A 361 base pair region of the rat FSH- β promoter contains multiple progesterone receptor-binding sequences and confers progesterone responsiveness

The rat is frequently used as a model to study the role of progesterone (P) in regulating FSH secretion and synthesis. The ability of P to modulate rat FSH- β mRNA levels suggests the presence of a functional hormone response element. We have found three PRE-like sequences upstream of the transcription start site in the rat FSH- β gene. These sequences are herein referred to as PRE-like sequence #1, #2 and #3 with #1 being most distal from the start site. The current studies determined whether these PRE-like sequences bound P receptor (PR) and were functional in regulating the induction of expression by P. Electrophoretic mobility shift assays (EMSA) demonstrated that a single 289 base pair (bp) DNA fragment encompassing all three PRE-like sequences specifically bound PR. Further, PR bound with high affinity to double-stranded oligonucleotides representing individual PRE-like sequences #1, #2 and, with lower affinity to a double-stranded oligonucleotide representing PRE-like sequence, #3. We have cloned a 361 bp sequence from the promoter region of the rat FSH- β gene encompassing all three PRE-like sequences into a luciferase reporter vector (pGL3-promoter) yielding pFSH β361-luc+ which when transiently transfected into primary rat pituitary cell cultures, conferred P-responsiveness to a heterologous promoter. P-responsiveness was dependent upon the presence of PR and was blocked by the PR antagonist RU-486. These data strongly suggest the presence of functional PRE’s in the rat FSH- β gene promoter.