Alcohol addiction: a molecular biology perspective.

Alcohol misuse represents worldwide an important risk factor for death and disability. Excessive alcohol consumption is widely diffused in different ethnicities and alcohol use is part of the lifestyle of both young and old people. The genetic basis of alcohol dependence concerning ethanol metabolism and the pathways of reward circuits are well known. The role of genetic variants in the neurobiology of addiction as well as in response to medication in alcoholism therapy still represents an intriguing argument that needs to be deeply analyzed and explained. The molecular approach to the study of these aspects could be difficult because of the large number of genes and variations involved. Our work is intended to offer an overview of genes and variants involved in alcohol addiction and pharmacogenetics. Our aim is to delineate a molecular approach strategy to look at alcohol dependence from a genetic and applicative point of view. The indications provided in this work should be of help for those who wish to undertake a molecular study of this multifactorial disease

Dopamine transporter and transmission of psychopathological risk. A review of gene-environment interplay

Research underlines that intergenerational transmission of psychopathological risk results from a complex interplay of genetic and environmental risk factors which predispose child to develop emotionalbehavioral problems. Mechanisms of transmission are poorly understood, but few studies have focused on the role played by dopamine transporter (DAT) gene. This review aims to examine mediating mechanism of DAT genotype-environmental interaction (GxE), DAT genotype-environmental correlation (rGE), and methylation status involved in transmission of psychopathological risk. The review of literature was made through researches in university libraries on paper material, and telematics systems research. Studies have evidenced that DAT is implicated in intergenerational transmission of psychopathological risk. Results are mixed regarding its genetic variants, but mechanisms through which this gene can affect both quality of parenting and child development are partially established. Only few studies have examined methylation mechanisms that can be implicated. Findings suggest to involve an improved focus on DAT genotypes, methylation status associated, and their relationship with environment to better understanding child’s vulnerability and resilience following exposure to contextual risk factors associated with parental psychopathological symptoms

Associations among internet addiction, genetic polymorphisms, family functioning, and psychopathological risk. Cross-sectional exploratory study

Background: International research has emphasized that youths are at higher risk for the onset of internet addiction (IA), but studies investigating biological, psychological, and social factors associated with this condition are limited. Objective: This study aims to investigate the possible association between IA and genetic polymorphisms in monoamine oxidase A (MAO-A), serotonin-transporter (5-HTTPR), dopamine receptor (DRD4), and dopamine transporter (DAT1) genes by considering the role played by the perception of young adults in their family functioning and their depression, anxiety, and avoidant personality problems. Methods: In a sample of 104 male and female young adults aged between 19 and 23 years (mean age 21.87, SD 2.29 years) recruited from universities in the central southern part of Italy, we addressed the presence of IA using the Young criteria of the IA test. Moreover, the perception of young adults of their family functioning and their psychopathological symptoms were assessed through the Family Assessment Device (FAD) and the Adult Self-Report, respectively. Results: We found no significant association between IA and any genetic polymorphisms, neither among males or females. Young adults with IA reported significantly higher scores in the subscale of FAD affective responsiveness (AR; P=.01) and in depressive problems (P=.02), anxiety problems (P=.009), and avoidant personality problems (P=.003) than those in the control group. Results of mediation analyses showed a mediation role played by depressive symptoms (B=0.99; 95% CI 0.22 to 1.97) and avoidant personality problems (B=1.09; 95% CI 0.32 to 2.05) of young adults on the relationship between the FAD, AR, and IA. Finally, this relationship was moderated by the genotype of the 5-HTTLPR (P<.001), DAT1 (P<.001), and MAO-A (P<.001) genes in young adults. Conclusions: This exploratory study supports the recent evidence on the mutual relationship among biological, individual, and social risk factors associated with IA in young adulthood. Our findings may have important clinical implications for the development of prevention and treatment programs

Long telomeric C-rich 5'-tails in human replicating cells.

Telomeres protect the ends of linear chromosomes from abnormal recombination events and buffer them against terminal DNA loss. Models of telomere replication predict that two daughter molecules have one end that is blunt, the product of leading-strand synthesis, and one end with a short G-rich 3′-overhang. However, experimental data from proliferating cells are not completely consistent with this model. For example, telomeres of human chromosomes have long G-rich 3′-overhangs, and the persistence of blunt ends is uncertain. Here we show that the product of leading-strand synthesis is not always blunt but can contain a long C-rich 5′-tail, the incompletely replicated template of the leading strand. We examined the presence of G-rich and C-rich single-strand DNA in fibroblasts and HeLa cells. Although there were no significant changes in the length distribution of the 3′-overhang, the 5′-overhangs were mostly present in S phase. Similar results were obtained using telomerase-negative fibroblasts. The amount and the length distribution of the 5′ C-rich tails strongly correlate with the proliferative rate of the cell cultures. Our results suggest that, contrary to what has commonly been supposed, completion of leading-strand synthesis is inefficient and could well drive telomere shortening

