Abstract 14836: Dual Dysfunction of Kir2.1 at the Sarcolemma and the Sarcoplasmic Reticulum Underlies Arrhythmogenesis in a Mouse Model of the Andersen-Tawil Syndrome Type 1

Introduction: Andersen-Tawil syndrome type 1 (ATS1) is associated with fatal cardiac arrhythmias. However, the underlying mechanisms are poorly understood. Hypothesis: Cardiac-specific expression of trafficking deficient Kir2.1 channels in mice in-vivo recapitulates the cardiac electrical phenotype of ATS1 and investigate the underlying mechanisms. Methods: We generated a new mouse model of ATS1 by a single i.v. injection of cardiac specific adeno-associated viral (AAV) transduction with Kir2.1 Δ314-315 , which recapitulated the ATS1 ECG phenotype without modifying ventricular function. The animal and cellular, structural and functional analyses were carried out by ECG, intracardiac stimulation, patch-clamping, membrane fractionation, western blot, immunolocalization and live calcium imaging. Results: AAV-Kir2.1 Δ314-315 mice were significantly more sensitive to flecainide than control, increasing the PR and QRS intervals over time. Kir2.1 Δ314-315 mice had increased vulnerability to cardiac fibrillation. Patch-clamping in ventricular cardiomyocytes from Kir2.1 Δ314-315 mice demonstrated significantly reduced I K1 and I Na , depolarized resting membrane potential and prolonged action potential. Immunolocalization in control mice revealed two bands of Kir2.1 staining, one colocalizing with Na V 1.5 and AP1 near the Z disk, the other near the H zone. Membrane fractionation and western blot experiments demonstrated two distinct levels of Kir2.1 protein expression, one at the sarcolemmal fraction together with Na V 1.5 and the other at the sarcoplasmi creticulum (SR). Kir2.1 Δ314-315 cardiomyocytes showed disruption of the Kir2.1-Nav1.5 channelosome at the sarcolemma, indicating dysfunctional trafficking o fboth channels. In addition, the SR Kir2.1 was disrupted and calcium transient dynamics were altered, resulting in frequent abnormal spontaneous calcium release events, and revealing an excitation-contraction coupling defect. Conclusions: Cardiac-specific AAV transduction with Kir2.1 Δ314-315 in mice recapitulates the ATS1 phenotype by disrupting localization and function of Kir2.1at the SR, and the Kir2.1-Na V 1.5 channelosome at the sarcolemma, revealing anovel dual mechanism of arrhythmogenesis.

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Abstract P356: Dual Dysfunction Of Kir2.1 Underlies Conduction And Excitation-contraction Coupling Defects Promoting Arrhythmias In A Mouse Model Of Andersen-tawil Syndrome Type 1

Circulation Research ◽

10.1161/res.129.suppl_1.p356 ◽

2021 ◽

Vol 129 (Suppl_1) ◽

Author(s):

Alvaro Macias ◽

Andrés González-Guerra ◽

Ana I. Moreno-Manuel ◽

Francisco M. Cruz ◽

Nieves García-Quintáns ◽

...

Keyword(s):

Mouse Model ◽

Intracellular Calcium ◽

Inward Rectifier ◽

Polymorphic Ventricular Tachycardia ◽

Resting Membrane Potential ◽

Syndrome Type ◽

Inward Currents ◽

And Function

Background: Andersen-Tawil syndrome type 1 (ATS1), caused by trafficking deficient mutations in the gene KCNJ2 coding the inward rectifier K + channel Kir2.1, is associated with life-threatening arrhythmias, which in some patients resemble catecholaminergic polymorphic ventricular tachycardia (CPVT), but the mechanisms are poorly understood. We tested the hypothesis that dysfunction of two different populations of mutant Kir2.1 channels, one at the sarcolemma, and the other at the sarcoplasmic reticulum (SR) membrane, directly alters conduction and intracellular calcium dynamics, respectively, to promote the ATS1 phenotype and arrhythmias that resemble CPVT. Methods: We generated a new mouse model of ATS1 by a single i.v. injection of cardiac specific adeno-associated viral (AAV) transduction with Kir2.1 Δ314-315 . In-vivo and cellular, structural and functional analyses of the model were carried out by electrocardiogram (ECG), magnetic resonance imaging (MRI), intracardiac stimulation, patch-clamping, membrane fractionation, western blot, immunolocalization and live calcium imaging. Results: Our mouse model carrying mutant Kir2.1 Δ314-315 recapitulated the ATS1 phenotype without modifying ventricular function. On ECG, Kir2.1 Δ314-315 mice had prolonged PR, QRS and QT intervals and occasional U waves. They showed significantly slower conduction velocities than wildtype mice in response to flecaidine-induced Na + -channel blockade, additional QT prolongation in response to isoproterenol, and increased vulnerability to cardiac fibrillation. Cardiomyocytes from Kir2.1 Δ314-315 mice had significantly reduced inward rectifier K + and Na + inward currents, depolarized resting membrane potential and prolonged action potential duration. Immunolocalization in wildtype cardiomyocytes and skeletal muscle cells revealed a novel SR microdomain of functional Kir2.1 channels contributing to intracellular Ca 2+ homeostasis. Kir2.1 Δ314-315 cardiomyocytes showed defects in SR Kir2.1 localization and function, which contributed to abnormal spontaneous Ca 2+ release events. Conclusions: Cardiac-specific AAV transduction with Kir2.1 Δ314-315 in mice recapitulates the ATS1 phenotype by disrupting localization and function of Kir2.1 channels at the SR, and the Kir2.1-Na V 1.5 channelosome at the sarcolemma. These results reveal a novel dual mechanism of arrhythmogenesis in ATS1 involving defects in Kir2.1 channel trafficking and function at two different microdomains. They also provide the first demonstration at the molecular level of the mechanism underlying the overlap between ATS1 and CPVT associated with defects in intracellular calcium homeostasis.

