Mechanism of Catechol-O-methyltransferase Regulating Orofacial Pain Induced by Tooth Movement.

OBJECTIVE: To explore the mechanism of catechol-O-methyltransferase (COMT) in tooth movement pain. METHODS: The experimental groups were randomly allocated into the healthy control, sham operation, model, model+shCOMT experimental, model+shCOMT control, and model+COMT antagonist groups. A tooth movement pain model was established. The pain stimulation and behavior test were performed. The duration of grooming behavior was determined. The appropriate experimental force and duration for application were selected. COMT shRNA vector was constructed and packaged as adenovirus. The shCOMT adenovirus was injected into the left infraorbital foramen. Seven days later, the trigeminal ganglia of all treatment groups were obtained. The COMT and IL-17 expressions were detected by western blot. The appropriate COMT antagonist concentration was selected. The pathological results of each group were detected by HE staining. The tooth movement distance was determined. The COMT gene expression was detected by FISH. The COMT and IL-17 expressions in the right trigeminal ganglion tissue of each group were detected by western blot. RESULTS: The 60 g force and 14-day duration required the lowest stimulus intensity, the duration of grooming behavior was the longest, and the effect on COMT and IL-17 was the most significant. In the model group, formation of digestive cavity was seen in the trigeminal ganglion tissue, with infiltration of inflammatory cells, upregulation of the COMT and IL-17 expressions, and significant increase in the tooth movement distance. Compared with the model group, the shCOMT experimental group and the COMT antagonist group significantly improved the trigeminal ganglion tissue injury, significantly decreased the tooth movement distance, and significantly inhibited the COMT and IL-17 expressions. CONCLUSION: The efficiency of tooth movement can be influenced by interfering the COMT-related gene expression. This proves that the COMT system can regulate the orthodontic tooth movement pain.

COMT-Catalyzed Palmitic Acid Methyl Ester Biosynthesis in Perivascular Adipose Tissue and its Potential Role Against Hypertension.

Decreased release of palmitic acid methyl ester (PAME), a vasodilator, from perivascular adipose tissue (PVAT) might contribute to hypertension pathogenesis. However, the PAME biosynthetic pathway remains unclear. In this study, we hypothesized that PAME is biosynthesized from palmitic acid (PA) via human catechol-O-methyltransferase (COMT) catalysis and that decreased PAME biosynthesis plays a role in hypertension pathogenesis. We compared PAME biosynthesis between age-matched normotensive Wistar Kyoto (WKY) rats and hypertensive spontaneously hypertensive rats (SHRs) and investigated the effects of losartan treatment on PAME biosynthesis. Computational molecular modeling indicated that PA binds well at the active site of COMT. Furthermore, in in vitro enzymatic assays in the presence of COMT and S-5'-adenosyl-L-methionine (AdoMet), the stable isotope [13C16]-PA was methylated to form [13C16]-PAME in incubation medium or the Krebs-Henseleit solution containing 3T3-L1 adipocytes or rat PVAT. The adipocytes and PVATs expressed membrane-bound (MB)-COMT and soluble (S)-COMT proteins. [13C16]-PA methylation to form [13C16]-PAME in 3T3-L1 adipocytes and rat PVAT was blocked by various COMT inhibitors, such as S-(5'-adenosyl)-L-homocysteine, adenosine-2',3'-dialdehyde, and tolcapone. MB- and S-COMT levels in PVATs of established SHRs were significantly lower than those in PVATs of age-matched normotensive WKY rats, with decreased [13C16]-PA methylation to form [13C16]-PAME. This decrease was reversed by losartan, an angiotensin II (Ang II) type 1 receptor antagonist. Therefore, PAME biosynthesis in rat PVAT is dependent on AdoMet, catalyzed by COMT, and decreased in SHRs, further supporting the role of PVAT/PAME in hypertension pathogenesis. Moreover, the antihypertensive effect of losartan might be due partly to its increased PAME biosynthesis. SIGNIFICANCE STATEMENT: PAME is a key PVAT-derived relaxing factor. We for the first time demonstrate that PAME is synthesized through PA methylation via the S-5'-adenosyl-L-methionine-dependent COMT catalyzation pathway. Moreover, we confirmed PVAT dysfunction in the hypertensive state. COMT-dependent PAME biosynthesis is involved in Ang II receptor type 1-mediated blood pressure regulation, as evidenced by the reversal of decreased PAME biosynthesis in PVAT by losartan in hypertensive rats. This finding might help in developing novel therapeutic or preventive strategies against hypertension.

