Analysis of the CCR3 promoter reveals a regulatory region in exon 1 that binds GATA-1.
BACKGROUND
CC Chemokine Receptor 3 (CCR3), the major chemokine receptor expressed on eosinophils, binds promiscuously to several ligands including eotaxins 1, 2, and 3. Even though the only cells that consistently accumulate following eotaxin administration in vivo are myeloid cells (primarily eosinophils), other cell types have recently been shown to express CCR3. It is therefore important to elucidate the molecular mechanisms regulating receptor expression.


RESULTS
In order to define regions responsible for CCR3 transcription, a DNAse hypersensitive site was identified in the vicinity of exon 1. Coupled with our previous data implicating exon 1 in CCR3 transcription, we hypothesized that transcription factors bind to exon-1. Electrophoretic mobility shift analysis revealed that nuclear proteins in eosinophilic cells bound to exon 1. Furthermore, antibody interference and mutation studies demonstrated GATA-1 binding to exon 1. In order to test the 1.6-kb CCR3 promoter element (that includes exon 1) for in vivo function, this region was used to generate transgenic mice that expressed a reporter protein. Strong transgene expression was achieved, with the pattern of expression suggesting a broad acting promoter.


CONCLUSIONS
The transcription factor GATA-1 binds to CCR3 exon 1. The 1.6-kb CCR3 promoter element, that includes exon 1, is a strong promoter in vivo.
Zimmermann
Nives
N
Division of Allergy and Immunology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA. Nives.Zimmermann@cchmc.org
Colyer
Jessica L
JL
Koch
Laura E
LE
Rothenberg
Marc E
ME
D000818:Animals; D003850:Deoxyribonuclease I / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D004804:Eosinophils / Q000378:metabolism; D005091:Exons / Q000235:genetics*; D050982:GATA1 Transcription Factor / Q000378:metabolism*; D017930:Genes, Reporter; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D009928:Organ Specificity; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding; D054397:Receptors, CCR3; D019707:Receptors, Chemokine / Q000378:metabolism*; D014158:Transcription, Genetic; D019076:Transgenes
C515350:CCR3 protein, human; C515351:Ccr3 protein, mouse; D050982:GATA1 Transcription Factor; D054397:Receptors, CCR3; D019707:Receptors, Chemokine; D003850:Deoxyribonuclease I