidermis and not for the analogous epidermal cell-type patterning during embryogenesis or hypocotyl development. In addition, we show that two closely related SCM-like genes in Arabidopsis (SRF1 and SRF3) are not required alone or together with SCM for proper epidermal patterning. These findings help define the developmental and mechanistic role of SCM and suggest a new model for its action in root epidermal cell patterning.

Serine Proteolytic Pathway Activation Reveals an Expanded Ensemble of Wound Response Genes in Drosophila

PubMed Central

Patterson, Rachel A.; Juarez, Michelle T.; Hermann, Anita; Sasik, Roman; Hardiman, Gary; McGinnis, William

2013-01-01

After injury to the animal epidermis, a variety of genes are transcriptionally activated in nearby cells to regenerate the missing cells and facilitate barrier repair. The range and types of diffusible wound signals that are produced by damaged epidermis and function to activate repair genes during epidermal regeneration remains a subject of very active study in many animals. In Drosophila embryos, we have discovered that serine protease function is locally activated around wound sites, and is also required for localized activation of epidermal repair genes. The serine protease trypsin is sufficient to induce a striking global epidermal wound response without inflicting cell death or compromising the integrity of the epithelial barrier. We developed a trypsin wounding treatment as an amplification tool to more fully understand the changes in the Drosophila transcriptome that occur after epidermal injury. By comparing our array results with similar results on mammalian skin wounding we can see which evolutionarily conserved pathways are activated after epidermal wounding in very diverse animals. Our innovative serine protease-mediated wounding protocol allowed us to identify 8 additional genes that are activated in epidermal cells in the immediate vicinity of puncture wounds, and the functions of many of these genes suggest novel genetic pathways that may control epidermal wound repair. Additionally, our data augments the evidence that clean puncture wounding can mount a powerful innate immune transcriptional response, with different innate immune genes being activated in an interesting variety of ways. These include puncture-induced activation only in epidermal cells in the immediate vicinity of wounds, or in all epidermal cells, or specifically in the fat body, or in multiple tissues. PMID:23637905

Exposure to Carbon Nanotube Material: Assessment of Nanotube Cytotoxicity Using Human Keratinocyte Cells

NASA Technical Reports Server (NTRS)

Shvedova, Anna A.; Castranova, Vincent; Kisin, Elena R.; Schwegler-Berry, Diane; Murray, Ashley R.; Gandelsman, Vadim Z.; Maynard, Andrew; Baron, Paul

2003-01-01

Carbon nanotubes are new members of carbon allotropes similar to fullerenes and graphite. Because of their unique electrical, mechanical, and thermal properties, carbon nanotubes are important for novel applications in the electronics, aerospace, and computer industries. Exposure to graphite and carbon materials has been associated with increased incidence of skin diseases, such as carbon fiber dermatitis, hyperkeratosis, and naevi. We investigated adverse effects of single-wall carbon nanotubes (SWCNT) using a cell culture of immortalized human epidermal keratinocytes (HaCaT). After 18 h of exposure of HaCaT to SWCNT, oxidative stress and cellular toxicity were indicated by formation of free radicals, accumulation of peroxidative products, antioxidant depletion, and loss of cell viability. Exposure to SWCNT also resulted in ultrastructural and morphological changes in cultured skin cells. These data indicate that dermal exposure to unrefined SWCNT may lead to dermal toxicity due to accelerated oxidative stress in the skin of exposed workers.

Active Sites of Reduced Epidermal Fluorescence1 (REF1) Isoforms Contain Amino Acid Substitutions That Are Different between Monocots and Dicots

PubMed Central

Missihoun, Tagnon D.; Kotchoni, Simeon O.; Bartels, Dorothea

2016-01-01

Plant aldehyde dehydrogenases (ALDHs) play important roles in cell wall biosynthesis, growth, development, and tolerance to biotic and abiotic stresses. The Reduced Epidermal Fluorescence1 is encoded by the subfamily 2C of ALDHs and was shown to oxidise coniferaldehyde and sinapaldehyde to ferulic acid and sinapic acid in the phenylpropanoid pathway, respectively. This knowledge has been gained from works in the dicotyledon model species Arabidopsis thaliana then used to functionally annotate ALDH2C isoforms in other species, based on the orthology principle. However, the extent to which the ALDH isoforms differ between monocotyledons and dicotyledons has rarely been accessed side-by-side. In this study, we used a phylogenetic approach to address this question. We have analysed the ALDH genes in Brachypodium distachyon, alongside those of other sequenced monocotyledon and dicotyledon species to examine traits supporting either a convergent or divergent evolution of the ALDH2C/REF1-type proteins. We found that B. distachyon, like other grasses, contains more ALDH2C/REF1 isoforms than A. thaliana and other dicotyledon species. Some amino acid residues in ALDH2C/REF1 isoforms were found as being conserved in dicotyledons but substituted by non-equivalent residues in monocotyledons. One example of those substitutions concerns a conserved phenylalanine and a conserved tyrosine in monocotyledons and dicotyledons, respectively. Protein structure modelling suggests that the presence of tyrosine would widen the substrate-binding pocket in the dicotyledons, and thereby influence substrate specificity. We discussed the importance of these findings as new hints to investigate why ferulic acid contents and cell wall digestibility differ between the dicotyledon and monocotyledon species. PMID:27798665

Active Sites of Reduced Epidermal Fluorescence1 (REF1) Isoforms Contain Amino Acid Substitutions That Are Different between Monocots and Dicots.

PubMed

Missihoun, Tagnon D; Kotchoni, Simeon O; Bartels, Dorothea

2016-01-01

Plant aldehyde dehydrogenases (ALDHs) play important roles in cell wall biosynthesis, growth, development, and tolerance to biotic and abiotic stresses. The Reduced Epidermal Fluorescence1 is encoded by the subfamily 2C of ALDHs and was shown to oxidise coniferaldehyde and sinapaldehyde to ferulic acid and sinapic acid in the phenylpropanoid pathway, respectively. This knowledge has been gained from works in the dicotyledon model species Arabidopsis thaliana then used to functionally annotate ALDH2C isoforms in other species, based on the orthology principle. However, the extent to which the ALDH isoforms differ between monocotyledons and dicotyledons has rarely been accessed side-by-side. In this study, we used a phylogenetic approach to address this question. We have analysed the ALDH genes in Brachypodium distachyon, alongside those of other sequenced monocotyledon and dicotyledon species to examine traits supporting either a convergent or divergent evolution of the ALDH2C/REF1-type proteins. We found that B. distachyon, like other grasses, contains more ALDH2C/REF1 isoforms than A. thaliana and other dicotyledon species. Some amino acid residues in ALDH2C/REF1 isoforms were found as being conserved in dicotyledons but substituted by non-equivalent residues in monocotyledons. One example of those substitutions concerns a conserved phenylalanine and a conserved tyrosine in monocotyledons and dicotyledons, respectively. Protein structure modelling suggests that the presence of tyrosine would widen the substrate-binding pocket in the dicotyledons, and thereby influence substrate specificity. We discussed the importance of these findings as new hints to investigate why ferulic acid contents and cell wall digestibility differ between the dicotyledon and monocotyledon species.

Polymeric membranes modulate human keratinocyte differentiation in specific epidermal layers.

PubMed

Salerno, Simona; Morelli, Sabrina; Giordano, Francesca; Gordano, Amalia; Bartolo, Loredana De

2016-10-01

In vitro models of human bioengineered skin substitutes are an alternative to animal experimentation for testing the effects and toxicity of drugs, cosmetics and pollutants. For the first time specific and distinct human epidermal strata were engineered by using membranes and keratinocytes. To this purpose, biodegradable membranes of chitosan (CHT), polycaprolactone (PCL) and a polymeric blend of CHT-PCL were prepared by phase-inversion technique and characterized in order to evaluate their morphological, physico-chemical and mechanical properties. The capability of membranes to modulate keratinocyte differentiation inducing specific interactions in epidermal membrane systems was investigated. The overall results demonstrated that the membrane properties strongly influence the cell morpho-functional behaviour of human keratinocytes, modulating their terminal differentiation, with the creation of specific epidermal strata or a fully proliferative epidermal multilayer system. In particular, human keratinocytes adhered on CHT and CHT-PCL membranes, forming the structure of the epidermal top layers, such as the corneum and granulosum strata, characterized by withdrawal or reduction from the cell cycle and cell proliferation. On the PCL membrane, keratinocytes developed an epidermal basal lamina, with high proliferating cells that stratified and migrated over time to form a complete differentiating epidermal multilayer system. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of an oil spill on the leaf anatomical characteristics of a beach plant (Terminalia catappa L.).

PubMed

Punwong, Paramita; Juprasong, Yotin; Traiperm, Paweena

2017-09-01

This study investigated the short-term impacts of an oil spill on the leaf anatomical structures of Terminalia catappa L. from crude oil leakage in Rayong province, Thailand, in 2013. Approximately 3 weeks after the oil spill, leaves of T. catappa were collected along the coastline of Rayong from one affected site, five adjacent sites, and a control site. Slides of the leaf epidermis were prepared by the peeling method, while leaf and petiole transverse sections were prepared by paraffin embedding. Cell walls of adaxial epidermal cell on leaves in the affected site were straight instead of the jigsaw shape found in leaves from the adjacent and control sites. In addition, the stomatal index of the abaxial leaf surface was significantly lower in the affected site. Leaf and petiole transverse sections collected from the affected site showed increased cuticle thickness, epidermal cell diameter on both sides, and palisade mesophyll thickness; in contrast, vessel diameter and spongy mesophyll thickness were reduced. These significant changes in the leaf anatomy of T. catappa correspond with previous research and demonstrate the negative effects of oil spill pollution on plants. The anatomical changes of T. catappa in response to crude oil pollution are discussed as a possible indicator of pollution and may be used in monitoring crude oil pollution.

Planar cell polarity pathway in vertebrate epidermal development, homeostasis and repair

PubMed Central

Dworkin, Sebastian; Jane, Stephen M

2011-01-01

The planar cell polarity (PCP) pathway plays a critical role in diverse developmental processes that require coordinated cellular movement, including neural tube closure and renal tubulogenesis. Recent studies have demonstrated that this pathway also has emerging relevance to the epidermis, as PCP signaling underpins many aspects of skin biology and pathology, including epidermal development, hair orientation, stem cell division and cancer. Coordinated cellular movement required for epidermal repair in mammals is also regulated by PCP signaling, and in this context, a new PCP gene encoding the developmental transcription factor Grainyhead-like 3 (Grhl3) is critical. This review focuses on the role that PCP signaling plays in the skin across a variety of epidermal functions and highlights perturbations that induce epidermal pathologies. PMID:22041517

Genetic analysis of Ras genes in epidermal development and tumorigenesis

PubMed Central

Drosten, Matthias; Lechuga, Carmen G; Barbacid, Mariano

2013-01-01

Proliferation and differentiation of epidermal keratinocytes are tightly controlled to ensure proper development and homeostasis of the epidermis. The Ras family of small GTPases has emerged as a central node in the coordination of cell proliferation in the epidermis. Recent genetic evidence from mouse models has revealed that the intensity of Ras signaling modulates the proliferative capacity of epidermal keratinocytes. Interfering with Ras signaling either by combined elimination of the 3 Ras genes from the basal layer of the epidermis or by overexpression of dominant-negative Ras isoforms caused epidermal thinning due to hypoproliferation of keratinocytes. In contrast, overexpression of oncogenic Ras mutants in different epidermal cell layers led to hyperproliferative phenotypes including the development of papillomas and squamous cell carcinomas. Here, we discuss the value of loss- and gain-of-function studies in mouse models to assess the role of Ras signaling in the control of epidermal proliferation. PMID:24150175

Gain-of-function mutation of AtDICE1, encoding a putative endoplasmic reticulum-localized membrane protein, causes defects in anisotropic cell elongation by disturbing cell wall integrity in Arabidopsis.

PubMed

Le, Phi-Yen; Jeon, Hyung-Woo; Kim, Min-Ha; Park, Eung-Jun; Lee, Hyoshin; Hwang, Indeok; Han, Kyung-Hwan; Ko, Jae-Heung

2018-04-05

Anisotropic cell elongation depends on cell wall relaxation and cellulose microfibril arrangement. The aim of this study was to characterize the molecular function of AtDICE1 encoding a novel transmembrane protein involved in anisotropic cell elongation in Arabidopsis. Phenotypic characterizations of transgenic Arabidopsis plants mis-regulating AtDICE1 expression with different pharmacological treatments were made, and biochemical, cell biological and transcriptome analyses were performed. Upregulation of AtDICE1 in Arabidopsis (35S::AtDICE1) resulted in severe dwarfism, probably caused by defects in anisotropic cell elongation. Epidermal cell swelling was evident in all tissues, and abnormal secondary wall thickenings were observed in pith cells of stems. These phenotypes were reproduced not only by inducible expression of AtDICE1 but also by overexpression of its poplar homologue in Arabidopsis. RNA interference suppression lines of AtDICE1 resulted in no observable phenotypic changes. Interestingly, wild-type plants treated with isoxaben, a cellulose biosynthesis inhibitor, phenocopied the 35S::AtDICE1 plants, suggesting that cellulose biosynthesis was compromised in the 35S::AtDICE1 plants. Indeed, disturbed cortical microtubule arrangements in 35S::AtDICE1/GFP-TuA6 plants were observed, and the cellulose content was significantly reduced in 35S::AtDICE1 plants. A promoter::GUS analysis showed that AtDICE1 is mainly expressed in vascular tissue, and transient expression of GFP:AtDICE1 in tobacco suggests that AtDICE1 is probably localized in the endoplasmic reticulum (ER). In addition, the external N-terminal conserved domain of AtDICE1 was found to be necessary for AtDICE1 function. Whole transcriptome analyses of 35S::AtDICE1 revealed that many genes involved in cell wall modification and stress/defence responses were mis-regulated. AtDICE1, a novel ER-localized transmembrane protein, may contribute to anisotropic cell elongation in the formation of vascular tissue by affecting cellulose biosynthesis.

Epidermal Cell Death in Rice Is Regulated by Ethylene, Gibberellin, and Abscisic Acid

PubMed Central

Steffens, Bianka; Sauter, Margret

2005-01-01

Programmed cell death (PCD) of epidermal cells that cover adventitious root primordia in deepwater rice (Oryza sativa) is induced by submergence. Early suicide of epidermal cells may prevent injury to the growing root that emerges under flooding conditions. Induction of PCD is dependent on ethylene signaling and is further promoted by gibberellin (GA). Ethylene and GA act in a synergistic manner, indicating converging signaling pathways. Treatment of plants with GA alone did not promote PCD. Treatment with the GA biosynthesis inhibitor paclobutrazol resulted in increased PCD in response to ethylene and GA presumably due to an increased sensitivity of epidermal cells to GA. Abscisic acid (ABA) was shown to efficiently delay ethylene-induced as well as GA-promoted cell death. The results point to ethylene signaling as a target of ABA inhibition of PCD. Accumulation of ethylene and GA and a decreased ABA level in the rice internode thus favor induction of epidermal cell death and ensure that PCD is initiated as an early response that precedes adventitious root growth. PMID:16169967

Inactivated Wnt signaling in resveratrol-treated epidermal squamous cancer cells and its biological implication

PubMed Central

Liu, Zhi-Li; Li, Hong; Liu, Jia; Wu, Mo-Li; Chen, Xiao-Yan; Liu, Li-Hong; Wang, Qian

2017-01-01

Squamous cell carcinoma (SCC) is the most common epidermal malignancy, and Wnt/β-catenin signaling is frequently activated in SCC. Resveratrol prevents rodent epidermal carcinogenesis, while its effect on human epidermal cancer remains unknown. To address this issue, the impact of resveratrol on the growth and Wnt signaling of skin SCC Colo16 cells were investigated at the cellular and molecular biology levels by flow cytometry, immunocytochemistry, reverse transcription-polymerase chain reaction, western blotting and β-catenin-specific small interfering RNA (siRNA) transfection. Resveratrol (100 µM) suppressed cell growth and induced apoptosis in Colo16 cells. Wnt2 and its downstream genes were downregulated, which was accompanied by increased expression of the Wnt signaling inhibitor Axin2. Transfection with a β-catenin-specific siRNA did not affect cell growth but enhanced the resveratrol susceptibility of Colo16 transfectants. The present results suggest the inhibitory effects of resveratrol on epidermal SCCs and inactivation of Wnt signaling as one of the resveratrol-caused molecular events in Colo16 cells. β-catenin oriented siRNA is insufficient to induce cell crisis, implicating the presence of more critical cancer-associated element(s) as the target in Colo16 cells. PMID:28781663

Modeling the Morphogenesis of Epidermal Tissues on the Surface of a 3D Last

NASA Astrophysics Data System (ADS)

McCleery, W. Tyler; Crews, Sarah M.; Mashburn, David N.; Veldhuis, Jim; Brodland, G. Wayne; Hutson, M. Shane

2014-03-01

Embryogenesis in the fruit fly Drosophila melanogaster is coordinated by the interaction of cells in adjacent tissues. For some events of embryogenesis, e.g., dorsal closure, two-dimensional models have been sufficient to elucidate the relevant cell and tissue mechanics. Here, we describe a new three-dimensional cell-level finite element model for investigating germ band retraction - a morphogenetic event where one epidermal tissue, the germ band, initially wraps around the posterior end of the ellipsoidal embryo. This tissue then retracts with a mechanical assist from contraction of cells in a second epidermal tissue, the amnioserosa. To speed simulation run times and focus on the relevant tissues, we only model epidermal tissue interactions. Epidermal cells are defined as polygons constrained to lie on the surface of the ellipsoidal last, but have adjustable parameters such as edge tensions and cell pressures. Tissue movements are simulated by balancing these dynamic cell-level forces with viscous resistance and allowing cells to exchange neighbors. Our choice of modeling parameters is informed by in vivo measurements of cell-level forces using laser microsurgery. We use this model to investigate the multicellular stress fields in normal and aberrant development.

Functions of Vγ4 T Cells and Dendritic Epidermal T Cells on Skin Wound Healing

PubMed Central

Li, Yashu; Wu, Jun; Luo, Gaoxing; He, Weifeng

2018-01-01

Wound healing is a complex and dynamic process that progresses through the distinct phases of hemostasis, inflammation, proliferation, and remodeling. Both inflammation and re-epithelialization, in which skin γδ T cells are heavily involved, are required for efficient skin wound healing. Dendritic epidermal T cells (DETCs), which reside in murine epidermis, are activated to secrete epidermal cell growth factors, such as IGF-1 and KGF-1/2, to promote re-epithelialization after skin injury. Epidermal IL-15 is not only required for DETC homeostasis in the intact epidermis but it also facilitates the activation and IGF-1 production of DETC after skin injury. Further, the epidermal expression of IL-15 and IGF-1 constitutes a feedback regulatory loop to promote wound repair. Dermis-resident Vγ4 T cells infiltrate into the epidermis at the wound edges through the CCR6-CCL20 pathway after skin injury and provide a major source of IL-17A, which enhances the production of IL-1β and IL-23 in the epidermis to form a positive feedback loop for the initiation and amplification of local inflammation at the early stages of wound healing. IL-1β and IL-23 suppress the production of IGF-1 by DETCs and, therefore, impede wound healing. A functional loop may exist among Vγ4 T cells, epidermal cells, and DETCs to regulate wound repair.

SABRE is required for stabilization of root hair patterning in Arabidopsis thaliana.

PubMed

Pietra, Stefano; Lang, Patricia; Grebe, Markus

2015-03-01

Patterned differentiation of distinct cell types is essential for the development of multicellular organisms. The root epidermis of Arabidopsis thaliana is composed of alternating files of root hair and non-hair cells and represents a model system for studying the control of cell-fate acquisition. Epidermal cell fate is regulated by a network of genes that translate positional information from the underlying cortical cell layer into a specific pattern of differentiated cells. While much is known about the genes of this network, new players continue to be discovered. Here we show that the SABRE (SAB) gene, known to mediate microtubule organization, anisotropic cell growth and planar polarity, has an effect on root epidermal hair cell patterning. Loss of SAB function results in ectopic root hair formation and destabilizes the expression of cell fate and differentiation markers in the root epidermis, including expression of the WEREWOLF (WER) and GLABRA2 (GL2) genes. Double mutant analysis reveal that wer and caprice (cpc) mutants, defective in core components of the epidermal patterning pathway, genetically interact with sab. This suggests that SAB may act on epidermal patterning upstream of WER and CPC. Hence, we provide evidence for a role of SAB in root epidermal patterning by affecting cell-fate stabilization. Our work opens the door for future studies addressing SAB-dependent functions of the cytoskeleton during root epidermal patterning. © 2014 The Authors. Physiologia Plantarum published by John Wiley & Sons Ltd on behalf of Scandinavian Plant Physiology Society.

Roles of CONSTITUTIVE PHOTOMORPHOGENIC 10 in Arabidopsis stomata development

PubMed Central

Delgado, Dolores; Ballesteros, Isabel; Mena, Montaña; Fenoll, Carmen

2012-01-01

Stomata are epidermal bi-celled structures that differentiate within special cell lineages initiated by a subset of protodermal cells. Recently, we showed that the Arabidopsis photomorphogenic repressor COP10 controls specific cell-lineage and cell-signaling developmental mechanisms in stomatal lineages. Loss-of-function cop10-1 mutant cotyledons and leaves produced (in the light and in the dark) abundant stomatal clusters, but nonlineage epidermal cells were not affected. Here we examine COP10 role in hypocotyls, cylindrical organs displaying a distinct epidermal organization with alternate files of protruding and non-protruding cells, with the latter producing a limited number of stomata. COP10 prevents stomatal clusters and restricts stomata production in hypocotyls; these roles are specific to lineage cells as in cotyledons, since COP10 loss of function does not elicit stomatal fate in nonlineage cells; COP10 also sustains the directional cell expansion of all hypocotyl epidermal cell types, and seems necessary for the differentiation between protruding and non-protruding cell files. PMID:22836493

Arctigenin induced gallbladder cancer senescence through modulating epidermal growth factor receptor pathway.

PubMed

Zhang, Mingdi; Cai, Shizhong; Zuo, Bin; Gong, Wei; Tang, Zhaohui; Zhou, Di; Weng, Mingzhe; Qin, Yiyu; Wang, Shouhua; Liu, Jun; Ma, Fei; Quan, Zhiwei

2017-05-01

Gallbladder cancer has poor prognosis and limited therapeutic options. Arctigenin, a representative dibenzylbutyrolactone lignan, occurs in a variety of plants. However, the molecular mechanisms involved in the antitumor effect of arctigenin on gallbladder cancer have not been fully elucidated. The expression levels of epidermal growth factor receptor were examined in 100 matched pairs of gallbladder cancer tissues. A positive correlation between high epidermal growth factor receptor expression levels and poor prognosis was observed in gallbladder cancer tissues. Pharmacological inhibition or inhibition via RNA interference of epidermal growth factor receptor induced cellular senescence in gallbladder cancer cells. The antitumor effect of arctigenin on gallbladder cancer cells was primarily achieved by inducing cellular senescence. In gallbladder cancer cells treated with arctigenin, the expression level of epidermal growth factor receptor significantly decreased. The analysis of the activity of the kinases downstream of epidermal growth factor receptor revealed that the RAF-MEK-ERK signaling pathway was significantly inhibited. Furthermore, the cellular senescence induced by arctigenin could be reverted by pcDNA-epidermal growth factor receptor. Arctigenin also potently inhibited the growth of tumor xenografts, which was accompanied by the downregulation of epidermal growth factor receptor and induction of senescence. This study demonstrates arctigenin could induce cellular senescence in gallbladder cancer through the modulation of epidermal growth factor receptor pathway. These data identify epidermal growth factor receptor as a key regulator in arctigenin-induced gallbladder cancer senescence.

Ampullary organs and electroreception in freshwater Carcharhinus leucas.

PubMed

Whitehead, Darryl L

2002-01-01

The ampulla of Lorenzini of juvenile Carcharhlinus leucas differ histologically from those previously described for other elasmobranchs. The wall of the ampullary canal consists of protruding hillock-shaped epidermal cells that appear to secrete large quantities of a mucopolysaccharide gel. The ampullary organs comprise a long canal sheathed in collagen terminating in an ampulla. Each ampulla contains six alveolar sacs, with each sac containing hundreds of receptor cells. The receptor cells are characteristic of others described for elasmobranchs being pear-shaped cells with a central nucleus and bearing a single kinocilium in the exposed apical region of the cell. The supportive cells differ from general elasmobranch ampullary histology in that some have an apical nucleus. These ampullary structures allow Carcharhinus leucas to detect and respond to artificial electrical fields. Carcharhinus leucas from freshwater habitats respond to electrical signals supplied in freshwater aquaria by abruptly turning towards low voltage stimuli (< or = 10 microA) and either swimming over or biting at the origin of the stimulus.

A theoretical approach to the relationship between wettability and surface microstructures of epidermal cells and structured cuticles of flower petals

PubMed Central

Taneda, Haruhiko; Watanabe-Taneda, Ayako; Chhetry, Rita; Ikeda, Hiroshi

2015-01-01

Background and Aims The epidermal surface of a flower petal is composed of convex cells covered with a structured cuticle, and the roughness of the surface is related to the wettability of the petal. If the surface remains wet for an excessive amount of time the attractiveness of the petal to floral visitors may be impaired, and adhesion of pathogens may be promoted. However, it remains unclear how the epidermal cells and structured cuticle contribute to surface wettability of a petal. Methods By considering the additive effects of the epidermal cells and structured cuticle on petal wettability, a thermodynamic model was developed to predict the wetting mode and contact angle of a water droplet at a minimum free energy. Quantitative relationships between petal wettability and the geometries of the epidermal cells and the structured cuticle were then estimated. Measurements of contact angles and anatomical traits of petals were made on seven herbaceous species commonly found in alpine habitats in eastern Nepal, and the measured wettability values were compared with those predicted by the model using the measured geometries of the epidermal cells and structured cuticles. Key Results The model indicated that surface wettability depends on the height and interval between cuticular steps, and on a height-to-width ratio for epidermal cells if a thick hydrophobic cuticle layer covers the surface. For a petal epidermis consisting of lenticular cells, a repellent surface results when the cuticular step height is greater than 0·85 µm and the height-to-width ratio of the epidermal cells is greater than 0·3. For an epidermis consisting of papillate cells, a height-to-width ratio of greater than 1·1 produces a repellent surface. In contrast, if the surface is covered with a thin cuticle layer, the petal is highly wettable (hydrophilic) irrespective of the roughness of the surface. These predictions were supported by the measurements of petal wettability made on flowers of alpine species. Conclusions The results indicate that surface roughness caused by epidermal cells and a structured cuticle produces a wide range of petal wettability, and that this can be successfully modelled using a thermodynamic approach. PMID:25851137

Immortalized N/TERT keratinocytes as an alternative cell source in 3D human epidermal models.

PubMed

Smits, Jos P H; Niehues, Hanna; Rikken, Gijs; van Vlijmen-Willems, Ivonne M J J; van de Zande, Guillaume W H J F; Zeeuwen, Patrick L J M; Schalkwijk, Joost; van den Bogaard, Ellen H

2017-09-19

The strong societal urge to reduce the use of experimental animals, and the biological differences between rodent and human skin, have led to the development of alternative models for healthy and diseased human skin. However, the limited availability of primary keratinocytes to generate such models hampers large-scale implementation of skin models in biomedical, toxicological, and pharmaceutical research. Immortalized cell lines may overcome these issues, however, few immortalized human keratinocyte cell lines are available and most do not form a fully stratified epithelium. In this study we compared two immortalized keratinocyte cell lines (N/TERT1, N/TERT2G) to human primary keratinocytes based on epidermal differentiation, response to inflammatory mediators, and the development of normal and inflammatory human epidermal equivalents (HEEs). Stratum corneum permeability, epidermal morphology, and expression of epidermal differentiation and host defence genes and proteins in N/TERT-HEE cultures was similar to that of primary human keratinocytes. We successfully generated N/TERT-HEEs with psoriasis or atopic dermatitis features and validated these models for drug-screening purposes. We conclude that the N/TERT keratinocyte cell lines are useful substitutes for primary human keratinocytes thereby providing a biologically relevant, unlimited cell source for in vitro studies on epidermal biology, inflammatory skin disease pathogenesis and therapeutics.

Dynamics of keratinocytes in vivo using HO labeling: a sensitive marker of epidermal proliferation state.

PubMed

Hsieh, Elaine A; Chai, Christine M; de Lumen, Benito O; Neese, Richard A; Hellerstein, Marc K

2004-09-01

A heavy water ((2)H(2)O) labeling method recently developed to measure cell proliferation in vivo is applied here to the measurement of murine epidermal cell turnover and to investigate conditions in which keratinocyte proliferation is either inhibited or stimulated. The technique is based on incorporation of (2)H(2)O into the deoxyribose moiety of deoxyribonucleotides in dividing cells. Label incorporation and die-away studies in cells isolated from C57BL/6J mouse epidermis revealed the replacement rate to be 34%-44% per wk (half-life of 1.6-2 wk). The kinetics provided evidence of a non-proliferative subpopulation of cells (10%-15% of the total) within the epidermis. Topical administration of 7,12-dimethylbenz(a)anthracene and 12-O-tetradecanoylphorbol-13-acetate for 3 wk increased epidermal cell proliferation by 55% in SENCAR mice. Topical addition of lunasin, an anti-mitotic agent from soy, decreased epidermal cell proliferation modestly though significantly (16% given alone, 9% given with carcinogens). Caloric restriction (by 33% of energy intake) for 4 wk decreased the epidermal cell proliferation rate by 45% in C57BL/6J mice. In summary, epidermal cell proliferation can be measured in vivo using (2)H(2)O labeling in normal, hyper- and hypo-proliferative conditions. Potential applications of this inherently safe method in humans might include studies of psoriasis, wound healing, chemopreventive agents, and caloric intake.

Oral mucosa: an alternative epidermic cell source to develop autologous dermal-epidermal substitutes from diabetic subjects.

PubMed

Guzmán-Uribe, Daniela; Alvarado-Estrada, Keila Neri; Pierdant-Pérez, Mauricio; Torres-Álvarez, Bertha; Sánchez-Aguilar, Jesus Martin; Rosales-Ibáñez, Raúl

2017-01-01

The aim of this study was to obtain autologous dermal-epidermal skin substitutes from oral mucosa from diabetic subjects as a first step towards a possible clinical application for cases of diabetic foot. Oral mucosa was obtained from diabetic and healthy subjects (n=20 per group). Epidermal cells were isolated and cultured using autologous fibrin to develop dermal-epidermal in vitro substitutes by the air-liquid technique with autologous human serum as a supplement media. Substitutes were immunocharacterized with collagen IV and cytokeratin 5-14 as specific markers. A Student´s t- test was performed to assess the differences between both groups. It was possible to isolate epidermal cells from the oral mucosa of diabetic and healthy subjects and develop autologous dermal-epidermal skin substitutes using autologous serum as a supplement. Differences in the expression of specific markers were observed and the cytokeratin 5-14 expression was lower in the diabetic substitutes, and the collagen IV expression was higher in the diabetic substitutes when compared with the healthy group, showing a significant difference. Cells from oral mucosa could be an alternative and less invasive source for skin substitutes and wound healing. A difference in collagen production of diabetic cells suggests diabetic substitutes could improve diabetic wound healing. More research is needed to determine the crosstalk between components of these skin substitutes and damaged tissues.

Embryonic control of epidermal cell patterning in the root and hypocotyl of Arabidopsis.

PubMed

Lin, Y; Schiefelbein, J

2001-10-01

A position-dependent pattern of epidermal cell types is produced during the development of the Arabidopsis seedling root and hypocotyl. To understand the origin and regulation of this patterning mechanism, we have examined the embryonic expression of the GLABRA2 (GL2) gene, which encodes a cell-type-specific transcription factor. Using in situ RNA hybridization and a sensitive GL2::GFP reporter, we discovered that a position-dependent pattern of GL2 expression is established within protodermal cells at the heart stage and is maintained throughout the remainder of embryogenesis. In addition, we show that an exceptional GL2 expression character and epidermal cell pattern arises during development of the root-hypocotyl junction, which represents an anatomical transition zone. Furthermore, we find that two of the genes regulating seedling epidermal patterning, TRANSPARENT TESTA GLABRA (TTG) and WEREWOLF (WER), also control the embryonic GL2 pattern, whereas the CAPRICE (CPC) and GL2 genes are not required to establish this pattern. These results indicate that position-dependent patterning of epidermal cell types begins at an early stage of embryogenesis, before formation of the apical meristems and shortly after the cellular anatomy of the protoderm and outer ground tissue layer is established. Thus, epidermal cell specification in the Arabidopsis seedling relies on the embryonic establishment of a patterning mechanism that is perpetuated postembryonically.

Steroids are required for epidermal cell fate establishment in Arabidopsis roots.

PubMed

Kuppusamy, Kavitha T; Chen, Andrew Y; Nemhauser, Jennifer L

2009-05-12

The simple structure of Arabidopsis roots provides an excellent model system to study epidermal cell fate specification. Epidermal cells in contact with 2 underlying cortical cells differentiate into hair cells (H cells; trichoblasts), whereas cells that contact only a single cortical cell differentiate into mature hairless cells (N cells; atrichoblasts). This position-dependent patterning, in combination with the constrained orientation of cell divisions, results in hair and nonhair cell files running longitudinally along the root epidermis. Here, we present strong evidence that steroid hormones called brassinosteroids (BRs) are required to maintain position-dependent fate specification in roots. We show that BRs are required for normal expression levels and patterns of WEREWOLF (WER) and GLABRA2 (GL2), master regulators of epidermal patterning. Loss of BR signaling results in loss of hair cells in H positions, likely as a consequence of reduced expression of CAPRICE (CPC), a direct downstream target of WER. Our observations demonstrate that in addition to their well-known role in cell expansion, BRs play an essential role in directing cell fate.

Steroids are required for epidermal cell fate establishment in Arabidopsis roots

PubMed Central

Kuppusamy, Kavitha T.; Chen, Andrew Y.; Nemhauser, Jennifer L.

2009-01-01

The simple structure of Arabidopsis roots provides an excellent model system to study epidermal cell fate specification. Epidermal cells in contact with 2 underlying cortical cells differentiate into hair cells (H cells; trichoblasts), whereas cells that contact only a single cortical cell differentiate into mature hairless cells (N cells; atrichoblasts). This position-dependent patterning, in combination with the constrained orientation of cell divisions, results in hair and nonhair cell files running longitudinally along the root epidermis. Here, we present strong evidence that steroid hormones called brassinosteroids (BRs) are required to maintain position-dependent fate specification in roots. We show that BRs are required for normal expression levels and patterns of WEREWOLF (WER) and GLABRA2 (GL2), master regulators of epidermal patterning. Loss of BR signaling results in loss of hair cells in H positions, likely as a consequence of reduced expression of CAPRICE (CPC), a direct downstream target of WER. Our observations demonstrate that in addition to their well-known role in cell expansion, BRs play an essential role in directing cell fate. PMID:19416891

Oral mucosa: an alternative epidermic cell source to develop autologous dermal-epidermal substitutes from diabetic subjects

PubMed Central

GUZMÁN-URIBE, Daniela; ALVARADO-ESTRADA, Keila Neri; PIERDANT-PÉREZ, Mauricio; TORRES-ÁLVAREZ, Bertha; SÁNCHEZ-AGUILAR, Jesus Martin; ROSALES-IBÁÑEZ, Raúl

2017-01-01

Abstract Oral mucosa has been highlighted as a suitable source of epidermal cells due to its intrinsic characteristics such as its higher proliferation rate and its obtainability. Diabetic ulcers have a worldwide prevalence that is variable (1%-11%), meanwhile treatment of this has been proven ineffective. Tissue-engineered skin plays an important role in wound care focusing on strategies such autologous dermal-epidermal substitutes. Objective The aim of this study was to obtain autologous dermal-epidermal skin substitutes from oral mucosa from diabetic subjects as a first step towards a possible clinical application for cases of diabetic foot. Material and Methods Oral mucosa was obtained from diabetic and healthy subjects (n=20 per group). Epidermal cells were isolated and cultured using autologous fibrin to develop dermal-epidermal in vitro substitutes by the air-liquid technique with autologous human serum as a supplement media. Substitutes were immunocharacterized with collagen IV and cytokeratin 5-14 as specific markers. A Student´s t- test was performed to assess the differences between both groups. Results It was possible to isolate epidermal cells from the oral mucosa of diabetic and healthy subjects and develop autologous dermal-epidermal skin substitutes using autologous serum as a supplement. Differences in the expression of specific markers were observed and the cytokeratin 5-14 expression was lower in the diabetic substitutes, and the collagen IV expression was higher in the diabetic substitutes when compared with the healthy group, showing a significant difference. Conclusion Cells from oral mucosa could be an alternative and less invasive source for skin substitutes and wound healing. A difference in collagen production of diabetic cells suggests diabetic substitutes could improve diabetic wound healing. More research is needed to determine the crosstalk between components of these skin substitutes and damaged tissues. PMID:28403359

Elaiophores in Gomesa bifolia (Sims) M.W. Chase & N.H. Williams (Oncidiinae: Cymbidieae: Orchidaceae): structure and oil secretion

PubMed Central

Aliscioni, Sandra S.; Torretta, Juan P.; Bello, Mariano E.; Galati, Beatriz G.

2009-01-01

Background and Aims Oils are an unusual floral reward in Orchidaceae, being produced by specialized glands called elaiophores. Such glands have been described in subtribe Oncidiinae for a few species. The aims of the present study were to identify the presence of elaiophores in Gomesa bifolia, to study their structure and to understand how the oil is secreted. Additionally, elaiophores of G. bifolia were compared with those of related taxa within the Oncidiinae. Methods Elaiophores were identified using Sudan III. Their structure was examined by using light, scanning electron and transmission electron microscopy. Key Results Secretion of oils was from the tips of callus protrusions. The secretory cells each had a large, centrally located nucleus, highly dense cytoplasm, abundant plastids containing lipid globules associated with starch grains, numerous mitochondria, an extensive system of rough and smooth endoplasmatic reticulum, and electron-dense dictyosomes. The outer tangential walls were thick, with a loose cellulose matrix and a few, sparsely distributed inconspicuous cavities. Electron-dense structures were observed in the cell wall and formed a lipid layer that covered the cuticle of the epidermal cells. The cuticle as viewed under the scanning electron microscope was irregularly rugose. Conclusions The elaiophores of G. bifolia are of the epithelial type. The general structure of the secretory cells resembles that described for other species of Oncidiinae, but some unique features were encountered for this species. The oil appears to pass through the outer tangential wall and the cuticle, covering the latter without forming cuticular blisters. PMID:19692391

Epidermal Notch signalling: differentiation, cancer and adhesion.

PubMed

Watt, Fiona M; Estrach, Soline; Ambler, Carrie A

2008-04-01

The Notch pathway plays an important role in regulating epidermal differentiation. Notch ligands, receptors and effectors are expressed in a complex and dynamic pattern in embryonic and adult skin. Genetic ablation or activation of the pathway reveals that Notch signalling promotes differentiation of the hair follicle, sebaceous gland and interfollicular epidermal lineages and that Notch acts as an epidermal tumour suppressor. Notch signalling interacts with a range of other pathways to fulfil these functions and acts via RBP-Jkappa dependent and independent mechanisms. The effects on differentiation can be cell autonomous and non-autonomous, and Notch contributes to stem cell clustering via modulation of cell adhesion.

Copper microlocalisation and changes in leaf morphology, chloroplast ultrastructure and antioxidative response in white lupin and soybean grown in copper excess.

PubMed

Sánchez-Pardo, Beatriz; Fernández-Pascual, Mercedes; Zornoza, Pilar

2014-01-01

The microlocalisation of Cu was examined in the leaves of white lupin and soybean grown hydroponically in the presence of 1.6 (control) or 192 μM (excess) Cu, along with its effect on leaf morphology, (ultra)structure and the antioxidative response. The 192 μM dose led to a reduction in the total leaf area and leaf thickness in both species, although more strongly so in white lupin. In the latter species it was also associated with smaller spongy parenchyma cells, and smaller spaces between them, while in the soybean it more strongly reduced the size of the palisade parenchyma and epidermal cells. Energy-dispersive X-ray microanalysis showed that under Cu excess the metal was mainly localised inside the spongy parenchyma cells of the white lupin leaves, and in the lower epidermis cell walls in those of the soybean. Cu excess also promoted ultrastructural chloroplast alterations, reducing the photosynthetic capacity index and the green area of the leaves, especially in the soybean. Despite this, soybean appeared to be more tolerant to Cu excess than white lupin, because soybean displayed (1) lower accumulation of Cu in the leaves, (2) enhanced microlocalisation of Cu in the cell walls and (3) greater levels of induced total -SH content and superoxide dismutase and catalase activities that are expected for better antioxidative responses.

Human eccrine sweat gland cells turn into melanin-uptaking keratinocytes in dermo-epidermal skin substitutes.

PubMed

Böttcher-Haberzeth, Sophie; Biedermann, Thomas; Pontiggia, Luca; Braziulis, Erik; Schiestl, Clemens; Hendriks, Bart; Eichhoff, Ossia M; Widmer, Daniel S; Meuli-Simmen, Claudia; Meuli, Martin; Reichmann, Ernst

2013-02-01

Recently, Biedermann et al. (2010) have demonstrated that human eccrine sweat gland cells can develop a multilayered epidermis. The question still remains whether these cells can fulfill exclusive and very specific functional properties of epidermal keratinocytes, such as the incorporation of melanin, a feature absent in sweat gland cells. We added human melanocytes to eccrine sweat gland cells to let them develop into an epidermal analog in vivo. The interaction between melanocytes and sweat gland-derived keratinocytes was investigated. The following results were gained: (1) macroscopically, a pigmentation of the substitutes was seen 2-3 weeks after transplantation; (2) we confirmed the development of a multilayered, stratified epidermis with melanocytes distributed evenly throughout the basal layer; (3) melanocytic dendrites projected to suprabasal layers; and (4) melanin was observed to be integrated into former eccrine sweat gland cells. These skin substitutes were similar or equal to skin substitutes cultured from human epidermal keratinocytes. The only differences observed were a delay in pigmentation and less melanin uptake. These data suggest that eccrine sweat gland cells can form a functional epidermal melanin unit, thereby providing striking evidence that they can assume one of the most characteristic keratinocyte properties.

Histone deacetylases inhibitor Trichostatin A ameliorates DNFB-induced allergic contact dermatitis and reduces epidermal Langerhans cells in mice

PubMed Central

Shi, Yu-Ling; Gu, Jun; Park, Jun-Yang; Xu, Ying-Ping; Yu, Fu-Shin; Zhou, Li; Mi, Qing-Sheng

2012-01-01

Background Histone deacetylases (HDACs) influence chromatin organization, representing a key epigenetic regulatory mechanism in cells. Trichostatin A (TSA), a potent HDAC inhibitor, has anti-tumor and anti-inflammatory effects. Allergic contact dermatitis (ACD) is a T-cell-mediated inflammatory reaction in skin and is regulated by epidermal Langerhans cells (LCs). Objective The aim of this study was to investigate if TSA treatment prevents 2,4-dinitrofluorobenzene (DNFB)-induced ACD in mice and regulates epidermal LCs and other immune cells during ACD development. Methods ACD was induced by sensitizing and challenging with DNFB topically. Mice were treated intraperitoneally with TSA or vehicle DMSO as a control every other day before and during induction of ACD. The ear swelling response was measured and skin biopsies from sensitized skin areas were obtained for histology. Epidermal cells, thymus, spleens and skin draining lymph nodes were collected for immune staining. Results TSA treatment ameliorated skin lesion severity of DNFB-induced ACD. The percentages of epidermal LCs and splenic DCs as well as LC maturation were significantly reduced in TSA-treated mice. However, TSA treatment did not significantly affect the homeostasis of conventional CD4+ and CD8+ T cells, Foxp3+CD4+ regulatory T cells, iNKT cells, and γδ T cells in thymus, spleen and draining lymph nodes (dLNs). Furthermore, there were no significant differences in IL-4 and IFN-γ-producing T cells and iNKT cells between TSA- and DMSO-treated mice. Conclusion Our findings suggest that TSA may ameliorate ACD through the regulation of epidermal LCs and HDACs could serve as potential therapeutic targets for ACD and other LCs-related skin diseases. PMID:22999682

An unusual melanocytic lesion associated with eccrine duct fibroadenomatosis and syringoid features.

PubMed

Stefanato, C M; Simkin, D A; Bhawan, J

2001-04-01

The intimate association of nevomelanocytic nevi with eccrine ducts commonly seen in congenital nevi was emphasized by Mishima, who described as eccrine-centered nevi those lesions characterized by nevomelanocytic cells predominantly proliferating around and within the eccrine sweat duct walls. However, there were no changes in the overlying epidermis, dermis, or eccrine acrosyringeal or dermal duct proliferation in these lesions. We present the case of a 16-year-old boy with a 1-year-history of a 0.6-cm diameter single tan papule on the right heel, clinically thought to be a Spitz nevus. Histopathologic examination revealed a compound nevomelanocytic nevus associated with epidermal hyperplasia, thin anastomosing cords of acrosyringeal epithelium extending within the dermis, and eccrine ductal proliferation in a syringoma-like pattern associated with a dense fibrous stroma. Features that distinguish our case from eccrine-centered nevus are that the latter lacks epidermal and eccrine duct hyperplasia and a dense fibrous stroma. The location of the lesion on the heel in our case suggests the possibility that the pathologic changes observed could result from repetitive trauma.

Direct observation of organic contaminant uptake, storage, and metabolism within plant roots.

PubMed

Wild, Edward; Dent, John; Thomas, Gareth O; Jones, Kevin C

2005-05-15

Two-photon excitation microscopy (TPEM) is used to visualize and track the uptake and movement of anthracene and phenanthrene from a contaminated growth medium into living unmodified roots of maize and wheat over a 56-day period. The degradation of anthracene was also directly observed within the cortex cells of both species. The power of this technique is that neither the plant nor the compound require altering (staining or sectioning) to visualize them, meaning they are in their natural form throughout the experiment. Initially both compounds bound to the epidermis along the zone of elongation, passing through the epidermal cells to reach the cortex within the root hair, and branching zones of the root. The PAHs entered the epidermis radially; however, once within the cortex cells this movement was dominated by slow lateral movement of both compounds toward the shoot. Highly focused "streams" of compound were observed to form over time; zones where phenanthrene concentrated extended up to 1500 microm in length over a 56-day period, for example, passing through several adjoining cells, and were detectable in cell walls and cell vacuoles. Radial movement was not observed to extend beyond the cortex cells to reach the vascular tissues of the plant. The longitudinal movement of both compounds was not observed to extend beyond the root base into the stem or vegetative parts of the plant. The lateral movement of both compounds within the cortex cells was dominated by movement within the cell walls, suggesting apoplastic flow through multiple cell walls, but with a low level of symplastic movement to transport compound into the cellular vacuoles. Degradation of anthracene to the partial breakdown products anthrone, anthraquinone, and hydroxyanthraquinone was observed directly in the zones of root elongation and branching. The technique and observations have important applications to the fields of agrochemistry and phytoremediation.

Production and emission of volatile compounds by petal cells.

PubMed

Baudino, Sylvie; Caissard, Jean-Claude; Bergougnoux, Véronique; Jullien, Frédéric; Magnard, Jean-Louis; Scalliet, Gabriel; Cock, J Mark; Hugueney, Philippe

2007-11-01

We localized the tissues and cells that contribute to scent biosynthesis in scented and non-scented Rosa x hybrida cultivars as part of a detailed cytological analysis of the rose petal. Adaxial petal epidermal cells have a typical conical, papillate shape whereas abaxial petal epidermal cells are flat. Using two different techniques, solid/liquid phase extraction and headspace collection of volatiles, we showed that, in roses, both epidermal layers are capable of producing and emitting scent volatiles, despite the different morphologies of the cells of these two tissues. Moreover, OOMT, an enzyme involved in scent molecule biosynthesis, was localized in both epidermal layers. These results are discussed in view of results found in others species such as Antirrhinum majus, where it has been shown that the adaxial epidermis is the preferential site of scent production and emission.

Production and Emission of Volatile Compounds by Petal Cells

PubMed Central

Caissard, Jean-Claude; Bergougnoux, Véronique; Jullien, Frédéric; Magnard, Jean-Louis; Scalliet, Gabriel; Cock, J Mark; Hugueney, Philippe

2007-01-01

We localized the tissues and cells that contribute to scent biosynthesis in scented and non-scented Rosa × hybrida cultivars as part of a detailed cytological analysis of the rose petal. Adaxial petal epidermal cells have a typical conical, papillate shape whereas abaxial petal epidermal cells are flat. Using two different techniques, solid/liquid phase extraction and headspace collection of volatiles, we showed that, in roses, both epidermal layers are capable of producing and emitting scent volatiles, despite the different morphologies of the cells of these two tissues. Moreover, OOMT, an enzyme involved in scent molecule biosynthesis, was localized in both epidermal layers. These results are discussed in view of results found in others species such as Antirrhinum majus, where it has been shown that the adaxial epidermis is the preferential site of scent production and emission. PMID:19704548

The temporal and spatial expression of Claudins in epidermal development and the accelerated program of epidermal differentiation in K14-CaSR transgenic mice.

PubMed

Troy, Tammy-Claire; Li, Yuhua; O'Malley, Lauren; Turksen, Kursad

2007-02-01

The importance of the epidermal permeability barrier (EPB) in protecting the mammalian species against harmful UV irradiation, microorganism invasion and water loss is well recognized, as is the role of calcium (Ca(2+)) in keratinocyte differentiation, cell-cell contact and the EPB. In a previous study, we reported that the overexpression of the Ca(2+)-sensing receptor (CaSR) in the undifferentiated basal cells of the epidermis induced a modified epidermal differentiation program including an accelerated EPB formation in transgenic mice, suggesting a role for CaSR signaling in the differentiation of embryonic epidermal cells during development. We now describe the expression profile of claudins (Cldns) and keratin markers in the accelerated EPB formation of K14-CaSR transgenic mice during development as compared to the wild type from E12.5 to newborn stages. Our data show that the transgenic epidermis undergoes an advanced epidermal differentiation program as compared to the wild type as evidenced morphologically as well as by the expression of K14, K1, loricrin, Cldn6, Cldn18 and Cldn11. In addition, we report for the first time the sequential expression of Cldns in epidermal development and describe that the localization of some Cldns change within the epidermis as it matures. Furthermore, we demonstrate that Cldn6 is expressed very early in epidermal morphogenesis, followed by Cldn18, Cldn11 and Cldn1.

Arabidopsis JAGGED links floral organ patterning to tissue growth by repressing Kip-related cell cycle inhibitors.

PubMed

Schiessl, Katharina; Muiño, Jose M; Sablowski, Robert

2014-02-18

Plant morphogenesis requires coordinated cytoplasmic growth, oriented cell wall extension, and cell cycle progression, but it is debated which of these processes are primary drivers for tissue growth and directly targeted by developmental genes. Here, we used ChIP high-throughput sequencing combined with transcriptome analysis to identify global target genes of the Arabidopsis transcription factor JAGGED (JAG), which promotes growth of the distal region of floral organs. Consistent with the roles of JAG during organ initiation and subsequent distal organ growth, we found that JAG directly repressed genes involved in meristem development, such as CLAVATA1 and HANABA TARANU, and genes involved in the development of the basal region of shoot organs, such as BLADE ON PETIOLE 2 and the GROWTH REGULATORY FACTOR pathway. At the same time, JAG regulated genes involved in tissue polarity, cell wall modification, and cell cycle progression. In particular, JAG directly repressed KIP RELATED PROTEIN 4 (KRP4) and KRP2, which control the transition to the DNA synthesis phase (S-phase) of the cell cycle. The krp2 and krp4 mutations suppressed jag defects in organ growth and in the morphology of petal epidermal cells, showing that the interaction between JAG and KRP genes is functionally relevant. Our work reveals that JAG is a direct mediator between genetic pathways involved in organ patterning and cellular functions required for tissue growth, and it shows that a regulatory gene shapes plant organs by releasing a constraint on S-phase entry.

Vγ4 T Cells Inhibit the Pro-healing Functions of Dendritic Epidermal T Cells to Delay Skin Wound Closure Through IL-17A

PubMed Central

Li, Yashu; Wang, Yangping; Zhou, Lina; Liu, Meixi; Liang, Guangping; Yan, Rongshuai; Jiang, Yufeng; Hao, Jianlei; Zhang, Xiaorong; Hu, Xiaohong; Huang, Yong; Wang, Rupeng; Yin, Zhinan; Wu, Jun; Luo, Gaoxing; He, Weifeng

2018-01-01

Dendritic epidermal T cells (DETCs) and dermal Vγ4 T cells engage in wound re-epithelialization and skin inflammation. However, it remains unknown whether a functional link between Vγ4 T cell pro-inflammation and DETC pro-healing exists to affect the outcome of skin wound closure. Here, we revealed that Vγ4 T cell-derived IL-17A inhibited IGF-1 production by DETCs to delay skin wound healing. Epidermal IL-1β and IL-23 were required for Vγ4 T cells to suppress IGF-1 production by DETCs after skin injury. Moreover, we clarified that IL-1β rather than IL-23 played a more important role in inhibiting IGF-1 production by DETCs in an NF-κB-dependent manner. Together, these findings suggested a mechanistic link between Vγ4 T cell-derived IL-17A, epidermal IL-1β/IL-23, DETC-derived IGF-1, and wound-healing responses in the skin. PMID:29483920

Caenorhabditis elegans anillin (ani-1) regulates neuroblast cytokinesis and epidermal morphogenesis during embryonic development.

PubMed

Fotopoulos, N; Wernike, D; Chen, Y; Makil, N; Marte, A; Piekny, A

2013-11-01

The formation of tissues is essential for metazoan development. During Caenorhabditis elegans embryogenesis, ventral epidermal cells migrate to encase the ventral surface of the embryo in a layer of epidermis by a process known as ventral enclosure. This process is regulated by guidance cues secreted by the underlying neuroblasts. However, since the cues and their receptors are differentially expressed in multiple cell types, the role of the neuroblasts in ventral enclosure is not fully understood. Furthermore, although F-actin is required for epidermal cell migration, it is not known if nonmuscle myosin is also required. Anillin (ANI-1) is an actin and myosin-binding protein that coordinates actin-myosin contractility in the early embryo. Here, we show that ANI-1 localizes to the cleavage furrows of dividing neuroblasts during mid-embryogenesis and is required for their division. Embryos depleted of ani-1 display a range of ventral enclosure phenotypes, where ventral epidermal cells migrate with similar speeds to control embryos, but contralateral neighbors often fail to meet and are misaligned. The ventral enclosure phenotypes in ani-1 RNAi embryos suggest that the position or shape of neuroblasts is important for directing ventral epidermal cell migration, although does not rule out an autonomous requirement for ani-1 in the epidermal cells. Furthermore, we show that rho-1 and other regulators of nonmuscle myosin activity are required for ventral epidermal cell migration. Interestingly, altering nonmuscle myosin contractility alleviates or strengthens ani-1's ventral enclosure phenotypes. Our findings suggest that ventral enclosure is a complex process that likely relies on inputs from multiple tissues. © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

Stimulation of hair follicle stem cell proliferation through an IL-1 dependent activation of γδT-cells

PubMed Central

Dutta, Abhik; Pincha, Neha; Rana, Isha; Ghosh, Subhasri; Witherden, Deborah; Kandyba, Eve; MacLeod, Amanda; Kobielak, Krzysztof; Havran, Wendy L

2017-01-01

The cutaneous wound-healing program is a product of a complex interplay among diverse cell types within the skin. One fundamental process that is mediated by these reciprocal interactions is the mobilization of local stem cell pools to promote tissue regeneration and repair. Using the ablation of epidermal caspase-8 as a model of wound healing in Mus musculus, we analyzed the signaling components responsible for epithelial stem cell proliferation. We found that IL-1α and IL-7 secreted from keratinocytes work in tandem to expand the activated population of resident epidermal γδT-cells. A downstream effect of activated γδT-cells is the preferential proliferation of hair follicle stem cells. By contrast, IL-1α-dependent stimulation of dermal fibroblasts optimally stimulates epidermal stem cell proliferation. These findings provide new mechanistic insights into the regulation and function of epidermal cell–immune cell interactions and into how components that are classically associated with inflammation can differentially influence distinct stem cell niches within a tissue. PMID:29199946

Cellular pattern formation by SCRAMBLED, a leucine-rich repeat receptor-like kinase in Arabidopsis.

PubMed

Kwak, Su-Hwan; Schiefelbein, John

2008-02-01

The appropriate specification of distinct cell types is important for generating the proper tissues and bodies of multicellular organisms. In the root epidermis of Arabidopsis, cell fate determination is accomplished by a transcriptional regulatory circuit that is influenced by positional signaling. A leucine-rich repeat receptor-like kinase, SCRAMBLED (SCM), has been shown to be responsible for the position-dependent aspect of this epidermal pattern. In a recent report, we find that SCM affects the transcriptional regulatory network by down-regulating the WEREWOLF (WER) MYB gene expression in a set of epidermal cells located in a specific position. We also find that SCM and the SCM-related SRF1 and SRF3 are not required for embryonic epidermal patterning and that SRF1 and SRF3 do not act redundantly with SCM. This suggests that distinct positional signaling mechanisms exist for embryonic and post-embryonic epidermal patterning. In this addendum, we discuss the implications of our recent findings and extend our working model for epidermal cell pattering.

