Proteins from Female Mouse Hypothalamus Associate with Progesterone Receptor Complexes in an Isoform-Specific and Ligand-Dependent Manner

Program: Abstracts - Orals, Poster Previews, and Posters
Session: SUN 203-235-Steroid Hormone Actions, Biosynthesis and Metabolism (posters)
Bench to Bedside
Sunday, April 3, 2016: 1:15 PM-3:15 PM
Exhibit/Poster Hall (BCEC)

Poster Board SUN 234
Kalpana D Acharya*1, Sabin A Nettles1, Cheryl F Lichti2, Larry Denner2 and Marc J Tetel1
1Wellesley College, Wellesley, MA, 2University of Texas Medical Branch, Galveston, TX
Progesterone receptors (PR) act throughout the body to profoundly influence a variety of processes, including development, energy homeostasis and reproduction.  In brain, PR are integral in sexual differentiation of brain, neuroprotection and cognition. PR exist as two major isoforms in mammals PR-A and PR-B, that can mediate differential responses. Multiple proteins associate with PR in a ligand-dependent manner to form functional complexes. Identifying components of these PR complexes can provide insights into the mechanisms for the differential functions of the receptor isoforms in physiology and disease. In the current study, we used affinity pull-downs and mass spectrometry to quantify proteins in PR isoform complexes from adult female mouse hypothalamus. Using GST-tagged mouse PR-A and PR-B, we identified proteins involved in a range of cellular functions that associated with PR-A only, PR-B only, or both isoforms.  Interestingly, agonist (R5020)-activated PR-B, but not PR-A, complexes contained androgen receptor (AR), providing evidence for cross-talk between these steroid receptors. PR-A and PR-B complexes showed ligand-dependent association with multiple proteins involved in cellular energy metabolism. PR-A-specific interactions were observed with proteins such as histone 4 and elongation factor 1β, mediators of transcription and translation, respectively. PR-A and PR-B complexes also associated, in a ligand-dependent manner, with proteins involved in dynamic organization of synaptic structure (e.g. tubulins β-2A and β-5) and function (e.g. synpasin-1 and synapsin-2). Select proteins identified by mass spectrometry in PR complexes were confirmed by western blot analysis. Furthermore, we are expanding these studies to include analysis by reverse phase protein array. Taken together, the present results using biologically relevant hypothalamic tissue reveal that AR and other proteins involved in a variety of cellular functions, including metabolism and synaptic function, demonstrate ligand-dependent association with PR-A and PR-B complexes.  In addition, these findings suggest mechanisms for the differential function of the PR isoforms in physiology, behavior and disease.

Nothing to Disclose: KDA, SAN, CFL, LD, MJT

*Please take note of The Endocrine Society's News Embargo Policy at https://www.endocrine.org/news-room/endo-annual-meeting/pr-resources-for-endo

Sources of Research Support: NIH R01 DK61935 (MJT)