Oral Presentation The Joint Annual Scientific Meetings of the Endocrine Society of Australia and the Society for Reproductive Biology 2017

Characterising the physiology and therapeutic potential of inhibin A and B (#28)

Monica P Goney 1 , Kelly L Walton 1 , Georgia M Goodchild 1 , Peter G Stanton 2 , Craig A Harrison 1
  1. Monash University, Clayton, VIC, Australia
  2. Hudson Institute of Medical Research, Melbourne, VIC, Australia

Characterising the physiological roles of inhibin A and B has been complicated by two major hurdles. Firstly, inhibin deficient mice develop gonadal tumours due to increased activin expression and die between 12-17 weeks of age from severe body wasting. The pathology in these mice does not reflect inhibin insufficiency, but rather activin hyperactivity. Secondly, as inhibins (α/β heterodimers) and activins (β/β homodimers) share a common β-subunit, inhibin production and purification is always hampered by activin interference. To overcome the first limitation, we are using CRISPR/Cas9 technology to introduce a single point mutation into the inhibin α-subunit of mice. We have already shown in vitro that this mutation inactivates inhibin (by silencing processing of the α-subunit) without affecting activin expression and activity. This mouse model will finally allow us to examine the physiological effects of the loss of inhibin activity. To circumvent activin interference during inhibin production, we have used in vitro mutagenesis to modify residues involved in dimerisation of the βA- and βB-subunits. These modifications dramatically limit formation and block activity of activins. Importantly, the residues introduced into the β-subunits do not affect inhibin expression or activity, as determined using an inhibin-responsive reporter assay in COV434 granulosa cells. Using this approach, we are now generating milligram quantities of inhibins that are free of contaminating activin bioactivity, allowing us for the first time to test the therapeutic potential of these gonadal hormones on bone and muscle growth.