Transcriptional regulation of pituitary gonadotrophin subunit genes

The gonadotrophic hormones, LH and FSH, are synthesized in and secreted fro m gonadotroph cells in the anterior pituitary and comprise a common alpha-s ubunit and a hormone-specific beta-subunit. Gonadotrophic gene expression i s activated during embryogenesis, independent of GnRH stimulation and incre ases as GnRH output increases, reaching adult levels at puberty. The transc riptional regulation of pituitary gonadotrophin subunit gene expression is regulated by two types of transcription factor: those that restrict and dir ect gene expression to gonadotrophs and those that modulate GnRH-regulated gene expression. Synergism between these two types of factor ensures gonado troph-specific GnRH-regulated gene expression. It is not known whether thes e two types of transcription factor are mutually exclusive or whether they have overlapping functions. GnRH-regulated gonadotrophin subunit gene expre ssion is modulated by transcription factors controlled by a complex interac tion of GnRH, steroids and gonadal peptides, all of which bind to receptors that activate disparate intracellular signalling pathways. It remains to b e established how these signalling pathways interact to transduce specific transcriptional activation of common alpha-subunit and LH and FSH beta-subu nit gene expression.