Membrane glucocorticoid receptor activation induces proteomic changes aligning with classical glucocorticoid effects

Sara Vernocchi, Nadia Battello, Stephanie Schmitz, Dominique Revets, Anja Billing, Jonathan D. Turner, Claude P. Muller

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

Glucocorticoids exert rapid nongenomic effects by several mechanisms including the activation of a membrane-bound glucocorticoid receptor (mGR). Here, we report the first proteomic study on the effects of mGR activation by BSA-conjugated cortisol (Cort-BSA). A subset of target proteins in the proteomic data set was validated by Western blot and we found them responding to mGR activation by BSA-conjugated cortisol in three additional cell lines, indicating a conserved effect in cells originating from different tissues. Changes in the proteome of BSA-conjugated cortisol treated CCRF-CEM leukemia cells were associated with early and rapid pro-apoptotic, immunemodulatory and metabolic effects aligning with and possibly "priming" classical activities of the cytosolic glucocorticoid receptor (cGR). PCR arrays investigating target genes of the major signaling pathways indicated that the mGR does not exert its effects through the transcriptional activity of any of the most common kinases in these leukemic cells, but RhoA signaling emerged from our pathway analysis. All cell lines tested displayed very low levels of mGR on their surface. Highly sensitive and specific in situ proximity ligation assay visualized low numbers of mGR even in cells previously thought to be mGR negative. We obtained similar results when using three distinct anti-GR monoclonal antibodies directed against the N-terminal half of the cGR. This strongly suggests that the mGR and the cGR have a high sequence homology and most probably originate from the same gene. Furthermore, the mGR appears to reside in caveolae and its association with caveolin-1 (Cav-1) was clearly detected in two of the four cell lines investigated using double recognition proximity ligation assay. Our results indicate however that Cav-1 is not necessary for membrane localization of the GR since CCRF-CEM and Jurkat cells have a functional mGR, but did not express this caveolar protein. However, if expressed, this membrane protein dimerizes with the mGR modulating its function.

Original languageEnglish
Pages (from-to)1764-1779
Number of pages16
JournalMolecular and Cellular Proteomics
Volume12
Issue number7
DOIs
Publication statusPublished - 1 Jan 2013
Externally publishedYes

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ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Molecular Biology

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