Germ cell nuclear factor is a response element-specific repressor of transcription.
We have shown that the orphan receptor Germ Cell Nuclear Factor (GCNF) binds to a direct repeat of the sequence AGGTCA with zero base pair spacing (DR0). Here, we further characterize the binding characteristics of GCNF. We demonstrate that GCNF binds specifically to DR0s as a homodimer, and does not bind with high affinity to DR1-DR6 sequences. GCNF is the first nuclear receptor shown to bind specifically to DR0s. The wild type GCNF is unable to transactivate the reporter plasmid DR0(2)tkCAT. Lacking a ligand to activate GCNF, we fused the activation domain from the viral protein VP16 to GCNF, and observed activation of DR0(2)tkCAT. This activation is specifc to DR0s, and is not observed when that sequence is replaced by DR1-DR6 sequences. In addition GCNF does not transactivate through an SF-1 response element. At increasing concentrations, wild type GCNF is able to repress basal transcription. Repression is again specific to DR0s. The preference of GCNF for the DR0 sequence both in vitro and in transfections suggests that GCNF defines a novel nuclear receptor signaling pathway.
Cooney
A J
AJ
Department of Cell Biology, Baylor College of Medicine, Houston, Texas, 77030, USA. acooney@bcm.tmc.edu
Hummelke
G C
GC
Herman
T
T
Chen
F
F
Jackson
K J
KJ
D004268:DNA-Binding Proteins / Q000502:physiology*; D019281:Dimerization; D017930:Genes, Reporter / Q000235:genetics; D008968:Molecular Conformation; D057136:Nuclear Receptor Subfamily 6, Group A, Member 1; D018160:Receptors, Cytoplasmic and Nuclear / Q000502:physiology*; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D012097:Repressor Proteins / Q000494:pharmacology*; D015398:Signal Transduction / Q000502:physiology; D014158:Transcription, Genetic / Q000235:genetics*; D015533:Transcriptional Activation / Q000235:genetics; D014162:Transfection / Q000235:genetics; D014407:Tumor Cells, Cultured; D014764:Viral Proteins / Q000235:genetics
D004268:DNA-Binding Proteins; D057136:Nuclear Receptor Subfamily 6, Group A, Member 1; D018160:Receptors, Cytoplasmic and Nuclear; D012097:Repressor Proteins; D014764:Viral Proteins