Analysis of the promoter of the luteinizing hormone/human chorionic gonadotropin receptor gene in neuroendocrine cells

We investigated the molecular basis of luteinizing hormone (LH)/human chorionic gonadotropin (hCG) receptor gene transcription in immortalized alpha T3 gonadotropes, hypothalamic GT1-7 and hippocampal HN33p neurons. Nuclear run-on transcription, as well as transfection assays with fusion constructs of luciferase and the 5'-flanking region of LH/hCG receptor gene, revealed that GT1-7 neurons transcribe more than the alpha T3 or HN33p cells. Transient transfection of truncated reporter gene constructs and gel mobility shift assays revealed that while all neuroendocrine cells use the same promoter, they contain different levels of promoter binding proteins. Higher levels of these proteins may explain increased transcription of the LH/hCG receptor gene in GT1-7 neurons compared with alpha T3 and HN33p cells.