Abstract
The G protein-coupled receptor (GPCR) signaling pathways mediated by trimeric G proteins have been extensively elucidated, but their associated regulatory mechanisms remain unclear. Parathyroid hormone (PTH)/PTH-related protein receptor (PTHR) is a GPCR coupled with Gs and Gq. Gs activates adenylyl cyclases (ACs), which produces cAMP to regulate various cell fates. We previously showed that cell surface expression of PTHR was increased by its direct interaction with a subcortical cytoskeletal protein, 4.1G, whereas PTHR-mediated Gs/AC/cAMP signaling was suppressed by 4.1G through an unknown mechanism in human embryonic kidney (HEK)293 cells. In the present study, we found that AC type 6 (AC6), one of the major ACs activated downstream of PTHR, interacts with 4.1G in HEK293 cells, and the N-terminus of AC6 (AC6-N) directly and selectively binds to the 4.1/ezrin/radixin/moesin (FERM) domain of 4.1G (4.1G-FERM) in vitro. AC6-N was distributed at the plasma membrane, which was disturbed by knockdown of 4.1G. An AC6-N mutant, AC6-N-3A, in which three consecutive arginine residues are mutated to alanine residues, altered both binding to 4.1G-FERM and its plasma membrane distribution in vivo. Further, we overexpressed AC6-N to competitively inhibit the interaction of endogenous AC6 and 4.1G in cells. cAMP production induced by forskolin, an adenylyl cyclase activator, and PTH-(1-34) was enhanced by AC6-N expression and 4.1G-knockdown. In contrast, AC6-N-3A had no impact on forskolin- and PTH-(1-34)-induced cAMP productions. These data provide a novel regulatory mechanism that AC6 activity is suppressed by the direct binding of 4.1G to AC6-N, resulting in attenuation of PTHR-mediated Gs/AC6/cAMP signaling.
Footnotes
- Received February 22, 2019.
- Accepted July 30, 2019.
This work was supported by the Grant-in-Aid for Scientific Research from the Japan Society for Promotion of Science (No. 15K20856 and No. 18K06125 to M.S., No. 24590311 to T.Y., No. 18K06885 to T.S., and No. 21200007, No. 21590267, No. 26460331 to J.S.), Takeda Science Foundation, Nishinomiya Basic Research Fund (to M.S.), and Shokei Gakuin University (to J.S.). Conflict of interest: The authors declare that they have no conflict of interest.
↵This article has supplemental material available at molpharm.aspetjournals.org.
- Copyright © 2019 by The American Society for Pharmacology and Experimental Therapeutics