Cross-correlations between motifs in the 5′-UTR of DAT1 gene. Findings from Parkinson’s disease

Parkinson’s disease (PD) is a neuro-degenerative disorder affecting the striatal motor system, caused by the loss of neuronal cells in the mid-brain, where reduced amounts of dopamine do cause involuntary movements and others symptoms. Alterations of methylome have been reported in PD epigenomic studies, and also human dopamine transporter gene (DAT1, SLC6A3) is considered as a candidate risk factor for PD. Since the DNA methylation on DAT promoter may well have a role in the development of this disease, we aimed to further assess the epigenetic control, by focusing on specific CpG sites located in the 5′ -untranslated region (5′ -UTR) of the DAT1 gene. Significant changes in DAT 5′ -UTR methylation were already found in peripheral blood mononuclear cells (PBMCs) of PD subjects (Rubino et al., 2020). Of note, methylation values at the CpG 5 were increased. We run on same data a novel statistical approach: crosscorrelation between pairs of loci. CpG 5 was the only always-differing variable but, alternatively, CpGs 2 and 6 or CpGs 1 and 3 were also significantly correlated with CpG 5. Interestingly, this picture emerged for those patients whose M2xM6 index was above-median; loci were rather independent for below-median patients. Present data may shed light into dynamics occurring at 5′ -UTR of DAT1, a gene involved in PD but also in many psycho-physiological pathologies

DNA methylation at the DAT promoter and risk for psychopathology. Intergenerational transmission between school-age youths and their parents in a community sample

Background: The effect of gene polymorphisms and promoter methylation, associated with maladaptive developmental outcomes, vary depending on environmental factors (e.g., parental psychopathology). Most studies have focused on 0- to 5-year-old children, adolescents, or adults, whereas there is dearth of research on school-age youths and pre-adolescents. Methods: In a sample of 21 families recruited at schools, we addressed parents' psychopathological symptoms (through SCL-90-R); offspring emotional-behavioral functioning (through CBCL-6-18); dopamine transporter gene (DAT1) for epigenetic status of the 5'-untranslated region (UTR) and for genotype, i.e., variable number of tandem repeats polymorphism at the 3'-UTR. Possible associations were explored between bio-genetic and psychological characteristics within the same individual and between triplets of children, mothers, and fathers. Results: DAT methylation of CpG at positions M1, M6, and M7 in mothers was correlated with maternal (phobic) anxiety, whereas in fathers' position M6 was related to paternal depression, anxiety, hostility, psychoticism, and higher Global Severity Index (GSI). No significant correlations were found between maternal and offspring DAT methylation. Significant correlations were found between fathers' methylation at CpG M1 and children's methylation at CpG M6. Linear regressions showed that mothers and fathers' GSI predicted children's methylation at CpG sites M2, M3, and M6, whereas fathers' GSI predicted children's methylation at CpG sites, particularly M1, M2, and M6. Moreover, offspring methylation of DAT at CpG M2 predicted somatic complaint, internalizing and attention problems; methylation of DAT at CpG M6 predicted withdraw. Conclusion: This study may have important clinical implication for the prevention and treatment of emotional-behavioral difficulties in children, as it adds to previous knowledge about the role of genetic and environmental factors in predicting psychopathological symptoms within non-clinical population

Genetic architecture of MAPT gene region in Parkinson disease subtypes

The microtubule-associated protein tau (MAPT) region has been conceptualized as a model of the interaction between genetics and functional disease outcomes in neurodegenerative disorders, such as Parkinson disease (PD). Indeed, haplotype-specific differences in expression and alternative splicing of MAPT transcripts affect cellular functions at different levels, increasing susceptibility to a range of neurodegenerative processes. In order to evaluate a possible link between MAPT variants, PD risk and PD motor phenotype, we analyzed the genetic architecture of MAPT in a cohort of PD patients. We observed a statistically significant association between the H1 haplotype and PD risk (79.5 vs 69.5%; χ(2) = 9.9; OR, 1.7; 95% CI, 1.2-2.4; p = 0.002). The effect was more evident in non tremor dominant (TD) PD subjects (NTD-PD) (82 vs 69.5%; χ(2) = 13.6; OR, 2.03; 95% CI, 1.4-3; p = 0.0003), while no difference emerged between PD subgroup of tremor dominant patients (TD-PD) and control subjects. Examination of specific intra-H1 variations showed that the H1h subhaplotype was overrepresented in NTD-PD patients compared with controls (p = 0.007; OR, 2.9; 95% CI, 1.3-6.3). Although we cannot exclude that MAPT variation may be associated with ethnicity, our results may support the hypothesis that MAPT H1 clade and a specific H1 subhaplotype influence the risk of PD and modulate the clinical expression of the disease, including motor phenotype

