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

Area of Science:

• Cell Biology
• Molecular Endocrinology
• Proteomics

Background:

• Glucocorticoids mediate rapid, nongenomic effects via membrane-bound receptors (mGR).
• Understanding mGR's proteomic impact is crucial for elucidating its cellular functions.

Purpose of the Study:

• To investigate the proteomic changes induced by mGR activation using BSA-conjugated cortisol (Cort-BSA).
• To validate and characterize the cellular effects and signaling pathways influenced by mGR activation.

Main Methods:

• Proteomic analysis of CCRF-CEM leukemia cells treated with Cort-BSA.
• Western blot validation of target proteins across multiple cell lines.
• PCR arrays for signaling pathway analysis.
• Proximity ligation assays to detect mGR and its association with caveolin-1 (Cav-1).

Main Results:

• mGR activation by Cort-BSA induced rapid pro-apoptotic, immune-modulatory, and metabolic effects.
• RhoA signaling pathway emerged as a key mediator, distinct from common kinase pathways.
• mGR was detected at low levels on cell surfaces, even in previously considered negative cells.
• mGR likely originates from the same gene as cytosolic GR (cGR) and can associate with Cav-1, modulating its function.

Conclusions:

• mGR activation elicits rapid cellular responses that may prime cGR functions.
• RhoA signaling is implicated in mGR-mediated effects.
• mGR is present in various cell types and its interaction with Cav-1 influences its activity.