Disinhibiting an Inhibitor: Genetic Engineering Leads to Improvements in Recombinant Inhibin A Production

Inhibins were first postulated as hypothetical hormones in the 1930s but were not purified until the 1980s (1). This delay is emblematic of the many challenges inhibin researchers have faced over the past century. Although early progress in the field was slow, work in the 1970s lay the foundation for our current conception of inhibins as gonadally derived hormones that selectively regulate FSH synthesis and secretion by pituitary gonadotrope cells (2-4). More recent research indicates that inhibins may have pleiotropic actions, regulating extrapituitary tissues, including the ovaries and bone (1). Nonetheless, it was in the context of FSH regulation that 2 forms of inhibin, A and B, were purified from ovarian follicular fluid and shown to be heterodimers of a single [alpha]-subunit disulfide-linked to one of two [beta]-subunits (5-8).