Voltage-gated Nav channel targeting in the heart requires an ankyrin-G–dependent cellular pathway

Lowe, John; Palygin, Oleg; Bhasin, Naina; Hund, Thomas J.; Boyden, Penelope A.; Shibata, Erwin F.; Anderson, Mark E.; Mohler, Peter J.

doi:10.1083/jcb.200710107

Cited by 157 publications

(146 citation statements)

References 84 publications

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“…31,32 Ankyrin-G is primarily expressed at the intercalated discs, with another population at T-tubules; it is therefore unlikely that it is responsible for the specific targeting of Na v 1.5 to the 2 compartments observed in our study. Whether the roles of syntrophin-dystrophin and ankyrin-G in trafficking, targeting, and anchoring of Na v 1.5 to the lateral membrane are complementary or partly redundant remains to be elucidated.…”

Section: Physiological Relevance Of the Two Regulating Mechanismsmentioning

confidence: 63%

SAP97 and Dystrophin Macromolecular Complexes Determine Two Pools of Cardiac Sodium Channels Na _v 1.5 in Cardiomyocytes

Petitprez

Zmoos

Ogrodnik³

et al. 2011

Circulation Research

243

237

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Rationale:The cardiac sodium channel Na v 1.5 plays a key role in excitability and conduction. The 3 last residues of Na v 1.5 (Ser-Ile-Val) constitute a PDZ-domain binding motif that interacts with the syntrophin-dystrophin complex. As dystrophin is absent at the intercalated discs, Na v 1.5 could potentially interact with other, yet unknown, proteins at this site.Objective: The aim of this study was to determine whether Na v 1.5 is part of distinct regulatory complexes at lateral membranes and intercalated discs. Methods and Results:Immunostaining experiments demonstrated that Na v 1.5 localizes at lateral membranes of cardiomyocytes with dystrophin and syntrophin. Optical measurements on isolated dystrophin-deficient mdx hearts revealed significantly reduced conduction velocity, accompanied by strong reduction of Na v 1.5 at lateral membranes of mdx cardiomyocytes. Pull-down experiments revealed that the MAGUK protein SAP97 also interacts with the SIV motif of Na v 1.5, an interaction specific for SAP97 as no pull-down could be detected with other cardiac MAGUK proteins (PSD95 or ZO-1). Furthermore, immunostainings showed that Na v 1.5 and SAP97 are both localized at intercalated discs. Silencing of SAP97 expression in HEK293 and rat cardiomyocytes resulted in reduced sodium current (I Na ) measured by patch-clamp. The I Na generated by Na v 1.5 channels lacking the SIV motif was also reduced. Finally, surface expression of Na v 1.5 was decreased in silenced cells, as well as in cells transfected with SIV-truncated channels. Conclusions:These data support a model with at least 2 coexisting pools of Na v 1.5 channels in cardiomyocytes: one targeted at lateral membranes by the syntrophin-dystrophin complex, and one at intercalated discs by SAP97. (Circ Res. 2011;108:294-304.) Key Words: sodium channel Ⅲ Na v 1.5 Ⅲ MAGUK proteins Ⅲ SAP97 Ⅲ dystrophin T he cardiac sodium channel Na v 1.5 initiates the cardiac action potential, thus playing a key role in cardiac excitability and impulse propagation. The physiological importance of this channel is illustrated by numerous cardiac pathologies caused by hundreds of mutations identified in SCN5A, the gene encoding Na v 1.5. 1 The Na v 1.5 channel is composed of one 220-kDa ␣-subunit that constitutes a functional channel, and 30-kDa ␤-subunits. In addition to these accessory ␤-subunits, several proteins have been shown to regulate and interact with Na v 1.5. 1,2 In most cases, the physiological relevance of these interactions is poorly understood, mainly because of a lack of appropriate animal models. Many of the interacting proteins bind to the C terminus of Na v 1.5, where several protein-protein interaction motifs are located. 1,2 We have shown that the ubiquitin-protein ligase Nedd4-2 binds the PY motif of Na v 1.5 and reduces the sodium current (I Na ) in HEK293 cells by promoting its internalization. 3 We have also demonstrated that Na v 1.5 associates with the dystrophin-syntrophin multiprotein complex (DMC) in cardiac cells. 4 In dystrophin-deficient mice (m...