Cellular pattern formation by SCRAMBLED, a leucine-rich repeat receptor-like kinase in Arabidopsis

PubMed Central

Kwak, Su-Hwan

2008-01-01

The appropriate specification of distinct cell types is important for generating the proper tissues and bodies of multicellular organisms. In the root epidermis of Arabidopsis, cell fate determination is accomplished by a transcriptional regulatory circuit that is influenced by positional signaling. A leucine-rich repeat receptor-like kinase, SCRAMBLED (SCM), has been shown to be responsible for the position-dependent aspect of this epidermal pattern. In a recent report, we find that SCM affects the transcriptional regulatory network by down-regulating the WEREWOLF (WER) MYB gene expression in a set of epidermal cells located in a specific position. We also find that SCM and the SCM-related SRF1 and SRF3 are not required for embryonic epidermal patterning and that SRF1 and SRF3 do not act redundantly with SCM. This suggests that distinct positional signaling mechanisms exist for embryonic and post-embryonic epidermal patterning. In this addendum, we discuss the implications of our recent findings and extend our working model for epidermal cell pattering. PMID:19704725

The Tomato MIXTA-Like Transcription Factor Coordinates Fruit Epidermis Conical Cell Development and Cuticular Lipid Biosynthesis and Assembly1

PubMed Central

Lotan, Orfa; Alkan, Noam; Tsimbalist, Tatiana; Rechav, Katya; Fernandez-Moreno, Josefina-Patricia; Widemann, Emilie; Grausem, Bernard; Pinot, Franck; Costa, Fabrizio; Aharoni, Asaph

2015-01-01

The epidermis of aerial plant organs is the primary source of building blocks forming the outer surface cuticular layer. To examine the relationship between epidermal cell development and cuticle assembly in the context of fruit surface, we investigated the tomato (Solanum lycopersicum) MIXTA-like gene. MIXTA/MIXTA-like proteins, initially described in snapdragon (Antirrhinum majus) petals, are known regulators of epidermal cell differentiation. Fruit of transgenically silenced SlMIXTA-like tomato plants displayed defects in patterning of conical epidermal cells. They also showed altered postharvest water loss and resistance to pathogens. Transcriptome and cuticular lipids profiling coupled with comprehensive microscopy revealed significant modifications to cuticle assembly and suggested SlMIXTA-like to regulate cutin biosynthesis. Candidate genes likely acting downstream of SlMIXTA-like included cytochrome P450s (CYPs) of the CYP77A and CYP86A subfamilies, LONG-CHAIN ACYL-COA SYNTHETASE2, GLYCEROL-3-PHOSPHATE SN-2-ACYLTRANSFERASE4, and the ATP-BINDING CASSETTE11 cuticular lipids transporter. As part of a larger regulatory network of epidermal cell patterning and L1-layer identity, we found that SlMIXTA-like acts downstream of SlSHINE3 and possibly cooperates with homeodomain Leu zipper IV transcription factors. Hence, SlMIXTA-like is a positive regulator of both cuticle and conical epidermal cell formation in tomato fruit, acting as a mediator of the tight association between fruit cutin polymer formation, cuticle assembly, and epidermal cell patterning. PMID:26443676

Rac1/RhoA antagonism defines cell-to-cell heterogeneity during epidermal morphogenesis in nematodes

PubMed Central

Ouellette, Marie-Hélène

2016-01-01

The antagonism between the GTPases Rac1 and RhoA controls cell-to-cell heterogeneity in isogenic populations of cells in vitro and epithelial morphogenesis in vivo. Its involvement in the regulation of cell-to-cell heterogeneity during epidermal morphogenesis has, however, never been addressed. We used a quantitative cell imaging approach to characterize epidermal morphogenesis at a single-cell level during early elongation of Caenorhabditis elegans embryos. This study reveals that a Rac1-like pathway, involving the Rac/Cdc42 guanine-exchange factor β-PIX/PIX-1 and effector PAK1/PAK-1, and a RhoA-like pathway, involving ROCK/LET-502, control the remodeling of apical junctions and the formation of basolateral protrusions in distinct subsets of hypodermal cells. In these contexts, protrusions adopt lamellipodia or an amoeboid morphology. We propose that lamella formation may reduce tension building at cell–cell junctions during morphogenesis. Cell-autonomous antagonism between these pathways enables cells to switch between Rac1- and RhoA-like morphogenetic programs. This study identifies the first case of cell-to-cell heterogeneity controlled by Rac1/RhoA antagonism during epidermal morphogenesis. PMID:27821782

Duox, Flotillin-2, and Src42A Are Required to Activate or Delimit the Spread of the Transcriptional Response to Epidermal Wounds in Drosophila

PubMed Central

Juarez, Michelle T.; Patterson, Rachel A.; Sandoval-Guillen, Efren; McGinnis, William

2011-01-01

The epidermis is the largest organ of the body for most animals, and the first line of defense against invading pathogens. A breach in the epidermal cell layer triggers a variety of localized responses that in favorable circumstances result in the repair of the wound. Many cellular and genetic responses must be limited to epidermal cells that are close to wounds, but how this is regulated is still poorly understood. The order and hierarchy of epidermal wound signaling factors are also still obscure. The Drosophila embryonic epidermis provides an excellent system to study genes that regulate wound healing processes. We have developed a variety of fluorescent reporters that provide a visible readout of wound-dependent transcriptional activation near epidermal wound sites. A large screen for mutants that alter the activity of these wound reporters has identified seven new genes required to activate or delimit wound-induced transcriptional responses to a narrow zone of cells surrounding wound sites. Among the genes required to delimit the spread of wound responses are Drosophila Flotillin-2 and Src42A, both of which are transcriptionally activated around wound sites. Flotillin-2 and constitutively active Src42A are also sufficient, when overexpressed at high levels, to inhibit wound-induced transcription in epidermal cells. One gene required to activate epidermal wound reporters encodes Dual oxidase, an enzyme that produces hydrogen peroxide. We also find that four biochemical treatments (a serine protease, a Src kinase inhibitor, methyl-ß-cyclodextrin, and hydrogen peroxide) are sufficient to globally activate epidermal wound response genes in Drosophila embryos. We explore the epistatic relationships among the factors that induce or delimit the spread of epidermal wound signals. Our results define new genetic functions that interact to instruct only a limited number of cells around puncture wounds to mount a transcriptional response, mediating local repair and regeneration. PMID:22242003

Cellular, ultrastructural and molecular analyses of epidermal cell development in the planarian Schmidtea mediterranea.

PubMed

Cheng, Li-Chun; Tu, Kimberly C; Seidel, Chris W; Robb, Sofia M C; Guo, Fengli; Sánchez Alvarado, Alejandro

2018-01-15

The epidermis is essential for animal survival, providing both a protective barrier and cellular sensor to external environments. The generally conserved embryonic origin of the epidermis, but the broad morphological and functional diversity of this organ across animals is puzzling. We define the transcriptional regulators underlying epidermal lineage differentiation in the planarian Schmidtea mediterranea, an invertebrate organism that, unlike fruitflies and nematodes, continuously replaces its epidermal cells. We find that Smed-p53, Sox and Pax transcription factors are essential regulators of epidermal homeostasis, and act cooperatively to regulate genes associated with early epidermal precursor cell differentiation, including a tandemly arrayed novel gene family (prog) of secreted proteins. Additionally, we report on the discovery of distinct and previously undescribed secreted organelles whose production is dependent on the transcriptional activity of soxP-3, and which we term Hyman vesicles. Copyright © 2017 Elsevier Inc. All rights reserved.

Hair Follicle Bulge Stem Cells Appear Dispensable for the Acute Phase of Wound Re‐epithelialization

PubMed Central

Garcin, Clare L.; Ansell, David M.; Headon, Denis J.; Paus, Ralf

2016-01-01

Abstract The cutaneous healing response has evolved to occur rapidly, in order to minimize infection and to re‐establish epithelial homeostasis. Rapid healing is achieved through complex coordination of multiple cell types, which importantly includes specific cell populations within the hair follicle (HF). Under physiological conditions, the epithelial compartments of HF and interfollicular epidermis remain discrete, with K15+ve bulge stem cells contributing progeny for HF reconstruction during the hair cycle and as a basis for hair shaft production during anagen. Only upon wounding do HF cells migrate from the follicle to contribute to the neo‐epidermis. However, the identity of the first‐responding cells, and in particular whether this process involves a direct contribution of K15+ve bulge cells to the early stage of epidermal wound repair remains unclear. Here we demonstrate that epidermal injury in murine skin does not induce bulge activation during early epidermal wound repair. Specifically, bulge cells of uninjured HFs neither proliferate nor appear to migrate out of the bulge niche upon epidermal wounding. In support of these observations, Diphtheria toxin‐mediated partial ablation of K15+ve bulge cells fails to delay wound healing. Our data suggest that bulge cells only respond to epidermal wounding during later stages of repair. We discuss that this response may have evolved as a protective safeguarding mechanism against bulge stem cell exhaust and tumorigenesis. Stem Cells 2016;34:1377–1385 PMID:26756547

A Naturally Occurring Mutation in an Arabidopsis Accession Affects a β-d-Galactosidase That Increases the Hydrophilic Potential of Rhamnogalacturonan I in Seed Mucilage[W

PubMed Central

Macquet, Audrey; Ralet, Marie-Christine; Loudet, Olivier; Kronenberger, Jocelyne; Mouille, Gregory; Marion-Poll, Annie; North, Helen M.

2007-01-01

The Arabidopsis thaliana accession Shahdara was identified as a rare naturally occurring mutant that does not liberate seed mucilage on imbibition. The defective locus was found to be allelic to the mum2-1 and mum2-2 mutants. Map-based cloning showed that MUCILAGE-MODIFIED2 (MUM2) encodes the putative β-d-galactosidase BGAL6. Activity assays demonstrated that one of four major β-d-galactosidase activities present in developing siliques is absent in mum2 mutants. No difference was observed in seed coat epidermal cell structure between wild-type and mutant seed; however, weakening of the outer tangential cell wall by chemical treatment resulted in the release of mucilage from mum2 seed coat epidermal cells, and the mum2 mucilage only increased slightly in volume, relative to the wild type. Consistent with the absence of β-d-galactosidase activity in the mutant, the inner layer of mucilage contained more Gal. The allocation of polysaccharides between the inner and outer mucilage layers was also modified in mum2. Mass spectrometry showed that rhamnogalacturonan I in mutant mucilage had more branching between rhamnose and hexose residues relative to the wild type. We conclude that the MUM2/BGAL6 β-d-galactosidase is required for maturation of rhamnogalacturonan I in seed mucilage by the removal of galactose/galactan branches, resulting in increased swelling and extrusion of the mucilage on seed hydration. PMID:18165330

Epidermal Cadm1 expression promotes autoimmune alopecia via enhanced T cell adhesion and cytotoxicity.

PubMed

Giangreco, Adam; Hoste, Esther; Takai, Yoshimi; Rosewell, Ian; Watt, Fiona M

2012-02-01

Autoimmune alopecia is characterized by an extensive epidermal T cell infiltrate that mediates hair follicle destruction. We have investigated the role of cell adhesion molecule 1 (Cadm1; Necl2) in this disease. Cadm1 is expressed by epidermal cells and mediates heterotypic adhesion to lymphocytes expressing class 1-restricted T cell-associated molecule (CRTAM). Using a murine autoimmune alopecia model, we observed an increase in early-activated cytotoxic (CD8-restricted, CRTAM-expressing) T cells, which preferentially associated with hair follicle keratinocytes expressing Cadm1. Coculture with Cadm1-transduced MHC-matched APCs stimulated alopecic lymph node cells to release IL-2 and IFN-γ. Overexpression of Cadm1 in cultured human keratinocytes did not promote cytokine secretion, but led to increased adhesion of alopecic cytotoxic T cells and enhanced T cell cytotoxicity in an MHC-independent manner. Epidermal overexpression of Cadm1 in transgenic mice led to increased autoimmune alopecia susceptibility relative to nontransgenic littermate controls. Our findings reveal that Cadm1 expression in the hair follicle plays a role in autoimmune alopecia.

Immunocytolocalization of extensin in developing soybean seed coats by immunogold-silver staining and by tissue printing on nitrocellulose paper

PubMed Central

1987-01-01

In soybean seed coats the accumulation of the hydroxyproline-rich glycoprotein extensin is regulated in a developmental and tissue- specific manner. The time course of appearance of extensin during seed development was studied by Western blot analysis and by immunogold- silver localization. Using these techniques extensin was first detected at 16-18 d after anthesis, increasing during development to high levels at 24 d after anthesis. Immunogold-silver localization of extensin in the seed coat showed marked deposition of the glycoprotein in the walls of palisade epidermal cells and hourglass cells. The immunolocalization of extensin in developing soybean seeds was also made by a new technique--tissue printing on nitrocellulose paper. It was found that extensin is primarily localized in the seed coat, hilum, and vascular elements of the seed. PMID:3693394

Emission spectra profiling of fluorescent proteins in living plant cells

PubMed Central

2013-01-01

Background Fluorescence imaging at high spectral resolution allows the simultaneous recording of multiple fluorophores without switching optical filters, which is especially useful for time-lapse analysis of living cells. The collected emission spectra can be used to distinguish fluorophores by a computation analysis called linear unmixing. The availability of accurate reference spectra for different fluorophores is crucial for this type of analysis. The reference spectra used by plant cell biologists are in most cases derived from the analysis of fluorescent proteins in solution or produced in animal cells, although these spectra are influenced by both the cellular environment and the components of the optical system. For instance, plant cells contain various autofluorescent compounds, such as cell wall polymers and chlorophyll, that affect the spectral detection of some fluorophores. Therefore, it is important to acquire both reference and experimental spectra under the same biological conditions and through the same imaging systems. Results Entry clones (pENTR) of fluorescent proteins (FPs) were constructed in order to create C- or N-terminal protein fusions with the MultiSite Gateway recombination technology. The emission spectra for eight FPs, fused C-terminally to the A- or B-type cyclin dependent kinases (CDKA;1 and CDKB1;1) and transiently expressed in epidermal cells of tobacco (Nicotiana benthamiana), were determined by using the Olympus FluoView™ FV1000 Confocal Laser Scanning Microscope. These experimental spectra were then used in unmixing experiments in order to separate the emission of fluorophores with overlapping spectral properties in living plant cells. Conclusions Spectral imaging and linear unmixing have a great potential for efficient multicolor detection in living plant cells. The emission spectra for eight of the most commonly used FPs were obtained in epidermal cells of tobacco leaves and used in unmixing experiments. The generated set of FP Gateway entry vectors represents a valuable resource for plant cell biologists. PMID:23552272

Carbon Dioxide Metabolism in Leaf Epidermal Tissue 1

PubMed Central

Willmer, C. M.; Pallas, J. E.; Black, C. C.

1973-01-01

A number of plant species were surveyed to obtain pure leaf epidermal tissue in quantity. Commelina communis L. and Tulipa gesnariana L. (tulip) were chosen for further work. Chlorophyll a/b ratios of epidermal tissues were 2.41 and 2.45 for C. communis and tulip, respectively. Phosphoenolpyruvate carboxylase, ribulose-1,5-diphosphate carboxylase, malic enzyme, and NAD+ and NADP+ malate dehydrogenases were assayed with epidermal tissue and leaf tissue minus epidermal tissue. In both species, there was less ribulose 1,5-diphosphate than phosphoenolpyruvate carboxylase activity in epidermal tissue whether expressed on a protein or chlorophyll basis whereas the reverse was true for leaf tissue minus epidermal tissue. In both species, malic enzyme activities were higher in epidermal tissue than in the remaining leaf tissue when expressed on a protein or chlorophyll basis. In both species, NAD+ and NADP+ malate dehydrogenase activities were higher in the epidermal tissue when expressed on a chlorophyll basis; however, on a protein basis, the converse was true. Microautoradiography of C. communis epidermis and histochemical tests for keto acids suggested that CO2 fixation occurred predominantly in the guard cells. The significance and possible location of the enzymes are discussed in relation to guard cell metabolism. Images PMID:16658581

Rhizobium meliloti lipooligosaccharide nodulation factors: different structural requirements for bacterial entry into target root hair cells and induction of plant symbiotic developmental responses.

PubMed

Ardourel, M; Demont, N; Debellé, F; Maillet, F; de Billy, F; Promé, J C; Dénarié, J; Truchet, G

1994-10-01

Rhizobium meliloti produces lipochitooligosaccharide nodulation NodRm factors that are required for nodulation of legume hosts. NodRm factors are O-acetylated and N-acylated by specific C16-unsaturated fatty acids. nodL mutants produce non-O-acetylated factors, and nodFE mutants produce factors with modified acyl substituents. Both mutants exhibited a significantly reduced capacity to elicit infection thread (IT) formation in alfalfa. However, once initiated, ITs developed and allowed the formation of nitrogen-fixing nodules. In contrast, double nodF/nodL mutants were unable to penetrate into legume hosts and to form ITs. Nevertheless, these mutants induced widespread cell wall tip growth in trichoblasts and other epidermal cells and were also able to elicit cortical cell activation at a distance. NodRm factor structural requirements are thus clearly more stringent for bacterial entry than for the elicitation of developmental plant responses.

The targeted overexpression of a Claudin mutant in the epidermis of transgenic mice elicits striking epidermal and hair follicle abnormalities.

PubMed

Troy, Tammy-Claire; Turksen, Kursad

2007-06-01

Skin is one of the largest organs of the body, and is formed during development through a highly orchestrated process involving mesenchymal-epithelial interactions, cell commitment, and terminal differentiation. It protects against microorganism invasion and UV irradiation, inhibits water loss, regulates body temperature, and is an important part of the immune system. Using transgenic mouse technology, we have demonstrated that Claudin (Cldn)-containing tight junctions (TJs) are intricately involved in cell signaling during epidermal differentiation and that an epidermal suprabasal overexpression of Cldn6 results in a perturbed epidermal terminal differentiation program with distinct phenotypic abnormalities. To delineate the role of the Cldn cytoplasmic tail domain in epidermal differentiation, we engineered transgenic mice targeting the overexpression of a Cldn6 cytoplasmic tail-truncation mutant in the epidermis. Transgenic mice were characterized by a lethal barrier dysfunction in addition to the existence of hyperproliferative squamous invaginations/cysts replacing hair follicles. Immunohistochemical analysis revealed an epidermal cytoplasmic accumulation of Cldn6, Cldn11, Cldn12, and Cldn18, downregulation of Cldn1 and aberrant expression of various classical markers of epidermal differentiation; namely the basal keratins as well as K1, involucrin, loricrin, and filaggrin. Collectively these studies suggest an important role for Cldns in epidermal/hair follicle differentiation programs likely involving cross talk to signaling pathways (e.g., Notch) directing cell fate selection and differentiation.

Myosin II activity is required for functional leading-edge cells and closure of epidermal sheets in fish skin ex vivo.

PubMed

Morita, Toshiyuki; Tsuchiya, Akiko; Sugimoto, Masazumi

2011-09-01

Re-epithelialization in skin wound healing is a process in which epidermal sheets grow and close the wound. Although the actin-myosin system is thought to have a pivotal role in re-epithelialization, its role is not clear. In fish skin, re-epithelialization occurs around 500 μm/h and is 50 times faster than in mammalian skin. We had previously reported that leading-edge cells of the epidermal outgrowth have both polarized large lamellipodia and "purse string"-like actin filament cables in the scale-skin culture system of medaka fish, Oryzias latipes (Cell Tissue Res, 2007). The actin purse-string (APS) is a supracellular contractile machinery in which adherens junctions (AJs) link intracellular myosin II-including actin cables between neighboring cells. In this study, we developed a modified "face-to-face" scale-skin culture system as an ex vivo model to study epidermal wound healing, and examined the role of the actin-myosin system in the rapid re-epithelialization using a myosin II ATPase inhibitor, blebbistatin. A low level of blebbistatin suppressed the formation of APS and induced the dissociation of keratocytes from the leading edge without attenuating the growth of the epidermal sheet or the migration rate of solitary keratocytes. AJs in the superficial layer showed no obvious changes elicited by blebbistatin. However, two epidermal sheets without APSs did not make a closure with each other, which was confirmed by inhibiting the connecting AJs between the superficial layers. These results suggest that myosin II activity is required for functional leading-edge cells and for epidermal closure.

Epidermal Notch1 recruits RORγ(+) group 3 innate lymphoid cells to orchestrate normal skin repair.

PubMed

Li, Zhi; Hodgkinson, Tom; Gothard, Elizabeth J; Boroumand, Soulmaz; Lamb, Rebecca; Cummins, Ian; Narang, Priyanka; Sawtell, Amy; Coles, Jenny; Leonov, German; Reboldi, Andrea; Buckley, Christopher D; Cupedo, Tom; Siebel, Christian; Bayat, Ardeshir; Coles, Mark C; Ambler, Carrie A

2016-04-21

Notch has a well-defined role in controlling cell fate decisions in the embryo and the adult epidermis and immune systems, yet emerging evidence suggests Notch also directs non-cell-autonomous signalling in adult tissues. Here, we show that Notch1 works as a damage response signal. Epidermal Notch induces recruitment of immune cell subsets including RORγ(+) ILC3s into wounded dermis; RORγ(+) ILC3s are potent sources of IL17F in wounds and control immunological and epidermal cell responses. Mice deficient for RORγ(+) ILC3s heal wounds poorly resulting from delayed epidermal proliferation and macrophage recruitment in a CCL3-dependent process. Notch1 upregulates TNFα and the ILC3 recruitment chemokines CCL20 and CXCL13. TNFα, as a Notch1 effector, directs ILC3 localization and rates of wound healing. Altogether these findings suggest that Notch is a key stress/injury signal in skin epithelium driving innate immune cell recruitment and normal skin tissue repair.

Ephrin-Bs Drive Junctional Downregulation and Actin Stress Fiber Disassembly to Enable Wound Re-epithelialization

PubMed Central

Nunan, Robert; Campbell, Jessica; Mori, Ryoichi; Pitulescu, Mara E.; Jiang, Wen G.; Harding, Keith G.; Adams, Ralf H.; Nobes, Catherine D.; Martin, Paul

2015-01-01

Summary For a skin wound to successfully heal, the cut epidermal-edge cells have to migrate forward at the interface between scab and healthy granulation tissue. Much is known about how lead-edge cells migrate, but very little is known about the mechanisms that enable active participation by cells further back. Here we show that ephrin-B1 and its receptor EphB2 are both upregulated in vivo, just for the duration of repair, in the first 70 or so rows of epidermal cells, and this signal leads to downregulation of the molecular components of adherens and tight (but not desmosomal) junctions, leading to loosening between neighbors and enabling shuffle room among epidermal cells. Additionally, this signaling leads to the shutdown of actomyosin stress fibers in these same epidermal cells, which may act to release tension within the wound monolayer. If this signaling axis is perturbed, then disrupted healing is a consequence in mouse and man. PMID:26549443

[Epidermal cyst and osteolysis of the cranial vault].

PubMed

Guillaud, V; Rémond, J; Balme, B; Moulin, G

1992-01-01

In a 40-year old man undergoing, under local anaesthesia, excision of an epidermal cyst located in the frontal region, at the border of the scalp, the operator had difficulties in removing the deep part of the cyst and perceived an underlying bone depression. The depression was caused by a 2 x 1.3 cm wide lacuna in the calvarium, which was subsequently treated by neurosurgeons. Histology showed only fragments of a simple epidermal cyst wall and no evidence of dermoid cyst. The causes of osteolysis associated with congenital or acquired skin lesions are reviewed. In this case, the old age and volume of the cyst may explain the osteolysis by mechanical compression. This case is exceptional since we were unable to find other examples in the literature, apart from dermoid and trichilemmal cysts.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okano, Junko, E-mail: jokano@belle.shiga-med.ac.jp; Kojima, Hideto; Katagi, Miwako

Bone marrow-derived cells (BMDCs) can migrate into the various organs in the mice irradiated by ionizing radiation (IR). However, it may not be the case in the skin. While IR is used for bone marrow (BM) transplantation, studying with the epidermal sheets demonstrated that the BMDC recruitment is extraordinarily rare in epidermis in the mouse. Herein, using the chimera mice with BM from green fluorescent protein (GFP) transgenic mice, we simply examined if BMDCs migrate into any layers in the total skin, as opposed to the epidermal sheets, in response to IR. Interestingly, we identified the presence of GFP-positive (GFP{supmore » +}) cells in the epidermis-dermis junction in the total skin sections although the epidermal cell sheets failed to have any GFP cells. To examine a possibility that the cells in the junction could be mechanically dissociated during separating epidermal sheets, we then salvaged such dissociated cells and examined its characteristics. Surprisingly, some GFP{sup +} cells were found in the salvaged cells, indicating that these cells could be derived from BM. In addition, such BMDCs were also associated with inflammation in the junction. In conclusion, BMDCs can migrate to and reside in the epidermis-dermis junction after IR. - Highlights: • Bone marrow-derived cells (BMDCs) migrate in the epidermis due to ionizing radiation (IR). • BMDCs dissociate from the epidermis-dermis junction in preparing epidermal sheets. • The doses of IR determine the location and the number of migrating BMDCs in the skin.« less

Hair Follicle Bulge Stem Cells Appear Dispensable for the Acute Phase of Wound Re-epithelialization.

PubMed

Garcin, Clare L; Ansell, David M; Headon, Denis J; Paus, Ralf; Hardman, Matthew J

2016-05-01

The cutaneous healing response has evolved to occur rapidly, in order to minimize infection and to re-establish epithelial homeostasis. Rapid healing is achieved through complex coordination of multiple cell types, which importantly includes specific cell populations within the hair follicle (HF). Under physiological conditions, the epithelial compartments of HF and interfollicular epidermis remain discrete, with K15(+ve) bulge stem cells contributing progeny for HF reconstruction during the hair cycle and as a basis for hair shaft production during anagen. Only upon wounding do HF cells migrate from the follicle to contribute to the neo-epidermis. However, the identity of the first-responding cells, and in particular whether this process involves a direct contribution of K15(+ve) bulge cells to the early stage of epidermal wound repair remains unclear. Here we demonstrate that epidermal injury in murine skin does not induce bulge activation during early epidermal wound repair. Specifically, bulge cells of uninjured HFs neither proliferate nor appear to migrate out of the bulge niche upon epidermal wounding. In support of these observations, Diphtheria toxin-mediated partial ablation of K15(+ve) bulge cells fails to delay wound healing. Our data suggest that bulge cells only respond to epidermal wounding during later stages of repair. We discuss that this response may have evolved as a protective safeguarding mechanism against bulge stem cell exhaust and tumorigenesis. Stem Cells 2016;34:1377-1385. © 2016 The Authors. Stem Cells published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.

Niclosamide inhibits epithelial-mesenchymal transition and tumor growth in lapatinib-resistant human epidermal growth factor receptor 2-positive breast cancer.

PubMed

Liu, Junjun; Chen, Xiaosong; Ward, Toby; Mao, Yan; Bockhorn, Jessica; Liu, Xiaofei; Wang, Gen; Pegram, Mark; Shen, Kunwei

2016-02-01

Acquired resistance to lapatinib, a human epidermal growth factor receptor 2 kinase inhibitor, remains a clinical problem for women with human epidermal growth factor receptor 2-positive advanced breast cancer, as metastasis is commonly observed in these patients. Niclosamide, an anti-helminthic agent, has recently been shown to exhibit cytotoxicity to tumor cells with stem-like characteristics. This study was designed to identify the mechanisms underlying lapatinib resistance and to determine whether niclosamide inhibits lapatinib resistance by reversing epithelial-mesenchymal transition. Here, two human epidermal growth factor receptor 2-positive breast cancer cell lines, SKBR3 and BT474, were exposed to increasing concentrations of lapatinib to establish lapatinib-resistant cultures. Lapatinib-resistant SKBR3 and BT474 cells exhibited up-regulation of the phenotypic epithelial-mesenchymal transition markers Snail, vimentin and α-smooth muscle actin, accompanied by activation of nuclear factor-кB and Src and a concomitant increase in stem cell marker expression (CD44(high)/CD24(low)), compared to naive lapatinib-sensitive SKBR3 and BT474 cells, respectively. Interestingly, niclosamide reversed epithelial-mesenchymal transition, induced apoptosis and inhibited cell growth by perturbing aberrant signaling pathway activation in lapatinib-resistant human epidermal growth factor receptor 2-positive cells. The ability of niclosamide to alleviate stem-like phenotype development and invasion was confirmed. Collectively, our results demonstrate that lapatinib resistance correlates with epithelial-mesenchymal transition and that niclosamide inhibits lapatinib-resistant cell viability and epithelial-mesenchymal transition. These findings suggest a role of niclosamide or derivatives optimized for more favorable bioavailability not only in reversing lapatinib resistance but also in reducing metastatic potential during the treatment of human epidermal growth factor receptor 2-positive breast cancer. Copyright © 2015 Elsevier Ltd. All rights reserved.

Peeling off the genetics of atopic dermatitis-like congenital disorders.

PubMed

Samuelov, Liat; Sprecher, Eli

2014-10-01

The epidermis forms during the course of a complex differentiation process known as cornification, which culminates with the formation of the epidermal barrier. The epidermal barrier serves as a vital line of defense against the environment and mainly consists of 3 elements: intracellular keratin filaments, intercellular lipids, and the cornified cell envelope. Adequate epidermal barrier function is also critically dependent on normal shedding of terminally differentiated keratinocytes, a process termed desquamation, which requires the dissolution of cell-cell junctions in the upper granular layers. Although much has been learned about epidermal differentiation through the deciphering of the molecular basis of various cornification disorders, less is currently known about the mechanisms regulating epidermal desquamation and disorders resulting from disruption of this process. Netherton syndrome, peeling skin syndrome type B, and skin dermatitis--multiple severe allergies--metabolic wasting syndrome are 3 autosomal recessive conditions resulting from aberrant regulation of epidermal desquamation. The deciphering of their pathogenesis has not only broadened our understanding of this process but has also shed new light on clinical and mechanistic links between allergic reactions and abnormal desquamation, substantiating the notion that allergic manifestations might, under some circumstances, be the sole consequence of a primary epidermal defect. Copyright © 2014 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Histopathology of a mesoparasitic hatschekiid copepod in hospite: does Mihbaicola sakamakii (Copepoda: Siphonostomatoida: Hatschekiidae) fast within the host fish tissue?

PubMed

Hirose, Euichi; Uyeno, Daisuke

2014-08-01

Mihbaicola sakamakii is a mesoparasitic copepod that infests the branchiostegal membranes of groupers (Perciformes: Serranidae). In this study, we observed M. sakamakii within host tissue. Histologically, copepods were found enclosed inside a pouch composed of the thickened epidermis of the host, tightly encased on all sides by the host epidermal pouch wall. There were no host blood cells or other food resources in the pouch lumen. Since the host epidermis was intact and continuous, even in the vicinity of the oral region of the parasite, the copepod would not have access to the host blood in this state. However, the stomach (ampullary part of the mid gut) was filled with granular components, the majority of which were crystalloids that likely originated from fish erythrocyte hemoglobin. We supposed that the parasite drinks blood exuded from the lesion in the fish caused by copepod entry into the host tissue. Invasion of the parasite may elicit immune responses in the host, but there were no traces on the copepod of any cellular immune reactions, such as encapsulation. The array of minute protuberances on the copepod cuticle surface may be involved in avoidance of cell adhesion. After the lesion has healed, the copepod is enclosed in a tough epidermal pouch, in which it gradually digests the contents of its stomach and continues egg production.

Epidermal growth in the bottlenose dolphin, Tursiops truncatus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hicks, B.D.; St. Aubin, D.J.; Geraci, J.R.

1985-07-01

Epidermal growth in two mature female bottlenose dolphins, Tursiops truncatus, was investigated by following the movement of a cohort of tritiated thymidine-labeled epidermal cells for 59 days. The majority of the cells migrated in a cluster which was estimated to reach the skin surface in 73 days. The authors calculate that the outermost cell layer is sloughed 12 times per day. Turnover time and sloughing rate are estimated to be 1.7 times longer and 8.5 times faster than the respective values for epidermal cell kinetics in humans. This apparent inconsistency of slow transit time and rapid sloughing rate is reconciledmore » by the convoluted structure of the stratum germinativum in the dolphin which results in a ratio of germinatival to superficial cells of 876:1. The stratum germinativum of dolphin epidermis appears to lack morphologically distinct, spatially segregated subpopulations of anchoring and stem cells. Dolphin epidermis has a large capacity for cell population, relatively long turnover time, and rapid sloughing rate. The adaptive advantages of these characteristics are discussed.« less

Identification of a Population of Epidermal Squamous Cell Carcinoma Cells with Enhanced Potential for Tumor Formation

PubMed Central

Adhikary, Gautam; Grun, Dan; Kerr, Candace; Balasubramanian, Sivaprakasam; Rorke, Ellen A.; Vemuri, Mohan; Boucher, Shayne; Bickenbach, Jackie R.; Hornyak, Thomas; Xu, Wen; Fisher, Matthew L.; Eckert, Richard L.

2013-01-01

Epidermal squamous cell carcinoma is among the most common cancers in humans. These tumors are comprised of phenotypically diverse populations of cells that display varying potential for proliferation and differentiation. An important goal is identifying cells from this population that drive tumor formation. To enrich for tumor-forming cells, cancer cells were grown as spheroids in non-attached conditions. We show that spheroid-selected cells form faster growing and larger tumors in immune-compromised mice as compared to non-selected cells. Moreover, spheroid-selected cells gave rise to tumors following injection of as few as one hundred cells, suggesting these cells have enhanced tumor-forming potential. Cells isolated from spheroid-selected tumors retain an enhanced ability to grow as spheroids when grown in non-attached culture conditions. Thus, these tumor-forming cells retain their phenotype following in vivo passage as tumors. Detailed analysis reveals that spheroid-selected cultures are highly enriched for expression of epidermal stem cell and embryonic stem cell markers, including aldehyde dehydrogenase 1, keratin 15, CD200, keratin 19, Oct4, Bmi-1, Ezh2 and trimethylated histone H3. These studies indicate that a subpopulation of cells that possess stem cell-like properties and express stem cell markers can be derived from human epidermal cancer cells and that these cells display enhanced ability to drive tumor formation. PMID:24376802

Blumeria graminis interactions with barley conditioned by different single R genes demonstrate a temporal and spatial relationship between stomatal dysfunction and cell death.

PubMed

Prats, Elena; Gay, Alan P; Roberts, Peter C; Thomas, Barry J; Sanderson, Ruth; Paveley, Neil; Lyngkjaer, Michael F; Carver, Tim L W; Mur, Luis A J

2010-01-01

Hypersensitive response (HR) against Blumeria graminis f. sp. hordei infection in barley (Hordeum vulgare) was associated with stomata "lock-up" leading to increased leaf water conductance (g(l)). Unique spatio-temporal patterns of HR formation occurred in barley with Mla1, Mla3, or MlLa R genes challenged with B. graminis f. sp. hordei. With Mla1, a rapid HR, limited to epidermal cells, arrested fungal growth before colonies initiated secondary attacks. With Mla3, mesophyll HR preceded that in epidermal cells whose initial survival supported secondary infections. With MlLa, mesophyll survived and not all attacked epidermal cells died immediately, allowing colony growth and secondary infection until arrested. Isolines with Mla1, Mla3, or MlLa genes inoculated with B. graminis f. sp. hordei ranging from 1 to 100 conidia mm(2) showed abnormally high g(l) during dark periods whose timing and extent correlated with those of each HR. Each isoline showed increased dark g(l) with the nonpathogen B. graminis f. sp. avenae which caused a single epidermal cell HR. Guard cell autofluorescence was seen only after drying of epidermal strips and closure of stomata suggesting that locked open stomata were viable. The data link stomatal lock-up to HR associated cell death and has implications for strategies for selecting disease resistant genotypes.

Differentiated epidermal outgrowths in the planarian Dugesia gonocephala: a model for studying cell renewal and patterning in single-layered epithelial tissue.

PubMed

Chandebois, R

1985-01-01

Large deep wounds on the ventral side of a flatworm (Planaria) will not heal. Instead, the damage to the parenchyma in the wound's roof will result in a differentiated swelling in the dorsal epidermis, above the wound which will eventually disappear with the disintegration of the underlying damaged tissue and a ventrodorsal hole appears in place of the wound. The dorsal epidermal outgrowth is formed by a number of excrescences, the development of which involves four successive stages. Their analysis suggests that epidermal cells are continuously produced by their own stem cells which remain unnoticed because their nuclei are hardly stainable. The daughter cells differentiate without information from either the underlying tissues or the basal epithelial membrane. During the first stage of this differentiation the cells become ciliated and motile, with some embryonic features. They then produce rhabdites and take up a columnar shape as they may become attached to the basal membrane. After wound setting the production of epidermal cells increases and the overcrowding of the basal membrane results in (1) detachment of stem cells and motile ciliated cells from the basal tissues, i.e. outgrowths; (2) stretching of columnar cells at the base of the outgrowths. When in the process of tissue disintegration the basal membrane of the epithelium also disappears, the cells remain in a single-layered epithelial configuration and retain their original polarity. These results are at variance with the generally accepted hypothesis that, in planarians, epidermal cells originate from the parenchyma and the epidermis is not an autonomous tissue.

Skin Stem Cells: At the Frontier Between the Laboratory and Clinical Practice. Part 1: Epidermal Stem Cells.

PubMed

Pastushenko, I; Prieto-Torres, L; Gilaberte, Y; Blanpain, C

2015-11-01

Stem cells are characterized by their ability to self-renew and differentiate into the different cell lineages of their tissue of origin. The discovery of stem cells in adult tissues, together with the description of specific markers for their isolation, has opened up new lines of investigation, expanding the horizons of biomedical research and raising new hope in the treatment of many diseases. In this article, we review in detail the main characteristics of the stem cells that produce the specialized cells of the skin (epidermal, mesenchymal, and melanocyte stem cells) and their potential implications and applications in diseases affecting the skin. Part I deals with the principal characteristics and potential applications of epidermal stem cells in dermatology. Copyright © 2015 Elsevier España, S.L.U. and AEDV. All rights reserved.

Egr-5 is a post-mitotic regulator of planarian epidermal differentiation

PubMed Central

Tu, Kimberly C; Cheng, Li-Chun; TK Vu, Hanh; Lange, Jeffrey J; McKinney, Sean A; Seidel, Chris W; Sánchez Alvarado, Alejandro

2015-01-01

Neoblasts are an abundant, heterogeneous population of adult stem cells (ASCs) that facilitate the maintenance of planarian tissues and organs, providing a powerful system to study ASC self-renewal and differentiation dynamics. It is unknown how the collective output of neoblasts transit through differentiation pathways to produce specific cell types. The planarian epidermis is a simple tissue that undergoes rapid turnover. We found that as epidermal progeny differentiate, they progress through multiple spatiotemporal transition states with distinct gene expression profiles. We also identified a conserved early growth response family transcription factor, egr-5, that is essential for epidermal differentiation. Disruption of epidermal integrity by egr-5 RNAi triggers a global stress response that induces the proliferation of neoblasts and the concomitant expansion of not only epidermal, but also multiple progenitor cell populations. Our results further establish the planarian epidermis as a novel paradigm to uncover the molecular mechanisms regulating ASC specification in vivo. DOI: http://dx.doi.org/10.7554/eLife.10501.001 PMID:26457503

Morphometric analysis of epidermal differentiation in primary roots of Zea mays

NASA Technical Reports Server (NTRS)

Moore, R.; Smith, H. S.

1990-01-01

Epidermal differentiation in primary roots of Zea mays was divided into six cell types based on cellular shape and cytoplasmic appearance. These six cell types are: 1) apical protoderm, located at the tip of the root pole and characterized by periclinally flattened cells; 2) cuboidal protoderm, located approximately 230 microns from the root pole and characterized by cuboidal cells; 3) tabular epidermis, located approximately 450 microns from the root pole and characterized by anticlinally flattened cells; 4) cuboidal epidermis, located approximately 900 microns from the root pole and characterized by cuboidal cells having numerous small vacuoles; 5) vacuolate cuboidal epidermis, located approximately 1,500 microns from the root pole and characterized by cuboidal cells containing several large vacuoles; and 6) columnar epidermis, located approximately 2,200 microns from the root pole (i.e., at the beginning of the zone of elongation) and characterized by elongated cells. We also used stereology to quantify the cellular changes associated with epidermal differentiation. The quiescent center and the apical protoderm have significantly different ultrastructures. The relative volume of dictyosomes increases dramatically during the early stages of epidermal differentiation. This increase correlates inversely with the amount of coverage provided by the root cap and mucilage.

SHINE transcription factors act redundantly to pattern the archetypal surface of Arabidopsis flower organs.

PubMed

Shi, Jian Xin; Malitsky, Sergey; De Oliveira, Sheron; Branigan, Caroline; Franke, Rochus B; Schreiber, Lukas; Aharoni, Asaph

2011-05-01

Floral organs display tremendous variation in their exterior that is essential for organogenesis and the interaction with the environment. This diversity in surface characteristics is largely dependent on the composition and structure of their coating cuticular layer. To date, mechanisms of flower organ initiation and identity have been studied extensively, while little is known regarding the regulation of flower organs surface formation, cuticle composition, and its developmental significance. Using a synthetic microRNA approach to simultaneously silence the three SHINE (SHN) clade members, we revealed that these transcription factors act redundantly to shape the surface and morphology of Arabidopsis flowers. It appears that SHNs regulate floral organs' epidermal cell elongation and decoration with nanoridges, particularly in petals. Reduced activity of SHN transcription factors results in floral organs' fusion and earlier abscission that is accompanied by a decrease in cutin load and modified cell wall properties. SHN transcription factors possess target genes within four cutin- and suberin-associated protein families including, CYP86A cytochrome P450s, fatty acyl-CoA reductases, GSDL-motif lipases, and BODYGUARD1-like proteins. The results suggest that alongside controlling cuticular lipids metabolism, SHNs act to modify the epidermis cell wall through altering pectin metabolism and structural proteins. We also provide evidence that surface formation in petals and other floral organs during their growth and elongation or in abscission and dehiscence through SHNs is partially mediated by gibberellin and the DELLA signaling cascade. This study therefore demonstrates the need for a defined composition and structure of the cuticle and cell wall in order to form the archetypal features of floral organs surfaces and control their cell-to-cell separation processes. Furthermore, it will promote future investigation into the relation between the regulation of organ surface patterning and the broader control of flower development and biological functions.

SHINE Transcription Factors Act Redundantly to Pattern the Archetypal Surface of Arabidopsis Flower Organs

PubMed Central

Shi, Jian Xin; Malitsky, Sergey; De Oliveira, Sheron; Branigan, Caroline; Franke, Rochus B.; Schreiber, Lukas; Aharoni, Asaph

2011-01-01

Floral organs display tremendous variation in their exterior that is essential for organogenesis and the interaction with the environment. This diversity in surface characteristics is largely dependent on the composition and structure of their coating cuticular layer. To date, mechanisms of flower organ initiation and identity have been studied extensively, while little is known regarding the regulation of flower organs surface formation, cuticle composition, and its developmental significance. Using a synthetic microRNA approach to simultaneously silence the three SHINE (SHN) clade members, we revealed that these transcription factors act redundantly to shape the surface and morphology of Arabidopsis flowers. It appears that SHNs regulate floral organs' epidermal cell elongation and decoration with nanoridges, particularly in petals. Reduced activity of SHN transcription factors results in floral organs' fusion and earlier abscission that is accompanied by a decrease in cutin load and modified cell wall properties. SHN transcription factors possess target genes within four cutin- and suberin-associated protein families including, CYP86A cytochrome P450s, fatty acyl-CoA reductases, GSDL-motif lipases, and BODYGUARD1-like proteins. The results suggest that alongside controlling cuticular lipids metabolism, SHNs act to modify the epidermis cell wall through altering pectin metabolism and structural proteins. We also provide evidence that surface formation in petals and other floral organs during their growth and elongation or in abscission and dehiscence through SHNs is partially mediated by gibberellin and the DELLA signaling cascade. This study therefore demonstrates the need for a defined composition and structure of the cuticle and cell wall in order to form the archetypal features of floral organs surfaces and control their cell-to-cell separation processes. Furthermore, it will promote future investigation into the relation between the regulation of organ surface patterning and the broader control of flower development and biological functions. PMID:21637781

Beneficial Effects of the Genus Aloe on Wound Healing, Cell Proliferation, and Differentiation of Epidermal Keratinocytes

PubMed Central

Uda, Junki; Kubo, Hirokazu; Nakajima, Yuka; Goto, Arisa; Akaki, Junji; Yoshida, Ikuyo; Matsuoka, Nobuya; Hayakawa, Takao

2016-01-01

Aloe has been used as a folk medicine because it has several important therapeutic properties. These include wound and burn healing, and Aloe is now used in a variety of commercially available topical medications for wound healing and skin care. However, its effects on epidermal keratinocytes remain largely unclear. Our data indicated that both Aloe vera gel (AVG) and Cape aloe extract (CAE) significantly improved wound healing in human primary epidermal keratinocytes (HPEKs) and a human skin equivalent model. In addition, flow cytometry analysis revealed that cell surface expressions of β1-, α6-, β4-integrin, and E-cadherin increased in HPEKs treated with AVG and CAE. These increases may contribute to cell migration and wound healing. Treatment with Aloe also resulted in significant changes in cell-cycle progression and in increases in cell number. Aloe increased gene expression of differentiation markers in HPEKs, suggesting roles for AVG and CAE in the improvement of keratinocyte function. Furthermore, human skin epidermal equivalents developed from HPEKs with medium containing Aloe were thicker than control equivalents, indicating the effectiveness of Aloe on enhancing epidermal development. Based on these results, both AVG and CAE have benefits in wound healing and in treatment of rough skin. PMID:27736988

UV fluorescence excitation spectroscopy as a non-invasive predictor of epidermal proliferation and clinical performance of cosmetic formulations

NASA Astrophysics Data System (ADS)

Maidhof, Robert; Liebel, Frank; Hwang, Cheng; Ruvolo, Eduardo; Lyga, John

2017-02-01

The epidermis is the outermost layer of skin and is composed of cells primarily containing keratin. It consists of about ten layers of living cells (keratinocytes) and ten layers of dead cells (corneocytes). These cells are continually shed from the outside and replaced from the inside in a process called desquamation which is controlled by two biological events - proliferation and differentiation. One method to non-invasively study biological changes in the skin is using fluorescence excitation spectroscopy. Several characteristic excitation-emission peaks occur in skin that have been related to the epidermal and dermal composition. The magnitude of the peak that occurs at 295nm excitation (F295) has been linked to changes in skin proliferation, cell turnover, epidermal thickening, and skin aging. We hypothesize that changes in this fluorescent signal could be used to assess the potential activity of cosmetic anti-aging compounds to deliver a benefit to skin. Previous work with retinol and glycolic acid, two commonly used actives that effect epidermal proliferation and exfoliation, has demonstrated an increase in F295 (attributed to tryptophan excitation fluorescence). In this study we present the results of a placebo controlled study that aims to correlate changes in F295 with biological performance (epidermal thickening and Ki67 expression).

Biochemistry of epidermal stem cells.

PubMed

Eckert, Richard L; Adhikary, Gautam; Balasubramanian, Sivaprakasam; Rorke, Ellen A; Vemuri, Mohan C; Boucher, Shayne E; Bickenbach, Jackie R; Kerr, Candace

2013-02-01

The epidermis is an important protective barrier that is essential for maintenance of life. Maintaining this barrier requires continuous cell proliferation and differentiation. Moreover, these processes must be balanced to produce a normal epidermis. The stem cells of the epidermis reside in specific locations in the basal epidermis, hair follicle and sebaceous glands and these cells are responsible for replenishment of this tissue. A great deal of effort has gone into identifying protein epitopes that mark stem cells, in identifying stem cell niche locations, and in understanding how stem cell populations are related. We discuss these studies as they apply to understanding normal epidermal homeostasis and skin cancer. An assortment of stem cell markers have been identified that permit assignment of stem cells to specific regions of the epidermis, and progress has been made in understanding the role of these cells in normal epidermal homeostasis and in conditions of tissue stress. A key finding is the multiple stem cell populations exist in epidermis that give rise to different structures, and that multiple stem cell types may contribute to repair in damaged epidermis. Understanding epidermal stem cell biology is likely to lead to important therapies for treating skin diseases and cancer, and will also contribute to our understanding of stem cells in other systems. This article is part of a Special Issue entitled Biochemistry of Stem Cells. Copyright © 2012 Elsevier B.V. All rights reserved.

Genetic Ablation of CCAAT/Enhancer Binding Protein α in Epidermis Reveals Its Role in Suppression of Epithelial Tumorigenesis

PubMed Central

Loomis, Kari D.; Zhu, Songyun; Yoon, Kyungsil; Johnson, Peter F.; Smart, Robert C.

2013-01-01

CCAAT/enhancer binding protein y (C/EBPα) is a basic leucine zipper transcription factor that inhibits cell cycle progression and regulates differentiation in various cell types. C/EBPα is inactivated by mutation in acute myeloid leukemia (AML) and is considered a human tumor suppressor in AML. Although C/EBPα mutations have not been observed in malignancies other than AML, greatly diminished expression of C/EBPα occurs in numerous human epithelial cancers including lung, liver, endometrial, skin, and breast, suggesting a possible tumor suppressor function. However, direct evidence for C/EBPα as an epithelial tumor suppressor is lacking due to the absence of C/EBPα mutations in epithelial tumors and the lethal effect of C/EBPα deletion in mouse model systems. To examine the function of C/EBPα in epithelial tumor development, an epidermal-specific C/EBPα knockout mouse was generated. The epidermal-specific C/EBPα knockout mice survived and displayed no detectable abnormalities in epidermal keratinocyte proliferation, differentiation, or apoptosis, showing that C/EBPα is dispensable for normal epidermal homeostasis. In spite of this, the epidermal-specific C/EBPα knockout mice were highly susceptible to skin tumor development involving oncogenic Ras. These mice displayed decreased tumor latency and striking increases in tumor incidence, multiplicity, growth rate, and the rate of malignant progression. Mice hemizygous for C/EBPα displayed an intermediate-enhanced tumor phenotype. Our results suggest that decreased expression of C/EBPα contributes to deregulation of tumor cell proliferation. C/EBPα had been proposed to block cell cycle progression through inhibition of E2F activity. We observed that C/EBPα blocked Ras-induced and epidermal growth factor-induced E2F activity in keratinocytes and also blocked Ras-induced cell transformation and cell cycle progression. Our study shows that C/EBPα is dispensable for epidermal homeostasis and provides genetic evidence that C/EBPα is a suppressor of epithelial tumorigenesis. PMID:17638888

A novel DLX3-PKC integrated signaling network drives keratinocyte differentiation.

PubMed

Palazzo, Elisabetta; Kellett, Meghan D; Cataisson, Christophe; Bible, Paul W; Bhattacharya, Shreya; Sun, Hong-Wei; Gormley, Anna C; Yuspa, Stuart H; Morasso, Maria I

2017-04-01

Epidermal homeostasis relies on a well-defined transcriptional control of keratinocyte proliferation and differentiation, which is critical to prevent skin diseases such as atopic dermatitis, psoriasis or cancer. We have recently shown that the homeobox transcription factor DLX3 and the tumor suppressor p53 co-regulate cell cycle-related signaling and that this mechanism is functionally involved in cutaneous squamous cell carcinoma development. Here we show that DLX3 expression and its downstream signaling depend on protein kinase C α (PKCα) activity in skin. We found that following 12-O-tetradecanoyl-phorbol-13-acetate (TPA) topical treatment, DLX3 expression is significantly upregulated in the epidermis and keratinocytes from mice overexpressing PKCα by transgenic targeting (K5-PKCα), resulting in cell cycle block and terminal differentiation. Epidermis lacking DLX3 (DLX3cKO), which is linked to the development of a DLX3-dependent epidermal hyperplasia with hyperkeratosis and dermal leukocyte recruitment, displays enhanced PKCα activation, suggesting a feedback regulation of DLX3 and PKCα. Of particular significance, transcriptional activation of epidermal barrier, antimicrobial peptide and cytokine genes is significantly increased in DLX3cKO skin and further increased by TPA-dependent PKC activation. Furthermore, when inhibiting PKC activity, we show that epidermal thickness, keratinocyte proliferation and inflammatory cell infiltration are reduced and the PKC-DLX3-dependent gene expression signature is normalized. Independently of PKC, DLX3 expression specifically modulates regulatory networks such as Wnt signaling, phosphatase activity and cell adhesion. Chromatin immunoprecipitation sequencing analysis of primary suprabasal keratinocytes showed binding of DLX3 to the proximal promoter regions of genes associated with cell cycle regulation, and of structural proteins and transcription factors involved in epidermal differentiation. These results indicate that Dlx3 potentially regulates a set of crucial genes necessary during the epidermal differentiation process. Altogether, we demonstrate the existence of a robust DLX3-PKCα signaling pathway in keratinocytes that is crucial to epidermal differentiation control and cutaneous homeostasis.

A novel DLX3–PKC integrated signaling network drives keratinocyte differentiation

PubMed Central

Palazzo, Elisabetta; Kellett, Meghan D; Cataisson, Christophe; Bible, Paul W; Bhattacharya, Shreya; Sun, Hong-wei; Gormley, Anna C; Yuspa, Stuart H; Morasso, Maria I

2017-01-01

Epidermal homeostasis relies on a well-defined transcriptional control of keratinocyte proliferation and differentiation, which is critical to prevent skin diseases such as atopic dermatitis, psoriasis or cancer. We have recently shown that the homeobox transcription factor DLX3 and the tumor suppressor p53 co-regulate cell cycle-related signaling and that this mechanism is functionally involved in cutaneous squamous cell carcinoma development. Here we show that DLX3 expression and its downstream signaling depend on protein kinase C α (PKCα) activity in skin. We found that following 12-O-tetradecanoyl-phorbol-13-acetate (TPA) topical treatment, DLX3 expression is significantly upregulated in the epidermis and keratinocytes from mice overexpressing PKCα by transgenic targeting (K5-PKCα), resulting in cell cycle block and terminal differentiation. Epidermis lacking DLX3 (DLX3cKO), which is linked to the development of a DLX3-dependent epidermal hyperplasia with hyperkeratosis and dermal leukocyte recruitment, displays enhanced PKCα activation, suggesting a feedback regulation of DLX3 and PKCα. Of particular significance, transcriptional activation of epidermal barrier, antimicrobial peptide and cytokine genes is significantly increased in DLX3cKO skin and further increased by TPA-dependent PKC activation. Furthermore, when inhibiting PKC activity, we show that epidermal thickness, keratinocyte proliferation and inflammatory cell infiltration are reduced and the PKC-DLX3-dependent gene expression signature is normalized. Independently of PKC, DLX3 expression specifically modulates regulatory networks such as Wnt signaling, phosphatase activity and cell adhesion. Chromatin immunoprecipitation sequencing analysis of primary suprabasal keratinocytes showed binding of DLX3 to the proximal promoter regions of genes associated with cell cycle regulation, and of structural proteins and transcription factors involved in epidermal differentiation. These results indicate that Dlx3 potentially regulates a set of crucial genes necessary during the epidermal differentiation process. Altogether, we demonstrate the existence of a robust DLX3–PKCα signaling pathway in keratinocytes that is crucial to epidermal differentiation control and cutaneous homeostasis. PMID:28186503

WEREWOLF, a MYB-related protein in Arabidopsis, is a position-dependent regulator of epidermal cell patterning.

PubMed

Lee, M M; Schiefelbein, J

1999-11-24

The formation of the root epidermis of Arabidopsis provides a simple and elegant model for the analysis of cell patterning. A novel gene, WEREWOLF (WER), is described here that is required for position-dependent patterning of the epidermal cell types. The WER gene encodes a MYB-type protein and is preferentially expressed within cells destined to adopt the non-hair fate. Furthermore, WER is shown to regulate the position-dependent expression of the GLABRA2 homeobox gene, to interact with a bHLH protein, and to act in opposition to the CAPRICE MYB. These results suggest a simple model to explain the specification of the two root epidermal cell types, and they provide insight into the molecular mechanisms used to control cell patterning.

Role of epidermal stem cells in repair of partial-thickness burn injury after using Moist Exposed Burn Ointment (MEBO(®)) histological and immunohistochemical study.

PubMed

El-Hadidy, M R; El-Hadidy, A R; Bhaa, A; Asker, S A; Mazroa, S A

2014-04-01

Moist Exposed Burn Ointment (MEBO(®)) is widely used topical agent applied on skin burn. This study investigated the effect of MEBO topical application on activation and proliferation of epidermal stem cells through the immunohistochemical localization of cytokeratin 19 (CK19) as a known marker expressed in epidermal stem cells. Biopsies from normal skin and burn wounds were taken from 21 patients with partial thickness burn 1, 4, 7, 14, 21, and 28 days after treatment with MEBO. Tissue sections were prepared for histological study and for CK19 immunohistochemical localization. In control skin, only few cells showed a positive CK19 immune-reaction. Burned skin showed necrosis of full thickness epidermis that extended to dermis. Gradual regeneration of skin accompanied with an enhancement in CK19 immune-reactivity was noted 4, 7, 14 and 21 days after treatment with MEBO. On day 28, a complete regeneration of skin was observed with a return of CK19 immune-reactivity to the basal pattern again. In conclusion, the enhancement of epidermal stem cell marker CK19 after treatment of partial thickness burn injuries with MEBO suggested the role of MEBO in promoting epidermal stem cell activation and proliferation during burn wound healing. Copyright © 2014 Elsevier Ltd. All rights reserved.

Increased symplasmic permeability in barley root epidermal cells correlates with defects in root hair development

PubMed Central

Marzec, M; Muszynska, A; Melzer, M; Sas-Nowosielska, H; Kurczynska, E U; Wick, S

2014-01-01

It is well known that the process of plant cell differentiation depends on the symplasmic isolation of cells. Before starting the differentiation programme, the individual cell or group of cells should restrict symplasmic communication with neighbouring cells. We tested the symplasmic communication between epidermal cells in the different root zones of parental barley plants Hordeum vulgare L., cv. ‘Karat’ with normal root hair development, and two root hairless mutants (rhl1.a and rhl1.b). The results clearly show that symplasmic communication was limited during root hair differentiation in the parental variety, whereas in both root hairless mutants epidermal cells were still symplasmically connected in the corresponding root zone. This paper is the first report on the role of symplasmic isolation in barley root cell differentiation, and additionally shows that a disturbance in the restriction of symplasmic communication is present in root hairless mutants. PMID:23927737

Apoptosis as a Mechanism for Keratinocyte Death in Canine Toxic Epidermal Necrolysis.

