Characterization of a promoter region supporting transcription of a novel human β-galactoside α-2,6-sialyltransferase transcript in HepG2 cells

Aas‐Eng, Dordi Anne; Åsheim, H.-C.; Deggerdal, A.; Smeland, Erlend B.; Funderud, Steinar

doi:10.1016/0167-4781(94)00250-7

Cited by 37 publications

(12 citation statements)

References 32 publications

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“…Although enhanced steady state transcription is the most obvious explanation for the accumulation of ST6Gal I mRNA in the presence of K‐Ras S12 or H‐Ras V12 it cannot be excluded that increased mRNA stability may also contribute to the high levels of ST6Gal I mRNA in Ras transformed cells. However, previous work has shown that quantitative changes of a particular class of ST6Gal I 5′UT transcripts (including P3) are primarily the result of transcriptional activity at the matching promoter [45–47].…”

Section: Discussionmentioning

confidence: 99%

Ras oncogene induces β‐galactoside α2,6‐sialyltransferase (ST6Gal I) via a RalGEF‐mediated signal to its housekeeping promoter

Dalziel¹,

Dall’Olio²,

Mungul³

et al. 2004

European Journal of Biochemistry

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Several oncogenic proteins are known to influence cellular glycosylation. In particular, transfection of codon 12 point mutated H‐Ras increases CMP‐Neu5Ac: Galβ1,4GlcNAc α2,6‐sialyltransferase I (ST6Gal I) activity in rodent fibroblasts. Given that Ras mediates its effects through at least three secondary effector pathways (Raf, RalGEFs and PI3K) and that transcriptional control of mouse ST6Gal I is achieved by the selective use of multiple promoters, we attempted to identify which of these parameters are involved in linking the Ras signal to ST6Gal I gene transcription in mouse fibroblasts. Transformation by human K‐Ras or H‐Ras (S12 and V12 point mutations, respectively) results in a 10‐fold increase in ST6Gal I mRNA, but no alteration in the expression of related sialyltransferases. Using an inducible H‐RasV12 expression system, a direct causal link between activated H‐Ras expression and elevated ST6Gal I mRNA was demonstrated. The accumulation of the ST6Gal I transcript in response to activated Ras was accompanied by an increase of α2,6‐sialyltransferase activity and of Neu5Acα2,6Gal at the cell surface. Results obtained with H‐RasV12 partial loss of function mutants H‐RasV12S35 (Raf signal only), H‐RasV12C40 (PI3‐kinase signal only) and H‐RasV12G37 (RalGEFs signal only) suggest that the H‐Ras induction of the mouse ST6Gal I gene (Siat1) transcription is primarily routed through RalGEFs. 5′‐Rapid amplification of cDNA ends analysis demonstrated that the increase in ST6Gal I mRNA upon H‐RasV12 or K‐RasS12 transfection is mediated by the Siat1 housekeeping promoter P3‐associated 5′ untranslated exons.

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Section: Discussionmentioning

confidence: 99%

Ras oncogene induces β‐galactoside α2,6‐sialyltransferase (ST6Gal I) via a RalGEF‐mediated signal to its housekeeping promoter

Dalziel¹,

Dall’Olio²,

Mungul³

et al. 2004

European Journal of Biochemistry

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“…The expression of these enzymes is mostly regulated at the transcriptional level through the usage of alternative untranslated 5′ exons under the control of tissue-specific promoters. In particular, it is well-established that ST6GAL1 expression is regulated by three major promoters leading to the expression of an ubiquitous transcript [19], a mature B lymphocytes-specific transcript [20] and a liver-specific mRNA [21]. In contrast, nothing is known about ST6GAL2 transcriptional regulation, but a specific control seems to occur in brain, especially during embryonic development.…”

