A nuclear function of β-arrestin1 in GPCR signaling:: Regulation of histone acetylation and gene transcription

Chromatin modification is considered to be a fundamental mechanism of regulating gene expression to generate coordinated responses to environmental changes, however, whether it could be directly regulated by signals mediated by G protein-coupled receptors (GPCRs), the largest surface receptor family, is not known. Here, we show that stimulation of delta-opioid receptor, a member of the GPCR family, induces nuclear translocation of beta-arrestin 1 (beta arr1), which was previously known as a cytosolic regulator and scaffold of GPCR signaling. In response to receptor activation, beta arr1 translocates to the nucleus and is selectively enriched at specific promoters such as that of p27 and c-fos, where it facilitates the recruitment of histone acetyltransferase p300, resulting in enhanced local histone H4 acetylation and transcription of these genes. Our results reveal a novel function of beta arr1 as a cytoplasm-nucleus messenger in GPCR signaling and elucidate an epigenetic mechanism for direct GPCR signaling from cell membrane to the nucleus through signal-dependent histone modification.