Epidermal differentiation

Ivanyi D, Ansink A, Groeneveld E, Hageman PC, Mooi WJ, Heintz AP (1989) New monoclonal antibodies recognizing epidermal differentiation associated keratins in formalin fixed, paraffin embedded tissue. Keratin 10 expression in carcinoma of the vulva. J Pathol 159... 

Hwang M, Kalinin A, and Morasso MI [2005] The temporal and spatial expression of the novel Ca++-binding proteins, Scarf and Scarf2, during development and epidermal differentiation. Gene Expr Patterns 5 801-808... 

Jetten, A. M. 1989. Multistep process of squamous differentiation in tracheobronchial epithelial cells in vitro Analogy with epidermal differentiation. Environ Health Perspect 80 149-160. 

Manabe, M., Sanchez, M., Sun, T. T., and Dale, B. A. (1991). Interaction of filaggrin with keratin filaments during advanced stages of normal human epidermal differentiation and in ichthyosis vulgaris. Differentiation 48, 43-50. 

Harding, C.R., and I.R. Scott. 1983. Histidine-rich proteins (filaggrins) Structural and functional heterogeneity during epidermal differentiation. J Mol Biol 170 651. 

A related gene family is present in the same gene cluster and encodes for proteins containing an S 100-like domain fused to a larger peptide. These proteins include trichohyalin, filaggrin, and repetin, which are multidomain proteins involved in epidermal differentiation (Marenholz et al., 2001 Huber et al., 2005) and are classified as a separate family. 

Huber M, Siegenthaler G, Mirancea N, Marenholz I, Nizetic D, Breitkreutz D, Mischke D, Hohl D. 2005. Isolation and characterization of human repetin, a member of the fused gene family of the epidermal differentiation complex. J Invest Dermatol 124(5) 998-1007. 

Marenholz I, Zirra M, Fischer DF, Backendorf C, Ziegler A, Mischke D. 2001. Identification of human epidermal differentiation complex (EDC)-encoded genes by subtractive hybridization of entire YACs to a gridded keratinocyte cDNA library. Genome Res 11(3) 341—355. 

Lippens, S. et al. Epidermal differentiation does not involve the pro apoptotic executioner caspases, but is associated with caspase-14 induction and processing. Cell Death Differ. 7, 1218, 2000. 

Although the physiological function of IL-20 has not been identified, three lines of evidence support a role for IL-20 and its receptor in inflammatory skin diseases such as psoriasis. For example, overexpression of IL-20 in transgenic mice results in neonatal lethality with skin abnormalities similar to those observed in human psoriatic skin (Bll). These include several hallmark characteristics of this multigenic diseases such as increased proliferation of keratinocytes in the basal and the suprabasal layers of the epidermis, aberrant epidermal differentiation, and infiltration of immune cells into the skin (R3). Recombinant IL-20 protein... 

Forslind, B., Pallon, J., and Werner-Linde, Y., Elemental analysis mirrors epidermal differentiation, Acta Derm. Venereol. (Stockholm), 79, 12, 1999. 

Feingold and his coworkers demonstrated an important role of nuclear hormone receptor on epidermal differentiation and stratum corneum barrier formation. Activation ofPPARa Peroxisome proliferator-activated receptor a by farnesol also stimulated the differentiation of epidermal keratinocytes.42 Cornified envelope formation, involcrin, and transglutaminase protein, and mRNA levels were also increased by the activation of PPARo . Interestingly, the inflammatory response was also inhibited by the treatment.43 They also showed that topical application of PPARo activators accelerated the barrier recovery after tape stripping or acetone treatment and prevented the epidermal hyperplasia induced by repeated barrier disruption.42 Regulation of the nuclear hormone receptor would open a new possibility for improvement of the cutaneous barrier. 

The UV radiation causes premature skin aging. This photo-aging is characterized by wrinkles, mottled pigmentation, dry and rough skin, and loss of skin tone. Use of topical vitamin A derivatives like tretinoin can improve photo-aged skin mainly by changing epidermal differentiation.52 However, skin dryness does not improve and even worsens with retinoid therapy, as well known from its systemic and topical use in several diseases in clinical dermatology. 

Jensen, J.M., Folster-Holst, R., Baranowsky, A., Schunck, M., Winoto-Morbach, S., Neumann, C., Schutze, S., and Proksch, E., Impaired sphingomyelinase activity and epidermal differentiation in atopic dermatitis, J. Invest. Dermatol., 122, 1423-1431, 2004. 

Watkinson, A. Stratum corneum thiol protease (SCTP) a novel cysteine protease of late epidermal differentiation, Arch. Dermatol. Res., 291, 260,1999. 

Two other new nuclear receptors have been shown to increase epidermal differentiation the LXR and the FXR. Farnesol and juvenile hormone activate the FXR leading to improved epidermal differentiation. Two genes encode for the LXR proteins, LXR alpha and LXR beta, and both are activated by various oxysterols the most potent being 22(R)-hydroxycholesterol, 24(S)-hydroxycholesterol, 24(S) 25-epoxycholesterol and 7-hydroxy cholesterol. Cholestenoic acid also acts on this receptor. In vitro these agents also increased epidermal filaggrin levels.129,130... 

Hyaluronan is prominent in the very earliest stage of embryogenesis, in maintenance of the undifferentiated state, with its removal required prior to the onset of differentiation.85 The presence of HA inhibits the process of differentiation, permitting expansion of primordial cell masses. In organotypic cultures of rat keratinocytes, HA suppresses epidermal differentiation,86 must be removed before the program of differentiation can be initiated. 

Passi, A. et al., Hyaluronan suppresses epidermal differentiation in organotypic cultures of rat keratinocytes, Exp. Cell Res., 296, 123, 2004. 

Epidermal Differentiation Process of the Lipid Bilayer from Epidermis to Stratum... 

EPIDERMAL DIFFERENTIATION PROCESS OF THE LIPID BILAYER FROM EPIDERMIS TO STRATUM CORNEUM... 

In addition to participation in epidermal permeability barrier formation, epidermosides are likely associated with autoregulation of epidermal differentiation. Uchida et al. showed that chemically synthesized analogs of epidermosides enhanced keratin synthesis in cultured human keratinocytes... 

Gomar FE, Bernd A, Bereiter-Hahn J, Holzmann H. A new model of epidermal differentiation induction by mechanical stimulation. Arch Dermatol Res. 1990 282 22-32. 

Changes in barrier function due to skin disease generally result either from alteration of the lipid/protein composition of the stratum comeum or from abnormal epidermal differentiation (e.g. in psoriasis). As far as transdermal bioavailability is concerned, however, patches intended for systemic therapy are labelled for application only at normal skin sites, free from dermatologic pathology. 

In skin, l,25-(OH)2D3 inhibits epidermal proliferation and promotes epidermal differentiation. The life cycle of a normal skin cell is about 28 days, compared with 4 days for a psoriatic cell. Sunlight of the UVB range is a known... 

As has been extensively discussed elsewhere (Schurer and Elias, 1991 Wertz, Kremer, and Squier, 1992 Gray et al., 1982), the lipids of the stratum comeum intercellular spaces are unusual in mammalian biology, in that ceramides make up a substantial mole fraction of the total. Furthermore, the final lipid composition of the stratum comeum ilitercellular membranes is considerably different from that found in the intracellular organelles in which these lipids are first synthesized (Squier et al., 1991b Grayson et al., 1985 Wertz et al., 1984), and extensive lipid modifications occur during epidermal differentiation. 

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