Identification of domains mediating transcription activation, repression, and inhibition in the paired-related homeobox protein, Prx2 (S8).
Despite the growing information concerning the developmental importance of the Prx2 protein, the structural determinants of Prx2 function are poorly understood. To gain insight into the transcription regulatory regions of the Prx2 protein, we generated a series of truncation mutants. Both the Prx2 response element (PRE) and a portion of the tenascin promoter, a downstream target of Prx2, were used as reporters in transient transfection assays. This analysis showed that a conserved domain (PRX), found in both Prx1 and Prx2, activated transcription in NIH 3T3 cells. This PRX domain, as well as other functional regions of Prx2, demonstrated both cell-specific and promoter-dependent transcriptional regulation. A second important region, the OAR (aristaless) domain, which is conserved among 35 Paired-type homeodomain proteins, was observed to inhibit transcription. Deletion of this element resulted in a 20-fold increase of transcription from the tenascin reporter in NIH 3T3 cells but not in C2C12 cells. The OAR domain did not function as a repressor in chimeric fusions with the Gal4 DNA binding domain in either cell type, characterizing it as an inhibitor instead of a repressor. These results give insight into the function of the Prx2 transcription factor while establishing the framework for comparison with the two isoforms of Prx1.
University of South Carolina, Department of Cell Biology and Anatomy, Charleston, South Carolina, USA.
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Norris
M J
MJ
Kern
D016475:3T3 Cells; D020816:Amino Acid Motifs / Q000235:genetics; D000818:Animals; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism; D029721:Drosophila Proteins; D005136:Eye Proteins; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D019476:Insect Proteins / Q000235:genetics / Q000502:physiology; D051379:Mice; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000502:physiology; D010446:Peptide Fragments / Q000235:genetics / Q000502:physiology; D011401:Promoter Regions, Genetic; D011485:Protein Binding / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D012097:Repressor Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D019063:Tenascin / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014162:Transfection
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D005136:Eye Proteins; D018398:Homeodomain Proteins; D019476:Insect Proteins; D009419:Nerve Tissue Proteins; C088624:Otp protein, mouse; D010446:Peptide Fragments; C115469:Prrx2 protein, mouse; C105441:Rax protein, mouse; D012097:Repressor Proteins; C111251:Rx protein, vertebrate; D019063:Tenascin; D015534:Trans-Activators; D014157:Transcription Factors; C079410:al protein, Drosophila; C490260:otp protein, Drosophila