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The Mouse Model of Autoimmune Polyglandular Syndrome Type 1

Immunoendocrinology: Scientific and Clinical Aspects ◽

10.1007/978-1-60327-478-4_6 ◽

2010 ◽

pp. 95-113

Author(s):

James Gardner ◽

Mark Anderson

Keyword(s):

Mouse Model ◽

Syndrome Type ◽

Autoimmune Polyglandular Syndrome ◽

Autoimmune Polyglandular Syndrome Type

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AAV9‐mediated AIRE gene delivery clears circulating antibodies and tissue T‐cell infiltration in a mouse model of autoimmune polyglandular syndrome type‐1

Clinical & Translational Immunology ◽

10.1002/cti2.1166 ◽

2020 ◽

Vol 9 (9) ◽

Author(s):

Sarah Almaghrabi ◽

Mimoun Azzouz ◽

Rachid Tazi Ahnini

Keyword(s):

T Cell ◽

Gene Delivery ◽

Mouse Model ◽

Syndrome Type ◽

Autoimmune Polyglandular Syndrome ◽

T Cell Infiltration ◽

Aire Gene ◽

Circulating Antibodies ◽

Autoimmune Polyglandular Syndrome Type

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Dual Dysfunction of Kir2.1 Underlies Conduction and Excitation-Contraction Coupling Defects Promoting Arrhythmias in a Mouse Model of Andersen-Tawil Syndrome Type 1

10.1101/2021.06.17.448833 ◽

2021 ◽

Author(s):

Alvaro Macias ◽

Andres Gonzalez-Guerra ◽

Ana I. Moreno-Manuel ◽

Francisco M Cruz ◽

Nieves Garcia-Quintans ◽

...

Keyword(s):

Mouse Model ◽

Polymorphic Ventricular Tachycardia ◽

Resting Membrane Potential ◽

Inward Currents ◽

Life Threatening ◽

And Function ◽

Prolonged Action Potential Duration ◽

Kir2.1 Channel

Andersen-Tawil Syndrome (ATS) is associated with life threatening arrhythmias of unknown mechanism. We report on a mouse model carrying the trafficking-deficient mutant Kir2.1Δ314-315. The mouse recapitulates the electrophysiological phenotype of type 1 (ATS1), with slower conduction velocities in response to flecainide, QT prolongation exacerbated by isoproterenol, and increased vulnerability to calcium-mediated arrhythmias resembling catecholaminergic polymorphic ventricular tachycardia (CPVT). Kir2.1Δ314-315 expression significantly reduced inward rectifier K+ and Na+ inward currents, depolarized resting membrane potential and prolonged action potential duration. Immunolocalization in wildtype cardiomyocytes and skeletal muscle cells revealed a novel sarcoplasmic reticulum (SR) microdomain of functional Kir2.1 channels contributing to intracellular Ca2+ homeostasis. Kir2.1Δ314-315 cardiomyocytes showed defects in SR Kir2.1 localization and function, which contributed to abnormal spontaneous Ca2+ release events. This is the first in-vivo demonstration of a dual arrhythmogenic mechanism of ATS1 defects in Kir2.1 channel function at the sarcolemma and the SR, with overlap between ATS1 and CPVT.

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Challenges in the Diagnostic Conceptualization of CRPS-1 (Formerly Conceptualized as RSD)

Guides Newsletter ◽

10.1001/amaguidesnewsletters.2006.marapr01 ◽

2006 ◽

Vol 11 (2) ◽

pp. 1-3, 9-12

Author(s):

Robert J. Barth ◽

Tom W. Bohr

Keyword(s):

Clinical Practice ◽

Complex Regional Pain Syndrome ◽

Somatoform Disorders ◽

International Association ◽

Pain Syndrome ◽

Somatoform Disorder ◽

Syndrome Type ◽

Previous Issue

Abstract From the previous issue, this article continues a discussion of the potentially confusing aspects of the diagnostic formulation for complex regional pain syndrome type 1 (CRPS-1) proposed by the International Association for the Study of Pain (IASP), the relevance of these issues for a proposed future protocol, and recommendations for clinical practice. IASP is working to resolve the contradictions in its approach to CRPS-1 diagnosis, but it continues to include the following criterion: “[c]ontinuing pain, which is disproportionate to any inciting event.” This language only perpetuates existing issues with current definitions, specifically the overlap between the IASP criteria for CRPS-1 and somatoform disorders, overlap with the guidelines for malingering, and self-contradiction with respect to the suggestion of injury-relatedness. The authors propose to overcome the last of these by revising the criterion: “[c]omplaints of pain in the absence of any identifiable injury that could credibly account for the complaints.” Similarly, the overlap with somatoform disorders could be reworded: “The possibility of a somatoform disorder has been thoroughly assessed, with the results of that assessment failing to produce any consistencies with a somatoform scenario.” The overlap with malingering could be addressed in this manner: “The possibility of malingering has been thoroughly assessed, with the results of that assessment failing to produce any consistencies with a malingering scenario.” The article concludes with six recommendations, and a sidebar discusses rating impairment for CRPS-1 (with explicit instructions not to use the pain chapter for this purpose).

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