Cross-talk between the glucocorticoid receptor and MyoD family inhibitor domain-containing protein provides a new mechanism for generating tissue-specific responses to glucocorticoids

Abstract

Glucocorticoids are primary stress hormones that regulate many physiological processes, and synthetic derivatives of these molecules are widely used in the clinic. The molecular factors that govern tissue specificity of glucocorticoids, however, are poorly understood. The actions of glucocorticoids are mediated by the glucocorticoid receptor (GR). To discover new proteins that interact with GR and modulate its function, we performed a yeast two-hybrid assay. The MyoD family inhibitor domain-containing protein (MDFIC) was identified as a binding partner for GR. MDFIC associated with GR in the cytoplasm of cells, and treatment with glucocorticoids resulted in the dissociation of the GR-MDFIC complex. To investigate the function of the GR-MDFIC interaction, we performed a genome-wide microarray in intact and MDFIC-deficient A549 cells that were treated with glucocorticoids. A large cohort of genes was differentially regulated by GR depending on the presence or absence of MDFIC. These gene changes were strongly associated with inflammation, and glucocorticoid regulation of the inflammatory response was altered in MDFIC-deficient cells. At a molecular level, the interaction of MDFIC with GR altered the phosphorylation status of the receptor. We demonstrate in COS-1 cells that changes in receptor phosphorylation underlie the ability of MDFIC to regulate the transcriptional activity of GR. Finally, we show that GR directly represses the MDFIC gene, revealing a negative feedback loop by which glucocorticoids limit MDFIC activity. These findings identify a new binding partner for cytoplasmic GR that modulates the receptor transcriptome and contributes to the tissue-specific actions of glucocorticoids.

Estrogen Deficiency Promotes Hepatic Steatosis via a Glucocorticoid Receptor-Dependent Mechanism in Mice

“…Approximately 30 μg of total protein was resolved on a 4%–20% Tris-glycine gel (Bio-Rad) and transferred onto a 0.2 μM nitrocellulose membrane (Bio-Rad). Membranes were blocked with blocking buffer (LI-COR Biosciences, Lincoln, NE) and incubated overnight with either anti-GR 59 ( Oakley et al, 2017 ), anti-phosphoserine 211 GR (Cell Signaling Technology), anti-FSHR (Abcam), anti-hCGR (LHR, Abcam), or anti-β-actin (Millipore). Total GR, phosphorylated GR, FSHR, and LHR were used at 1:1,000, and β-actin was used at 1:10,000.…”

Growth Hormone(s), Testosterone, Insulin-Like Growth Factors, and Cortisol: Roles and Integration for Cellular Development and Growth With Exercise

“…Yet, glucocorticoid resistance may also be acquired and localized to the sites of inflammation (169) with pathological conditions (224). Glucocorticoid sensitivity is largely determined by a number of factors including the intracellular density and distribution of glucocorticoid receptors (183), 11βHSD1-mediated intracellular synthesis of active cortisol from inactive cortisone (179), tissue-specific presence of coregulatory proteins, the phosphorylation status of GR, the sequence of the GR-binding site and flanking DNA on target genes (184,225), post-translational modifications of GR, the availability of specific co-activators and co-repressors, epigenetic regulators, the chromatin landscape (187,190), and cross-talk with MyoD family inhibitor domain-containing proteins (226).…”

Opposite Roles of the JMJD1A Interaction Partners MDFI and MDFIC in Colorectal Cancer

“…Hence, MDFI and MDFIC may plausibly perform many functions unrelated to transcriptional coregulation on the chromatin, yet may affect some transcriptional regulators in the cytoplasm. And indeed, previous studies have shown that MDFIC binds to and affects the glucocorticoid receptor in the cytoplasm 13 , or that MDFI and MDFIC interact with the cytoplasmic AXIN1 protein and in this manner modulate levels of the transcriptional cofactor β-catenin 4 . It is as well conceivable that MDFI and MDFIC regulate JMJD1A activity in the cytoplasm, since this histone demethylase is also present to a large extent in the cytoplasm of colon cancer cells 19 where it may potentially demethylate cytoplasmic, non-histone proteins.…”

“…When cells were treated with glucocorticoid, this interaction dissolved and the receptor translocated into the cell nucleus while MDFIC stayed behind in the cytoplasm. Moreover, transcriptome analyses revealed that MDFIC can influence the inflammatory response mediated by the glucocorticoid receptor 13 . However, no Mdfic -/mouse model has yet been published that could corroborate these potential functions of MDFIC.…”