| 1. |
- Bazov, Igor, 1973-, et al.
(författare)
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Neuronal Expression of Opioid Gene is Controlled by Dual Epigenetic and Transcriptional Mechanism in Human Brain
- 2018
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Ingår i: Cerebral Cortex. - : Oxford University Press (OUP). - 1047-3211 .- 1460-2199. ; 28:9, s. 3129-3142
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Tidskriftsartikel (refereegranskat)abstract
- Molecular mechanisms that define patterns of neuropeptide expression are essential for the formation and rewiring of neural circuits. The prodynorphin gene (PDYN) gives rise to dynorphin opioid peptides mediating depression and substance dependence. We here demonstrated that PDYN is expressed in neurons in human dorsolateral prefrontal cortex (dlPFC), and identified neuronal differentially methylated region in PDYN locus framed by CCCTC-binding factor binding sites. A short, nucleosome size human-specific promoter CpG island (CGI), a core of this region may serve as a regulatory module, which is hypomethylated in neurons, enriched in 5-hydroxymethylcytosine, and targeted by USF2, a methylation-sensitive E-box transcription factor (TF). USF2 activates PDYN transcription in model systems, and binds to nonmethylated CGI in dlPFC. USF2 and PDYN expression is correlated, and USF2 and PDYN proteins are co-localized in dlPFC. Segregation of activatory TF and repressive CGI methylation may ensure contrasting PDYN expression in neurons and glia in human brain.
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| 2. |
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| 3. |
- Bazov, Igor, et al.
(författare)
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The endogenous opioid system in human alcoholics : molecular adaptations in brain areas involved in cognitive control of addiction
- 2013
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Ingår i: Addiction Biology. - : Wiley. - 1355-6215 .- 1369-1600. ; 18:1, s. 161-169
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Tidskriftsartikel (refereegranskat)abstract
- The endogenous opioid system (EOS) plays a critical role in addictive processes. Molecular dysregulations in this system may be specific for different stages of addiction cycle and neurocircuitries involved and therefore may differentially contribute to the initiation and maintenance of addiction. Here we evaluated whether the EOS is altered in brain areas involved in cognitive control of addiction including the dorsolateral prefrontal cortex (dl-PFC), orbitofrontal cortex (OFC) and hippocampus in human alcohol-dependent subjects. Levels of EOS mRNAs were measured by quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and levels of dynorphins by radioimmunoassay (RIA) in post-mortem specimens obtained from 14 alcoholics and 14 controls. Prodynorphin mRNA and dynorphins in dl-PFC, κ-opioid receptor mRNA in OFC and dynorphins in hippocampus were up-regulated in alcoholics. No significant changes in expression of proenkephalin, and µ- and δ-opioid receptors were evident; pro-opiomelanocortin mRNA levels were below the detection limit. Activation of the κ-opioid receptor by up-regulated dynorphins in alcoholics may underlie in part neurocognitive dysfunctions relevant for addiction and disrupted inhibitory control.
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| 4. |
- Madani, Fatemeh, et al.
(författare)
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Perturbations of model membranes induced by pathogenic dynorphin A mutants causing neurodegeneration in human brain
- 2011
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 411:1, s. 111-114
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Tidskriftsartikel (refereegranskat)abstract
- Several effects of the endogenous opioid peptide dynorphin A (Dyn A) are not mediated through the opioid receptors. These effects are generally excitatory, and result in cell loss and induction of chronic pain and paralysis. The mechanism(s) is not well defined but may involve formation of pores in cellular membranes. In the 17-amino acid peptide Dyn A we have recently identified L5S, R6W, and R9C mutations that cause the dominantly inherited neurodegenerative disorder Spinocerebellar ataxia type 23. To gain further insight into non-opioid neurodegenerative mechanism(s), we studied the perturbation effects on lipid bilayers of wild type Dyn A and its mutants in large unilamellar phospholipid vesicles encapsulating the fluorescent dye calcein. The peptides were found to induce calcein leakage from uncharged and negatively charged vesicles to different degrees, thus reflecting different membrane perturbation effects. The mutant Dyn A R6W was the most potent in producing leakage with negatively charged vesicles whereas Dyn A L5S was virtually inactive. The overall correlation between membrane perturbation and neurotoxic response [3] suggests that pathogenic Dyn A actions may be mediated through transient pore formation in lipid domains of the plasma membrane.
