Gfi1:green fluorescent protein knock-in mutant reveals differential expression and autoregulation of the growth factor independence 1 (Gfi1) gene during lymphocyte development.
The Gfi1 gene encodes a 55-kDa transcriptional repressor protein with important functions in T-cell development, in granulopoiesis, and in the regulation of the innate immune response. To follow expression of the Gfi1 gene during the differentiation of specific immune cells, we have generated a mouse mutant in which the Gfi1 coding region is replaced by the gene for the green fluorescent protein (GFP). We found that Gfi1 gene expression is highest in early B-cell subpopulation and differentially expressed during T-cell development with peak levels at stages where pre-TCR or positive/negative selection takes place. Gfi1 is absent in mature B-cells, whereas in peripheral T-cells Gfi1 gene expression is low but rises significantly upon T-cell receptor triggering and decreases again in T-memory cells. Constitutive expression of an lck promoter-driven Gfi1 transgene led to transcriptional silencing of the Gfi1:GFP allele in T-cells. Because Gfi1 was found to occupy genomic sites of its own promoter in thymocytes and was able to repress its own transcription in vitro we propose that transcription of the Gfi1 gene is regulated through an autoregulatory feedback loop.
Yücel
Raif
R
Institut für Zellbiologie (Tumorforschung), Universitätsklinikum Essen, Virchowstrasse 173, D-45122 Essen, Germany.
Kosan
Christian
C
Heyd
Florian
F
Möröy
Tarik
T
D000483:Alleles; D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism; D001483:Base Sequence; D015704:CD4 Antigens / Q000096:biosynthesis; D016827:CD8 Antigens / Q000096:biosynthesis; D002454:Cell Differentiation; D002455:Cell Division; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D015536:Down-Regulation; D005434:Flow Cytometry; D005557:Formaldehyde / Q000494:pharmacology; D005786:Gene Expression Regulation; D018507:Gene Expression Regulation, Developmental; D020868:Gene Silencing; D017930:Genes, Reporter; D016678:Genome; D006098:Granulocytes / Q000378:metabolism; D049452:Green Fluorescent Proteins; D007156:Immunologic Memory; D008164:Luminescent Proteins / Q000235:genetics* / Q000378:metabolism; D008214:Lymphocytes / Q000166:cytology* / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D008856:Microscopy, Fluorescence; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D011995:Recombination, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics*; D014158:Transcription, Genetic; D014162:Transfection; D019076:Transgenes; D015854:Up-Regulation
D015704:CD4 Antigens; D016827:CD8 Antigens; D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins; C079873:Gfi1 protein, mouse; D008164:Luminescent Proteins; D012333:RNA, Messenger; D011948:Receptors, Antigen, T-Cell; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; D005557:Formaldehyde; D012313:RNA