Effect of COMT Val108/158Met genotype on risk for polydipsia in chronic patients with schizophrenia.

Polydipsia is a serious condition often seen among patients with schizophrenia (SCZ). The cause of polydipsia is unknown; hence, it is hard to treat or manage. Animal studies showed that the drinking behavior is regulated by central dopaminergic neurotransmission at the hypothalamus. Meanwhile, the existence of a genetic predisposition to polydipsia in patients with SCZ has been suggested. The purpose of this study was to assess whether a functional polymorphism, Val(108/158)Met in the gene for catechol-O-methyltransferase (COMT), is associated with susceptibility to polydipsia using a Japanese sample of SCZ. Our sample includes 330 chronic patients with SCZ (83 polydipsic patients and 247 non-polydipsic controls). The common COMT Val(108/158)Met polymorphism was genotyped, and the differences in genotype distribution and allele frequency between cases and controls were evaluated using the χ(2) test. A significant association between the COMT Val(108/158)Met polymorphism and polydipsia was found (genotype distribution: χ(2) = 13.0, df = 2, p = 0.001; allele frequency: χ(2) = 7.50, df = 1, p = 0.006). The high-COMT activity group (Val/Val) was more frequent among patients with polydipsia compared with the low-COMT activity group (Val/Met + Met/Met) [odds ratio (OR) = 2.46]. The association survived after controlling for other possible confounding factors, including gender, age, age of onset, current antipsychotic dose, and smoking status. Our results suggest that the COMT Val(108/158)Met genotype may confer susceptibility to polydipsia in SCZ. To our knowledge, this is the first association study between the COMT gene and polydipsia in SCZ. Further studies with larger sample sizes are warranted to confirm present findings.

Influence of catechol-O-methyltransferase Val158Met polymorphism on startle response in the presence of high estradiol levels.

INTRODUCTION: both human and animal studies have shown a somewhat complex COMT-by-sex interaction effect on brain function and dysfunction. A functional variation in the gene coding for the catechol-O-methyltransferase (COMT) enzyme, which metabolizes dopamine and noradrenaline, has been related to executive and emotional functions, and to sex dimorphism. AIM: to investigate if COMT Val158Met genotype influences startle response in pregnant women, given their physiologically elevated estradiol levels. METHODS: seventy-three pregnant women were assessed in gestational week 38 for acoustic startle response, measured by electromyography of the blink reflex, during control condition, positive and negative anticipation stimuli, and pleasant and unpleasant image stimuli. A blood sample was taken for measurement of estradiol levels and genetic analysis. RESULTS: the results indicated a COMT Val158Met effect on startle response across all conditions (main effect of genotype, F(2,70=3.58), p=0.033), where Val/Val women displayed higher startle magnitudes than Val/Met carriers (Cohen's d=0.71). No significant difference by genotype was found in affective modulation. The findings also suggested an estrogen dose-dependent effect of COMT Val158Met on startle reflex. Among women with higher pregnancy-induced estradiol levels, Val/Val carriers had markedly higher startle response across conditions than heterozygotes (Cohen's d=1.36; F(4,21=11.07); p=0.003), while this effect was not present in women with estradiol levels under the median concentration. CONCLUSIONS: the observed effect of COMT Val158Met by estradiol on overall startle response is likely to be due to a variable noradrenergic transmission depending on COMT activity in a possible interaction with estradiol.

Impact of COMT Val 108/158 Met and DRD2 Taq1B gene polymorphisms on vulnerability to cigarette smoking of Thai males.

The nicotine in cigarette smoke can stimulate the dopaminergic reward pathways. The catechol O-methyltransferase gene (COMT) and dopamine receptor 2 gene (DRD2) are dopamine-related genes. Genetic polymorphisms in these two genes are potential candidates in determining an individual's predisposition to cigarette smoking. The purposes of this study were to examine the association between two polymorphisms in COMT Val (108/158) Met and DRD2 Taq1B and anthropometric-biochemical parameters and to ascertain the association between these polymorphisms and cigarette smoking. The levels of anthropometric-biochemical parameters were determined. COMT Val (108/158) Met and DRD2 Taq1B polymorphisms were genotyped by polymerase chain reaction-restriction fragment length polymorphism technique. With regard to COMT Val (108/158) Met and DRD2 Taq1B polymorphisms, no differences were found in anthropometric-biochemical variables, except for thiocyanate concentration. Smoking status was significantly associated with COMT Val (108/158) Met polymorphism, but not associated with DRD2 Taq1B polymorphism. Logistic regression analysis showed that COMT Val (108/158) Met gene polymorphism, educational status, parental smoking, and alcohol consumption had statistically significant impacts on cigarette smoking. The results suggest that COMT Val (108/158) Met genetic polymorphisms, but not DRD2 Taq1B, may influence susceptibility to cigarette smoking among Thai males.

