Elf-1 and Stat5 bind to a critical element in a new enhancer of the human interleukin-2 receptor alpha gene.
The interleukin 2 receptor alpha-chain (IL-2R alpha) gene is a key regulator of lymphocyte proliferation. IL-2R alpha is rapidly and potently induced in T cells in response to mitogenic stimuli. Interleukin 2 (IL-2) stimulates IL-2R alpha. transcription, thereby amplifying expression of its own high-affinity receptor. IL-2R alpha transcription is at least in part controlled by two positive regulatory regions, PRRI and PRRII. PRRI is an inducible proximal enhancer, located between nucleotides -276 and -244, which contains NF-kappaB and SRE/CArG motifs. PRRII is a T-cell-specific enhancer, located between nucleotides -137 and -64, which binds the T-cell-specific Ets protein Elf-1 and HMG-I(Y) proteins. However, none of these proximal regions account for the induction of IL-2R alpha transcription by IL-2. To find new regulatory regions of the IL-2R alpha gene, 8.5 kb of the 5' end noncoding sequence of the IL-2R alpha gene have been sequenced. We identified an 86-nucleotide fragment that is 90% identical to the recently characterized murine IL-2-responsive element (mIL-2rE). This putative human IL-2rE, designated PRRIII, confers IL-2 responsiveness on a heterologous promoter. PRRIII contains a Stat protein binding site that overlaps with an EBS motif (GASd/EBSd). These are essential for IL-2 inducibility of PRRIII/CAT reporter constructs. IL-2 induced the binding of Stat5a and b proteins to the human GASd element. To confirm the physiological relevance of these findings, we carried out in vivo footprinting experiments which showed that stimulation of IL-2R alpha expression correlated with occupancy of the GASd element. Our data demonstrate a major role of the GASd/EBSd element in IL-2R alpha regulation and suggest that the T-cell-specific Elf-1 factor can serve as a transcriptional repressor.
Lécine
P
P
INSERM U119, Marseille, France.
Algarté
M
M
Rameil
P
P
Beadling
C
C
Bucher
P
P
Nabholz
M
M
Imbert
J
J
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics*; D004742:Enhancer Elements, Genetic / Q000235:genetics*; D036383:Ephrin-A2; D005786:Gene Expression Regulation; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism*; D051379:Mice; D008894:Milk Proteins; D008969:Molecular Sequence Data; D011506:Proteins / Q000235:genetics*; D015375:Receptors, Interleukin-2 / Q000235:genetics* / Q000378:metabolism; D050799:STAT5 Transcription Factor; D013601:T-Lymphocytes / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics*; D025521:Tumor Suppressor Proteins
D004268:DNA-Binding Proteins; D036383:Ephrin-A2; D007376:Interleukin-2; D008894:Milk Proteins; D011506:Proteins; D015375:Receptors, Interleukin-2; D050799:STAT5 Transcription Factor; C494092:STAT5A protein, human; C494093:Stat5a protein, mouse; D015534:Trans-Activators; D025521:Tumor Suppressor Proteins