Localization and ERK signaling of α1‐adrenergic subtypes in HeLa cells

Abstract

G‐protein coupled receptors (GPCRs), like α1‐adrenergic receptors (α1‐AR), are thought to localize to and signal at the plasma membrane, but many GPCRs localize to and signal at the nucleus in several cell types, including neurons, hepatocytes, and cardiac myocytes. Interestingly, α1‐ARs show differential localization based on cell type: nuclear in cardiac myocytes, but plasma membrane/intracellular in most cell lines and smooth muscle cells. Here, we examined receptor localization, oligomerization and signaling using HeLa cells as a cell model where α1‐ARs are not primarily at the nucleus. In HeLa cells, the α1A‐AR localized to the plasma membrane and nucleus, whereas the α1B‐AR localized intracellularly. Interestingly, co‐expression of both subtypes induced receptor hetero‐oligomer formation and produced a unique nuclear co‐localization. Activation of either subtype induced phosphorylation of ERK, which was unchanged by the membrane impermeant α1‐antagonist CGP‐12177a or the nuclear export inhibitor leptomycin B. These results suggest that, in contrast to other cells an intracellular, non‐nuclear α1‐AR population signals in HeLa cells. Signaling from intracellular α1‐AR and the localization differences between cell types could have implications in the treatment of hypertension and benign prostate hyperplasia. This work was supported by grants from NIH (TDO, CDW) and PhRMA Foundation (CDW).