PubMed

Banovic, F; Dunston, S; Linder, K E; Rakich, P; Olivry, T

2017-03-01

In humans and dogs, toxic epidermal necrolysis (TEN) is a life-threatening dermatosis characterized by sudden epidermal death resulting in extensive skin detachment. There is little information on the pathogenesis of keratinocyte cell death in canine TEN. We studied the occurrence of apoptosis in skin lesions of dogs with TEN to determine if apoptosis contributes to the pathogenesis of this disease. Immunostaining with antibodies to activated caspase-3 and the terminal deoxynucleotidyl-transferase (TdT)-mediated deoxyuridine triphosphate (dUTP) nick-end labeling technique revealed positive apoptotic keratinocytes in basal and suprabasal epidermal compartments in 17 biopsy specimens collected from 3 dogs with TEN and 16 from 3 dogs with erythema multiforme (EM). There was no significant difference in the number of positively stained epidermal cells between TEN and EM. These results suggest that apoptosis of epidermal keratinocytes and lymphocytic satellitosis represent one of the early steps in the pathogenesis of canine TEN, as in the human disease counterpart.

Role of Pin1 in UVA-induced cell proliferation and malignant transformation in epidermal cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Chang Yeob; Hien, Tran Thi; Lim, Sung Chul

2011-06-24

Highlights: {yields} Pin1 expression is enhanced by low energy UVA irradiation in both skin tissues of hairless mice and JB6 C141 epidermal cells. {yields} UVA irradiation increases activator protein-1 activity and cyclin D1 in a Pin1-dependent manner. {yields} UVA potentiates EGF-inducible, anchorage-independent growth of epidermal cells, and this is suppressed by Pin1 inhibition or by anti-oxidant. -- Abstract: Ultraviolet A (UVA) radiation ({lambda} = 320-400 nm) is considered a major cause of human skin cancer. Pin1, a peptidyl prolyl isomerase, is overexpressed in most types of cancer tissues and plays an important role in cell proliferation and transformation. Here, wemore » demonstrated that Pin1 expression was enhanced by low energy UVA (300-900 mJ/cm{sup 2}) irradiation in both skin tissues of hairless mice and JB6 C141 epidermal cells. Exposure of epidermal cells to UVA radiation increased cell proliferation and cyclin D1 expression, and these changes were blocked by Pin1 inhibition. UVA irradiation also increased activator protein-1 (AP-1) minimal reporter activity and nuclear levels of c-Jun, but not c-Fos, in a Pin1-dependent manner. The increases in Pin1 expression and in AP-1 reporter activity in response to UVA were abolished by N-acetylcysteine (NAC) treatment. Finally, we found that pre-exposure of JB6 C141 cells to UVA potentiated EGF-inducible, anchorage-independent growth, and this effect was significantly suppressed by Pin1inhibition or by NAC.« less

Biochemistry of epidermal stem cells☆

PubMed Central

Eckert, Richard L.; Adhikary, Gautam; Balasubramanian, Sivaprakasam; Rorke, Ellen A.; Vemuri, Mohan C.; Boucher, Shayne E.; Bickenbach, Jackie R.; Kerr, Candace

2014-01-01

Background The epidermis is an important protective barrier that is essential for maintenance of life. Maintaining this barrier requires continuous cell proliferation and differentiation. Moreover, these processes must be balanced to produce a normal epidermis. The stem cells of the epidermis reside in specific locations in the basal epidermis, hair follicle and sebaceous glands and these cells are responsible for replenishment of this tissue. Scope of review A great deal of effort has gone into identifying protein epitopes that mark stem cells, in identifying stem cell niche locations, and in understanding how stem cell populations are related. We discuss these studies as they apply to understanding normal epidermal homeostasis and skin cancer. Major conclusions An assortment of stem cell markers have been identified that permit assignment of stem cells to specific regions of the epidermis, and progress has been made in understanding the role of these cells in normal epidermal homeostasis and in conditions of tissue stress. A key finding is the multiple stem cell populations exist in epidermis that give rise to different structures, and that multiple stem cell types may contribute to repair in damaged epidermis. General significance Understanding epidermal stem cell biology is likely to lead to important therapies for treating skin diseases and cancer, and will also contribute to our understanding of stem cells in other systems. This article is part of a Special Issue entitled Biochemistry of Stem Cells. PMID:22820019

The Caenorhabditis elegans Ephrin EFN-4 Functions Non-cell Autonomously with Heparan Sulfate Proteoglycans to Promote Axon Outgrowth and Branching

PubMed Central

Schwieterman, Alicia A.; Steves, Alyse N.; Yee, Vivian; Donelson, Cory J.; Bentley, Melissa R.; Santorella, Elise M.; Mehlenbacher, Taylor V.; Pital, Aaron; Howard, Austin M.; Wilson, Melissa R.; Ereddia, Danielle E.; Effrein, Kelsie S.; McMurry, Jonathan L.; Ackley, Brian D.; Chisholm, Andrew D.; Hudson, Martin L.

2016-01-01

The Eph receptors and their cognate ephrin ligands play key roles in many aspects of nervous system development. These interactions typically occur within an individual tissue type, serving either to guide axons to their terminal targets or to define boundaries between the rhombomeres of the hindbrain. We have identified a novel role for the Caenorhabditis elegans ephrin EFN-4 in promoting primary neurite outgrowth in AIY interneurons and D-class motor neurons. Rescue experiments reveal that EFN-4 functions non-cell autonomously in the epidermis to promote primary neurite outgrowth. We also find that EFN-4 plays a role in promoting ectopic axon branching in a C. elegans model of X-linked Kallmann syndrome. In this context, EFN-4 functions non-cell autonomously in the body-wall muscle and in parallel with HS modification genes and HSPG core proteins. This is the first report of an epidermal ephrin providing a developmental cue to the nervous system. PMID:26645816

Dermal-epidermal membrane systems by using human keratinocytes and mesenchymal stem cells isolated from dermis.

PubMed

Salerno, Simona; Messina, Antonietta; Giordano, Francesca; Bader, Augustinus; Drioli, Enrico; De Bartolo, Loredana

2017-02-01

Dermal-epidermal membrane systems were developed by co-culturing human keratinocytes with Skin derived Stem Cells (SSCs), which are Mesenchymal Stem Cells (MSCs) isolated from dermis, on biodegradable membranes of chitosan (CHT), polycaprolactone (PCL) and a polymeric blend of CHT and PCL. The membranes display physico-chemical, morphological, mechanical and biodegradation properties that could satisfy and fulfil specific requirements in skin tissue engineering. CHT membrane exhibits an optimal biodegradation rate for acute wounds; CHT-PCL for the chronic ones. On the other hand, PCL membrane in spite of its very slow biodegradation rate exhibits mechanical properties similar to in vivo dermis, a lower hydrophilic character, and a surface roughness, all properties that make it able to sustain cell adhesion and proliferation for in vitro skin models. Both CHT-PCL and PCL membranes guided epidermal and dermal differentiation of SSCs as pointed out by the expression of cytokeratins and the deposition of the ECM protein fibronectin, respectively. In the dermal-epidermal membrane systems, a more suitable microenvironment for the SSCs differentiation was promoted by the interactions and the mutual interplay with keratinocytes. Being skin tissue-biased stem cells committed to their specific final dermal and/or epidermal cell differentiation, SSCs are more suitable for skin tissue engineering than other adult MSCs with different origin. For this reason, they represent a useful autologous cell source for engineering skin substitutes for both in vivo and in vitro applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Investigation of viability of plant tissue in the environmental scanning electron microscopy.

PubMed

Zheng, Tao; Waldron, K W; Donald, Athene M

2009-11-01

The advantages of environmental scanning electron microscopy (ESEM) make it a suitable technique for studying plant tissue in its native state. There have been few studies on the effects of ESEM environment and beam damage on the viability of plant tissue. A simple plant tissue, Allium cepa (onion) upper epidermal tissue was taken as the model for study. The change of moisture content of samples was studied at different relative humidities. Working with the electron beam on, viability tests were conducted for samples after exposure in the ESEM under different operating conditions to investigate the effect of electron beam dose on the viability of samples. The results suggested that without the electron beam, the ESEM chamber itself can prevent the loss of initial moisture if its relative humidity is maintained above 90%. With the electron beam on, the viability of Allium cepa (onion) cells depends both on the beam accelerating voltage and the electron dose/unit area hitting the sample. The dose can be controlled by several of the ESEM instrumental parameters. The detailed process of beam damage on cuticle-down and cuticle-up samples was investigated and compared. The results indicate that cuticular adhesion to the cell wall is relatively weak, but highly resistant to electron beam damage. Systematic study on the effect of ESEM operation parameters has been done. Results qualitatively support the intuitive expectations, but demonstrate quantitatively that Allium cepa epidermal cells are able to be kept in a hydrated and viable state under relevant operation condition inside ESEM, providing a basis for further in situ experiments on plant tissues.

Evolution of petal epidermal micromorphology in Leguminosae and its use as a marker of petal identity.

PubMed

Ojeda, Isidro; Francisco-Ortega, Javier; Cronk, Quentin C B

2009-11-01

The legume flower is highly variable in symmetry and differentiation of petal types. Most papilionoid flowers are zygomorphic with three types of petals: one dorsal, two lateral and two ventral petals. Mimosoids have radial flowers with reduced petals while caesalpinioids display a range from strongly zygomorphic to nearly radial symmetry. The aims are to characterize the petal micromorphology relative to flower morphology and evolution within the family and assess its use as a marker of petal identity (whether dorsal, lateral or ventral) as determined by the expression of developmental genes. Petals were analysed using the scanning electron microscope and light microscope. A total of 175 species were studied representing 26 tribes and 89 genera in all three subfamilies of the Leguminosae. The papilionoids have the highest degree of variation of epidermal types along the dorsiventral axis within the flower. In Loteae and genistoids, in particular, it is common for each petal type to have a different major epidermal micromorphology. Papillose conical cells are mainly found on dorsal and lateral petals. Tabular rugose cells are mainly found on lateral petals and tabular flat cells are found only in ventral petals. Caesalpinioids lack strong micromorphological variation along this axis and usually have only a single major epidermal type within a flower, although the type maybe either tabular rugose cells, papillose conical cells or papillose knobby rugose cells, depending on the species. Strong micromorphological variation between different petals in the flower is exclusive to the subfamily Papilionoideae. Both major and minor epidermal types can be used as micromorphological markers of petal identity, at least in papilionoids, and they are important characters of flower evolution in the whole family. The molecular developmental pathway between specific epidermal micromorphology and the expression of petal identity genes has yet to be established.

Dermal matrix proteins initiate re-epithelialization but are not sufficient for coordinated epidermal outgrowth in a new fish skin culture model.

PubMed

Matsumoto, Reiko; Sugimoto, Masazumi

2007-02-01

We have established a new culture system to study re-epithelialization during fish epidermal wound healing. In this culture system, fetal bovine serum (FBS) stimulates the epidermal outgrowth of multi-cellular layers from scale skin mounted on a coverslip, even when cell proliferation is blocked. The rate of outgrowth is about 0.4 mm/h, and at 3 h after incubation, the area occupied by the epidermal sheet is nine times larger than the area of the original scale skin. Cells at the bottom of the outgrowth show a migratory phenotype with lamellipodia, and "purse string"-like actin bundles have been found over the leading-edge cells with polarized lamellipodia. In the superficial cells, re-development of adherens junctions and microridges has been detected, together with the appearance and translocation of phosphorylated p38 MAPK into nuclear areas. Thus, this culture system provides an excellent model to study the mechanisms of epidermal outgrowth accompanied by migration and re-differentiation. We have also examined the role of extracellular matrix proteins in the outgrowth. Type I collagen or fibronectin stimulates moderate outgrowth in the absence of FBS, but development of microridges and the distribution of phosphorylated p38 MAPK are attenuated in the superficial cells. In addition, the leading-edge cells do not have apparent "purse string"-like actin bundles. The outgrowth stimulated by FBS is inhibited by laminin. These results suggest that dermal substrates such as type I collagen and fibronectin are able to initiate epidermal outgrowth but require other factors to enhance such outgrowth, together with coordinated alterations in cellular phenotype.

Real-time visualization of macromolecule uptake by epidermal Langerhans cells in living animals.

PubMed

Frugé, Rachel E; Krout, Colleen; Lu, Ran; Matsushima, Hironori; Takashima, Akira

2012-03-01

As a skin-resident member of the dendritic cell family, Langerhans cells (LCs) are generally regarded to function as professional antigen-presenting cells. Here we report a simple method to visualize the endocytotic activity of LCs in living animals. BALB/c mice received subcutaneous injection of FITC-conjugated dextran (DX) probes into the ear skin and were then examined under confocal microscopy. Large numbers of FITC(+) epidermal cells became detectable 12-24 hours after injection as background fluorescence signals began to disappear. Most (>90%) of the FITC(+) epidermal cells expressed Langerin, and >95% of Langerin(+) epidermal cells exhibited significant FITC signals. To assess intracellular localization, Alexa Fluor 546-conjugated DX probes were locally injected into IAβ-enhanced green fluorescent protein (EGFP) knock-in mice and Langerin-EGFP-diphtheria toxin receptor mice--three dimensional rotation images showed close association of most of the internalized DX probes with major histocompatibility complex (MHC) class II molecules, but not with Langerin molecules. These observations support the current view that LCs constantly sample surrounding materials, including harmful and innocuous antigens, at the environmental interface. Our data also validate the potential utility of the newly developed imaging approach to monitor LC function in wild-type animals.

Structural variations among monocot emergent and amphibious species from lakes of the semi-arid region of Bahia, Brazil.

PubMed

Leite, K R B; França, F; Scatena, V I

2012-02-01

Temporary lakes are common in the semi-arid region of the State of Bahia and form water mirrors in the rainy season. In this period, various vegetal species appear having different life forms adapted to the seasonality conditions of the rainfall regime. This work surveyed the adaptive anatomical structures of some emergent and amphibious monocot species occurring in these lakes. We studied the anatomy of roots, rhizomes, leaves and scapes of Cyperus odoratus, Oxycaryum cubense, Pycreus macrostachyos (Cyperaceae) - amphibious species; and of Echinodorus grandiflorus (Alismataceae), Eichhornia paniculata (Pontederiaceae) and Habenaria repens (Orchidaceae) - emergent species. The anatomical features of the dermal, fundamental and vascular systems confirming the tendency of the adaptive convergence of these plants to temporary lacustrine the environment include: single layered epidermal cells with a thin cuticle layer in the aerial organs; the presence of air canals in all the organs; few or no supporting tissues; and less numerous conducting elements and thinner cell walls in the xylem. The reduction of the supporting tissues, the number of stomata, which can even be absent, and the number of conducting elements and the degree of cell wall lignification in the xylem of the emergent species is more accentuated than that of the amphibious species. The pattern of distribution of aerenchyma in the roots of the studied species was considered important to distinguish between amphibious and emergent life forms.

[Sporangia ontogeny and sporogenesis of the lycopodium Huperzia brevifolia (Lycopodiaceae) from the high mountains of Colombia].

PubMed

Barón, Edgar Javier Rincón; Landazábal, Leidy Vivivana Gélvez; Ballesteros, Helkin Giovany Forero; Prieto, Dagoberto Arrieta; Hleap, José Sergio

2009-12-01

Huperzia brevifolia is one of the dominant species of the genus Huperzia living in paramos and superparamos from the Colombian Andes. A detailed study of the sporangium's ontogeny and sporogenesis was carried out using specimens collected at 4200m above sea level, in Parque Natural Nacional El Cocuy, Colombia. Small pieces of caulinar axis bearing sporangia were fixed, dehydrated, paraffin embedded, sectioned in a rotatory microtome, and stained using the common Safranin O-Fast Green technique; handmade cross sections were also made, stained with aqueous Toluidine Blue (TBO). The sporangia develops basipetally, a condition that allows observation of all the developmental stages taking place throughout the caulinar axis of adult plants. Each sporangium originates from a group of epidermal cells, axilar to the microphylls. These cells undergo active mitosis, and produce new external and internal cellular groups. The sporangium wall and the tapetum originate from the external group of cells, while the internal cellular group leads to the sporogenous tissue. Meiosis occur in the sporocytes and produce simultaneous types tetrads, each one giving rise four trilete spores, with foveolate ornamentation. During the sporangium ripening, the outermost layer of the wall develops anticlinally, and inner periclinal thickenings and the innermost one perform as a secretory tapetum, which persists until the spores are completely mature. All other cellular layers colapse.

From structure to function - a family portrait of plant subtilases.

PubMed

Schaller, Andreas; Stintzi, Annick; Rivas, Susana; Serrano, Irene; Chichkova, Nina V; Vartapetian, Andrey B; Martínez, Dana; Guiamét, Juan J; Sueldo, Daniela J; van der Hoorn, Renier A L; Ramírez, Vicente; Vera, Pablo

2018-05-01

Contents Summary 901 I. Introduction 901 II. Biochemistry and structure of plant SBTs 902 III. Phylogeny of plant SBTs and family organization 903 IV. Physiological roles of plant SBTs 905 V. Conclusions and outlook 911 Acknowledgements 912 References 912 SUMMARY: Subtilases (SBTs) are serine peptidases that are found in all three domains of life. As compared with homologs in other Eucarya, plant SBTs are more closely related to archaeal and bacterial SBTs, with which they share many biochemical and structural features. However, in the course of evolution, functional diversification led to the acquisition of novel, plant-specific functions, resulting in the present-day complexity of the plant SBT family. SBTs are much more numerous in plants than in any other organism, and include enzymes involved in general proteolysis as well as highly specific processing proteases. Most SBTs are targeted to the cell wall, where they contribute to the control of growth and development by regulating the properties of the cell wall and the activity of extracellular signaling molecules. Plant SBTs affect all stages of the life cycle as they contribute to embryogenesis, seed development and germination, cuticle formation and epidermal patterning, vascular development, programmed cell death, organ abscission, senescence, and plant responses to their biotic and abiotic environments. In this article we provide a comprehensive picture of SBT structure and function in plants. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Tumor formation initiated by nondividing epidermal cells via an inflammatory infiltrate.

PubMed

Arwert, Esther N; Lal, Rohit; Quist, Sven; Rosewell, Ian; van Rooijen, Nico; Watt, Fiona M

2010-11-16

In mammalian epidermis, integrin expression is normally confined to the basal proliferative layer that contains stem cells. However, in epidermal hyperproliferative disorders and tumors, integrins are also expressed by suprabasal cells, with concomitant up-regulation of Erk mitogen-activated protein kinase (MAPK) signaling. In transgenic mice, expression of activated MAPK kinase 1 (MEK1) in the suprabasal, nondividing, differentiated cell layers (InvEE transgenics) results in epidermal hyperproliferation and skin inflammation. We now demonstrate that wounding induces benign tumors (papillomas and keratoacanthomas) in InvEE mice. By generating chimeras between InvEE mice and mice that lack the MEK1 transgene, we demonstrate that differentiating, nondividing cells that express MEK1 stimulate adjacent transgene-negative cells to divide and become incorporated into the tumor mass. Dexamethasone treatment inhibits tumor formation, suggesting that inflammation is involved. InvEE skin and tumors express high levels of IL1α; treatment with an IL1 receptor antagonist delays tumor onset and reduces incidence. Depletion of γδ T cells and macrophages also reduces tumor incidence. Because a hallmark of cancer is uncontrolled proliferation, it is widely assumed that tumors arise only from dividing cells. In contrast, our studies show that differentiated epidermal cells can initiate tumor formation without reacquiring the ability to divide and that they do so by triggering an inflammatory infiltrate.

Epidermal lipid in several cetacean species: ultrastructural observations.

PubMed

Pfeiffer, C J; Jones, F M

1993-09-01

The ultrastructure of the skin of four cetacean species, bottlenose dolphin (Tursiops truncatus) long-finned pilot whale (Globicephala melaena), humpback whale (Megaptera novaeangliae), and fin whale (Balaenoptera physalus) was investigated with particular reference to epidermal lipid. It has already been established that massive lipid reservoirs exist in whales, that the biochemical structures of cetacean lipids are unique, and that unusual intracellular lipid droplets appear in the epidermis. We report here some novel findings on scanning electron microscopic morphology of epidermal lipid, and on its ultrastructural morphology in general and specialized integumentary sites, including species not previously investigated. The intracellular epidermal lipid droplets were more extensive than lamellar body-derived intercellular lipid which is within the interstices of stratum externum cells. The intracellular droplets were spherical, highly variable in size ranging from 0.24 micron to 3.0 microns in diameter, appeared singly or were aggregated in cytoplasmic cavitations, and often were closely associated with epidermal cell nuclei. Evidence for exocytosis of the intracellular droplets was not observed. Significant numbers of intracellular lipid droplets are not observed in the epidermis of terrestrial mammals, so their presence is one of several aquatic specializations of the cetacean integument. Its full significance remains obscure, but it is more probably associated with epidermal cell metabolism than with secretion of lipid.

Cytoplasmic poly (A)-binding protein critically regulates epidermal maintenance and turnover in the planarian Schmidtea mediterranea.

PubMed

Bansal, Dhiru; Kulkarni, Jahnavi; Nadahalli, Kavana; Lakshmanan, Vairavan; Krishna, Srikar; Sasidharan, Vidyanand; Geo, Jini; Dilipkumar, Shilpa; Pasricha, Renu; Gulyani, Akash; Raghavan, Srikala; Palakodeti, Dasaradhi

2017-09-01

Identifying key cellular events that facilitate stem cell function and tissue organization is crucial for understanding the process of regeneration. Planarians are powerful model system to study regeneration and stem cell (neoblast) function. Here, using planaria, we show that the initial events of regeneration, such as epithelialization and epidermal organization are critically regulated by a novel cytoplasmic poly A-binding protein, SMED-PABPC2. Knockdown of smed-pabpc2 leads to defects in epidermal lineage specification, disorganization of epidermis and ECM, and deregulated wound healing, resulting in the selective failure of neoblast proliferation near the wound region. Polysome profiling suggests that epidermal lineage transcripts, including zfp-1 , are translationally regulated by SMED-PABPC2 . Together, our results uncover a novel role for SMED-PABPC2 in the maintenance of epidermal and ECM integrity, critical for wound healing and subsequent processes for regeneration. © 2017. Published by The Company of Biologists Ltd.

Intracellular processing of epidermal growth factor. I. Acidification of 125I-epidermal growth factor in intracellular organelles.

PubMed

Matrisian, L M; Planck, S R; Magun, B E

1984-03-10

We previously reported that 125I-labeled epidermal growth factor is processed intracellularly to acidic macromolecules in Rat-1 fibroblasts. The present study defines the precursor-product relationship and localization of the processing steps to subcellular organelles by the use of a single isoelectric species of 125I-epidermal growth factor and Percoll gradient fractionation. The native pI 4.55 125I-epidermal growth factor was rapidly processed to a pI 4.2 species on or near the cell surface and in organelles corresponding to clathrin-coated vesicles, Golgi, and endoplasmic reticulum. This species was then processed to a pI 4.35 species in similar organelles. The pI 4.2 and 4.35 species were converted to a pI 4.0 species in dense, lysosome-like organelles. This species was ultimately degraded and exocytosed from the cell as low molecular weight products.

Cytoplasmic poly (A)-binding protein critically regulates epidermal maintenance and turnover in the planarian Schmidtea mediterranea

PubMed Central

Bansal, Dhiru; Kulkarni, Jahnavi; Nadahalli, Kavana; Lakshmanan, Vairavan; Krishna, Srikar; Sasidharan, Vidyanand; Dilipkumar, Shilpa; Gulyani, Akash; Raghavan, Srikala

2017-01-01

Identifying key cellular events that facilitate stem cell function and tissue organization is crucial for understanding the process of regeneration. Planarians are powerful model system to study regeneration and stem cell (neoblast) function. Here, using planaria, we show that the initial events of regeneration, such as epithelialization and epidermal organization are critically regulated by a novel cytoplasmic poly A-binding protein, SMED-PABPC2. Knockdown of smed-pabpc2 leads to defects in epidermal lineage specification, disorganization of epidermis and ECM, and deregulated wound healing, resulting in the selective failure of neoblast proliferation near the wound region. Polysome profiling suggests that epidermal lineage transcripts, including zfp-1, are translationally regulated by SMED-PABPC2. Together, our results uncover a novel role for SMED-PABPC2 in the maintenance of epidermal and ECM integrity, critical for wound healing and subsequent processes for regeneration. PMID:28807897

Specific binding of Clostridium perfringens enterotoxin fragment to Claudin-b and modulation of zebrafish epidermal barrier.

PubMed

Zhang, Jingjing; Ni, Chen; Yang, Zhenguo; Piontek, Anna; Chen, Huapu; Wang, Sijie; Fan, Yiming; Qin, Zhihai; Piontek, Joerg

2015-08-01

Claudins (Cldn) are the major components of tight junctions (TJs) sealing the paracellular cleft in tissue barriers of various organs. Zebrafish Cldnb, the homolog of mammalian Cldn4, is expressed at epithelial cell-cell contacts and is important for regulating epidermal permeability. The bacterial toxin Clostridium perfringens enterotoxin (CPE) has been shown to bind to a subset of mammalian Cldns. In this study, we used the Cldn-binding C-terminal domain of CPE (194-319 amino acids, cCPE 194-319 ) to investigate its functional role in modulating zebrafish larval epidermal barriers. In vitro analyses show that cCPE 194-319 removed Cldn4 from epithelial cells and disrupted the monolayer tightness, which could be rescued by the removal of cCPE 194-319. Incubation of zebrafish larvae with cCPE 194-319 removed Cldnb specifically from the epidermal cell membrane. Dye diffusion analysis with 4-kDa fluorescent dextran indicated that the permeability of the epidermal barrier increased due to cCPE 194-319 incubation. Electron microscopic investigation revealed reversible loss of TJ integrity by Cldnb removal. Collectively, these results suggest that cCPE 194-319 could be used as a Cldnb modulator to transiently open the epidermal barrier in zebrafish. In addition, zebrafish might be used as an in vivo system to investigate the capability of cCPE to enhance drug delivery across tissue barriers. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Nicotinic Acid Receptor Abnormalities in Human Skin Cancer: Implications for a Role in Epidermal Differentiation

PubMed Central

Bermudez, Yira; Benavente, Claudia A.; Meyer, Ralph G.; Coyle, W. Russell; Jacobson, Myron K.; Jacobson, Elaine L.

2011-01-01

Background Chronic UV skin exposure leads to epidermal differentiation defects in humans that can be largely restored by pharmacological doses of nicotinic acid. Nicotinic acid has been identified as a ligand for the human G-protein-coupled receptors GPR109A and GPR109B that signal through Gi-mediated inhibition of adenylyl cyclase. We have examined the expression, cellular distribution, and functionality of GPR109A/B in human skin and skin derived epidermal cells. Results Nicotinic acid increases epidermal differentiation in photodamaged human skin as judged by the terminal differentiation markers caspase 14 and filaggrin. Both GPR109A and GPR109B genes are transcribed in human skin and in epidermal keratinocytes, but expression in dermal fibroblasts is below limits of detection. Receptor transcripts are greatly over-expressed in squamous cell cancers. Receptor protein in normal skin is prominent from the basal through granular layers of the epidermis, with cellular localization more dispersive in the basal layer but predominantly localized at the plasma membrane in more differentiated epidermal layers. In normal human primary and immortalized keratinocytes, nicotinic acid receptors show plasma membrane localization and functional Gi-mediated signaling. In contrast, in a squamous cell carcinoma derived cell line, receptor protein shows a more diffuse cellular localization and the receptors are nearly non-functional. Conclusions The results of these studies justify future genetic and pharmacological intervention studies to define possible specific role(s) of nicotinic acid receptors in human skin homeostasis. PMID:21655214

Relationship between the ability of sunscreens containing 2-ethylhexyl-4'-methoxycinnamate to protect against UVR-induced inflammation, depletion of epidermal Langerhans (Ia+) cells and suppression of alloactivating capacity of murine skin in vivo.

PubMed

Walker, S L; Morris, J; Chu, A C; Young, A R

1994-01-01

The UVB sunscreen 2-ethylhexyl-4'-methoxycinnamate was evaluated in hairless albino mouse skin for its ability to inhibit UVR-induced (i) oedema, (ii) epidermal Langerhans cell (Ia+) depletion and (iii) suppression of the alloactivating capacity of epidermal cells (mixed epidermal cell-lymphocyte reaction, MECLR). The sunscreen, prepared at 9% in ethanol or a cosmetic lotion, was applied prior to UVB/UVA irradiation. In some experiments there was a second application halfway through the irradiation. Single applications in both vehicles gave varying degrees of protection from oedema and Langerhans cell depletion but afforded no protection from suppression of MECLR. When the sunscreens were applied twice there was improved protection from oedema and Langerhans cell depletion and complete protection was afforded from suppression of MECLR. There was a clear linear relationship between Langerhans cell numbers and oedema with and without sunscreen application. The relationship between Langerhans cell numbers and MECLR was more complex. These data confirm published discrepancies between protection from oedema (a model for human erythema) and endpoints with immunological significance, but show that 2-ethylhexyl-4'-methoxycinnamate can afford complete immunoprotection, although protection is dependent on the application rate and vehicle.

Highly stretchable and ultrathin nanopaper composites for epidermal strain sensors.

PubMed

Sun, Jingyao; Zhao, Yanan; Yang, Zhaogang; Shen, Jingjing; Cabrera, Eusebio; Lertola, Matthew J; Yang, Willie; Zhang, Dan; Benatar, Avi; Castro, Jose M; Wu, Daming; Lee, L James

2018-08-31

Multifunctional electronics are attracting great interest with the increasing demand and fast development of wearable electronic devices. Here, we describe an epidermal strain sensor based on an all-carbon conductive network made from multi-walled carbon nanotubes (MWCNTs) impregnated with poly(dimethyl siloxane) (PDMS) matrix through a vacuum filtration process. An ultrasonication treatment was performed to complete the penetration of PDMS resin in seconds. The entangled and overlapped MWCNT network largely enhances the electrical conductivity (1430 S m -1 ), uniformity (remaining stable on different layers), reliable sensing range (up to 80% strain), and cyclic stability of the strain sensor. The homogeneous dispersion of MWCNTs within the PDMS matrix leads to a strong interaction between the two phases and greatly improves the mechanical stability (ca. 160% strain at fracture). The flexible, reversible and ultrathin (<100 μm) film can be directly attached on human skin as epidermal strain sensors for high accuracy and real-time human motion detection.

Delineation of Matriptase Protein Expression by Enzymatic Gene Trapping Suggests Diverging Roles in Barrier Function, Hair Formation, and Squamous Cell Carcinogenesis

PubMed Central

List, Karin; Szabo, Roman; Molinolo, Alfredo; Nielsen, Boye Schnack; Bugge, Thomas H.

2006-01-01

The membrane serine protease matriptase is required for epidermal barrier function, hair formation, and thymocyte development in mice, and dysregulated matriptase expression causes epidermal squamous cell carcinoma. To elucidate the specific functions of matriptase in normal and aberrant epidermal differentiation, we used enzymatic gene trapping combined with immunohistochemical, ultrastructural, and barrier function assays to delineate the spatio-temporal expression and function of matriptase in mouse keratinized tissue development, homeostasis, and malignant transformation. In the interfollicular epidermis, matriptase expression was restricted to postmitotic transitional layer keratinocytes undergoing terminal differentiation. Matriptase was also expressed in keratinizing oral epithelium, where it was required for oral barrier function, and in thymic epithelium. In all three tissues, matriptase colocalized with profilaggrin. In staged embryos, the onset of epidermal matriptase expression coincided with that of profilaggrin expression and acquisition of the epidermal barrier. In marked contrast to stratifying keritinized epithelium, matripase expression commenced already in undifferentiated and rapidly proliferating profilaggrin-negative matrix cells and displayed hair growth cycle-dependent expression. Exposure of the epidermis to carcinogens led to the gradual appearance of matriptase in a keratin-5-positive proliferative cell compartment during malignant progression. Combined with previous studies, these data suggest that matriptase has diverging functions in the genesis of stratified keratinized epithelium, hair follicles, and squamous cell carcinoma. PMID:16651618

Delineation of matriptase protein expression by enzymatic gene trapping suggests diverging roles in barrier function, hair formation, and squamous cell carcinogenesis.

PubMed

List, Karin; Szabo, Roman; Molinolo, Alfredo; Nielsen, Boye Schnack; Bugge, Thomas H

2006-05-01

The membrane serine protease matriptase is required for epidermal barrier function, hair formation, and thymocyte development in mice, and dysregulated matriptase expression causes epidermal squamous cell carcinoma. To elucidate the specific functions of matriptase in normal and aberrant epidermal differentiation, we used enzymatic gene trapping combined with immunohistochemical, ultrastructural, and barrier function assays to delineate the spatio-temporal expression and function of matriptase in mouse keratinized tissue development, homeostasis, and malignant transformation. In the interfollicular epidermis, matriptase expression was restricted to postmitotic transitional layer keratinocytes undergoing terminal differentiation. Matriptase was also expressed in keratinizing oral epithelium, where it was required for oral barrier function, and in thymic epithelium. In all three tissues, matriptase colocalized with profilaggrin. In staged embryos, the onset of epidermal matriptase expression coincided with that of profilaggrin expression and acquisition of the epidermal barrier. In marked contrast to stratifying keritinized epithelium, matripase expression commenced already in undifferentiated and rapidly proliferating profilaggrin-negative matrix cells and displayed hair growth cycle-dependent expression. Exposure of the epidermis to carcinogens led to the gradual appearance of matriptase in a keratin-5-positive proliferative cell compartment during malignant progression. Combined with previous studies, these data suggest that matriptase has diverging functions in the genesis of stratified keratinized epithelium, hair follicles, and squamous cell carcinoma.

The anisotropy1 D604N Mutation in the Arabidopsis Cellulose Synthase1 Catalytic Domain Reduces Cell Wall Crystallinity and the Velocity of Cellulose Synthase Complexes1[W][OA

PubMed Central

Fujita, Miki; Himmelspach, Regina; Ward, Juliet; Whittington, Angela; Hasenbein, Nortrud; Liu, Christine; Truong, Thy T.; Galway, Moira E.; Mansfield, Shawn D.; Hocart, Charles H.; Wasteneys, Geoffrey O.

2013-01-01

Multiple cellulose synthase (CesA) subunits assemble into plasma membrane complexes responsible for cellulose production. In the Arabidopsis (Arabidopsis thaliana) model system, we identified a novel D604N missense mutation, designated anisotropy1 (any1), in the essential primary cell wall CesA1. Most previously identified CesA1 mutants show severe constitutive or conditional phenotypes such as embryo lethality or arrest of cellulose production but any1 plants are viable and produce seeds, thus permitting the study of CesA1 function. The dwarf mutants have reduced anisotropic growth of roots, aerial organs, and trichomes. Interestingly, cellulose microfibrils were disordered only in the epidermal cells of the any1 inflorescence stem, whereas they were transverse to the growth axis in other tissues of the stem and in all elongated cell types of roots and dark-grown hypocotyls. Overall cellulose content was not altered but both cell wall crystallinity and the velocity of cellulose synthase complexes were reduced in any1. We crossed any1 with the temperature-sensitive radial swelling1-1 (rsw1-1) CesA1 mutant and observed partial complementation of the any1 phenotype in the transheterozygotes at rsw1-1’s permissive temperature (21°C) and full complementation by any1 of the conditional rsw1-1 root swelling phenotype at the restrictive temperature (29°C). In rsw1-1 homozygotes at restrictive temperature, a striking dissociation of cellulose synthase complexes from the plasma membrane was accompanied by greatly diminished motility of intracellular cellulose synthase-containing compartments. Neither phenomenon was observed in the any1 rsw1-1 transheterozygotes, suggesting that the proteins encoded by the any1 allele replace those encoded by rsw1-1 at restrictive temperature. PMID:23532584

The anisotropy1 D604N mutation in the Arabidopsis cellulose synthase1 catalytic domain reduces cell wall crystallinity and the velocity of cellulose synthase complexes.

PubMed

Fujita, Miki; Himmelspach, Regina; Ward, Juliet; Whittington, Angela; Hasenbein, Nortrud; Liu, Christine; Truong, Thy T; Galway, Moira E; Mansfield, Shawn D; Hocart, Charles H; Wasteneys, Geoffrey O

2013-05-01

Multiple cellulose synthase (CesA) subunits assemble into plasma membrane complexes responsible for cellulose production. In the Arabidopsis (Arabidopsis thaliana) model system, we identified a novel D604N missense mutation, designated anisotropy1 (any1), in the essential primary cell wall CesA1. Most previously identified CesA1 mutants show severe constitutive or conditional phenotypes such as embryo lethality or arrest of cellulose production but any1 plants are viable and produce seeds, thus permitting the study of CesA1 function. The dwarf mutants have reduced anisotropic growth of roots, aerial organs, and trichomes. Interestingly, cellulose microfibrils were disordered only in the epidermal cells of the any1 inflorescence stem, whereas they were transverse to the growth axis in other tissues of the stem and in all elongated cell types of roots and dark-grown hypocotyls. Overall cellulose content was not altered but both cell wall crystallinity and the velocity of cellulose synthase complexes were reduced in any1. We crossed any1 with the temperature-sensitive radial swelling1-1 (rsw1-1) CesA1 mutant and observed partial complementation of the any1 phenotype in the transheterozygotes at rsw1-1's permissive temperature (21°C) and full complementation by any1 of the conditional rsw1-1 root swelling phenotype at the restrictive temperature (29°C). In rsw1-1 homozygotes at restrictive temperature, a striking dissociation of cellulose synthase complexes from the plasma membrane was accompanied by greatly diminished motility of intracellular cellulose synthase-containing compartments. Neither phenomenon was observed in the any1 rsw1-1 transheterozygotes, suggesting that the proteins encoded by the any1 allele replace those encoded by rsw1-1 at restrictive temperature.

Examination of tetrachlorosalicylanilide (TCSA) photoallergy using in vitro photohapten-modified Langerhans cell-enriched epidermal cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gerberick, G.F.; Ryan, C.A.; Von Bargen, E.C.

Lymphocytes from BALB/c mice photosensitized in vivo to tetrachlorosalicylanilide (TCSA) were investigated to determine whether they could be stimulated to proliferate when cultured with Langerhans cell-enriched cultured epidermal cells (LC-EC) photohapten-modified in vitro with TCSA + UVA radiation. Cultured LC-EC were photohapten-modified in vitro by irradiation in TCSA-containing medium using a 1000-watt solar simulator equipped with filters to deliver primarily UVA radiation (320-400 nm). Lymphocytes from TCSA-photosensitized mice were incubated with LC-EC that had been treated in vitro with 0.1 mM TCSA and 2 J/cm2 UVA radiation (TCSA + UVA). Responder lymphocytes demonstrated a significant increase in their blastogenesis responsemore » compared to lymphocytes that were incubated with LC-EC irradiated with UVA prior to treatment with TCSA (UVA/TCSA) or with LC-EC that had received no treatment. Lymphocytes from naive mice or mice photosensitized with musk ambrette (MA) demonstrated a significantly lower response to LC-EC modified with TCSA + UVA, indicating the specificity of the response. Maximum blastogenesis response was achieved when LC-EC were treated with 0.1 mM TCSA and a UVA radiation dose of at least 0.5 J/cm2. Epidermal cells depleted of LC by treatment with anti-Ia antibody plus complement or by an adherence procedure were unable to stimulate this blastogenesis response. Epidermal cells treated in vitro with TCSA + UVA demonstrated enhanced fluorescence compared to control cells. The fluorescence observed was not restricted to any specific epidermal cell type; however, fluorescence microscopy studies revealed that dendritic Ia-positive cells, presumably LC, were also TCSA fluorescent.« less

Pointillist structural color in Pollia fruit

PubMed Central

Vignolini, Silvia; Rudall, Paula J.; Rowland, Alice V.; Reed, Alison; Moyroud, Edwige; Faden, Robert B.; Baumberg, Jeremy J.; Glover, Beverley J.; Steiner, Ullrich

2012-01-01

Biological communication by means of structural color has existed for at least 500 million years. Structural color is commonly observed in the animal kingdom, but has been little studied in plants. We present a striking example of multilayer-based strong iridescent coloration in plants, in the fruit of Pollia condensata. The color is caused by Bragg reflection of helicoidally stacked cellulose microfibrils that form multilayers in the cell walls of the epicarp. We demonstrate that animals and plants have convergently evolved multilayer-based photonic structures to generate colors using entirely distinct materials. The bright blue coloration of this fruit is more intense than that of any previously described biological material. Uniquely in nature, the reflected color differs from cell to cell, as the layer thicknesses in the multilayer stack vary, giving the fruit a striking pixelated or pointillist appearance. Because the multilayers form with both helicoidicities, optical characterization reveals that the reflected light from every epidermal cell is polarized circularly either to the left or to the right, a feature that has never previously been observed in a single tissue. PMID:23019355

Temporal and spatial characteristics of male cone development in Metasequoia glyptostroboides Hu et Cheng

PubMed Central

Jin, Biao; Tang, Liang; Lu, Yan; Wang, Di; Zhang, Min; Ma, Jiuxia

2012-01-01

Metasequoia glyptostroboides, a famous relic species of conifer that survived in China, has been successfully planted in large numbers across the world. However, limited information on male cone development in the species is available. In this study, we observed the morphological and anatomical changes that occur during male cone development in M. glyptostroboides using semi-thin sections and scanning electron microscopy. The male cones were borne oppositely on one-year-old twigs that were mainly located around the outer and sunlit parts of crown. Male cones were initiated from early September and shed pollen in the following February. Each cone consisted of spirally arranged microsporophylls subtended by decussate sterile scales, and each microsporophyll commonly consisted of three microsporangia and a phylloclade. The microsporangial wall was composed of an epidermis, endothecium, and tapetum. In mid-February, the endothecium and tapetum layers disintegrated, and in the epidermal layer the cell walls were thickened with inner protrusions. Subsequently, dehiscence of the microsporangia occurred through rupturing of the microsporangial wall along the dehiscence line. These results suggest that the structure, morphology, architecture and arrangement of male cones of M. glyptostroboides are mainly associated with the production, protection and dispersal of pollen for optimization of wind pollination. PMID:23221679

Temporal and spatial characteristics of male cone development in Metasequoia glyptostroboides Hu et Cheng.

PubMed

Jin, Biao; Tang, Liang; Lu, Yan; Wang, Di; Zhang, Min; Ma, Jiuxia

2012-12-01

Metasequoia glyptostroboides, a famous relic species of conifer that survived in China, has been successfully planted in large numbers across the world. However, limited information on male cone development in the species is available. In this study, we observed the morphological and anatomical changes that occur during male cone development in M. glyptostroboides using semi-thin sections and scanning electron microscopy. The male cones were borne oppositely on one-year-old twigs that were mainly located around the outer and sunlit parts of crown. Male cones were initiated from early September and shed pollen in the following February. Each cone consisted of spirally arranged microsporophylls subtended by decussate sterile scales, and each microsporophyll commonly consisted of three microsporangia and a phylloclade. The microsporangial wall was composed of an epidermis, endothecium, and tapetum. In mid-February, the endothecium and tapetum layers disintegrated, and in the epidermal layer the cell walls were thickened with inner protrusions. Subsequently, dehiscence of the microsporangia occurred through rupturing of the microsporangial wall along the dehiscence line. These results suggest that the structure, morphology, architecture and arrangement of male cones of M. glyptostroboides are mainly associated with the production, protection and dispersal of pollen for optimization of wind pollination.

Immunohistochemical demonstration of epidermal growth factor in human gastric cancer xenografts of nude mice.

PubMed

Yoshiyuki, T; Shimizu, Y; Onda, M; Tokunaga, A; Kiyama, T; Nishi, K; Mizutani, T; Matsukura, N; Tanaka, N; Akimoto, M

1990-02-15

Thirty-two surgical specimens and three cell lines of human gastric cancers were used for subcutaneous transplantation into nude mice, resulting in the establishment of eight (25%) xenografts from the surgical specimens and two (67%) from the cell lines. The localization of epidermal growth factor (EGF) in the surgical specimens and cell lines of the gastric cancers and their xenografts in nude mice was then investigated immunohistochemically. Epidermal growth factor was stained in the cytoplasm of the cancer cells, being detected in 16 (50%) of the 32 surgical specimens and in all of the cell lines. Seven (44%) of the sixteen EGF-positive surgical specimens and one (6%) of the 16 EGF-negative ones were tumorigenic in nude mice. All of the xenografts in nude mice were positive for EGF. The tumorigenicity of human gastric cancer xenografts in nude mice may, therefore, be correlated with the presence of EGF in cancer cells.

Thrombomodulin exerts cytoprotective effect on low-dose UVB-irradiated HaCaT cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iwata, Masahiro; Laboratory of Vascular Medicine, Department of Cardiovascular and Respiratory Disorders Advanced Therapeutics, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima 890-8520; Kawahara, Ko-ichi

Thrombomodulin (TM) is an endothelial cell surface anticoagulant glycoprotein that performs antimetastatic, angiogenic, adhesive, and anti-inflammatory functions in various tissues. It is also expressed in epidermal keratinocytes. We found that a physiological dose (10 mJ/cm{sup 2}) of mid-wavelength ultraviolet irradiation (UVB) significantly induced TM expression via the p38mitogen-activated protein kinase (MAPK)/cyclic AMP response element (CRE) signaling pathway in the epidermal keratinocyte cell line HaCaT; this shows that TM regulates the survival of HaCaT cells. SB203580, a p38MAPK inhibitor, significantly decreased TM expression and the viability of cells exposed to UVB. Furthermore, overexpression of TM markedly increased cell viability, and itmore » was abrogated by TM small interfering RNA (siRNA), suggesting that TM may play an important role in exerting cytoprotective effect on epidermal keratinocytes against low-dose UVB.« less

The xipotl Mutant of Arabidopsis Reveals a Critical Role for Phospholipid Metabolism in Root System Development and Epidermal Cell Integrity

PubMed Central

Cruz-Ramírez, Alfredo; López-Bucio, José; Ramírez-Pimentel, Gabriel; Zurita-Silva, Andrés; Sánchez-Calderon, Lenin; Ramírez-Chávez, Enrique; González-Ortega, Emmanuel; Herrera-Estrella, Luis

2004-01-01

Phosphocholine (PCho) is an essential metabolite for plant development because it is the precursor for the biosynthesis of phosphatidylcholine, which is the major lipid component in plant cell membranes. The main step in PCho biosynthesis in Arabidopsis thaliana is the triple, sequential N-methylation of phosphoethanolamine, catalyzed by S-adenosyl-l-methionine:phosphoethanolamine N-methyltransferase (PEAMT). In screenings performed to isolate Arabidopsis mutants with altered root system architecture, a T-DNA mutagenized line showing remarkable alterations in root development was isolated. At the seedling stage, the mutant phenotype is characterized by a short primary root, a high number of lateral roots, and short epidermal cells with aberrant morphology. Genetic and biochemical characterization of this mutant showed that the T-DNA was inserted at the At3g18000 locus (XIPOTL1), which encodes PEAMT (XIPOTL1). Further analyses revealed that inhibition of PCho biosynthesis in xpl1 mutants not only alters several root developmental traits but also induces cell death in root epidermal cells. Epidermal cell death could be reversed by phosphatidic acid treatment. Taken together, our results suggest that molecules produced downstream of the PCho biosynthesis pathway play key roles in root development and act as signals for cell integrity. PMID:15295103

Stomatal lock-open, a consequence of epidermal cell death, follows transient suppression of stomatal opening in barley attacked by Blumeria graminis.

PubMed

Prats, Elena; Gay, Alan P; Mur, Luis A J; Thomas, Barry J; Carver, Timothy L W

2006-01-01

Blumeria graminis f.sp. hordei (Bgh) attack disrupted stomatal behaviour, and hence leaf water conductance (g(l)), in barley genotypes Pallas and Risø-S (susceptible), P01 (with Mla1 conditioning a hypersensitive response; HR), and P22 and Risø-R (with mlo5 conditioning papilla-based penetration resistance). Inoculation caused some stomatal closure well before the fungus attempted infection. Coinciding with epidermal cell penetration, stomatal opening in light was also impeded, although stomata of susceptible and mlo5 lines remained largely able to close in darkness. Following infection, in susceptible lines stomata closed in darkness but opening in light was persistently impeded. In Risø-R, stomata recovered nearly complete function by approximately 30 h after inoculation, i.e. after penetration resistance was accomplished. In P01, stomata became locked open and unable to close in darkness shortly after epidermal cells died due to HR. In the P22 background, mlo5 penetration resistance was often followed by consequential death of attacked cells, and here too stomata became locked open, but not until approximately 24 h after pathogen attack had ceased. The influence of epidermal cell death was localized, and only affected stomata within one or two cells distance. These stomata were unable to close not only in darkness but also after application of abscisic acid and in wilted leaves suffering drought. Thus, resistance to Bgh based on HR or associated with cell death may have previously unsuspected negative consequences for the physiological health of apparently 'disease-free' plants. The results are discussed in relation to the control of stomatal aperture in barley by epidermal cells.

Mast Cells Regulate Epidermal Barrier Function and the Development of Allergic Skin Inflammation.

PubMed

Sehra, Sarita; Serezani, Ana P M; Ocaña, Jesus A; Travers, Jeffrey B; Kaplan, Mark H

2016-07-01

Atopic dermatitis is a chronic inflammatory skin disease characterized by infiltration of eosinophils, T helper cells, and mast cells. The role of mast cells in atopic dermatitis is not completely understood. To define the effects of mast cells on skin biology, we observed that mast cells regulate the homeostatic expression of epidermal differentiation complex and other skin genes. Decreased epidermal differentiation complex gene expression in mice that genetically lack mast cells (Kit(W-sh/W-sh) mice) is associated with increased uptake of protein antigens painted on the skin by dendritic cells (DCs) compared with similarly treated wild-type mice, suggesting a protective role for mast cells in exposure to nominal environmental allergens. To test this further, we crossed Kit(W-sh/W-sh) mice with signal transducer and activator of transcription 6 (i.e., Stat6) VT transgenic mice that develop spontaneous atopic dermatitis-like disease that is dependent on T helper cell 2 cytokines and is associated with high serum concentrations of IgE. We observed that Stat6VT × Kit(W-sh/W-sh) mice developed more frequent and more severe allergic skin inflammation than Stat6VT transgenic mice that had mast cells. Together, these studies suggest that mast cells regulate epidermal barrier function and have a potential protective role in the development of atopic dermatitis-like disease. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Interactions Between Epidermal Keratinocytes, Dendritic Epidermal T-Cells, and Hair Follicle Stem Cells.

PubMed

Badarinath, Krithika; Dutta, Abhik; Hegde, Akshay; Pincha, Neha; Gund, Rupali; Jamora, Colin

2018-06-13

The interplay of immune cells and stem cells in maintaining skin homeostasis and repair is an exciting new frontier in cutaneous biology. With the growing appreciation of the importance of this new crosstalk comes the requirement of methods to interrogate the molecular underpinnings of these leukocyte-stem cell interactions. Here we describe how a combination of FACS, cellular coculture assays, and conditioned media treatments can be utilized to advance our understanding of this emerging area of intercellular communication between immune cells and stem cells.

Bioengineering a Human Plasma-Based Epidermal Substitute With Efficient Grafting Capacity and High Content in Clonogenic Cells

PubMed Central

Alexaline, Maia M.; Trouillas, Marina; Nivet, Muriel; Bourreau, Emilie; Leclerc, Thomas; Duhamel, Patrick; Martin, Michele T.; Doucet, Christelle; Fortunel, Nicolas O.

2015-01-01

Cultured epithelial autografts (CEAs) produced from a small, healthy skin biopsy represent a lifesaving surgical technique in cases of full-thickness skin burn covering >50% of total body surface area. CEAs also present numerous drawbacks, among them the use of animal proteins and cells, the high fragility of keratinocyte sheets, and the immaturity of the dermal-epidermal junction, leading to heavy cosmetic and functional sequelae. To overcome these weaknesses, we developed a human plasma-based epidermal substitute (hPBES) for epidermal coverage in cases of massive burn, as an alternative to traditional CEA, and set up critical quality controls for preclinical and clinical studies. In this study, phenotypical analyses in conjunction with functional assays (clonal analysis, long-term culture, or in vivo graft) showed that our new substitute fulfills the biological requirements for epidermal regeneration. hPBES keratinocytes showed high potential for cell proliferation and subsequent differentiation similar to healthy skin compared with a well-known reference material, as ascertained by a combination of quality controls. This work highlights the importance of integrating relevant multiparameter quality controls into the bioengineering of new skin substitutes before they reach clinical development. Significance This work involves the development of a new bioengineered epidermal substitute with pertinent functional quality controls. The novelty of this work is based on this quality approach. PMID:25848122

Bioengineering a human plasma-based epidermal substitute with efficient grafting capacity and high content in clonogenic cells.

PubMed

Alexaline, Maia M; Trouillas, Marina; Nivet, Muriel; Bourreau, Emilie; Leclerc, Thomas; Duhamel, Patrick; Martin, Michele T; Doucet, Christelle; Fortunel, Nicolas O; Lataillade, Jean-Jacques

2015-06-01

Cultured epithelial autografts (CEAs) produced from a small, healthy skin biopsy represent a lifesaving surgical technique in cases of full-thickness skin burn covering >50% of total body surface area. CEAs also present numerous drawbacks, among them the use of animal proteins and cells, the high fragility of keratinocyte sheets, and the immaturity of the dermal-epidermal junction, leading to heavy cosmetic and functional sequelae. To overcome these weaknesses, we developed a human plasma-based epidermal substitute (hPBES) for epidermal coverage in cases of massive burn, as an alternative to traditional CEA, and set up critical quality controls for preclinical and clinical studies. In this study, phenotypical analyses in conjunction with functional assays (clonal analysis, long-term culture, or in vivo graft) showed that our new substitute fulfills the biological requirements for epidermal regeneration. hPBES keratinocytes showed high potential for cell proliferation and subsequent differentiation similar to healthy skin compared with a well-known reference material, as ascertained by a combination of quality controls. This work highlights the importance of integrating relevant multiparameter quality controls into the bioengineering of new skin substitutes before they reach clinical development. This work involves the development of a new bioengineered epidermal substitute with pertinent functional quality controls. The novelty of this work is based on this quality approach. ©AlphaMed Press.

Signalling in the epidermis: the E2F cell cycle regulatory pathway in epidermal morphogenesis, regeneration and transformation.

PubMed

Ivanova, Iordanka A; D'Souza, Sudhir J A; Dagnino, Lina

2005-01-01

The epidermis is the outermost layer in the skin, and it is the first line of defence against the environment. The epidermis also provides a barrier against loss of fluids and electrolytes, which is crucial for life. Essential in the maintenance of this tissue is its ability to continually self-renew and regenerate after injury. These two characteristics are critically dependent on the ability of the principal epidermal cell type, the keratinocyte, to proliferate and to respond to differentiation cues. Indeed, the epidermis is a multilayered tissue composed of keratinocyte stem cells and their differentiated progeny. Central for the control of cell proliferation is the E2F transcription factor regulatory network. This signaling network also includes cyclins, cdk, cdk inhibitors and the retinoblastoma (pRb) family of proteins. The biological importance of the E2F/pRb pathway is emphasized by the fact that a majority of human tumours exhibit alterations that disrupt the ability of pRb proteins to inhibit E2F, leading to permanent activation of the latter. Further, E2F is essential for normal epidermal regeneration after injury. Other member of the E2F signaling pathway are also involved in epidermal development and pathophysiology. Thus, whereas the pRb family of proteins is essential for epidermal morphogenesis, abnormal regulation of cyclins and E2F proteins results in tumorgenesis in this tissue. In this review, we discuss the role of each member of this important growth regulatory network in epidermal formation, homeostasis and carcinogenesis.

Signalling In The Epidermis: The E2f Cell Cycle Regulatory Pathway In Epidermal Morphogenesis, Regeneration And Transformation

PubMed Central

2005-01-01

The epidermis is the outermost layer in the skin, and it is the first line of defence against the environment. The epidermis also provides a barrier against loss of fluids and electrolytes, which is crucial for life. Essential in the maintenance of this tissue is its ability to continually self-renew and regenerate after injury. These two characteristics are critically dependent on the ability of the principal epidermal cell type, the keratinocyte, to proliferate and to respond to differentiation cues. Indeed, the epidermis is a multilayered tissue composed of keratinocyte stem cells and their differentiated progeny. Central for the control of cell proliferation is the E2F transcription factor regulatory network. This signaling network also includes cyclins, cdk, cdk inhibitors and the retinoblastoma (pRb) family of proteins. The biological importance of the E2F/pRb pathway is emphasized by the fact that a majority of human tumours exhibit alterations that disrupt the ability of pRb proteins to inhibit E2F, leading to permanent activation of the latter. Further, E2F is essential for normal epidermal regeneration after injury. Other member of the E2F signaling pathway are also involved in epidermal development and pathophysiology. Thus, whereas the pRb family of proteins is essential for epidermal morphogenesis, abnormal regulation of cyclins and E2F proteins results in tumorgenesis in this tissue. In this review, we discuss the role of each member of this important growth regulatory network in epidermal formation, homeostasis and carcinogenesis. PMID:15951853

Mast cells are dispensable in a genetic mouse model of chronic dermatitis.

PubMed

Sulcova, Jitka; Meyer, Michael; Guiducci, Eva; Feyerabend, Thorsten B; Rodewald, Hans-Reimer; Werner, Sabine

2015-06-01

Chronic inflammatory skin diseases, such as atopic dermatitis, affect a large percentage of the population, but the role of different immune cells in the pathogenesis of these disorders is largely unknown. Recently, we found that mice lacking fibroblast growth factor receptor 1 (Fgfr1) and Fgfr2 (K5-R1/R2 mice) in the epidermis have a severe impairment in the epidermal barrier, which leads to the development of a chronic inflammatory skin disease that shares many features with human atopic dermatitis. Using Fgfr1-/Fgfr2-deficient mice, we analyzed the consequences of the loss of mast cells. Mast cells accumulated and degranulated in the skin of young Fgfr1-/Fgfr2-deficient mice, most likely as a consequence of increased expression of the mast cell chemokine Ccl2. The increase in mast cells occurred before the development of histological abnormalities, indicating a functional role of these cells in the inflammatory skin phenotype. To test this hypothesis, we mated the Fgfr1-/Fgfr2-deficient mice with mast cell-deficient CreMaster mice. Surprisingly, loss of mast cells did not or only mildly affect keratinocyte proliferation, epidermal thickness, epidermal barrier function, accumulation and activation of different immune cells, or expression of different proinflammatory cytokines in the skin. These results reveal that mast cells are dispensable for the development of chronic inflammation in response to a defect in the epidermal barrier. Copyright © 2015 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

Virus-Induced Gene Silencing of the Eggplant Chalcone Synthase Gene during Fruit Ripening Modifies Epidermal Cells and Gravitropism.