Section: Introductionmentioning

confidence: 95%

Transcriptional regulation of the human ST6GAL2 gene in cerebral cortex and neuronal cells

et al. 2009

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The second human beta-galactoside alpha-2,6-sialyltransferase (hST6Gal II) differs from hST6Gal I, the first member of ST6Gal family, in substrate specificity and tissue expression pattern. While ST6GAL1 gene is expressed in almost all human tissues, ST6GAL2 shows a restricted tissue-specific pattern of expression, mostly expressed in embryonic and adult brain. In order to understand the mechanisms involved in the transcriptional regulation of ST6GAL2, we first characterized the transcription start sites (TSS) in SH-SY5Y neuroblastoma cells. 5' RACE experiments revealed multiple TSS located on three first alternative 5' exons, termed EX, EY and EZ, which are unusually close on the genomic sequence and are all located more than 42 kbp upstream of the first common coding exon. Using Taqman duplex Q-PCR, we showed that the ST6GAL2 transcripts initiated by EX or EY are mainly expressed in both brain-related cell lines and human cerebral cortex, testifying for the use of a similar transcriptional regulation in vivo. Furthermore, we also showed for the first time hST6Gal II protein expression in the different lobes of the human cortex. Luciferase reporter assays allowed us to define two sequences upstream EX and EY with a high and moderate promoter activity, respectively. Bioinformatics analysis and site-directed mutagenesis showed that NF-kappaB and NRSF are likely to act as transcriptional repressors, whereas neuronal-related development factors Sox5, Puralpha and Olf1, are likely to act as transcriptional activators of ST6GAL2. This suggests that ST6GAL2 transcription could be potentially activated for specific neuronal functions.

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“…The ST6Gal I gene is expressed in most tissues, while the ST6Gal II gene is expressed only in small intestine, colon and fetal brain [48]. In humans, there are at least three isoforms of the ST6Gal I transcript; form 1 is expressed in liver, form 2 in B cell lines, and form 3 in many other tissues [28][29][30][31][32]. RT-PCR analysis showed that only form 3 is expressed in TIG-3 cells and that the expression level decreases in PDL 77 cells when compared with PDL 23 cells.…”

Section: Discussionmentioning

confidence: 99%

“…At least three different promoters have been described to control the tissuespecific expression of the transcripts. The form 1 is expressed predominantly in liver, form 2 in B cell lines, and form 3 in many other tissues [29][30][31][32]. In order to investigate which isoform is expressed in TIG-3 cells, RT-PCR analysis was performed in PDLs 23 and 77 cells using three different sets of primers (pI and pII, pX and pII, and pY and pII) specific to the individual isoforms ( Fig.…”

Section: Isoforms Of the St6gal I Transcript In Tig-3 Cellsmentioning

confidence: 99%

Preferential reduction of the α-2-6-sialylation from cell surface N-glycans of human diploid fibroblastic cells by in vitro aging

et al. 2006

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Human diploid fibroblastic cell line, TIG-3, has a finite life span of about 80 population doubling levels (PDL), and is used for in vitro aging studies. Young cells (PDL 23) grew to higher cell densities at a higher growth rate than aged cells (PDL 77). When the electrophoretic mobility of cells was determined, the negative surface charge of the aged cells decreased significantly when compared to that of young cells. Lectin blot analysis of membrane glycoproteins showed that the alpha-2-6-sialylation but not the alpha-2-3-sialylation of N-glycans decreases markedly in the aged cells when compared to the young cells. In support of this observation, the cDNA microarray assay and reverse transcription-polymerase chain reaction (RT-PCR) analysis showed that the gene expression of the alpha-2,6-sialyltransferase I (ST6Gal I), which transfers sialic acid to galactose residues of N-glycans, decreases in the aged cells. These results indicate that the concordant decrease of the alpha-2,6-sialylation of N-glycans with the ST6Gal I gene expression is induced in TIG-3 cells by in vitro aging.

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Characterization of a promoter region supporting transcription of a novel human β-galactoside α-2,6-sialyltransferase transcript in HepG2 cells

Cited by 37 publications

References 32 publications

Ras oncogene induces β‐galactoside α2,6‐sialyltransferase (ST6Gal I) via a RalGEF‐mediated signal to its housekeeping promoter

Ras oncogene induces β‐galactoside α2,6‐sialyltransferase (ST6Gal I) via a RalGEF‐mediated signal to its housekeeping promoter

Transcriptional regulation of the human ST6GAL2 gene in cerebral cortex and neuronal cells

Preferential reduction of the α-2-6-sialylation from cell surface N-glycans of human diploid fibroblastic cells by in vitro aging

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