FUNCTIONAL CROSS-TALK BETWEEN THE GLU- COCORTICOID AND PROGESTERONE RECEPTORS IN MAMMARY EPITHELIAL CELLS

MARINI, MS; OGARA, MF; LEVI, V; VICENT, GP; PECCI, A

MAR DEL PLATA, BUENOS AIRES, ARGENTINA

Congreso; REUNION CONJUNTA SAIC SAI SAFIS 2018; 2018

SOCIEDAD ARGENTINA DE INVESTIGACIÓN CLÍNICA

Glucocorticoid (GR) and progesterone (PR) receptors are members of the steroid receptor family. Active PR is associated with cell proliferation and the progression of mammary tumors while GR promotes cell differentiation. Therefore, their relative abundance can modulate the proliferative response of the mammary epithelium. In view of these precedents, the objective of this work was to test the capacity of both receptors to be part of the same complex and study the differences in recruitment of chromatin remodelers to specific response regions where both receptors share binding sites. To assess PR and GR nuclear dynamics in vivo T47D cells were transfected with expression vectors encoding both receptors fused to fluorescent proteins (eGFPPR and mCherryGR) and incubated with their R5020 and/or Dex ligands, respectively. Then, fluorescence correlation spectroscopy (FCS) was used, which allows obtaining quantitative parameters related to the mobility of fluorescent molecules and their interaction with fixed targets in living cells. Results showed that when both receptors are activated, they move in the nucleus, simultaneously. Both, the GR ligand binding domain and the DNA binding domain are involved in the interaction with the PR. Upon activation with their respective ligands, both receptors are also recruited to a large fraction of specific binding regions. This result led us to investigate which chromatin remodelers are recruited in these regions and what differences exist between them when both receptors are treated simultaneously with their specific hormones. ChIPs assays were performed for p300, BRG1 and Foxa1 in T47D A1-2 cells expressing GR and PR and in T47D cells expressing PR only. We analyzed specific regions located in GREB1, STAT5A, SNAI1 and ELF5 genes. Taken together, 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.