Transcriptional regulation of CHI3L1, a marker gene for late stages of macrophage differentiation.
The protein product of the CHI3L1 gene, human cartilage 39-kDa glycoprotein (HC-gp39), is a tissue-restricted, chitin-binding lectin and member of glycosyl hydrolase family 18. In contrast to many other monocyte/macrophage markers, its expression is absent in monocytes and strongly induced during late stages of human macrophage differentiation. To gain insights into the molecular mechanisms underlying its cell type-restricted and maturation-associated expression in macrophages, we initiated a detailed study of the proximal HC-gp39 promoter. Deletion analysis of reporter constructs in macrophage-like THP-1 cells localized a region directing high levels of macrophage-specific reporter gene expression to approximately 300 bp adjacent to the major transcriptional start site. The promoter sequence contained consensus binding sites for several known factors, and specific binding of nuclear PU.1, Sp1, Sp3, USF, AML-1, and C/EBP proteins was detectable in gel shift assays. In vivo footprinting assays with dimethyl sulfate demonstrate that the protection of corresponding sequences was enhanced in macrophages compared with monocytes. Mutational analysis of transcription factor binding sites indicated a predominant role for a single Sp1 binding site in regulating HC-gp39 promoter activity. In addition, gel shift assays using nuclear extracts of monocytes and macrophages demonstrated that the binding of nuclear Sp1, but not Sp3, markedly increases during macrophage differentiation. Our results further highlight the important role of Sp1 in macrophage gene regulation.
Rehli
Michael
M
Department of Hematology and Oncology, University of Regensburg, 93042 Regensburg, Germany. michael.rehli@klinik.uni-regensburg.de
Niller
Hans-Helmut
HH
Ammon
Christoph
C
Langmann
Sabine
S
Schwarzfischer
Lucia
L
Andreesen
Reinhard
R
Krause
Stefan W
SW
D054392:Adipokines; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002454:Cell Differentiation / Q000235:genetics*; D002460:Cell Line; D002467:Cell Nucleus / Q000737:chemistry; D000071451:Chitinase-3-Like Protein 1; D016384:Consensus Sequence; D004247:DNA / Q000378:metabolism; D018983:DNA Footprinting; D004330:Drosophila / Q000235:genetics; D024202:Electrophoretic Mobility Shift Assay; D017353:Gene Deletion; D015870:Gene Expression; D005786:Gene Expression Regulation / Q000187:drug effects; D006023:Glycoproteins / Q000235:genetics*; D006801:Humans; D037102:Lectins; D008264:Macrophages / Q000166:cytology*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D011401:Promoter Regions, Genetic / Q000235:genetics; D016329:Sp1 Transcription Factor / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection
D054392:Adipokines; C084533:CHI3L1 protein, human; D000071451:Chitinase-3-Like Protein 1; D006023:Glycoproteins; D037102:Lectins; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; D004247:DNA; D013755:Tetradecanoylphorbol Acetate