Biomedical subjects

Tiebing Liang

Publications and source records attributed to Tiebing Liang.

5 recordsLinked to original sources

PubMed2006

Regulation of alpha-synuclein expression in alcohol-preferring and -non preferring rats.

The alpha-synuclein (Snca) gene is expressed at higher levels in alcohol-naïve, inbred alcohol-preferring (iP) rats than in alcohol-non preferring (iNP) rats. Snca modulates dopamine transmission and the dopamineregic system, which play a role in mediating the rewarding properties of alcohol consumption. Thus, understanding regulation of Snca gene expression could provide insight into the relationship of Snca and alcohol consumption. To study regulation of rat Snca expression, 1,912 bp of the iP and iNP 5'-regions were cloned and sequenced. 5'-rapid amplification of cDNA ends (RACE), primer extension and RT-PCR mapped three transcription start site clusters (clusters TSS1, TSS2 and TSS3), suggesting that the Snca proximal promoter region has a complex architecture. This proximal promoter region has three TATA-less core promoters containing SP1 binding sites, initiator elements and downstream core promoter elements, which are often located in such promoters. Snca-luc constructs transiently transfected into SK-N-SH neuroblastoma cells showed that the region from - 1,912 to - 1,746 contained a strong core promoter, and that the entire approximately 2 kb region had significant promoter activity. Five polymorphisms identified between the iP and iNP in the proximal promoter region did not influence differential expression between the strains. In contrast, a single nucleotide polymorphism (SNP) at + 679 in the 3'-untranslated region (UTR) resulted in a 1.3-fold longer half-life of iP mRNA compared with iNP mRNA, which is consistent with the differential expression observed between the iP and iNP strains. These results suggest that regulation of rat Snca gene expression is complex and may contribute to alcohol preference in the iP rats.

3' Untranslated Regions↗

PubMed2005

Expression profiling and QTL analysis: a powerful complementary strategy in drug abuse research.

Alcoholism is a complex disease exhibiting a multifactorial mode of transmission. To simplify the genetic and phenotypic complexity of the alcoholic phenotype, alcohol-preferring (P) and -non-preferring (NP) rats were developed on the basis of alcohol preference and consumption as an animal model of alcoholism. Total gene expression analysis (TOGA) and quantitative trait loci (QTL) analysis were applied to selectively bred, inbred P and NP rats as complementary studies to identify genetic factors that contribute to alcohol preference and consumption. TOGA analysis was utilized to screen for differential expression in several brain regions involved in the mesocorticolimbic dopamine (DA) system. Genes exhibiting differences in expression were then screened for an association to the alcohol preference phenotype, the quantitative trait of a previously identified QTL. By evaluating differences in gene expression for linkage to a quantitative trait, this combined approach was implemented to identify alpha-synuclein, a candidate gene for alcohol preference.

Animals↗

PubMed2004

Glutathione S-transferase 8-8 expression is lower in alcohol-preferring than in alcohol-nonpreferring rats.

OBJECTIVE: A primary focus of alcohol research is to provide novel targets for alcohol treatment by identifying genes that predispose individuals to drink alcohol. Animal models of alcoholism developed by selective breeding are invaluable tools to elucidate both the genetic nature and the underlying biological mechanisms that contribute to alcohol dependence. These selected lines (high alcohol preferring and low alcohol preferring) display phenotypic and genetic differences that can be studied to further our understanding of alcohol preference and related genetic traits. By combining molecular techniques, genetic and physiological factors that underlie the cause of alcoholism can be identified. METHODS: Total gene expression analysis was used to identify genes that are differentially expressed in specific brain regions between alcohol-naive, inbred alcohol-preferring (iP) and -nonpreferring (iNP) rats. Quantitative reverse transcriptase-polymerase chain reaction, in situ hybridization, Western blot, and sequence analysis were used to further characterize rat glutathione S-transferase 8-8 (rGST 8-8). RESULTS: Lower expression of rGST 8-8 mRNA was observed in discrete brain regions of iP compared with iNP animals, and these expression differences were confirmed. To determine additional expression patterns of rGST 8-8, we used in situ hybridization. Rat GST 8-8 was highly expressed in hippocampus, the choroid plexus of the dorsal third ventricle and the lateral ventricle, and ependymal cells along the dorsal third ventricle and the third ventricle. Western blot analysis showed that rGST 8-8 protein levels were lower in the hippocampus and the amygdala of iP compared with iNP. A silent single-nucleotide polymorphism in the coding region and three single-nucleotide polymorphisms in the 3'-UTR were identified in the rGST 8-8 cDNA. CONCLUSION: There is regional variation of rGST 8-8 expression in the brain, at both the mRNA and protein level, and the iP strain has lower innate rGST 8-8 levels than the iNP strain in discrete brain regions.

