Identification and characterization of a critical CP2-binding element in the human interleukin-4 promoter.
Expression of cytokine genes in T cells is thought to result from a complex network of antigen- and mitogen-activated transcriptional regulators. CP2, a factor homologous to Drosophila Elf-1 and previously found to be a critical regulator of several viral and cellular genes in response to developmental signals, is rapidly activated in T helper (Th) cells in response to mitogenic stimulation. Here we show that overexpression of CP2 enhances interleukin (IL)-4 promoter-driven chloramphenicol acetyltransferase expression, while repressing IL-2 promoter activity, in transiently transfected Jurkat cells. A CP2-protected element, partially overlapping the nuclear factor of activated T cell-binding P2 sequence, was required for IL-4 promoter activation in CP2-overexpressing Jurkat cells. This CP2-response element is the site of a cooperative interaction between CP2 and an inducible heteromeric co-factor(s). Mutation of conserved nucleotide contacts within the CP2-response element prevented CP2 binding and significantly reduced constitutive and induced IL-4 promoter activity. Expression of a CP2 mutant lacking the Elf-1-homology region of the DNA-binding domain inhibited IL-4 promoter activity in a dominant negative fashion in transiently transfected Jurkat cells. Moreover, overexpressed CP2 markedly enhanced, while its dominant negative mutant consistently suppressed, expression of the endogenous IL-4 gene in the murine Th2 cell line D10. Taken together, these findings point to CP2 as a critical IL-4 transactivator in Th cells.
Casolaro
V
V
Department of Medicine, The Johns Hopkins School of Medicine, Baltimore, Maryland 21224, USA. casolaro@mail.jhmi.edu
Keane-Myers
A M
AM
Swendeman
S L
SL
Steindler
C
C
Zhong
F
F
Sheffery
M
M
Georas
S N
SN
Ono
S J
SJ
D001483:Base Sequence; D016384:Consensus Sequence; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics; D015847:Interleukin-4 / Q000235:genetics*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D016601:RNA-Binding Proteins; D013601:T-Lymphocytes / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*
D004268:DNA-Binding Proteins; D007376:Interleukin-2; D016601:RNA-Binding Proteins; D014157:Transcription Factors; D015847:Interleukin-4; D004247:DNA