Nuclear factor of activated T cells (NFAT) as a molecular target for 1alpha,25-dihydroxyvitamin D3-mediated effects.
The molecular basis of the immunomodulatory properties of 1alpha,25-dihydroxyvitamin D3 (1alpha,25(OH)2D3) remains elusive. We demonstrate here that 1alpha,25(OH)2D3-mediated suppressive effects on the inducible expression of cytokine genes in human T cells may, in part, be due to diminished activity of the transcription factor NFAT. The vitamin D3 receptor (VDR) and its heterodimeric partner retinoid X receptor alpha (RXR alpha) specifically bound to the distal NFAT site in the human IL-2 promoter, and this binding was abolished by mutating unique regions in the NFAT oligonucleotide. In vitro inhibition of NFAT complex formation was noted when VDR-RXR alpha heterodimers were added to DNA binding reactions containing nuclear extracts from activated B or T cells, whereas in vitro NFkappaB complex formation was not significantly influenced. Furthermore, 1alpha,25(OH)2D3 treatment of activated T cells resulted in decreased formation of NFAT complexes detected upon incubation of nuclear extracts from these cells with 32P-labeled probe. Transient expression of both VDR and RXR alpha, but not of a single component, was capable of inhibiting expression of a NFAT-driven reporter gene in stimulated jurkat cells in a ligand-dependent manner. These results suggest that NFAT plays a crucial role in 1alpha,25(OH)2D3-mediated immunosuppressive activity.
Takeuchi
A
A
Department of Pathology, Roger Williams Medical Center, Brown University, Providence, RI 02908, USA.
Reddy
G S
GS
Kobayashi
T
T
Okano
T
T
Park
J
J
Sharma
S
S
D001483:Base Sequence; D001665:Binding Sites; D002117:Calcitriol / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000502:physiology*; D019281:Dimerization; D005786:Gene Expression Regulation; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics*; D019169:Jurkat Cells; D008213:Lymphocyte Activation; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D014066:Palatine Tonsil / Q000166:cytology; D011401:Promoter Regions, Genetic; D018167:Receptors, Calcitriol / Q000502:physiology; D018168:Receptors, Retinoic Acid / Q000502:physiology; D047488:Retinoid X Receptors; D013601:T-Lymphocytes / Q000276:immunology*; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D007376:Interleukin-2; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D018167:Receptors, Calcitriol; D018168:Receptors, Retinoic Acid; D047488:Retinoid X Receptors; D014157:Transcription Factors; D002117:Calcitriol