Document Type
Article
Publication Date
1-22-2021
Publisher
Lippincott Williams & Wilkins, Inc.
Source Publication
Circulation Research
Source ISSN
0009-7330
Abstract
Rationale:
β1ARs (β1-adrenoceptors) exist at intracellular membranes and OCT3 (organic cation transporter 3) mediates norepinephrine entry into cardiomyocytes. However, the functional role of intracellular β1AR in cardiac contractility remains to be elucidated.
Objective:
Test localization and function of intracellular β1AR on cardiac contractility.
Methods and Results:
Membrane fractionation, super-resolution imaging, proximity ligation, coimmunoprecipitation, and single-molecule pull-down demonstrated a pool of β1ARs in mouse hearts that were associated with sarco/endoplasmic reticulum Ca2+-ATPase at the sarcoplasmic reticulum (SR). Local PKA (protein kinase A) activation was measured using a PKA biosensor targeted at either the plasma membrane (PM) or SR. Compared with wild-type, myocytes lacking OCT3 (OCT3-KO [OCT3 knockout]) responded identically to the membrane-permeant βAR agonist isoproterenol in PKA activation at both PM and SR. The same was true at the PM for membrane-impermeant norepinephrine, but the SR response to norepinephrine was suppressed in OCT3-KO myocytes. This differential effect was recapitulated in phosphorylation of the SR-pump regulator phospholamban. Similarly, OCT3-KO selectively suppressed calcium transients and contraction responses to norepinephrine but not isoproterenol. Furthermore, sotalol, a membrane-impermeant βAR-blocker, suppressed isoproterenol-induced PKA activation at the PM but permitted PKA activation at the SR, phospholamban phosphorylation, and contractility. Moreover, pretreatment with sotalol in OCT3-KO myocytes prevented norepinephrine-induced PKA activation at both PM and the SR and contractility.
Conclusions:
Functional β1ARs exists at the SR and is critical for PKA-mediated phosphorylation of phospholamban and cardiac contractility upon catecholamine stimulation. Activation of these intracellular β1ARs requires catecholamine transport via OCT3.
Recommended Citation
Wang, Ying; Shi, Qian; Li, Minghui; Zhao, Meimi; Gopireddy, Raghavender Reddy; Teoh, Jian-Peng; Xu, Bing; Zhu, Chaoqun; Ireton, Kyle E.; Srinivasan, Sanghavi; Chen, Shaoliang; Gasser, Paul J.; Bossuyt, Julie; Hell, Johannes W.; Bers, Donald M.; and Xiang, Yang K., "Intracellular β1-Adrenergic Receptors and Organic Cation Transporter 3 Mediate Phospholamban Phosphorylation to Enhance Cardiac Contractility" (2021). Biomedical Sciences Faculty Research and Publications. 204.
https://epublications.marquette.edu/biomedsci_fac/204
Comments
Accepted version. Circulation Research, Vol. 128, No. 2 (January 22, 2021): 246-261. DOI. © 2021 American Heart Association, Inc. published by Lippincott Williams & Wilkins, Inc. Used with permission.