PubMed

Wang, Cuicui; Fu, Daqi

2018-03-21

Eggplant ( Solanum melongena L.) fruits accumulate flavonoids in their cuticle and epidermal cells during ripening. Although many mutants available in model plant species, such as Arabidopsis thaliana and Medicago truncatula, are enabling the intricacies of flavonoid-related physiology to be deduced, the mechanisms whereby flavonoids influence eggplant fruit physiology are unknown. Virus-induced gene silencing (VIGS) is a reliable tool for the study of flavonoid function in fruit, and in this study, we successfully applied this technique to downregulate S. melongena chalcone synthase gene ( SmCHS) expression during eggplant fruit ripening. In addition to the expected change in fruit color attributable to a lack of anthocyanins, several other modifications, including differences in epidermal cell size and shape, were observed in the different sectors. We also found that silencing of CHS gene expression was associated with a negative gravitropic response in eggplant fruits. These observations indicate that epidermal cell expansion during ripening is dependent upon CHS expression and that there may be a relationship between CHS expression and gravitropism during eggplant fruit ripening.

Transient elevation of cytoplasmic calcium ion concentration at a single cell level precedes morphological changes of epidermal keratinocytes during cornification.

PubMed

Murata, Teruasa; Honda, Tetsuya; Egawa, Gyohei; Yamamoto, Yasuo; Ichijo, Ryo; Toyoshima, Fumiko; Dainichi, Teruki; Kabashima, Kenji

2018-04-26

Epidermal keratinocytes achieve sequential differentiation from basal to granular layers, and undergo a specific programmed cell death, cornification, to form an indispensable barrier of the body. Although elevation of the cytoplasmic calcium ion concentration ([Ca 2+ ] i ) is one of the factors predicted to regulate cornification, the dynamics of [Ca 2+ ] i in epidermal keratinocytes is largely unknown. Here using intravital imaging, we captured the dynamics of [Ca 2+ ] i in mouse skin. [Ca 2+ ] i was elevated in basal cells on the second time scale in three spatiotemporally distinct patterns. The transient elevation of [Ca 2+ ] i also occurred at the most apical granular layer at a single cell level, and lasted for approximately 40 min. The transient elevation of [Ca 2+ ] i at the granular layer was followed by cornification, which was completed within 10 min. This study demonstrates the tightly regulated elevation of [Ca 2+ ] i preceding the cornification of epidermal keratinocytes, providing possible clues to the mechanisms of cornification.

A new Gsdma3 mutation affecting anagen phase of first hair cycle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanaka, Shigekazu; Department of Genetics, School of Life Science, Graduate University for Advanced Studies, 1111 Yata, Mishima, Shizuoka 411-8540; Tamura, Masaru

2007-08-10

Recombination-induced mutation 3 (Rim3) is a spontaneous mouse mutation that exhibits dominant phenotype of hyperkeratosis and hair loss. Fine linkage analysis of Rim3 and sequencing revealed a novel single point mutation, G1124A leading to Ala348Thr, in Gsdma3 in chromosome 11. Transgenesis with BAC DNA harboring the Rim3-type Gsdma3 recaptured the Rim3 phenotype, providing direct evidence that Gsdma3 is the causative gene of Rim3. We examined the spatial expression of Gsdma3 and characterized the Rim3 phenotype in detail. Gsdma3 is expressed in differentiated epidermal cells in the skin, but not in the proliferating epidermal cells. Histological analysis of Rim3 mutant showedmore » hyperplasia of the epidermal cells in the upper hair follicles and abnormal anagen phase at the first hair cycle. Furthermore, immunohistochemical analysis revealed hyperproliferation and misdifferentiation of the upper follicular epidermis in Rim3 mutant. These results suggest that Gsdma3 is involved in the proliferation and differentiation of epidermal stem cells.« less

The THO Complex Non-Cell-Autonomously Represses Female Germline Specification through the TAS3-ARF3 Module.

PubMed

Su, Zhenxia; Zhao, Lihua; Zhao, Yuanyuan; Li, Shaofang; Won, SoYoun; Cai, Hanyang; Wang, Lulu; Li, Zhenfang; Chen, Piaojuan; Qin, Yuan; Chen, Xuemei

2017-06-05

In most sexually reproducing plants, a single somatic, sub-epidermal cell in an ovule is selected to differentiate into a megaspore mother cell, which is committed to giving rise to the female germline. However, it remains unclear how intercellular signaling among somatic cells results in only one cell in the sub-epidermal layer differentiating into the megaspore mother cell. Here we uncovered a role of the THO complex in restricting the megaspore mother cell fate to a single cell. Mutations in TEX1, HPR1, and THO6, components of the THO/TREX complex, led to the formation of multiple megaspore mother cells, which were able to initiate gametogenesis. We demonstrated that TEX1 repressed the megaspore mother cell fate by promoting the biogenesis of TAS3-derived trans-acting small interfering RNA (ta-siRNA), which represses ARF3 expression. The TEX1 protein was present in epidermal cells, but not in the germline, and, through TAS3-derived ta-siRNA, restricted ARF3 expression to the medio domain of ovule primordia. Expansion of ARF3 expression into lateral epidermal cells in a TAS3 ta-siRNA-insensitive mutant led to the formation of supernumerary megaspore mother cells, suggesting that TEX1- and TAS3-mediated restriction of ARF3 expression limits excessive megaspore mother cell formation non-cell-autonomously. Our findings reveal the role of a small-RNA pathway in the regulation of female germline specification in Arabidopsis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Exfoliation of the epidermal cells and defecation by amphibian larvae in response to coelomic fluid and lysenin from the earthworm Eisenia foetida.

PubMed

Kobayashi, Hideshi; Suzuki, Hirohumi; Ohta, Naoshi

2006-08-01

Coelomic fluid (CF) and lysenin from the earthworm Eisenia foetida induced heavy epidermal exfoliation in the larvae of Bufo japonicus formosus at developmental stages from hatching (stage 22) to operculum completion (stage 34). In experiments with Xenopus laevis, we observed that exfoliated cells were not stained by trypan blue. Thus, it appeared that these cells were still alive. It is likely, therefore, that both CF and lysenin might disrupt the adhesion between epidermal cells of larvae prior to stage 34. Since it is known that lysenin exerts its toxic effects through its specific binding to sphingomyelin (SM), SM might be involved in such adhesion. This hypothesis was supported by the observations that CF and lysenin which had been incubated with SM-liposomes lost their exfoliative activity. In larvae after stage 34, the mechanism of adhesion between epidermal cells seemed to change and the adhesion was no longer disrupted by CF and lysenin. In larvae at around stage 34, a collagen layer started to form beneath the basement membrane of the epidermis. Furthermore, larvae at around this stage started to eat solid food. The developing collagen layer and food intake might be related indirectly to the chemical change in epidermal adhesion. The induction of exfoliation by CF and lysenin was also observed in other amphibian species. In Bufo larvae, defecation was induced both by CF and by lysenin but this effect was independent of exfoliation.

Novel targeted approaches to treating biliary tract cancer: the dual epidermal growth factor receptor and ErbB-2 tyrosine kinase inhibitor NVP-AEE788 is more efficient than the epidermal growth factor receptor inhibitors gefitinib and erlotinib.

PubMed

Wiedmann, Marcus; Feisthammel, Jürgen; Blüthner, Thilo; Tannapfel, Andrea; Kamenz, Thomas; Kluge, Annett; Mössner, Joachim; Caca, Karel

2006-08-01

Aberrant activation of the epidermal growth factor receptor is frequently observed in neoplasia, notably in tumors of epithelial origin. Attempts to treat such tumors with epidermal growth factor receptor antagonists resulted in remarkable success in recent studies. Little is known, however, about the efficacy of this therapy in biliary tract cancer. Protein expression of epidermal growth factor receptor, ErbB-2, and vascular endothelial growth factor receptor-2 was assessed in seven human biliary tract cancer cell lines by immunoblotting. In addition, histological sections from 19 patients with extrahepatic cholangiocarcinoma were analyzed for epidermal growth factor receptor, ErbB-2 and vascular endothelial growth factor receptor-2 expression by immunohistochemistry. Moreover, we sequenced the cDNA products representing the entire epidermal growth factor receptor coding region of the seven cell lines, and searched for genomic epidermal growth factor receptor amplifications and polysomy by fluorescence in-situ hybridization. Cell growth inhibition by gefitinib erlotinib and NVP-AEE788 was studied in vitro by automated cell counting. In addition, the anti-tumoral effect of erlotinib and NVP-AEE788 was studied in a chimeric mouse model. The anti-tumoral drug mechanism in this model was assessed by MIB-1 antibody staining, terminal deoxynucleotidyl transfer-mediated dUTP nick end-labelling assay, von Willebrand factor staining, and immunoblotting for p-p42/44 (p-Erk1/2, p-MAPK) and p-AKT. Immunoblotting revealed expression of epidermal growth factor receptor, ErbB-2, and vascular endothelial growth factor receptor-2 in all biliary tract cancer cell lines. EGFR was detectable in six of 19 (32%) extrahepatic human cholangiocarcinoma tissue samples, ErbB-2 in 16 of 19 (84%), and vascular endothelial growth factor receptor-2 in nine of 19 (47%). Neither epidermal growth factor receptor mutations nor amplifications or polysomy were found in the seven biliary tract cancer cell lines. Gefitinib, erlotinib and NVP-AEE788 caused a significant growth inhibition in vitro; however, there was a significant difference in efficacy (NVP-AEE788>erlotinib>gefitinib). After 14 days of in-vivo treatment, using the chimeric mouse model, tumors had a significantly reduced volume and mass after NVP-AEE788, but not after erlotinib treatment, as compared with placebo. Reduction of proliferation (signalling via the mitogen-activated protein kinase pathway), induction of apoptosis and inhibition of angiogenesis were the main mechanisms of drug action. No significant reduction of anti-apoptotic AKT phosphorylation, however, occurred, which may be a possible counter mechanism of the tumor. Epidermal growth factor receptor, ErbB-2, and vascular endothelial growth factor receptor-2 expression was detectable in biliary tract cancer, and receptor inhibition exerts marked effects on tumor growth in vitro and in vivo, which was strongest for the dual EGFR/ErbB-2 inhibitor NVP-AEE788. Therefore, further clinical evaluation of this new drug for the treatment of biliary tract cancer is recommended.

Evolution of petal epidermal micromorphology in Leguminosae and its use as a marker of petal identity

PubMed Central

Ojeda, Isidro; Francisco-Ortega, Javier; Cronk, Quentin C. B.

2009-01-01

Background and Aims The legume flower is highly variable in symmetry and differentiation of petal types. Most papilionoid flowers are zygomorphic with three types of petals: one dorsal, two lateral and two ventral petals. Mimosoids have radial flowers with reduced petals while caesalpinioids display a range from strongly zygomorphic to nearly radial symmetry. The aims are to characterize the petal micromorphology relative to flower morphology and evolution within the family and assess its use as a marker of petal identity (whether dorsal, lateral or ventral) as determined by the expression of developmental genes. Methods Petals were analysed using the scanning electron microscope and light microscope. A total of 175 species were studied representing 26 tribes and 89 genera in all three subfamilies of the Leguminosae. Key Results The papilionoids have the highest degree of variation of epidermal types along the dorsiventral axis within the flower. In Loteae and genistoids, in particular, it is common for each petal type to have a different major epidermal micromorphology. Papillose conical cells are mainly found on dorsal and lateral petals. Tabular rugose cells are mainly found on lateral petals and tabular flat cells are found only in ventral petals. Caesalpinioids lack strong micromorphological variation along this axis and usually have only a single major epidermal type within a flower, although the type maybe either tabular rugose cells, papillose conical cells or papillose knobby rugose cells, depending on the species. Conclusions Strong micromorphological variation between different petals in the flower is exclusive to the subfamily Papilionoideae. Both major and minor epidermal types can be used as micromorphological markers of petal identity, at least in papilionoids, and they are important characters of flower evolution in the whole family. The molecular developmental pathway between specific epidermal micromorphology and the expression of petal identity genes has yet to be established. PMID:19789174

Ultra-weak photon emission as a non-invasive tool for monitoring of oxidative processes in the epidermal cells of human skin: comparative study on the dorsal and the palm side of the hand.

PubMed

Rastogi, Anshu; Pospísil, Pavel

2010-08-01

All living organisms emit spontaneous ultra-weak photon emission as a result of cellular metabolic processes. Exposure of living organisms to exogenous factors results in oxidative processes and enhancement in ultra-weak photon emission. Here, hydrogen peroxide (H(2)O(2)), as a strongly oxidizing molecule, was used to induce oxidative processes and enhance ultra-weak photon emission in human hand skin. The presented work intends to compare both spontaneous and peroxide-induced ultra-weak photon emission from the epidermal cells on the dorsal and the palm side of the hand. A highly sensitive photomultiplier tube and a charge-coupled device camera were used to detect ultra-weak photon emission from human hand skin. Spontaneous ultra-weak photon emission from the epidermal cells on the dorsal side of the hand was 4 counts/s. Topical application of 500 mM H(2)O(2) to the dorsal side of the hand caused enhancement in ultra-weak photon emission to 40 counts/s. Interestingly, both spontaneous and peroxide-induced ultra-weak photon emission from the epidermal cells on the palm side of the hand were observed to increase twice their values, i.e. 8 and 80 counts/s, respectively. Similarly, the two-dimensional image of ultra-weak photon emission observed after topical application of H(2)O(2) to human skin reveals that photon emission from the palm side exceeds the photon emission from the dorsal side of the hand. The results presented indicate that the ultra-weak photon emission originating from the epidermal cells on the dorsal and the palm side of the hand is related to the histological structure of the human hand skin. Ultra-weak photon emission is shown as a non-destructive technique for monitoring of oxidative processes in the epidermal cells of the human hand skin and as a diagnostic tool for skin diseases.

BAG-1 enhances cell-cell adhesion, reduces proliferation and induces chaperone-independent suppression of hepatocyte growth factor-induced epidermal keratinocyte migration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hinitt, C.A.M.; Wood, J.; Lee, S.S.

2010-08-01

Cell motility is important in maintaining tissue homeostasis, facilitating epithelial wound repair and in tumour formation and progression. The aim of this study was to determine whether BAG-1 isoforms regulate epidermal cell migration in in vitro models of wound healing. In the human epidermal cell line HaCaT, endogenous BAG-1 is primarily nuclear and increases with confluence. Both transient and stable p36-Bag-1 overexpression resulted in increased cellular cohesion. Stable transfection of either of the three human BAG-1 isoforms p36-Bag-1 (BAG-1S), p46-Bag-1 (BAG-1M) and p50-Bag-1 (BAG-1L) inhibited growth and wound closure in serum-containing medium. However, in response to hepatocyte growth factor (HGF)more » in serum-free medium, BAG-1S/M reduced communal motility and colony scattering, but BAG-1L did not. In the presence of HGF, p36-Bag-1 transfectants retained proliferative response to HGF with no change in ERK1/2 activation. However, the cells retained E-cadherin localisation at cell-cell junctions and exhibited pronounced cortical actin. Point mutations in the BAG domain showed that BAG-1 inhibition of motility is independent of its function as a chaperone regulator. These findings are the first to suggest that BAG-1 plays a role in regulating cell-cell adhesion and suggest an important function in epidermal cohesion.« less

Preparation of a Three-Dimensional Full Thickness Skin Equivalent.

PubMed

Reuter, Christian; Walles, Heike; Groeber, Florian

2017-01-01

In vitro test systems are a promising alternative to animal models. Due to the use of human cells in a three-dimensional arrangement that allows cell-cell or cell-matrix interactions these models may be more predictive for the human situation compared to animal models or two-dimensional cell culture systems. Especially for dermatological research, skin models such as epidermal or full-thickness skin equivalents (FTSE) are used for different applications. Although epidermal models provide highly standardized conditions for risk assessment, FTSE facilitate a cellular crosstalk between the dermal and epidermal layer and thus can be used as more complex models for the investigation of processes such as wound healing, skin development, or infectious diseases. In this chapter, we describe the generation and culture of an FTSE, based on a collagen type I matrix and provide troubleshooting tips for commonly encountered technical problems.

Estimating the Size of Onion Epidermal Cells from Diffraction Patterns

NASA Astrophysics Data System (ADS)

Groff, Jeffrey R.

2012-10-01

Bioscience and premedical profession students are a major demographic served by introductory physics courses at many colleges and universities. Exposing these students to biological applications of physical principles will help them to appreciate physics as a useful tool for their future professions. Here I describe an experiment suitable for introductory physics where principles of wave optics are applied to probe the size of onion epidermal cells. The epidermis tissue is composed of cells of relatively uniform size and shape (Fig. 1) so the tissue acts like a one-dimensional transmission diffraction grating. The diffraction patterns generated when a laser beam passes through the tissue (Fig. 2) are analyzed and an estimate of the average width of individual onion epidermal cells is calculated. The results are compared to direct measurements taken using a light microscope. The use of microscopes and plant-cell tissue slides creates opportunities for cross-discipline collaboration between physics and biology instructors.

Human papillomavirus E6/E7 oncogenes promote mouse ear regeneration by increasing the rate of wound re-epithelization and epidermal growth.

PubMed

Valencia, Concepción; Bonilla-Delgado, José; Oktaba, Katarzyna; Ocádiz-Delgado, Rodolfo; Gariglio, Patricio; Covarrubias, Luis

2008-12-01

Mammals have limited regeneration capacity. We report here that, in transgenic mice (Tg(bK6-E6/E7)), the expression of the E6/E7 oncogenes of human papilloma virus type 16 (HPV16) under the control of the bovine keratin 6 promoter markedly improves the mouse's capacity to repair portions of the ear after being wounded. Increased repair capacity correlates with an increased number of epidermal proliferating cells. In concordance with the expected effects of the E6 and E7 oncogenes, levels of p53 decreased and those of p16 in epidermal cells increased. In addition, we observed that wound re-epithelization proceeded faster in transgenic than in wild-type animals. After the initial re-epithelization, epidermal cell migration from the intact surrounding tissue appears to be a major contributor to the growing epidermis, especially in the repairing tissue of transgenic mice. We also found that there is a significantly higher number of putative epidermal stem cells in Tg(bK6-E6/E7) than in wild-type mice. Remarkably, hair follicles and cartilage regenerated within the repaired ear tissue, without evidence of tumor formation. We propose that the ability to regenerate ear portions is limited by the capacity of the epidermis to repair itself and grow.

Protein profiling of epidermal bladder cells from the halophyte Mesembryanthemum crystallinum.

PubMed

Barkla, Bronwyn J; Vera-Estrella, Rosario; Pantoja, Omar

2012-09-01

Plant epidermal trichomes are as varied in morphology as they are in function. In the halophyte Mesembryanthemum crystallinum, specialized trichomes called epidermal bladder cells (EBC) line the surface of leaves and stems, and increase dramatically in size and volume upon plant salt-treatment. These cells have been proposed to have roles in plant defense and UV protection, but primarily in sodium sequestration and as water reservoirs. To gain further understanding into the roles of EBC, a cell-type-specific proteomics approach was taken in which precision single-cell sampling of cell sap from individual EBC was combined with shotgun peptide sequencing (LC-MS/MS). Identified proteins showed diverse biological functions and cellular locations, with a high representation of proteins involved in H(+)-transport, carbohydrate metabolism, and photosynthesis. The proteome of EBC provides insight into the roles of these cells in ion and water homeostasis and raises the possibility that they are photosynthetically active and functioning in Crassulacean acid metabolism. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Elastase and matrix metalloproteinase activities are associated with pulmonary vascular disease in the nitrofen rat model of congenital diaphragmatic hernia.

PubMed

Wild, Benjamin; St-Pierre, Marie-Eve; Langlois, Stéphanie; Cowan, Kyle N

2017-05-01

Pulmonary vascular disease (PVD) is a leading cause of congenital diaphragmatic hernia (CDH) mortality. Progression of PVD involves extracellular matrix remodeling by elastases and matrix metalloproteinases (MMP), concomitant with proliferation of smooth muscle cells in a growth factor-enriched environment. Blockade of this pathway reversed primary pulmonary hypertension and improved survival. This study was designed to determine whether a similar pathway is induced in PVD secondary to CDH. Fetal rats exposed to nitrofen at gestational day 9 developed left-sided CDH and were compared at term to their non-CDH littermates by assessing histologic and biochemical features of PVD. Rats with CDH displayed right ventricle hypertrophy, increased pulmonary artery medial wall thickness and muscularization, and decreased lumen size. As revealed by in situ zymography and immunohistochemistry, this was associated with an induction of elastolytic and MMP activities as well as an elevation of epidermal growth factor and osteopontin levels in the diseased lung vasculature. CDH-associated PVD involves an induction of elastase and MMP activities and increased osteopontin deposition in an epidermal growth factor-rich environment. Inhibition of this pathway may thus represent a novel therapeutic approach for the treatment of CDH-associated PVD. Level I (Basic Science Study). Copyright © 2017 Elsevier Inc. All rights reserved.

The Arabidopsis thaliana REDUCED EPIDERMAL FLUORESCENCE1 gene encodes an aldehyde dehydrogenase involved in ferulic acid and sinapic acid biosynthesis.

PubMed

Nair, Ramesh B; Bastress, Kristen L; Ruegger, Max O; Denault, Jeff W; Chapple, Clint

2004-02-01

Recent research has significantly advanced our understanding of the phenylpropanoid pathway but has left in doubt the pathway by which sinapic acid is synthesized in plants. The reduced epidermal fluorescence1 (ref1) mutant of Arabidopsis thaliana accumulates only 10 to 30% of the sinapate esters found in wild-type plants. Positional cloning of the REF1 gene revealed that it encodes an aldehyde dehydrogenase, a member of a large class of NADP(+)-dependent enzymes that catalyze the oxidation of aldehydes to their corresponding carboxylic acids. Consistent with this finding, extracts of ref1 leaves exhibit low sinapaldehyde dehydrogenase activity. These data indicate that REF1 encodes a sinapaldehyde dehydrogenase required for sinapic acid and sinapate ester biosynthesis. When expressed in Escherichia coli, REF1 was found to exhibit both sinapaldehyde and coniferaldehyde dehydrogenase activity, and further phenotypic analysis of ref1 mutant plants showed that they contain less cell wall-esterified ferulic acid. These findings suggest that both ferulic acid and sinapic acid are derived, at least in part, through oxidation of coniferaldehyde and sinapaldehyde. This route is directly opposite to the traditional representation of phenylpropanoid metabolism in which hydroxycinnamic acids are instead precursors of their corresponding aldehydes.

Selective Ablation of Ctip2/Bcl11b in Epidermal Keratinocytes Triggers Atopic Dermatitis-Like Skin Inflammatory Responses in Adult Mice

PubMed Central

Guha, Gunjan; Li, Shan; Kyrylkova, Kateryna; Kioussi, Chrissa; Leid, Mark; Ganguli-Indra, Gitali; Indra, Arup K.

2012-01-01

Background Ctip2 is crucial for epidermal homeostasis and protective barrier formation in developing mouse embryos. Selective ablation of Ctip2 in epidermis leads to increased transepidermal water loss (TEWL), impaired epidermal proliferation, terminal differentiation, as well as altered lipid composition during development. However, little is known about the role of Ctip2 in skin homeostasis in adult mice. Methodology/Principal Findings To study the role of Ctip2 in adult skin homeostasis, we utilized Ctip2ep−/− mouse model in which Ctip2 is selectively deleted in epidermal keratinocytes. Measurement of TEWL, followed by histological, immunohistochemical, and RT-qPCR analyses revealed an important role of Ctip2 in barrier maintenance and in regulating adult skin homeostasis. We demonstrated that keratinocytic ablation of Ctip2 leads to atopic dermatitis (AD)-like skin inflammation, characterized by alopecia, pruritus and scaling, as well as extensive infiltration of immune cells including T lymphocytes, mast cells, and eosinophils. We observed increased expression of T-helper 2 (Th2)-type cytokines and chemokines in the mutant skin, as well as systemic immune responses that share similarity with human AD patients. Furthermore, we discovered that thymic stromal lymphopoietin (TSLP) expression was significantly upregulated in the mutant epidermis as early as postnatal day 1 and ChIP assay revealed that TSLP is likely a direct transcriptional target of Ctip2 in epidermal keratinocytes. Conclusions/Significance Our data demonstrated a cell-autonomous role of Ctip2 in barrier maintenance and epidermal homeostasis in adult mice skin. We discovered a crucial non-cell autonomous role of keratinocytic Ctip2 in suppressing skin inflammatory responses by regulating the expression of Th2-type cytokines. It is likely that the epidermal hyperproliferation in the Ctip2-lacking epidermis may be secondary to the compensatory response of the adult epidermis that is defective in barrier functions. Our results establish an initiating role of epidermal TSLP in AD pathogenesis via a novel repressive regulatory mechanism enforced by Ctip2. PMID:23284675

MATRIX METALLOPROTEINS (MMP)-MEDIATED PHOSPHORYLATION OF THE EPIDERMAL GROWTH FACTOR RECEPTOR (EGFR) IN HUMAN AIRWAY EPITHELIAL CELLS (HAEC) EXPOSED TO ZINC (ZN)

EPA Science Inventory

Matrix Metalloproteinase (MMP)-Mediated Phosphorylation of The Epidermal Growth Factor Receptor (EGFR) in Human Airway Epithelial Cells (HAEC) Exposed to Zinc (Zn)
Weidong Wu, James M. Samet, Robert Silbajoris, Lisa A. Dailey, Lee M. Graves, and Philip A. Bromberg
Center fo...

Isolation of epidermal cells and cDNA cloning of TNF decoy receptor 3 of conger eel, Conger myriaster.

PubMed

Tsutsui, Shigeyuki; Yoshino, Yuko; Matsui, Saho; Nakamura, Osamu; Muramoto, Koji; Watanabe, Tasuku

2008-03-01

By using EDTA and a trypsin solution, we established a method for isolating the epidermal cells of the conger eel, Conger myriaster. We then identified TNF decoy receptor (DcR) cDNA in the species from a suppression subtractive hybridization library prepared from the epidermal cells stimulated with LPS. The full-length cDNA of conger TNF DcR (conDcR) consisted of 1479 base pairs, and the protein comprised 286 amino acid residues. Phylogenetic analysis indicated that conDcR was clustered into a DcR3 branch. ConDcR is likely to act as an important immune-regulating factor in inhibiting the apoptosis-inducing effect of TNF in the skin of conger eel.

Ion fluxes across the pitcher walls of three Bornean Nepenthes pitcher plant species: flux rates and gland distribution patterns reflect nitrogen sequestration strategies.

PubMed

Moran, Jonathan A; Hawkins, Barbara J; Gowen, Brent E; Robbins, Samantha L

2010-03-01

Nepenthes pitcher plant species differ in their prey capture strategies, prey capture rates, and pitcher longevity. In this study, it is investigated whether or not interspecific differences in nutrient sequestration strategy are reflected in the physiology and microstructure of the pitchers themselves. Using a non-invasive technique (MIFE), ion fluxes in pitchers of Nepenthes ampullaria Jack, Nepenthes bicalcarata Hook.f., and Nepenthes rafflesiana Jack were measured. Scanning electron microscopy was also used to characterize the distribution of glandular and other structures on the inner pitcher walls. The results demonstrate that nutrient sequestration strategy is indeed mirrored in pitcher physiology and microstructure. Species producing long-lived pitchers with low prey capture rates (N. ampullaria, N. bicalcarata) showed lower rates of NH(4)(+) uptake than N. rafflesiana, a species producing short-lived pitchers with high capture rates. Crucially, species dependent upon aquatic commensals (N. ampullaria, N. bicalcarata) actively manipulated H(+) fluxes to maintain less acid pitcher fluid than found in 'typical' species; in addition, these species lacked the lunate cells and epicuticular waxes characteristic of 'typical' insectivorous congeners. An unexpected finding was that ion fluxes occurred in the wax-covered, non-glandular zones in N. rafflesiana. The only candidates for active transport of aqueous ions in these zones appear to be the epidermal cells lying beneath the lunate cells, as these are the only sites not visibly coated with epicuticular waxes.

Ion fluxes across the pitcher walls of three Bornean Nepenthes pitcher plant species: flux rates and gland distribution patterns reflect nitrogen sequestration strategies

PubMed Central

Moran, Jonathan A.; Hawkins, Barbara J.; Gowen, Brent E.; Robbins, Samantha L.

2010-01-01

Nepenthes pitcher plant species differ in their prey capture strategies, prey capture rates, and pitcher longevity. In this study, it is investigated whether or not interspecific differences in nutrient sequestration strategy are reflected in the physiology and microstructure of the pitchers themselves. Using a non-invasive technique (MIFE), ion fluxes in pitchers of Nepenthes ampullaria Jack, Nepenthes bicalcarata Hook.f., and Nepenthes rafflesiana Jack were measured. Scanning electron microscopy was also used to characterize the distribution of glandular and other structures on the inner pitcher walls. The results demonstrate that nutrient sequestration strategy is indeed mirrored in pitcher physiology and microstructure. Species producing long-lived pitchers with low prey capture rates (N. ampullaria, N. bicalcarata) showed lower rates of NH4+ uptake than N. rafflesiana, a species producing short-lived pitchers with high capture rates. Crucially, species dependent upon aquatic commensals (N. ampullaria, N. bicalcarata) actively manipulated H+ fluxes to maintain less acid pitcher fluid than found in ‘typical’ species; in addition, these species lacked the lunate cells and epicuticular waxes characteristic of ‘typical’ insectivorous congeners. An unexpected finding was that ion fluxes occurred in the wax-covered, non-glandular zones in N. rafflesiana. The only candidates for active transport of aqueous ions in these zones appear to be the epidermal cells lying beneath the lunate cells, as these are the only sites not visibly coated with epicuticular waxes. PMID:20150519

Biological functions of proline in morphogenesis and osmotolerance revealed in antisense transgenic Arabidopsis thaliana.

PubMed

Nanjo, T; Kobayashi, M; Yoshiba, Y; Sanada, Y; Wada, K; Tsukaya, H; Kakubari, Y; Yamaguchi-Shinozaki, K; Shinozaki, K

1999-04-01

Many organisms, including higher plants, accumulate free proline (Pro) in response to osmotic stress. Although various studies have focused on the ability of Pro as a compatible osmolyte involved in osmotolerance, its specific role throughout plant growth is still unclear. It has been reported that Pro is synthesized from Glu catalyzed by a key enzyme, delta 1-pyrroline-5-carboxylate synthetase (P5CS), in plants. To elucidate essential roles of Pro, we generated antisense transgenic Arabidopsis plants with a P5CS cDNA. Several transgenics accumulated Pro at a significantly lower level than wild-type plants, providing direct evidence for a key role of P5CS in Pro production in Arabidopsis. These antisense transgenics showed morphological alterations in leaves and a defect in elongation of inflorescences. Furthermore, transgenic leaves were hypersensitive to osmotic stress. Microscopic analysis of transgenic leaves, in which the mutated phenotype clearly occurred, showed morphological abnormalities of epidermal and parenchymatous cells and retardation of differentiation of vascular systems. These phenotypes were suppressed by exogenous L-Pro but not by D-Pro or other Pro analogues. In addition, Pro deficiency did not broadly affect all proteins but specifically affected structural proteins of cell walls in the antisense transgenic plants. These results indicate that Pro is not just an osmoregulator in stressed plants but has a unique function involved in osmotolerance as well as in morphogenesis as a major constituent of cell wall structural proteins in plants.

Sulfur Mustard (SM) Lesions in Organ-Cultured Human Skin: Markers of Injury and Inflammatory Mediators

DTIC Science & Technology

1990-04-16

18. SUB3ECT TERMS (oont’d) epidermal injury organ culture •ranuaear vacuoles C-leucine incorpora’tion by full-thickness human akin explants hi stamine ...mast- cell degranulation prostaglandin E2 lysobomal enzymes: acid phosphatase, B-glucuronidase, 0-galactcsidase, lysozyme and lactic dehydrogenase...that histamline (from local mast cells ), and PA and POgk (probably from mast cells and epidermal cells ) are s3e of the early mediators of the inflmma

Cell water potential, osmotic potential, and turgor in the epidermis and mesophyll of transpiring leaves : Combined measurements with the cell pressure probe and nanoliter osmometer.

PubMed

Nonami, H; Schulze, E D

1989-01-01

Water potential, osmotic potential and turgor measurements obtained by using a cell pressure probe together with a nanoliter osmometer were compared with measurements obtained with an isopiestic psychrometer. Both types of measurements were conducted in the mature region of Tradescantia virginiana L. leaves under non-transpiring conditions in the dark, and gave similar values of all potentials. This finding indicates that the pressure probe and the osmometer provide accurate measurements of turgor, osmotic potentials and water potentials. Because the pressure probe does not require long equilibration times and can measure turgor of single cells in intact plants, the pressure probe together with the osmometer was used to determine in-situ cell water potentials, osmotic potentials and turgor of epidermal and mesophyll cells of transpiring leaves as functions of stomatal aperture and xylem water potential. When the xylem water potential was-0.1 MPa, the stomatal aperture was at its maximum, but turgor of both epidermal and mesophyll cells was relatively low. As the xylem water potential decreased, the stomatal aperture became gradually smaller, whereas turgor of both epidermal and mesophyll cells first increased and afterward decreased. Water potentials of the mesophyll cells were always lower than those of the epidermal cells. These findings indicate that evaporation of water is mainly occurring from mesophyll cells and that peristomatal transpiration could be less important than it has been proposed previously, although peristomatal transpiration may be directly related to regulation of turgor in the guard cells.

Regulators of floral fragrance production and their target genes in petunia are not exclusively active in the epidermal cells of petals.

PubMed

Van Moerkercke, Alex; Galván-Ampudia, Carlos S; Verdonk, Julian C; Haring, Michel A; Schuurink, Robert C

2012-05-01

In which cells of the flower volatile biosynthesis takes place is unclear. In rose and snapdragon, some enzymes of the volatile phenylpropanoid/benzenoid pathway have been shown to be present in the epidermal cells of petals. It is therefore generally believed that the production of these compounds occurs in these cells. However, whether the entire pathway is active in these cells and whether it is exclusively active in these cells remains to be proven. Cell-specific transcription factors activating these genes will determine in which cells they are expressed. In petunia, the transcription factor EMISSION OF BENZENOIDS II (EOBII) activates the ODORANT1 (ODO1) promoter and the promoter of the biosynthetic gene isoeugenol synthase (IGS). The regulator ODO1 in turn activates the promoter of the shikimate gene 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). Here the identification of a new target gene of ODO1, encoding an ABC transporter localized on the plasma membrane, PhABCG1, which is co-expressed with ODO1, is described. PhABCG1 expression is up-regulated in petals overexpressing ODO1 through activation of the PhABCG1 promoter. Interestingly, the ODO1, PhABCG1, and IGS promoters were active in petunia protoplasts originating from both epidermal and mesophyll cell layers of the petal, suggesting that the volatile phenylpropanoid/benzenoid pathway in petunia is active in these different cell types. Since volatile release occurs from epidermal cells, trafficking of (volatile) compounds between cell layers must be involved, but the exact function of PhABCG1 remains to be resolved.

Distribution of calmodulin in pea seedlings: immunocytochemical localization in plumules and root apices

NASA Technical Reports Server (NTRS)

Dauwalder, M.; Roux, S. J.; Hardison, L.

1986-01-01

Immunofluorescence techniques have been used to study the distribution of calmodulin in several tissues in young etiolated pea (Pisum sativum L.) seedlings. A fairly uniform staining was seen in the nucleoplasm and background cytoplasm of most cell types. Cell walls and nucleoli were not stained. In addition, patterned staining reactions were seen in many cells. In cells of the plumule, punctate staining of the cytoplasm was common, and in part this stain appeared to be associated with the plastids. A very distinctive staining of amyloplasts was seen in the columella of the root cap. Staining associated with cytoskeletal elements could be shown in division stages. By metaphase, staining of the spindle region was quite evident. In epidermal cells of the stem and along the underside of the leaf there was an intense staining of the vacuolar contents. Guard cells lacked this vacuolar stain. Vacuolar staining was sometimes seen in cells of the stele, but the most distinctive pattern in the stele was associated with young conducting cells of the xylem. These staining patterns are consistent with the idea that the interactions of plastids and the cytoskeletal may be one of the Ca(2+)-mediated steps in the response of plants to environmental stimuli. Nuclear functions may also be controlled, at least in part, by Ca2+.

Identification of heparin-binding EGF-like growth factor as a target in intercellular regulation of epidermal basal cell growth by suprabasal retinoic acid receptors.

PubMed Central

Xiao, J H; Feng, X; Di, W; Peng, Z H; Li, L A; Chambon, P; Voorhees, J J

1999-01-01

The role of retinoic acid receptors (RARs) in intercellular regulation of cell growth was assessed by targeting a dominant-negative RARalpha mutant (dnRARalpha) to differentiated suprabasal cells of mouse epidermis. dnRARalpha lacks transcriptional activation but not DNA-binding and receptor dimerization functions. Analysis of transgenic mice revealed that dnRARalpha dose-dependently impaired induction of basal cell proliferation and epidermal hyperplasia by all-trans RA (tRA). dnRARalpha formed heterodimers with endogenous retinoid X receptor-alpha (RXRalpha) over RA response elements in competition with remaining endogenous RARgamma-RXRalpha heterodimers, and dose-dependently impaired retinoid-dependent gene transcription. To identify genes regulated by retinoid receptors and involved in cell growth control, we analyzed the retinoid effects on expression of the epidermal growth factor (EGF) receptor, EGF, transforming growth factor-alpha, heparin-binding EGF-like growth factor (HB-EGF) and amphiregulin genes. In normal epidermis, tRA rapidly and selectively induced expression of HB-EGF but not the others. This induction occurred exclusively in suprabasal cells. In transgenic epidermis, dnRARalpha dose-dependently inhibited tRA induction of suprabasal HB-EGF and subsequent basal cell hyperproliferation. Together, our observations suggest that retinoid receptor heterodimers located in differentiated suprabasal cells mediate retinoid induction of HB-EGF, which in turn stimulates basal cell growth via intercellular signaling. These events may underlie retinoid action in epidermal regeneration during wound healing. PMID:10075925

Efficacy of chemotherapy after first-line gefitinib therapy in EGFR mutation-positive advanced non-small cell lung cancer-data from a randomized Phase III study comparing gefitinib with carboplatin plus paclitaxel (NEJ002).

PubMed

Miyauchi, Eisaku; Inoue, Akira; Kobayashi, Kunihiko; Maemondo, Makoto; Sugawara, Shunichi; Oizumi, Satoshi; Isobe, Hiroshi; Gemma, Akihiko; Saijo, Yasuo; Yoshizawa, Hirohisa; Hagiwara, Koichi; Nukiwa, Toshihiro

2015-07-01

Epidermal growth factor receptor tyrosine kinase inhibitors are effective as first-line therapy for advanced non-small cell lung cancer patients harboring epidermal growth factor receptor mutations. However, it is unknown whether second-line platinum-based chemotherapy after epidermal growth factor receptor tyrosine kinase inhibitor therapy could lead to better outcomes. We evaluated the efficacy of second-line platinum-based chemotherapy after gefitinib for advanced non-small cell lung cancers harboring epidermal growth factor receptor mutations (the NEJ002 study). Seventy-one non-small cell lung cancers, treated with gefitinib as first-line therapy and then receiving platinum-based chemotherapy as second-line therapy were evaluated in NEJ002. Patients were evaluated for antitumor response to second-line chemotherapy by computed tomography according to the criteria of the Response Evaluation Criteria in Solid Tumors group (version 1.0). Of the 71 patients receiving platinum-based chemotherapy after first-line gefitinib, a partial response was documented in 25.4% (18/71), stable disease in 43.7% (31/71) and progression of disease in 21.1% (15/71). The objective response and disease control rates were 25.4% (18/71) and 69% (49/71), respectively. There was no significant difference between first- and second-line chemotherapy in objective response and disease control rates for advanced non-small cell lung cancer harboring activating epidermal growth factor receptor mutations. In the analysis of epidermal growth factor receptor mutation types, the objective responses of deletions in exon 19 and a point mutation in exon 21 (L858R) were 27.3% (9/33) and 28.1% (9/32), respectively, but these differences between objective response rates were not significant. The efficacy of second-line platinum-based chemotherapy followed at progression by gefitinib was similar to first-line platinum-based chemotherapy, and epidermal growth factor receptor mutation types did not influence the efficacy of second-line platinum-based chemotherapy. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Targeted inactivation of integrin-linked kinase in hair follicle stem cells reveals an important modulatory role in skin repair after injury.

PubMed

Nakrieko, Kerry-Ann; Rudkouskaya, Alena; Irvine, Timothy S; D'Souza, Sudhir J A; Dagnino, Lina

2011-07-15

Integrin-linked kinase (ILK) is key for normal epidermal morphogenesis, but little is known about its role in hair follicle stem cells and epidermal regeneration. Hair follicle stem cells are important contributors to newly formed epidermis following injury. We inactivated the Ilk gene in the keratin 15--expressing stem cell population of the mouse hair follicle bulge. Loss of ILK expression in these cells resulted in impaired cutaneous wound healing, with substantially decreased wound closure rates. ILK-deficient stem cells produced very few descendants that moved toward the epidermal surface and into the advancing epithelium that covers the wound. Furthermore, those few mutant cells that homed in the regenerated epidermis exhibited a reduced residence time. Paradoxically, ILK-deficient bulge stem cells responded to anagen growth signals and contributed to newly regenerated hair follicles during this phase of hair follicle growth. Thus ILK plays an important modulatory role in the normal contribution of hair follicle stem cell progeny to the regenerating epidermis following injury.

Targeted inactivation of integrin-linked kinase in hair follicle stem cells reveals an important modulatory role in skin repair after injury

PubMed Central

Nakrieko, Kerry-Ann; Rudkouskaya, Alena; Irvine, Timothy S.; D'souza, Sudhir J. A.; Dagnino, Lina

2011-01-01

Integrin-linked kinase (ILK) is key for normal epidermal morphogenesis, but little is known about its role in hair follicle stem cells and epidermal regeneration. Hair follicle stem cells are important contributors to newly formed epidermis following injury. We inactivated the Ilk gene in the keratin 15–expressing stem cell population of the mouse hair follicle bulge. Loss of ILK expression in these cells resulted in impaired cutaneous wound healing, with substantially decreased wound closure rates. ILK-deficient stem cells produced very few descendants that moved toward the epidermal surface and into the advancing epithelium that covers the wound. Furthermore, those few mutant cells that homed in the regenerated epidermis exhibited a reduced residence time. Paradoxically, ILK-deficient bulge stem cells responded to anagen growth signals and contributed to newly regenerated hair follicles during this phase of hair follicle growth. Thus ILK plays an important modulatory role in the normal contribution of hair follicle stem cell progeny to the regenerating epidermis following injury. PMID:21593206

PW1 gene/paternally expressed gene 3 (PW1/Peg3) identifies multiple adult stem and progenitor cell populations

PubMed Central

Besson, Vanessa; Smeriglio, Piera; Wegener, Amélie; Relaix, Frédéric; Nait Oumesmar, Brahim; Sassoon, David A.; Marazzi, Giovanna

2011-01-01

A variety of markers are invaluable for identifying and purifying stem/progenitor cells. Here we report the generation of a murine reporter line driven by Pw1 that reveals cycling and quiescent progenitor/stem cells in all adult tissues thus far examined, including the intestine, blood, testis, central nervous system, bone, skeletal muscle, and skin. Neurospheres generated from the adult PW1-reporter mouse show near 100% reporter-gene expression following a single passage. Furthermore, epidermal stem cells can be purified solely on the basis of reporter-gene expression. These cells are clonogenic, repopulate the epidermal stem-cell niches, and give rise to new hair follicles. Finally, we demonstrate that only PW1 reporter-expressing epidermal cells give rise to follicles that are capable of self-renewal following injury. Our data demonstrate that PW1 serves as an invaluable marker for competent self-renewing stem cells in a wide array of adult tissues, and the PW1-reporter mouse serves as a tool for rapid stem cell isolation and characterization. PMID:21709251

De novo epidermal regeneration using human eccrine sweat gland cells: higher competence of secretory over absorptive cells.

PubMed

Pontiggia, Luca; Biedermann, Thomas; Böttcher-Haberzeth, Sophie; Oliveira, Carol; Braziulis, Erik; Klar, Agnieszka S; Meuli-Simmen, Claudia; Meuli, Martin; Reichmann, Ernst

2014-06-01

In our previous work, we showed that human sweat gland-derived epithelial cells represent an alternative source of keratinocytes to grow a near normal autologous epidermis. The role of subtypes of sweat gland cells in epidermal regeneration and maintenance remained unclear. In this study, we compare the regenerative potential of both secretory and absorptive sweat gland cell subpopulations. We demonstrate the superiority of secretory over absorptive cells in forming a new epidermis on two levels: first, the proliferative and colony-forming efficiencies in vitro are significantly higher for secretory cells (SCs), and second, SCs show a higher frequency of successful epidermis formation as well as an increase in the thickness of the formed epidermis in the in vitro and in vivo functional analyses using a 3D dermo-epidermal skin model. However, the ability of forming functional skin substitutes is not limited to SCs, which supports the hypothesis that multiple subtypes of sweat gland epithelial cells hold regenerative properties, while the existence and exact localization of a keratinocyte stem cell population in the human eccrine sweat gland remain elusive.

Topical grape seed proanthocyandin extract reduces sunburn cells and mutant p53 positive epidermal cell formation, and prevents depletion of Langerhans cells in an acute sunburn model.

PubMed

Yuan, Xiao-Ying; Liu, Wei; Hao, Jian-Chun; Gu, Wei-Jie; Zhao, Yan-Shuang

2012-01-01

The purpose of this study was to investigate whether grape seed proanthocyanidin extract (GSPE) can provide photoprotection against ultraviolet (UV) irradiation. Study has shown that GSPE is a natural oxidant, and is used in many fields such as ischemia-reperfusion injury, chronic pancreatitis, and even cancer. However, the effect of GSPE on UV irradiation is as yet unknown. Cutaneous areas on the backs of normal volunteers were untreated or treated with GSPE solutions or vehicles 30 min before exposure to two minimal erythema doses (MED) of solar simulated radiation. Cutaneous areas at different sites were examined histologically for the number of sunburn cells, or immunohistochemically for Langerhans cells and mutant p53 epidermal cells. On histological and immunohistochemical examination, skin treated with GSPE before UV radiation showed fewer sunburn cells and mutant p53-positive epidermal cells and more Langerhans cells compared with skin treated with 2-MED UV radiation only (p<0.001, p<0.001, and p<0.01, respectively). GSPE may be a possible preventive agent for photoprotection.

Effects of icotinib, a novel epidermal growth factor receptor tyrosine kinase inhibitor, in EGFR-mutated non-small cell lung cancer.

PubMed

Yang, Guangdie; Yao, Yinan; Zhou, Jianya; Zhao, Qiong

2012-06-01

Epidermal growth factor receptor (EGFR) is one of the most promising targets for non-small cell lung cancer (NSCLC). Our study demonstrated the antitumor effects of icotinib hydrochloride, a highly selective epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKI), in two EGFR-mutated lung cancer cell lines compared to A549, a cell line without EGFR mutations. We incubated PC-9 and HCC827 human lung cancer cell lines both with (E746-A750) mutations with various concentrations of icotinib and gefitinib for 48 h. Cell proliferation and migration were determined using a real-time cell invasion and migration assay and cytotoxicity assay. Apoptosis was assessed by measuring Annexin V staining using flow cytometry. The antitumor effects of icotinib compared to gefitinib were similar and were most effective in reducing the proliferation of EGFR-mutated cells compared to non-mutated controls. Our results suggest the possibility of icotinib as a new therapeutic agent of EGFR-mutated cancer cells, which has the potential to be used in the first-line treatment of EGFR-mutated NSCLC.

Protein profiling of single epidermal cell types from Arabidopsis thaliana using surface-enhanced laser desorption and ionization technology.

PubMed

Ebert, Berit; Melle, Christian; Lieckfeldt, Elke; Zöller, Daniela; von Eggeling, Ferdinand; Fisahn, Joachim

2008-08-25

Here, we describe a novel approach for investigating differential protein expression within three epidermal cell types. In particular, 3000 single pavement, basal, and trichome cells from leaves of Arabidopsis thaliana were harvested by glass micro-capillaries. Subsequently, these single cell samples were joined to form pools of 100 individual cells and analyzed using the ProteinChip technology; SELDI: surface-enhanced laser desorption and ionization. As a result, numerous protein signals that were differentially expressed in the three epidermal cell types could be detected. One of these proteins was characterized by tryptical digestion and subsequent identification via tandem quadrupole-time of flight (Q-TOF) mass spectrometry. Down regulation of this sequenced small subunit precursor of ribulose-1,5 bisphosphate carboxylase(C) oxygenase(O) (RuBisCo) in trichome and basal cells indicates the sink status of these cell types that are located on the surface of A. thaliana source leaves. Based on the obtained protein profiles, we suggest a close functional relationship between basal and trichome cells at the protein level.

Cervi cornus Colla (deer antler glue) induce epidermal differentiation in the reconstruction of skin equivalents.

PubMed

Choi, H-R; Nam, K-M; Kim, D-S; Huh, C-H; Na, J-I; Park, K-C

2013-06-01

In the reconstruction of skin equivalents (SEs), keratinocyte differentiation is important because epidermal differentiation is closely related with barrier function. The aim of this study was to investigate the effects of Cervi cornus Colla (CCC) on the stem cell activity and epidermal differentiation in the reconstruction of skin equivalent. Four different models were constructed according to different composition of dermal substitute. Results showed similar morphologic findings when hyaluronic acid (HA) and/or CCC was added. But, immunohistochemical staining showed that p63 was significantly increased by addition of HA and/or CCC. Increased staining of integrin α6 and β1 was variably observed when HA and/or CCC was added to make dermal substitute. These finding showed that addition of HA and/or CCC may affect the stem cell activity in the reconstruction of skin. Furthermore, filaggrin expression was much increased when CCC was added. It showed that epidermal differentiation was significantly improved by addition of CCC. In conclusion, simultaneous presence of HA and CCC contributed to the stem cell activity and epidermal differentiation in the reconstruction of SE. Legislation in the EU prohibits marketing cosmetics and personal care products that contain constituents that have been examined through animal experiments. To avoid these limitations, SEs can be used for testing the safety or the efficacy of cosmetic ingredients. Therefore, our results showed that combined use of HA and CCC can be helpful for the reconstruction of SE with good stem cell activity and epidermal differentiation. © 2013 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Indirubin, an acting component of indigo naturalis, inhibits EGFR activation and EGF-induced CDC25B gene expression in epidermal keratinocytes.

PubMed

Hsieh, Wan-Ling; Lin, Yin-Ku; Tsai, Chi-Neu; Wang, Ta-Min; Chen, Tzu-Ya; Pang, Jong-Hwei S

2012-08-01

Topical indigo naturalis ointment is clinically proved to be an effective therapy for plaque-type psoriasis. Indirubin, as the active component of indigo naturalis, inhibits cell proliferation of epidermal keratinocytes. However, the detailed underlying mechanism is not fully understood. To further investigate the anti-proliferating effects of indigo naturalis and indirubin on epidermal keratinocytes. The decreased expression of CDC25B in indigo naturalis- or indirubin-treated epidermal keratinocytes, as revealed by cDNA microarray analysis, was studied. The CDC25B expression was examined under different serum concentrations and compared between primary and immortalized keratinocytes. The activation of EGFR and the effect of EGF on the cell proliferation and CDC25B expression were also investigated in epidermal keratinocytes. RT/real-time PCR and western blot method were used to analyze the CDC25B expression at the mRNA and protein levels, respectively. Indigo naturalis and indirubin were confirmed to down-regulate CDC25B expression significantly at both the mRNA and protein levels. The growth-dependent expression of CDC25B was demonstrated by the increased expression in serum-stimulated and immortalized keratinocytes. The activation of EGF receptor, known to be highly expressed in psoriatic lesions, was inhibited by indigo naturalis or indirubin. The cell proliferation and CDC25B expression of epidermal keratinocytes were induced by EGF alone and confirmed to be inhibited by indigo naturalis or indirubin. Except being a common therapeutic target in various cancers, CDC25B also plays an important role in the hyper-proliferation of epidermal keratinocytes which can be suppressed by anti-psoriatic drug indigo naturalis and its component, indirubin. Copyright © 2012 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.

Delphinidin, a dietary antioxidant, induces human epidermal keratinocyte differentiation but not apoptosis: studies in submerged and three-dimensional epidermal equivalent models.

PubMed

Chamcheu, Jean Christopher; Afaq, Farrukh; Syed, Deeba N; Siddiqui, Imtiaz A; Adhami, Vaqar M; Khan, Naghma; Singh, Sohinderjit; Boylan, Brendan T; Wood, Gary S; Mukhtar, Hasan

2013-05-01

Delphinidin (Del), [3,5,7,3'-,4'-,5'-hexahydroxyflavylium], an anthocyanidin and a potent antioxidant abundantly found in pigmented fruits and vegetables exhibits proapoptotic effects in many cancer cells. Here, we determined the effect of Del on growth, apoptosis and differentiation of normal human epidermal keratinocytes (NHEKs) in vitro in submerged cultures and examined its effects in a three-dimensional (3D) epidermal equivalent (EE) model that permits complete differentiation reminiscent of in vivo skin. Treatment of NHEKs with Del (10-40 μm; 24-48 h) significantly enhanced keratinocyte differentiation. In Del-treated cells, there was marked increase in human involucrin (hINV) promoter activity with simultaneous increase in the mRNA and protein expressions of involucrin and other epidermal differentiation markers including procaspase-14 and transglutaminase-1 (TGM1), but without any effect on TGM2. Del treatment of NHEKs was associated with minimal decrease in cell viability, which was not associated with apoptosis as evident by lack of modulation of caspases, apoptosis-related proteins including Bcl-2 family of proteins and poly(ADP-ribose) polymerase cleavage. To establish the in vivo relevance of our observations in submerged cultures, we then validated these effects in a 3D EE model, where Del was found to significantly enhance cornification and increase the protein expression of cornification markers including caspase-14 and keratin 1. For the first time, we show that Del induces epidermal differentiation using an experimental system that closely mimics in vivo human skin. These observations suggest that Del could be a useful agent for dermatoses associated with epidermal barrier defects including aberrant keratinization, hyperproliferation or inflammation observed in skin diseases like psoriasis and ichthyoses. © 2013 John Wiley & Sons A/S.

The DP-1 transcription factor is required for keratinocyte growth and epidermal stratification.

PubMed

Chang, Wing Y; Bryce, Dawn M; D'Souza, Sudhir J A; Dagnino, Lina

2004-12-03

The epidermis is a stratified epithelium constantly replenished through the ability of keratinocytes in its basal layer to proliferate and self-renew. The epidermis arises from a single-cell layer ectoderm during embryogenesis. Large proliferative capacity is central to ectodermal cell and basal keratinocyte function. DP-1, a heterodimeric partner of E2F transcription factors, is highly expressed in the ectoderm and all epidermal layers during embryogenesis. To investigate the role of DP-1 in epidermal morphogenesis, we inhibited DP-1 activity through exogenous expression of a dominant-negative mutant (dnDP-1). Expression of the dnDP-1 mutant interferes with binding of E2F/DP-1 heterodimers to DNA and inhibits DNA replication, as well as cyclin A mRNA and protein expression. Chromatin immunoprecipitation analysis demonstrated that the cyclin A promoter is predominantly bound in proliferating keratinocytes by complexes containing E2F-3 and E2F-4. Thus, the mechanisms of decreased expression of cyclin A in the presence of dnDP-1 seem to involve inactivation of DP-1 complexes containing E2F-3 and E2F-4. To assess the consequences on epidermal morphogenesis of inhibiting DP-1 activity, we expressed dnDP-1 in rat epithelial keratinocytes in organotypic culture and observed that DP-1 inhibition negatively affected stratification of these cells. Likewise, expression of dnDP-1 in embryonic ectoderm explants produced extensive disorganization of subsequently formed epidermal basal and suprabasal layers, interfering with normal epidermal formation. We conclude that DP-1 activity is required for normal epidermal morphogenesis and ectoderm-to-epidermis transition.

Transgenic expression of human amphiregulin in mouse skin: inflammatory epidermal hyperplasia and enlarged sebaceous glands.

