Epigenetic control of skin differentiation genes by phytocannabinoids

Abstract

BACKGROUND AND PURPOSEEndocannabinoid signalling has been shown to have a role in the control of epidermal physiology, whereby anandamide is able to regulate the expression of skin differentiation genes through DNA methylation. Here, we investigated the possible epigenetic regulation of these genes by several phytocannabinoids, plant-derived cannabinoids that have the potential to be novel therapeutics for various human diseases. EXPERIMENTAL APPROACHThe effects of cannabidiol, cannabigerol and cannabidivarin on the expression of skin differentiation genes keratins 1 and 10, involucrin and transglutaminase 5, as well as on DNA methylation of keratin 10 gene, were investigated in human keratinocytes (HaCaT cells). The effects of these phytocannabinoids on global DNA methylation and the activity and expression of four major DNA methyltransferases (DNMT1, 3a, 3b and 3L) were also examined. KEY RESULTSCannabidiol and cannabigerol significantly reduced the expression of all the genes tested in differentiated HaCaT cells, by increasing DNA methylation of keratin 10 gene, but cannabidivarin was ineffective. Remarkably, cannabidiol reduced keratin 10 mRNA through a type-1 cannabinoid (CB1) receptor-dependent mechanism, whereas cannabigerol did not affect either CB1 or CB2 receptors of HaCaT cells. In addition, cannabidiol, but not cannabigerol, increased global DNA methylation levels by selectively enhancing DNMT1 expression, without affecting DNMT 3a, 3b or 3L. CONCLUSIONS AND IMPLICATIONSThese findings show that the phytocannabinoids cannabidiol and cannabigerol are transcriptional repressors that can control cell proliferation and differentiation. This indicates that they (especially cannabidiol) have the potential to be lead compounds for the development of novel therapeutics for skin diseases. AbbreviationsAEA, anandamide; 2-AG, 2-arachidonoylglycerol; CB1, cannabinoid receptor type I; CB2, cannabinoid receptor type II; CBD, cannabidiol; CBDV, cannabidivarin; CBG, cannabigerol; CPZ, capsazepine; DAGL, diacylglycerol lipase; DNMT, DNA methyltransferase; eCBs, endocannabinoids; ECS, endocannabinoid system; FAAH, fatty acid amide hydrolase; K1, keratin 1; K10, keratin 10; NAPE-PLD, N-acyl-phosphatidylethanolamines-specific phospholipase D; NHEK, normal human epidermal keratinocytes; MAGL, monoacylglycerol lipase; SR141716, N-piperidino-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-3-pyrazole carboxamide; SR144528, N-[(1)-endo-1,3,3-trimethy-1-bicyclo [2.2.1]-heptan-2-yl]5-(4-chloro-3-methyl-phenyl)-1-(4-methyl-benzyl)-pyrazole-3-carboxamide; TGase 5, transglutaminase 5; THC, Δ 9-tetrahydrocannbinol; TPA, 12-O-tetradecanoylphorbol 13-acetate; TRPV1, transient receptor potential vanilloid 1 IntroductionEndocannabinoids (eCBs) are lipid mediators derived from membrane precursors and are involved in multiple regulatory functions, both in health and disease (Di Marzo and Petrosino, 2007). The two most important eCBs are N-arachidonylethanolamine ('anandamide', AEA) and 2-arachidonoylglycerol (2-AG) that elicit their a...

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