A complex composed of USF1 and USF2 activates the human FcεRI α chain expression via a CAGCTG element in the first intron

et al. 2003

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We found a novel polymorphism, −66T/C, in the promoter region of human FcεRIα, the specific component of the high affinity receptor for IgE (FcεRI), which is essential for the cell surface expression of FcεRI and the binding of IgE Ab. When the effect of the single nucleotide replacement on the promoter function was analyzed, the transcription activity of the T allele promoter was found to be higher than that of the C allele promoter, and was markedly up-regulated by the overexpression of GATA-1 when compared with the C allele promoter. This is probably because the promoter with T at −66 has an additional GATA-1-binding motif in the region, which may assure higher affinity of the transcription factor to the promoter. In accordance with this, EMSA actually indicated that GATA-1 bound to the T allele probe (−80/−59) with the affinity higher than that to the C allele probe. Statistical analysis suggested that a significant portion of nonallergic individuals has heterozygous −66T/C genotype, while most of allergic individuals have homozygous −66T/T genotype in Japanese population. Our findings for the first time demonstrate the presence of FcεRIα polymorphism related to the allergic diseases.

Section: Polymorphism In Fc⑀ri ␣-Chain Gene Regulatory Regionmentioning

confidence: 82%

A Novel −66T/C Polymorphism in FcεRI α-Chain Promoter Affecting the Transcription Activity: Possible Relationship to Allergic Diseases

Hasegawa

Nishiyama²,

et al. 2003

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“…Nuclear extracts and double-stranded oligonucleotide probes were prepared as described previously (18,19). Abs against YY1 and USF1 were purchased from Santa Cruz Biotechnology (Santa Cruz, CA).…”

Section: Emsamentioning

confidence: 99%

Polymorphisms in the FcεRIβ Promoter Region Affecting Transcription Activity: A Possible Promoter-Dependent Mechanism for Association between FcεRIβ and Atopy

Nishiyama¹,

Akizawa²,

et al. 2004

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The β subunit of the high-affinity IgE receptor (FcεRI) plays an important role in IgE-mediated allergic reactions as an amplifier for cell surface expression and signal transduction of FcεRI. FcεRIβ is presumed to be one of the genes linked with atopic diseases. However, the validity of the associations previously found between single nucleotide polymorphisms (SNPs) in FcεRIβ and atopic diseases is questionable. In the present study, we found correlation between the SNP of FcεRIβ at +6960A/G, resulting in a Glu237Gly amino acid substitution, and the cell surface expression level of FcεRI on blood basophils, although it has been shown that the Glu237Gly mutation itself does not affect the surface expression or function of FcεRI. We additionally found four SNPs in the promoter region of FcεRIβ, among which −426T/C and −654C/T were tightly linked with +6960A/G. Reporter plasmids carrying the −426C and −654T promoter displayed higher transcriptional activity than those carrying the −426T and −654C promoter. We found that transcription factor YY1 preferentially bound and transactivated the −654T promoter. Furthermore, expression of FcεRI β-chain mRNA in basophils from individuals who have the minor heterozygous genotype was significantly higher than that of the major homozygous genotype. These results suggest that the SNPs in the FcεRIβ promoter are causally linked with atopy via regulation of FcεRI expression.

“…Total amount of the plasmid used for the transfection was adjusted to 12 g by the addition of the appropriate amount of the empty plasmid pCR3.1-self (8,9), because the transfection efficiency is affected by the amount of plasmid DNA used. The cells harvested after a 24-h cultivation were lysed by PicaGene Cell Culture Lysis Reagent Luc (Toyo Ink), and the luciferase activity was measured by a PicaGene Luminescence kit (Toyo Ink).…”

Section: Transfection and Luciferase Assaymentioning

confidence: 99%

“…Nuclear extract of PT18 cells was prepared as described previously (7,9). EMSA was performed under the conditions almost the same as described previously (7); 10 g instead of 4 g of nuclear extract was used in this study.…”

Section: Emsamentioning

confidence: 99%

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Regulation of Human FcεRI α-Chain Gene Expression by Multiple Transcription Factors

Hasegawa²,

et al. 2002

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Transcriptional regulation of the gene-encoding human FcεRI α-chain was analyzed in detail. EMSA revealed that either YY1 or PU.1 bound to the region close to that recognized by Elf-1. The α-chain promoter activity was up-regulated ∼2-fold by exogenously expressed YY1 or PU.1 and ∼7-fold by GATA-1, respectively, in KU812 cells. In contrast, coexpression of GATA-1 with either of PU.1 or YY1 dramatically activated the promoter ∼41- or ∼27-fold, respectively. Especially synergic activation by GATA-1 and PU.1 was surprising, because these transcription factors are known to inhibit the respective transactivating activities of each other. These up-regulating effects of PU.1 and YY1 with GATA-1 were inhibited by overexpression of Elf-1, indicating that Elf-1 serves as a repressor for the α-chain gene expression. Transcriptional regulation of the α-chain gene through four transcriptional factors is discussed.