PubMed

Li, Yong; Stoll, Stefan W; Sekhon, Sahil; Talsma, Caroline; Camhi, Maya I; Jones, Jennifer L; Lambert, Sylviane; Marley, Hue; Rittié, Laure; Grachtchouk, Marina; Fritz, Yi; Ward, Nicole L; Elder, James T

2016-03-01

To explore the role of amphiregulin in inflammatory epidermal hyperplasia, we overexpressed human AREG (hAREG) in FVB/N mice using a bovine K5 promoter. A construct containing AREG coding sequences flanked by 5' and 3' untranslated region sequences (AREG-UTR) led to a >10-fold increase in hAREG expression compared to an otherwise-identical construct containing only the coding region (AREG-CDR). AREG-UTR mice developed tousled, greasy fur as well as elongated nails and thickened, erythematous tail skin. No such phenotype was evident in AREG-CDR mice. Histologically, AREG-UTR mice presented with marked epidermal hyperplasia of tail skin (2.1-fold increase in epidermal thickness with a 9.5-fold increase in Ki-67(+) cells) accompanied by significantly increased CD4+ T-cell infiltration. Dorsal skin of AREG-UTR mice manifested lesser but still significant increases in epidermal thickness and keratinocyte hyperplasia. AREG-UTR mice also developed marked and significant sebaceous gland enlargement, with corresponding increases in Ki-67(+) cells. To determine the response of AREG-UTR animals to a pro-inflammatory skin challenge, topical imiquimod (IMQ) or vehicle cream was applied to dorsal and tail skin. IMQ increased dorsal skin thickness similarly in both AREG-UTR and wild type mice (1.7- and 2.2-fold vs vehicle, P < 0.001 each), but had no such effect on tail skin. These results confirm that keratinocyte expression of hAREG elicits inflammatory epidermal hyperplasia, and are consistent with prior reports of tail epidermal hyperplasia and increased sebaceous gland size in mice expressing human epigen. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Probing the stochastic property of endoreduplication in cell size determination of Arabidopsis thaliana leaf epidermal tissue

PubMed Central

2017-01-01

Cell size distribution is highly reproducible, whereas the size of individual cells often varies greatly within a tissue. This is obvious in a population of Arabidopsis thaliana leaf epidermal cells, which ranged from 1,000 to 10,000 μm2 in size. Endoreduplication is a specialized cell cycle in which nuclear genome size (ploidy) is doubled in the absence of cell division. Although epidermal cells require endoreduplication to enhance cellular expansion, the issue of whether this mechanism is sufficient for explaining cell size distribution remains unclear due to a lack of quantitative understanding linking the occurrence of endoreduplication with cell size diversity. Here, we addressed this question by quantitatively summarizing ploidy profile and cell size distribution using a simple theoretical framework. We first found that endoreduplication dynamics is a Poisson process through cellular maturation. This finding allowed us to construct a mathematical model to predict the time evolution of a ploidy profile with a single rate constant for endoreduplication occurrence in a given time. We reproduced experimentally measured ploidy profile in both wild-type leaf tissue and endoreduplication-related mutants with this analytical solution, further demonstrating the probabilistic property of endoreduplication. We next extended the mathematical model by incorporating the element that cell size is determined according to ploidy level to examine cell size distribution. This analysis revealed that cell size is exponentially enlarged 1.5 times every endoreduplication round. Because this theoretical simulation successfully recapitulated experimentally observed cell size distributions, we concluded that Poissonian endoreduplication dynamics and exponential size-boosting are the sources of the broad cell size distribution in epidermal tissue. More generally, this study contributes to a quantitative understanding whereby stochastic dynamics generate steady-state biological heterogeneity. PMID:28926847

Heterogeneous fates and dynamic rearrangement of regenerative epidermis-derived cells during zebrafish fin regeneration.

PubMed

Shibata, Eri; Ando, Kazunori; Murase, Emiko; Kawakami, Atsushi

2018-04-13

The regenerative epidermis (RE) is a specialized tissue that plays an essential role in tissue regeneration. However, the fate of the RE during and after regeneration is unknown. In this study, we performed Cre- loxP -mediated cell fate tracking and revealed the fates of a major population of the RE cells that express fibronectin 1b ( fn1b ) during zebrafish fin regeneration. Our study showed that these RE cells are mainly recruited from the inter-ray epidermis, and that they follow heterogeneous cell fates. Early recruited cells contribute to initial wound healing and soon disappear by apoptosis, while the later recruited cells contribute to the regenerated epidermis. Intriguingly, many of these cells are also expelled from the regenerated tissue by a dynamic caudal movement of the epidermis over time, and in turn the loss of epidermal cells is replenished by a global self-replication of basal and suprabasal cells in fin. De-differentiation of non-basal epidermal cells into the basal epidermal cells did not occur during regeneration. Overall, our study reveals the heterogeneous fates of RE cells and a dynamic rearrangement of the epidermis during and after regeneration. © 2018. Published by The Company of Biologists Ltd.

Epidermal growth factor in alkali-burned corneal epithelial wound healing.

PubMed

Singh, G; Foster, C S

1987-06-15

We conducted a double-masked study to evaluate the effect of epidermal growth factor on epithelial wound healing and recurrent erosions in alkali-burned rabbit corneas. Epithelial wounds 10 mm in diameter healed completely under the influence of topical epidermal growth factor, whereas the control corneas did not resurface in the center. On reversal of treatment, the previously nonhealing epithelial defects healed when treated with topical epidermal growth factor eyedrops. Conversely, the epidermal growth factor-treated and resurfaced corneas developed epithelial defects when treatment was discontinued. Histopathologic examination disclosed hyperplastic epithelium growing over the damaged stroma laden with polymorphonuclear leukocytes when treated with epidermal growth factor eyedrops, but it did not adhere to the underlying tissue. Hydropic changes were seen intracellularly as well as between the epithelial cells and the stroma.

The mysterious human epidermal cell cycle, or an oncogene-induced differentiation checkpoint

PubMed Central

Gandarillas, Alberto

2012-01-01

Fifteen years ago, we reported that proto-oncogene MYC promoted differentiation of human epidermal stem cells, a finding that was surprising to the MYC and the skin research communities. MYC was one of the first human oncogenes identified, and it had been strongly associated with proliferation. However, it was later shown that MYC could induce apoptosis under low survival conditions. Currently, the notion that MYC promotes epidermal differentiation is widely accepted, but the cell cycle mechanisms that elicit this function remain unresolved. We have recently reported that keratinocytes respond to cell cycle deregulation and DNA damage by triggering terminal differentiation. This mechanism might constitute a homeostatic protection face to cell cycle insults. Here, I discuss recent and not-so-recent evidence suggesting the existence of a largely unexplored oncogene-induced differentiation response (OID) analogous to oncogene-induced apoptosis (OIA) or senescence (OIS). In addition, I propose a model for the role of the cell cycle in skin homeostasis maintenance and for the dual role of MYC in differentiation. PMID:23114621

Transcriptional Profiling of Ectoderm Specification to Keratinocyte Fate in Human Embryonic Stem Cells

PubMed Central

Tadeu, Ana Mafalda Baptista; Lin, Samantha; Hou, Lin; Chung, Lisa; Zhong, Mei; Zhao, Hongyu; Horsley, Valerie

2015-01-01

In recent years, several studies have shed light into the processes that regulate epidermal specification and homeostasis. We previously showed that a broad-spectrum γ–secretase inhibitor DAPT promoted early keratinocyte specification in human embryonic stem cells triggered to undergo ectoderm specification. Here, we show that DAPT accelerates human embryonic stem cell differentiation and induces expression of the ectoderm protein AP2. Furthermore, we utilize RNA sequencing to identify several candidate regulators of ectoderm specification including those involved in epithelial and epidermal development in human embryonic stem cells. Genes associated with transcriptional regulation and growth factor activity are significantly enriched upon DAPT treatment during specification of human embryonic stem cells to the ectoderm lineage. The human ectoderm cell signature identified in this study contains several genes expressed in ectodermal and epithelial tissues. Importantly, these genes are also associated with skin disorders and ectodermal defects, providing a platform for understanding the biology of human epidermal keratinocyte development under diseased and homeostatic conditions. PMID:25849374

Asymmetric distribution of Echinoid defines the epidermal leading edge during Drosophila dorsal closure

PubMed Central

Laplante, Caroline

2011-01-01

During Drosophila melanogaster dorsal closure, lateral sheets of embryonic epidermis assemble an actomyosin cable at their leading edge and migrate dorsally over the amnioserosa, converging at the dorsal midline. We show that disappearance of the homophilic cell adhesion molecule Echinoid (Ed) from the amnioserosa just before dorsal closure eliminates homophilic interactions with the adjacent dorsal-most epidermal (DME) cells, which comprise the leading edge. The resulting planar polarized distribution of Ed in the DME cells is essential for the localized accumulation of actin regulators and for actomyosin cable formation at the leading edge and for the polarized localization of the scaffolding protein Bazooka/PAR-3. DME cells with uniform Ed fail to assemble a cable and protrude dorsally, suggesting that the cable restricts dorsal migration. The planar polarized distribution of Ed in the DME cells thus provides a spatial cue that polarizes the DME cell actin cytoskeleton, defining the epidermal leading edge and establishing its contractile properties. PMID:21263031

Periostin contributes to epidermal hyperplasia in psoriasis common to atopic dermatitis

PubMed Central

Arima, Kazuhiko; Ohta, Shoichiro; Takagi, Atsushi; Shiraishi, Hiroshi; Masuoka, Miho; Ontsuka, Kanako; Suto, Hajime; Suzuki, Shoichi; Yamamoto, Ken-ichi; Ogawa, Masahiro; Simmons, Olga; Yamaguchi, Yukie; Toda, Shuji; Aihara, Michiko; Conway, Simon J.; Ikeda, Shigaku; Izuhara, Kenji

2016-01-01

Background Epidermal hyperplasia is a histological hallmark observed in both atopic dermatitis (AD) and psoriasis, although the clinical features and the underlying immunological disorders of these diseases are different. We previously showed that periostin, a matricellular protein, plays a critical role in epidermal hyperplasia in AD, using a mouse model and a 3-dimensional organotypic coculture system. In this study, we explore the hypothesis that periostin is involved in epidermal hyperplasia in psoriasis. Methods To examine expression of periostin in psoriasis patients, we performed immunohistochemical analysis on skin biopsies from six such patients. To investigate periostin’s role in the pathogenesis of psoriasis, we evaluated periostin-deficient mice in a psoriasis mouse model induced by topical treatment with imiquimod (IMQ). Results Periostin was substantially expressed in the dermis of all investigated psoriasis patients. Epidermal hyperplasia induced by IMQ treatment was impaired in periostin-deficient mice, along with decreased skin swelling. However, upon treatment with IMQ, periostin deficiency did not alter infiltration of inflammatory cells such as neutrophils; production of IL-17, –22, or –23; or induction/expansion of IL-17– and IL-22–producing group 3 innate lymphoid cells. Conclusions Periostin plays an important role during epidermal hyperplasia in IMQ-induced skin inflammation, independently of the IL-23–IL-17/IL-22 axis. Periostin appears to be a mediator for epidermal hyperplasia that is common to AD and psoriasis. PMID:25572557

Epidermal ADAM17 maintains the skin barrier by regulating EGFR ligand–dependent terminal keratinocyte differentiation

PubMed Central

Cobzaru, Cristina; Triantafyllopoulou, Antigoni; Löffek, Stefanie; Horiuchi, Keisuke; Threadgill, David W.; Kurz, Thomas; van Rooijen, Nico; Bruckner-Tuderman, Leena

2012-01-01

ADAM17 (a disintegrin and metalloproteinase 17) is ubiquitously expressed and cleaves membrane proteins, such as epidermal growth factor receptor (EGFR) ligands, l-selectin, and TNF, from the cell surface, thus regulating responses to tissue injury and inflammation. However, little is currently known about its role in skin homeostasis. We show that mice lacking ADAM17 in keratinocytes (A17ΔKC) have a normal epidermal barrier and skin architecture at birth but develop pronounced defects in epidermal barrier integrity soon after birth and develop chronic dermatitis as adults. The dysregulated expression of epidermal differentiation proteins becomes evident 2 d after birth, followed by reduced transglutaminase (TGM) activity, transepidermal water loss, up-regulation of the proinflammatory cytokine IL-36α, and inflammatory immune cell infiltration. Activation of the EGFR was strongly reduced in A17ΔKC skin, and topical treatment of A17ΔKC mice with recombinant TGF-α significantly improved TGM activity and decreased skin inflammation. Finally, we show that mice lacking the EGFR in keratinocytes (EgfrΔKC) closely resembled A17ΔKC mice. Collectively, these results identify a previously unappreciated critical role of the ADAM17–EGFR signaling axis in maintaining the homeostasis of the postnatal epidermal barrier and suggest that this pathway could represent a good target for treatment of epidermal barrier defects. PMID:22565824

Therapeutic approach to mite-induced intractable dermatitis using novel immunomodulator FTY720 ointment (fingolimod) in NC/Nga mice.

PubMed

Tsuji, Takumi; Okuno, Satoshi; Kuroda, Ayano; Hamazaki, Junya; Chikami, Takuma; Sakurai, Sakura; Yoshida, Yuya; Banno, Rie; Fujita, Tetsuro; Kohno, Takeyuki

2016-04-01

The increasing incidence and prevalence of atopic dermatitis (AD) demands new therapeutic approaches for treating the disease. We investigated the therapeutic efficacy of immunomodulator FTY720 ointment (fingolimod) for mite-induced intractable AD using an NC/Nga mouse model. Female NC/Nga mice that developed severe AD were divided into four groups: (1) FTY720 (0.001% FTY720 ointment), (2) tacrolimus (tacrolimus hydrate ointment) (3) betamethasone (betamethasone ointment), and (4) ointment base (hydrophilic petrolatum), all of which received treatment six times per week. Therapeutic efficacy after two weeks was evaluated in terms of AD severity, histochemical observations (epidermal hypertrophy, mast cell accumulation, and CD3(+) T cell infiltration), transepidermal water loss (TEWL), and epidermal barrier function (filaggrin expression). Betamethasone treatment showed little effect, confirming that the AD was intractable. In the FTY720 group, AD improved significantly compared with the ointment base group, as did epidermal hypertrophy, mast cell accumulation, and CD3(+) T cell infiltration. In contrast, AD in the tacrolimus and betamethasone groups did not improve significantly, nor did epidermal hypertrophy or mast cell accumulation. Furthermore, in the FTY720 group, TEWL decreased significantly compared with the ointment base group, and filaggrin expression significantly increased compared with the betamethasone and ointment base groups. FTY720 ointment is a promising candidate for treatment of intractable AD. These findings also provide the first evidence that FTY720 ointment ameliorates epidermal barrier function. Copyright © 2015 Japanese Society of Allergology. Production and hosting by Elsevier B.V. All rights reserved.

Zebrafish grainyhead-like1 is a common marker of different non-keratinocyte epidermal cell lineages, which segregate from each other in a Foxi3-dependent manner

PubMed Central

JÄNICKE, MARTINA; RENISCH, BJÖRN; HAMMERSCHMIDT, MATTHIAS

2012-01-01

Grainyhead/CP2 transcription factor family members are widely conserved among the animal kingdom and have been implicated in different developmental processes. Thus far, nothing has been known about their roles in zebrafish. Here we identify seven zebrafish grainyhead-like (grhl) / cp2 genes, with focus on grhl1, which is expressed in the periderm and in epidermal ionocyte progenitors, but downregulated when ionocytes differentiate. In addition, expression was detected in other “non-keratinocyte” cell types of the epidermis, such as pvalb8-expressing cells, which according to our lineage tracing experiments are derived from the same pool of progenitor cells like keratinocytes and ionocytes. Antisense morpholino oligonucleotide-based loss-of-function analysis revealed that grhl1 is dispensable for the development and function of all investigated epidermal cell types, but required as a negative regulator of its own transcription during ionocyte differentiation. Knockdown of the transcription factor Foxi3a, which is expressed in a subset of the grhl1 population, caused a loss of ionocytes and a corresponding increase in the number of pvalb8-expressing cells, while leaving the number of grhl1-positive cells unaltered. We propose that grhl1 is a novel common marker of all or most “non-keratinocyte” epidermal progenitors, and that the sub-functionalisation of these cells is regulated by differential positive and negative effects of Foxi3 factors. PMID:19757382

Eradication of damaged keratinocytes in cutaneous lichen planus forms demonstrated by evaluation of epidermal and follicular expression of CK15, indices of apoptosis and regulatory protein S100.

PubMed

Upeniece, Ilze; Groma, Valerie; Skuja, Sandra; Cauce, Vinita

The study of cytoskeleton arrangement and its contribution to survival of cell-to-cell contacts appears to be essential for understanding of numerous cellular and tissue processes. Applying CK15, S100 labeling and TUNEL reaction to cutaneous lichen planus subtypes, we found CK15 expression in the outer and inner root sheath of hair follicles, the basal epidermal layer, and eccrine glands. Its follicular expression was decreased in nearby inflammatory infiltrates. The CK15 immunopositivity was mostly described as weak (92.3%) for lichen planus but equally subdivided into weak, moderate and strong in lichen planopilaris (2 = 32.514; df = 4; p < 0.001). The greatly varying apoptotic index was the highest in the lichen planopilaris involving the scalp: 81.2 ±10.7; 87.8 ±10.7 and 88.0 ±10.5 for the basal, spinous and upper epidermal layers, respectively. S100 positive epidermal and follicular cells did not differ in the lesions demonstrated in the study groups; still immunoreactivity was more pronounced in the scalp region of lichen planopilaris. Damage of cell-to-cell contacts was confirmed by electron microscopy. Apart from immunocyte-mediated keratinocyte death, cytoskeleton-based injury and loss of cell-to-cell and matrix contacts may be of great importance, leading to eradication of degrading cells and thus contributing to the pathogenesis of lichen planus.

Combined inhibition of EMMPRIN and epidermal growth factor receptor prevents the growth and migration of head and neck squamous cell carcinoma cells.

PubMed

Suzuki, Shinsuke; Ishikawa, Kazuo

2014-03-01

It has been reported that the epidermal growth factor receptor (EGFR) expression is associated with the extracellular matrix metalloproteinase inducer (EMMPRIN) in some solid tumors; however, the relationship of EMMPRIN with EGFR in head and neck cancers is not fully understood. To determine the relationship between EMMPRIN and EGFR in head and neck squamous cell carcinoma (HNSCC), HNSCC cells were stimulated with epidermal growth factor (EGF), a ligand of EGFR. EMMPRIN expression in HNSCC cells was upregulated by EGF. In addition, EGF stimulation induced HNSCC cell invasion and MMP-9 expression. This increase in invasion and MMP-9 expression was abrogated by downmodulation of EMMPRIN. Furthermore, to determine the effects of combined EMMPRIN and EGFR targeting in HNSCC, HNSCC cells were treated with an EMMPRIN function-blocking antibody and the EGFR inhibitor AG1478. This combined treatment resulted in greater inhibition of HNSCC cell proliferation and migration compared with the individual agents alone. These results suggest that EMMPRIN mediates EGFR-induced tumorigenicity and that combined targeting of EMMPRIN and EGFR may be an efficacious treatment approach.

Unilateral reorientation of microtubules at the outer epidermal wall during photo- and gravitropic curvature of maize coleoptiles and sunflower hypocotyls.

PubMed

Nick, P; Bergfeld, R; Schafer, E; Schopfer, P

1990-05-01

Auxin (indole-3-acetic acid) controls the orientation of cortical microtubes (MT) at the outer wall of the outer epidermis of growing maize coleoptiles (Bergfeld, R., Speth, V., Schopfer, P., 1988, Bot. Acta 101, 57-67). A detailed time course of MT reorientation, determined by labeling MT with fluorescent antibodies, revealed that the auxin-mediated movement of MT from the longitudinal to the transverse direction starts after less than 15 min and is completed after 60 min. This response was used for a critical test of the functional involvement of auxin in tropic curvature. It was found that phototropic (first phototropic curvature) as well as gravitropic bending are correlated with a change of MT orientation from transverse to longitudinal at the slower-growing organ flank whereas the transverse MT orientation is maintained (or even augmented) at the faster-growing organ flank. These directional changes are confined to the MT subjacent to the outer epidermal wall. The same basic results were obtained with sunflower hypocotyls subjected to phototropic or gravitropic stimulation. It is concluded that auxin is, in fact, involved in asymmetric growth leading to tropic curvature. However, our results do not allow us to discriminate between an uneven distribution of endogenous auxin or an even distribution of auxin, the activity of which is modulated by an unevenly distributed inhibitor of auxin action.

Reduced growth factor requirement of keloid-derived fibroblasts may account for tumor growth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russell, S.B.; Trupin, K.M.; Rodriguez-Eaton, S.

Keloids are benign dermal tumors that form during an abnormal wound-healing process is genetically susceptible individuals. Although growth of normal and keloid cells did not differ in medium containing 10% (vol/vol) fetal bovine serum, keloid culture grew to significantly higher densities than normal cells in medium containing 5% (vol/vol) fetal bovine serum, keloid cultures grew to significantly higher densities than normal cells in medium containing 5% (vol/vol) plasma or 1% fetal bovine serum. Conditioned medium from keloid cultures did not stimulate growth of normal cells in plasma nor did it contain detectable platelet-derived growth factor or epidermal growth factor. Keloidmore » fibroblasts responded differently than normal adult fibroblasts to transforming growth factor ..beta... Whereas transforming growth factor ..beta.. reduced growth stimulation by epidermal growth factor in cells from normal adult skin or scars, it enhanced the activity of epidermal growth factor in cells from normal adult skin or scars, it enhanced the activity of epidermal growth factor in cells from keloids. Normal and keloid fibroblasts also responded differently to hydrocortisone: growth was stimulated in normal adult cells and unaffected or inhibited in keloid cells. Fetal fibroblasts resembled keloid cells in their ability to grow in plasma and in their response to hydrocortisone. The ability of keloid fibroblasts to grow to higher cell densities in low-serum medium than cells from normal adult skin or from normal early or mature scars suggests that a reduced dependence on serum growth factors may account for their prolonged growth in vivo. Similarities between keloid and fetal cells suggest that keloids may result from the untimely expression of growth-control mechanism that is developmentally regulated.« less

Isolation and functional assessment of cutaneous stem cells.

PubMed

Doucet, Yanne S; Owens, David M

2015-01-01

The epidermis and associated appendages of the skin represent a multi-lineage tissue that is maintained by perpetual rounds of renewal. During homeostasis, turnover of epidermal lineages is achieved by input from regionalized keratinocytes stem or progenitor populations with little overlap from neighboring niches. Over the last decade, molecular markers selectively expressed by a number of these stem or progenitor pools have been identified, allowing for the isolation and functional assessment of stem cells and genetic lineage tracing analysis within intact skin. These advancements have led to many fundamental observations about epidermal stem cell function such as the identification of their progeny, their role in maintenance of skin homeostasis, or their contribution to wound healing. In this chapter, we provide a methodology to identify and isolate epidermal stem cells and to assess their functional role in their respective niche. Furthermore, recent evidence has shown that the microenvironment also plays a crucial role in stem cell function. Indeed, epidermal cells are under the influence of surrounding fibroblasts, adipocytes, and sensory neurons that provide extrinsic signals and mechanical cues to the niche and contribute to skin morphogenesis and homeostasis. A better understanding of these microenvironmental cues will help engineer in vitro experimental models with more relevance to in vivo skin biology. New approaches to address and study these environmental cues in vitro will also be addressed.

Intraepidermal but not dermal T lymphocytes are positive for a cell-cycle-associated antigen (Ki-67) in mycosis fungoides.

PubMed Central

Nickoloff, B. J.; Griffiths, C. E.

1990-01-01

The Ki-67 antibody, which reacts with nuclei of actively proliferating cells, was used in an immunohistochemical study to determine if there was any difference between T cells located in the epidermis rather than the dermis, in mycosis fungoides. In 12 of 14 cases of patch/plaque stage mycosis fungoides, the epidermal T cells were Ki-67 positive, while the dermal T cells were Ki-67 negative in all cases. Both epidermal and dermal T cells belonged primarily to the memory-versus-naive subset. The intraepidermal Ki-67-positive T cells were slightly larger than the dermal Ki-67-negative cells and could be easily distinguished from occasional basal keratinocytes that were also Ki-67 positive. We conclude that dermal T cells, despite expressing HLA-DR and a memory phenotype, are essentially in a resting (Go or noncycling state) in mycosis fungoides. Furthermore, it appears that the movement of T cells into the epidermal compartment is associated with activation and entry into the cell cycle. Such intraepidermal activation may lead to lymphokine release, and play an important pathophysiologic role in mycosis fungoides. Images Figure 1 Figure 5 PMID:1968314

Anti-proliferative effect of 20-hydroxyecdysone in a lepidopteran cell line.

PubMed

Auzoux-Bordenave, Stéphanie; Hatt, Philippe-Jacques; Porcheron, Patrick

2002-02-01

Ecdysteroids are steroid hormones involved in the epidermal growth of arthropods, controlling cell proliferation and further differentiation of target cells. The epidermal cell line IAL-PID2, established from imaginal discs of the Indian meal moth Plodia interpunctella kept its sensitivity to ecdysteroids in vitro, cells being able to respond to them by cytological and biochemical changes. When added to the culture medium, 20-hydroxyecdysone (20E) stopped cell proliferation and induced formation of epithelial-like aggregates. In order to better understand the cellular sequence of ecdysteroids signalling in epidermal cells we used the IAL-PID2 cell line for in vitro investigations of cytological events induced by the moulting hormone. After a 40 h serum deprivation, formazan assay (XTT) was routinely used to evaluate anti-proliferative effects of 20E during cell cycle. We established a more precise timing of the period of cell sensitivity to the hormone during the cell cycle, by the use of the mitotic index and the BrdU incorporation test. These in vitro assays were performed in parallel with the description of some hormone dependant cytological events, using immunofluorescent labelling with anti-beta tubulin/FITC antibodies and DNA staining.

Epidermal Viral Immunity Induced by CD8α+ Dendritic Cells But Not by Langerhans Cells

NASA Astrophysics Data System (ADS)

Allan, Rhys S.; Smith, Chris M.; Belz, Gabrielle T.; van Lint, Allison L.; Wakim, Linda M.; Heath, William R.; Carbone, Francis R.

2003-09-01

The classical paradigm for dendritic cell function derives from the study of Langerhans cells, which predominate within skin epidermis. After an encounter with foreign agents, Langerhans cells are thought to migrate to draining lymph nodes, where they initiate T cell priming. Contrary to this, we show here that infection of murine epidermis by herpes simplex virus did not result in the priming of virus-specific cytotoxic T lymphocytes by Langerhans cells. Rather, the priming response required a distinct CD8α+ dendritic cell subset. Thus, the traditional view of Langerhans cells in epidermal immunity needs to be revisited to accommodate a requirement for other dendritic cells in this response.

Multi-walled carbon nanotubes applied through seed-priming influence early germination, root hair, growth and yield of bread wheat (Triticum aestivum L.).

PubMed

Joshi, Anjali; Kaur, Simranjeet; Dharamvir, Keya; Nayyar, Harsh; Verma, Gaurav

2018-06-01

Reports of multi-walled carbon nanotubes (MWCNTs) incorporated into plants have indicated better yield and productivity, yet the phenomena need in-depth understanding especially when agricultural crops are tested. We primed wheat seeds with MWCNTs to understand the effects on germination, growth, anatomy, physiology and yield. This study, carried out in field conditions, is a step forward over the previous reports. Early germination, excessive root hair, denser stomata and larger root length result in faster growth and higher yield of wheat plants. Denser root hair facilitated the uptake of both water and essential minerals such as phosphorus (P) and potassium (K), which boosted the crop yield by significantly improving grain yield per plant from 1.53 to 2.5 g, a 63% increase. Increase in cell elongation by 80% was recorded, while xylem and phloem sizes dilated to almost 83% and 85% of control, thus enhancing their capacity to conduct water and nutrients. Augmented growth of MWCNT-primed wheat, enhancement in grain number, biomass, stomatal density, xylem-phloem size, epidermal cells, and water uptake is observed while finding no DNA damage. This opens up an entirely new aspect to using cost-effective nanomaterials (the MWCNTs were produced in-house) for enhancing the performance of crop plants. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

The presence of cutan limits the interpretation of cuticular chemistry and structure: Ficus elastica leaf as an example.

PubMed

Guzmán-Delgado, Paula; Graça, José; Cabral, Vanessa; Gil, Luis; Fernández, Victoria

2016-06-01

Plant cuticles have been traditionally classified on the basis of their ultrastructure, with certain chemical composition assumptions. However, the nature of the plant cuticle may be misinterpreted in the prevailing model, which was established more than 150 years ago. Using the adaxial leaf cuticle of Ficus elastica, a study was conducted with the aim of analyzing cuticular ultrastructure, chemical composition and the potential relationship between structure and chemistry. Gradual chemical extractions and diverse analytical and microscopic techniques were performed on isolated leaf cuticles of two different stages of development (i.e. young and mature leaves). Evidence for the presence of cutan in F. elastica leaf cuticles has been gained after chemical treatments and tissue analysis by infrared spectroscopy and electron microscopy. Significant calcium, boron and silicon concentrations were also measured in the cuticle of this species. Such mineral elements which are often found in plant cell walls may play a structural role and their presence in isolated cuticles further supports the interpretation of the cuticle as the most external region of the epidermal cell wall. The complex and heterogeneous nature of the cuticle, and constraints associated with current analytical procedures may limit the chance for establishing a relationship between cuticle chemical composition and structure also in relation to organ ontogeny. © 2016 Scandinavian Plant Physiology Society.

Regulators of floral fragrance production and their target genes in petunia are not exclusively active in the epidermal cells of petals

PubMed Central

Van Moerkercke, Alex; Galván-Ampudia, Carlos S.; Verdonk, Julian C.; Haring, Michel A.; Schuurink, Robert C.

2012-01-01

In which cells of the flower volatile biosynthesis takes place is unclear. In rose and snapdragon, some enzymes of the volatile phenylpropanoid/benzenoid pathway have been shown to be present in the epidermal cells of petals. It is therefore generally believed that the production of these compounds occurs in these cells. However, whether the entire pathway is active in these cells and whether it is exclusively active in these cells remains to be proven. Cell-specific transcription factors activating these genes will determine in which cells they are expressed. In petunia, the transcription factor EMISSION OF BENZENOIDS II (EOBII) activates the ODORANT1 (ODO1) promoter and the promoter of the biosynthetic gene isoeugenol synthase (IGS). The regulator ODO1 in turn activates the promoter of the shikimate gene 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). Here the identification of a new target gene of ODO1, encoding an ABC transporter localized on the plasma membrane, PhABCG1, which is co-expressed with ODO1, is described. PhABCG1 expression is up-regulated in petals overexpressing ODO1 through activation of the PhABCG1 promoter. Interestingly, the ODO1, PhABCG1, and IGS promoters were active in petunia protoplasts originating from both epidermal and mesophyll cell layers of the petal, suggesting that the volatile phenylpropanoid/benzenoid pathway in petunia is active in these different cell types. Since volatile release occurs from epidermal cells, trafficking of (volatile) compounds between cell layers must be involved, but the exact function of PhABCG1 remains to be resolved. PMID:22345641

“String of pearls pattern”: report of three cases of non clear-cell acanthoma*

PubMed Central

Espinosa, Ana Elena Domínguez; Akay, Bengu Nisa; González-Ramírez, Roger Adrian

2017-01-01

The coiled and dotted vessels in a serpiginous arrangement or “string of pearls” is considered a classical vascular pattern associated with clear cell acanthoma. We present three cases of epidermal tumors different from clear cell acanthoma that have the same “string of pearls” vascular pattern. Even though most authors keep considering the “string of pearls” vascular pattern an almost pathognomonic sign of clear-cell acanthoma, the cases presented here suggest that some other epidermal tumors can also show this pattern. PMID:29267474

dsRNA silencing of an R2R3-MYB transcription factor affects flower cell shape in a Dendrobium hybrid.

PubMed

Lau, Su-Ee; Schwarzacher, Trude; Othman, Rofina Yasmin; Harikrishna, Jennifer Ann

2015-08-11

The R2R3-MYB genes regulate pigmentation and morphogenesis of flowers, including flower and cell shape, and therefore have importance in the development of new varieties of orchids. However, new variety development is limited by the long breeding time required in orchids. In this study, we identified a cDNA, DhMYB1, that is expressed during flower development in a hybrid orchid, Dendrobium hybrida (Dendrobium bobby messina X Dendrobium chao phraya) then used the direct application of dsRNA to observe the effect of gene silencing on flower phenotype and floral epidermal cell shape. Flower bud development in the Dendrobium hybrid was characterised into seven stages and the time of meiosis was determined as between stages 3 to 5 when the bud is approximately half of the mature size. Scanning electron microscopy characterisation of adaxial epidermal cells of the flower perianth, showed that the petals and sepals each are divided into two distinct domains based on cell shape and size, while the labellum comprises seven domains. Thirty-two partial cDNA fragments representing R2R3-MYB gene sequences were isolated from D. hybrida. Phylogenetic analysis revealed that nine of the translated sequences were clustered with MYB sequences that are known to be involved in cell shape development and from these, DhMYB1 was selected for full length cDNA cloning and functional study. Direct application of a 430 bp dsRNA from the 3' region of DhMYB1 to emerging orchid flower buds reduced expression of DhMYB1 RNA compared with untreated control. Scanning electron microscopy of adaxial epidermal cells within domain one of the labellum of flowers treated with DhMYB1 dsRNA showed flattened epidermal cells whilst those of control flowers were conical. DhMYB1 is expressed throughout flower bud development and is involved in the development of the conical cell shape of the epidermal cells of the Dendrobium hybrida flower labellum. The direct application of dsRNA changed the phenotype of floral cells, thus, this technique may have application in floriculture biotechnology.

Epidermal 'alarm substance' cells of fishes maintained by non-alarm functions: possible defence against pathogens, parasites and UVB radiation.

PubMed

Chivers, Douglas P; Wisenden, Brian D; Hindman, Carrie J; Michalak, Tracy A; Kusch, Robin C; Kaminskyj, Susan G W; Jack, Kristin L; Ferrari, Maud C O; Pollock, Robyn J; Halbgewachs, Colin F; Pollock, Michael S; Alemadi, Shireen; James, Clayton T; Savaloja, Rachel K; Goater, Cameron P; Corwin, Amber; Mirza, Reehan S; Kiesecker, Joseph M; Brown, Grant E; Adrian, James C; Krone, Patrick H; Blaustein, Andrew R; Mathis, Alicia

2007-10-22

Many fishes possess specialized epidermal cells that are ruptured by the teeth of predators, thus reliably indicating the presence of an actively foraging predator. Understanding the evolution of these cells has intrigued evolutionary ecologists because the release of these alarm chemicals is not voluntary. Here, we show that predation pressure does not influence alarm cell production in fishes. Alarm cell production is stimulated by exposure to skin-penetrating pathogens (water moulds: Saprolegnia ferax and Saprolegnia parasitica), skin-penetrating parasites (larval trematodes: Teleorchis sp. and Uvulifer sp.) and correlated with exposure to UV radiation. Suppression of the immune system with environmentally relevant levels of Cd inhibits alarm cell production of fishes challenged with Saprolegnia. These data are the first evidence that alarm substance cells have an immune function against ubiquitous environmental challenges to epidermal integrity. Our results indicate that these specialized cells arose and are maintained by natural selection owing to selfish benefits unrelated to predator-prey interactions. Cell contents released when these cells are damaged in predator attacks have secondarily acquired an ecological role as alarm cues because selection favours receivers to detect and respond adaptively to public information about predation.

Fractalkine receptor is expressed in mature ovarian teratomas and required for epidermal lineage differentiation

PubMed Central

2013-01-01

Background The goal of this study was to determine a predominant cell type expressing fractalkine receptor (CX3CR1) in mature ovarian teratomas and to establish functional significance of its expression in cell differentiation. Methods Specimens of ovarian teratoma and human fetal tissues were analyzed by immunohistochemistry for CX3CR1expression. Ovarian teratocarcinoma cell line PA-1 was used as a model for cell differentiation. Results We found that the majority of the specimens contained CX3CR1-positive cells of epidermal lineage. Skin keratinocytes in fetal tissues were also CX3CR1- positive. PA-1 cells with downregulated CX3CR1 failed to express a skin keratinocyte marker cytokeratin 14 when cultured on Matrigel in the presence of a morphogen, bone morphogenic protein 4 (BMP-4), as compared to those expressing scrambled shRNA. Conclusions Here we demonstrate that CX3CR1 is expressed in both normally (fetal skin) and abnormally (ovarian teratoma) differentiated keratinocytes and is required for cell differentiation into epidermal lineage. PMID:23958497

Genetic Correction of Stem Cells in the Treatment of Inherited Diseases and Focus on Xeroderma Pigmentosum

PubMed Central

Rouanet, Sophie; Warrick, Emilie; Gache, Yannick; Scarzello, Sabine; Avril, Marie-Françoise; Bernerd, Françoise; Magnaldo, Thierry

2013-01-01

Somatic stem cells ensure tissue renewal along life and healing of injuries. Their safe isolation, genetic manipulation ex vivo and reinfusion in patients suffering from life threatening immune deficiencies (for example, severe combined immunodeficiency (SCID)) have demonstrated the efficacy of ex vivo gene therapy. Similarly, adult epidermal stem cells have the capacity to renew epidermis, the fully differentiated, protective envelope of our body. Stable skin replacement of severely burned patients have proven life saving. Xeroderma pigmentosum (XP) is a devastating disease due to severe defects in the repair of mutagenic DNA lesions introduced upon exposure to solar radiations. Most patients die from the consequences of budding hundreds of skin cancers in the absence of photoprotection. We have developed a safe procedure of genetic correction of epidermal stem cells isolated from XP patients. Preclinical and safety assessments indicate successful correction of XP epidermal stem cells in the long term and their capacity to regenerate a normal skin with full capacities of DNA repair. PMID:24113582

Integrin Beta 1 Suppresses Multilayering of a Simple Epithelium

PubMed Central

Chen, Jichao; Krasnow, Mark A.

2012-01-01

Epithelia are classified as either simple, a single cell layer thick, or stratified (multilayered). Stratified epithelia arise from simple epithelia during development, and transcription factor p63 functions as a key positive regulator of epidermal stratification. Here we show that deletion of integrin beta 1 (Itgb1) in the developing mouse airway epithelium abrogates airway branching and converts this monolayer epithelium into a multilayer epithelium with more than 10 extra layers. Mutant lung epithelial cells change mitotic spindle orientation to seed outer layers, and cells in different layers become molecularly and functionally distinct, hallmarks of normal stratification. However, mutant lung epithelial cells do not activate p63 and do not switch to the stratified keratin profile of epidermal cells. These data, together with previous data implicating Itgb1 in regulation of epidermal stratification, suggest that the simple-versus-stratified developmental decision may involve not only stratification inducers like p63 but suppressors like Itgb1 that prevent simple epithelia from inappropriately activating key steps in the stratification program. PMID:23285215

Cellular interactions of a lipid-based nanocarrier model with human keratinocytes: Unravelling transport mechanisms.

PubMed

Silva, Elisabete; Barreiros, Luísa; Segundo, Marcela A; Costa Lima, Sofia A; Reis, Salette

2017-04-15

Knowledge of delivery system transport through epidermal cell monolayer is vital to improve skin permeation and bioavailability. Recently, nanostructured lipid carriers (NLCs) have gained great attention for transdermal delivery due to their biocompatibility, high drug payload, occlusive properties and skin hydration effect. However, the nanocarriers transport related mechanisms in epidermal epithelial cells are not yet understood. In this research, the internalization and transport pathways of the NLCs across the epidermal epithelial cell monolayer (HaCaT cells) were investigated. The 250nm sized witepsol/miglyol NLCs, prepared by hot homogenization had reduced cytotoxicity and no effect on the integrity of cell membrane in human HaCaT keratinocytes. The internalization was time-, concentration- and energy-dependent, and the uptake of NLCs was a vesicle-mediated process by macropinocytosis and clathrin-mediated pathways. 3% of NLCs were found at the apical membrane side of the HaCaT monolayer through exocytosis mechanism. Additionally, the endoplasmic reticulum, Golgi apparatus and microtubules played crucial roles in the transport of NLCs out of HaCaT cells. NLCs were transported intact across the human keratinocytes monolayer, without disturbing the tight junction's structure. From the transcytosis data only approximately 12% of the internalized NLCs were passed from the apical to the basolateral side. The transcytosis of NLCs throughout the HaCaT cell monolayer towards the basolateral membrane side requires the involvement of the endoplasmic reticulum, Golgi apparatus and microtubules. Our findings may contribute to a systematic understanding of NLCs transport across epidermal epithelial cell monolayers and their optimization for clinical transdermal application. Transdermal drug delivery is a challenging and growing area of clinical application. Lipid nanoparticles such as nanostructured lipid carriers (NLCs) have gained wide interest for transdermal drug delivery. However these nanocarriers' interactions with epidermal epithelial barrier are yet unknown. Unveiling the mechanisms involved in NLCs transport across the epidermal epithelial monolayers will contribute with valuable information to achieve enhanced skin permeability, superior bioavailability and consequently improved therapeutic effect. With our present work we could certainly provide researchers and clinicians guidance for the design of optimized transdermal delivery systems, based on the nanomaterials and biological interactions. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Erlotinib induced target-like purpura.

PubMed

Rungtrakulchai, R; Rerknimitr, P

2014-02-18

Erlotinib is an epidermal growth factor receptor (EGFR) inhibitor, used as a treatment for advanced stage cancer. The most common side effect is cutaneous toxicity including the already known papulopustular reaction. We herein report a case of erlotinib induced target-like purpura, a peculiar cutaneous adverse event. A 57-year-old patient with advanced non-small cell lung cancer was treated by erolotinib 150 mg daily. After taking the drug for three days, an unusual target-like purpura developed on her lower legs. Skin biopsy specimen taken from the lesion revealed an extravasation of erythrocytes in the upper dermis without destruction of blood vessel walls. This skin eruption cleared after the drug was withdrawn and recurred after erlotinib was re-challenged. The mechanism underlying this cutaneous adverse event remains to be elucidated. Physicians should be aware of the rare side effect of this increasingly used drug.

Expression and analysis of exogenous proteins in epidermal cells.

PubMed

Dagnino, Lina; Ho, Ernest; Chang, Wing Y

2010-01-01

In this chapter we review protocols for transient transfection of primary keratinocytes. The ability to transfect primary epidermal cells regardless of their differentiation status allows the biochemical and molecular characterization of multiple proteins. We review methods to analyze exogenous protein abundance in transfected keratinocytes by immunoblot and immunoprecipitation. We also present protocols to determine the subcellular distribution of these proteins by indirect immunofluorescence microscopy approaches.

Increase in epidermal planar cell density accompanies decreased russeting of “Golden Delicious” apples treated with gibberellin A4+7

USDA-ARS?s Scientific Manuscript database

A two-year study was conducted in a “Golden Delicious” (Malus Xdomestica Borkh.) orchard having a high historical incidence of physiological fruit russeting, to examine the effect of gibberellin A4+7 (GA4+7) on apple epidermal cell size. Beginning at petal fall, four sequential applications of GA4+7...

Combination of Vessel-Targeting Agents and Fractionated Radiation Therapy: The Role of the SDF-1/CXCR4 Pathway

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Fang-Hsin; Fu, Sheng-Yung; Yang, Ying-Chieh

2013-07-15

Purpose: To investigate vascular responses during fractionated radiation therapy (F-RT) and the effects of targeting pericytes or bone marrow-derived cells (BMDCs) on the efficacy of F-RT. Methods and Materials: Murine prostate TRAMP-C1 tumors were grown in control mice or mice transplanted with green fluorescent protein-tagged bone marrow (GFP-BM), and irradiated with 60 Gy in 15 fractions. Mice were also treated with gefitinib (an epidermal growth factor receptor inhibitor) or AMD3100 (a CXCR4 antagonist) to examine the effects of combination treatment. The responses of tumor vasculatures to these treatments and changes of tumor microenvironment were assessed. Results: After F-RT, the tumormore » microvascular density (MVD) was reduced; however, the surviving vessels were dilated, incorporated with GFP-positive cells, tightly adhered to pericytes, and well perfused with Hoechst 33342, suggesting a more mature structure formed primarily via vasculogenesis. Although the gefitinib+F-RT combination affected the vascular structure by dissociating pericytes from the vascular wall, it did not further delay tumor growth. These tumors had higher MVD and better vascular perfusion function, leading to less hypoxia and tumor necrosis. By contrast, the AMD3100+F-RT combination significantly enhanced tumor growth delay more than F-RT alone, and these tumors had lower MVD and poorer vascular perfusion function, resulting in increased hypoxia. These tumor vessels were rarely covered by pericytes and free of GFP-positive cells. Conclusions: Vasculogenesis is a major mechanism for tumor vessel survival during F-RT. Complex interactions occur between vessel-targeting agents and F-RT, and a synergistic effect may not always exist. To enhance F-RT, using CXCR4 inhibitor to block BM cell influx and the vasculogenesis process is a better strategy than targeting pericytes by epidermal growth factor receptor inhibitor.« less

Glucose transporter member 1 is involved in UVB-induced epidermal hyperplasia by enhancing proliferation in epidermal keratinocytes.

PubMed

Tochio, Takumi; Tanaka, Hiroshi; Nakata, Satoru

2013-03-01

Glucose transporter member 1 (GLUT-1) is one of the major facilitated glucose transporters and contributes to the promotion of keratinocyte proliferation in psoriasis and carcinogenic lesions. In this study, we postulate that GLUT-1 is involved in ultraviolet B (UVB)-induced epidermal hyperplasia. The purpose of this study is to investigate the possible role of GLUT-1 in UVB-induced hyperplasia. The effects of UVB on GLUT-1 expression levels were investigated in in vitro and in vivo studies. In addition, the involvement of epidermal growth factor (EGF) and hypoxia inducible factor-1 alpha (HIF-1α), transcriptional factors for GLUT-1, in GLUT-1-related events were investigated. GLUT-1 mRNA and its protein levels were markedly increased by UVB irradiation in HaCaT cells. In in vivo studies, a strong immunofluorescence signal of GLUT-1 was clearly observed around the basal layer of the epidermis, which proliferated excessively by UVB irradiation. In HaCaT cells, EGF mRNA and its protein levels were markedly increased by UVB irradiation, and then the GLUT-1 mRNA level was significantly increased by treatment with EGF. Additionally, the upregulation of GLUT-1 by both UVB irradiation and treatment with EGF was significantly suppressed by transfection with HIF-1α siRNA. We conclude that GLUT-1 is involved in UVB-induced epidermal hyperplasia by enhancing proliferation of epidermal basal cells, and the GLUT-1-related event might be regulated by an increase in HIF-1α stimulated by EGF. © 2013 The International Society of Dermatology.

Combination therapy of potential gene to enhance oral cancer therapeutic effect

NASA Astrophysics Data System (ADS)

Yeh, Chia-Hsien; Hsu, Yih-Chih

2015-03-01

The epidermal growth factor receptor (EGFR) over-regulation related to uncontrolled cell division and promotes progression in tumor. Over-expression of human epidermal growth factor receptor (EGFR) has been detected in oral cancer cells. EGFR-targeting agents are potential therapeutic modalities for treating oral cancer based on our in vitro study. Liposome nanotechnology is used to encapsulate siRNA and were modified with target ligand to receptors on the surface of tumor cells. We used EGFR siRNA to treat oral cancer in vitro.

A case of epidermal cyst with pilomatrical differentiation.

PubMed

Ikoma, Norihiro; Iwashita, Kenichi; Umezawa, Yoshinori; Matsuyama, Takashi; Ohta, Yukinori; Ozawa, Akira; Umemura, Shinobu; Ueyama, Yoshito; Yamazaki, Hitoshi

2004-09-01

A 20-year-old Japanese woman with an epidermal cyst on the back is described. Physical examination revealed a deep blue and round shaped cystic lesion measuring 10 min in diameter. A comedo-like keratotic plug also could be seen at the center. Histologically, the inner surface of the cyst was clearly separated of two types of the cells. The one was layers of epidermal keratinocytes and the other looked like a basal layer of epidermis, which immunohistochemically stained by S-100, HMB-45, cytokeratin (CK19) and Fontana-Masson staining. We diagnosed this case as epidermal cyst with pilomatrical differentiation.

Effects of Telomerase and Telomere Length on Epidermal Stem Cell Behavior

NASA Astrophysics Data System (ADS)

Flores, Ignacio; Cayuela, María L.; Blasco, María A.

2005-08-01

A key process in organ homeostasis is the mobilization of stem cells out of their niches. We show through analysis of mouse models that telomere length, as well as the catalytic component of telomerase, Tert, are critical determinants in the mobilization of epidermal stem cells. Telomere shortening inhibited mobilization of stem cells out of their niche, impaired hair growth, and resulted in suppression of stem cell proliferative capacity in vitro. In contrast, Tert overexpression in the absence of changes in telomere length promoted stem cell mobilization, hair growth, and stem cell proliferation in vitro. The effects of telomeres and telomerase on stem cell biology anticipate their role in cancer and aging.

Isolation, Culture, and Motility Measurements of Epidermal Melanocytes from GFP-Expressing Reporter Mice.

PubMed

Dagnino, Lina; Crawford, Melissa

2018-03-27

In this article, we provide a method to isolate primary epidermal melanocytes from reporter mice, which also allow targeted gene inactivation. The mice from which these cells are isolated are bred into a Rosa26 mT/mG reporter background, which results in GFP expression in the targeted melanocytic cell population. These cells are isolated and cultured to >95% purity. The cells can be used for gene expression studies, clonogenic experiments, and biological assays, such as capacity for migration. Melanocytes are slow moving cells, and we also provide a method to measure motility using individual cell tracking and data analysis.

Human epidermal langerhans cells express the immunoregulatory enzyme indoleamine 2,3-dioxygenase.

PubMed

von Bubnoff, Dagmar; Bausinger, Huguette; Matz, Heike; Koch, Susanne; Häcker, Georg; Takikawa, Osamu; Bieber, Thomas; Hanau, Daniel; de la Salle, Henri

2004-08-01

Langerhans cells (LC) are a special subset of dendritic cells integrating cutaneous immunity. The study of LC function is of major interest not only for efforts of vaccine design and immunotherapy but also for gaining an insight into the pathogenesis of immune-mediated cutaneous diseases and neoplasias. Recently, defined antigen-presenting cells were described that express indoleamine 2,3-dioxygenase (IDO) and inhibit T cell proliferation in vitro and in vivo. Here, we show that stimulation with interferon-gamma (IFN-gamma) induces the expression of functionally active IDO in highly purified human epidermal LC. The induction of IDO after stimulation of LC with IFN-gamma seems to follow a defined kinetic with rapid upregulation followed by a downregulation after about 24 h of culture. Accordingly, proliferation of T cells induced by anti-CD3 antibodies was modulated by supernatants of IFN-gamma-activated human epidermal LC. Importantly, downregulation of T cell proliferation by supernatants of 24 h IFN-gamma-activated LC was prevented by inhibition of IDO. These results indicate that LC not only have the capacity to stimulate but also to inhibit T cells, and suggest that LC possess an immunoregulatory function in promoting T cell tolerance by production of IDO.

Althaea rosea Cavanil and Plantago major L. suppress neoplastic cell transformation through the inhibition of epidermal growth factor receptor kinase.

PubMed

Choi, Eun-Sun; Cho, Sung-Dae; Shin, Ji-Ae; Kwon, Ki Han; Cho, Nam-Pyo; Shim, Jung-Hyun

2012-10-01

For thousands of years in Asia, Althaea rosea Cavanil (ARC) and Plantago major L. (PML) have been used as powerful non-toxic therapeutic agents that inhibit inflammation. However, the anticancer mechanisms and molecular targets of ARC and PML are poorly understood, particularly in epidermal growth factor (EGF)-induced neoplastic cell transformation. The aim of this study was to evaluate the chemopreventive effects and mechanisms of the methanol extracts from ARC (MARC) and PML (MPML) in EGF-induced neoplastic cell transformation of JB6 P+ mouse epidermal cells using an MTS assay, anchorage-independent cell transformation assay and western blotting. Our results showed that MARC and MPML significantly suppressed neoplastic cell transformation by inhibiting the kinase activity of the EGF receptor (EGFR). The activation of EGFR by EGF was suppressed by MARC and MPML treatment in EGFR(+/+) cells, but not in EGFR(-/-) cells. In addition, MARC and MPML inhibited EGF-induced cell proliferation in EGFR-expressing murine embryonic fibroblasts (EGFR(+/+)). These results strongly indicate that EGFR targeting by MARC and MPML may be a good strategy for chemopreventive or chemotherapeutic applications.

Hair Follicle and Sebaceous Gland De Novo Regeneration With Cultured Epidermal Stem Cells and Skin-Derived Precursors.

PubMed

Wang, Xiaoxiao; Wang, Xusheng; Liu, Jianjun; Cai, Ting; Guo, Ling; Wang, Shujuan; Wang, Jinmei; Cao, Yanpei; Ge, Jianfeng; Jiang, Yuyang; Tredget, Edward E; Cao, Mengjun; Wu, Yaojiong

2016-12-01

: Stem cell-based organ regeneration is purported to enable the replacement of impaired organs in the foreseeable future. Here, we demonstrated that a combination of cultured epidermal stem cells (Epi-SCs) derived from the epidermis and skin-derived precursors (SKPs) was capable of reconstituting functional hair follicles and sebaceous glands (SG). When Epi-SCs and SKPs were mixed in a hydrogel and implanted into an excisional wound in nude mice, the Epi-SCs formed de novo epidermis along with hair follicles, and SKPs contributed to dermal papilla in the neogenic hair follicles. Notably, a combination of culture-expanded Epi-SCs and SKPs derived from the adult human scalp were sufficient to generate hair follicles and hair. Bone morphogenetic protein 4, but not Wnts, sustained the expression of alkaline phosphatase in SKPs in vitro and the hair follicle-inductive property in vivo when SKPs were engrafted with neonatal epidermal cells into excisional wounds. In addition, Epi-SCs were capable of differentiating into sebocytes and formed de novo SGs, which excreted lipids as do normal SGs. Thus our results indicate that cultured Epi-SCs and SKPs are sufficient to generate de novo hair follicles and SGs, implying great potential to develop novel bioengineered skin substitutes with appendage genesis capacity. In postpartum humans, skin appendages lost in injury are not regenerated, despite the considerable achievement made in skin bioengineering. In this study, transplantation of a combination of culture-expanded epidermal stem cells and skin-derived progenitors from mice and adult humans led to de novo regeneration of functional hair follicles and sebaceous glands. The data provide transferable knowledge for the development of novel bioengineered skin substitutes with epidermal appendage regeneration capacity. ©AlphaMed Press.

Pleiotropic Phenotypes of the sticky peel Mutant Provide New Insight into the Role of CUTIN DEFICIENT2 in Epidermal Cell Function in Tomato1[W][OA

PubMed Central

Nadakuduti, Satya Swathi; Pollard, Mike; Kosma, Dylan K.; Allen, Charles; Ohlrogge, John B.; Barry, Cornelius S.

2012-01-01

Plant epidermal cells have evolved specialist functions associated with adaptation to stress. These include the synthesis and deposition of specialized metabolites such as waxes and cutin together with flavonoids and anthocyanins, which have important roles in providing a barrier to water loss and protection against UV radiation, respectively. Characterization of the sticky peel (pe) mutant of tomato (Solanum lycopersicum) revealed several phenotypes indicative of a defect in epidermal cell function, including reduced anthocyanin accumulation, a lower density of glandular trichomes, and an associated reduction in trichome-derived terpenes. In addition, pe mutant fruit are glossy and peels have increased elasticity due to a severe reduction in cutin biosynthesis and altered wax deposition. Leaves of the pe mutant are also cutin deficient and the epicuticular waxes contain a lower proportion of long-chain alkanes. Direct measurements of transpiration, together with chlorophyll-leaching assays, indicate increased cuticular permeability of pe leaves. Genetic mapping revealed that the pe locus represents a new allele of CUTIN DEFICIENT2 (CD2), a member of the class IV homeodomain-leucine zipper gene family, previously only associated with cutin deficiency in tomato fruit. CD2 is preferentially expressed in epidermal cells of tomato stems and is a homolog of Arabidopsis (Arabidopsis thaliana) ANTHOCYANINLESS2 (ANL2). Analysis of cuticle composition in leaves of anl2 revealed that cutin accumulates to approximately 60% of the levels observed in wild-type Arabidopsis. Together, these data provide new insight into the role of CD2 and ANL2 in regulating diverse metabolic pathways and in particular, those associated with epidermal cells. PMID:22623518

Pleiotropic phenotypes of the sticky peel mutant provide new insight into the role of CUTIN DEFICIENT2 in epidermal cell function in tomato.

PubMed

Nadakuduti, Satya Swathi; Pollard, Mike; Kosma, Dylan K; Allen, Charles; Ohlrogge, John B; Barry, Cornelius S

2012-07-01

Plant epidermal cells have evolved specialist functions associated with adaptation to stress. These include the synthesis and deposition of specialized metabolites such as waxes and cutin together with flavonoids and anthocyanins, which have important roles in providing a barrier to water loss and protection against UV radiation, respectively. Characterization of the sticky peel (pe) mutant of tomato (Solanum lycopersicum) revealed several phenotypes indicative of a defect in epidermal cell function, including reduced anthocyanin accumulation, a lower density of glandular trichomes, and an associated reduction in trichome-derived terpenes. In addition, pe mutant fruit are glossy and peels have increased elasticity due to a severe reduction in cutin biosynthesis and altered wax deposition. Leaves of the pe mutant are also cutin deficient and the epicuticular waxes contain a lower proportion of long-chain alkanes. Direct measurements of transpiration, together with chlorophyll-leaching assays, indicate increased cuticular permeability of pe leaves. Genetic mapping revealed that the pe locus represents a new allele of CUTIN DEFICIENT2 (CD2), a member of the class IV homeodomain-leucine zipper gene family, previously only associated with cutin deficiency in tomato fruit. CD2 is preferentially expressed in epidermal cells of tomato stems and is a homolog of Arabidopsis (Arabidopsis thaliana) ANTHOCYANINLESS2 (ANL2). Analysis of cuticle composition in leaves of anl2 revealed that cutin accumulates to approximately 60% of the levels observed in wild-type Arabidopsis. Together, these data provide new insight into the role of CD2 and ANL2 in regulating diverse metabolic pathways and in particular, those associated with epidermal cells.

