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 β-arrestin 1 (βarr1), which was previously known as a cytosolic regulator and scaffold of GPCR signaling. In response to receptor activation, βarr1 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 βarr1 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.