Monoamine oxidase A down-regulation contributes to high metanephrine concentration in pheochromocytoma.

CONTEXT: The high diagnostic performance of plasma-free metanephrines (metanephrine and normetanephrine) (MN) for pheochromocytoma (PHEO) results from the tumoral expression of catechol-O-methyltransferase (COMT), the enzyme involved in O-methylation of catecholamines (CAT). Intriguingly, metanephrine, in contrast to epinephrine, is not remarkably secreted during a stress in hypertensive or normotensive subjects, whereas in PHEO patients CAT and MN are both raised to high levels. Because epinephrine and metanephrine are almost exclusively produced by the adrenal medulla, this suggests distinct CAT metabolism in chromaffin cells and pheochromocytes. OBJECTIVE: The objective of the study was to compare CAT metabolism between adrenal medulla and PHEO tissue regarding related enzyme expression including monoamine oxidases (MAO) and COMT. DESIGN: A multicenter comparative study was conducted. STUDY PARTICIPANTS: The study included 21 patients with a histologically confirmed PHEO and eight adrenal glands as control. MAIN OUTCOME MEASURES: CAT, dihydroxyphenol-glycol, 3,4-dihydroxyphenylacetic acid, and MN were measured in adrenal medulla and PHEO tissue. Western blot, quantitative RT-PCR and immunofluorescence studies for MAOA, MAOB, tyrosine hydroxylase, dopamine ß-hydroxylase, L-amino acid decarboxylase, and COMT were applied on tissue homogenates and cell preparations. RESULTS: At both the protein and mRNA levels, MAOA and COMT are detected less often in PHEO compared with adrenal medulla, conversely to tyrosine hydroxylase, L-amino acid decarboxylase, and dopamine ß-hydroxylase, much more expressed in tumor tissue. MAOB protein is detected less often in tumor but not differently expressed at the mRNA level. Dihydroxyphenol-glycol is virtually absent from tumor, whereas MN, produced by COMT, rises to 4.6-fold compared with adrenal medulla tissue. MAOA down-regulation was observed in 100% of tumors studied, irrespectively of genetic alteration identified; on the other hand, MAOA was strongly expressed in all adrenal medulla collected independently of age, gender, or late sympathetic activation of the deceased donor. CONCLUSION: High concentrations of MN in tumor do not only arise from CAT overproduction but also from low MAOA expression, resulting in higher substrate availability for COMT.

Psychological distress in fibromyalgia patients: a role for catechol-O-methyl-transferase Val158met polymorphism.

OBJECTIVE: Fibromyalgia (FM) has been related to biochemical alterations, central pain sensitization and psychological distress. Among genetic and environmental hypotheses, a role was suggested for catechol-O-methyl-transferase (COMT), a modulator in the metabolism of monoaminergic neurotransmitters. METHOD: This study compared the COMT Val158Met enzyme polymorphism (rs4680) of 198 FM patients to 99 pain-free controls. Psychological and functional aspects were assessed through investigating anxiety, depression, catastrophizing, perceived health, and functional status. RESULTS: The distribution of the COMT Val158Met polymorphism was similar in FM and controls. Out of 198 patients, 137 were able to stop medication before evaluation. In these patients, the COMT Val158Met genotype was associated with specific psychological profiles. The Met/Met subgroup scored systematically worse on all psychological and functional variables. All variables displayed a "genotype-trend effect" with the Met/Met and Val/Val subgroups at the two ends of the scores. Genotypes distribution in the 61 patients unable to stop medication was significantly different from that of patients able to stop medication and controls (p = .002 and p = .018, respectively) with an increase in the proportion of the Met/Met genotype associated to the lowest COMT activity. These results suggest a possible role of COMT Val158Met polymorphism in the psychological distress observed in FM. CONCLUSIONS: The association of COMT genotype with psychological distress may be of importance as identifying subgroups is a challenge in the diagnosis and treatment of fibromyalgia patients. This association may contribute to open new perspectives into the understanding of the pathophysiology of fibromyalgia and stress-related genes.

