ANALYSIS OF THE INTERACTION BETWEEN THE GLUCOCORTICOID AND THE PROGESTERONE RECEPTORS

MARINI, MS; OGARA, MF; STORTZ, M; LEVI, V

Ciudad Autónoma de Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

Glucocorticoid (GR) and progesterone (PR) receptors are members of the steroid receptors family. The active PR is associated with cell proliferation and mammary tumors progression. GR activation promotes cell differentiation. Thus, the relative abundance of both receptors may modulate the proliferative response of the mammary epithelium. In view of these precedents, the aim of this work was to test the ability of both receptors to be part of the same complex and to study if both receptors are able to be recruited at the same binding regions in the genome. To assess if PR and GR have the potential to form complexes in vivo, T47D cells were transfected with expression vectors encoding for both receptors fused to fluorescent proteins (eGFPPR and mCherryGR) and incubated with their ligands R5020 and/or Dex, respectively. Then, fluorescence correlation spectroscopy (FCS), which allows obtaining quantitative parameters related to the mobility of fluorescent molecules and their interaction with fixed targets in living cells was used. From these analyzes it was observed that when both receptors are activated, they move in the nucleus, simultaneously. Upon activation with their respective ligands, both receptors are also recruited to a large fraction of specific binding regions. This result led us to inquire whether receptor co-binding at these regions could occur upon simultaneous treatment with their specific hormones. Thus, sequential ChIP for the PR/GR was performed in T47D/A1-2 cells which express comparable levels of both receptors. We found that indeed GR and PR co-bind to specific regions located in the CD44, GREB1, STAT5A, SNAI1 and ELF5 genes. Altogether these results suggest that PR and GR could be part of the same protein complex and play an important role in the cellular response of the mammary epithelium.