Hair Follicle and Sebaceous Gland De Novo Regeneration With Cultured Epidermal Stem Cells and Skin-Derived Precursors

PubMed Central

Wang, Xiaoxiao; Wang, Xusheng; Liu, Jianjun; Cai, Ting; Guo, Ling; Wang, Shujuan; Wang, Jinmei; Cao, Yanpei; Ge, Jianfeng; Jiang, Yuyang; Tredget, Edward E.; Cao, Mengjun

2016-01-01

Stem cell-based organ regeneration is purported to enable the replacement of impaired organs in the foreseeable future. Here, we demonstrated that a combination of cultured epidermal stem cells (Epi-SCs) derived from the epidermis and skin-derived precursors (SKPs) was capable of reconstituting functional hair follicles and sebaceous glands (SG). When Epi-SCs and SKPs were mixed in a hydrogel and implanted into an excisional wound in nude mice, the Epi-SCs formed de novo epidermis along with hair follicles, and SKPs contributed to dermal papilla in the neogenic hair follicles. Notably, a combination of culture-expanded Epi-SCs and SKPs derived from the adult human scalp were sufficient to generate hair follicles and hair. Bone morphogenetic protein 4, but not Wnts, sustained the expression of alkaline phosphatase in SKPs in vitro and the hair follicle-inductive property in vivo when SKPs were engrafted with neonatal epidermal cells into excisional wounds. In addition, Epi-SCs were capable of differentiating into sebocytes and formed de novo SGs, which excreted lipids as do normal SGs. Thus our results indicate that cultured Epi-SCs and SKPs are sufficient to generate de novo hair follicles and SGs, implying great potential to develop novel bioengineered skin substitutes with appendage genesis capacity. Significance In postpartum humans, skin appendages lost in injury are not regenerated, despite the considerable achievement made in skin bioengineering. In this study, transplantation of a combination of culture-expanded epidermal stem cells and skin-derived progenitors from mice and adult humans led to de novo regeneration of functional hair follicles and sebaceous glands. The data provide transferable knowledge for the development of novel bioengineered skin substitutes with epidermal appendage regeneration capacity. PMID:27458264

Autologous epidermal cells can induce wound closure of neurotrophic ulceration caused by trigeminal trophic syndrome.

PubMed

Schwerdtner, O; Damaskos, T; Kage, A; Weitzel-Kage, D; Klein, M

2005-06-01

Trigeminal trophic syndrome is an extremely rare complication following surgical ablation of the trigeminal nerve or after alcohol injection or thermocoagulation of the Gasserian ganglion. These lesions show a poor healing tendency and sometimes persist for years. The therapeutic results of local wound care with ointments and wound dressings are often unsatisfactory, and those of plastic surgery are variable. In the case presented, the skin area affected by neurotrophic ulceration is successfully treated with autologous cultivated epidermal cells. This form of tissue engineering is already a clinically established procedure for treating burns and chronic wounds. The results show for the first time that transplantation of in vitro cultivated epidermal cells can induce tissue regeneration and may be an effective tool in the treatment of neurotrophic ulcerations in the facial region.

Nocturnal Accumulation of Malic Acid Occurs in Mesophyll Tissue without Proton Transport to Epidermal Tissue in the Inducible Crassulacean Acid Metabolism Plant Mesembryanthemum crystallinum1

PubMed Central

Winter, Klaus; Edwards, Gerald E.; Holtum, Joseph A. M.

1981-01-01

The inducible Crassulacean acid metabolism plant, Mesembryanthemum crystallinum, accumulates malic acid, i.e. equivalent amounts of malate anions and protons in the mesophyll cells at night. Levels of malate and titratable acidity are low in the epidermal tissue and do not change significantly during the day/night cycle. This result is in contrast to a recent report (Bloom 1979 Plant Physiol 64: 919-923) that the synthesis of malic acid during dark CO2 fixation is associated with an equivalent exchange of inorganic cations from epidermal tissue with protons in the mesophyll cells. PMID:16661916

A Common Position-Dependent Mechanism Controls Cell-Type Patterning and GLABRA2 Regulation in the Root and Hypocotyl Epidermis of Arabidopsis1

PubMed Central

Hung, Chen-Yi; Lin, Yan; Zhang, Meng; Pollock, Susan; David Marks, M.; Schiefelbein, John

1998-01-01

A position-dependent pattern of epidermal cell types is produced during root development in Arabidopsis thaliana. This pattern is reflected in the expression pattern of GLABRA2 (GL2), a homeobox gene that regulates cell differentiation in the root epidermis. GL2 promoter::GUS fusions were used to show that the TTG gene, a regulator of root epidermis development, is necessary for maximal GL2 activity but is not required for the pattern of GL2 expression. Furthermore, GL2-promoter activity is influenced by expression of the myc-like maize R gene (35S::R) in Arabidopsis but is not affected by gl2 mutations. A position-dependent pattern of cell differentiation and GL2-promoter activity was also discovered in the hypocotyl epidermis that was analogous to the pattern in the root. Non-GL2-expressing cell files in the hypocotyl epidermis located outside anticlinal cortical cell walls exhibit reduced cell length and form stomata. Like the root, the hypocotyl GL2 activity was shown to be influenced by ttg and 35S::R but not by gl2. The parallel pattern of cell differentiation in the root and hypocotyl indicates that TTG and GL2 participate in a common position-dependent mechanism to control cell-type patterning throughout the apical-basal axis of the Arabidopsis seedling. PMID:9576776

Combination cisplatin and sulforaphane treatment reduces proliferation, invasion, and tumor formation in epidermal squamous cell carcinoma.

PubMed

Kerr, Candace; Adhikary, Gautam; Grun, Daniel; George, Nicholas; Eckert, Richard L

2018-01-01

Epidermal squamous cell carcinoma is an extremely common type of cancer. Early tumors can be successfully treated by surgery, but recurrent disease is aggressive and resistant to therapy. Cisplatin is often used as a treatment, but the outcome is rarely satisfactory. For this reason new strategies are required. Sulforaphane is a diet-derived cancer prevention agent that is effective in suppressing tumor growth in animal models of skin cancer. We monitored the efficacy of sulforaphane and cisplatin as a combined therapy for squamous cell carcinoma. Both agents suppress cell proliferation, growth of cancer stem cell spheroids, matrigel invasion and migration of SCC-13 and HaCaT cells, and combination treatment is more efficient. In addition, SCC-13 cell derived cancer stem cells are more responsive to these agents than non-stem cancer cells. Both agents suppress tumor formation, but enhanced suppression is observed with combined treatment. Moreover, both agents reduce the number of tumor-resident cancer stem cells. SFN treatment of cultured cells or tumors increases apoptosis and p21 Cip1 level, and both agents increase tumor apoptosis. We suggest that combined therapy with sulforaphane and cisplatin is efficient in suppressing tumor formation and may be a treatment option for advanced epidermal squamous cell carcinoma. © 2017 Wiley Periodicals, Inc.

Response of mouse epidermal cells to single doses of heavy-particles

NASA Technical Reports Server (NTRS)

Leith, J. T.; Schilling, W. A.; Welch, G. P.

1972-01-01

The survival of mouse epidermal cells to heavy-particles has been studied In Vivo by the Withers clone technique. Experiments with accelerated helium, lithium and carbon ions were performed. The survival curve for the helium ion irradiations used a modified Bragg curve method with a maximum tissue penetration of 465 microns, and indicated that the dose needed to reduce the original cell number to 1 surviving cell/square centimeters was 1525 rads with a D sub o of 95 rads. The LET at the basal cell layer was 28.6 keV per micron. Preliminary experiments with lithium and carbon used treatment doses of 1250 rads with LET's at the surface of the skin of 56 and 193 keV per micron respectively. Penetration depths in skin were 350 and 530 microns for the carbon and lithium ions whose Bragg curves were unmodified. Results indicate a maximum RBE for skin of about 2 using the skin cloning technique. An attempt has been made to relate the epidermal cell survival curve to mortality of the whole animal for helium ions.

Combining laser-assisted microdissection (LAM) and RNA-seq allows to perform a comprehensive transcriptomic analysis of epidermal cells of Arabidopsis embryo.

PubMed

Sakai, Kaori; Taconnat, Ludivine; Borrega, Nero; Yansouni, Jennifer; Brunaud, Véronique; Paysant-Le Roux, Christine; Delannoy, Etienne; Martin Magniette, Marie-Laure; Lepiniec, Loïc; Faure, Jean Denis; Balzergue, Sandrine; Dubreucq, Bertrand

2018-01-01

Genome-wide characterization of tissue- or cell-specific gene expression is a recurrent bottleneck in biology. We have developed a sensitive approach based on ultra-low RNA sequencing coupled to laser assisted microdissection for analyzing different tissues of the small Arabidopsis embryo. We first characterized the number of genes detected according to the quantity of tissue yield and total RNA extracted. Our results revealed that as low as 0.02 mm 2 of tissue and 50 pg of total RNA can be used without compromising the number of genes detected. The optimised protocol was used to compare the epidermal versus mesophyll cell transcriptomes of cotyledons at the torpedo-shaped stage of embryo development. The approach was validated by the recovery of well-known epidermal genes such AtML1 or AtPDF2 and genes involved in flavonoid and cuticular waxes pathways. Moreover, the interest and sensitivity of this approach were highlighted by the characterization of several transcription factors preferentially expressed in epidermal cells. This technical advance unlocks some current limitations of transcriptomic analyses and allows to investigate further and efficiently new biological questions for which only a very small amounts of cells need to be isolated. For instance, it paves the way to increasing the spatial accuracy of regulatory networks in developing small embryo of Arabidopsis or other plant tissues.

Intradermal injection of an anti-Langerin-HIVGag fusion vaccine targets epidermal Langerhans cells in nonhuman primates and can be tracked in vivo.

PubMed

Salabert, Nina; Todorova, Biliana; Martinon, Frédéric; Boisgard, Raphaël; Zurawski, Gerard; Zurawski, Sandra; Dereuddre-Bosquet, Nathalie; Cosma, Antonio; Kortulewski, Thierry; Banchereau, Jacques; Levy, Yves; Le Grand, Roger; Chapon, Catherine

2016-03-01

The development of new immunization strategies requires a better understanding of early molecular and cellular events occurring at the site of injection. The skin is particularly rich in immune cells and represents an attractive site for vaccine administration. Here, we specifically targeted vaccine antigens to epidermal Langerhans cells (LCs) using a fusion protein composed of HIV antigens and a monoclonal antibody targeting Langerin. We developed a fluorescence imaging approach to visualize, in vivo, the vaccine-targeted cells. Studies were performed in nonhuman primates (NHPs) because of their relevance as a model to assess human vaccines. We directly demonstrated that in NHPs, intradermally injected anti-Langerin-HIVGag specifically targets epidermal LCs and induces rapid changes in the LC network, including LC activation and migration out of the epidermis. Vaccine targeting of LCs significantly improved anti-HIV immune response without requirement of an adjuvant. Although the co-injection of the TLR-7/8 synthetic ligand, R-848 (resiquimod), with the vaccine, did not enhance significantly the antibody response, it stimulated recruitment of HLA-DR+ inflammatory cells to the site of immunization. This study allowed us to characterize the dynamics of early local events following the injection of a vaccine-targeted epidermal LCs and R-848. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Turnover of pigment granules: cyclic catabolism and anabolism of ommochromes within epidermal cells.

PubMed

Insausti, T C; Casas, J

2009-12-01

Ommochromes are end products of the tryptophan metabolism in arthropods. While the anabolism of ommochromes has been well studied, the catabolism is totally unknown. In order to study it, we used the crab-spider Misumena vatia, which is able to change color reversibly in a few days, from yellow to white and back. Ommochromes is the only pigment class responsible for the body coloration in this animal. The aim of this study was to analyze the fine structure of the epidermal cells in bleaching spiders, in an attempt to correlate morphological changes with the fate of the pigment granules. Central to the process of bleaching is the lysis of the ommochrome granules. In the same cell, intact granules and granules in different degradation stages are found. The degradation begins with granule autolysis. Some components are extruded in the extracellular space and others are recycled via autophagy. Abundant glycogen appears associated to granulolysis. In a later stage of bleaching, ommochrome progranules, typical of white spiders, appear in the distal zone of the same epidermal cell. Catabolism and anabolism of pigment granules thus take place simultaneously in spider epidermal cells. A cyclic pathway of pigment granules formation and degradation, throughout a complete cycle of color change is proposed, together with an explanation for this turnover, involving photoprotection against UV by ommochromes metabolites. The presence of this turnover for melanins is discussed.

Involvement of auxin and a homeodomain-leucine zipper I gene in rhizoid development of the moss Physcomitrella patens.

PubMed

Sakakibara, Keiko; Nishiyama, Tomoaki; Sumikawa, Naomi; Kofuji, Rumiko; Murata, Takashi; Hasebe, Mitsuyasu

2003-10-01

Differentiation of epidermal cells is important for plants because they are in direct contact with the environment. Rhizoids are multicellular filaments that develop from the epidermis in a wide range of plants, including pteridophytes, bryophytes, and green algae; they have similar functions to root hairs in vascular plants in that they support the plant body and are involved in water and nutrient absorption. In this study, we examined mechanisms underlying rhizoid development in the moss, Physcomitrella patens, which is the only land plant in which high-frequency gene targeting is possible. We found that rhizoid development can be split into two processes: determination and differentiation. Two types of rhizoids with distinct developmental patterns (basal and mid-stem rhizoids) were recognized. The development of basal rhizoids from epidermal cells was induced by exogenous auxin, while that of mid-stem rhizoids required an unknown factor in addition to exogenous auxin. Once an epidermal cell had acquired a rhizoid initial cell fate, expression of the homeodomain-leucine zipper I gene Pphb7 was induced. Analysis of Pphb7 disruptant lines showed that Pphb7 affects the induction of pigmentation and the increase in the number and size of chloroplasts, but not the position or number of rhizoids. This is the first report on the involvement of a homeodomain-leucine zipper I gene in epidermal cell differentiation.

Epidermal growth factor receptor in non-small cell lung cancer

PubMed Central

2015-01-01

Following the identification of a group of patients in the initial tyrosine kinase inhibitor (TKI) trials for lung cancer, there has been detailed focus on which patients may benefit from inhibitor therapy. This article reviews the background, genetics and prevalence of epidermal growth factor mutations in non-small cell lung cancer (NSCLC). Additionally, the prevalence in unselected patients is compared against various other reviews. PMID:25870793

Fabricated autologous epidermal cell sheets for the prevention of esophageal stricture after circumferential ESD in a porcine model.

PubMed

Kanai, Nobuo; Yamato, Masayuki; Ohki, Takeshi; Yamamoto, Masakazu; Okano, Teruo

2012-10-01

Endoscopic submucosal dissection (ESD) is an accepted treatment for early esophageal carcinoma. However, resection of a large mucosal area, as with circumferential ESD, induces severe stricture formation. To evaluate the efficacy of cultured autologous epidermal cell sheets to prevent severe esophageal constriction after circumferential ESD. Animal study. University institute. Eight pigs underwent circumferential esophageal ESD while under general anesthesia. In 4 pigs, fabricated autologous epidermal cell sheets were endoscopically transplanted to the central ESD sites immediately after the ESD. The other 4 pigs underwent circumferential ESD only. Necropsy and histological assessment were performed at 1 and 2 weeks post-ESD. Weight gain, degree of mucosal constriction, and histological assessments. All pigs in the control group showed severe esophageal constriction after 2 weeks. The control and transplanted groups had weight gains of -10.3% and 0.3% (P = .03), respectively, and the mean degrees of constriction were 88% and 56% (P < .01), respectively. Early re-epithelialization and mild fibrosis in the muscularis were observed in the transplanted group. Animal study, small sample size. Fabricated autologous skin epidermal cell sheets would be useful in preventing severe esophageal constriction after circumferential ESD. Copyright © 2012 American Society for Gastrointestinal Endoscopy. Published by Mosby, Inc. All rights reserved.

The involvement of J-protein AtDjC17 in root development in Arabidopsis

PubMed Central

Petti, Carloalberto; Nair, Meera; DeBolt, Seth

2014-01-01

In a screen for root hair morphogenesis mutants in Arabidopsis thaliana L. we identified a T-DNA insertion within a type III J-protein AtDjC17 caused altered root hair development and reduced hair length. Root hairs were observed to develop from trichoblast and atrichoblast cell files in both Atdjc17 and 35S::AtDJC17. Localization of gene expression in the root using transgenic plants expressing proAtDjC17::GUS revealed constitutive expression in stele cells. No AtDJC17 expression was observed in epidermal, endodermal, or cortical layers. To explore the contrast between gene expression in the stele and epidermal phenotype, hand cut transverse sections of Atdjc17 roots were examined showing that the endodermal and cortical cell layers displayed increased anticlinal cell divisions. Aberrant cortical cell division in Atdjc17 is proposed as causal in ectopic root hair formation via the positional cue requirement that exists between cortical and epidermal cell in hair cell fate determination. Results indicate a requirement for AtDJC17 in position-dependent cell fate determination and illustrate an intriguing requirement for molecular co-chaperone activity during root development. PMID:25339971

Human corpus luteum: presence of epidermal growth factor receptors and binding characteristics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ayyagari, R.R.; Khan-Dawood, F.S.

Epidermal growth factor receptors are present in many reproductive tissues but have not been demonstrated in the human corpus luteum. To determine the presence of epidermal growth factor receptors and its binding characteristics, we carried out studies on the plasma cell membrane fraction of seven human corpora lutea (days 16 to 25) of the menstrual cycle. Specific epidermal growth factor receptors were present in human corpus luteum. Insulin, nerve growth factor, and human chorionic gonadotropin did not competitively displace epidermal growth factor binding. The optimal conditions for corpus luteum-epidermal growth factor receptor binding were found to be incubation for 2more » hours at 4 degrees C with 500 micrograms plasma membrane protein and 140 femtomol /sup 125/I-epidermal growth factor per incubate. The number (mean +/- SEM) of epidermal growth factor binding sites was 12.34 +/- 2.99 X 10(-19) mol/micrograms protein; the dissociation constant was 2.26 +/- 0.56 X 10(-9) mol/L; the association constant was 0.59 +/- 0.12 X 10(9) L/mol. In two regressing corpora lutea obtained on days 2 and 3 of the menstrual cycle, there was no detectable specific epidermal growth factor receptor binding activity. Similarly no epidermal growth factor receptor binding activity could be detected in ovarian stromal tissue. Our findings demonstrate that specific receptors for epidermal growth factor are present in the human corpus luteum. The physiologic significance of epidermal growth factor receptors in human corpus luteum is unknown, but epidermal growth factor may be involved in intragonadal regulation of luteal function.« less

Keratin-6 driven ODC expression to hair follicle keratinocytes enhances stemness and tumorigenesis by negatively regulating Notch

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arumugam, Aadithya; Weng, Zhiping; Chaudhary, Sandeep C.

Highlights: • Targeting ODC to hair follicle augments skin carcinogenesis and invasive SCCs. • Hair follicle ODC expands stem cell compartment carrying CD34{sup +}/K15{sup +}/p63{sup +} keratinocytes. • Negatively regulated Notch1 is associated with expansion of stem cell compartment. - Abstract: Over-expression of ornithine decarboxylase (ODC) is known to be involved in the epidermal carcinogenesis. However, the mechanism by which it enhances skin carcinogenesis remains undefined. Recently, role of stem cells localized in various epidermal compartments has been shown in the pathogenesis of skin cancer. To direct ODC expression in distinct epidermal compartments, we have developed keratin 6 (K6)-ODC/SKH-1 andmore » keratin 14 (K14)-ODC/SKH-1 mice and employed them to investigate the role of ODC directed to these epidermal compartments on UVB-induced carcinogenesis. K6-driven ODC over-expression directed to outer root sheath (ORS) of hair follicle was more effective in augmenting tumorigenesis as compared to mice where K14-driven ODC expression was directed to inter-follicular epidermal keratinocytes. Chronically UVB-irradiated K6-ODC/SKH-1 developed 15 ± 2.5 tumors/mouse whereas K14-ODC/SKH-1 developed only 6.8 ± 1.5 tumors/mouse. K6-ODC/SKH-1 showed augmented UVB-induced proliferation and much higher pro-inflammatory responses than K14-ODC/SKH-1 mice. Tumors induced in K6-ODC/SKH-1 were rapidly growing, invasive and ulcerative squamous cell carcinoma (SCC) showing decreased expression of epidermal polarity marker E-cadherin and enhanced mesenchymal marker, fibronectin. Interestingly, the number of CD34/CK15/p63 positive stem-like cells was significantly higher in chronically UVB-irradiated K6-ODC/SKH-1 as compared to K14-ODC/SKH-1 mice. Reduced Notch1 expression was correlated with the expansion of stem cell compartment in these animals. However, other signaling pathways such as DNA damage response or mTOR signaling pathways were not significantly different in tumors induced in these two murine models suggesting the specificity of Notch pathway in this regard. These data provide a novel role of ODC in augmenting tumorigenesis via negatively regulated Notch-mediated expansion of stem cell compartment.« less

Morphology of the Epidermis of the Neotropical Catfish Pimelodella lateristriga (Lichtenstein, 1823) with Emphasis in Club Cells

PubMed Central

Damasceno, Eduardo Medeiros; Monteiro, Juliana Castro; Duboc, Luiz Fernando; Dolder, Heidi; Mancini, Karina

2012-01-01

The epidermis of Ostariophysi fish is composed of 4 main cell types: epidermal cells (or filament containing cells), mucous cells, granular cells and club cells. The morphological analysis of the epidermis of the catfish Pimelodella lateristriga revealed the presence of only two types of cells: epidermal and club cells. The latter were evident in the middle layer of the epidermis, being the largest cells within the epithelium. Few organelles were located in the perinuclear region, while the rest of the cytoplasm was filled with a non-vesicular fibrillar substance. Club cells contained two irregular nuclei with evident nucleoli and high compacted peripheral chromatin. Histochemical analysis detected prevalence of protein within the cytoplasm other than carbohydrates, which were absent. These characteristics are similar to those described to most Ostariophysi studied so far. On the other hand, the epidermal cells differ from what is found in the literature. The present study described three distinct types, as follows: superficial, abundant and dense cells. Differences among them were restricted to their cytoplasm and nucleus morphology. Mucous cells were found in all Ostariophysi studied so far, although they were absent in P. lateristriga, along with granular cells, also typical of other catfish epidermis. The preset study corroborates the observations on club cells' morphology in Siluriformes specimens, and shows important differences in epidermis composition and cell structure of P. lateristriga regarding the literature data. PMID:23226253

Quantifying the plant actin cytoskeleton response to applied pressure using nanoindentation.

PubMed

Branco, Rémi; Pearsall, Eliza-Jane; Rundle, Chelsea A; White, Rosemary G; Bradby, Jodie E; Hardham, Adrienne R

2017-03-01

Detection of potentially pathogenic microbes through recognition by plants and animals of both physical and chemical signals associated with the pathogens is vital for host well-being. Signal perception leads to the induction of a variety of responses that augment pre-existing, constitutive defences. The plant cell wall is a highly effective preformed barrier which becomes locally reinforced at the infection site through delivery of new wall material by the actin cytoskeleton. Although mechanical stimulation can produce a reaction, there is little understanding of the nature of physical factors capable of triggering plant defence. Neither the magnitude of forces nor the contact time required has been quantified. In the study reported here, mechanical stimulation with a tungsten microneedle has been used to quantify the response of Arabidopsis plants expressing an actin-binding protein tagged with green fluorescent protein (GFP) to reveal the organisation of the actin cytoskeleton. Using confocal microscopy, the response time for actin reorganisation in epidermal cells of Arabidopsis hypocotyls was shown to be 116 ± 49 s. Using nanoindentation and a diamond spherical tip indenter, the magnitude of the forces capable of triggering an actin response has been quantified. We show that Arabidopsis hypocotyl cells can detect a force as small as 4 μN applied for as short a time as 21.6 s to trigger reorganisation of the actin cytoskeleton. This force is an order of magnitude less than the potential invasive force determined for a range of fungal and oomycete plant pathogens. To our knowledge, this is the first quantification of the magnitude and duration of mechanical forces capable of stimulating a structural defence response in a plant cell.

Epidermal keratinocytes initiate wound healing and pro-inflammatory immune responses following percutaneous schistosome infection

PubMed Central

Bourke, Claire D.; Prendergast, Catriona T.; Sanin, David E.; Oulton, Tate E.; Hall, Rebecca J.; Mountford, Adrian P.

2015-01-01

Keratinocytes constitute the majority of cells in the skin’s epidermis, the first line of defence against percutaneous pathogens. Schistosome larvae (cercariae) actively penetrate the epidermis to establish infection, however the response of keratinocytes to invading cercariae has not been investigated. Here we address the hypothesis that cercariae activate epidermal keratinocytes to promote the development of a pro-inflammatory immune response in the skin. C57BL/6 mice were exposed to Schistosoma mansoni cercariae via each pinna and non-haematopoietic cells isolated from epidermal tissue were characterised for the presence of different keratinocyte sub-sets at 6, 24 and 96 h p.i. We identified an expansion of epidermal keratinocyte precursors (CD45−, CD326−, CD34+) within 24 h of infection relative to naïve animals. Following infection, cells within the precursor population displayed a more differentiated phenotype (α6integrin−) than in uninfected skin. Parallel immunohistochemical analysis of pinnae cryosections showed that this expansion corresponded to an increase in the intensity of CD34 staining, specifically in the basal bulge region of hair follicles of infected mice, and a higher frequency of keratinocyte Ki67+ nuclei in both the hair follicle and interfollicular epidermis. Expression of pro-inflammatory cytokine and stress-associated keratin 6b genes was also transiently upregulated in the epidermal tissue of infected mice. In vitro exposure of keratinocyte precursors isolated from neonatal mouse skin to excretory/secretory antigens released by penetrating cercariae elicited IL-1α and IL-1β production, supporting a role for keratinocyte precursors in initiating cutaneous inflammatory immune responses. Together, these observations indicate that S.mansoni cercariae and their excretory/secretory products act directly upon epidermal keratinocytes, which respond by initiating barrier repair and pro-inflammatory mechanisms similar to those observed in epidermal wound healing. PMID:25575749

Herbicidal cyanoacrylates with antimicrotubule mechanism of action.

PubMed

Tresch, Stefan; Plath, Peter; Grossmann, Klaus

2005-11-01

The herbicidal mode of action of the new synthetic cyanoacrylates ethyl (2Z)-3-amino-2-cyano-4-ethylhex-2-enoate (CA1) and its isopropyl ester derivative CA2 was investigated. For initial characterization, a series of bioassays was used indicating a mode of action similar to that of mitotic disrupter herbicides such as the dinitroaniline pendimethalin. Cytochemical fluorescence studies including monoclonal antibodies against polymerized and depolymerized tubulin and a cellulose-binding domain of a bacterial cellulase conjugated to a fluorescent dye were applied to elucidate effects on cell division processes including mitosis and microtubule and cell wall formation in maize roots. When seedlings were root treated with 10 microM of CA1 or CA2, cell division activity in meristematic root tip cells decreased within 4 h. The chromosomes proceeded to a condensed state of prometaphase, but were unable to progress further in the mitotic cycle. The compounds caused a complete loss of microtubular structures, including preprophase, spindle, phragmoplast and cortical microtubules. Concomitantly, in the cytoplasm, an increase in labelling of free tubulin was observed. This suggests that the herbicides disrupt polymerization and microtubule stability, whereas tubulin synthesis or degradation appeared not to be affected. In addition, cellulose labelling in cell walls of root tip cells was not influenced. The effects of CA1 and CA2 were comparable with those caused by pendimethalin. In transgenic Arabidopsis plants expressing a green fluorescent protein-microtubule-associated protein4 fusion protein, labelled arrays of cortical microtubules in living epidermal cells of hypocotyls collapsed within 160 min after exposure to 10 microM CA1 or pendimethalin. Moreover, a dinitroaniline-resistant biotype of goosegrass (Eleusine indica (L) Gaertn) with a point mutation in alpha-tubulin showed cross-resistance against CA1 and CA2. The results strongly indicate that the cyanoacrylates are a new chemical class of herbicide which possess the same antimicrotubule mechanism of action as dinitroanilines, probably including interaction with the same binding site in alpha-tubulin. Copyright 2005 Society of Chemical Industry.

Differential Lipid Composition and Gene Expression in the Semi-Russeted “Cox Orange Pippin” Apple Variety

PubMed Central

Legay, Sylvain; Cocco, Emmanuelle; André, Christelle M.; Guignard, Cédric; Hausman, Jean-Francois; Guerriero, Gea

2017-01-01

Russeting is characterized by a particular rough and brown phenotype, which is mainly due to the accumulation of suberin in the inner part of the epidermal cell walls. In our previous bulk transcriptomic analysis, comparing fully russeted, and waxy apple varieties, showed, in apple fruit skin, a massive decreased expression of cutin, wax and some pentacyclic triterpene biosynthesis genes in the russeted varieties, with an expected concomitant enhanced expression of the suberin biosynthetic genes. In the present work, we performed a deep investigation of the aliphatic composition of the cutin, suberin, waxes, and triterpenes in the waxy and russeted patches of the semi-russeted apple variety “Cox Orange Pippin.” A targeted gene expression profiling was performed to validate candidate genes which were identified in our previous work and might be involved in the respective metabolic pathways. Our results showed that a decrease of cuticular waxes, ursolic acid and oleanolic acid, accompanied by an accumulation of alkyl-hydroxycinamates and betulinic acid, occurs in the russeted patches. The suberin monomer composition is characterized by specific occurrence of 20, 22, and 24 carbon aliphatic chains, whereas cutin is mainly represented by common C16 and C18 aliphatic chains. This work depicts, for the first time in apple, the complex composition of suberin, cutin, waxes and triterpenes, and confirms the strong interplay between these epidermal polymers in apple fruit skin. PMID:29018466

Differential Lipid Composition and Gene Expression in the Semi-Russeted "Cox Orange Pippin" Apple Variety.

PubMed

Legay, Sylvain; Cocco, Emmanuelle; André, Christelle M; Guignard, Cédric; Hausman, Jean-Francois; Guerriero, Gea

2017-01-01

Russeting is characterized by a particular rough and brown phenotype, which is mainly due to the accumulation of suberin in the inner part of the epidermal cell walls. In our previous bulk transcriptomic analysis, comparing fully russeted, and waxy apple varieties, showed, in apple fruit skin, a massive decreased expression of cutin, wax and some pentacyclic triterpene biosynthesis genes in the russeted varieties, with an expected concomitant enhanced expression of the suberin biosynthetic genes. In the present work, we performed a deep investigation of the aliphatic composition of the cutin, suberin, waxes, and triterpenes in the waxy and russeted patches of the semi-russeted apple variety "Cox Orange Pippin." A targeted gene expression profiling was performed to validate candidate genes which were identified in our previous work and might be involved in the respective metabolic pathways. Our results showed that a decrease of cuticular waxes, ursolic acid and oleanolic acid, accompanied by an accumulation of alkyl-hydroxycinamates and betulinic acid, occurs in the russeted patches. The suberin monomer composition is characterized by specific occurrence of 20, 22, and 24 carbon aliphatic chains, whereas cutin is mainly represented by common C16 and C18 aliphatic chains. This work depicts, for the first time in apple, the complex composition of suberin, cutin, waxes and triterpenes, and confirms the strong interplay between these epidermal polymers in apple fruit skin.

Characterization of the Expression of the Petunia Glycine-Rich Protein-1 Gene Product 1

PubMed Central

Condit, Carol M.; McLean, B. Gail; Meagher, Richard B.

1990-01-01

We have examined the expression of the petunia (Petunia hybrida) glycine-rich protein-1 (ptGRP1) gene product using an antibody raised against a synthetic peptide comprising amino acids 22 through 36 of the mature ptGRP1 protein. This antibody recognizes a single protein of 23 kilodaltons. Cell fractionation studies showed that, as predicted (CM Condit, RB Meagher [1986] Nature 323: 178-181), ptGRP1 is most likely localized in the cell wall. In addition, it was found that (extractable) ptGRP1 is present in much higher abundance in unexpanded than in fully expanded tissue, with highest levels of accumulation in the bud. This same developmentally regulated pattern of protein expression was found in all varieties of petunia tested. In addition, tissue blots of petunia stem sections showed that ptGRP1 is localized to within the vascular tissue (to at least the phloem or cambium) and to either the epidermal cells or to a layer of collenchyma cells directly below the epidermis. Localization of ptGRP1 antigen in these cell types is shown to occur at different times in the overall development of the plant and at different quantitative levels. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 PMID:16667509

microRNA-184 Induces a Commitment Switch to Epidermal Differentiation.

PubMed

Nagosa, Sara; Leesch, Friederike; Putin, Daria; Bhattacharya, Swarnabh; Altshuler, Anna; Serror, Laura; Amitai-Lange, Aya; Nasser, Waseem; Aberdam, Edith; Rouleau, Matthieu; Tattikota, Sudhir G; Poy, Matthew N; Aberdam, Daniel; Shalom-Feuerstein, Ruby

2017-12-12

miR-184 is a highly evolutionary conserved microRNA (miRNA) from fly to human. The importance of miR-184 was underscored by the discovery that point mutations in miR-184 gene led to corneal/lens blinding disease. However, miR-184-related function in vivo remained unclear. Here, we report that the miR-184 knockout mouse model displayed increased p63 expression in line with epidermal hyperplasia, while forced expression of miR-184 by stem/progenitor cells enhanced the Notch pathway and induced epidermal hypoplasia. In line, miR-184 reduced clonogenicity and accelerated differentiation of human epidermal cells. We showed that by directly repressing cytokeratin 15 (K15) and FIH1, miR-184 induces Notch activation and epidermal differentiation. The disease-causing miR-184 C57U mutant failed to repress K15 and FIH1 and to induce Notch activation, suggesting a loss-of-function mechanism. Altogether, we propose that, by targeting K15 and FIH1, miR-184 regulates the transition from proliferation to early differentiation, while mis-expression or mutation in miR-184 results in impaired homeostasis. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Epidermal growth factor induction of front–rear polarity and migration in keratinocytes is mediated by integrin-linked kinase and ELMO2

PubMed Central

Ho, Ernest; Dagnino, Lina

2012-01-01

Epidermal growth factor (EGF) is a potent chemotactic and mitogenic factor for epidermal keratinocytes, and these properties are central for normal epidermal regeneration after injury. The involvement of mitogen-activated protein kinases as mediators of the proliferative effects of EGF is well established. However, the molecular mechanisms that mediate motogenic responses to this growth factor are not clearly understood. An obligatory step for forward cell migration is the development of front–rear polarity and formation of lamellipodia at the leading edge. We show that stimulation of epidermal keratinocytes with EGF, but not with other growth factors, induces development of front–rear polarity and directional migration through a pathway that requires integrin-linked kinase (ILK), Engulfment and Cell Motility-2 (ELMO2), integrin β1, and Rac1. Furthermore, EGF induction of front–rear polarity and chemotaxis require the tyrosine kinase activity of the EGF receptor and are mediated by complexes containing active RhoG, ELMO2, and ILK. Our findings reveal a novel link between EGF receptor stimulation, ILK-containing complexes, and activation of small Rho GTPases necessary for acquisition of front–rear polarity and forward movement. PMID:22160594

Epidermal growth factor induction of front-rear polarity and migration in keratinocytes is mediated by integrin-linked kinase and ELMO2.

PubMed

Ho, Ernest; Dagnino, Lina

2012-02-01

Epidermal growth factor (EGF) is a potent chemotactic and mitogenic factor for epidermal keratinocytes, and these properties are central for normal epidermal regeneration after injury. The involvement of mitogen-activated protein kinases as mediators of the proliferative effects of EGF is well established. However, the molecular mechanisms that mediate motogenic responses to this growth factor are not clearly understood. An obligatory step for forward cell migration is the development of front-rear polarity and formation of lamellipodia at the leading edge. We show that stimulation of epidermal keratinocytes with EGF, but not with other growth factors, induces development of front-rear polarity and directional migration through a pathway that requires integrin-linked kinase (ILK), Engulfment and Cell Motility-2 (ELMO2), integrin β1, and Rac1. Furthermore, EGF induction of front-rear polarity and chemotaxis require the tyrosine kinase activity of the EGF receptor and are mediated by complexes containing active RhoG, ELMO2, and ILK. Our findings reveal a novel link between EGF receptor stimulation, ILK-containing complexes, and activation of small Rho GTPases necessary for acquisition of front-rear polarity and forward movement.

Malignant Change in an Epidermal Cyst Over Gluteal Region

PubMed Central

Kshirsagar, Ashok Y; Sulhyan, Sanjitsingh R; Deshpande, Shradha; Jagtap, SV

2011-01-01

A 72-year-old male presented with a large ulceroproliferative lesion over left gluteal region. After histopathological confirmation of squamous cell carcinoma, the lesion was excised with wide margins. Further histopathological study of the excised specimen revealed the growth arising from an epidermal cyst. Malignant change is a rare, but wellknown complication occurring in an epidermal cyst. The mainstay of treatment consists of wide excision of cancerous lesion with primary reconstruction of the defect. PMID:21572684

Mammalian skin cell biology: at the interface between laboratory and clinic.

PubMed

Watt, Fiona M

2014-11-21

Mammalian skin research represents the convergence of three complementary disciplines: cell biology, mouse genetics, and dermatology. The skin provides a paradigm for current research in cell adhesion, inflammation, and tissue stem cells. Here, I discuss recent insights into the cell biology of skin. Single-cell analysis has revealed that human epidermal stem cells are heterogeneous and differentiate in response to multiple extrinsic signals. Live-cell imaging, optogenetics, and cell ablation experiments show skin cells to be remarkably dynamic. High-throughput, genome-wide approaches have yielded unprecedented insights into the circuitry that controls epidermal stem cell fate. Last, integrative biological analysis of human skin disorders has revealed unexpected functions for elements of the skin that were previously considered purely structural. Copyright © 2014, American Association for the Advancement of Science.

Hormonal regulation of growth and life span of bullfrog tadpole tail epidermal cells cultured in vitro.

PubMed

Nishikawa, A; Yoshizato, K

1986-02-01

Epidermal cells were dissociated from tails of the bullfrog tadpole, Rana catesbeiana, and cultured to investigate their response to steroid and thyroid hormones. Charcoal-treated serum (CTS) was used in the growth medium when cells were to be grown in the absence of steroid and thyroid hormones. The cells could be maintained for 2 weeks with a small increase in cell number in medium that contained CTS (CTS medium). Addition of cortisol to CTS medium increased both cellular attachment to the culture dishes and the proliferation of the attached cells with an optimum concentration of 5 X 10(-7) M. The cells remained viable and attached for at least a week. Cortisol stimulated the rate of protein synthesis 1.8-fold but did not alter the rate of DNA synthesis. The cells did not proliferate in the medium containing triiodothyronine (T3) and detached themselves from the dish within 5 days, which occurred in a dose-dependent manner with a maximum effect at 10(-8) M. It drastically decreased the rate of DNA synthesis but did not influence the rate of protein synthesis. These responses of cells to cortisol and T3 may reflect growth and death of tail epidermal cells in vivo at metamorphosis.

Positional signaling mediated by a receptor-like kinase in Arabidopsis.

PubMed

Kwak, Su-Hwan; Shen, Ronglai; Schiefelbein, John

2005-02-18

The position-dependent specification of root epidermal cells in Arabidopsis provides an elegant paradigm for cell patterning during development. Here, we describe a new gene, SCRAMBLED (SCM), required for cells to appropriately interpret their location within the developing root epidermis. SCM encodes a receptor-like kinase protein with a predicted extracellular domain of six leucine-rich repeats and an intracellular serine-threonine kinase domain. SCM regulates the expression of the GLABRA2, CAPRICE, WEREWOLF, and ENHANCER OF GLABRA3 transcription factor genes that define the cell fates. Further, the SCM gene is expressed throughout the developing root. Therefore, SCM likely enables developing epidermal cells to detect positional cues and establish an appropriate cell-type pattern.

Expression of an Exogenous Growth Hormone Gene by Transplantable Human Epidermal Cells

NASA Astrophysics Data System (ADS)

Morgan, Jeffrey R.; Barrandon, Yann; Green, Howard; Mulligan, Richard C.

1987-09-01

Retrovirus-mediated gene transfer was used to introduce a recombinant human growth hormone gene into cultured human keratinocytes. The transduced keratinocytes secreted biologically active growth hormone into the culture medium. When grafted as an epithelial sheet onto athymic mice, these cultured keratinocytes reconstituted an epidermis that was similar in appearance to that resulting from normal cells, but from which human growth hormone could be extracted. Transduced epidermal cells may prove to be a general vehicle for the delivery of gene products by means of grafting.

UV radiation induces CXCL5 expression in human skin.

PubMed

Reichert, Olga; Kolbe, Ludger; Terstegen, Lara; Staeb, Franz; Wenck, Horst; Schmelz, Martin; Genth, Harald; Kaever, Volkhard; Roggenkamp, Dennis; Neufang, Gitta

2015-04-01

CXCL5 has recently been identified as a mediator of UVB-induced pain in rodents. To compare and to extend previous knowledge of cutaneous CXCL5 regulation, we performed a comprehensive study on the effects of UV radiation on CXCL5 regulation in human skin. Our results show a dose-dependent increase in CXCL5 protein in human skin after UV radiation. CXCL5 can be released by different cell types in the skin. We presumed that, in addition to immune cells, non-immune skin cells also contribute to UV-induced increase in CXCL5 protein. Analysis of monocultured dermal fibroblasts and keratinocytes revealed that only fibroblasts but not keratinocytes displayed up regulated CXCL5 levels after UV stimulation. Whereas UV treatment of human skin equivalents, induced epidermal CXCL5 mRNA and protein expression. Up regulation of epidermal CXCL5 was independent of keratinocyte differentiation and keratinocyte-keratinocyte interactions in epidermal layers. Our findings provide first evidence on the release of CXCL5 in UV-radiated human skin and the essential role of fibroblast-keratinocyte interaction in the regulation of epidermal CXCL5. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Development of 3D imaging technique of reconstructed human epidermis with immortalized human epidermal cell line.

PubMed

Inoue, Yu; Hasegawa, Seiji; Miyachi, Katsuma; Yamada, Takaaki; Nakata, Satoru; Ipponjima, Sari; Hibi, Terumasa; Nemoto, Tomomi; Tanaka, Masahiko; Suzuki, Ryo; Hirashima, Naohide

2018-05-01

The epidermis, the outermost layer of the skin, retains moisture and functions as a physical barrier against the external environment. Epidermal cells are continuously replaced by turnover, and thus to understand in detail the dynamic cellular events in the epidermis, techniques to observe live tissues in 3D are required. Here, we established a live 3D imaging technique for epidermis models. We first obtained immortalized human epidermal cell lines which have a normal differentiation capacity and fluorescence-labelled cytoplasm or nuclei. The reconstituted 3D epidermis was prepared with these lines. Using this culture system, we were able to observe the structure of the reconstituted epidermis live in 3D, which was similar to an in vivo epidermis, and evaluate the effect of a skin irritant. This technique may be useful for dermatological science and drug development. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A severe form of epidermal nevus syndrome associated with brainstem and cerebellar malformations and neonatal medulloblastoma.

PubMed

Okumura, Akihisa; Lee, Tsubasa; Ikeno, Mitsuru; Shimojima, Keiko; Kajino, Kazunori; Inoue, Yuka; Yoshikawa, Naomi; Suganuma, Hiroki; Suzuki, Mitsuyoshi; Hisata, Ken; Shoji, Hiromichi; Takanashi, Jun-ichi; Barkovich, A James; Shimizu, Toshiaki; Yamamoto, Toshiyuki; Hayashi, Masaharu

2012-11-01

Here we report a boy with epidermal nevus syndrome associated with brainstem and cerebellar malformations and neonatal medulloblastoma. The patient had epidermal nevi and complicated brain malformations including macrocephaly with polymicrogyria, dysmorphic and enlarged midbrain tectum, enlarged cerebellar hemispheres with small and maloriented folia. The patient died after surgical resection of medulloblastoma which was newly recognized on MRI at 51 days of age. Postmortem pathological examinations showed very unique and bizarre malformation of the midbrain and hindbrain. The cerebellar cortex exhibited a coarse, irregular and bumpy surface, blurred border between the Purkinje cell layer and internal granule cell layer, and many foci of heterotopia in the cerebellar white matter. The brainstem showed multiple anomalies, including enlargement of superior colliculi, hypoplasia of pyramidal tracts and dysplasia of inferior olivary nuclei. The unusual constellation of brain malformations of our patient will widen the spectrum of epidermal nevus syndrome. Copyright © 2012 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

Congestive Heart Failure During Osimertinib Treatment for Epidermal Growth Factor Receptor (EGFR)-mutant Non-small Cell Lung Cancer (NSCLC).

PubMed

Watanabe, Hiromi; Ichihara, Eiki; Kano, Hirohisa; Ninomiya, Kiichiro; Tanimoto, Mitsune; Kiura, Katsuyuki

2017-08-15

We herein report a case of congestive heart failure which developed during osimertinib treatment. A 78-year-old woman presented with mild exertional dyspnea three weeks after starting osimertinib for the treatment of epidermal growth factor receptor (EGFR) T790M-positive non-small cell lung cancer. She was diagnosed with congestive heart failure caused by the osimertinib. In contrast to trastuzumab, a human epidermal growth factor receptor 2 (HER2) monoclonal antibody that often causes cardiac dysfunction, the causal relationship between osimertinib and cardiotoxicity has so far received little attention and thus remains unclear. However, it inhibits HER2 in addition to mutant EGFR, thereby potentially causing cardiotoxicity.

Congestive Heart Failure During Osimertinib Treatment for Epidermal Growth Factor Receptor (EGFR)-mutant Non-small Cell Lung Cancer (NSCLC)

PubMed Central

Watanabe, Hiromi; Ichihara, Eiki; Kano, Hirohisa; Ninomiya, Kiichiro; Tanimoto, Mitsune; Kiura, Katsuyuki

2017-01-01

We herein report a case of congestive heart failure which developed during osimertinib treatment. A 78-year-old woman presented with mild exertional dyspnea three weeks after starting osimertinib for the treatment of epidermal growth factor receptor (EGFR) T790M-positive non-small cell lung cancer. She was diagnosed with congestive heart failure caused by the osimertinib. In contrast to trastuzumab, a human epidermal growth factor receptor 2 (HER2) monoclonal antibody that often causes cardiac dysfunction, the causal relationship between osimertinib and cardiotoxicity has so far received little attention and thus remains unclear. However, it inhibits HER2 in addition to mutant EGFR, thereby potentially causing cardiotoxicity. PMID:28781309

Characterization of A Three-Dimensional Organotypic Co-Culture Skin Model for Epidermal Differentiation of Rat Adipose-Derived Stem Cells.

PubMed

Ghanavati, Zeinab; Orazizadeh, Mahmoud; Bayati, Vahid; Abbaspour, Mohammad Reza; Khorsandi, Layasadat; Mansouri, Esrafil; Neisi, Niloofar

2016-01-01

The organotypic co-culture is a well-known technique to examine cellular interactions and their roles in stem cell proliferation and differentiation. This study aims to evaluate the effects of dermal fibroblasts (DFs) on epidermal differentiation of adipose-derived stem cells (ASCs) using a three-dimensional (3D) organotypic co- culture technique. In this experimental research study, rat DFs and ASCs were isolated and cultured separately on electrospun polycaprolactone (PCL) matrices. The PCL matrices seeded by ASCs were superimposed on to the matrices seeded by DFs in order to create a 3D organotypic co-culture. In the control groups, PCL matrices seeded by ASCs were placed on matrices devoid of DFs. After 10 days, we assessed the expressions of keratinocyte-related genes by real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and expression of pan-cytokeratin protein by immunofluorescence in the differentiated keratinocyte-like cells from co- culture and control groups. Keratinocyte-like cell morphologies were also observed by scanning electron microscopy (SEM). The early, intermediate, and terminal differentiation keratinocyte markers-Cytokeratin14, Filaggrin, and Involucrin significantly expressed in the co-culture groups com- pared to the control ones (P<0.05). We observed pan-cytokeratin in keratinocyte-like cells of both groups by immunofluorescence. SEM observation of the co-culture groups showed that the differentiated keratinocyte-like cells developed a polygonal cobblestone shape, considered characteristic of keratinocytes. The 3D organotypic co-culture bilayered construct that consisted of DFs and ASCs was an effective technique for epidermal differentiation of ASCs. This co-culture might be useful for epidermal differentiation of stem cells for future applications in skin regeneration.

Characterization of A Three-Dimensional Organotypic Co-Culture Skin Model for Epidermal Differentiation of Rat Adipose-Derived Stem Cells

PubMed Central

Ghanavati, Zeinab; Orazizadeh, Mahmoud; Bayati, Vahid; Abbaspour, Mohammad Reza; Khorsandi, Layasadat; Mansouri, Esrafil; Neisi, Niloofar

2016-01-01

Objective The organotypic co-culture is a well-known technique to examine cellular interactions and their roles in stem cell proliferation and differentiation. This study aims to evaluate the effects of dermal fibroblasts (DFs) on epidermal differentiation of adipose-derived stem cells (ASCs) using a three-dimensional (3D) organotypic co- culture technique. Materials and Methods In this experimental research study, rat DFs and ASCs were isolated and cultured separately on electrospun polycaprolactone (PCL) matrices. The PCL matrices seeded by ASCs were superimposed on to the matrices seeded by DFs in order to create a 3D organotypic co-culture. In the control groups, PCL matrices seeded by ASCs were placed on matrices devoid of DFs. After 10 days, we assessed the expressions of keratinocyte-related genes by real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and expression of pan-cytokeratin protein by immunofluorescence in the differentiated keratinocyte-like cells from co- culture and control groups. Keratinocyte-like cell morphologies were also observed by scanning electron microscopy (SEM). Results The early, intermediate, and terminal differentiation keratinocyte markers-Cytokeratin14, Filaggrin, and Involucrin significantly expressed in the co-culture groups com- pared to the control ones (P<0.05). We observed pan-cytokeratin in keratinocyte-like cells of both groups by immunofluorescence. SEM observation of the co-culture groups showed that the differentiated keratinocyte-like cells developed a polygonal cobblestone shape, considered characteristic of keratinocytes. Conclusion The 3D organotypic co-culture bilayered construct that consisted of DFs and ASCs was an effective technique for epidermal differentiation of ASCs. This co-culture might be useful for epidermal differentiation of stem cells for future applications in skin regeneration. PMID:27602310

A genome-wide screen identifies YAP/WBP2 interplay conferring growth advantage on human epidermal stem cells

PubMed Central

Walko, Gernot; Woodhouse, Samuel; Pisco, Angela Oliveira; Rognoni, Emanuel; Liakath-Ali, Kifayathullah; Lichtenberger, Beate M.; Mishra, Ajay; Telerman, Stephanie B.; Viswanathan, Priyalakshmi; Logtenberg, Meike; Renz, Lisa M.; Donati, Giacomo; Quist, Sven R.; Watt, Fiona M.

2017-01-01

Individual human epidermal cells differ in their self-renewal ability. To uncover the molecular basis for this heterogeneity, we performed genome-wide pooled RNA interference screens and identified genes conferring a clonal growth advantage on normal and neoplastic (cutaneous squamous cell carcinoma, cSCC) human epidermal cells. The Hippo effector YAP was amongst the top positive growth regulators in both screens. By integrating the Hippo network interactome with our data sets, we identify WW-binding protein 2 (WBP2) as an important co-factor of YAP that enhances YAP/TEAD-mediated gene transcription. YAP and WPB2 are upregulated in actively proliferating cells of mouse and human epidermis and cSCC, and downregulated during terminal differentiation. WBP2 deletion in mouse skin results in reduced proliferation in neonatal and wounded adult epidermis. In reconstituted epidermis YAP/WBP2 activity is controlled by intercellular adhesion rather than canonical Hippo signalling. We propose that defective intercellular adhesion contributes to uncontrolled cSCC growth by preventing inhibition of YAP/WBP2. PMID:28332498

Plastid Ontogeny during Petal Development in Arabidopsis1

PubMed Central

Pyke, Kevin A.; Page, Anton M.

1998-01-01

Imaging of chlorophyll autofluorescence by confocal microscopy in intact whole petals of Arabidopsis thaliana has been used to analyze chloroplast development and redifferentiation during petal development. Young petals dissected from unopened buds contained green chloroplasts throughout their structure, but as the upper part of the petal lamina developed and expanded, plastids lost their chlorophyll and redifferentiated into leukoplasts, resulting in a white petal blade. Normal green chloroplasts remained in the stalk of the mature petal. In epidermal cells the chloroplasts were normal and green, in stark contrast with leaf epidermal cell plastids. In addition, the majority of these chloroplasts had dumbbell shapes, typical of dividing chloroplasts, and we suggest that the rapid expansion of petal epidermal cells may be a trigger for the initiation of chloroplast division. In petals of the Arabidopsis plastid division mutant arc6, the conversion of chloroplasts into leukoplasts was unaffected in spite of the greatly enlarged size and reduced number of arc6 chloroplasts in cells in the petal base, resulting in few enlarged leukoplasts in cells from the white lamina of arc6 petals. PMID:9489024

Chloroplast behaviour and interactions with other organelles in Arabidopsis thaliana pavement cells.

PubMed

Barton, Kiah A; Wozny, Michael R; Mathur, Neeta; Jaipargas, Erica-Ashley; Mathur, Jaideep

2018-01-29

Chloroplasts are a characteristic feature of green plants. Mesophyll cells possess the majority of chloroplasts and it is widely believed that, with the exception of guard cells, the epidermal layer in most higher plants does not contain chloroplasts. However, recent observations on Arabidopsis thaliana have shown a population of chloroplasts in pavement cells that are smaller than mesophyll chloroplasts and have a high stroma to grana ratio. Here, using stable transgenic lines expressing fluorescent proteins targeted to the plastid stroma, plasma membrane, endoplasmic reticulum, tonoplast, nucleus, mitochondria, peroxisomes, F-actin and microtubules, we characterize the spatiotemporal relationships between the pavement cell chloroplasts (PCCs) and their subcellular environment. Observations on the PCCs suggest a source-sink relationship between the epidermal and the mesophyll layers, and experiments with the Arabidopsis mutants glabra2 ( gl2 ) and immutans ( im ), which show altered epidermal plastid development, underscored their developmental plasticity. Our findings lay down the foundation for further investigations aimed at understanding the precise role and contributions of PCCs in plant interactions with the environment. © 2018. Published by The Company of Biologists Ltd.

Tenascin-C, proliferation and subendothelial fibronectin in progressive pulmonary vascular disease.

PubMed Central

Jones, P. L.; Cowan, K. N.; Rabinovitch, M.

1997-01-01

Progressive pulmonary hypertension is characterized by smooth muscle cell proliferation and migration leading to occlusive arterial lesions. Previously, using cultured smooth muscle cells, we demonstrated that epidermal growth factor (EGF)-dependent proliferation and migration are dependent on tenascin-C (Tn) and cellular fibronectin (Fn), respectively. In this study we applied immunohistochemistry to lung biopsy tissue from patients with congenital heart defects and pulmonary hypertension to determine how the distribution and intensity of Tn, EGF, proliferating cell nuclear antigen (PCNA), and Fn expression related to arterial abnormalities. With mildly increased wall thickness, minimal Tn, PCNA, and EGF was evident. With progressive hypertrophy, moderately intense foci of Tn were apparent in the adventitia, periendothelium, and occasionally the media but not consistently co-distributing with EGF and PCNA. With obstructive lesions, intense neointimal Tn expression co-localized with EGF and PCNA. Fn accumulation in the periendothelium increased with medial hypertrophy and became more widespread in a diffuse pattern with neointimal formation. The neointima was predominantly composed of alpha-smooth-muscle-actin-positive cells, occasional inflammatory cells with no evidence of apoptosis. These studies are consistent with Tn modulating EGF-dependent neointimal smooth muscle cell proliferation and Fn providing a gradient for smooth muscle cell migration from media to neointima. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 PMID:9094991

ΔNp63 is an ectodermal gatekeeper of epidermal morphogenesis

PubMed Central

Shalom-Feuerstein, R; Lena, A M; Zhou, H; De La Forest Divonne, S; Van Bokhoven, H; Candi, E; Melino, G; Aberdam, D

2011-01-01

p63, a member of p53 family, has a significant role in the development and maintenance of stratified epithelia. However, a persistent dispute remained over the last decade concerning the interpretation of the severe failure of p63-null embryos to develop stratified epithelia. In this study, by investigating both p63-deficient strains, we demonstrated that p63-deficient epithelia failed to develop beyond ectodermal stage as they remained a monolayer of non-proliferating cells expressing K8/K18. Importantly, in the absence of p63, corneal-epithelial commitment (which occurs at embryonic day 12.5 of mouse embryogenesis) was hampered 3 weeks before corneal stem cell renewal (that begins at P14). Taken together, these data illustrate the significant role of p63 in epithelial embryogenesis, before and independently of other functions of p63 in adult stem cells regulation. Transcriptome analysis of laser captured-embryonic tissues confirmed the latter hypothesis, demonstrating that a battery of epidermal genes that were activated in wild-type epidermis remained silent in p63-null tissues. Furthermore, we defined a subset of novel bona fide p63-induced genes orchestrating first epidermal stratification and a subset of p63-repressed mesodermal-specific genes. These data highlight the earliest recognized action of ΔNp63 in the induction epidermal morphogenesis at E11.5. In the absence of p63, a mesodermal program is activated while epidermal morphogenesis does not initiate. PMID:21127502

The role of lin-22, a hairy/enhancer of split homolog, in patterning the peripheral nervous system of C. elegans.

PubMed

Wrischnik, L A; Kenyon, C J

1997-08-01

In C. elegans, six lateral epidermal stem cells, the seam cells V1-V6, are located in a row along the anterior-posterior (A/P) body axis. Anterior seam cells (V1-V4) undergo a fairly simple sequence of stem cell divisions and generate only epidermal cells. Posterior seam cells (V5 and V6) undergo a more complicated sequence of cell divisions that include additional rounds of stem cell proliferation and the production of neural as well as epidermal cells. In the wild type, activity of the gene lin-22 allows V1-V4 to generate their normal epidermal lineages rather than V5-like lineages. lin-22 activity is also required to prevent additional neurons from being produced by one branch of the V5 lineage. We find that the lin-22 gene exhibits homology to the Drosophila gene hairy, and that lin-22 activity represses neural development within the V5 lineage by blocking expression of the posterior-specific Hox gene mab-5 in specific cells. In addition, in order to prevent anterior V cells from generating V5-like lineages, wild-type lin-22 gene activity must inhibit (directly or indirectly) at least five downstream regulatory gene activities. In anterior body regions, lin-22(+) inhibits expression of the Hox gene mab-5. It also inhibits the activity of the achaete-scute homolog lin-32 and an unidentified gene that we postulate regulates stem cell division. Each of these three genes is required for the expression of a different piece of the ectopic V5-like lineages generated in lin-22 mutants. In addition, lin-22 activity prevents two other Hox genes, lin-39 and egl-5, from acquiring new activities within their normal domains of function along the A/P body axis. Some, but not all, of the patterning activities of lin-22 in C. elegans resemble those of hairy in Drosophila.

