Modulation of transcriptional mineralocorticoid receptor activity by casein kinase 2

Area of Science:

• Cardiovascular Biology
• Molecular Endocrinology
• Inflammation Research

Background:

• Cardiovascular disease pathogenesis involves complex processes including the mineralocorticoid receptor (MR).
• MR activity is influenced by inflammatory cytokines and posttranslational modifications like phosphorylation.
• Casein kinase 2 (CK2), a serine/threonine kinase, is activated during inflammation and can modulate MR.

Purpose of the Study:

• To investigate the role of CK2 in regulating MR activity.
• To identify the specific interaction site and mechanism between CK2 and MR.
• To determine the impact of CK2-MR interaction on inflammatory gene expression.

Main Methods:

• Sequence analysis and inhibitor experiments to assess CK2's effect on MR.
• Peptide microarrays and site-directed mutagenesis to identify phosphorylation sites.
• Co-immunoprecipitation to demonstrate MR-CK2 protein-protein interaction.
• Cytokine stimulation assays to evaluate gene expression changes.

Main Results:

• CK2 positively modulates MR activity by facilitating MR-DNA interaction and promoting MR degradation.
• Serine 459 (S459) was identified as a key CK2 phosphorylation site on MR.
• HSP90 mediates MR-CK2 protein-protein interaction.
• Inflammation-induced cytokine stimulation enhances CK2-dependent pro-inflammatory gene expression, further augmented by aldosterone-activated MR.

Conclusions:

• CK2 acts as a positive regulator of MR, influencing its DNA binding and degradation.
• The interaction between CK2 and MR, particularly at S459, plays a significant role in inflammatory responses.
• Bidirectional CK2-MR interaction in an inflammatory environment exacerbates cardiovascular disease pathophysiology.