Alcohol Drinking↗

PubMed2003

alpha-Synuclein maps to a quantitative trait locus for alcohol preference and is differentially expressed in alcohol-preferring and -nonpreferring rats.

Total gene expression analysis (TOGA) was used to identify genes that are differentially expressed in brain regions between the alcohol-naive, inbred alcohol-preferring (iP), and -nonpreferring (iNP) rats. alpha-Synuclein, expressed at >2-fold higher levels in the hippocampus of the iP than the iNP rat, was prioritized for further study. In situ hybridization was used to determine specific brain regions and cells expressing alpha-synuclein in the iP and iNP rats. Similar to alpha-synuclein mRNA levels, protein levels in the hippocampus were higher in iP rats than iNP rats. Higher protein levels were also observed in the caudate putamen of iP rats compared with iNP rats. Sequence analysis identified two single nucleotide polymorphisms in the 3' UTR of the cDNA. The polymorphism was used to map the gene, by using recombination-based methods, to chromosome 4, within a quantitative trait locus for alcohol consumption that was identified in the iP and iNP rats. A nucleotide exchange in the iNP 3' UTR reduced expression of the luciferase reporter gene in SK-N-SH neuroblastoma cells. These results suggest that differential expression of the alpha-synuclein gene may contribute to alcohol preference in the iP rats.

3' Untranslated Regions↗

PubMed2003

Evaluation of aldehyde dehydrogenase 1 promoter polymorphisms identified in human populations.

BACKGROUND: Cytosolic aldehyde dehydrogenase, or ALDH1A1, functions in ethanol detoxification, metabolism of neurotransmitters, and synthesis of retinoic acid. Because the promoter region of a gene can influence gene expression, the ALDH1A1 promoter regions were studied to identify polymorphism, to assess their functional significance, and to determine whether they were associated with a risk for developing alcoholism. METHODS: Sequence analysis was performed in the promoter region by using Asian, Caucasian, and African American subjects. The resulting polymorphisms were assessed for frequency in Asian, Caucasian, Jewish, and African American populations and tested for associations with alcohol dependence in Asian and African American populations of alcoholics and controls. The functional significance of each polymorphism was determined through in vitro expression analysis by using HeLa and HepG2 cells. RESULTS: Two polymorphisms, a 17 base pair (bp) deletion (-416/-432) and a 3 bp insertion (-524), were discovered in the ALDH1A1 promoter region: ALDH1A1*2 and ALDH1A1*3, respectively. ALDH1A1*2 was observed at frequencies of 0.035, 0.023, 0.023, and 0.012 in the Asian, Caucasian, Jewish, and African American populations, respectively. ALDH1A1*3 was observed only in the African American population, at a frequency of 0.029. By using HeLa and HepG2 cells for in vitro expression, the activity of the luciferase reporter gene was significantly decreased after transient transfection of ALDH1A1*3-luciferase compared with the wild-type construct ALDH1A1*1-luciferase. In an African American population, a trend for higher frequencies of the ALDH1A1*2 and ALDH1A1*3 alleles was observed in a population of alcoholics (p = 0.03 and f = 0.12, respectively) compared with the control population. CONCLUSIONS: ALDH1A1*2 and ALDH1A1*3 may influence ALDH1A1 gene expression. Both ALDH1A1*2 and ALDH1A1*3 produce a trend in an African American population that may be indicative of an association with alcoholism; however, more samples are required to validate this observation. The underlying mechanisms contributing to these trends are still unknown.

Adolescent↗