Physical strain-mediated microtubule reorientation in the epidermis of gravitropically or phototropically stimulated maize coleoptiles.

PubMed

Fischer, K; Schopfer, P

1998-07-01

During gravitropic and phototropic curvature of the maize coleoptile, the cortical microtubules (MTs) adjacent to the outer epidermal cell wall assume opposite orientations at the two sides of the organ. Starting from a uniformly random pattern during straight growth in darkness, the MTs reorientate perpendicularly to the organ axis at the outer (faster growing) side and parallel to the organ axis at the inner (slower growing) side. As similar reorientations can be induced during straight growth by increasing or decreasing the effective auxin concentration, it has been proposed that these reorientations may be used as a diagnostic test for assessing the auxin status of the epidermal cells during tropic curvature. This idea was tested by determining the MT orientations in the coleoptile of intact maize seedlings in which the gravitropic or phototropic curvature was prevented or inversed by an appropriate mechanical counterforce. Forces that just prevented the coleoptile from curving in a gravity or light field prevented reorientations of the MTs. Forces strong enough to overcompensate the tropic stimuli by enforcing curvature in the opposite direction induced reorientations of the MTs opposite to those produced by tropic stimulation. These results show that the MTs at the outer surface of the coleoptile respond to changes in mechanical tissue strain rather than to gravitropic or phototropic stimuli and associated changes at the level of auxin or any other element in the signal transduction chain between perception of tropic stimuli and asymmetric growth response. It is proposed that cortical MTs can act as strain gauges in a positive feed-back regulatory circle utilized for amplification and stabilization of environmentally induced changes in the direction of elongation growth.

Cuticular lipid composition, surface structure, and gene expression in Arabidopsis stem epidermis.

PubMed

Suh, Mi Chung; Samuels, A Lacey; Jetter, Reinhard; Kunst, Ljerka; Pollard, Mike; Ohlrogge, John; Beisson, Fred

2005-12-01

All vascular plants are protected from the environment by a cuticle, a lipophilic layer synthesized by epidermal cells and composed of a cutin polymer matrix and waxes. The mechanism by which epidermal cells accumulate and assemble cuticle components in rapidly expanding organs is largely unknown. We have begun to address this question by analyzing the lipid compositional variance, the surface micromorphology, and the transcriptome of epidermal cells in elongating Arabidopsis (Arabidopsis thaliana) stems. The rate of cell elongation is maximal near the apical meristem and decreases steeply toward the middle of the stem, where it is 10 times slower. During and after this elongation, the cuticular wax load and composition remain remarkably constant (32 microg/cm2), indicating that the biosynthetic flux into waxes is closely matched to surface area expansion. By contrast, the load of polyester monomers per unit surface area decreases more than 2-fold from the upper (8 microg/cm2) to the lower (3 microg/cm2) portion of the stem, although the compositional variance is minor. To aid identification of proteins involved in the biosynthesis of waxes and cutin, we have isolated epidermal peels from Arabidopsis stems and determined transcript profiles in both rapidly expanding and nonexpanding cells. This transcriptome analysis was validated by the correct classification of known epidermis-specific genes. The 15% transcripts preferentially expressed in the epidermis were enriched in genes encoding proteins predicted to be membrane associated and involved in lipid metabolism. An analysis of the lipid-related subset is presented.

An evaluation of the choice of feeder cell growth arrest for the production of cultured epidermis.

PubMed

Chugh, Rishi Man; Chaturvedi, Madhusudan; Yerneni, Lakshmana Kumar

2015-12-01

Growth arrested 3T3 cells have been used as feeder cells in human epidermal keratinocyte cultures to produce cultured epidermal autografts for the treatment of burns. The feeder cells were ideally growth-arrested by gamma-irradiation. Alternatively, growth arrest by mitomycin C treatment is a cost effective option. We compared the functional efficacy of these two approaches in keratinocyte cultures by colony forming efficiency, the net growth area of colonies, BrdU labeling and histological features of cultured epidermal sheets. The growth area estimation involved a semi-automated digital technique using the Adobe Photoshop and comprised of isolation and enumeration of red pixels in Rhodamine B-stained keratinocyte colonies. A further refinement of the technique led to the identification of critical steps to increasing the degree of accuracy and enabling its application as an extension of colony formation assay. The results on feeder cell functionality revealed that the gamma irradiated feeders influenced significantly higher colony forming efficiency and larger growth area than the mitomycin C treated feeders. The BrdU labeling study indicated significant stimulation of the overall keratinocyte proliferation by the gamma irradiated feeders. The cultured epidermal sheets produced by gamma feeders were relatively thicker than those produced by mitomycin C feeders. We discussed the clinical utility of mitomycin C feeders from the viewpoint of cost-effective burn care in developing countries. Copyright © 2015 Elsevier Ltd and ISBI. All rights reserved.

Root hair development in grasses and cereals (Poaceae).

PubMed

Dolan, Liam

2017-08-01

Root hairs are tubular, cellular outgrowths of epidermal cells that extend from the root surface into the soil. Root hairs tether root systems to their growth substrate, take up inorganic nutrients and water, and interact with the soil microflora. At maturity, the root epidermis comprises two cell types; cells with root hairs and hairless epidermal cells. These two cell types alternate with each other along longitudinal files in grasses and cereals (Poaceae). While the mechanism by which this alternating pattern develops is unknown, the later stages of root hair differentiation are controlled by a conserved mechanism that promotes root hair development among angiosperms. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Staphylococcus aureus keratinocyte invasion is mediated by integrin-linked kinase and Rac1.

PubMed

Sayedyahossein, Samar; Xu, Stacey X; Rudkouskaya, Alena; McGavin, Martin J; McCormick, John K; Dagnino, Lina

2015-02-01

Staphylococcus aureus is a major component of the skin microbiota and causes a large number of serious infections. S. aureus first interacts with epidermal keratinocytes to breach the epidermal barrier through mechanisms not fully understood. By use of primary keratinocytes from mice with epidermis-restricted Ilk gene inactivation and control integrin-linked kinase (ILK)-expressing littermates, we investigated the role of ILK in epidermal S. aureus invasion. Heat-killed, but not live, bacteria were internalized to Rab5- and Rab7-positive phagosomes, and incubation with keratinocyte growth factor increased their uptake 2.5-fold. ILK-deficient mouse keratinocytes internalized bacteria 2- to 4-fold less efficiently than normal cells. The reduced invasion by live S. aureus of ILK-deficient cells was restored in the presence of exogenous, constitutively active Rac1. Thus, Rac1 functions downstream from ILK during invasion. Further, invasion by S. aureus of Rac1-deficient cells was 2.5-fold lower than in normal cells. Paradoxically, staphylococcal cutaneous penetration of mouse skin explants with ILK-deficient epidermis was 35-fold higher than that of normal skin, indicating defects in epidermal barrier function in the absence of ILK. Thus, we identified an ILK-Rac1 pathway essential for bacterial invasion of keratinocytes, and established ILK as a key contributor to prevent invasive staphylococcal cutaneous infection. © FASEB.

Morphological and transcript changes in the biosynthesis of lignin in oil palm (Elaeis guineensis) during Ganoderma boninense infections in vitro.

PubMed

Goh, Kar Mun; Dickinson, Matthew; Supramaniam, Christina V

2018-03-01

Lignification of the plant cell wall could serve as the first line of defense against pathogen attack, but the molecular mechanisms of virulence and disease between oil palm and Ganoderma boninense are poorly understood. This study presents the biochemical, histochemical, enzymology and gene expression evidences of enhanced lignin biosynthesis in young oil palm as a response to G. boninense (GBLS strain). Comparative studies with control (T1), wounded (T2) and infected (T3) oil palm plantlets showed significant accumulation of total lignin content and monolignol derivatives (syringaldehyde and vanillin). These derivatives were deposited on the epidermal cell wall of infected plants. Moreover, substantial differences were detected in the activities of enzyme and relative expressions of genes encoding phenylalanine ammonia lyase (EC 4.3.1.24), cinnamate 4-hydroxylase (EC 1.14.13.11), caffeic acid O-methyltransferase (EC 2.1.1.68) and cinnamyl alcohol dehydrogenase (CAD, EC 1.1.1.195). These enzymes are key intermediates dedicated to the biosynthesis of lignin monomers, the guaicyl (G), syringyl (S) and ρ-hydroxyphenyl (H) subunits. Results confirmed an early, biphasic and transient positive induction of all gene intermediates, except for CAD enzyme activities. These differences were visualized by anatomical and metabolic changes in the profile of lignin in the oil palm plantlets such as low G lignin, indicating a potential mechanism for enhanced susceptibility toward G. boninense infection. © 2017 Scandinavian Plant Physiology Society.

Diminished survival of human cytotrophoblast cells exposed to hypoxia/reoxygenation injury and associated reduction of heparin-binding epidermal growth factor-like growth factor.

PubMed

Leach, Richard E; Kilburn, Brian A; Petkova, Anelia; Romero, Roberto; Armant, D Randall

2008-04-01

The antiapoptotic action of heparin-binding epidermal growth factor (HBEGF)-like growth factor and its regulation by O(2) constitutes a key factor for trophoblast survival. The hypothesis that cytotrophoblast survival is compromised by exposure to hypoxia-reoxygenation (H/R) injury, which may contribute to preeclampsia and some missed abortions, prompted us to investigate HBEGF regulation and its role as a survival factor during H/R in cytotrophoblast cells. A transformed human first-trimester cytotrophoblast cell line HTR-8/SVneo was exposed to H/R (2% O(2) followed by 20% O(2)) and assessed for HBEGF expression and cell death. Cellular HBEGF declined significantly within 30 minutes of reoxygenation after culture at 2% O(2). H/R significantly reduced proliferation and increased cell death when compared with trophoblast cells cultured continuously at 2% or 20% O(2). Restoration of cell survival also was achieved by adding recombinant HBEGF during reoxygenation. HBEGF inhibited apoptosis through its binding to either human epidermal receptor (HER)-1 or HER4, its cognate receptors. These results provide evidence that cytotrophoblast exposure to H/R induces apoptosis and decreased cell proliferation. HBEGF accumulation is diminished under these conditions, whereas restoration of HBEGF signaling improves trophoblast survival.

Model of in vitro healing to test the influence of dedifferentiated Crithmum maritimum cells on dermal repair and epidermal regeneration.

PubMed

Lequeux, C; Lhoste, A; Rovere, M R; Montastier, C; Damour, O

2011-01-01

The aim was to test the influence of dedifferentiated Crithmum maritimum cells (dCMC), totipotent vegetal stem cells, on epidermal regeneration in perfect homeostasis using a skin equivalent (SE) model. SE are prepared by seeding fibroblasts on a collagen-glycosaminoglycan-chitosan dermal substrate (DS) epidermalized by keratinocytes 3 weeks later. The originality of this present study lies in the systemic administration of dCMC from the moment when fibroblasts are seeded in the DS right through to the reconstruction of the SE. The thickness of the epidermis as well as the number of proliferating cells expressing Ki-67 and layers expressing terminal differentiation marker (filaggrin) were compared in the dCMC-treated SE versus an untreated control group. dCMC accelerated the complete regeneration and differentiation of the epidermis compared to the negative control (35 days instead of 42 days). Histology showed a multilayered, thick and differentiated epithelium after 35 days of culture. The basal and suprabasal layers had increased 4.88 ± 0.41 times versus the negative control (Mann-Whitney U test: p < 0.001). This result was attributed to the greater proliferation of basal cells because the cell numbers expressing the Ki-67 proliferation marker had increased significantly compared to the negative control (Mann-Whitney U test: p < 0.001). Moreover, dCMC allowed the differentiated epithelium to recover because only treated SE expressed the terminal differentiation marker filaggrin. Our data show that dCMC enhance epidermal cell grafts by stimulating their regeneration and differentiation in perfect homeostasis. They allow the epidermis to recover its structure for protective functions faster than the negative control. Copyright © 2010 S. Karger AG, Basel.

Mitochondrial gene expression changes in cultured human skin cells following simulated sunlight irradiation.

PubMed

Kelly, J; Murphy, J E

2018-02-01

Exposure of skin to simulated sunlight irradiation (SSI) has being extensively researched and shown to be the main cause for changes in the skin including changes in cellular function and generation of reactive oxygen species (ROS). This oxidative stress can subsequently exert downstream effects and the subcellular compartments most affected by this oxidative stress are mitochondria. The importance of functional mitochondrial morphology is apparent as morphological defects are related to many human diseases including diabetes mellitus, liver disease, neurodegenerative diseases, aging and cancer. The main objective of this study was to evaluate solar radiation-induced changes in mitochondrial gene expression in human skin cells using a Q-Sun solar simulator to deliver a close match to the intensity of summer sunlight. Spontaneously immortalised human skin epidermal keratinocytes (HaCaT) and Human Dermal Fibroblasts (HDFn) were divided into two groups. Group A were irradiated once and Group B twice 7days apart; following irradiation, mitochondrial gene expression was evaluated 1, 4 and 7days post primary exposure for group A and 1, 4, 7 and 14days post-secondary exposure for group B. Both the epidermal and dermal cells displayed significant reduced expression of the genes analysed for mitochondrial morphology and function; however, epidermal cells displayed this reduction post SSI earlier then dermal cells at multiple time points. The data presented here reinforces the fact that epidermal cells, while displaying a heightened sensitivity to sunlight, are less prone to changes in gene expression, while dermal cells, which appear to be more resilient are possibly more prone to genomic instability and mitochondrial damage. Copyright © 2017 Elsevier B.V. All rights reserved.

New insights into desmosome regulation and pemphigus blistering as a desmosome-remodeling disease.

PubMed

Kitajima, Yasuo

2013-01-01

Desmosomes in keratinocytes are the most important intercellular adhering junctions that provide structural strength for the epidermis. These junctions are connected directly with desmosomal cadherin proteins. Desmosomal cadherins are divided into four desmogleins (Dsgs), Dsg1-4, and three desmocollins (Dscs), Dsc1-3, all of which are involved in desmosomal adhesion by homo- and/or heterophilic binding between Dsgs and Dscs in a Ca(2+)-dependent manner. Cadherins are present on the cell surface and anchor keratin intermediate filaments (KIFs) to their inner cytoplasmic surface to generate an intracellular KIF-skeletal scaffold through several associate proteins, including plakoglobin, plakophillin, and desmoplakins. As such, the desmosomal contacts between adjacent cells generate an intercellular KIF scaffold throughout the whole epidermal sheet. However, despite these critical roles in maintaining epidermal adhesion and integrity, desmosomes are not static structures. Rather, they are dynamic units that undergo regular remodeling, i.e., assembly and disassembly, to allow for cell migration within the epidermis in response to outside-in signaling during epidermal differentiation. Recently, two cell-cell adhesion states controlled by desmosomes have been recognized, including "stable hyperadhesion (Ca(2+)-independent)" and "dynamic weak-adhesion (Ca(2+)-dependent)" conditions. These conditions are mutually reversible through cell signaling events involving protein kinase C (PKC) and epidermal growth factor receptor. Pemphigus vulgaris (PV) is an autoimmune bullous disease caused by anti-Dsg3 antibodies. Binding of these antibodies to Dsg3 causes endocytosis of Dsg3 from the cell surface and results in the specific depletion of Dsg3 from desmosomes, an event linked to acantholysis in the epidermis. This binding of anti-Dsg3 antibody to Dsg3 in epidermal keratinocytes activates PKC, to generate the "weak-adhesion (Ca(2+)-dependent)" state of desmosomes. The weak-adhesion desmosomes appear to be the susceptible desmosomal state and a prerequisite for Dsg3 depletion from desmosomes, pivotal and specific events leading to PV blistering. These observations allow us to propose a concept for pemphigus blistering disorders as a "desmosome-remodeling impairment disease" involving a mechanism of Dsg3 nonassembly and depletion from desmosomes through PV immunoglobulin G-activated intracellular signaling events. Copyright © 2012. Published by Elsevier B.V.

Toxicity Assessment of Six Titanium Dioxide Nanoparticles in Human Epidermal Keratinocytes

EPA Science Inventory

Toxicity Assessment of Six Titanium Dioxide Nanoparticles in Human Epidermal Keratinocytes Nanoparticle uptake in cells may be an important determinant of their potential cytotoxic and inflammatory effects. Six commercial TiO2 NP (A=Alfa Aesar,10nm, A*=Alfa Aesar 32nm, B=P25 27...

The association of peroxisomes with the developing cell plate in dividing onion root cells depends on actin microfilaments and myosin.

PubMed

Collings, David A; Harper, John D I; Vaughn, Kevin C

2003-12-01

We have investigated changes in the distribution of peroxisomes through the cell cycle in onion ( Allium cepa L.) root meristem cells with immunofluorescence and electron microscopy, and in leek ( Allium porrum L.) epidermal cells with immunofluorescence and peroxisomal-targeted green fluorescent protein. During interphase and mitosis, peroxisomes distribute randomly throughout the cytoplasm, but beginning late in anaphase, they accumulate at the division plane. Initially, peroxisomes occur within the microtubule phragmoplast in two zones on either side of the developing cell plate. However, as the phragmoplast expands outwards to form an annulus, peroxisomes redistribute into a ring immediately inside the location of the microtubules. Peroxisome aggregation depends on actin microfilaments and myosin. Peroxisomes first accumulate in the division plane prior to the formation of the microtubule phragmoplast, and throughout cytokinesis, always co-localise with microfilaments. Microfilament-disrupting drugs (cytochalasin and latrunculin), and a putative inhibitor of myosin (2,3-butanedione monoxime), inhibit aggregation. We propose that aggregated peroxisomes function in the formation of the cell plate, either by regulating hydrogen peroxide production within the developing cell plate, or by their involvement in recycling of excess membranes from secretory vesicles via the beta-oxidation pathway. Differences in aggregation, a phenomenon which occurs in onion, some other monocots and to a lesser extent in tobacco BY-2 suspension cells, but which is not obvious in the roots of Arabidopsis thaliana (L.) Heynh., may reflect differences within the primary cell walls of these plants.

The control of epidermal stem cells (holoclones) in the treatment of massive full-thickness burns with autologous keratinocytes cultured on fibrin.

PubMed

Pellegrini, G; Ranno, R; Stracuzzi, G; Bondanza, S; Guerra, L; Zambruno, G; Micali, G; De Luca, M

1999-09-27

Cell therapy is an emerging therapeutic strategy aimed at replacing or repairing severely damaged tissues with cultured cells. Epidermal regeneration obtained with autologous cultured keratinocytes (cultured autografts) can be life-saving for patients suffering from massive full-thickness burns. However, the widespread use of cultured autografts has been hampered by poor clinical results that have been consistently reported by different burn units, even when cells were applied on properly prepared wound beds. This might arise from the depletion of epidermal stem cells (holoclones) in culture. Depletion of holoclones can occur because of (i) incorrect culture conditions, (ii) environmental damage of the exposed basal layer of cultured grafts, or (iii) use of new substrates or culture technologies not pretested for holoclone preservation. The aim of this study was to show that, if new keratinocyte culture technologies and/or "delivery systems" are proposed, a careful evaluation of epidermal stem cell preservation is essential for the clinical performance of this life-saving technology. Fibrin was chosen as a potential substrate for keratinocyte cultivation. Stem cells were monitored by clonal analysis using the culture system originally described by Rheinwald and Green as a reference. Massive full-thickness burns were treated with the composite allodermis/cultured autograft technique. We show that: (i) the relative percentage of holoclones, meroclones, and paraclones is maintained when keratinocytes are cultivated on fibrin, proving that fibrin does not induce clonal conversion and consequent loss of epidermal stem cells; (ii) the clonogenic ability, growth rate, and long-term proliferative potential are not affected by the new culture system; (iii) when fibrin-cultured autografts bearing stem cells are applied on massive full-thickness burns, the "take" of keratinocytes is high, reproducible, and permanent; and (iv) fibrin allows a significant reduction of the cost of cultured autografts and eliminates problems related to their handling and transportation. Our data demonstrate that: (i) cultured autografts bearing stem cells can indeed rapidly and permanently cover a large body surface; and (ii) fibrin is a suitable substrate for keratinocyte cultivation and transplantation. These data lend strength to the concept that the success of cell therapy at a clinical level requires cultivation and transplantation of stem cells. We therefore suggest that the proposal of a culture system aimed at the replacement of any severely damaged self-renewing tissue should be preceded by a careful evaluation of its stem cell population.

Single-cell gene expression profiling reveals functional heterogeneity of undifferentiated human epidermal cells

PubMed Central

Tan, David W. M.; Jensen, Kim B.; Trotter, Matthew W. B.; Connelly, John T.; Broad, Simon; Watt, Fiona M.

2013-01-01

Human epidermal stem cells express high levels of β1 integrins, delta-like 1 (DLL1) and the EGFR antagonist LRIG1. However, there is cell-to-cell variation in the relative abundance of DLL1 and LRIG1 mRNA transcripts. Single-cell global gene expression profiling showed that undifferentiated cells fell into two clusters delineated by expression of DLL1 and its binding partner syntenin. The DLL1+ cluster had elevated expression of genes associated with endocytosis, integrin-mediated adhesion and receptor tyrosine kinase signalling. Differentially expressed genes were not independently regulated, as overexpression of DLL1 alone or together with LRIG1 led to the upregulation of other genes in the DLL1+ cluster. Overexpression of DLL1 and LRIG1 resulted in enhanced extracellular matrix adhesion and increased caveolin-dependent EGFR endocytosis. Further characterisation of CD46, one of the genes upregulated in the DLL1+ cluster, revealed it to be a novel cell surface marker of human epidermal stem cells. Cells with high endogenous levels of CD46 expressed high levels of β1 integrin and DLL1 and were highly adhesive and clonogenic. Knockdown of CD46 decreased proliferative potential and β1 integrin-mediated adhesion. Thus, the previously unknown heterogeneity revealed by our studies results in differences in the interaction of undifferentiated basal keratinocytes with their environment. PMID:23482486

A mitosis block links active cell cycle with human epidermal differentiation and results in endoreplication.

PubMed

Zanet, Jennifer; Freije, Ana; Ruiz, María; Coulon, Vincent; Sanz, J Ramón; Chiesa, Jean; Gandarillas, Alberto

2010-12-20

How human self-renewal tissues co-ordinate proliferation with differentiation is unclear. Human epidermis undergoes continuous cell growth and differentiation and is permanently exposed to mutagenic hazard. Keratinocytes are thought to arrest cell growth and cell cycle prior to terminal differentiation. However, a growing body of evidence does not satisfy this model. For instance, it does not explain how skin maintains tissue structure in hyperproliferative benign lesions. We have developed and applied novel cell cycle techniques to human skin in situ and determined the dynamics of key cell cycle regulators of DNA replication or mitosis, such as cyclins E, A and B, or members of the anaphase promoting complex pathway: cdc14A, Ndc80/Hec1 and Aurora kinase B. The results show that actively cycling keratinocytes initiate terminal differentiation, arrest in mitosis, continue DNA replication in a special G2/M state, and become polyploid by mitotic slippage. They unambiguously demonstrate that cell cycle progression coexists with terminal differentiation, thus explaining how differentiating cells increase in size. Epidermal differentiating cells arrest in mitosis and a genotoxic-induced mitosis block rapidly pushes epidermal basal cells into differentiation and polyploidy. These observations unravel a novel mitosis-differentiation link that provides new insight into skin homeostasis and cancer. It might constitute a self-defence mechanism against oncogenic alterations such as Myc deregulation.

A Mitosis Block Links Active Cell Cycle with Human Epidermal Differentiation and Results in Endoreplication

PubMed Central

Zanet, Jennifer; Freije, Ana; Ruiz, María; Coulon, Vincent; Sanz, J. Ramón; Chiesa, Jean; Gandarillas, Alberto

2010-01-01

How human self-renewal tissues co-ordinate proliferation with differentiation is unclear. Human epidermis undergoes continuous cell growth and differentiation and is permanently exposed to mutagenic hazard. Keratinocytes are thought to arrest cell growth and cell cycle prior to terminal differentiation. However, a growing body of evidence does not satisfy this model. For instance, it does not explain how skin maintains tissue structure in hyperproliferative benign lesions. We have developed and applied novel cell cycle techniques to human skin in situ and determined the dynamics of key cell cycle regulators of DNA replication or mitosis, such as cyclins E, A and B, or members of the anaphase promoting complex pathway: cdc14A, Ndc80/Hec1 and Aurora kinase B. The results show that actively cycling keratinocytes initiate terminal differentiation, arrest in mitosis, continue DNA replication in a special G2/M state, and become polyploid by mitotic slippage. They unambiguously demonstrate that cell cycle progression coexists with terminal differentiation, thus explaining how differentiating cells increase in size. Epidermal differentiating cells arrest in mitosis and a genotoxic-induced mitosis block rapidly pushes epidermal basal cells into differentiation and polyploidy. These observations unravel a novel mitosis-differentiation link that provides new insight into skin homeostasis and cancer. It might constitute a self-defence mechanism against oncogenic alterations such as Myc deregulation. PMID:21187932

Considerations in the improvement of human epidermal keratinocyte culture in vitro.

PubMed

Kaviani, Maryam; Geramizadeh, Bita; Rahsaz, Marjan; Marzban, Saeed

2015-04-01

Large-scale expansion of epidermal keratinocytes is essential in the application of these cells for severe burn treatment in patients. Therefore, this study was designed to evaluate various conditions in the expansion of human epidermal keratinocytes. The epidermis was separated from the dermis of skin samples using dispase. The epidermis was trypsinized for keratinocyte isolation. Keratinocytes were cultured in various conditions, with or without a human dermal fibroblast feeder layer, mitomycin C treatment, and different culture media. Our results suggest that keratinocytes cultured on a human dermal fibroblast feeder layer were grown for several passages. Extensive deformation and rapid deterioration were observed in the cultured cells without a feeder layer and in serum-free medium. Human dermal fibroblasts treated with mitomycin C can provide optimal conditions for proliferation of keratinocytes.

Cell motion predicts human epidermal stemness

PubMed Central

Toki, Fujio; Tate, Sota; Imai, Matome; Matsushita, Natsuki; Shiraishi, Ken; Sayama, Koji; Toki, Hiroshi; Higashiyama, Shigeki

2015-01-01

Image-based identification of cultured stem cells and noninvasive evaluation of their proliferative capacity advance cell therapy and stem cell research. Here we demonstrate that human keratinocyte stem cells can be identified in situ by analyzing cell motion during their cultivation. Modeling experiments suggested that the clonal type of cultured human clonogenic keratinocytes can be efficiently determined by analysis of early cell movement. Image analysis experiments demonstrated that keratinocyte stem cells indeed display a unique rotational movement that can be identified as early as the two-cell stage colony. We also demonstrate that α6 integrin is required for both rotational and collective cell motion. Our experiments provide, for the first time, strong evidence that cell motion and epidermal stemness are linked. We conclude that early identification of human keratinocyte stem cells by image analysis of cell movement is a valid parameter for quality control of cultured keratinocytes for transplantation. PMID:25897083

Genome-wide identification of multifunctional laccase gene family in cotton (Gossypium spp.); expression and biochemical analysis during fiber development

PubMed Central

Balasubramanian, Vimal Kumar; Rai, Krishan Mohan; Thu, Sandi Win; Hii, Mei Mei; Mendu, Venugopal

2016-01-01

The single-celled cotton fibers, produced from seed coat epidermal cells are the largest natural source of textile fibers. The economic value of cotton fiber lies in its length and quality. The multifunctional laccase enzymes play important roles in cell elongation, lignification and pigmentation in plants and could play crucial role in cotton fiber quality. Genome-wide analysis of cultivated allotetraploid (G. hirsutum) and its progenitor diploid (G. arboreum and G. raimondii) cotton species identified 84, 44 and 46 laccase genes, respectively. Analysis of chromosomal location, phylogeny, conserved domain and physical properties showed highly conserved nature of laccases across three cotton species. Gene expression, enzymatic activity and biochemical analysis of developing cotton fibers was performed using G. arboreum species. Of the total 44, 40 laccases showed expression during different stages of fiber development. The higher enzymatic activity of laccases correlated with higher lignin content at 25 DPA (Days Post Anthesis). Further, analysis of cotton fiber phenolic compounds showed an overall decrease at 25 DPA indicating possible incorporation of these substrates into lignin polymer during secondary cell wall biosynthesis. Overall data indicate significant roles of laccases in cotton fiber development, and presents an excellent opportunity for manipulation of fiber development and quality. PMID:27679939

Remodelling of three-dimensional organization of the nucleus during terminal keratinocyte differentiation in the epidermis

PubMed Central

Gdula, Michal R.; Poterlowicz, Krzysztof; Mardaryev, Andrei N.; Sharov, Andrey A.; Peng, Y.; Fessing, Michael Y.; Botchkarev, Vladimir A.

2014-01-01

The nucleus of epidermal keratinocytes is a complex and highly compartmentalized organelle, whose structure is markedly changed during terminal differentiation and transition of the genome from a transcriptionally active state seen in the basal and spinous epidermal cells to a fully inactive state in the keratinized cells of the cornified layer. Here, using multi-color confocal microscopy, followed by computational image analysis and mathematical modelling, we demonstrate that in normal mouse foot-pad epidermis transition of keratinocytes from basal epidermal layer to the granular layer is accompanied by marked differences in nuclear architecture and micro-environment including: i) decrease of the nuclear volume, ii) decrease in expression of the markers of transcriptionally-active chromatin; iii) internalization and decrease in the number of nucleoli; iv) increase in the number of pericentromeric heterochromatic clusters; v) increase in the frequency of associations between pericentromeric clusters, chromosomal territory 3, and nucleoli. These data suggest a role for nucleoli and pericentromeric heterochromatin clusters as organizers of nuclear micro-environment required for proper execution of gene expression programs in differentiating keratinocytes and provide important background information for further analyses of alterations in the topological genome organization seen in pathological skin conditions including disorders of epidermal differentiation and epidermal tumors. PMID:23407401

Modified methods for growing 3-D skin equivalents: an update.

PubMed

Lamb, Rebecca; Ambler, Carrie A

2014-01-01

Artificial epidermis can be reconstituted in vitro by seeding primary epidermal cells (keratinocytes) onto a supportive substrate and then growing the developing skin equivalent at the air-liquid interface. In vitro skin models are widely used to study skin biology and for industrial drug and cosmetic testing. Here, we describe updated methods for growing 3-dimensional skin equivalents using de-vitalized, de-epidermalized dermis (DED) substrates including methods for DED substrate preparation, cell seeding, growth conditions, and fixation procedures.

[On the nervous system of a parasitic cnidarian Polypodium hydriforme].

PubMed

Raĭkova, E V

2013-01-01

Nerve cells in a parasitic cnidarian Polypodium hydriforme at the parasitic and free-living stages of the life cycle have been localized immunocytochemically using antibodies to FMRF-amide, and their ultrastructure has been described. Ganglion cells form a net under epidermis consisting of bi- and tripolar neurons which cross the mesoglea and usually contact muscle cells and cnidocytes. Fusiform sensory and neurosecretory cells, especially characteristic to sensory tentacles, are interspersed among epidermal cells. All three types of nerve cells have dense cored vesicles about 80-120 nm in diameter. The sensory cells demonstrate a sensory flagellum-like immobile structure. Neurosecretory and sensory cells form septate junctions with epidermal cells. Ganglion cells show gap junctions between them. A centriole encircled by a fragment of nuclear envelope which is a marker of ectodermal lineage cells in Polypodium has been described in the cytoplasm of a sensory cell, thus proving the ectodermal nature of the nervous system.

Emodin suppresses maintenance of stemness by augmenting proteosomal degradation of epidermal growth factor receptor/epidermal growth factor receptor variant III in glioma stem cells.

PubMed

Kim, Jeongyub; Lee, Jong-Seon; Jung, Jieun; Lim, Inhye; Lee, Ji-Yun; Park, Myung-Jin

2015-02-01

There is a growing body of evidence that small subpopulations of cells with stem cell-like characteristics within most solid tumors are responsible for the malignancy of aggressive cancer cells and that targeting these cells might be a good therapeutic strategy to reduce the risk of tumor relapse after therapy. Here, we examined the effects of emodin (1,3,8-trihydroxy-6-methylanthraquinone), an active component of the root and rhizome of Rheum palmatum that has several biological activities, including antitumor effects, on primary cultured glioma stem cells (GSCs). Emodin inhibited the self-renewal activity of GSCs in vitro as evidenced by neurosphere formation, limiting dilution, and soft agar clonogenic assays. Emodin inhibited the maintenance of stemness by suppressing the expression of Notch intracellular domain, nonphosphorylated β-catenin, and phosphorylated STAT3 proteins. In addition, treatment with emodin partially induced apoptosis, reduced cell invasiveness, and sensitized GSCs to ionizing radiation. Intriguingly, emodin induced proteosomal degradation of epidermal growth factor receptor (EGFR)/EGFR variant III (EGFRvIII) by interfering with the association of EGFR/EGFRvIII with heat shock protein 90, resulting in the suppression of stemness pathways. Based on these data, we propose that emodin could be considered as a potent therapeutic adjuvant that targets GSCs.

Analysis of Cell Division and Elongation Underlying the Developmental Acceleration of Root Growth in Arabidopsis thaliana1

PubMed Central

Beemster, Gerrit T.S.; Baskin, Tobias I.

1998-01-01

To investigate the relation between cell division and expansion in the regulation of organ growth rate, we used Arabidopsis thaliana primary roots grown vertically at 20°C with an elongation rate that increased steadily during the first 14 d after germination. We measured spatial profiles of longitudinal velocity and cell length and calculated parameters of cell expansion and division, including rates of local cell production (cells mm−1 h−1) and cell division (cells cell−1 h−1). Data were obtained for the root cortex and also for the two types of epidermal cell, trichoblasts and atrichoblasts. Accelerating root elongation was caused by an increasingly longer growth zone, while maximal strain rates remained unchanged. The enlargement of the growth zone and, hence, the accelerating root elongation rate, were accompanied by a nearly proportionally increased cell production. This increased production was caused by increasingly numerous dividing cells, whereas their rates of division remained approximately constant. Additionally, the spatial profile of cell division rate was essentially constant. The meristem was longer than generally assumed, extending well into the region where cells elongated rapidly. In the two epidermal cell types, meristem length and cell division rate were both very similar to that of cortical cells, and differences in cell length between the two epidermal cell types originated at the apex of the meristem. These results highlight the importance of controlling the number of dividing cells, both to generate tissues with different cell lengths and to regulate the rate of organ enlargement. PMID:9536070

Comparative SEM and LM foliar epidermal and palyno-morphological studies of Amaranthaceae and its taxonomic implications.

PubMed

Hussain, Amara Noor; Zafar, Muhammad; Ahmad, Mushtaq; Khan, Raees; Yaseen, Ghulam; Khan, Muhammad Saleem; Nazir, Abdul; Khan, Amir Muhammad; Shaheen, Shabnum

2018-05-01

Palynological features as well as comparative foliar epidermal using light and scanning electron microscope (SEM) of 17 species (10genera) of Amaranthaceae have been studied for its taxonomic significance. Different foliar and palynological micro-morphological characters were examined to explain their value in resolving the difficulty in identification. All species were amphistomatic but stomata on abaxial surface were more abundant. Taxonomically significant epidermal character including stomata type, trichomes (unicellular, multicellular, and capitate) and epidermal cells shapes (polygonal and irregular) were also observed. Pollens of this family are Polypantoporate, pores large, spheroidal, mesoporous region is sparsely to scabrate, densely psilate, and spinulose. All these characters can be active at species level for identification purpose. This study indicates that at different taxonomic levels, LM and SEM pollen and epidermal morphology is explanatory and significant to identify species and genera. © 2018 Wiley Periodicals, Inc.

The homeoprotein DLX3 and tumor suppressor p53 co-regulate cell cycle progression and squamous tumor growth.

PubMed

Palazzo, E; Kellett, M; Cataisson, C; Gormley, A; Bible, P W; Pietroni, V; Radoja, N; Hwang, J; Blumenberg, M; Yuspa, S H; Morasso, M I

2016-06-16

Epidermal homeostasis depends on the coordinated control of keratinocyte cell cycle. Differentiation and the alteration of this balance can result in neoplastic development. Here we report on a novel DLX3-dependent network that constrains epidermal hyperplasia and squamous tumorigenesis. By integrating genetic and transcriptomic approaches, we demonstrate that DLX3 operates through a p53-regulated network. DLX3 and p53 physically interact on the p21 promoter to enhance p21 expression. Elevating DLX3 in keratinocytes produces a G1-S blockade associated with p53 signature transcriptional profiles. In contrast, DLX3 loss promotes a mitogenic phenotype associated with constitutive activation of ERK. DLX3 expression is lost in human skin cancers and is extinguished during progression of experimentally induced mouse squamous cell carcinoma (SCC). Reinstatement of DLX3 function is sufficient to attenuate the migration of SCC cells, leading to decreased wound closure. Our data establish the DLX3-p53 interplay as a major regulatory axis in epidermal differentiation and suggest that DLX3 is a modulator of skin carcinogenesis.

Cdc42 regulates junctional actin but not cell polarization in the Caenorhabditis elegans epidermis

PubMed Central

Zilberman, Yuliya; Abrams, Joshua; Anderson, Dorian C.

2017-01-01

During morphogenesis, adherens junctions (AJs) remodel to allow changes in cell shape and position while preserving adhesion. Here, we examine the function of Rho guanosine triphosphatase CDC-42 in AJ formation and regulation during Caenorhabditis elegans embryo elongation, a process driven by asymmetric epidermal cell shape changes. cdc-42 mutant embryos arrest during elongation with epidermal ruptures. Unexpectedly, we find using time-lapse fluorescence imaging that cdc-42 is not required for epidermal cell polarization or junction assembly, but rather is needed for proper junctional actin regulation during elongation. We show that the RhoGAP PAC-1/ARHGAP21 inhibits CDC-42 activity at AJs, and loss of PAC-1 or the interacting linker protein PICC-1/CCDC85A-C blocks elongation in embryos with compromised AJ function. pac-1 embryos exhibit dynamic accumulations of junctional F-actin and an increase in AJ protein levels. Our findings identify a previously unrecognized molecular mechanism for inhibiting junctional CDC-42 to control actin organization and AJ protein levels during epithelial morphogenesis. PMID:28903999

The homeoprotein DLX3 and tumor suppressor p53 co-regulate cell cycle progression and squamous tumor growth

PubMed Central

Palazzo, Elisabetta; Kellett, Meghan; Cataisson, Christophe; Gormley, Anna; Bible, Paul W.; Pietroni, Valentina; Radoja, Nadezda; Hwang, Joonsung; Blumenberg, Miroslav; Yuspa, Stuart H.; Morasso, Maria

2015-01-01

Epidermal homeostasis depends on the coordinated control of keratinocyte cell cycle. Differentiation and the alteration of this balance can result in neoplastic development. Here we report on a novel DLX3-dependent network that constrains epidermal hyperplasia and squamous tumorigenesis. By integrating genetic and transcriptomic approaches, we demonstrate that DLX3 operates through a p53-regulated network. DLX3 and p53 physically interact on the p21 promoter to enhance p21 expression. Elevating DLX3 in keratinocytes produces a G1-S blockade associated with p53 signature transcriptional profiles. In contrast, DLX3 loss promotes a mitogenic phenotype associated with constitutive activation of ERK. DLX3 expression is lost in human skin cancers and is extinquished during progression of experimentally induced mouse squamous cell carcinoma (SCC). Reinstatement of DLX3 function is sufficient to attenuate the migration of SCC cells, leading to decreased wound closure. Our data establish the DLX3-p53 interplay as a major regulatory axis in epidermal differentiation and suggest that DLX3 is a modulator of skin carcinogenesis. PMID:26522723

H{sup +}/peptide transporter (PEPT2) is expressed in human epidermal keratinocytes and is involved in skin oligopeptide transport

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kudo, Michiko; Katayoshi, Takeshi; Kobayashi-Nakamura, Kumiko

Peptide transporter 2 (PEPT2) is a member of the proton-coupled oligopeptide transporter family, which mediates the cellular uptake of oligopeptides and peptide-like drugs. Although PEPT2 is expressed in many tissues, its expression in epidermal keratinocytes remains unclear. We investigated PEPT2 expression profile and functional activity in keratinocytes. We confirmed PEPT2 mRNA expression in three keratinocyte lines (normal human epidermal keratinocytes (NHEKs), immortalized keratinocytes, and malignant keratinocytes) by reverse transcription-polymerase chain reaction (RT-PCR) and quantitative real-time RT-PCR. In contrast to PEPT1, PEPT2 expression in the three keratinocytes was similar or higher than that in HepG2 cells, used as PEPT2-positive cells. Immunolocalizationmore » analysis using human skin showed epidermal PEPT2 localization. We studied keratinocyte transport function by measuring the oligopeptide content using liquid chromatography/tandem mass spectrometry. Glycylsarcosine uptake in NHEKs was pH-dependent, suggesting that keratinocytes could absorb small peptides in the presence of an inward H{sup +} gradient. We also performed a skin-permeability test of several oligopeptides using skin substitute, suggesting that di- and tripeptides pass actively through the epidermis. In conclusion, PEPT2 is expressed in keratinocytes and involved in skin oligopeptide uptake. -- Highlights: •PEPT2 is expressed in keratinocytes, which are more common than other skin cells. •Immunolocalization analysis using human skin revealed epidermal PEPT2 localization. •Keratinocytes could absorb small peptides in the presence of an inward H{sup +} gradient. •Di- and tripeptide pass actively through the epidermis.« less

Wall extensibility and gravitropic curvature of sunflower hypocotyls: correlation between timing of curvature and changes in extensibility

NASA Technical Reports Server (NTRS)

Bagshaw, S. L.; Cleland, R. E.

1990-01-01

Gravitropic curvature results from unequal growth rates on the upper and lower sides of horizontal stems. These unequal growth rates could be due to differences in wall extensibility between the two sides. To test this, the time course of curvature of horizontal sunflower (Helianthus annuus L.) hypocotyls was determined and compared with the time courses of changes in Instron-measured wall extensibility (PEx) of the upper and lower epidermal layers. As gravicurvature developed, so did the difference in PEx between the upper and lower epidermis. The enhanced growth rate on the lower side during the period of maximum increase in curvature was matched by PEx values greater than those of the vertical control, while the inhibited growth rate on the upper side was accompanied by PEx values below that of the control. The close correlation between changes in growth rates and alterations in PEx demonstrates that changes in wall extensibility play a major role in controlling gravicurvature.

Investigation of the effects of cadmium by micro analytical methods on Lycopersicon esculentum Mill. roots.

PubMed

Colak, G; Baykul, M C; Gürler, R; Catak, E; Caner, N

2014-09-01

The interactions between cadmium stress and plant nutritional elements have been investigated on complete plant or at the level of organs. This study was undertaken to contribute to the exploration of the physiological basis of cadmium phytotoxicity. We examined the changes in the nutritional element compositions of the root epidermal cells of the seedlings of Lycopersicon esculentum Mill. at the initial growth stages that is known as the most sensitive stage to the stress. Effects of cadmium stress on the seedlings of Lycopersicon esculentum Mill. were examined by EDX (Energy Dispersive X-Ray Microanalysis) assay performed with using low vacuum (∼ 24 Pascal) Scanning Electron Microscopy. In the analysis performed at the level of root epidermal cells, some of the macro- and micronutrient contents of the cells (carbon, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, copper, and zinc levels) were found to change when the applying toxic concentrations of cadmium. There was no change in the manganese and sodium content of the epidermal cells. It was concluded that the changes in nutritional element composition of the cells can be considered as an effective parameter in explaining the physiological mechanisms of cadmium-induced growth inhibition.

Optical sectioning and 3D reconstructions as an alternative to scanning electron microscopy for analysis of cell shape.

PubMed

Landis, Jacob B; Ventura, Kayla L; Soltis, Douglas E; Soltis, Pamela S; Oppenheimer, David G

2015-04-01

Visualizing flower epidermal cells is often desirable for investigating the interaction between flowers and their pollinators, in addition to the broader range of ecological interactions in which flowers are involved. We developed a protocol for visualizing petal epidermal cells without the limitations of the commonly used method of scanning electron microscopy (SEM). Flower material was collected and fixed in glutaraldehyde, followed by dehydration in an ethanol series. Flowers were dissected to collect petals, and subjected to a Histo-Clear series to remove the cuticle. Material was then stained with aniline blue, mounted on microscope slides, and imaged using a compound fluorescence microscope to obtain optical sections that were reconstructed into a 3D image. This optical sectioning method yielded high-quality images of the petal epidermal cells with virtually no damage to cells. Flowers were processed in larger batches than are possible using common SEM methods. Also, flower size was not a limiting factor as often observed in SEM studies. Flowers up to 5 cm in length were processed and mounted for visualization. This method requires no special equipment for sample preparation prior to imaging and should be seen as an alternative method to SEM.

Inhibiting the Epidermal Growth Factor Receptor | Center for Cancer Research

Cancer.gov

The Epidermal Growth Factor Receptor (EGFR) is a widely distributed cell surface receptor that responds to several extracellular signaling molecules through an intracellular tyrosine kinase, which phosphorylates target enzymes to trigger a downstream molecular cascade. Since the discovery that EGFR mutations and amplifications are critical in a number of cancers, efforts have

Epidermal barrier defects link atopic dermatitis with altered skin cancer susceptibility.

PubMed

Cipolat, Sara; Hoste, Esther; Natsuga, Ken; Quist, Sven R; Watt, Fiona M

2014-05-05

Atopic dermatitis can result from loss of structural proteins in the outermost epidermal layers, leading to a defective epidermal barrier. To test whether this influences tumour formation, we chemically induced tumours in EPI-/- mice, which lack three barrier proteins-Envoplakin, Periplakin, and Involucrin. EPI-/- mice were highly resistant to developing benign tumours when treated with 7,12-dimethylbenz(a)anthracene (DMBA) and 12-O-tetradecanoylphorbol-13-acetate (TPA). The DMBA response was normal, but EPI-/- skin exhibited an exaggerated atopic response to TPA, characterised by abnormal epidermal differentiation, a complex immune infiltrate and elevated serum thymic stromal lymphopoietin (TSLP). The exacerbated TPA response could be normalised by blocking TSLP or the immunoreceptor NKG2D but not CD4+ T cells. We conclude that atopy is protective against skin cancer in our experimental model and that the mechanism involves keratinocytes communicating with cells of the immune system via signalling elements that normally protect against environmental assaults.DOI: http://dx.doi.org/10.7554/eLife.01888.001. Copyright © 2014, Cipolat et al.

Endothelial network formed with human dermal microvascular endothelial cells in autologous multicellular skin substitutes.

PubMed

Ponec, Maria; El Ghalbzouri, Abdoelwaheb; Dijkman, Remco; Kempenaar, Johanna; van der Pluijm, Gabri; Koolwijk, Pieter

2004-01-01

A human skin equivalent from a single skin biopsy harboring keratinocytes and melanocytes in the epidermal compartment, and fibroblasts and microvascular dermal endothelial cells in the dermal compartment was developed. The results of the study revealed that the nature of the extracellular matrix of the dermal compartments plays an important role in establishment of endothelial network in vitro. With rat-tail type I collagen matrices only lateral but not vertical expansion of endothelial networks was observed. In contrast, the presence of extracellular matrix of entirely human origin facilitated proper spatial organization of the endothelial network. Namely, when human dermal fibroblasts and microvascular endothelial cells were seeded on the bottom of an inert filter and subsequently epidermal cells were seeded on top of it, fibroblasts produced extracellular matrix throughout which numerous branched tubes were spreading three-dimensionally. Fibroblasts also facilitated the formation of basement membrane at the epidermal/matrix interface. Under all culture conditions, fully differentiated epidermis was formed with numerous melanocytes present in the basal epidermal cell layer. The results of the competitive RT-PCR revealed that both keratinocytes and fibroblasts expressed VEGF-A, -B, -C, aFGF and bFGF mRNA, whereas fibroblasts also expressed VEGF-D mRNA. At protein level, keratinocytes produced 10 times higher amounts of VEGF-A than fibroblasts did. The generation of multicellular skin equivalent from a single human skin biopsy will stimulate further developments for its application in the treatment of full-thickness skin defects. The potential development of biodegradable, biocompatible material suitable for these purposes is a great challenge for future research.

VqDUF642, a gene isolated from the Chinese grape Vitis quinquangularis, is involved in berry development and pathogen resistance.

PubMed

Xie, Xiaoqing; Wang, Yuejin

2016-11-01

The DUF642 gene VqDUF642 , isolated from the Chinese grape species V. quinquangularis accession Danfeng-2, participates in berry development and defense responses against Erysiphe necator and Botrytis cinerea. The proteins with domains of unknown function 642 (DUF642) comprise a large protein family according to cell wall proteomic analyses in plants. However, the works about functional characterization of DUF642s in plant development and resistance to pathogens are scarce. In this study, a gene encoding a DUF642 protein was isolated from Chinese grape V. quinquangularis accession Danfeng-2, and designated as VqDUF642. Its full-length cDNA contains a 1107-bp open reading frame corresponding to a deduced 368-amino acid protein. Multiple sequence alignments and phylogenetic analysis showed that VqDUF642 is highly homologous to one of the DUF642 proteins (VvDUF642) in V. vinifera. The VqDUF642 was localized to the cell wall of tobacco epidermal cells. Accumulation of VqDUF642 protein and VqDUF642 transcript abundance increased at the later stage of grape berry development in Danfeng-2. Overexpression of VqDUF642 in transgenic tomato plants accelerated plant growth and reduced susceptibility to Botrytis cinerea. Transgenic Thompson Seedless grapevine plants overexpressing VqDUF642 exhibited enhanced resistance to Erysiphe necator and B. cinerea. Moreover, VqDUF642 overexpression affected the expression of a couple of pathogenesis-related (PR) genes in transgenic tomato and grapevine upon pathogen inoculation. Taken together, these results suggest that VqDUF642 is involved in plant development and defense against pathogenic infections.

Waterproofing in Arabidopsis: Following phenolics and lipids in situ by Confocal Raman Microscopy

NASA Astrophysics Data System (ADS)

Prats Mateu, Batirtze; Hauser, Marie-Theres; Heredia, Antonio; Gierlinger, Notburga

2016-02-01

Waterproofing of the aerial organs of plants imposed a big evolutionary step during the colonization of the terrestrial environment. The main plant polymers responsible of water repelling are lipids and lignin, which play also important roles in the protection against biotic/abiotic stresses, regulation of flux of gases and solutes and mechanical stability against negative pressure, among others. While the lipids, non-polymerized cuticular waxes together with the polymerized cutin, protect the outer surface, lignin is confined to the secondary cell wall within mechanical important tissues. In the present work a micro cross-section of the stem of Arabidopsis thaliana was used to track in situ the distribution of these non-carbohydrate polymers by Confocal Raman Microscopy. Raman hyperspectral imaging gives a molecular fingerprint of the native waterproofing tissues and cells with diffraction limited spatial resolution (~300 nm) at relatively high speed and without any tedious sample preparation. Lipids and lignified tissues as well as their effect on water content was directly visualized by integrating the 1299 cm-1, 1600 cm-1 and 3400 cm-1 band, respectively. For detailed insights into compositional changes of these polymers vertex component analysis was performed on selected sample positions. Changes have been elucidated in the composition of lignin within the lignified tissues and between interfascicular fibers and xylem vessels. Hydrophobising changes were revealed from the epidermal layer to the cuticle as well as a change in the aromatic composition within the cuticle of trichomes. To verify Raman signatures of different waterproofing polymers additionally Raman spectra of the cuticle and cutin monomer from tomato (Solanum lycopersicum) as well as aromatic model polymers (milled wood lignin and dehydrogenation polymer of coniferyl alcohol) and phenolic acids were acquired. Keywords: Arabidopsis thaliana, lignin, cutin, wax, Raman, cuticle, waterproofing, secondary cell wall, trichomes

Elaiophore Structure and Oil Secretion in Flowers of Oncidium trulliferum Lindl. and Ornithophora radicans (Rchb.f.) Garay & Pabst (Oncidiinae: Orchidaceae)

PubMed Central

Stpiczyńska, Malgorzata; Davies, Kevin L.

2008-01-01

Background and Aims Many orchid flowers have glands called elaiophores and these reward pollinating insects with oil. In contrast to other reward-producing structures such as nectaries, the anatomy of the elaiophore and the process of oil secretion have not been extensively studied. In this paper, elaiophore structure is described for two members of Oncidiinae, Oncidium trulliferum Lindl. and Ornithophora radicans (Rchb.f.) Garay & Pabst. Methods Elaiophores of both species were examined using light microscopy, scanning electron microscopy and transmission electron microscopy. Key Results and Conclusions In flowers of Oncidium trulliferum and Ornithophora radicans, oil is secreted by morphologically distinct elaiophores associated with the labellar callus. However, in O. trulliferum, elaiophores also occur on the lateral lobes of the labellum. In both these species, the epithelial elaiophores are composed of a single layer of palisade-like epidermal cells and a distinct subepithelial layer. Secretory elaiophore cells may contain numerous, starchless plastids, mitochondria and smooth endoplasmic reticulum profiles. In O. trulliferum, the cytoplasm contains myelin-like figures but these are absent from O. radicans. In the former species, cavities occur in the cell wall and these presumably facilitate the passage of oil onto the elaiophore surface. In O. radicans, the accumulation of oil between the outer tangential wall and the cuticle causes the latter to become distended. Since it is probable that the full discharge of oil from the elaiophores of O. radicans occurs only when the cuticle is ruptured by a visiting insect, this may contribute towards pollinator specificity. The structure of the elaiophore in these species resembles both that found in previously investigated species of Oncidiinae and that of certain members of the Malpighiaceae. PMID:18056056

Langerhans' cell expression of the selectin ligand, sialyl Lewis x.

PubMed Central

Ross, E L; Barker, J N; Allen, M H; Chu, A C; Groves, R W; MacDonald, D M

1994-01-01

Cellular adhesion molecules play a central role in leucocyte migration through peripheral blood and tissues. A crucial stage in these events in selectin-mediated adhesion involving E-selectin expressed on activated endothelium interacting with a range of carbohydrate ligands expressed by specific subpopulations of leucocytes. As such mechanisms may be relevant to bone marrow-derived dendritic epidermal Langerhans' cell (LC) migration, expression of these carbohydrate ligands was assessed immunocytochemically in whole skin biopsies and in epidermal cell suspensions obtained from adult humans. Double-labelling experiments revealed that sialyl Lewis x, recognized by the monoclonal antibody CSLEX1, was expressed on epidermal LC (n = 9). Furthermore, expression was enhanced at 24 hr following epicutaneous application of antigen and in the inflammatory disorder psoriasis (n = 10). E-selectin was concomitantly strongly expressed on dermal endothelium in psoriasis and allergic contact dermatitis. Intradermal injection of the T-cell-derived cytokine interferon-gamma (IFN-gamma) led to increased LC expression of sialyl Lewis x. In epidermal cell suspensions, in contrast to keratinocytes, CD1a+ cells expressed sialyl Lewis x, intensity of which was enhanced after 4 days in culture. CSLEX1 staining could be abolished and CD15 (non-sialated Lewis x) expression induced by saponification and treatment with neuraminidase. Expression of other selectin ligands was also examined. While the cutaneous lymphocyte antigen defined by the monoclonal antibody HECA-452 reacted with a small minority of LC, sialyl Lewis a and sulphatide were not expressed under any experimental conditions. These studies indicate that E-selectin-sialyl Lewis x interactions are potentially important in LC migration, both into and out of skin. Images Figure 2 Figure 3 Figure 5 Figure 6 PMID:7512530

Catalytic Antioxidant Aeol 10150 Treatment Ameliorates Sulfur Mustard Analog 2-Chloroethyl Ethyl Sulfide Associated Cutaneous Toxic Effects

PubMed Central

Tewari-Singh, Neera; Inturi, Swetha; Jain, Anil K.; Agarwal, Chapla; Orlicky, David J; White, Carl W.; Agarwal, Rajesh; Day, Brian J.

2014-01-01

Our previous studies and other published reports with the chemical warfare agent sulfur mustard (SM) and its analog 2-chloroethyl ethyl sulfide (CEES) have indicated a role of oxidative stress in skin injuries caused by these vesicating agents. We examined the effects of the catalytic antioxidant AEOL 10150 in attenuation of CEES-induced toxicity in our established skin injury models (skin epidermal cells and SKH-1 hairless mice) to validate the role of oxidative stress in the pathophysiology of mustard vesicating agents. Treatment of mouse epidermal JB6 and human HaCaT cells with AEOL 10150 (50 μM) 1 h post CEES exposure resulted in significant (p<0.05) reversal of CEES-induced decreases in both cell viability and DNA synthesis. Similarly, AEOL 10150 treatment 1 h after CEES exposure attenuated CEES-induced DNA damage in these cells. Similar AEOL 10150 treatments also caused significant (p<0.05) reversal of CEES-induced decreases in cell viability in normal human epidermal keratinocytes. Cytoplasmic and mitochondrial reactive oxygen species measurements showed that AEOL 10150 treatment drastically ameliorated the CEES-induced oxidative stress in both JB6 and HaCaT cells. Based on AEOL 10150 pharmacokinetic studies in SKH-1 mouse skin, mice were treated with topical formulation plus subcutaneous (injection; 5 mg/kg) AEOL 10150, 1 h after CEES (4 mg/mouse) exposure and every 4 h thereafter for 12 h. This AEOL 10150 treatment regimen resulted in over 50% (p<0.05) reversal in CEES-induced skin bi-fold and epidermal thickness, myeloperoxidase activity, and DNA oxidation in mouse skin. Results from this study demonstrate potential therapeutic efficacy of AEOL 10150 against CEES-mediated cutaneous lesions supporting AEOL 10150 as a medical countermeasure against SM-induced skin injuries. PMID:24815113

Protective effects of amifostine and cyclooxygenase-1 inhibitor against normal human epidermal keratinocyte toxicity induced by methotrexate and 5-fluorouracil.

