A junctional cAMP compartment regulates rapid Ca2+ signaling in atrial myocytes
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A junctional cAMP compartment regulates rapid Ca2+ signaling in atrial myocytes. / Brandenburg, Sören; Pawlowitz, Jan; Steckmeister, Vanessa; Subramanian, Hariharan; Uhlenkamp, Dennis; Scardigli, Marina; Mushtaq, Mufassra; Amlaz, Saskia I; Kohl, Tobias; Wegener, Jörg W; Arvanitis, Demetrios A; Sanoudou, Despina; Sacconi, Leonardo; Hasenfuß, Gerd; Voigt, Niels; Nikolaev, Viacheslav O; Lehnart, Stephan E.
In: J MOL CELL CARDIOL, Vol. 165, 04.2022, p. 141-157.Research output: SCORING: Contribution to journal › SCORING: Journal article › Research › peer-review
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TY - JOUR
T1 - A junctional cAMP compartment regulates rapid Ca2+ signaling in atrial myocytes
AU - Brandenburg, Sören
AU - Pawlowitz, Jan
AU - Steckmeister, Vanessa
AU - Subramanian, Hariharan
AU - Uhlenkamp, Dennis
AU - Scardigli, Marina
AU - Mushtaq, Mufassra
AU - Amlaz, Saskia I
AU - Kohl, Tobias
AU - Wegener, Jörg W
AU - Arvanitis, Demetrios A
AU - Sanoudou, Despina
AU - Sacconi, Leonardo
AU - Hasenfuß, Gerd
AU - Voigt, Niels
AU - Nikolaev, Viacheslav O
AU - Lehnart, Stephan E
N1 - Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.
PY - 2022/4
Y1 - 2022/4
N2 - Axial tubule junctions with the sarcoplasmic reticulum control the rapid intracellular Ca2+-induced Ca2+ release that initiates atrial contraction. In atrial myocytes we previously identified a constitutively increased ryanodine receptor (RyR2) phosphorylation at junctional Ca2+ release sites, whereas non-junctional RyR2 clusters were phosphorylated acutely following β-adrenergic stimulation. Here, we hypothesized that the baseline synthesis of 3',5'-cyclic adenosine monophosphate (cAMP) is constitutively augmented in the axial tubule junctional compartments of atrial myocytes. Confocal immunofluorescence imaging of atrial myocytes revealed that junctin, binding to RyR2 in the sarcoplasmic reticulum, was densely clustered at axial tubule junctions. Interestingly, a new transgenic junctin-targeted FRET cAMP biosensor was exclusively co-clustered in the junctional compartment, and hence allowed to monitor cAMP selectively in the vicinity of junctional RyR2 channels. To dissect local cAMP levels at axial tubule junctions versus subsurface Ca2+ release sites, we developed a confocal FRET imaging technique for living atrial myocytes. A constitutively high adenylyl cyclase activity sustained increased local cAMP levels at axial tubule junctions, whereas β-adrenergic stimulation overcame this cAMP compartmentation resulting in additional phosphorylation of non-junctional RyR2 clusters. Adenylyl cyclase inhibition, however, abolished the junctional RyR2 phosphorylation and decreased L-type Ca2+ channel currents, while FRET imaging showed a rapid cAMP decrease. In conclusion, FRET biosensor imaging identified compartmentalized, constitutively augmented cAMP levels in junctional dyads, driving both the locally increased phosphorylation of RyR2 clusters and larger L-type Ca2+ current density in atrial myocytes. This cell-specific cAMP nanodomain is maintained by a constitutively increased adenylyl cyclase activity, contributing to the rapid junctional Ca2+-induced Ca2+ release, whereas β-adrenergic stimulation overcomes the junctional cAMP compartmentation through cell-wide activation of non-junctional RyR2 clusters.
AB - Axial tubule junctions with the sarcoplasmic reticulum control the rapid intracellular Ca2+-induced Ca2+ release that initiates atrial contraction. In atrial myocytes we previously identified a constitutively increased ryanodine receptor (RyR2) phosphorylation at junctional Ca2+ release sites, whereas non-junctional RyR2 clusters were phosphorylated acutely following β-adrenergic stimulation. Here, we hypothesized that the baseline synthesis of 3',5'-cyclic adenosine monophosphate (cAMP) is constitutively augmented in the axial tubule junctional compartments of atrial myocytes. Confocal immunofluorescence imaging of atrial myocytes revealed that junctin, binding to RyR2 in the sarcoplasmic reticulum, was densely clustered at axial tubule junctions. Interestingly, a new transgenic junctin-targeted FRET cAMP biosensor was exclusively co-clustered in the junctional compartment, and hence allowed to monitor cAMP selectively in the vicinity of junctional RyR2 channels. To dissect local cAMP levels at axial tubule junctions versus subsurface Ca2+ release sites, we developed a confocal FRET imaging technique for living atrial myocytes. A constitutively high adenylyl cyclase activity sustained increased local cAMP levels at axial tubule junctions, whereas β-adrenergic stimulation overcame this cAMP compartmentation resulting in additional phosphorylation of non-junctional RyR2 clusters. Adenylyl cyclase inhibition, however, abolished the junctional RyR2 phosphorylation and decreased L-type Ca2+ channel currents, while FRET imaging showed a rapid cAMP decrease. In conclusion, FRET biosensor imaging identified compartmentalized, constitutively augmented cAMP levels in junctional dyads, driving both the locally increased phosphorylation of RyR2 clusters and larger L-type Ca2+ current density in atrial myocytes. This cell-specific cAMP nanodomain is maintained by a constitutively increased adenylyl cyclase activity, contributing to the rapid junctional Ca2+-induced Ca2+ release, whereas β-adrenergic stimulation overcomes the junctional cAMP compartmentation through cell-wide activation of non-junctional RyR2 clusters.
KW - Adenylyl Cyclases/metabolism
KW - Adrenergic Agents
KW - Calcium/metabolism
KW - Calcium Signaling
KW - Cyclic AMP/metabolism
KW - Myocytes, Cardiac/metabolism
KW - Ryanodine Receptor Calcium Release Channel/metabolism
KW - Sarcoplasmic Reticulum/metabolism
U2 - 10.1016/j.yjmcc.2022.01.003
DO - 10.1016/j.yjmcc.2022.01.003
M3 - SCORING: Journal article
C2 - 35033544
VL - 165
SP - 141
EP - 157
JO - J MOL CELL CARDIOL
JF - J MOL CELL CARDIOL
SN - 0022-2828
ER -
