Prolonged AT1R activation induces CaV1.2 channel internalization in rat cardiomyocytes

Abstract

The cardiac L-type calcium channel is a multi-subunit complex that requires co-assembling of the pore-forming subunit CaV1.2 with auxiliary subunits CaVα2δ and CaVβ. Its traffic has been shown to be controlled by these subunits and by the activation of various G-protein coupled receptors (GPCR). Here, we explore the consequences of the prolonged activation of angiotensin receptor type 1 (AT1R) over CaV1.2 channel trafficking. Bioluminescence Resonance Energy Transfer (BRET) assay between β-arrestin and L-type channels in angiotensin II-stimulated cells was used to assess the functional consequence of AT1R activation, while immunofluorescence of adult rat cardiomyocytes revealed the effects of GPCR activation on CaV1.2 trafficking. Angiotensin II exposure results in β-arrestin1 recruitment to the channel complex and an apparent loss of CaV1.2 immunostaining at the T-tubules. Accordingly, angiotensin II stimulation causes a decrease in L-type current, Ca2+ transients and myocyte contractility, together with a faster repolarization phase of action potentials. Our results demonstrate that prolonged AT1R activation induces β-arrestin1 recruitment and the subsequent internalization of CaV1.2 channels with a half-dose of AngII on the order of 100 nM, suggesting that this effect depends on local renin-angiotensin system. This novel AT1R-dependent CaV1.2-trafficking modulation likely contributes to angiotensin II-mediated cardiac remodeling.

Presynaptic L-Type Ca2+ Channels Increase Glutamate Release Probability and Excitatory Strength in the Hippocampus during Chronic Neuroinflammation

“…Synaptic boutons along neurites (10 mm starting from the cell body) were automatically counted using ImageJ (Esposito et al, 2019). The presynaptic localization of the L-type Ca 21 channel was analyzed in treated neurons by evaluating the immunoreactivity of L-type Ca 21 channel (1:200, Alomone Labs) (Hermosilla et al, 2017) in vGLUT1-positive excitatory boutons. The area of colocalization puncta and the percentage of colocalization were automatically evaluated using ImageJ.…”

The endocytosis of oxidized LDL via the activation of the angiotensin II type 1 receptor

“…It has been increasingly recognized that heterodimerization of GPCRs could bias the signaling pathway of the partner receptor ( Ferre et al., 2014 ; Forrester et al., 2018 ). It has also been reported that ligand binding to GPCRs triggers signal transduction modified by interactions with non-GPCRs, such as ion channels ( Hermosilla et al., 2017 ; Shenoy and Lefkowitz, 2011 ; Shukla et al., 2010 ). However, our previous study is the only example of ligand binding to single transmembrane receptor-induced activation of an adjacent GPCR in the oligomeric complex ( Yamamoto et al., 2015 ).…”

Endocytosis: A Turnover Mechanism Controlling Ion Channel Function

“…Similarly, sustained angiotensin II stimulation of angiotensin receptor type 1 (AT1R) on the Ca v 1.2 calcium channel induces β-arrestin 1 recruitment to the channel complex, causing the internalization of Ca v 1.2 in T-tubules. Therefore, L-type calcium currents decrease by ≈60%, and calcium transient amplitude and action potential duration decrease [ 91 ].…”