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Collodion baby and harlequin ichthyosis
Published in Biju Vasudevan, Rajesh Verma, Dermatological Emergencies, 2019
D. V. Lakshmi, Sahana M. Srinivas
TGM1 is an enzyme responsible for cross-linking proteins in the cornified cell envelope, and lipoxygenases are a group of dioxygenase enzymes involved in lipid metabolism of lamellar granules or intercellular lipid lamellae in epidermis. Different combinations of TGM1 mutations causing phenotypic variations with respect to severity have also been reported [5]. Ichthyin acts as a receptor for the hepoxilin pathway that leads to abnormalities of the granular layer of the epidermis and abnormal lamellar granules [8]. In a self-healing collodion membrane, compound heterozygous transglutaminase mutation ALOXE3 and ALOX12B genes have been found [10].
Introduction to Human Cytochrome P450 Superfamily
Published in Shufeng Zhou, Cytochrome P450 2D6, 2018
This gene includes 12 coding exons and the cDNA spans 2.6 kb in length. All CYP4F22 mutations reported to date are predicted to abolish the function of the encoded CYP protein and to compromise the 12R-lipoxygenase (hepoxilin) pathway. 12R-lipoxygenase is expressed only in the epidermis and the tonsils and is upregulated in psoriatic lesions. It transforms 20:4n-6 to 12R-HPETE, which is important for the development of the water permeability barrier function in the epidermis. CYP4F22 catalyzes the ω-3 hydroxylation of 20:4n-6; however, oxygenation of 8R,11R,12R-HETE is not observed (Nilsson et al. 2010). An additional function of CYP4F22 is to synthesize the ω-hydroxy fatty acids in the ceramide. Mutations in the CYP4F22 gene have been linked to lamellar ichthyosis (Kelly et al. 2011; Rodriguez-Pazos et al. 2011; Sugiura et al. 2013). CYP4F22 is involved in the metabolism of lipid substrates that are important to differentiation/keratinization of epidermal keratinocytes, at least during the fetal period (Sasaki et al. 2012).
Physiological and pathophysiological roles of hepoxilins and their analogs
Published in Drug Metabolism Reviews, 2023
Sara A. Helal, Fadumo Ahmed Isse, Samar H. Gerges, Ayman O. S. El-Kadi
Hepoxilins are AA metabolites that are involved in several biological processes. They have beneficial effects on the skin, especially on the proliferation and differentiation of epithelial cells. They also possess pro-inflammatory effects and play a significant role in neutrophil activation and migration to the site of infection or inflammation. Moreover, they demonstrated anti-apoptotic effects, especially on RINm5F cells. Additionally, they participate in the volume regulation of intact human platelets. HX analogs, PBTs, can have some antagonistic effects compared to natural HXs. They demonstrated anti-cancer, anti-inflammatory, and anti-thrombotic actions. Accordingly, we believe that HXs and their analogs are candidates for further research to investigate their physiological effects on other organs such as the heart, kidney, and liver, as well as their potential therapeutic applications.