AKAP complex regulates Ca ²⁺ re‐uptake into heart sarcoplasmic reticulum

Abstract

The b-adrenergic receptor/cyclic AMP/protein kinase A (PKA) signalling pathway regulates heart rate and contractility. Here, we identified a supramolecular complex consisting of the sarcoplasmic reticulum Ca 2 þ -ATPase (SERCA2), its negative regulator phospholamban (PLN), the A-kinase anchoring protein AKAP18d and PKA. We show that AKAP18d acts as a scaffold that coordinates PKA phosphorylation of PLN and the adrenergic effect on Ca 2 þ re-uptake. Inhibition of the compartmentalization of this cAMP signalling complex by specific molecular disruptors interferes with the phosphorylation of PLN. This prevents the subsequent release of PLN from SERCA2, thereby affecting the Ca 2 þ re-uptake into the sarcoplasmic reticulum induced by adrenergic stimuli.

Predicting the influence of long-range molecular interactions on macroscopic-scale diffusion by homogenization of the Smoluchowski equation

“…Such examples could include metabolic fluxes within the sarcomere 46,47 and "compartmentalized" cyclic adenosine monophosphate (cAMP) signaling via localized Akinase anchor proteins (AKAP) complexes. 48 We, furthermore, see the prospect of using the HSE to describe molecular phenomena well-represented by low-dimensional diffusional processes subject to a potential of mean force, such as the sliding of proteins along DNA. 49,50 …”

Culture and adenoviral infection of sinoatrial node myocytes from adult mice

“…Hearts were excised, and the ventricles removed. The sinoatrial node, defined as the region bordered by the crista terminalis, the interatrial septum, and the superior and inferior vena cavae (13,15,34,12,22,30), was microdissected at 35°C in a heparinized Tyrode's solution containing (in mM) 140 NaCl, 5.4 KCl, 1.2 KH 2PO4, 5 HEPES, 5.5 D-Glucose, 1 MgCl2, 1.8 CaCl2, and 100 USP/ml heparin, pH adjusted to 7.4 with NaOH. Sinoatrial node tissue was cut into three strips, which were enzymatically digested for 10 -15 min at 35°C with 3.75 mg Liberase TM (Roche, Basel, Switzerland) and 4.75 U elastase (Worthington Biochemical, Lakewood, NJ) in a modified Tyrode's solution containing (in mM) 140 NaCl, 5.4 KCl, 1.2 KH 2PO4, 5 HEPES, 18.5 D-glucose, 0.066 CaCl 2, 50 taurine, and 1 mg/ml BSA, pH adjusted to 6.9 with NaOH.…”

Specificity and spatial dynamics of protein kinase A signaling organized by A-kinase-anchoring proteins

“…Displacement of PLB from AKAP18d and siRNA knockdown experiments revealed that scaffolding of the complex by AKAP18d to allow precise spatiotemporal control of PKA phosphorylation of PLB is necessary for adrenergic effect on Ca 2C reuptake (Lygren et al 2007;Fig. 6).…”