Catechol-O-methyltransferase is dispensable for vascular protection by estradiol in mouse models of atherosclerosis and neointima formation.

Estradiol is converted to the biologically active metabolite 2-methoxyestradiol via the activity of the enzyme catechol-O-methyltransferase (COMT). Exogenous administration of both estradiol and 2-methoxyestradiol reduces experimental atherosclerosis and neointima formation, and COMT-dependent formation of 2-methoxyestradiol likely mediates the antimitogenic effect of estradiol on smooth muscle cells in vitro. This study evaluated whether 2-methoxyestradiol mediates the vasculoprotective actions of estradiol in vivo. Wild-type (WT) and COMT knockout (COMTKO) mice on an apolipoprotein E-deficient background were gonadectomized and treated with estradiol or placebo. Exogenous estradiol reduced atherosclerotic lesion formation in both females (WT, -78%; COMTKO, -82%) and males (WT, -48%; COMTKO, -53%) and was equally effective in both genotypes. We further evaluated how exogenous estradiol affected neointima formation after ligation of the carotid artery in ovariectomized female mice; estradiol reduced intimal hyperplasia to a similar extent in both WT (-80%) and COMTKO (-77%) mice. In ovarian-intact female COMTKO mice, atherosclerosis was decreased (-25%) compared with WT controls. In conclusion, the COMT enzyme is dispensable for vascular protection by exogenous estradiol in experimental atherosclerosis and neointima formation in vivo. Instead, COMT deficiency in virgin female mice with intact endogenous production of estradiol results in relative protection against atherosclerosis.

COMT moderates the relation of daily maladaptive coping and pain in fibromyalgia.

Forty-five women with fibromyalgia (FM) engaged in a 30-day electronic diary assessment, recording daily ratings of pain and 2 forms of maladaptive coping: pain catastrophizing and pain attention. Participants were genotyped for the val(158)met single nucleotide polymorphism (rs4680) in the catechol-O-methyltransferase (COMT) gene. COMT genotype moderated the daily relations of both maladaptive coping processes and pain. FM women with the homozygous met/met genotype evidenced more pain on days when pain catastrophizing was elevated relative to heterozygous and homozygous val(158) carriers. FM women with the homozygous met/met genotype evidenced more pain on days when pain attention was elevated relative to those with the homozygous val/val genotype. Evidence is presented to suggest that these are independent effects. The findings provide multimeasure and multimethod support for genetic moderation of a maladaptive coping and pain process, which has been previously characterized in a sample of postoperative shoulder pain patients. Further, the findings advance our understanding of the role of COMT in FM, suggesting that genetic variation in the val(158)met polymorphism may affect FM pain through pathways of pain-related cognition. This study examined 2 forms of maladaptive coping: pain catastrophizing and pain attention. The findings provide multimeasure and multimethod support for genetic moderation of a maladaptive coping and pain process and suggest that genetic variation in the val(158)met polymorphism may affect fibromyalgia pain through pathways of pain-related cognition.

Impact of CYP1A1 and COMT genotypes on breast cancer risk in Mexican women: a pilot study.

BACKGROUND: Data suggest that estrogen-metabolizing genes may be involved in breast cancer carcinogenesis. OBJECTIVE: The aim of this study was to determine the association of CYP1A1 and COMT polymorphisms with this disease. MATERIAL AND METHODS: A pilot case-control study was conducted with Mexican women. Ninety-one breast cancer patients and 94 healthy controls were selected. Epidemiological and clinical questionnaires were answered by all participants, and genotyping data were obtained. CYP1A1 3801 T>C (rs4646903), CYP1A1 4889 A>G (rs1048943) and COMT 1947 G>A (rs4680) polymorphisms were analyzed by PCR-RFLP. RESULTS: The results showed a high risk of breast cancer in women carrying the CYP1A1 (3801 T>C) m2/m2 genotype (OR=2.52; 95%CI=1.04-6.08). The risk was higher in postmenopausal women (OR=3.38; 95%CI=1.05-10.87). No association between COMT 1947 G>A (rs4680) or CYP1A1 4889 A>G (rs1048943) and breast cancer was found. CONCLUSIONS: This study suggests that the CYP1A1 (3801 T>C) m2/m2 genotype may contribute to breast cancer susceptibility in Mexican women.