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| 5. |
- Taqi, Malik Mumtaz, et al.
(författare)
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Conformation Effects of CpG Methylation on Single-Stranded DNA Oligonucleotides : Analysis of the Opioid Peptide Dynorphin-Coding Sequences
- 2012
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:6, s. e39605-
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Tidskriftsartikel (refereegranskat)abstract
- Single-stranded DNA (ssDNA) is characterized by high conformational flexibility that allows these molecules to adopt a variety of conformations. Here we used native polyacrylamide gel electrophoresis (PAGE), circular dichroism (CD) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy to show that cytosine methylation at CpG sites affects the conformational flexibility of short ssDNA molecules. The CpG containing 37-nucleotide PDYN (prodynorphin) fragments were used as model molecules. The presence of secondary DNA structures was evident from differences in oligonucleotide mobilities on PAGE, from CD spectra, and from formation of A-T, G-C, and non-canonical G-T base pairs observed by NMR spectroscopy. The oligonucleotides displayed secondary structures at 4 degrees C, and some also at 37 degrees C. Methylation at CpG sites prompted sequence-dependent formation of novel conformations, or shifted the equilibrium between different existing ssDNA conformations. The effects of methylation on gel mobility and base pairing were comparable in strength to the effects induced by point mutations in the DNA sequences. The conformational effects of methylation may be relevant for epigenetic regulatory events in a chromatin context, including DNA-protein or DNA-DNA recognition in the course of gene transcription, and DNA replication and recombination when double-stranded DNA is unwinded to ssDNA.
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| 6. |
- Taqi, Malik Mumtaz, 1983-
(författare)
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Mechanisms of Prodynorphin Gene Dysregulation in the Brain of Human Alcoholics
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The endogenous opioid system (EOS) including dynorphin opioid peptides and κ-opioid receptor (KOR) plays a critical role in alcohol dependence. Aims of the thesis were to evaluate whether the EOS undergoes molecular adaptations in brain areas involved in cognitive control of addiction in human alcohol dependent subjects, and to analyze the impact of genetic and epigenetic factors on these adaptive changes. The main findings were that (1) the dynorphin/KOR system including PDYN mRNA and dynorphins in the dorsolateral prefrontal cortex (dl-PFC), dynorphins in the hippocampus, and KOR mRNA in the orbitofrontal cortex (OFC), is upregulated in human alcoholics. No other significant changes in the EOS were found. (2) Three PDYN single nucleotide polymorphisms (SNPs), which show the most significant association with alcohol dependence, form CpG sites that are methylated in human brain at different levels. Methylation of the C, non-risk variant of the 3’-untranslated region (3’-UTR) SNP (rs2235749; C>T) was increased in dl-PFC and positively correlated with dynorphins. The DNA-binding factor that differentially targeted the T, risk allele and methylated and unmethylated C allele of this SNP was identified in human brain. We hypothesize that influences of the genetic, epigenetic and environmental factors may be integrated through alterations in methylation of the PDYN 3’jUTR CpG/SNP and, as a consequence, affect PDYN transcription and vulnerability to develop alcohol dependence. (3) The principal component analysis suggested that PDYN expression in the dl-PFC may be related to alcoholism, while in the hippocampus may depend on the genotype of the PDYN promoter SNP (rs1997794; T>C). The T, low risk allele of this SNP resides within non-canonical AP-1-binding element and may be targeted by JUND and FOSB proteins, the dominant AP-1 constituents in the human brain. The T to C transition abrogated AP-1 binding. The impact of genetic variations on PDYN transcription may be relevant for diverse adaptive responses of this gene to alcohol. (4) It was proposed that PDYN transcription may be regulated by intragenic DNA regulatory elements controlling the DNA-protein interactions through formation of non-canonical DNA secondary structures. The dynorphin-encoding sequence in PDYN was found to have potential to form such DNA structure in vitro, and this formation was affected by CpG methylation in this region. This methylation sensitive non-canonical DNA structure formation may be involved in regulation of initiation of PDYN transcription from alternative start sites located within this region, or in splicing of non-canonical mRNA. In conclusion, the dynorphin/KOR system has been identified as the site of robust adaptive changes associated with alcohol dependence in the areas of human brain involved in cognitive control of addiction. Regulation of PDYN was found to be brain area specific, apparently affected by the genetic and epigenetic factors, and possibly dependent on the internal properties of the gene such as its ability to form non-canonical DNA secondary structures.
