Abstract

Fibrosis or accumulation of extracellular matrix is an evolutionarily conserved mechanism adopted by an organism as a response to chronic injury. Excessive fibrosis, however, leads to disruption of organ homeostasis and is a common feature of many chronic diseases. G protein-coupled receptors (GPCRs) are important cell signaling mediators and represent molecular targets for many FDA approved drugs. To identify new targets for fibrosis, we utilized a synthetic GPCR system named Designed Receptors Exclusively Activated by Designer Drugs (DREADDs) to probe signaling pathways essential for fibrotic response. We found that upon expression in human lung fibroblasts, activation of Gq and Gs-DREADDs abrogated the induction of TGFβ-induced fibrosis marker genes. Genome-wide transcriptome analysis identified dysregulation of multiple GPCRs in lung fibroblasts treated with TGFβ. To investigate endogenous GPCR modulating TGFβ signaling, we selected 13 GPCRs that signal through Gq or Gs and activated them by using specific agonists. We examined the impact of each agonist and how activation of endogenous GPCR affects TGFβ signaling. Among which, prostaglandin receptor agonists demonstrated the strongest inhibitory effect on fibrosis. Together, we have demonstrated that DREADDs system is a valuable tool to identify beneficial GPCR signaling for fibrosis. This study in fibroblasts has served as a proof-of-concept and allowed us to further develop in vivo models for fibrosis GPCR discovery.

Significance Statement Fibrosis is the hallmark of many end-stage cardiometabolic diseases and there is an unmet medical need to discover new anti-fibrotic therapies, reduce disease progression, and bring clinically meaningful efficacy to patients. Our work utilizes DREADD chemogenetic tools to identify beneficial GPCR signaling for fibrosis, providing new insights into GPCR drug discovery.