Inhibition of catechol-Omicron-methyltransferase activity in human breast cancer cells enhances the biological effect of the green tea polyphenol (-)-EGCG.

Tea is one of the most popular beverages in the world and has been studied extensively as a health-promoting beverage that may act to prevent a number of chronic diseases and cancers. (-)-Epigallocatechin gallate [(-)-EGCG], a major component in green tea, is unstable under physiological conditions and methylation of (-)-EGCG by catechol-Omicron-methyltransferase (COMT) is a modification that reduces the biological activity of (-)-EGCG. In the current study, we hypothesized that suppression of COMT activity in human breast cancer cells could increase the proteasome-inhibitory potency of (-)-EGCG and therefore enhance its tumor cell growth-inhibitory activity. We first determined the COMT genotype and basal levels of COMT activity in various human breast cancer cell lines. Furthermore, when breast cancer MDA-MB-231 cells containing high COMT activity were tested, the diminished COMT activity apparently increased the effectiveness of (-)-EGCG via augmented proteasome inhibition and apoptosis induction. This study supplements the previous findings that methylated (-)-EGCG is less bioactive and supports the notion that COMT inhibition may increase the anti-cancer properties of tea polyphenols and the combination may serve as a novel approach or supplemental treatment for breast cancer chemotherapy.

Cognitive effects of nicotine: genetic moderators.

Cigarette smoking is the main preventable cause of death in developed countries, and the development of more effective treatments is necessary. Cumulating evidence suggests that cognitive enhancement may contribute to the addictive actions of nicotine. Several studies have demonstrated that nicotine enhances cognitive performance in both smokers and non-smokers. Genetic studies support the role of both dopamine (DA) and nicotinic acetylcholine receptors (nAChRs) associated with nicotine-induced cognitive enhancement. Based on knockout mice studies, beta2 nAChRs are thought to be essential in mediating the cognitive effects of nicotine. alpha7nAChRs are associated with attentional and sensory filtering response, especially in schizophrenic individuals. Genetic variation in D2 type DA receptors and the catechol-O-methyltransferase enzyme appears to moderate cognitive deficits induced by smoking abstinence. Serotonin transporter (5-HTT) gene variation also moderates nicotine-induced improvement in spatial working memory. Less is known about the contribution of genetic variation in DA transporter and D4 type DA receptor genetic variation on the cognitive effects of nicotine. Future research will provide a clearer understanding of the mechanism underlying the cognitive-enhancing actions of nicotine.

Why do young women smoke? VII COMT as a risk modifying gene for Nicotine dependence - role of gene-gene interaction, personality, and environmental factors.

OBJECTIVES: Catechol-O-methyltransferase (COMT) may be a risk modifying gene for Nicotine dependence (ND) rather than a direct susceptibility gene for this phenotype. Brain nicotinic cholinergic receptors modulate dopaminergic transmission, and several variants within the neighboring CHRNA5-CHRNA3 genes have been associated with ND. Therefore, it is biologically reasonable to study the interactive contribution of COMT and the CHRNA5 and CHRNA3 genes to ND. METHODS: Using a case-control sample of 90 young, Israeli, Jewish female smokers (FTND ≥ 4) and 108 controls (FTND = 0 during heaviest period of smoking), we studied association with ND of 8 COMT tagging SNPs, their interaction with tagging CHRNA5-A3 SNPs and the role of background, personality, and environmental factors. RESULTS: None of the COMT SNPs were associated directly with ND. In pairwise interaction analysis of SNPs from the two loci (COMT SNP-CHRNA5-CHRNA3 SNP), the interaction of intronic COMT SNP, rs9332377, with CHRNA3 3'UTR SNP rs660652 was significantly associated with ND (p = 0.0005), withstanding correction for multiple testing. CONCLUSION: Addition of the genetic interaction variable into a model of non-genetic ND predictors [parental smoking, novelty seeking (NS), and lifetime history of trauma], substantially increases the percentage of ND variance explained by the model, as well as the percentage of cases correctly identified by it.

Catechol O-methyltransferase pharmacogenomics: human liver genotype-phenotype correlation and proximal promoter studies.

