Impact of Dyrk1A level on alcohol metabolism

Association of NQO1 levels and its genetic polymorphism with susceptibility to methamphetamine dependence

BACKGROUND

The quinone oxidoreductase 1 (NQO1) gene was involved in the pathophysiological process of illicit drugs abuse, and its polymorphisms might be associated with methamphetamine (METH) dependence susceptibility. The purpose of this study was to examine the NQO1 mRNA and protein levels and to analyze the 609C/T polymorphism (rs1800566) between METH-dependent patients and controls.

METHODS

A total of 392 METH-dependent patients (cases) and 669 healthy controls (controls) were enrolled in the study. The quantitative real-time polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA) were used to detect the relative expressions of NQO1 mRNA in PBMCs and protein levels in plasma, respectively. PCR-restriction fragment length polymorphism (RFLP-PCR) and direct-sequencing genotyping were used to detect the alleles and genotypes of NQO1 609C/T polymorphism.

RESULTS

The levels of NQO1 mRNA in cases (3.2650 ± 2.2943) was significantly higher than in controls (1.0125 ± 0.7959) (p < 0.001), the plasma protein in cases (0.2368 ± 0.1486) was significantly lower than in controls (0.5844 ± 0.1742) (p < 0.001). The T allele of the 609C/T polymorphism significantly increased the risk of METH dependence (p = 0.032, OR = 1.214, 95%CI = 1.017-1.450). The TC and TC/TT genotypes of 609C/T were observed significantly more frequently in cases than in controls, respectively (TC vs CC: p = 0.012, OR = 1.457, 95% CI = 1.087-1.952; TC/TT vs CC: p = 0.008, OR = 1.460, 95% CI = 1.102-1.935). Similar results were obtained after adjusting for age and sex. We failed to find that any genotype of 609C/T polymorphism affected the mRNA or plasma protein levels in controls, respectively (p > 0.05).

CONCLUSION

The findings suggested that NQO1 might play an important role in the pathophysiological process of METH dependence, and the 609C/T polymorphism might contribute to the susceptibility to METH dependence in a Chinese Han population.

Ethanol-Induced Changes in Brain of Transgenic Mice Overexpressing DYRK1A

Alcoholism is a chronic relapsing disorder defined by loss of control over excessive consumption of ethanol despite damaging effects on the liver and brain. We previously showed that the overexpression in mice of Dyrk1A (TgDyrk1A, for dual-specificity tyrosine (Y) phosphorylation-regulated kinase 1A) reduces the severity of alcohol mediated liver injury. Ethanol consumption has also been associated with increased brain glutamate concentration that led to therapies targeting glutamatergic receptors and normalization of glutamatergic neurotransmission. Interestingly, mice overexpressing Dyrk1A (TgDyrk1A mice) present a reduction of glutamatergic brain transmission, which we propose could be protective against alcohol intake. To answer this question, we investigated the ethanol preference in TgDyrk1A mice using a two-bottle choice paradigm. TgDyrk1A mice showed a non-significant decrease of voluntary ethanol intake and ethanol preference compared with wild-type mice. At the peripheral level, mice overexpressing Dyrk1A show lower ethanol plasma levels, indicating a faster ethanol metabolism. At the end of the protocol, lasting 21 days, brains were extracted for protein analysis. Ethanol reduced levels of the synaptic protein PSD-95 and increased the glutamate decarboxylase GAD65, specifically in the cortex of TgDyrk1A mice. Our results suggest that overexpression of DYRK1A may cause different ethanol-induced changes in the brain.

Molecular Rescue of Dyrk1A Overexpression Alterations in Mice with Fontup® Dietary Supplement: Role of Green Tea Catechins

Epigallocatechin gallate (EGCG) is an inhibitor of DYRK1A, a serine/threonine kinase considered to be a major contributor of cognitive dysfunctions in Down syndrome (DS). Two clinical trials in adult patients with DS have shown the safety and efficacy to improve cognitive phenotypes using commercial green tea extract containing EGCG (45% content). In the present study, we performed a preclinical study using FontUp®, a new nutritional supplement with a chocolate taste specifically formulated for the nutritional needs of patients with DS and enriched with a standardized amount of EGCG in young mice overexpressing Dyrk1A (TgBACDyrk1A). This preparation is differential with previous one used, because its green tea extract has been purified to up 94% EGCG of total catechins. We analyzed the in vitro effect of green tea catechins not only for EGCG, but for others residually contained in FontUp®, on DYRK1A kinase activity. Like EGCG, epicatechin gallate was a noncompetitive inhibitor against ATP, molecular docking computations confirming these results. Oral FontUp® normalized brain and plasma biomarkers deregulated in TgBACDyrk1A, without negative effect on liver and cardiac functions. We compared the bioavailability of EGCG in plasma and brain of mice and have demonstrated that EGCG had well crossed the blood-brain barrier.

Deciphering the Link Between Hyperhomocysteinemia and Ceramide Metabolism in Alzheimer-Type Neurodegeneration

Aging is one of the strongest risk factor for Alzheimer's disease (AD). However, several data suggest that dyslipidemia can either contribute or serve as co-factors in AD appearance. AD could be examined as a metabolic disorder mediated by peripheral insulin resistance. Insulin resistance is associated with dyslipidemia, which results in increased hepatic ceramide generation. Hepatic steatosis induces pro-inflammatory cytokine activation which is mediated by the increased ceramides production. Ceramides levels increased in cells due to perturbation in sphingolipid metabolism and upregulated expression of enzymes involved in ceramide synthesis. Cytotoxic ceramides and related molecules generated in liver promote insulin resistance, traffic through the circulation due to injury or cell death caused by local liver inflammation, and because of their hydrophobic nature, they can cross the blood-brain barrier and thereby exert neurotoxic responses as reducing insulin signaling and increasing pro-inflammatory cytokines. These abnormalities propagate a cascade of neurodegeneration associated with oxidative stress and ceramide generation, which potentiate brain insulin resistance, apoptosis, myelin degeneration, and neuro-inflammation. Therefore, excess of toxic lipids generated in liver can cause neurodegeneration. Elevated homocysteine level is also a risk factor for AD pathology and is narrowly associated with metabolic diseases and non-alcoholic fatty liver disease. The existence of a homocysteine/ceramides signaling pathway suggests that homocysteine toxicity could be partly mediated by intracellular ceramide accumulation due to stimulation of ceramide synthase. In this article, we briefly examined the role of homocysteine and ceramide metabolism linking metabolic diseases and non-alcoholic fatty liver disease to AD. We therefore analyzed the expression of mainly enzymes implicated in ceramide and sphingolipid metabolism and demonstrated deregulation of de novo ceramide biosynthesis and S1P metabolism in liver and brain of hyperhomocysteinemic mice.