DNA methylation of the 5'-UTR DAT 1 gene in Parkinson's disease patients

The involvement of epigenetics mechanisms in the transcriptional regulation of key genes has been investigated in the initiation and progression of neurodegenerative disorders, including Parkinson's disease (PD). Among others, we, here, focused the attention on the dopamine transporter (DAT) gene playing a critical role in maintaining the integrity of dopaminergic neurons

Paternal alcohol exposure in mice alters brain NGF and BDNF and increases ethanol-elicited preference in male offspring

Ethanol (EtOH) exposure during pregnancy induces cognitive and physiological deficits in the offspring. However, the role of paternal alcohol exposure (PAE) on offspring EtOH sensitivity and neurotrophins has not received much attention. The present study examined whether PAE may disrupt nerve growth factor (NGF) and/or brain-derived neurotrophic factor (BDNF) and affect EtOH preference/rewarding properties in the male offspring. CD1 sire mice were chronically addicted for EtOH or administered with sucrose. Their male offsprings when adult were assessed for EtOH preference by a conditioned place preference paradigm. NGF and BDNF, their receptors (p75NTR, TrkA and TrkB), dopamine active transporter (DAT), dopamine receptors D1 and D2, pro-NGF and pro-BDNF were also evaluated in brain areas. PAE affected NGF levels in frontal cortex, striatum, olfactory lobes, hippocampus and hypothalamus. BDNF alterations in frontal cortex, striatum and olfactory lobes were found. PAE induced a higher susceptibility to the EtOH rewarding effects mostly evident at the lower concentration (0.5 g/kg) that was ineffective in non-PAE offsprings. Moreover, higher ethanol concentrations (1.5 g/kg) produced an aversive response in PAE animals and a significant preference in non-PAE offspring. PAE affected also TrkA in the hippocampus and p75NTR in the frontal cortex. DAT was affected in the olfactory lobes in PAE animals treated with 0.5 g/kg of ethanol while no differences were found on D1/D2 receptors and for pro-NGF or pro-BDNF. In conclusion, this study shows that: PAE affects NGF and BDNF expression in the mouse brain; PAE may induce ethanol intake preference in the male offspring

Cladribine and ocrelizumab induce differential miRNA profiles in peripheral blood mononucleated cells from relapsing–remitting multiple sclerosis patients

Background and objectivesMultiple sclerosis (MS) is a chronic, progressive neurological disease characterized by early-stage neuroinflammation, neurodegeneration, and demyelination that involves a spectrum of heterogeneous clinical manifestations in terms of disease course and response to therapy. Even though several disease-modifying therapies (DMTs) are available to prevent MS-related brain damage—acting on the peripheral immune system with an indirect effect on MS lesions—individualizing therapy according to disease characteristics and prognostic factors is still an unmet need. Given that deregulated miRNAs have been proposed as diagnostic tools in neurodegenerative/neuroinflammatory diseases such as MS, we aimed to explore miRNA profiles as potential classifiers of the relapsing–remitting MS (RRMS) patients’ prospects to gain a more effective DMT choice and achieve a preferential drug response.MethodsA total of 25 adult patients with RRMS were enrolled in a cohort study, according to the latest McDonald criteria before (pre-cladribine, pre-CLA; pre-ocrelizumab, pre-OCRE, time T0) and after high-efficacy DMTs, time T1, 6 months post-CLA (n = 10, 7 F and 3 M, age 39.0 ± 7.5) or post-OCRE (n = 15, 10 F and 5 M, age 40.5 ± 10.4) treatment. A total of 15 age- and sex-matched healthy control subjects (9 F and 6 M, age 36.3 ± 3.0) were also selected. By using Agilent microarrays, we analyzed miRNA profiles from peripheral blood mononuclear cells (PBMC). miRNA–target networks were obtained by miRTargetLink, and Pearson’s correlation served to estimate the association between miRNAs and outcome clinical features.ResultsFirst, the miRNA profiles of pre-CLA or pre-OCRE RRMS patients compared to healthy controls identified modulated miRNA patterns (40 and seven miRNAs, respectively). A direct comparison of the two pre-treatment groups at T0 and T1 revealed more pro-inflammatory patterns in the pre-CLA miRNA profiles. Moreover, both DMTs emerged as being capable of reverting some dysregulated miRNAs toward a protective phenotype. Both drug-dependent miRNA profiles and specific miRNAs, such as miR-199a-3p, miR-29b-3p, and miR-151a-3p, emerged as potentially involved in these drug-induced mechanisms. This enabled the selection of miRNAs correlated to clinical features and the related miRNA–mRNA network.DiscussionThese data support the hypothesis of specific deregulated miRNAs as putative biomarkers in RRMS patients’ stratification and DMT drug response