Identification of a novel OCT1 binding site that is necessary for the elaboration of pulses of rat GnRH promoter activity.
Recent evidence from our laboratory demonstrated that the OCT1 protein was necessary for GnRH gene promoter pulse activity through its interaction with a specific OCT1 binding site (OCT1BS-a, -1,774/-1,781). In light of the importance of this POU homeoprotein in pulsatile function, we focused on two other highly conserved OCT1 sites within this region, OCT1BS-b (-1,694/-1,701, previously AT-b), and OCT1BS-c (-1,569/-1,562). Mutagenesis of these sites revealed that alteration of OCT1BS-c, but not OCT1BS-b, virtually abolished gene expression pulses in GT1-7 cells. EMSAs confirmed that OCT1 can bind to both sites. Taken together, our findings demonstrate clearly that more than one Oct1 binding site is necessary for GnRH promoter pulses. Moreover, the lack of an influence observed with OCT1BS-b on pulse activity indicates that OCT1 action is not general to all OCT1 sites, but specific to certain octamer sequences in the NSE region of the GnRH promoter.
Leclerc
Gilles M
GM
Laboratory of Molecular Dynamics, Department of Cell Biology and Anatomy, Medical University of South Carolina, 173 Ashley Avenue, Charleston, 29425, USA.
Boockfor
Fredric R
FR
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D050482:Catecholamine Plasma Membrane Transport Proteins / Q000378:metabolism*; D002460:Cell Line; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation; D007987:Gonadotropin-Releasing Hormone / Q000235:genetics*; D018398:Homeodomain Proteins / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D009154:Mutation; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D051381:Rats; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology
D050482:Catecholamine Plasma Membrane Transport Proteins; D018398:Homeodomain Proteins; C493212:Slc22a1 protein, rat; D014157:Transcription Factors; D007987:Gonadotropin-Releasing Hormone