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Hair Follicle Keratins
Published in John P. Sundberg, Handbook of Mouse Mutations with Skin and Hair Abnormalities, 2020
George E. Rogers, Barry C. Powell
At present, there is no accepted uniform nomenclature which describes IF keratin chains or the IF associated (matrix) proteins whatever their tissue or species source. The main nomenclature currently used for epidermal IF describes eleven different acidic type I proteins of human epidermal IFs as K9-K19 and eight basic type 11 IF proteins as K1-K8.23 An extension of this nomenclature has been proposed17,24 to make it more flexible and applicable for the addition of new IF proteins to the list. Although there has been insufficient time for the scheme to be discussed for its general acceptance, it is used in the present discussion. Thus, keratin proteins, which by their amino acid sequences belong to the type I class, are given a number after the term KRT1 (abbreviation K1); therefore, in general, K1.n and the members of the type II class are numbered in the general term, K2.n. The epidermal IFs will retain their present numerals but will be allotted to either the K 1 or K2 series, according to whether they are type I or type II, respectively. Therefore, the IF protein currently K1, which is a type II protein, becomes K2.1. In the future, if the nomenclature is accepted, then the assignment of numbers to new members, such as hair IFs, would be done by agreement amongst workers in the field.
Structure and function of skin
Published in Roger L. McMullen, Antioxidants and the Skin, 2018
As implied by their name, keratinocytes synthesize KIFs, which ultimately determine the shape of the cell as it makes its way up the epidermis. At the most fundamental level of KIF structure, two molecules (chains) of alpha-keratin wrap around each other to form a coiled-coil. Two coiled-coils then associate together to form a protofilament. Two protofilaments pair to form one protofibril. Four protofibrils constitute one intermediate filament. There are about thirty different known members of the keratin family—twenty of epithelial origin and ten from hair. Keratins are classified as Type I-acidic (K10-K20) or Type II-basic (K1-K9). Coiled-coils are formed by the pairing of two alpha-keratins, one from each class.
Linear hyperpigmentation
Published in Dimitris Rigopoulos, Alexander C. Katoulis, Hyperpigmentation, 2017
EN arises because of the proliferation of one abnormal population of skin cells, resulting in a localized area of thickened skin. EN is distributed along the lines of Blashko. Skin cells that have the abnormal gene spread out to form the EN. A point mutation in keratin genes is involved in the development of epidermal nevi. Mutations in the FGFR3 gene have been found in approximately 30% of people with a type of nevus in the keratinocytic EN group. The gene mutations involved in most epidermal nevi are unknown. Mutations associated with an EN are present only in the cells of the nevus, not in the normal skin cells surrounding it. Because the mutation is found in some of the body’s cells, but not in others, people with an EN are said to be mosaic for the mutation. Keratin 1 and keratin 10 gene abnormalities have been found in parents who have an epidermolytic EN and in their offspring who have a bullous ichthyosiform erythroderma.22
B-Raf inhibitor vemurafenib counteracts sulfur mustard-induced epidermal impairment through MAPK/ERK signaling
Published in Drug and Chemical Toxicology, 2023
Zhiyong Xiao, Feng Liu, Junping Cheng, Ying Wang, Wenxia Zhou, Yongxiang Zhang
In a previous study, activation of ERK1/2 was observed after SM exposure; however, its role in SM injury and tissue repair has not been precisely defined. SM affects the skin’s regeneration capacity by stimulating the expression of the premature differentiation-specific markers keratin-1, involucrin, and loricrin in keratinocytes (Rosenthal et al.1998). Meanwhile, the blockage of ERK1/2 by PD98059 facilitated SM-promoted expression of diverse differentiation markers, suggesting that ERK1/2 acts as a negative modulator of skin keratosis. In contrast, p38 expression abrogation had the inverse effect on ERK, as evident from the reduced expression of differentiation markers in SM-treated cells (Popp et al.2011). After exposure to SM, patients frequently present with hyperkeratosis, characterized by overproduction of keratins (Naraghi et al.2005). In our study, the therapeutic effect of vemurafenib on HaCaT cell survival against SM was ERK1/2-dependent, as ERK1/2 blockade abolished vemurafenib-induced cellular protection (Figure 4). The beneficial role of ERK1/2 in promoting cell survival and preventing hyperkeratosis in the context of SM exposure suggests that in contrast to inflammation-elicited MAPKs, typically p38, constitutionally expressed ERK1/2 is more likely to participate in maintaining and restoring cell homeostasis in the cutaneous tissue. These ambiguous results indicate a complex and yet unclear role of ERK1/2 in skin tissue damage and repair (Figure 6).
Higher degree of keratinization correlated with severe bone destruction in acquired Cholesteatoma
Published in Acta Oto-Laryngologica, 2023
Yisi Feng, Zhuohao Li, Wuhui He, Ying Xiong, Yu Si, Zhigang Zhang
According to the latest evidence-based consensus statements of the European Academy of Otology and Neurotology (EAONO), cholesteatoma is a mass composed of keratinized squamous epithelium, connective tissue and the progressive accumulation of keratin debris with/without inflammation [2]. Ectopic keratinized squamous epithelium is considered to be the primary pathological change. Keratinized squamous epithelium is composed of stratum corneum and keratinocytes with different states of differentiation, which can be recognized by keratin (K) expression. Keratin is not only the main constituent protein of epithelial cell intermediate filaments but also participates in cell growth, migration, and differentiation; thus, it can be used as a marker of keratinization [3]. Recent studies have shown that keratins such as K1, K5, K10 and K14, which represent keratinocytes with proliferation and differentiation abilities, were upregulated in cholesteatoma and involved in the pathogenesis of cholesteatoma [4,5]. In cholesteatoma, keratinocyte was the predominant cell type in which researchers have shown increased interest. However, whether the degree of bone destruction is related to the degree of keratinization is still unconfirmed.
Portulaca oleracea extract relieves skin barrier damage induced by increased photosensitivity after GA peeling
Published in Cutaneous and Ocular Toxicology, 2022
Jing Wei, Qianghua Quan, Peiyu Wang, Yiming Wang, Tong Huo, Quan An
Modern studies have revealed that P. oleracea extract is capable of regulating the TNF-α-induced NF-κB signalling pathway as well as suppressing the overexpression of pro-inflammatory factors25. Zhao et al.26 reported that with the use of a cream containing calcipotriol ointment and P. oleracea extract for four consecutive weeks, the protein expression levels of Keratin 10 (K10), loricrin (LOR), and FLG were significantly downregulated in psoriatic lesions and TEWL values were significantly decreased. Keratins are the major proteins in the epidermis. They build the intermediate filament (IF) cytoskeleton, which provides epidermal stability because they are highly crosslinked with the cornified envelope. Keratin 1 (K1) and K10 are among the first keratins to be expressed during cornification27. LOR is synthesized and subsequently crosslinked by several transglutaminases to reinforce epidermal stability28. These studies have shown that P. oleracea has effects on inhibiting inflammation and repairing the skin barrier. Our research also confirmed that P. oleracea can relieve damage to the skin barrier and inflammation induced by GA + UVB.