PubMed

Maiguma, Takayoshi; Kaji, Hiroaki; Makino, Kazutaka; Teshima, Daisuke

2009-07-01

Our study aimed to find more effective protective agents against mucosa toxicity induced by methotrexate and 5-fluorouracil. We focused on the relationship between oral mucositis and keratinocyte injury and examined methotrexate and 5-fluorouracil-induced cytotoxicity in normal human epidermal keratinocyte cell lines. Cell viability and superoxide radical activity were measured based on converting WST-1 (4-[3-(4-indophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzen disulfonate) to a water-soluble formazan dye. DNA synthesis by 5-bromo-2'-deoxyuridine incorporation was measured as an indirect parameter of cell proliferation. Allopurinol and amifostine were used as the radical scavengers. l-glutamine was used as a mucosa-protective agent. A cyclooxygenase inhibitor interrupting the production of hydroxyl radicals in the arachidonic acid cascade was also examined. 5-fluorouracil and methotrexate caused cytotoxicity due to the activation of intracellular superoxide radicals specifically on normal human epidermal keratinocytes. From the electron spin resonance study, it was found that allopurinol was a superoxide radical scavenger, while amifostine was hydroxyl radical scavenger. Allopurinol showed no effect on the cytotoxicity due to 5-fluorouracil and methotrexate. The cell injury induced by methotrexate was restored by amifostine. However, the cell injury induced by 5-fluorouracil was markedly recovered by a selective cyclooxygenase-1 inhibitor compared to amifostine. It was suggested that amifostine and cyclooxygenase-1 inhibitor could be useful protective agents against methotrexate and 5-fluorouracil chemotherapeutic toxicity. Additionally, this in vitro cell injury model using normal human epidermal keratinocytes may be useful for understanding the pathophysiology of oral mucositis induced by chemotherapeutic agents.

The molecular network governing nodule organogenesis and infection in the model legume Lotus japonicus.

PubMed

Madsen, Lene H; Tirichine, Leïla; Jurkiewicz, Anna; Sullivan, John T; Heckmann, Anne B; Bek, Anita S; Ronson, Clive W; James, Euan K; Stougaard, Jens

2010-04-12

Bacterial infection of interior tissues of legume root nodules is controlled at the epidermal cell layer and is closely coordinated with progressing organ development. Using spontaneous nodulating Lotus japonicus plant mutants to uncouple nodule organogenesis from infection, we have determined the role of 16 genes in these two developmental processes. We show that host-encoded mechanisms control three alternative entry processes operating in the epidermis, the root cortex and at the single cell level. Single cell infection did not involve the formation of trans-cellular infection threads and was independent of host Nod-factor receptors and bacterial Nod-factor signals. In contrast, Nod-factor perception was required for epidermal root hair infection threads, whereas primary signal transduction genes preceding the secondary Ca2+ oscillations have an indirect role. We provide support for the origin of rhizobial infection through direct intercellular epidermal invasion and subsequent evolution of crack entry and root hair invasions observed in most extant legumes.

Epidermal Transglutaminase (TGase 3) Is Required for Proper Hair Development, but Not the Formation of the Epidermal Barrier

PubMed Central

John, Susan; Thiebach, Lars; Frie, Christian; Mokkapati, Sharada; Bechtel, Manuela; Nischt, Roswitha; Rosser-Davies, Sally; Paulsson, Mats; Smyth, Neil

2012-01-01

Transglutaminases (TGase), a family of cross-linking enzymes present in most cell types, are important in events as diverse as cell-signaling and matrix stabilization. Transglutaminase 1 is crucial in developing the epidermal barrier, however the skin also contains other family members, in particular TGase 3. This isoform is highly expressed in the cornified layer, where it is believed to stabilize the epidermis and its reduction is implicated in psoriasis. To understand the importance of TGase 3 in vivo we have generated and analyzed mice lacking this protein. Surprisingly, these animals display no obvious defect in skin development, no overt changes in barrier function or ability to heal wounds. In contrast, hair lacking TGase 3 is thinner, has major alterations in the cuticle cells and hair protein cross-linking is markedly decreased. Apparently, while TGase 3 is of unique functional importance in hair, in the epidermis loss of TGase 3 can be compensated for by other family members. PMID:22496784

Generation of Genetically Modified Organotypic Skin Cultures Using Devitalized Human Dermis.

PubMed

Li, Jingting; Sen, George L

2015-12-14

Organotypic cultures allow the reconstitution of a 3D environment critical for cell-cell contact and cell-matrix interactions which mimics the function and physiology of their in vivo tissue counterparts. This is exemplified by organotypic skin cultures which faithfully recapitulates the epidermal differentiation and stratification program. Primary human epidermal keratinocytes are genetically manipulable through retroviruses where genes can be easily overexpressed or knocked down. These genetically modified keratinocytes can then be used to regenerate human epidermis in organotypic skin cultures providing a powerful model to study genetic pathways impacting epidermal growth, differentiation, and disease progression. The protocols presented here describe methods to prepare devitalized human dermis as well as to genetically manipulate primary human keratinocytes in order to generate organotypic skin cultures. Regenerated human skin can be used in downstream applications such as gene expression profiling, immunostaining, and chromatin immunoprecipitations followed by high throughput sequencing. Thus, generation of these genetically modified organotypic skin cultures will allow the determination of genes that are critical for maintaining skin homeostasis.

Computational modeling of epidermal cell fate determination systems.

PubMed

Ryu, Kook Hui; Zheng, Xiaohua; Huang, Ling; Schiefelbein, John

2013-02-01

Cell fate decisions are of primary importance for plant development. Their simple 'either-or' outcome and dynamic nature has attracted the attention of computational modelers. Recent efforts have focused on modeling the determination of several epidermal cell types in the root and shoot of Arabidopsis where many molecular components have been defined. Results of integrated modeling and molecular biology experimentation in these systems have highlighted the importance of competitive positive and negative factors and interconnected feedback loops in generating flexible yet robust mechanisms for establishing distinct gene expression programs in neighboring cells. These models have proven useful in judging hypotheses and guiding future research. Copyright © 2012 Elsevier Ltd. All rights reserved.

Cell signals allow the expression of a pre-existent neural pattern in C. elegans.

PubMed

Waring, D A; Wrischnik, L; Kenyon, C

1992-10-01

In C. elegans, a simple pattern develops within a row of epidermal precursor cells, V1-V6. One cell, V5, gives rise to a neuroblast called the postdeirid neuroblast, while the other V cells produce epidermal cells instead. Here we describe experiments suggesting that in order for V5 to produce the postdeirid it must be in close or direct contact with neighboring V cells. Signaling between V cells is required for the formation of the neuroblast; however, which of the V cells can make a postdeirid is not determined by these signals but rather by the action of the homeotic lin-22 and pal-1 genes. These genes prevent V cells in specific body regions from responding to intercellular signals and producing postdeirids. This is a clear example of cell signals playing a permissive rather than an instructive role in neuroblast induction.

Matrix metalloproteinases and epidermal wound repair.

PubMed

Martins, Vera L; Caley, Matthew; O'Toole, Edel A

2013-02-01

Epidermal wound healing is a complex and highly coordinated process where several different cell types and molecules, such as growth factors and extracellular matrix (ECM) components, play an important role. Among the many proteins that are essential for the restoration of tissue integrity is the metalloproteinase (MMP) family. MMPs can act on ECM and non-ECM components affecting degradation and modulation of the ECM, growth-factor activation and cell-cell and cell-matrix signalling. MMPs are secreted by different cell types such as keratinocytes, fibroblasts and inflammatory cells at different stages and locations during wound healing, thereby regulating this process in a very coordinated and controlled way. In this article, we review the role of MMPs and their inhibitors (TIMPs), as well as the disintegrin and metalloproteinase with the thrombospondin motifs (ADAMs) family, in epithelial wound repair.

Evidence for alternative trapping strategies in two forms of the pitcher plant, Nepenthes rafflesiana

PubMed Central

Bauer, Ulrike; Grafe, T. Ulmar; Federle, Walter

2011-01-01

Nepenthes pitchers are specialized leaves that function as insect traps. Several pitcher components may contribute to trapping, including the pitcher fluid, slippery wax crystals and downward-pointing epidermal cells on the inner pitcher wall, and the wetness-dependent pitcher rim (peristome), but the relative importance of these traits is unclear. Mechanisms of prey capture and retention in the field were investigated by quantifying the effect of ‘knock-out’ manipulations of individual pitcher structures, and by testing the ability of pitcher fluids and water to retain insects. Two forms of Nepenthes rafflesiana Jack (‘elongate’ and ‘typical’) with contrasting combinations of pitcher traits were compared. Wax crystals on the inner pitcher wall were found to be the most important trapping structure in the elongate form, whereas the typical form relied primarily on the peristome. The pitcher fluids of both forms, differing markedly in the degree of viscoelasticity, retained significantly more ants than water. The present results show that pitcher plants utilize several mechanisms for prey capture and retention, varying in efficiency and relative importance between forms. It is proposed that these differences represent alternative prey capture strategies that may provide a mechanism to reduce competition and facilitate species co-existence in nutrient-limited habitats. PMID:21459766

Evidence for alternative trapping strategies in two forms of the pitcher plant, Nepenthes rafflesiana.

PubMed

Bauer, Ulrike; Grafe, T Ulmar; Federle, Walter

2011-06-01

Nepenthes pitchers are specialized leaves that function as insect traps. Several pitcher components may contribute to trapping, including the pitcher fluid, slippery wax crystals and downward-pointing epidermal cells on the inner pitcher wall, and the wetness-dependent pitcher rim (peristome), but the relative importance of these traits is unclear. Mechanisms of prey capture and retention in the field were investigated by quantifying the effect of 'knock-out' manipulations of individual pitcher structures, and by testing the ability of pitcher fluids and water to retain insects. Two forms of Nepenthes rafflesiana Jack ('elongate' and 'typical') with contrasting combinations of pitcher traits were compared. Wax crystals on the inner pitcher wall were found to be the most important trapping structure in the elongate form, whereas the typical form relied primarily on the peristome. The pitcher fluids of both forms, differing markedly in the degree of viscoelasticity, retained significantly more ants than water. The present results show that pitcher plants utilize several mechanisms for prey capture and retention, varying in efficiency and relative importance between forms. It is proposed that these differences represent alternative prey capture strategies that may provide a mechanism to reduce competition and facilitate species co-existence in nutrient-limited habitats.

Abnormalities in the basement membrane structure promote basal keratinocytes in the epidermis of hypertrophic scars to adopt a proliferative phenotype.

PubMed

Yang, Shaowei; Sun, Yexiao; Geng, Zhijun; Ma, Kui; Sun, Xiaoyan; Fu, Xiaobing

2016-05-01

The majority of studies on scar formation have mainly focused on the dermis and little is known of the involvement of the epidermis. Previous research has demonstrated that the scar tissue-derived keratinocytes are different from normal cells at both the genetic and cell biological levels; however, the mechanisms responsible for the fundamental abnormalities in keratinocytes during scar development remain elusive. For this purpose, in this study, we used normal, wound edge and hypertrophic scar tissue to examine the morphological changes which occur during epidermal regeneration as part of the wound healing process and found that the histological structure of hypertrophic scar tissues differed from that of normal skin, with a significant increase in epidermal thickness. Notably, staining of the basement membrane (BM) appeared to be absent in the scar tissues. Moreover, immunofluorescence staining for cytokeratin (CK)10, CK14, CK5, CK19 and integrin-β1 indicated the differential expression of cell markers in the epidermal keratinocytes among the normal, wound edge and hypertrophic scar tissues, which corresponded with the altered BM structures. By using a panel of proteins associated with BM components, we validated our hypothesis that the BM plays a significant role in regulating the cell fate decision of epidermal keratinocytes during skin wound healing. Alterations in the structure of the BM promote basal keratinocytes to adopt a proliferative phenotype both in vivo and in vitro.

Abnormalities in the basement membrane structure promote basal keratinocytes in the epidermis of hypertrophic scars to adopt a proliferative phenotype

PubMed Central

YANG, SHAOWEI; SUN, YEXIAO; GENG, ZHIJUN; MA, KUI; SUN, XIAOYAN; FU, XIAOBING

2016-01-01

The majority of studies on scar formation have mainly focused on the dermis and little is known of the involvement of the epidermis. Previous research has demonstrated that the scar tissue-derived keratinocytes are different from normal cells at both the genetic and cell biological levels; however, the mechanisms responsible for the fundamental abnormalities in keratinocytes during scar development remain elusive. For this purpose, in this study, we used normal, wound edge and hypertrophic scar tissue to examine the morphological changes which occur during epidermal regeneration as part of the wound healing process and found that the histological structure of hypertrophic scar tissues differed from that of normal skin, with a significant increase in epidermal thickness. Notably, staining of the basement membrane (BM) appeared to be absent in the scar tissues. Moreover, immunofluorescence staining for cytokeratin (CK)10, CK14, CK5, CK19 and integrin-β1 indicated the differential expression of cell markers in the epidermal keratinocytes among the normal, wound edge and hypertrophic scar tissues, which corresponded with the altered BM structures. By using a panel of proteins associated with BM components, we validated our hypothesis that the BM plays a significant role in regulating the cell fate decision of epidermal keratinocytes during skin wound healing. Alterations in the structure of the BM promote basal keratinocytes to adopt a proliferative phenotype both in vivo and in vitro. PMID:26986690

A randomized trial comparing ReCell system of epidermal cells delivery versus classic skin grafts for the treatment of deep partial thickness burns.

PubMed

Gravante, G; Di Fede, M C; Araco, A; Grimaldi, M; De Angelis, B; Arpino, A; Cervelli, V; Montone, A

2007-12-01

Our purpose was to directly compare results obtained with the ReCell system and the classic skin grafting for epidermal replacement in deep partial thickness burns. We recruited all patients with deep partial thickness burns admitted at the Burn Centre of S. Eugenio Hospital in Rome over 2 years. Enrollment was conducted with a controlled strategy--sampling chart--that allowed homogeneous groups (ReCell and skin grafting) for age, gender, type of burns and total burn surface area (TBSA). We evaluated as primary endpoints of the study the (i) time for complete epithelization (both treated area and biopsy site) and (ii) aesthetic and functional quality of the epithelization (color, joint contractures). Secondary endpoints were the assessment of infections, inflammations or any adverse effects of the ReCell procedure, particular medications assumed, postoperative pain. Eighty-two patients were analyzed in two homogeneous groups. All of them received adequate epidermal replacement, but skin grafting was faster than ReCell (p<0.05). On the contrary, ReCell biopsy areas and postoperative pain were smaller than classic grafting (p<0.05). The aesthetic and functional outcomes were similar between procedures. ReCell is a feasible, simple and safe technique. It gives similar results to skin grafting but, harvesting minor areas, can open possible future applications in the management of large-burns patients.

Stomatal Spacing Safeguards Stomatal Dynamics by Facilitating Guard Cell Ion Transport Independent of the Epidermal Solute Reservoir12[CC-BY

PubMed Central

Papanatsiou, Maria; Amtmann, Anna

2016-01-01

Stomata enable gaseous exchange between the interior of the leaf and the atmosphere through the stomatal pore. Control of the pore aperture depends on osmotic solute accumulation by, and its loss from the guard cells surrounding the pore. Stomata in most plants are separated by at least one epidermal cell, and this spacing is thought to enhance stomatal function, although there are several genera that exhibit stomata in clusters. We made use of Arabidopsis (Arabidopsis thaliana) stomatal patterning mutants to explore the impact of clustering on guard cell dynamics, gas exchange, and ion transport of guard cells. These studies showed that stomatal clustering in the Arabidopsis too many mouths (tmm1) mutant suppressed stomatal movements and affected CO2 assimilation and transpiration differentially between dark and light conditions and were associated with alterations in K+ channel gating. These changes were consistent with the impaired dynamics of tmm1 stomata and were accompanied by a reduced accumulation of K+ ions in the guard cells. Our findings underline the significance of spacing for stomatal dynamics. While stomatal spacing may be important as a reservoir for K+ and other ions to facilitate stomatal movements, the effects on channel gating, and by inference on K+ accumulation, cannot be explained on the basis of a reduced number of epidermal cells facilitating ion supply to the guard cells. PMID:27406168

Inhibition of epidermal growth factor receptor by ferulic acid and 4-vinylguaiacol in human breast cancer cells.

PubMed

Sudhagar, S; Sathya, S; Anuradha, R; Gokulapriya, G; Geetharani, Y; Lakshmi, B S

2018-02-01

To examine the potential of ferulic acid and 4-vinylguaiacol for inhibiting epidermal growth factor receptor (EGFR) in human breast cancer cells in vitro. Ferulic acid and 4-vinylguaiacol limit the EGF (epidermal growth factor)-induced breast cancer proliferation and new DNA synthesis. Western blot analysis revealed both ferulic acid and 4-vinylguaiacol exhibit sustained inhibition of EGFR activation through down-regulation of Tyr 1068 autophosphorylation. Molecular docking analysis shows ferulic acid forming hydrogen bond interaction with Lys 745 and Met 793 whereas, 4-vinylguaiacol forms two hydrogen bonds with Phe 856 and exhibits stronger hydrophobic interactions with multiple amino acid residues at the EGFR kinase domain. Ferulic acid and 4-vinylguaiacol could serve as a potential structure for the development of new small molecule therapeutics against EGFR.

Whole organ, venation and epidermal cell morphological variations are correlated in the leaves of Arabidopsis mutants.

PubMed

Pérez-Pérez, José Manuel; Rubio-Díaz, Silvia; Dhondt, Stijn; Hernández-Romero, Diana; Sánchez-Soriano, Joaquín; Beemster, Gerrit T S; Ponce, María Rosa; Micol, José Luis

2011-12-01

Despite the large number of genes known to affect leaf shape or size, we still have a relatively poor understanding of how leaf morphology is established. For example, little is known about how cell division and cell expansion are controlled and coordinated within a growing leaf to eventually develop into a laminar organ of a definite size. To obtain a global perspective of the cellular basis of variations in leaf morphology at the organ, tissue and cell levels, we studied a collection of 111 non-allelic mutants with abnormally shaped and/or sized leaves, which broadly represent the mutational variations in Arabidopsis thaliana leaf morphology not associated with lethality. We used image-processing techniques on these mutants to quantify morphological parameters running the gamut from the palisade mesophyll and epidermal cells to the venation, whole leaf and rosette levels. We found positive correlations between epidermal cell size and leaf area, which is consistent with long-standing Avery's hypothesis that the epidermis drives leaf growth. In addition, venation parameters were positively correlated with leaf area, suggesting that leaf growth and vein patterning share some genetic controls. Positional cloning of the genes affected by the studied mutations will eventually establish functional links between genotypes, molecular functions, cellular parameters and leaf phenotypes. © 2011 Blackwell Publishing Ltd.

Galvanic zinc-copper microparticles inhibit melanogenesis via multiple pigmentary pathways.

PubMed

Won, Yen-Kim; Lin, Connie B; Seiberg, Miri; Chen, Nannan; Hu, Yaping; Rossetti, Dianne; Saliou, Claude; Loy, Chong-Jin

2014-01-01

The endogenous electrical field of human skin plays an important role in many skin functions. However, the biological effects and mechanism of action of externally applied electrical stimulation on skin remain unclear. Recent study showed that galvanic zinc-copper microparticles produce electrical stimulation and reduce inflammatory and immune responses in intact skin, suggesting the important role of electrical stimulation in non-wounded skin. The objective of this study is to investigate the biological effect of galvanic zinc-copper microparticles on skin pigmentation. Our findings showed that galvanic zinc-copper microparticles inhibited melanogenesis in a human melanoma cell line (MNT-1), human keratinocytes and melanoma cells co-cultures, and in pigmented epidermal equivalents. Treatment of galvanic zinc-copper microparticles inhibited melanogenesis by reducing the promoter transactivation of tyrosinase and tyrosinase-related protein-1 in human melanoma cells. In a co-culture Transwell system of keratinocytes and melanoma cells, galvanic zinc-copper microparticles reduced melanin production via downregulation of endothelin-1 secretion from keratinocytes and reduced tyrosinase gene expression in melanoma cells. In addition, exposure of pigmented epidermal equivalents to galvanic zinc-copper microparticles resulted in reduced melanin deposition. In conclusion, our data demonstrated for the first time that galvanic zinc-copper microparticles reduced melanogenesis in melanoma cells and melanin deposition in pigmented epidermal equivalents by affecting multiple pigmentary pathways.

Squamous cell cancer (image)

MedlinePlus

Squamous cell cancer involves cancerous changes to the cells of the middle portion of the epidermal skin layer. It is ... malignant tumor, and is more aggressive than basal cell cancer, but still may be relatively slow-growing. It ...

Establishment and characterization of a new human functional cell line from a choriocarcinoma.

PubMed

Okabe, T; Sasaki, N; Matsuzaki, M; Imai, Y; Kaneko, Y; Matsuzaki, F; Takaku, F; Tsushima, T

1983-10-01

A new human functional tumor cell line, designated as T3M-3, has been established from a xenotransplanted choriocarcinoma grown in nude mice. One of the biggest problems of the in vitro culture of these tumor cells using the xenotransplanted tumors had been the dense contamination of fibroblasts of host nude mouse origin. In the present study, these fibroblasts were completely removed by incubating the cells with antiserum raised against nude mouse spleen cells. The cell line established from the remaining tumor cells has been successfully propagated in vitro for as long as 4 years. These cells show the morphology of epithelioid cells containing a prominent nucleus with one or two large nucleoli. The cells grow in a monolayered sheet with the population-doubling time of 19 hr. The cells show perfect tumor takes when they are reinoculated into nude mice. Chromosomal analysis revealed that the cell is a human aneuploid one with a hypotriploid mode. These cultured cells maintained well the function of secreting large amounts of human chorionic gonadotropin, progesterone, and estrogen. The secretion of human chorionic gonadotropin and progesterone by these cells is enhanced by stimulation with tumor promoters, such as 12-O-tetradecanoylphorbol-13-acetate and teleocidin B, or with epidermal growth factor in a dose-and time-dependent manner. Interestingly, however, the tumor promoters did not exert a marked effect on the cellular binding of epidermal growth factor, indicating that the receptors for these reagents in T3M-3 cells are not shared by epidermal growth factor.

Ectopic Atoh1 expression drives Merkel cell production in embryonic, postnatal and adult mouse epidermis.

PubMed

Ostrowski, Stephen M; Wright, Margaret C; Bolock, Alexa M; Geng, Xuehui; Maricich, Stephen M

2015-07-15

Merkel cells are mechanosensitive skin cells whose production requires the basic helix-loop-helix transcription factor Atoh1. We induced ectopic Atoh1 expression in the skin of transgenic mice to determine whether Atoh1 was sufficient to create additional Merkel cells. In embryos, ectopic Atoh1 expression drove ectopic expression of the Merkel cell marker keratin 8 (K8) throughout the epidermis. Epidermal Atoh1 induction in adolescent mice similarly drove widespread K8 expression in glabrous skin of the paws, but in the whisker pads and body skin ectopic K8+ cells were confined to hair follicles and absent from interfollicular regions. Ectopic K8+ cells acquired several characteristics of mature Merkel cells in a time frame similar to that seen during postnatal development of normal Merkel cells. Although ectopic K8+ cell numbers decreased over time, small numbers of these cells remained in deep regions of body skin hair follicles at 3 months post-induction. In adult mice, greater numbers of ectopic K8+ cells were created by Atoh1 induction during anagen versus telogen and following disruption of Notch signaling by conditional deletion of Rbpj in the epidermis. Our data demonstrate that Atoh1 expression is sufficient to produce new Merkel cells in the epidermis, that epidermal cell competency to respond to Atoh1 varies by skin location, developmental age and hair cycle stage, and that the Notch pathway plays a key role in limiting epidermal cell competency to respond to Atoh1 expression. © 2015. Published by The Company of Biologists Ltd.

Floral nectar production and carbohydrate composition and the structure of receptacular nectaries in the invasive plant Bunias orientalis L. (Brassicaceae).

PubMed

Denisow, Bożena; Masierowska, Marzena; Antoń, Sebastian

2016-11-01

The data relating to the nectaries and nectar secretion in invasive Brassicacean taxa are scarce. In the present paper, the nectar production and nectar carbohydrate composition as well as the morphology, anatomy and ultrastructure of the floral nectaries in Bunias orientalis were investigated. Nectary glands were examined using light, fluorescence, scanning electron and transmission electron microscopy. The quantities of nectar produced by flowers and total sugar mass in nectar were relatively low. Total nectar carbohydrate production per 10 flowers averaged 0.3 mg. Nectar contained exclusively glucose (G) and fructose (F) with overall G/F ratio greater than 1. The flowers of B. orientalis have four nectaries placed at the base of the ovary. The nectarium is intermediate between two nectary types: the lateral and median nectary type (lateral and median glands stay separated) and the annular nectary type (both nectaries are united into one). Both pairs of glands represent photosynthetic type and consist of epidermis and glandular tissue. However, they differ in their shape, size, secretory activity, dimensions of epidermal and parenchyma cells, thickness of secretory parenchyma, phloem supply, presence of modified stomata and cuticle ornamentation. The cells of nectaries contain dense cytoplasm, plastids with starch grains and numerous mitochondria. Companion cells of phloem lack cell wall ingrowths. The ultrastructure of secretory cells indicates an eccrine mechanism of secretion. Nectar is exuded throughout modified stomata.

Disruption of Sorting Nexin 5 Causes Respiratory Failure Associated with Undifferentiated Alveolar Epithelial Type I Cells in Mice

PubMed Central

Im, Sun-Kyoung; Jeong, HyoBin; Jeong, Hyun-Woo; Kim, Kyong-Tai; Hwang, Daehee; Ikegami, Machiko; Kong, Young-Yun

2013-01-01

Sorting nexin 5 (Snx5) has been posited to regulate the degradation of epidermal growth factor receptor and the retrograde trafficking of cation-independent mannose 6-phosphate receptor/insulin-like growth factor II receptor. Snx5 has also been suggested to interact with Mind bomb-1, an E3 ubiquitin ligase that regulates the activation of Notch signaling. However, the in vivo functions of Snx5 are largely unknown. Here, we report that disruption of the Snx5 gene in mice (Snx5-/- mice) resulted in partial perinatal lethality; 40% of Snx5-/- mice died shortly after birth due to cyanosis, reduced air space in the lungs, and respiratory failure. Histological analysis revealed that Snx5-/- mice exhibited thickened alveolar walls associated with undifferentiated alveolar epithelial type I cells. In contrast, alveolar epithelial type II cells were intact, exhibiting normal surfactant synthesis and secretion. Although the expression levels of surfactant proteins and saturated phosphatidylcholine in the lungs of Snx5-/- mice were comparable to those of Snx5+/+ mice, the expression levels of T1α, Aqp5, and Rage, markers for distal alveolar epithelial type I cells, were significantly decreased in Snx5 -/- mice. These results demonstrate that Snx5 is necessary for the differentiation of alveolar epithelial type I cells, which may underlie the adaptation to air breathing at birth. PMID:23526992

Oncogenic Ras: A double-edged sword for human epidermal stem and transient amplifying cells

PubMed Central

Dellambra, Elena

2016-01-01

ABSTRACT The human epidermal clonal evolution, i.e. the transition from stem cells (SCs) to transient amplifying (TA)-cells and post-mitotic cells, is a continuous and tightly regulated process that ensures physiologic tissue homeostasis. The Ras family of small GTPases has a key role in skin homeostasis and tumorigenesis. Indeed, activating mutations in Ras genes have been found in human cutaneous squamous cell carcinomas (cSCCs) and in experimentally-induced murine cSCCs. In mouse models, the Ras signaling might lead to hyperproliferative phenotypes, including the development of cSCCs, depending on the nature of the founding cells. Tumor-initiating cells or Cancer Stem Cells (CSCs) have been demonstrated in murine and human cSCCs even if the mechanism of their development from normal SCs or TA-cells is not completely elucidated. Here, the relation between the Ras expression outcome and the clonogenic potential of the target keratinocyte is discussed. PMID:27111451

Human Epidermal Langerhans Cells Maintain Immune Homeostasis in Skin by Activating Skin Resident Regulatory T Cells

PubMed Central

Seneschal, Julien; Clark, Rachael A.; Gehad, Ahmed; Baecher-Allan, Clare M.; Kupper, Thomas S.

2013-01-01

Recent discoveries indicate that the skin of a normal individual contains 10-20 billion resident memory T cells ( which include various T helper, T cytotoxic, and T regulatory subsets, that are poised to respond to environmental antigens. Using only autologous human tissues, we report that both in vitro and in vivo, resting epidermal Langerhan cells (LC) selectively and specifically induced the activation and proliferation of skin resident regulatory T cells (Treg), a minor subset of skin resident memory T cells. In the presence of foreign pathogen, however, the same LC activated and induced proliferation of effector memory T (Tem) cells and limited Treg cells activation. These underappreciated properties of LC: namely maintenance of tolerance in normal skin, and activation of protective skin resident memory T cells upon infectious challenge, help clarify the role of LC in skin. PMID:22560445

Burn Injury Alters Epidermal Cholinergic Mediators and Increases HMGB1 and Caspase 3 in Autologous Donor Skin and Burn Margin

PubMed Central

Holmes, Casey J.; Plichta, Jennifer K.; Gamelli, Richard L.; Radek, Katherine A.

2016-01-01

Burn wound healing complications, such as graft failure or infection, are a major source of morbidity and mortality in burn patients. The mechanisms by which local burn injury alters epidermal barrier function in autologous donor skin and surrounding burn margin are largely undefined. We hypothesized that defects in the epidermal cholinergic system may impair epidermal barrier function and innate immune responses. The objective was to identify alterations in the epidermal cholinergic pathway, and their downstream targets, associated with inflammation and cell death. We established that protein levels, but not gene expression, of the α7 nicotinic acetylcholine receptor (CHRNA7) were significantly reduced in both donor and burn margin skin. Furthermore, the gene and protein levels of an endogenous allosteric modulator of CHRNA7, secreted mammalian Ly-6/urokinase-type plasminogen activator receptor-related protein-1 (SLURP1) and acetylcholine were significantly elevated in donor and burn margin skin. As downstream proteins of inflammatory and cell death targets of nAChR activation, we found significant elevations in epidermal High Mobility Group Box Protein 1 (HMGB1) and caspase 3 in donor and burn margin skin. Lastly, we employed a novel in vitro keratinocyte burn model to establish that burn injury influences the gene expression of these cholinergic mediators and their downstream targets. These results indicate that defects in cholinergic mediators and inflammatory/apoptotic molecules in donor and burn margin skin may directly contribute to graft failure or infection in burn patients. PMID:27648692

Ablation of Coactivator Med1 Switches the Cell Fate of Dental Epithelia to That Generating Hair

PubMed Central

Nguyen, Thai; Sakai, Kiyoshi; He, Bing; Fong, Chak; Oda, Yuko

2014-01-01

Cell fates are determined by specific transcriptional programs. Here we provide evidence that the transcriptional coactivator, Mediator 1 (Med1), is essential for the cell fate determination of ectodermal epithelia. Conditional deletion of Med1 in vivo converted dental epithelia into epidermal epithelia, causing defects in enamel organ development while promoting hair formation in the incisors. We identified multiple processes by which hairs are generated in Med1 deficient incisors: 1) dental epithelial stem cells lacking Med 1 fail to commit to the dental lineage, 2) Sox2-expressing stem cells extend into the differentiation zone and remain multi-potent due to reduced Notch1 signaling, and 3) epidermal fate is induced by calcium as demonstrated in dental epithelial cell cultures. These results demonstrate that Med1 is a master regulator in adult stem cells to govern epithelial cell fate. PMID:24949995

Identification of Cell Wall Synthesis Regulatory Genes Controlling Biomass Characteristics and Yield in Rice (Oryza Sativa)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peng, Zhaohua PEng; Ronald, Palmela; Wang, Guo-Liang

This project aims to identify the regulatory genes of rice cell wall synthesis pathways using a cell wall removal and regeneration system. We completed the gene expression profiling studies following the time course from cell wall removal to cell wall regeneration in rice suspension cells. We also completed, total proteome, nuclear subproteome and histone modification studies following the course from cell wall removal and cell wall regeneration process. A large number of differentially expressed regulatory genes and proteins were identified. Meanwhile, we generated RNAi and over-expression transgenic rice for 45 genes with at least 10 independent transgenic lines for eachmore » gene. In addition, we ordered T-DNA and transposon insertion mutants for 60 genes from Korea, Japan, and France and characterized the mutants. Overall, we have mutants and transgenic lines for over 90 genes, exceeded our proposed goal of generating mutants for 50 genes. Interesting Discoveries a) Cell wall re-synthesis in protoplasts may involve a novel cell wall synthesis mechanism. The synthesis of the primary cell wall is initiated in late cytokinesis with further modification during cell expansion. Phragmoplast plays an essential role in cell wall synthesis. It services as a scaffold for building the cell plate and formation of a new cell wall. Only one phragmoplast and one new cell wall is produced for each dividing cell. When the cell wall was removed enzymatically, we found that cell wall re-synthesis started from multiple locations simultaneously, suggesting that a novel mechanism is involved in cell wall re-synthesis. This observation raised many interesting questions, such as how the starting sites of cell wall synthesis are determined, whether phragmoplast and cell plate like structures are involved in cell wall re-synthesis, and more importantly whether the same set of enzymes and apparatus are used in cell wall re-synthesis as during cytokinesis. Given that many known cell wall synthesis pathway genes are induced by removal of cell wall, some cell wall synthesis apparatus must be shared in both cases. The cell wall re-synthesis mechanism may have broad application because our preliminary assay indicates that the cell wall characteristics are highly different from those produced during cytokinesis. A thorough understanding on the regulation of cell wall re-synthesis may lead to improvement of cell wall characteristics. b) Removal of cell wall results in chromatin decondensation Another interesting observation was that removal of cell wall was associated with substantial chromatin change. Our DNA DAPI stain, chromatin MNase digestion, histone modification proteomics, protein differential expression analysis, and DNA oligo array studies all supported that substantial chromatin change was associated with removal of cell wall treatment. It is still under investigation if the chromatin change is associated with activation of cell wall synthesis genes, in which chromatin remodeling is required. Another possibility is that the cell wall is required for stabilizing the chromatin structure in plant cells. Given that spindle fiber is directly connected with both chromatin structure and cell wall synthesis, it is possible that there is an intrinsic connection between cell wall and chromatin.« less

Epidermal Growth Factor-Dependent Transformation by a Human EGF Receptor Proto-Oncogene

NASA Astrophysics Data System (ADS)

Velu, Thierry J.; Beguinot, Laura; Vass, William C.; Willingham, Mark C.; Merlino, Glenn T.; Pastan, Ira; Lowy, Douglas R.

1987-12-01

The epidermal growth factor (EGF) receptor gene EGFR has been placed in a retrovirus vector to examine the growth properties of cells that experimentally overproduce a full-length EGF receptor. NIH 3T3 cells transfected with the viral DNA or infected with the corresponding rescued retrovirus developed a fully transformed phenotype in vitro that required both functional EGFR expression and the presence of EGF in the growth medium. Cells expressing 4 × 105 EGF receptors formed tumors in nude mice, while control cells did not. Therefore, the EGFR retrovirus, which had a titer on NIH 3T3 cells that was greater than 107 focus-forming units per milliliter, can efficiently transfer and express this gene, and increased numbers of EGF receptors can contribute to the transformed phenotype.

Effect of low-level laser irradiation and epidermal growth factor on adult human adipose-derived stem cells.

PubMed

Mvula, B; Moore, T J; Abrahamse, H

2010-01-01

The study investigated the effects of low-level laser radiation and epidermal growth factor (EGF) on adult adipose-derived stem cells (ADSCs) isolated from human adipose tissue. Isolated cells were cultured to semi-confluence, and the monolayers of ADSCs were exposed to low-level laser at 5 J/cm(2) using 636 nm diode laser. Cell viability and proliferation were monitored using adenosine triphosphate (ATP) luminescence and optical density at 0 h, 24 h and 48 h after irradiation. Application of low-level laser irradiation at 5 J/cm(2) on human ADSCs cultured with EGF increased the viability and proliferation of these cells. The results indicate that low-level laser irradiation in combination with EGF enhances the proliferation and maintenance of ADSCs in vitro.

Emodin Suppresses Maintenance of Stemness by Augmenting Proteosomal Degradation of Epidermal Growth Factor Receptor/Epidermal Growth Factor Receptor Variant III in Glioma Stem Cells

PubMed Central

Kim, Jeongyub; Lee, Jong-Seon; Jung, Jieun; Lim, Inhye; Lee, Ji-Yun

2015-01-01

There is a growing body of evidence that small subpopulations of cells with stem cell-like characteristics within most solid tumors are responsible for the malignancy of aggressive cancer cells and that targeting these cells might be a good therapeutic strategy to reduce the risk of tumor relapse after therapy. Here, we examined the effects of emodin (1,3,8-trihydroxy-6-methylanthraquinone), an active component of the root and rhizome of Rheum palmatum that has several biological activities, including antitumor effects, on primary cultured glioma stem cells (GSCs). Emodin inhibited the self-renewal activity of GSCs in vitro as evidenced by neurosphere formation, limiting dilution, and soft agar clonogenic assays. Emodin inhibited the maintenance of stemness by suppressing the expression of Notch intracellular domain, nonphosphorylated β-catenin, and phosphorylated STAT3 proteins. In addition, treatment with emodin partially induced apoptosis, reduced cell invasiveness, and sensitized GSCs to ionizing radiation. Intriguingly, emodin induced proteosomal degradation of epidermal growth factor receptor (EGFR)/EGFR variant III (EGFRvIII) by interfering with the association of EGFR/EGFRvIII with heat shock protein 90, resulting in the suppression of stemness pathways. Based on these data, we propose that emodin could be considered as a potent therapeutic adjuvant that targets GSCs. PMID:25229646

NASA-approved rotary bioreactor enhances proliferation of human epidermal stem cells and supports formation of 3D epidermis-like structure.

PubMed

Lei, Xiao-hua; Ning, Li-na; Cao, Yu-jing; Liu, Shuang; Zhang, Shou-bing; Qiu, Zhi-fang; Hu, Hui-min; Zhang, Hui-shan; Liu, Shu; Duan, En-kui

2011-01-01

The skin is susceptible to different injuries and diseases. One major obstacle in skin tissue engineering is how to develop functional three-dimensional (3D) substitute for damaged skin. Previous studies have proved a 3D dynamic simulated microgravity (SMG) culture system as a "stimulatory" environment for the proliferation and differentiation of stem cells. Here, we employed the NASA-approved rotary bioreactor to investigate the proliferation and differentiation of human epidermal stem cells (hEpSCs). hEpSCs were isolated from children foreskins and enriched by collecting epidermal stem cell colonies. Cytodex-3 micro-carriers and hEpSCs were co-cultured in the rotary bioreactor and 6-well dish for 15 days. The result showed that hEpSCs cultured in rotary bioreactor exhibited enhanced proliferation and viability surpassing those cultured in static conditions. Additionally, immunostaining analysis confirmed higher percentage of ki67 positive cells in rotary bioreactor compared with the static culture. In contrast, comparing with static culture, cells in the rotary bioreactor displayed a low expression of involucrin at day 10. Histological analysis revealed that cells cultured in rotary bioreactor aggregated on the micro-carriers and formed multilayer 3D epidermis structures. In conclusion, our research suggests that NASA-approved rotary bioreactor can support the proliferation of hEpSCs and provide a strategy to form multilayer epidermis structure.

P16INK4a Positive Cells in Human Skin Are Indicative of Local Elastic Fiber Morphology, Facial Wrinkling, and Perceived Age

PubMed Central

Waaijer, Mariëtte E. C.; Gunn, David A.; Adams, Peter D.; Pawlikowski, Jeff S.; Griffiths, Christopher E. M.; van Heemst, Diana; Slagboom, P. Eline; Westendorp, Rudi G. J.; Maier, Andrea B.

2016-01-01

Senescent cells are more prevalent in aged human skin compared to young, but evidence that senescent cells are linked to other biomarkers of aging is scarce. We counted cells positive for the tumor suppressor and senescence associated protein p16INK4a in sun-protected upper-inner arm skin biopsies from 178 participants (aged 45–81 years) of the Leiden Longevity Study. Local elastic fiber morphology, facial wrinkles, and perceived facial age were compared to tertiles of p16INK4a counts, while adjusting for chronological age and other potential confounders. The numbers of epidermal and dermal p16INK4a positive cells were significantly associated with age-associated elastic fiber morphologic characteristics, such as longer and a greater number of elastic fibers. The p16INK4a positive epidermal cells (identified as primarily melanocytes) were also significantly associated with more facial wrinkles and a higher perceived age. Participants in the lowest tertile of epidermal p16INK4a counts looked 3 years younger than those in the highest tertile, independently of chronological age and elastic fiber morphology. In conclusion, p16INK4a positive cell numbers in sun-protected human arm skin are indicative of both local elastic fiber morphology and the extent of aging visible in the face. PMID:26286607

Thalidomide inhibits tumor necrosis factor-alpha production and antigen presentation by Langerhans cells.

PubMed

Deng, Liang; Ding, Wanhong; Granstein, Richard D

2003-11-01

Thalidomide is an effective treatment for several inflammatory and autoimmune disorders including erythema nodosum leprosum, Behcet's syndrome, discoid lupus erythematosus, and Crohn's disease. Thalidomide is believed to exert its anti-inflammatory effects, at least in part, by inhibiting tumor necrosis factor-alpha (TNF-alpha) production by monocytes. We studied the effects of thalidomide on epidermal Langerhans cells (LC). LCs are epidermal antigen-presenting dendritic cells that play important roles in skin immune responses. Using the murine epidermis-derived dendritic cell lines, XS106A from A/J mice and XS52 from BALB/c mice as surrogates for LC, we found that thalidomide inhibited TNF-alpha production in a concentration-dependent manner. Northern blot analysis revealed that thalidomide significantly decreased the peak-induced mRNA level of TNF-alpha in XS106A cells and XS52 cells. We then examined the effect of thalidomide on fresh LC enriched to approximately 98% using positive selection of Ia+ cells with antibodies conjugated to magnetic microspheres. TNF-alpha production was reduced by 67.7% at a thalidomide concentration of 200 microg per mL. Thalidomide also had a profound inhibitory effect on the ability of LC to present antigen to a responsive TH1 clone. Thalidomide inhibits TNF-alpha production and the antigen-presenting ability of epidermal LCs. These mechanisms may contribute to the therapeutic effects observed with this agent.

3,4-dihydroxyphenyl acetic acid and (+)-epoxydon isolated from marine algae-derived microorganisms induce down regulation of epidermal growth factor activated mitogenic signaling cascade in Hela cells.

PubMed

Jo, Mi Jeong; Bae, Seong Ja; Son, Byeng Wha; Kim, Chi Yeon; Kim, Gun Do

2013-05-25

Epidermal growth factor receptor (EGFR) is a member of the receptor tyrosine kinase (RTK) family. Epidermal growth factor induces its dimerization and stimulates phosphorylation of intracellular tyrosine residues. Phosphorylation of EGFR is studied for cancer therapy because EGFR regulates many cellular processes including cell proliferation, differentiation, and survival. Hence, down-regulation of EGFR kinase activity results in inhibition of signaling cascades amenable for proliferation and progression of cell cycle. In the study, we purified 3,4-dihydroxyphenyl acetic acid and (+)-epoxydon from Aspergillus sp. isolated from marine brown alga Ishige okamurae and Phoma herbarum isolated from marine red alga Hypnea saidana respectively and determined its anti-tumor activities against HeLa human cervical cancer cells. Two compounds suppressed EGFR activity in vitro with IC50 values for 3,4-dihydroxyphenyl acetic acid and (+)-epoxydon were 2.8 and 0.6 μg/mL respectively and reduced the viable numbers of HeLa cells. Immunoblotting analysis exhibited that the compounds induced inhibition of cell growth by causing downregulation of the mitogenic signaling cascade, inactivation of p90RSK, and release of cytochrome c from mitochondria. Results suggest that decreased expression of active EGFR and EGFR-related downstream molecules by treatment with the compounds may results in the inhibition of cell growth and inducement of apoptosis.

Human Adipose Mesenchymal Cells Inhibit Melanocyte Differentiation and the Pigmentation of Human Skin via Increased Expression of TGF-β1.

PubMed

Klar, Agnes S; Biedermann, Thomas; Michalak, Katarzyna; Michalczyk, Teresa; Meuli-Simmen, Claudia; Scherberich, Arnaud; Meuli, Martin; Reichmann, Ernst

2017-12-01

There is accumulating evidence that interactions between epidermal melanocytes and stromal cells play an important role in the regulation of skin pigmentation. In this study we established a pigmented dermo-epidermal skin model, melDESS, of human origin to investigate the effects of distinct stromal cells on melanogenesis. melDESS is a complex, clinically relevant skin equivalent composed of an epidermis containing both melanocytes and keratinocytes. Its dermal compartment consists either of adipose tissue-derived stromal cells, dermal fibroblasts (Fbs), or a mixture of both cell types. These skin substitutes were transplanted for 5 weeks on the backs of immuno-incompetent rats and analyzed. Gene expression and Western blot analyses showed a significantly higher expression of transforming growth factor-β1 by adipose tissue-derived stromal cells compared with dermal Fbs. In addition, we showed that melanocytes responded to the increased levels of transforming growth factor-β1 by down-regulating the expression of key melanogenic enzymes such as tyrosinase. This caused decreased melanin synthesis and, consequently, greatly reduced pigmentation of melDESS. The conclusions are of utmost clinical relevance, namely that adipose tissue-derived stromal cells derived from the hypodermis fail to appropriately interact with epidermal melanocytes, thus preventing the sustainable restoration of the patient's native skin color in bioengineered skin grafts. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Mutation of the Membrane-Associated M1 Protease APM1 Results in Distinct Embryonic and Seedling Developmental Defects in Arabidopsis[C][W

PubMed Central

Peer, Wendy Ann; Hosein, Fazeeda N.; Bandyopadhyay, Anindita; Makam, Srinivas N.; Otegui, Marisa S.; Lee, Gil-Je; Blakeslee, Joshua J.; Cheng, Yan; Titapiwatanakun, Boosaree; Yakubov, Bahktiyor; Bangari, Bharat; Murphy, Angus S.

2009-01-01

Aminopeptidase M1 (APM1), a single copy gene in Arabidopsis thaliana, encodes a metallopeptidase originally identified via its affinity for, and hydrolysis of, the auxin transport inhibitor 1-naphthylphthalamic acid (NPA). Mutations in this gene result in haploinsufficiency. Loss-of-function mutants show irregular, uncoordinated cell divisions throughout embryogenesis, affecting the shape and number of cotyledons and the hypophysis, and is seedling lethal at 5 d after germination due to root growth arrest. Quiescent center and cell cycle markers show no signals in apm1-1 knockdown mutants, and the ground tissue specifiers SHORTROOT and SCARECROW are misexpressed or mislocalized. apm1 mutants have multiple, fused cotyledons and hypocotyls with enlarged epidermal cells with cell adhesion defects. apm1 alleles show defects in gravitropism and auxin transport. Gravistimulation decreases APM1 expression in auxin-accumulating root epidermal cells, and auxin treatment increases expression in the stele. On sucrose gradients, APM1 occurs in unique light membrane fractions. APM1 localizes at the margins of Golgi cisternae, plasma membrane, select multivesicular bodies, tonoplast, dense intravacuolar bodies, and maturing metaxylem cells. APM1 associates with brefeldin A–sensitive endomembrane structures and the plasma membrane in cortical and epidermal cells. The auxin-related phenotypes and mislocalization of auxin efflux proteins in apm1 are consistent with biochemical interactions between APM1 and NPA. PMID:19531600

Severe Acneiform Eruption Induced by Cetuximab (Erbitux®)

PubMed Central

Lee, Jung Eun; Lee, Sang Ju; Lee, Hee Jung; Lee, Ju Hee

2008-01-01

Epidermal growth factor has an important role in the regulation of proliferation and differentiation in epidermal keratinocytes, as well as in the survival, angiogenesis and metastasis of cancer cells. Cetuximab is a chimeric monoclonal antibody selective for the epidermal growth factor receptor that induces a broad range of cellular responses that enhance tumor sensitivity to radiotherapy and chemotherapeutic agents. However, it can cause adverse events in the patient including acneiform eruption, asthenia, abdominal pain and nausea/vomiting. We report a case of severe acneiform eruption induced by cetuximab in a 56-year-old man with colorectal cancer and liver metastases. PMID:18972607

Label-Free Raman Imaging to Monitor Breast Tumor Signatures.

PubMed

Manciu, Felicia S; Ciubuc, John D; Parra, Karla; Manciu, Marian; Bennet, Kevin E; Valenzuela, Paloma; Sundin, Emma M; Durrer, William G; Reza, Luis; Francia, Giulio

2017-08-01

Although not yet ready for clinical application, methods based on Raman spectroscopy have shown significant potential in identifying, characterizing, and discriminating between noncancerous and cancerous specimens. Real-time and accurate medical diagnosis achievable through this vibrational optical method largely benefits from improvements in current technological and software capabilities. Not only is the acquisition of spectral information now possible in milliseconds and analysis of hundreds of thousands of data points achieved in minutes, but Raman spectroscopy also allows simultaneous detection and monitoring of several biological components. Besides demonstrating a significant Raman signature distinction between nontumorigenic (MCF-10A) and tumorigenic (MCF-7) breast epithelial cells, our study demonstrates that Raman can be used as a label-free method to evaluate epidermal growth factor activity in tumor cells. Comparative Raman profiles and images of specimens in the presence or absence of epidermal growth factor show important differences in regions attributed to lipid, protein, and nucleic acid vibrations. The occurrence, which is dependent on the presence of epidermal growth factor, of new Raman features associated with the appearance of phosphothreonine and phosphoserine residues reflects a signal transduction from the membrane to the nucleus, with concomitant modification of DNA/RNA structural characteristics. Parallel Western blotting analysis reveals an epidermal growth factor induction of phosphorylated Akt protein, corroborating the Raman results. The analysis presented in this work is an important step toward Raman-based evaluation of biological activity of epidermal growth factor receptors on the surfaces of breast cancer cells. With the ultimate future goal of clinically implementing Raman-guided techniques for the diagnosis of breast tumors (e.g., with regard to specific receptor activity), the current results just lay the foundation for further label-free optical tools to diagnose the disease.

The receptor tyrosine kinase ERBB4 is expressed in skin keratinocytes and influences epidermal proliferation.

PubMed

Hoesl, Christine; Röhrl, Jennifer M; Schneider, Marlon R; Dahlhoff, Maik

2018-04-01

The epidermal growth factor receptor (EGFR) and associated receptors ERBB2 and ERBB3 are important for skin development and homeostasis. To date, ERBB4 could not be unambiguously identified in the epidermis. The aim of this study was to analyze the ERBB-receptor family with a special focus on ERBB4 in vitro in human keratinocytes and in vivo in human and murine epidermis. We compared the transcript levels of all ERBB-receptors and the seven EGFR-ligands in HaCaT and A431 cells. ERBB-receptor activity was analyzed after epidermal growth factor (EGF) stimulation by Western blot analysis. The location of the receptors was investigated by immunofluorescence in human keratinocytes and skin. Finally, we investigated the function of ERBB4 in the epidermis of skin-specific ERBB4-knockout mice. After EGF stimulation, all ligands were upregulated except for epigen. Expression levels of EGFR were unchanged, but all other ERBB-receptors were down-regulated after EGF stimulation, although all ERBB-receptors were phosphorylated. We detected ERBB4 at mRNA and protein levels in both human epidermal cell lines and in the basal layer of human and murine epidermis. Skin-specific ERBB4-knockout mice revealed a significantly reduced epidermal thickness with a decreased proliferation rate. ERBB4 is expressed in the basal layer of human epidermis and cultured keratinocytes as well as in murine epidermis. Moreover, ERBB4 is phosphorylated in HaCaT cells due to EGF stimulation, and its deletion in murine epidermis affects skin thickness by decreasing proliferation. ERBB4 is expressed in human keratinocytes and plays a role in murine skin homeostasis. Copyright © 2018 Elsevier B.V. All rights reserved.

IFI27, a novel epidermal growth factor-stabilized protein, is functionally involved in proliferation and cell cycling of human epidermal keratinocytes.

PubMed

Hsieh, W-L; Huang, Y-H; Wang, T-M; Ming, Y-C; Tsai, C-N; Pang, J-H S

2015-04-01

IFI27 is highly expressed in psoriatic lesions but its function has not been known. The present study aimed to explore its role in proliferation of epidermal keratinocytes. IFI27 knockdown and over-expression in keratinocytes were used to compare their proliferation, by MTT assay, apoptosis (by annexin V binding) and cell cycle progression by flow cytometry. Formation of cyclin A/CDK1 complex was examined by a co-immunoprecipitaion method. Anti-proliferation effects of IFI27 were also examined in vivo by topical application of IFI27 siRNA on imiquimod-induced psoriatic lesions, in a mouse model. Epidermal growth factor was demonstrated to increase IFI27 expression by prolonging half-life of IFI27 protein. The IFI27 knockdown in keratinocytes reduced the proliferation rate, but had no effect on apoptosis nor on apoptosis-related genes. Interestingly, IFI27 knockdown resulted in S-phase arrest that was found to be associated with increased Tyr15 phosphorylation of CDK1, reduced CDC25B and reduced formation of cyclin A/CDK1 complex. In addition, IFI27 knockdown was also shown to activate p53 by Ser15 phosphorylation and increase p21 expression. Topical application of IFI27 siRNA on imiquimod-induced psoriatic lesion in a mouse model reduced epidermal thickness, formation of rete ridges and PCNA expression. Our study demonstrates for the first time, that cell function of IFI27 is involved in proliferation of skin keratinocytes both in vitro and in vivo. It suggests that IFI27 might be a suitable target for development of a novel anti-psoriasis therapy. © 2015 John Wiley & Sons Ltd.

Live imaging of collagen deposition during skin development and repair in a collagen I - GFP fusion transgenic zebrafish line.

PubMed

Morris, Josephine L; Cross, Stephen J; Lu, Yinhui; Kadler, Karl E; Lu, Yongbo; Dallas, Sarah L; Martin, Paul

2018-06-06

Fibrillar collagen is a major component of many tissues but has been difficult to image in vivo using transgenic approaches because of problems associated with establishing cells and organisms that generate GFP-fusion collagens that can polymerise into functional fibrils. Here we have developed and characterised GFP and mCherry collagen-I fusion zebrafish lines with basal epidermal-specific expression. We use these lines to reveal the dynamic nature of collagen-I fibril deposition beneath the developing embryonic epidermis, as well as the repair of this collagen meshwork following wounding. Transmission electron microscope studies show that these transgenic lines faithfully reproduce the collagen ultrastructure present in wild type larval skin. During skin development we show that collagen I is deposited by basal epidermal cells initially in fine filaments that are largely randomly orientated but are subsequently aligned into a cross-hatch, orthogonal sub-epithelial network by embryonic day 4. Following skin wounding, we see that sub-epidermal collagen is re-established in the denuded domain, initially as randomly orientated wisps that subsequently become bonded to the undamaged collagen and aligned in a way that recapitulates developmental deposition of sub-epidermal collagen. Crossing our GFP-collagen line against one with tdTomato marking basal epidermal cell membranes reveals how much more rapidly wound re-epithelialisation occurs compared to the re-deposition of collagen beneath the healed epidermis. By use of other tissue specific drivers it will be possible to establish zebrafish lines to enable live imaging of collagen deposition and its remodelling in various other organs in health and disease. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Fluctuations of the transcription factor ATML1 generate the pattern of giant cells in the Arabidopsis sepal

PubMed Central

Meyer, Heather M; Teles, José; Formosa-Jordan, Pau; Refahi, Yassin; San-Bento, Rita; Ingram, Gwyneth; Jönsson, Henrik; Locke, James C W; Roeder, Adrienne H K

2017-01-01

Multicellular development produces patterns of specialized cell types. Yet, it is often unclear how individual cells within a field of identical cells initiate the patterning process. Using live imaging, quantitative image analyses and modeling, we show that during Arabidopsis thaliana sepal development, fluctuations in the concentration of the transcription factor ATML1 pattern a field of identical epidermal cells to differentiate into giant cells interspersed between smaller cells. We find that ATML1 is expressed in all epidermal cells. However, its level fluctuates in each of these cells. If ATML1 levels surpass a threshold during the G2 phase of the cell cycle, the cell will likely enter a state of endoreduplication and become giant. Otherwise, the cell divides. Our results demonstrate a fluctuation-driven patterning mechanism for how cell fate decisions can be initiated through a random yet tightly regulated process. DOI: http://dx.doi.org/10.7554/eLife.19131.001 PMID:28145865

The WEREWOLF MYB protein directly regulates CAPRICE transcription during cell fate specification in the Arabidopsis root epidermis.

PubMed

Ryu, Kook Hui; Kang, Yeon Hee; Park, Young-hwan; Hwang, Ildoo; Schiefelbein, John; Lee, Myeong Min

2005-11-01

The Arabidopsis root epidermis is composed of two types of cells, hair cells and non-hair cells, and their fate is determined in a position-dependent manner. WEREWOLF (WER), a R2R3 MYB protein, has been shown genetically to function as a master regulator to control both of the epidermal cell fates. To directly test the proposed role of WER in this system, we examined its subcellular localization and defined its transcriptional activation properties. We show that a WER-GFP fusion protein is functional and accumulates in the nucleus of the N-position cells in the Arabidopsis root epidermis, as expected for a transcriptional regulator. We also find that a modified WER protein with a strong activation domain (WER-VP16) promotes the formation of both epidermal cell types, supporting the view that WER specifies both cell fates. In addition, we used the glucocorticoid receptor (GR) inducible system to show that CPC transcription is regulated directly by WER. Using EMSA, we found two WER-binding sites (WBSs; WBSI and WBSII) in the CPC promoter. WER-WBSI binding was confirmed in vivo using the yeast one-hybrid assay. Binding between the WER protein and both WBSs (WBSI and WBSII), and the importance of the two WBSs in CPC promoter activity were confirmed in Arabidopsis. These results provide experimental support for the proposed role of WER as an activator of gene transcription during the specification of both epidermal cell fates.