Genomic structure and promoter analysis of human NeuAc alpha2,3Gal beta1,3GalNAc alpha2,6-sialyltransferase (hST6GalNAc IV) gene

The role of sialyltransferases in gynecological malignant tumors

Sialylation is the addition of sialic acids to the terminus of various glycoconjugates, and it is involved in many essential biological processes, such as cell adhesion, signal transduction, immune regulation, etc. The levels of sialylation in a cell are tightly regulated by two groups of enzymes, sialyltransferases (STs, responsible for sialylation) and sialidases (responsible for desialylation). Many studies have reported that the occurrence, development, and survival rates of tumors are significantly associated with STs' abnormal changes. In recent years, the morbidity and mortality rates of gynecological malignant tumors have been continuously rising, which has caused great harm to women's reproduction and health. Abnormal changes of STs in gynecological malignant tumor cell membranes cause the changes of expression of sialic acids, promoting cell migration and, eventually, leading to tumor metastasis. In this review, we outlined the biological characteristics of STs and summarized the expression profiles of 20 STs in different tumors via transcriptome data from Gene Expression Profiling Interactive Analysis (GEPIA) database. Moreover, STs' functions in four common gynecological tumors (ovarian cancer, cervical cancer, endometrial cancer, and gestational trophoblast tumor) were reviewed.

The application of transcriptomic data in the authentication of beef derived from contrasting production systems

BACKGROUND

Differences between cattle production systems can influence the nutritional and sensory characteristics of beef, in particular its fatty acid (FA) composition. As beef products derived from pasture-based systems can demand a higher premium from consumers, there is a need to understand the biological characteristics of pasture produced meat and subsequently to develop methods of authentication for these products. Here, we describe an approach to authentication that focuses on differences in the transcriptomic profile of muscle from animals finished in different systems of production of practical relevance to the Irish beef industry. The objectives of this study were to identify a panel of differentially expressed (DE) genes/networks in the muscle of cattle raised outdoors on pasture compared to animals raised indoors on a concentrate based diet and to subsequently identify an optimum panel which can classify the meat based on a production system.

RESULTS

A comparison of the muscle transcriptome of outdoor/pasture-fed and Indoor/concentrate-fed cattle resulted in the identification of 26 DE genes. Functional analysis of these genes identified two significant networks (1: Energy Production, Lipid Metabolism, Small Molecule Biochemistry; and 2: Lipid Metabolism, Molecular Transport, Small Molecule Biochemistry), both of which are involved in FA metabolism. The expression of selected up-regulated genes in the outdoor/pasture-fed animals correlated positively with the total n-3 FA content of the muscle. The pathway and network analysis of the DE genes indicate that peroxisome proliferator-activated receptor (PPAR) and FYN/AMPK could be implicit in the regulation of these alterations to the lipid profile. In terms of authentication, the expression profile of three DE genes (ALAD, EIF4EBP1 and NPNT) could almost completely separate the samples based on production system (95 % authentication for animals on pasture-based and 100 % for animals on concentrate- based diet) in this context.

CONCLUSIONS

The majority of DE genes between muscle of the outdoor/pasture-fed and concentrate-fed cattle were related to lipid metabolism and in particular β-oxidation. In this experiment the combined expression profiles of ALAD, EIF4EBP1 and NPNT were optimal in classifying the muscle transcriptome based on production system. Given the overall lack of comparable studies and variable concordance with those that do exist, the use of transcriptomic data in authenticating production systems requires more exploration across a range of contexts and breeds.

Housekeeping promoter 5'pcmah-2 of pig CMP-N-acetylneuraminic acid hydroxylase gene for NeuGc expression

In the present study, we isolated pCMAH house-keeping promoter regions (Ph), which are responsible for transcriptional regulation and which are located upstream of the alternative transcript pcmah-2. Luciferase reporter assays using serial construction of each deleted promoter demonstrated that the Ph promoter was highly active in pig-derived kidney PK15. Ph promoter of pcmah lacked a TATA box, but contained three putative Sp1 binding sites. Mutations of these Sp1 binding sites always resulted in the reduction of luciferase activities in Ph-334. In addition, treatment with mithramycin A (25-100 nM) decreased the luciferase activities of the Ph promoters and NeuGc expression in a dose-dependent manner. Electrophoretic mobility shift assay analysis revealed that the probes containing each Sp1 binding site bound to Sp1. Taken together, the results indicate that Sp1 bind to their putative binding sites on the Ph promoter regions of pcmah and positively regulate the promoter activity in pig kidney cells. Interspecies comparison of 5'UTRs and 5'flanking regions shows high homology between pig and cattle, and Sp1 binding sites existing in genomic regions corresponding Ph region are evolutionally conserved.

Expression of the human CMP-NeuAc:GM3 alpha2,8-sialyltransferase (GD3 synthase) gene through the NF-kappaB activation in human melanoma SK-MEL-2 cells

To elucidate the mechanism underlying the regulation of human GD3 synthase gene expression in human melanoma SK-MEL-2 cells, we identified the promoter region of the human GD3 synthase gene. The 5'-rapid amplification of cDNA end (5'-RACE) using mRNA prepared from SK-MEL-2 cells revealed the presence of multiple transcription start sites of human GD3 synthase gene. Promoter analyses of the 5'-flanking region of the human GD3 synthase gene using luciferase gene reporter system showed the strong promoter activity in SK-MEL-2 cells. Deletion study revealed that the region as the core promoter from -1146 to -646 (A of the translational start ATG as position +1) was indispensable for endogenous expression of human GD3 synthase gene. This region lacks apparent TATA and CAAT boxes but contains putative binding sites for transcription factors c-Ets-1, CREB, AP-1 and NF-kappaB. Electrophoretic mobility shift assays using specific competitors, chromatin immunoprecipitation assay and site-directed mutagenesis demonstrated that only NF-kappaB element in this region is required for the promoter activity in SK-MEL-2 cells. These results indicate that NF-kappaB plays an essential role in the transcriptional activity of human GD3 synthase gene essential for GD3 synthesis in SK-MEL-2 cells.

