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John Schiefelbein - One of the best experts on this subject based on the ideXlab platform.

  • the gene regulatory network for root Epidermal Cell type pattern formation in arabidopsis
    Journal of Experimental Botany, 2009
    Co-Authors: John Schiefelbein, Su Hwan Kwak, Yana Wieckowski, Christa Barron, Angela Bruex
    Abstract:

    A fundamental aspect of multiCellular development is the patterning of distinct Cell types in appropriate locations. In this review, the molecular genetic control of Cell-type pattern formation in the root epidermis of Arabidopsis thaliana is summarized. This developmental system represents a simple and genetically tractable example of plant Cell patterning. The distribution of the two Epidermal Cell types, root-hair Cells and non-hair Cells, are generated by a combination of positional signalling and lateral inhibition mechanisms. In addition, recent evidence suggests that reinforcing mechanisms are used to ensure that the initial Cell fate choice is adopted in a robust manner.

  • the werewolf myb protein directly regulates caprice transcription during Cell fate specification in the arabidopsis root epidermis
    Development, 2005
    Co-Authors: Kook Hui Ryu, John Schiefelbein, Yeon Hee Kang, Young Hwan Park, Ildoo Hwang, Myeong Min Lee
    Abstract:

    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.

  • the bhlh genes glabra3 gl3 and enhancer of glabra3 egl3 specify Epidermal Cell fate in the arabidopsis root
    Development, 2003
    Co-Authors: Christine Bernhardt, Alan M Lloyd, Myeong Min Lee, Antonio Gonzalez, Fan Zhang, John Schiefelbein
    Abstract:

    The position-dependent specification of the hair and non-hair Cell types in the Arabidopsis root epidermis provides a simple model for the study of Cell fate determination in plants. Several putative transcriptional regulators are known to influence this Cell fate decision. Indirect evidence from studies with the maize R gene has been used to suggest that a bHLH transcription factor also participates in this process. We show that two Arabidopsis genes encoding bHLH proteins, GLABRA3 (GL3) and ENHANCER OF GLABRA3 (EGL3), act in a partially redundant manner to specify root Epidermal Cell fates. Plants homozygous for mutations in both genes fail to specify the non-hair Cell type, whereas plants overexpressing either gene produce ectopic non-hair Cells. We also find that these genes are required for appropriate transcription of the non-hair specification gene GL2 and the hair Cell specification gene CPC, showing that GL3 and EGL3 influence both Epidermal Cell fates. Furthermore, we show that these bHLH proteins require a functional WER MYB protein for their action, and they physically interact with WER and CPC in the yeast two-hybrid assay. These results suggest a model in which GL3 and EGL3 act together with WER in the N Cell position to promote the non-hair Cell fate, whereas they interact with the incomplete MYB protein CPC in the H position, which blocks the non-hair pathway and leads to the hair Cell fate.

  • werewolf a myb related protein in arabidopsis is a position dependent regulator of Epidermal Cell patterning
    Cell, 1999
    Co-Authors: John Schiefelbein
    Abstract:

    Abstract 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.

  • the ttg gene is required to specify Epidermal Cell fate and Cell patterning in the arabidopsis root
    Developmental Biology, 1994
    Co-Authors: Moira E Galway, James D Masucci, Alan M Lloyd, Virginia Walbot, Ronald W Davis, John Schiefelbein
    Abstract:

    The control of Cell fate was investigated in the root epidermis of Arabidopsis thaliana. Two distinct types of differentiated Epidermal Cells are normally present: root-hair-bearing Cells and hairless Cells. In wild-type Arabidopsis roots, Epidermal Cell fate was found to be correlated with Cell position, with root-hair Cells located over radial walls between cortical Cells, and with hairless Cells located directly over cortical Cells. This normal positional relationship was absent in ttg (transparent testa glabrous) mutants (lacking trichomes, anthocyanins, and seed coat mucilage); Epidermal Cells in all positions differentiate into root-hair Cells. The opposite condition was generated in roots of transgenic Arabidopsis expressing the maize R (R-Lc) gene product (a putative TTG homologue) under the control of a strong promoter (CaMV35S), which produced hairless Epidermal Cells in all positions. In both the ttg and R-expressing roots, Epidermal Cell differentiation was affected at an early stage, prior to the onset of Cell elongation or root-hair formation. The ttg mutations were also associated with abnormalities in the morphology and organization of Cells within and surrounding the root apical meristem. The results indicate that alterations in TTG activity cause developing Epidermal Cells to misinterpret their position and differentiate into inappropriate Cell types. This suggests that, in wild-type roots, TTG provides, or responds to, positional signals to cause differentiating Epidermal Cells that lie over cortical Cells to adopt a hairless Cell fate.