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| 7. |
- Taqi, Malik Mumtaz, et al.
(författare)
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Prodynorphin CpG-SNPs associated with alcohol dependence : elevated methylation in the brain of human alcoholics
- 2011
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Ingår i: Addiction Biology. - : Wiley. - 1355-6215 .- 1369-1600. ; 16:3, s. 499-509
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Tidskriftsartikel (refereegranskat)abstract
- The genetic, epigenetic and environmental factors may influence the risk for neuropsychiatric disease through their effects on gene transcription. Mechanistically, these effects may be integrated through regulation of methylation of CpG dinucleotides overlapping with single-nucleotide polymorphisms (SNPs) associated with a disorder. We addressed this hypothesis by analyzing methylation of prodynorphin (PDYN) CpG-SNPs associated with alcohol dependence, in human alcoholics. Postmortem specimens of the dorsolateral prefrontal cortex (dl-PFC) involved in cognitive control of addictive behavior were obtained from 14 alcohol-dependent and 14 control subjects. Methylation was measured by pyrosequencing after bisulfite treatment of DNA. DNA binding proteins were analyzed by electromobility shift assay. Three PDYN CpG-SNPs associated with alcoholism were found to be differently methylated in the human brain. In the dl-PFC of alcoholics, methylation levels of the C, non-risk variant of 3'-untranslated region (3'-UTR) SNP (rs2235749; C > T) were increased, and positively correlated with dynorphins. A DNA-binding factor that differentially targeted the T, risk allele and methylated and unmethylated C allele of this SNP was identified in the brain. The findings suggest a causal link between alcoholism-associated PDYN 3'-UTR CpG-SNP methylation, activation of PDYN transcription and vulnerability of individuals with the C, non-risk allele(s) to develop alcohol dependence.
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| 8. |
- Taqi, Malik Mumtaz, et al.
(författare)
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Prodynorphin promoter SNP associated with alcohol dependence forms noncanonical AP-1 binding site that may influence gene expression in human brain
- 2011
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Ingår i: Brain Research. - : Elsevier BV. - 0006-8993 .- 1872-6240. ; 1385, s. 18-25
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Tidskriftsartikel (refereegranskat)abstract
- Single nucleotide polymorphism (rs1997794) in promoter of the prodynorphin gene (PDYN) associated with alcohol-dependence may impact PDYN transcription in human brain. To address this hypothesis we analyzed PDYN mRNA levels in the dorsolateral prefrontal cortex (dl-PFC) and hippocampus, both involved in cognitive control of addictive behavior and PDYN promoter SNP genotype in alcohol-dependent and control human subjects. The principal component analysis suggested that PDYN expression in the dl-PFC may be related to alcoholism, while in the hippocampus may depend on the genotype. We also demonstrated that the T, low risk SNP allele resides within noncanonical AP-1-binding element that may be targeted by JUND and FOSS proteins, the dominant AP-1 constituents in the human brain. The T to C transition abrogated AP-1 binding. The impact of genetic variations on PDYN transcription may be relevant for diverse adaptive responses of this gene to alcohol.
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