OBJECTIVES: Catechol O-methyltransferase (COMT) is expressed as both soluble (S) and membrane-bound (MB) isoforms, with S-COMT predominantly expressed in the liver. A common nonsynonymous single nucleotide polymorphism (SNP), 472G > A (108/158Val > Met, S/MB), has been associated with variation in levels of COMT enzyme activity and thermal stability. We set out to test the hypothesis that additional COMT polymorphisms might also be associated with phenotypic variation. METHODS: We phenotyped 268 liver biopsy samples for S-COMT activity and thermal stability, resequenced a portion of the gene that had not been resequenced earlier, and genotyped DNA from these same samples for 16 COMT polymorphisms. RESULTS: There was a significant association between the two COMT phenotypes and genotype at the codon 108 SNP. A haplotype-based approach was then used to assess the possible association of other polymorphisms with phenotype. Specifically, the codon 108 SNP explained 20.4% of variance in enzyme activity (P < 10), and 59% of variance in thermal stability (P < 10). Haplotypes that included SNPs at cDNA nucleotides 408 and 472 explained additional variance in enzyme activity (up to 24.4%), and the addition to the haplotype of a SNP at intron 2 (51) explained a total of 27.5% of the variance. However, no SNPs beyond that at the nucleotide 472G > A polymorphism were associated with variation in thermal stability. We also observed a three-fold variation in the ability of reporter gene constructs for 'proximal promoter' haplotypes to drive transcription. CONCLUSION: The common COMT 108Val > Met polymorphism is associated with human liver S-COMT activity and thermal stability, but additional COMT SNPs also contribute to variation in activity.

Variants in COMT and spontaneous smoking cessation: retrospective cohort analysis of 925 cessation events.

Genome-wide studies have identified single nucleotide polymorphisms associated with smoking behaviour and nicotine dependence. Less is known about genetic determinants of smoking cessation, but rs4680 in COMT has recently been shown to explain a substantial proportion of the variation in cessation in the general population. We attempted to replicate the reported, clinically relevant effect in a population-based retrospective cohort analysis of 1443 ever-heavy smokers, of whom 925 had reached abstinence. In Cox regression models, neither rs4680 nor two polymorphisms nearby were associated with smoking cessation. The adjusted relative cessation rate (95% confidence interval) in rs4680 methionine carriers in reference to valine homozygotes was 0.97 (0.83-1.12). The absence of a significant effect of rs4680 in this statistically well-powered study - the 95% confidence interval even excluding the previously reported effect - highlights the need for rigorous replication efforts and suggests that rs4680 genotype should not yet be considered informative for smoking patient care.

Antipsychotic-induced tardive dyskinesia and polymorphic variations in COMT, DRD2, CYP1A2 and MnSOD genes: a meta-analysis of pharmacogenetic interactions.

Despite accumulating evidence pointing to a genetic basis for tardive dyskinesia, results to date have been inconsistent owing to limited statistical power and limitations in molecular genetic methodology. A Medline, EMBASE and PsychINFO search for literature published between 1976 and June 2007 was performed, yielding 20 studies from which data were extracted for calculation of pooled estimates using meta-analytic techniques. Evidence from pooled data for genetic association with tardive dyskinesia (TD) showed (1) in COMT(val158met), using Val-Val homozygotes as reference category, a protective effect for Val-Met heterozygotes (OR=0.63, 95% CI: 0.46-0.86, P=0.004) and Met carriers (OR=0.66, 95% CI: 0.49-0.88, P=0.005); (2) in Taq1A in DRD2, using the A1 variant as reference category, a risk-increasing effect for the A2 variant (OR=1.30, 95% CI: 1.03-1.65, P=0.026), and A2-A2 homozygotes using A1-A1 as reference category (OR=1.80, 95% CI: 1.03-3.15, P=0.037); (3) in MnSOD Ala-9Val, using Ala-Ala homozygotes as reference category, a protective effect for Ala-Val (OR=0.37, 95% CI: 0.17-0.79, P=0.009) and for Val carriers (OR=0.49, 95% CI: 0.24-1.00, P=0.047). These analyses suggest multiple genetic influences on TD, indicative of pharmacogenetic interactions. Although associations are small, the effects underlying them may be subject to interactions with other loci that, when identified, may have acceptable predictive power. Future genetic research will take advantage of new genomic knowledge. Molecular Psychiatry (2008) 13, 544-556; doi:10.1038/sj.mp.4002142; published online 8 January 2008.

Catechol-o-methyltransferase and methoxyestradiols participate in the intraoviductal nongenomic pathway through which estradiol accelerates egg transport in cycling rats.

