Expression of human lymphocyte IgE receptor (Fc epsilon RII/CD23). Identification of the Fc epsilon RIIa promoter and its functional analysis in B lymphocytes.
Two species, Fc epsilon RIIa and Fc epsilon RIIb, of the human low-affinity receptor for IgE (Fc epsilon RII/CD23) have recently been described. They differ by only six amino acids in the cytoplasmic N-terminus and are generated by different cell-specific transcriptional start sites that lead to distinct 5'-leader sequences in the corresponding mRNA. In this study, we present the analysis of the promoter which is regulating the expression of the B cell-specific Fc epsilon RIIa. Our data show that this promoter is flanked by several long repetitive elements that are influencing transcription in the Burkitt lymphoma B cell line Jijoye. Serial deletions of the 5'-flanking region of the promoter revealed two major regulatory segments that have either inhibitory or enhancing effects on transcription. In addition, IL-4 caused a two- to four-fold up-regulation of the Fc epsilon RIIa promoter activity and the DNA element responsible was mapped within the first 250 bp of the 5'-flanking region. These results were confirmed by transferring the DNA segment containing the putative IL-4 responsive element to a heterologous thymidine kinase promoter. It was concluded that IL-4 augments the Fc epsilon RIIa expression by transcriptional regulation.
Suter
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Department of Biotechnology, Ciba-Geigy Ltd., Basel, Switzerland.
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Hofstetter
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D000944:Antigens, Differentiation, B-Lymphocyte / Q000235:genetics*; D001402:B-Lymphocytes / Q000502:physiology*; D001483:Base Sequence; D002051:Burkitt Lymphoma; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D015847:Interleukin-4 / Q000494:pharmacology; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011961:Receptors, Fc / Q000235:genetics*; D017455:Receptors, IgE; D012045:Regulatory Sequences, Nucleic Acid; D014407:Tumor Cells, Cultured
D000944:Antigens, Differentiation, B-Lymphocyte; D011961:Receptors, Fc; D017455:Receptors, IgE; D015847:Interleukin-4