NeuroD Factors Discriminate Mineralocorticoid From Glucocorticoid Receptor DNA Binding in the Male Rat Brain.

Lisa T.C.M Van Weert,Benno Roozendaal,Pamela S.M Braakhuis,Nicole A Datson,Jacobus C Buurstede,Hetty C.M Sips,E Ronald De Kloet,Onno C Meijer,J Annelies E Polman,Judit Balog,Ahmed Mahfouz

doi:10.1210/en.2016-1422

Lisa T.C.M Van Weert, Benno Roozendaal + Show 9 more

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https://doi.org/10.1210/en.2016-1422

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Abstract

In the limbic brain, mineralocorticoid receptors (MRs) and glucocorticoid receptors (GRs) both function as receptors for the naturally occurring glucocorticoids (corticosterone/cortisol) but mediate distinct effects on cellular physiology via transcriptional mechanisms. The transcriptional basis for specificity of these MR- vs GR-mediated effects is unknown. To address this conundrum, we have identified the extent of MR/GR DNA-binding selectivity in the rat hippocampus using chromatin immunoprecipitation followed by sequencing. We found 918 and 1450 nonoverlapping binding sites for MR and GR, respectively. Furthermore, 475 loci were co-occupied by MR and GR. De novo motif analysis resulted in a similar binding motif for both receptors at 100% of the target loci, which matched the known glucocorticoid response element (GRE). In addition, the Atoh/NeuroD consensus sequence was found in co-occurrence with all MR-specific binding sites but was absent for GR-specific or MR-GR overlapping sites. Basic helix-loop-helix family members Neurod1, Neurod2, and Neurod6 showed hippocampal expression and were hypothesized to bind the Atoh motif. Neurod2 was detected at rat hippocampal MR binding sites but not at GR-exclusive sites. All three NeuroD transcription factors acted as DNA-binding-dependent coactivators for both MR and GR in reporter assays in heterologous HEK293 cells, likely via indirect interactions with the receptors. In conclusion, a NeuroD family member binding to an additional motif near the GRE seems to drive specificity for MR over GR binding at hippocampal binding sites.

Highlights

In the limbic brain, mineralocorticoid receptors (MRs) and glucocorticoid receptors (GRs) both function as receptors for the naturally occurring glucocorticoids but mediate distinct effects on cellular physiology via transcriptional mechanisms
After uniquely mapping 66.6% to 83.5% of these reads to the rat genome, model-based analysis of ChIP-Seq (MACS) peak calling with a false discovery rate cutoff at 13.5% [conform [12]; Supplemental Fig. 1(a)] resulted in 768 MR sites in the animals injected with 300 mg/kg (MR300) and 1465 MR sites and 2460 GR sites in the animals injected with 3000 mg/kg (MR3000 and GR3000)
This study examined the overlap and specificity of MR vs GR regarding whole-genome hippocampal binding sites

Summary

Introduction

Mineralocorticoid receptors (MRs) and glucocorticoid receptors (GRs) both function as receptors for the naturally occurring glucocorticoids (corticosterone/cortisol) but mediate distinct effects on cellular physiology via transcriptional mechanisms. The transcriptional basis for specificity of these MRvs GR-mediated effects is unknown To address this conundrum, we have identified the extent of MR/GR DNA-binding selectivity in the rat hippocampus using chromatin immunoprecipitation followed by sequencing. In the dorsal pyramidal cells, GR-mediated actions oppose those mediated by MR [10] That these MR- and GR-mediated effects of corticosterone are sometimes overlapping and, in other processes, are distinct is remarkable, given the large structural similarity between the two receptor types. The fact that the two receptors are 94% identical in their DBD [16] suggests that other mechanisms must exist that confer transcriptional specificity underlying the differential effects of MR/GR

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