Estradiol (E(2)) accelerates oviductal egg transport through intraoviductal nongenomic pathways in cyclic rats and through genomic pathways in pregnant rats. This shift in pathways, which we have provisionally designated as intracellular path shifting (IPS), is caused by mating-associated signals and represents a novel and hitherto unrecognized phenomenon. The mechanism underlying IPS is currently under investigation. Using microarray analysis, we identified several genes the expression levels of which changed in the rat oviduct within 6 hours of mating. Among these genes, the mRNA level for the enzyme catechol-O-methyltransferase (COMT), which produces methoxyestradiols from hydroxyestradiols, decreased 6-fold, as confirmed by real-time PCR. O-methylation of 2-hydroxyestradiol was up to 4-fold higher in oviductal protein extracts from cyclic rats than from pregnant rats and was blocked by OR486, which is a selective inhibitor of COMT. The levels in the rat oviduct of mRNA and protein for cytochrome P450 isoforms 1A1 and 1B1, which form hydroxyestradiols, were detected by RT-PCR and Western blotting. We explored whether methoxyestradiols participate in the pathways involved in E(2)-accelerated egg transport. Intrabursal application of OR486 prevented E(2) from accelerating egg transport in cyclic rats but not in pregnant rats, whereas 2-methoxyestradiol (2ME) and 4-methoxyestradiol mimicked the effect of E(2) on egg transport in cyclic rats but not in pregnant rats. The effect of 2ME on egg transport was blocked by intrabursal administration of the protein kinase inhibitor H-89 or the antiestrogen ICI 182780, but not by actinomycin D or OR486. We conclude that in the absence of mating, COMT-mediated formation of methoxyestradiols in the oviduct is essential for the nongenomic pathway through which E(2) accelerates egg transport in the rat oviduct. Yet unidentified mating-associated signals, which act directly on oviductal cells, shut down the E(2) nongenomic signaling pathway upstream and downstream of methoxyestradiols. These findings highlight a physiological role for methoxyestradiols in the female genital tract, thereby confirming the occurrence of and providing a partial explanation for the mechanism underlying IPS.

A general liquid chromatography/mass spectroscopy-based assay for detection and quantitation of methyltransferase activity.

Methyltransferases form a large class of enzymes, most of which use S-adenosylmethionine as the methyl donor. In fact, S-adenosylmethionine is second only to ATP in the variety of reactions for which it serves as a cofactor. Several methods to measure methyltransferase activity have been described, most of which are applicable only to specific enzymes and/or substrates. In this work we describe a sensitive liquid chromatography/mass spectroscopy-based methyltransferase assay. The assay monitors the conversion of S-adenosylmethionine to S-adenosylhomocysteine and can be applied to any methyltransferase and substrate of interest. We used the well-characterized enzyme catechol O-methyltransferase to demonstrate that the assay can monitor activity with a variety of substrates, can identify new substrates, and can be used even with crude preparation of enzyme. Furthermore, we demonstrate the utility of the assay for kinetic characterization of enzymatic activity.

Catechol-O-methyl-transferase functional polymorphism and nicotine dependence: an evaluation of nonreplicated results.

Review articles have focused attention on and cited possible reasons for the nonreplication of genetic association studies. Herein, we illustrate how one might work through these possible reasons to make a judgment about the most plausible reason(s) when faced with two or more studies which yield seemingly inconsistent results. In the first study, 342 treatment-seeking smokers were genotyped for the Val108Met polymorphism in the functional catechol-O-methyl-transferase (COMT) locus. Alleles coding Val at codon 108 are denoted as H and those coding Met are denoted as L. An association between presence of the "H" (high activity) allele and pretreatment level of nicotine dependence level using the Fagerstrom Test for Nicotine Dependence was detected (P = 0.0072), after controlling for baseline body mass index (BMI, kg/m2), depression symptoms, and age. To validate this initial finding, 443 treatment-seeking smokers from an independent smoking cessation clinical trial were genotyped for the COMT polymorphism. Within the second study, no association between presence of the "H" allele and nicotine dependence was detected (P = 0.6418) after controlling for baseline BMI, depression symptoms, and age. We critically reviewed both studies with regard to often cited reasons for nonreplication, including type I error, population stratification, low statistical power, and imprecise measures of phenotype. Although in our opinion the failure to replicate the initial association in the second study is likely either the result of low statistical power to detect a small effect or effect heterogeneity, thorough analyses failed to definitively identify the reason for nonreplication.