Hepatic estrogen-related receptor gamma is a key regulator of GDF15 production in acute and chronic liver injury

Abstract

Aims: Growth differentiation factor 15 (GDF15) is a stress-induced hepatokine with emerging roles in liver injury. Estrogen-related receptor γ (ERRγ), a nuclear receptor regulating mitochondrial function and metabolic stress, has also been implicated in various liver injury conditions. However, the regulatory interplay between ERRγ and GDF15 remains unclear. This study investigates the molecular mechanisms underlying GDF15 expression and secretion in the liver, focusing on the role of ERRγ during acute and chronic liver injury.

Materials and methods: Wild-type and hepatocyte-specific ERRγ knockout (ERRγ-LKO) mice were administered with a single dose of carbon tetrachloride (CCl₄) or fed an alcohol-containing diet for 4 weeks to establish acute or chronic liver injury models, respectively. ERRγ was overexpressed through an adenoviral construct (Ad-ERRγ). The ERRγ-specific inverse agonist GSK5182 was employed to inhibit the transactivation of ERRγ. The luciferase reporter assays were used to assess the binding of ERRγ protein to the regulatory region of GDF15 gene.

Key findings: Hepatic ERRγ and GDF15 gene expression, and GDF15 protein secretion were significantly elevated in both acute and chronic liver injury. Adenovirus-mediated overexpression of ERRγ is sufficient to substantially increase hepatic GDF15 expression and secretion. Genetic ablation of ERRγ expression or pharmacological inhibition of ERRγ transactivation substantially inhibited the upregulation of hepatic GDF15 expression and production in both acute and chronic liver injury. Furthermore, reporter assays showed that ERRγ, but not ERRα or ERRβ, directly binds to and activates the GDF15 gene promoter.

Significance: Our findings highlight the crucial role of ERRγ in transcriptional regulation of GDF15 gene expression and production in response to liver damage. Understanding the regulatory mechanisms of GDF15 expression could lead to new therapeutic targets for protecting the liver from various types of injuries and associated diseases.

Keywords: CB1R; ERRγ; GDF15; Gene expression; Orphan nuclear receptor; Transcriptional regulation.