Functional characterization of the promoter region of human TNFAIP1 gene

Tumor necrosis factor, alpha-induced protein 1 (TNFAIP1) is an immediate-early response gene of endothelium induced by TNF alpha. However, little is really known concerning the TNFAIP1 expression regulation. To better understand how TNFAIP1 expression is regulated, we functionally characterized the promoter region of human TNFAIP1 gene. Deletion mutation analysis, gel electrophoretic mobility shift, and site-directed mutagenesis assays allowed the identification of one functional Sp1-binding site within the human TNFAIP1 core promoter region. Moreover, chromatin immunoprecipitation analysis indicated that Sp1 was associated in vivo with the TNFAIP1 promoter. Further, Sp1 overexpression enhanced TNFAIP1 promoter activity. These findings suggest that Sp1 is implicated in the control of basal TNFAIP1 gene expression. Accordingly, Sp1 is supposed to be involved in the elevation of TNFAIP1 in response to TNF alpha induction, and thus participate in inflammation-associated angiogenesis.     

Molecular cloning, characterization and association analysis of the promoter region of the bovine CDK6 gene

Cyclin-dependent kinase 6 (CDK6) is a key element of D-type cyclin holoenzymes. It is involved in the regulation of the G1-phase of the cell cycle and is considered to be an important candidate gene for selection of body measurement traits through marker-assisted selection. We cloned the promoter sequence of this gene in bovines and found it to share high similarity with that of the human CDK6 promoter. A 2271-bp sequence upstream of the start codon in the bovine CDK6 5'-flanking sequence is rich in GC; it lacks consensus TATA or CAAT box, but it contains several MZF1 binding sites. Other potential cis-regulatory elements were found in the 5'-flanking region, including CdxA, SRY, p300, GATA-1, and deltaE. Allele frequencies were also analyzed in various cattle breeds (Qinchuan, Qinchuan improvement steers, Nanyang, Jiaxian red, Xia'nan, Luxi, Simmental and Luxi crossbred steers, and Xuelong) and association with a selected single nucleotide polymorphism (SNP) was calculated. The T-1075C SNP in the promoter was found to be significantly associated with body length and heart girth. This SNP marker was found to be significantly associated with body length and the heart girth in 737 individuals. We conclude that this SNP of the CDK6 gene has potential as a genetic marker for important body traits in bovine reproduction and breeding.     

Functional characterization of the thi1 promoter region from Arabidopsis thaliana

The Arabidopsis thaliana THI1 protein is involved in thiamine biosynthesis and is targeted to both chloroplasts and mitochondria by N-terminal control regions. To investigate thi1 expression, a series of thi1 promoter deletions were fused to the beta-glucuronidase (GUS) reporter gene. Transgenic plants were generated and expression patterns obtained under different environmental conditions. The results show that expression derived from the thi1 promoter is detected early on during development and continues throughout the plant's life cycle. High levels of GUS expression are observed in both shoots and roots during vegetative growth although, in roots, expression is restricted to the vascular system. Deletion analysis of the thi1 promoter region identified a region that is responsive to light. The smallest fragment (designated Pthi322) encompasses 306 bp and possesses all the essential signals for tissue specificity, as well as responsiveness to stress conditions such as sugar deprivation, high salinity, and hypoxia.     

Functional IL-18 promoter gene polymorphisms in Tunisian nasopharyngeal carcinoma patients

Objectives: There is growing evidence suggesting that IL-18 levels may affect individual to virus-associated neoplasia and that single nucleotide polymorphisms (SNPs) within the gene may influence its production. In this study we wanted to know whether IL-18 polymorphisms at positions −607 C/A and −137 G/A are associated with susceptibility and/or are markers of nasopharyngeal carcinoma (NPC) prognosis. Methods: Using the restriction fragment length polymerase chain reaction (RFLP-PCR), 163 Tunisian patients and 164 healthy controls were genotyped. Results: No significant association was found between each studied polymorphism and NPC. However, we noted that the −607 A allele, which is associated with lower IL-18 production, increased the risk of advanced tumor stages (OR = 3.59; P = 0.017) and that this risk was more pronounced among the older patient’s age at onset (OR = 3.85; P = 0.012). Moreover, the significant difference in CA/GG haplotype frequency distribution between young and older patients supported the idea that NPC disease has biologically different features between age sub-groups. Conclusion: Functional IL-18 gene polymorphisms do not influence the susceptibility to NPC in Tunisians but may contribute to disease onset and aggressiveness.     

Functional profile of the human fetal gamma-globin gene upstream promoter region.

We performed a systematic functional analysis of the human gamma-globin promoter to identify its activator domains. We used a panel of truncation and scanning mutants as well as transfection in human K562 fetal erythroid cells. The various mutations produced relatively small changes in promoter function in both transient and stable transfection assays. The CACCC region and the region containing the binding sites for protein GATA-1 behaved as activator domains. We also obtained evidence for a minor activator site in the - 200 to - 190 region. The results are consistent with the interpretation that gamma-globin gene regulation may occur in part through multiple small effects of promoter elements.     

Functional significance of genetic polymorphisms

Natural genetic polymorphisms are gifts from nature and sources of variations at all levels. The postgenomic era permits new perspectives on interpreting genetic polymorphisms and also poses challenges for scientists to answer system questions. Rather than a comprehensive coverage of genetic polymorphisms upto-date, this review attempts to present some of the results in a somewhat coherent manner to highlight the needs and potentials of pertinent studies.