Differential regulation of glucocorticoid and progesterone receptor subcellular localization by tetratricopeptide repeat domain proteins
Year: 2007
Type: article
Abstract: Steroid-receptor associated immunophilins not only act in a coordinated manner to establish and maintain receptor conformation optimal for signaling but also play a critical role in determining receptor localization. To demonstrate TPR preference in steroid receptor localization, we chose a mouse fibroblast cell line, which expresses high levels of endogenous GR, and a Chinese hamster ovary, derived cell line, WCL2, that over-expresses mouse GR localized in the nucleus in the unliganded condition. Immunofluorescence and fractionation studies showed that although GR is predominantly nuclear in the WCL2 cells, it is not tightly bound to this compartment and is released into the cytosolic fraction upon cell lysis. Comparing the differences in the equilibrium levels of FKBP51 and FKBP52 between L929 and WCL2 not only revealed a very cell-type specific expression pattern but also hinted at the possibility of differential recruitment. Analysis of heterocomplex composition identified FKBP52 as the major TPR in WCL2 cells while FKBP51 was preferentially recruited into GR complexes from L929 cells. Having demonstrated the TPR preferences of GR in both cell types, we over- expressed FLAG-tagged FKBP51 and FKBP52 to determine if receptor subcellular localization could be altered by changing the equilibrium levels of these proteins. Receptor heterocomplexes in WCL2 showed a greater cytoplasmic distribution resulting from the recruitment of FLAG-tagged FKBP51, while distribution of GR in L929 cells remained unaffected by the distribution of flag-tagged FKBP52. To assess if the subcellular localization of other steroid receptors as well hinged on their preference towards specific TPR proteins, GFP fluorescence and co-
Author: Ananya Banerjee
Institution: University of Toledo
Language: English
Subfield: Endocrinology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2214517705