Transcriptional regulation of the human GD3 synthase gene expression in Fas-induced Jurkat T cells: a critical role of transcription factor NF-kappaB in regulated expression

The transcriptional regulation mechanisms involved in the up-regulation of Fas-induced GD3 synthase gene have not yet been elucidated. 5'-Rapid amplification of cDNA end (5'-RACE) using mRNA prepared from Fas-induced Jurkat T cells revealed the presence of multiple transcription start sites of human GD3 synthase gene, and the 5'-end analysis of the longest of its product showed that transcription started from 650 nucleotides upstream of the translational initiation site. Promoter analyses of the 5'-flanking region of the human GD3 synthase gene using luciferase gene reporter system showed strong promoter activity in Fas-induced Jurkat T cells. Deletion study revealed that the region from -1146 to -646 (A of the translational start ATG as position +1) was indispensable for the Fas response. This region lacks apparent TATA and CAAT boxes but contains putative binding sites for transcription factors c-Ets-1, cAMP-responsive element-binding (CREB) protein, activating protein 1 (AP-1), and NF-kappaB. Base-substitution experiment showed that only the NF-kappaB-binding site of putative binding sites is required for the maximal expression induced by Fas. Both DNase I footprint and electrophoretic mobility shift assays with the nuclear extract of Fas-induced Jurkat T cells revealed that NF-kappaB was bound specifically to the probe being mediated by its binding site in the promoter sequence. Taken together, these results indicate that NF-kappaB plays an essential role in the transcriptional activity of human GD3 synthase gene in Fas-induced Jurkat T cells. In addition, the translocation of NF-kappaB-binding protein to nucleus by Fas activation is also crucial for the increased expression of the GD3 synthase gene in Fas-activated Jurkat T cells.

Increased expression of N-acetylglucosaminyltransferase-V in human hepatoma cells by retinoic acid and 1alpha,25-dihydroxyvitamin D3

UDP-N-acetylglucosamine: alpha-6-D-mannoside beta-1,6N-acetylglucosaminyltransferase-V activities were determined in human hepatoma cell lines of Hep3B and HepG2, and also compared with those of normal liver tissues and primary hepatocytes. When GlcNAcbeta1-2Manalpha1-3(GlcNAcbeta1-2Manalpha1-4)(Manbeta1-4GlcNAc-2-amino pyridine (GlcN,GlcN-biant-PA) and UDP-GlcNAc were used as substrates, the enzymes displayed optimum temperatures of 50 degrees C, optimum pHs of 6.5 in each case, K(m) values for UDP-GlcNAc to be 5.8 (Hep3B) and 4.5 mM (HepG2) and K(m) values for GlcN,GlcN-biant-PA (mM) to be 1.28 (Hep3B) and 2.4 (HepG2). This indicates that values of Hep3B GlcNAc-transferase-V were distinguishable with HepG2 enzyme. Furthermore, Hep3B enzyme in membrane fraction showed about 1.5-fold higher specific activity (1.423 pmol/(h mg) than that (1.066 pmol/(h mg)) of HepG2. Normal hepatocytes are characterized by very low level of GlcNAc-transferase-V activity whereas hepatoma cells contained high activities. Treatment of hepatoma cells with retinoic acid and 1alpha,2,5-dihydroxyvitamin D(3) (Vit-D(3)) resulted in an increase in GlcNAc-transferase-V activity, while treatment with dimethyl sulfoxide and cytosine-arabinoside resulted in decrease in the enzyme activity. Although retinoic acid (RA) treated cells shows a changed GlcNAc-transferase-V mRNA expression, expression of marker proteins such as alpha-fetoprotein and albumin was not changed. This is the first demonstration of GlcNAc-transferase-V activity in RA and Vit-D(3)-treated hepatoma cell lines.

Transcriptional regulation of human beta-galactoside alpha2,6-sialyltransferase (hST6Gal I) gene in colon adenocarcinoma cell line

Previous studies have shown that hST6Gal I mRNA is overexpressed in colorectal cancer tissues compared with non-malignant or benign tissue. Moreover, Form 1 (hepatic form) mRNA isoform had a marked tendency to accumulate in colon cancer [Int. J. Cancer 88 (2000) 58-65]. These findings suggest that the transcriptional regulation of Form 1 is altered during malignant transformation. We report here transcriptional regulation of the hST6Gal I gene in colon adenocarcinoma cell lines. We characterized P1 promoter region, which regulates Form 1 mRNA expression, using luciferase assays. The result indicates that the nt-156 to -1 region is important for transcriptional activity of hST6Gal I gene in colon adenocarcinoma cell lines. The nt-156 to -1 region contains HNF1 recognition element. Mutation of the HNF1 site reduced luciferase activity by about 80% compared with the wild-type construct, suggesting that HNF1 site is involved in the transcription of Form 1 mRNA in colon cancer cells.