Epidermis (botany)

About: Epidermis (botany) is a research topic. Over the lifetime, 7254 publications have been published within this topic receiving 308153 citations.

Lgr6 Marks Stem Cells in the Hair Follicle That Generate All Cell Lineages of the Skin

Abstract: Mammalian epidermis consists of three self-renewing compartments: the hair follicle, the sebaceous gland, and the interfollicular epidermis. We generated knock-in alleles of murine Lgr6, a close relative of the Lgr5 stem cell gene. Lgr6 was expressed in the earliest embryonic hair placodes. In adult hair follicles, Lgr6+ cells resided in a previously uncharacterized region directly above the follicle bulge. They expressed none of the known bulge stem cell markers. Prenatal Lgr6+ cells established the hair follicle, sebaceous gland, and interfollicular epidermis. Postnatally, Lgr6+ cells generated sebaceous gland and interfollicular epidermis, whereas contribution to hair lineages gradually diminished with age. Adult Lgr6+ cells executed long-term wound repair, including the formation of new hair follicles. We conclude that Lgr6 marks the most primitive epidermal stem cell.

Epidermal Differentiation: The Bare Essentials

Abstract: N the past ten years, there have been a number of major scientific discoveries in the field of epidermal differentiation. We owe many of these findings to the development of model tissue culture systems, and to technological advances in molecular biology. In this article, I will review some important aspects of the biology of terminal differentiation in vivo and in vitro, and highlight the recent advances in elucidating the molecular mechanism underlying these processes.

p63 is the molecular switch for initiation of an epithelial stratification program

Abstract: Development of stratified epithelia, such as the epidermis, requires p63 expression. The p63 gene encodes isoforms that contain (TA) or lack (ΔN) a transactivation domain. We demonstrate that TAp63 isoforms are the first to be expressed during embryogenesis and are required for initiation of epithelial stratification. In addition, TAp63 isoforms inhibit terminal differentiation, suggesting that TAp63 isoforms must be counterbalanced by ΔNp63 isoforms to allow cells to respond to signals required for maturation of embryonic epidermis. Our data demonstrate that p63 plays a dual role: initiating epithelial stratification during development and maintaining proliferative potential of basal keratinocytes in mature epidermis.

Immunologic functions of Ia-bearing epidermal Langerhans cells

Abstract: Langerhans cells (LC) constitute a morphologically well-characterized minor subpopulation of the mammalian epidermis whose functional role is still a matter of conjecture. The hypothesis that LC represent an epidermal equivalent to cells of the monocyte-macrophage-histiocyte series is supported by the recent observations that in humans and guinea pigs LC are the only epidermal cells that express Fc-IgG receptors, C3 receptors, and Ia antigens. Using inbred strain 2 and strain 13 guinea pigs, we investigated in this study whether LC can mediate the same immunologic functions as Ia-bearing macrophages. LC-enriched and LC-depleted epidermal cells were prepared by separation of Fc-IgG rosetting epidermal cells on density gradients. When both populations were tested for the biosynthesis of alloantigens by immunoprecipitation techniques, Ia antigen synthesis was restricted to the LC-enriched fraction. Functional studies demonstrated that antigen-pulsed LC-enriched epidermal cells induce a proliferative response in immune T cells that is comparable in magnitude to that seen with macrophages. Moreover, effective presentation of immunologically relevant antigen requires syngeneity between LC-enriched epidermal cells and responder lymphocytes. In the mixed leukocyte reaction (MLR), LC-enriched epidermal cells were as effective stimulators as macrophages. LC-depleted epidermal cells, by contrast, induced little or no stimulation in both assay systems. Both the antigen-presenting and the MLR-stimulatory capacities of LC-enriched epidermal cells could be abrogated by pretreatment with anti-Ia sera and complement. The presence in the epidermis of Ia-bearing LC, capable of mediating the immunologic functions of Ia-bearing macrophages, has important clinical implications with regard to the role of LC as sensitizing cells in both contact hypersensitivity and skin graft rejection.

Rice plants take up iron as an Fe3+-phytosiderophore and as Fe2+.

Abstract: Summary Only graminaceous monocots possess the Strategy II iron (Fe)-uptake system in which Fe is absorbed by roots as an Fe3+-phytosiderophore. In spite of being a Strategy II plant, however, rice (Oryza sativa) contains the previously identified Fe2+ transporter OsIRT1. In this study, we isolated the OsIRT2 gene from rice, which is highly homologous to OsIRT1. Real-time PCR analysis revealed that OsIRT1 and OsIRT2 are expressed predominantly in roots, and these transporters are induced by low-Fe conditions. When expressed in yeast (Saccharomyces cerevisiae) cells, OsIRT2 cDNA reversed the growth defects of a yeast Fe-uptake mutant. This was similar to the effect of OsIRT1 cDNA. OsIRT1– and OsIRT2–green fluorescent protein fusion proteins localized to the plasma membrane when transiently expressed in onion (Allium cepa L.) epidermal cells. OsIRT1 promoter–GUS analysis revealed that OsIRT1 is expressed in the epidermis and exodermis of the elongating zone and in the inner layer of the cortex of the mature zone of Fe-deficient roots. OsIRT1 expression was also detected in the ccompanion cells. Analysis using the positron-emitting tracer imaging system showed that rice plants are able to take up both an Fe3+-phytosiderophore and Fe2+. This result indicates that, in addition to absorbing an Fe3+-phytosiderophore, rice possesses a novel Fe-uptake system that directly absorbs the Fe2+, a strategy that is advantageous for growth in submerged conditions.