Nuclear factor of activated T cells contributes to the function of the CD28 response region of the granulocyte macrophage-colony stimulating factor promoter.
The granulocyte macrophage colony stimulating factor (GM-CSF) promoter contains a 10 bp element known as CK-1 or CD28RE that specifically responds to the co-stimulatory signal delivered to T cells via the CD28 surface receptor. This element is a variant NFkappaB site that does not function alone but requires an adjacent promoter region that includes a classical NFkappaB element, an Sp-1 site and a putative activator protein-1 (AP-1)-like binding site. The entire region is referred to as the CD28 response region (CD28RR). The GM-CSF CK-1 element has been shown to bind NFkappaB proteins, in particular c-Rel, whose binding and function is dependent on the architectural transcription factor HMGI(Y). It has been previously suggested that the nuclear factor of activated T cells (NFAT) family of proteins also plays a role in the activity of this region. We show here that recombinant NFATp but not AP-1 can bind to the GM-CSF CD28RR. NFATp present in activated Jurkat T cell extracts can also interact with the CD28RR. The binding of NFATp and Rel proteins requires the same core CK-1 sequences, and appears to be mutually exclusive. We investigated the functional significance of NFATp binding to CK-1 by overexpressing the protein in Jurkat T cells and found that NFATp cannot activate the CD28RR alone but can cooperate with signals generated by phorbol 12-myristate 13-acetate/calcium ionophore. The CD28RR is therefore a complex region that can bind and respond to a combination of transcription factors and signals.
Shang
C
C
Division of Human Immunology, Hanson Centre for Cancer Research, Institute of Medical and Veterinary Science, Adelaide, South Australia 5001, Australia.
Attema
J
J
Cakouros
D
D
Cockerill
P N
PN
Shannon
M F
MF
D001665:Binding Sites; D018106:CD28 Antigens / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000502:physiology*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics*; D025741:HMGA1a Protein; D006609:High Mobility Group Proteins / Q000378:metabolism; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics; D019169:Jurkat Cells; D016328:NF-kappa B / Q000378:metabolism; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D011401:Promoter Regions, Genetic; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*
D018106:CD28 Antigens; D004268:DNA-Binding Proteins; D006609:High Mobility Group Proteins; D007376:Interleukin-2; D016328:NF-kappa B; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D025741:HMGA1a Protein; D016178:Granulocyte-Macrophage Colony-Stimulating Factor