Initiator-Directed Transcription: Fission Yeast Nmtl Initiator Directs Preinitiation Complex Formation and Transcriptional Initiation.

The initiator element is a core promoter element encompassing the transcription start site, which is found in yeast, Drosophila, and human promoters. This element is observed in TATA-less promoters. Several studies have defined transcription factor requirements and additional cofactors that are needed for transcription initiation of initiator-containing promoters. However, those studies have been performed with additional core promoters in addition to the initiator. In this work, we have defined the pathway of preinitiation complex formation on the fission yeast nmt1 gene promoter, which contains a functional initiator with striking similarity to the initiator of the human dihydrofolate reductase (hDHFR) gene and to the factor requirement for transcription initiation of the nmt1 gene promoter. The results show that the nmt1 gene promoter possesses an initiator encompassing the transcription start site, and several conserved base positions are required for initiator function. A preinitiation complex formation on the nmt1 initiator can be started by TBP/TFIIA or TBP/TFIIB, but not TBP alone, and afterwards follows the same pathway as preinitiation complex formation on TATA-containing promoters. Transcription initiation is dependent on the general transcription factors TBP, TFIIB, TFIIE, TFIIF, TFIIH, RNA polymerase II, Mediator, and a cofactor identified as transcription cofactor for initiator function (TCIF), which is a high-molecular-weight protein complex of around 500 kDa. However, the TAF subunits of TFIID were not required for the nmt1 initiator transcription, as far as we tested. We also demonstrate that other initiators of the nmt1/hDHFR family can be transcribed in fission yeast whole-cell extracts.

Genetic Polymorphisms Associated with Thrombotic Disease Comparison of Two Territories: Myocardial Infarction and Ischemic Stroke.

BACKGROUND AND PURPOSE: The thrombin-activatable fibrinolysis inhibitor (TAFI) is an important inhibitor of fibrinolysis and plays a critical role in the pathogenesis of arterial thrombosis; genetic polymorphisms of the TAFI gene affect its activity and increase the risk of thrombosis. Moreover, studies in young patients are still scarce. The aim was to examine the contribution of the Thr325Ile and Ala147Thr polymorphisms with ST acute myocardial infarction (STEMI) or idiopathic ischemic stroke (IIS) in the young Mexican population. METHODS: A total of 244 patients with STEMI ≤45 years of age and 244 controls. In a second study, 250 patients with IIS ≤45 years of age were recruited, including 250 controls. In both studies, cases and controls were matched by age and sex. The polymorphisms were determined in all participants by PCR-RFLP. RESULTS: There was significant difference in the Thr325Ile genotype distribution (P = 0.001) and allele frequency (P = 0.001) between STEMI and control groups, but no difference in the Ala147Thr genotype distribution (P = 0.24) and allele frequency (P = 0.46), neither in the Thr325Ile genotype distribution (P = 0.25) nor in the Ala147Thr genotype distribution (P = 0.46) or their allele frequencies; there was significant difference between IIS and the control group. There were independent factors for STEMI: the Ile allele (P = 0.01), type 2 diabetes mellitus (P = 0.001), hypertension (P = 0.001), smoking (P = 0.001), dyslipidemia (P = 0.001), and family history of atherothrombotic disease (P = 0.001). The independent factors for IIS were hypertension (P = 0.001), smoking (P < 0.01), and family history of atherothrombotic disease (P < 0.01). CONCLUSIONS: The Thr325Ile polymorphism, but no Ala147Thr polymorphism, represents an independent risk factor for STEMI in the young Mexican population.

Identification of the gene encoding the TATA box-binding protein-associated factor 1 (TAF1) and its putative role in the heat shock response in the protozoan parasite Entamoeba histolytica.

Transcription factor IID (TFIID) is a cornerstone in the transcription initiation in eukaryotes. It is composed of TBP and approximately 14 different subunits named TBP-associated factors (TAFs). TFIID has a key role in transcription of many genes involved in cell proliferation, cell growth, cell cycle, cell cycle checkpoint, and various other processes as well. Entamoeba histolytica, the protozoan parasite responsible for human amoebiasis, represents a major global health concern. Our research group has previously reported the genes coding the TATA box-binding protein (EhTBP) and TBP-related factor 1 (EhTRF1), which displayed different mRNA levels in trophozoites under different stress conditions. In this work, we identified the TBP-associated factor 1 (Ehtaf1) gene in the E. histolytica genome, which possess a well-conserved DUF domain and a Bromo domain located in the middle and C-terminus of the protein, respectively. The EhTAF1-DUF domain tertiary structure is similar to the corresponding HsTAF1 DUF domain. RT-qPCR experiments with RNA isolated from trophozoites harvested at different time points of the growth curve and under different stress conditions revealed that the Ehtaf1 gene was found slightly upregulated in the death phase of growth curve, but under heat shock stress, it was found upregulated 10 times, suggesting that Ehtaf1 might have an important role in the heat shock stress response. We also found that EhTAF1 is expressed in the nucleus and cytoplasm at 37 °C, but under heat shock stress, it is overexpressed in both the nucleus and cytoplasm, and partially colocalized with EhHSP70 in cytoplasm.