Ramesh Kumar - One of the best experts on this subject based on the ideXlab platform.

  • comparison between autologous noncultured extracted hair follicle outer root sheath Cell suspension and autologous noncultured Epidermal Cell suspension in the treatment of stable vitiligo a randomized study
    British Journal of Dermatology, 2013
    Co-Authors: C Singh, Sunil Dogra, Davinder Parsad, A J Kanwar, Ramesh Kumar
    Abstract:

    Summary Background Vitiligo is an acquired disorder of pigmentation caused by loss of Epidermal melanocytes. Autologous noncultured Epidermal Cell suspension (NCES) and autologous noncultured extracted hair follicle outer root sheath Cell suspension (NCORSHFS) are important surgical modalities for the treatment of stable vitiligo. Objectives To compare NCES and NCORSHFS for producing repigmentation in stable vitiligo. Methods We randomized 30 patients with 47 stable vitiligo lesions into two groups. Patients in group 1 were treated with NCES, and those in group 2 with NCORSHFS. They were evaluated 16 weeks postsurgery for the extent of repigmentation, colour match, change in Dermatology Life Quality Index (DLQI) score and patient satisfaction. Results The extent of repigmentation was exCellent (90–100% repigmentation) in 83% of lesions in the NCES group and 65% of lesions in the NCORSHFS group (P = 0·154). Repigmentation ≥ 75% (good repigmentation) was observed in 92% of lesions in the NCES group and 78% of lesions in the NCORSHFS group (P = 0·425). There was a significant improvement in DLQI score in both the groups, but the mean decrease among groups did not differ significantly (P = 0·244). However, patients in the NCES group were significantly more satisfied than the patients in the NCORSHFS group. No significant difference was seen in colour match and pattern of repigmentation. Adverse effects were minimal. Conclusions Both NCES and NCORSHFS are safe and effective techniques with comparable efficacy. To the best of our knowledge, this is the first study directly comparing two different Cellular techniques.

Catherine Jackson - One of the best experts on this subject based on the ideXlab platform.

  • stem Cell function is conserved during short term storage of cultured Epidermal Cell sheets at 12 c
    PLOS ONE, 2020
    Co-Authors: Hakon Ringstad, Sjur Reppe, Tine Hiorth Schoyen, Kim Alexander Tonseth, Tor Paaske Utheim, Catherine Jackson
    Abstract:

    Transplantation of cultured Epidermal Cell sheets (CES) can be life-saving for patients with large area burns. CES have also been successfully used to regenerate eye and urethral epithelia in animal models. Short-term storage aims to extend the transplantation window, offers flexibility in timing surgery and allows testing of CES quality, phenotype and sterility. This study investigated extended CES storage and explored the effect of additional re-incubation recovery time following storage. The proliferative quality of stored confluent versus pre-confluent CES was also investigated using functional testing. CES were stored at 12°C and results compared to non-stored control CES. Investigation of timepoints during 15 days storage revealed that viability began to deteriorate by day 11 and was associated with increased lactate in the storage medium. The percentage of apoptotic Cells also significantly increased by day 11. Flow cytometry analysis of integrin β1 expression and Cell size indicated best retention of stem Cells at 7 days of storage. Functional testing of pre-confluent and confluent Cells following 7 days storage showed that pre-confluent Cells responded well to 1-day re-incubation after storage; they became highly prolific, increasing in number by ~67%. Conversely, proliferation in stored confluent Cells declined by ~50% with 1-day re-incubation. Pre-confluent stored CES also had far superior stem Cell colony forming efficiency (CFE) performance compared to the confluent group. Re-incubation improved CFE in both groups, but the pre-confluent group again out-performed the confluent group with significantly more colonies. In conclusion, a maximum storage period of 7 days is recommended. Use of pre-confluent Cells and one day recovery incubation greatly improves viability, colony-forming ability and proliferation of Cells stored for 7 days at 12°C. Thus, these recommendations should be considered under culture and storage of high-quality CES for clinical use.

Fiona M Watt - One of the best experts on this subject based on the ideXlab platform.

