# GPR3 is an immediate-early gene-like GPCR regulating CREB-dependent neuronal differentiation

## TL;DR

GPR3 is a GPCR that acts like an immediate-early gene, helping regulate neuronal differentiation through CREB-dependent signaling.

## Contribution

GPR3 is identified as an immediate-early gene-like GPCR that amplifies cAMP-CREB signaling during neuronal differentiation.

## Key findings

- Gpr3 is rapidly induced by NGF and cAMP in PC12 cells with biphasic activation.
- Early Gpr3 induction enhances Nr4a1–3 and Synapsin1 transcription via CREB signaling.
- Gpr3 deletion reduces Nr4a1–3 and Syn1 expression in primary cortical neurons.

## Abstract

GPR3 is a constitutively active Gs-coupled receptor whose transcriptional regulation during neuronal differentiation has remained unclear. Here, we identify Gpr3 as an immediate-early gene-like transcript rapidly induced by nerve growth factor (NGF) and cAMP signaling in PC12 cells, exhibiting biphasic activation captured by native elongating transcript-cap analysis of gene expression (NET-CAGE) at a core promoter ∼200 bp upstream of the transcription start site (TSS). Five cAMP response elements (CREs) within the 1-kb regulatory region cooperatively mediated stimulus-responsive transcription, with p-CREB enrichment selectively occurring at the proximal −34 CRE. Early Gpr3 induction enhanced delayed Nr4a1–3 expression and promoted Synapsin1 (Syn1) transcription through an Nr4a1-dependent mechanism. In primary cortical neurons, Gpr3 deletion diminished the developmental upregulation of Nr4a1–3 and Syn1 and reduced SYN1-positive vesicle density. These findings indicate GPR3 as an activity-dependent cAMP amplifier that couples early CREB activation to transcriptional programs governing NR4A signaling and presynaptic maturation during neuronal differentiation.

•GPR3 is a unique GPCR exhibiting immediate-early gene-like biphasic induction•Proximal CREs mediate rapid Gpr3 transcription through stimulus-dependent CREB binding•Early Gpr3 induction reinforces cAMP-CREB signaling to enhance Nr4a1–3 transcription•NR4A1 mediates GPR3-dependent Synapsin1 expression and presynaptic development

GPR3 is a unique GPCR exhibiting immediate-early gene-like biphasic induction

Proximal CREs mediate rapid Gpr3 transcription through stimulus-dependent CREB binding

Early Gpr3 induction reinforces cAMP-CREB signaling to enhance Nr4a1–3 transcription

NR4A1 mediates GPR3-dependent Synapsin1 expression and presynaptic development

Biological sciences; molecular neuroscience; systems neuroscience; cellular neuroscience