Disease relevance of urocanic acid

• Based on (a) the close fit of its absorption spectrum to the action spectrum, (b) its superficial location in the stratum corneum, and (c) its photochemical properties, the hypothesis is advanced that the photoreceptor for systemic UV-induced immunosuppression of contact hypersensitivity may be urocanic acid [1].
• The photochemistry of Urocanic acid, a chromophore present in human skin and linked to photoimmunosuppression and skin cancer, is investigated theoretically by means of time-dependent density functional theory [2].
• In this study, the efferent suppression of delayed-type hypersensitivity by UV-irradiated urocanic acid is demonstrated to be due to 2 phenotypically distinct T cells, (Thy1+, L3T4-, Ly2+) and (Thy1+, L3T4+, Ly2-) [3].
• Two phenotypically distinct T cells are involved in ultraviolet-irradiated urocanic acid-induced suppression of the efferent delayed-type hypersensitivity response to herpes simplex virus, type 1 in vivo [3].
• This situation parallels the generation of 2 distinct T-suppressor cells for HSV-1 by UV irradiation of mice and provides further evidence for the involvement of urocanic acid in the generation of UVB suppression [3].

High impact information on urocanic acid

• Urocanic acid enhances IL-10 production in activated CD4+ T cells [4].
• Regulation of tumor antigen presentation by urocanic acid [5].
• Histidase (histidine ammonia-lyase, EC 4.3.1.3) catalyzes the deamination of histidine to urocanic acid [6].
• It is concluded that the imidazoleacrylic acid antagonists share some interactions in TM-VII of the AT1 receptor with the biphenylimidazole antagonists, but the binding of the imidazoleacrylic acid compounds is uniquely dependent on His256 in TM-VI, possibly through the carboxyphenyl moiety [7].
• Singlet oxygen luminescence of urocanic acid was clearly detected but the signal was too weak to quantify a quantum yield [8].

Chemical compound and disease context of urocanic acid

• These results suggest that L-histidine and/or urocanic acid induce a hypercholesterolemia which disappears several days after the supplementation ceases [9].
• Ultraviolet irradiated urocanic acid (4-imidazoleacrylic acid) containing a mixture of cis- and trans-isomers has been shown previously to induce suppression of the delayed type hypersensitivity (DTH) response to Herpes simplex virus type 1 (HSV-1) in a murine model of infection [10].

Biological context of urocanic acid

• Poly(4-vinylimidazole) (P4V) was obtained by free radical polymerization of 4-vinylimidazole (4V) prepared by decarboxylation of urocanic acid [11].
• In the other cross, the transductants were urocanase-less mutants having both phenotypes of the donor, and most produced high concentrations (10.5 mg/ml) of urocanic acid [12].
• Urocanic acid photobiology. Photooxidation and superoxide formation [13].
• Direct comparison of DNA damage, isomerization of urocanic acid and edema in the mouse produced by three commonly used artificial UV light sources [14].
• Seasonal variation in urocanic acid isomers in human skin [15].

Anatomical context of urocanic acid

• Effect of phototherapy and urocanic acid isomers on natural killer cell function [16].
• The putative receptor in skin for the primary event in UV-suppression is urocanic acid (UCA) which may then interact locally, or systemically, with antigen presenting cells or initiate a cascade of events resulting in suppression [17].
• Early cellular and molecular events in inflamed skin include the active participation of epidermal keratinocytes (KCs) and dermal mast cells which can produce diffusible mediators such as tumor necrosis factor-alpha (TNF-alpha), histamine, and urocanic acid (UCA) [18].
• Histidinemia (MIM235800) is characterized by elevated histidine in body fluids and decreased urocanic acid in blood and skin and results from histidase (histidine ammonia lyase, EC 4.3.1.3) deficiency [19].
• Their effects on the photoisomerization of the naturally occurring trans-isomer of urocanic acid (UCA) to cis-UCA, on the density of Langerhans cells and on the ability of epidermal cells to stimulate allogeneic lymphocytes in the mixed skin lymphocyte reaction (MSLR) were ascertained [20].

Associations of urocanic acid with other chemical compounds

• A deamination product of histidine, urocanic acid, accumulates in the skin of mammals as trans-urocanic acid [21].
• This includes photodynamic effects, menadione-mediated photooxidation, photoionization of antibiotics, the photochemistry of 5-halogenopyrimidines and urocanic acid [22].
• Urocanic acid photobiology. Photocycloaddition of N,N-dimethylthymine to urocanic acid [23].
• Urinary urocanic acid level thus appears as a very sensitive indicator of liver malfunction, in a manner similar to low plasma prealbumin and/or high A-alpha 1-gamma-glutamyltranspeptidase values [24].
• The urocanic acid cis isomer (cis-UCA) is a possible cutaneous photoreceptor for the immunomodulatory phenomena that follow ultraviolet B irradiation [25].

Gene context of urocanic acid

• Enhancement of riboflavin-mediated photo-oxidation of glucose 6-phosphate dehydrogenase by urocanic acid [26].
• Based on the excretion of urocanic acid it is estimated that NEUT2 mice catabolize approximately 40 micromol/day via the deamination pathway [27].
• Incubation of urocanase from Pseudomonas putida with either its substrate, urocanic acid, or product, 4'(5')-imidazolone-5'(4')-propionic acid, resulted in an oxygen-dependent inhibition of enzyme activity [28].
• While distinct molecular requirements exist for biphenylimidazole and imidazoleacrylic acid binding, these results suggest that Val108 is a common structural determinant of nonpeptide recognition on the AT1 receptor [29].
• The presence of urocanic acid in the skin suggests that significant degradation of ADR could occur in the presence of biologically relevant concentrations of riboflavin if patients treated with ADR are exposed to sunlight [30].

Analytical, diagnostic and therapeutic context of urocanic acid

• Interference-based electrochemical biosensor for the measurement of the concentration and isomer ratio of urocanic acid [31].
• Analysis of Z and E isomers of urocanic acid by high-performance liquid chromatography [32].
• A non-invasive chamber sampling technique for HPLC analysis of human epidermal urocanic acid isomers [33].
• Effect of psoriasis heliotherapy on epidermal urocanic acid isomer concentrations [34].
• Thus, the quantification of skin urocanic acid was considered to be simple and useful for confirming the diagnosis of histidinemia, especially in a neonatal mass-screening program [35].

References