Faculty Collaboration Database

Intracellular β₁-Adrenergic Receptors and Organic Cation Transporter 3 Mediate Phospholamban Phosphorylation to Enhance Cardiac Contractility. Circ Res 2021 Jan 22;128(2):246-261

Date

11/14/2020

Pubmed ID

33183171

Pubmed Central ID

PMC7856104

DOI

10.1161/CIRCRESAHA.120.317452

Scopus ID

2-s2.0-85100024815 (requires institutional sign-in at Scopus site)   35 Citations

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.

Author List

Wang Y, Shi Q, Li M, Zhao M, Reddy Gopireddy R, Teoh JP, Xu B, Zhu C, Ireton KE, Srinivasan S, Chen S, Gasser PJ, Bossuyt J, Hell JW, Bers DM, Xiang YK

Author

Paul Gasser BS,MS,PhD Assistant Professor in the Biomedical Sciences department at Marquette University

MESH terms used to index this publication - Major topics in bold

Adrenergic beta-Agonists
Adrenergic beta-Antagonists
Animals
Calcium-Binding Proteins
Cell Membrane
Cells, Cultured
Cyclic AMP-Dependent Protein Kinases
Female
Heart Rate
Male
Mice
Mice, Inbred C57BL
Mice, Knockout
Myocardial Contraction
Myocytes, Cardiac
Organic Cation Transport Proteins
Phosphorylation
Rabbits
Rats
Rats, Sprague-Dawley
Receptors, Adrenergic, beta-1
Receptors, Adrenergic, beta-2
Sarcoplasmic Reticulum
Signal Transduction