Prediction and verification of the influence of the rs367781716 SN P on the interaction of ТАТА -binding protein with the promoter of the human АВСА9 gene

The high-throughput sequencing project “1 000 Genomes” made it possible to catalog and utilize genetic loci and single nucleotide polymorphisms (SNPs) in medicine. Analysis of SNP markers (significantly frequent differences of individual genomes of patients from the reference human genome) allows physicians to optimize treatment. On the other hand, tens of millions of unannotated SNPs correspond to a gigantic number of false positive (false negative) candidate SNP markers that are selected by computer methods for comparison of their frequency in patients with that in healthy people. This approach contributes to undervaluation of clinically relevant SNPs and to unnecessary computational expenses (on verification of neutral SNPs). Preclinical empirical verification of possible candidate SNP markers may eliminate neutral SNPs from the dataset. In the present study, we found, using the SNP_TATA_Comparator web service, the unannotated SNP rs367781716: the substitution of ancestral T (health) with minor C at position –37 before the transcription initiation site of the АВСА9 gene. This SNP significantly reduces affinity of TATAbinding protein (TBP) for this gene’s promoter and corresponds to a deficiency (low protein level) of the АВСА9 gene product (the transporter ATP-binding cassette A9) in patients with the –37C allele. For preclinical empirical verification of rs367781716, we used an electrophoretic mobility shift assay (EMSA) to measure the rates of formation (ka) and decay (kd) of the complexes of TBP with an oligonucleotide matching either allele –37C or –37T of the АВСА9 gene. We found that the rate of formation (ka) of the TBP/TATA complex for the minor allele is 2.4-fold lower than that for the ancestral allele. We calculated the empirical value of the change in the equilibrium constant of dissociation (KD = kd /ka), which characterizes binding affinity of TBP for a promoter containing the ТАТА box. This empirical value matched the value predicted by SNP_ТАТА _Comparator within the margin of error of the measurements and calculations. We also determined the half-life and Gibbs free energy of the complex of TBP with the АВСА9 promoter. Possible phenotypic manifestations of the candidate SNP marker rs367781716 are discussed

Modeling the Function of TATA Box Binding Protein in Transcriptional Changes Induced by HIV-1 Tat in Innate Immune Cells and the Effect of Methamphetamine Exposure

Innate immune cells are targets of HIV-1 infection in the Central Nervous System (CNS), generating neurological deficits. Infected individuals with substance use disorders as co-morbidities, are more likely to have aggravated neurological disorders, higher CNS viral load and inflammation. Methamphetamine (Meth) is an addictive stimulant drug, commonly among HIV+ individuals. The molecular basis of HIV direct effects and its interactions with Meth in host response, at the gene promoter level, are not well understood. The main HIV-1 peptide acting on transcription is the transactivator of transcription (Tat), which promotes replication by recruiting a Tata-box binding protein (TBP) to the virus long-terminal repeat (LTR). We tested the hypothesis that Tat can stimulate host gene expression through its ability to increase TBP, and thus promoting its binding to promoters that bear Tata-box binding motifs. Genes with Tata-box domains are mainly inducible, early response, and involved in inflammation, regulation and metabolism, relevant in HIV pathogenesis. We also tested whether Tat and Meth interact to trigger the expression of Tata-box bearing genes. The THP1 macrophage cell line is a well characterized innate immune cell system for studying signal transduction in inflammation. These cells are responsive to Tat, as well as to Meth, by recruiting RNA Polymerase (RNA Pol) to inflammatory gene promoters, within 15 min of stimulation (1). THP-1 cells, including their genetically engineered derivatives, represent valuable tools for investigating monocyte structure and function in both health and disease, as a consistent system (2). When differentiated, they mimic several aspects of the response of macrophages, and innate immune cells that are the main HIV-1 targets within the Central Nervous System (CNS). THP1 cells have been used to characterize the impact of Meth and resulting neurotransmitters on HIV entry (1), mimicking the CNS micro-environment. Integrative consensus sequence analysis in genes with enriched RNA Pol, revealed that TBP was a major transcription factor in Tat stimulation, while the co-incubation with Meth shifted usage to a distinct and diversified pattern. For validating these findings, we engineered a THP1 clone to be deficient in the expression of all major TBP splice variants, and tested its response to Tat stimulation, in the presence or absence of Meth. Transcriptional patterns in TBP-sufficient and deficient clones confirmed TBP as a dominant transcription factor in Tat stimulation, capable of inducing genes with no constitutive expression. However, in the presence of Meth, TBP was no longer necessary to activate the same genes, suggesting promoter plasticity. These findings demonstrate TBP as mechanism of host-response activation by HIV-1 Tat, and suggest that promoter plasticity is a challenge imposed by co-morbid factors such as stimulant drug addiction. This may be one mechanism responsible for limited efficacy of therapeutic approaches in HIV+ Meth abusers

SNPS in the HIV-1 tata box and the aids pandemic

Evolutionary trends have been examined in 146 HIV-1 forms (2662 copies, 2311 isolates) polymorphic for the TATA box using the "DNA sequence→affinity for TBP" regression (TBP is the TATA binding protein). As a result, a statistically significant excess of low-affinity TATA box HIV-1 variants corresponding to a low level of both basal and TAT-dependent expression and, consequently, slow replication of HIV-1 have been detected. A detailed analysis revealed that the excess of slowly replicating HIV-1 is associated with the subtype E-associated TATA box core sequence "CATAAAA". Principal Component Analysis performed on 2662 HIV-1 TATA box copies in 70 countries revealed the presence of two principal components, PC1 (75.7% of the variance) and PC2 (23.3% of the variance). They indicate that each of these countries is specifically associated with one of the following trends in HIV-1 evolution: neutral drift around the normal TATA box; neutral drift around the slowly replicating TATA box core sequence (phylogenetic inertia); an adaptive increase in the frequency of the slowly replicating form. © 2010 Imperial College Press