  • differential sensitivity of Epidermal Cell subpopulations to beta catenin induced ectopic hair follicle formation
    Developmental Biology, 2010
    Co-Authors: Christopher M Baker, Annemieke Verstuyf, Kim B Jensen, Fiona M Watt
    Abstract:

    Wnt signalling is required for hair follicle development and for the growth phase (anagen) of postnatal follicles. When the pathway is activated at high levels in adult mouse epidermis, ectopic follicles form from existing follicles, interfollicular epidermis (IFE) and sebaceous glands, revealing a remarkable ability of the tissue to be reprogrammed. To compare the competence of different Epidermal Cell populations to form ectopic follicles, we expressed a 4-hydroxy-tamoxifen (4OHT) inducible, stabilised β-catenin transgene (ΔNβ-cateninER) under the control of two different promoters. We targeted the reservoir of stem Cells in the hair follicle bulge via the keratin 15 (K15) promoter and targeted the sebaceous glands and base of the follicle (bulb) with a truncated K5 promoter (ΔK5). No ectopic follicles formed in the IFE in either model, establishing the autonomy of the IFE stem Cell compartment in undamaged epidermis. Activation of β-catenin in the bulge stimulated proliferation and bulge expansion. Existing hair follicles entered anagen, but no ectopic follicles formed. ΔK5ΔNβ-cateninER expressing hair follicles also entered anagen on 4OHT treatment. In addition, a subpopulation of Cells at the base of the sebaceous gland readily formed ectopic follicles, resulting in complete and reversible conversion of sebaceous glands into hair follicles. Combined activation of β-catenin and the vitamin D receptor enhanced differentiation of sebaceous gland-derived hair follicles and stimulated ectopic follicle formation in the hair follicle bulb, but not in the bulge. Our results suggest that the bulge and sebaceous gland are, respectively, non-permissive and permissive niches for Wnt induced hair follicle differentiation.

Margret Sauter - One of the best experts on this subject based on the ideXlab platform.

  • emerging roots alter Epidermal Cell fate through mechanical and reactive oxygen species signaling
    The Plant Cell, 2012
    Co-Authors: Bianka Steffens, Alexander Kovalev, Stanislav N. Gorb, Margret Sauter
    Abstract:

    A central question in biology is how spatial information is conveyed to locally establish a developmental program. Rice (Oryza sativa) can survive flash floods by the emergence of adventitious roots from the stem. Epidermal Cells that overlie adventitious root primordia undergo Cell death to facilitate root emergence. Root growth and Epidermal Cell death are both controlled by ethylene. This study aimed to identify the signal responsible for the spatial control of Cell death. Epidermal Cell death correlated with the proximity to root primordia in wild-type and ADVENTITIOUS ROOTLESS1 plants, indicating that the root emits a spatial signal. Ethylene-induced root growth generated a mechanical force of ∼18 millinewtons within 1 h. Force application to Epidermal Cells above root primordia caused Cell death in a dose-dependent manner and was inhibited by 1-methylcyclopropene or diphenylene iodonium, an inhibitor of NADPH oxidase. Exposure of Epidermal Cells not overlying a root to either force and ethylene or force and the catalase inhibitor aminotriazole induced ectopic Cell death. Genetic downregulation of the reactive oxygen species (ROS) scavenger METALLOTHIONEIN2b likewise promoted force-induced ectopic Cell death. Hence, reprogramming of Epidermal Cell fate by the volatile plant hormone ethylene requires two signals: mechanosensing for spatial resolution and ROS for Cell death signaling.

  • ethylene induces Epidermal Cell death at the site of adventitious root emergence in rice
    Plant Physiology, 2000
    Co-Authors: Heidi Mergemann, Margret Sauter
    Abstract:

    In deepwater rice (Oryza sativa), adventitious root primordia initiate at the nodes as part of normal development. Emergence of the roots is dependent on flooding of the plant and is mediated by ethylene action. Root growth was preceded by the induced death of Epidermal Cells of the node external to the tip of the root primordium. Cell death proceeded until the epidermis split open. Through this crack the root eventually emerged. Induced death was confined to nodal Epidermal Cells covering the tip of the primordia. Our results suggest that this process facilitates adventitious root emergence and prevents injury to the growing root. Cell death was inducible not only by submergence but also by application of 1-aminocyclopropane-1-carboxylic acid, the natural precursor of ethylene and it was suppressed in the presence of 2,5-norbornadiene (bicyclo[2.2.1]hepta-2,5-diene), an inhibitor of ethylene action. Adventitious root growth and Epidermal Cell death are therefore linked to the ethylene signaling pathway, which is activated in response to low oxygen stress.