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Section: Physiological Relevance Of the Two Regulating Mechanismsmentioning

confidence: 63%

SAP97 and Dystrophin Macromolecular Complexes Determine Two Pools of Cardiac Sodium Channels Na _v 1.5 in Cardiomyocytes

Petitprez

Zmoos

Ogrodnik³

et al. 2011

Circulation Research

243

237

View full text Add to dashboard Cite

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“…Ankyrin-G has been shown to play a role in the trafficking and anchoring of the cardiac sodium channel Nav1.5 (244,285), and, similar to that channel, ankyrin-G is also expressed at the intercalated discs and in the t-tubules of adult myocytes (283). Lowe et al (244) have shown that reduction of ankyrin-G expression in cardiac myocytes leads to reduced sodium currents and lowered Nav1.5 expression.…”

Section: Ankyrinsmentioning

confidence: 99%

“…Lowe et al (244) have shown that reduction of ankyrin-G expression in cardiac myocytes leads to reduced sodium currents and lowered Nav1.5 expression. This effect was specific for the ankyrin-G isoform, as this reduction was not observed in myocytes with reduced expression of ankyrin-B.…”

Section: Ankyrinsmentioning

confidence: 99%

Dynamic of Ion Channel Expression at the Plasma Membrane of Cardiomyocytes

Balse

Steele

Abriel

et al. 2012

Physiological Reviews

106

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Cardiac myocytes are characterized by distinct structural and functional entities involved in the generation and transmission of the action potential and the excitation-contraction coupling process. Key to their function is the specific organization of ion channels and transporters to and within distinct membrane domains, which supports the anisotropic propagation of the depolarization wave. This review addresses the current knowledge on the molecular actors regulating the distinct trafficking and targeting mechanisms of ion channels in the highly polarized cardiac myocyte. In addition to ubiquitous mechanisms shared by other excitable cells, cardiac myocytes show unique specialization, illustrated by the molecular organization of myocyte-myocyte contacts, e.g., the intercalated disc and the gap junction. Many factors contribute to the specialization of the cardiac sarcolemma and the functional expression of cardiac ion channels, including various anchoring proteins, motors, small GTPases, membrane lipids, and cholesterol. The discovery of genetic defects in some of these actors, leading to complex cardiac disorders, emphasizes the importance of trafficking and targeting of ion channels to cardiac function. A major challenge in the field is to understand how these and other actors work together in intact myocytes to fine-tune ion channel expression and control cardiac excitability.

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“…Furthermore, mice deficient in β IV -spectrin display defects in neuronal Na + channel clustering and function (29). In heart, ankyrin-G targets voltage-gated Na + channels (Na v 1.5) to the intercalated disc (43,44), and cardiac Na + channel membrane regulation has been associated with CaMKII activity (16). We therefore tested whether the β IV -spectrin/CaMKII complex formed a macromolecular complex with ankyrin-G and Na v 1.5 in heart.…”

Section: Introductionmentioning

confidence: 99%

A βIV-spectrin/CaMKII signaling complex is essential for membrane excitability in mice

Hund¹,

Koval²,

Li³

et al. 2010

J. Clin. Invest.

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231

289

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Ion channel function is fundamental to the existence of life. In metazoans, the coordinate activities of voltagegated Na + channels underlie cellular excitability and control neuronal communication, cardiac excitationcontraction coupling, and skeletal muscle function. However, despite decades of research and linkage of Na + channel dysfunction with arrhythmia, epilepsy, and myotonia, little progress has been made toward understanding the fundamental processes that regulate this family of proteins. Here, we have identified β IV -spectrin as a multifunctional regulatory platform for Na + channels in mice. We found that β IV -spectrin targeted critical structural and regulatory proteins to excitable membranes in the heart and brain. Animal models harboring mutant β IV -spectrin alleles displayed aberrant cellular excitability and whole animal physiology. Moreover, we identified a regulatory mechanism for Na + channels, via direct phosphorylation by β IV -spectrin-targeted calcium/calmodulin-dependent kinase II (CaMKII). Collectively, our data define an unexpected but indispensable molecular platform that determines membrane excitability in the mouse heart and brain.

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Voltage-gated Nav channel targeting in the heart requires an ankyrin-G–dependent cellular pathway

Cited by 157 publications

References 84 publications

SAP97 and Dystrophin Macromolecular Complexes Determine Two Pools of Cardiac Sodium Channels Na _v 1.5 in Cardiomyocytes

SAP97 and Dystrophin Macromolecular Complexes Determine Two Pools of Cardiac Sodium Channels Na _v 1.5 in Cardiomyocytes

Dynamic of Ion Channel Expression at the Plasma Membrane of Cardiomyocytes

A βIV-spectrin/CaMKII signaling complex is essential for membrane excitability in mice

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Voltage-gated Nav channel targeting in the heart requires an ankyrin-G–dependent cellular pathway

Cited by 157 publications

References 84 publications

SAP97 and Dystrophin Macromolecular Complexes Determine Two Pools of Cardiac Sodium Channels Na v 1.5 in Cardiomyocytes

SAP97 and Dystrophin Macromolecular Complexes Determine Two Pools of Cardiac Sodium Channels Na v 1.5 in Cardiomyocytes

Dynamic of Ion Channel Expression at the Plasma Membrane of Cardiomyocytes

A βIV-spectrin/CaMKII signaling complex is essential for membrane excitability in mice

Contact Info

Product

Resources

About

SAP97 and Dystrophin Macromolecular Complexes Determine Two Pools of Cardiac Sodium Channels Na _v 1.5 in Cardiomyocytes

SAP97 and Dystrophin Macromolecular Complexes Determine Two Pools of Cardiac Sodium Channels Na _v 1.5 in Cardiomyocytes