Syntaxin 1A Binds to the Cytoplasmic C Terminus of Kv2.1 to Regulate Channel Gating and Trafficking

Leung, Yuk‐Man; Kang, Youhou; Gao, Xiao‐Dong; Xia, Fuzhen; Xie, Huanli; Sheu, Laura; Tsuk, Sharon; Lotan, Ilana; Tsushima, Robert G.; Gaisano, Herbert Y.

doi:10.1074/jbc.m213088200

Cited by 118 publications

(145 citation statements)

References 26 publications

(49 reference statements)

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“…Previous work had shown that these t-SNAREs can bind to and regulate the gating of Kv2.1. [15][16][17][18] However, since the gating of the delayed rectifier does not change with apoptosis, 2 the neurotoxin results, in concert with our trafficking experiments, are most consistent with the requirement of t-SNARE proteins for the membrane fusion required for insertion of new channels into the cell surface. This conclusion also is in accordance with the observations that overexpression of syntaxin in cell lines inhibits exocytosis 19 and Kv2.1 surface expression.…”

Section: Discussionsupporting

confidence: 79%

“…This conclusion also is in accordance with the observations that overexpression of syntaxin in cell lines inhibits exocytosis 19 and Kv2.1 surface expression. 16 Of interest, t-SNARE proteins have also been implicated in the trafficking and/or surface expression of other plasma membrane channels, Figure 4 Surface delivery of Kv2.1(I376C) in cortical neurons during apoptosis. (a) Whole-cell K þ currents from Kv2.1(I379C)-expressing control (CON) cortical neurons or neurons triggered to undergo apoptosis (AP) by 100 mM DTDP (10 min).…”

Section: Discussionmentioning

confidence: 99%

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Apoptotic surface delivery of K+ channels

et al. 2005

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Apoptosis in cortical neurons requires efflux of cytoplasmic potassium mediated by a surge in Kv2.1 channel activity. Pharmacological blockade or molecular disruption of these channels in neurons prevents apoptotic cell death, while ectopic expression of Kv2.1 channels promotes apoptosis in non-neuronal cells. Here, we use a cysteine-containing mutant of Kv2.1 and a thiol-reactive covalent inhibitor to demonstrate that the increase in K þ current during apoptosis is due to de novo insertion of functional channels into the plasma membrane. Biotinylation experiments confirmed the delivery of additional Kv2.1 protein to the cell surface following an apoptotic stimulus. Finally, expression of botulinum neurotoxins that cleave syntaxin and synaptosome-associated protein of 25 kDa (SNAP-25) blocked upregulation of surface Kv2.1 channels in cortical neurons, suggesting that target soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins support proapoptotic delivery of K þ channels. These data indicate that trafficking of Kv2.1 channels to the plasma membrane causes the apoptotic surge in K þ current.

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Section: Discussionsupporting

confidence: 79%

Section: Discussionmentioning

confidence: 99%

Apoptotic surface delivery of K+ channels

et al. 2005

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“…In these experiments, we also confirmed the described association of syntaxin and Kv2.1 (Fig. 3A) (47)(48)(49). The increased CaMKII signal in Kv2.1-expressing cells could be the result of a direct interaction of the kinase with the K + channel.…”

Section: Injurious Oxidant Exposure Leads To Camkii Activation In Neusupporting

confidence: 75%

“…CaMKII has been shown to regulate exocytosis via a specific interaction with syntaxin (43)(44)(45)(46). In addition, syntaxin is known to bind to the most proximal region of the Kv2.1 C terminus, termed C1a, during Ca 2+ -facilitated exocytosis in pancreatic and other nonneuronal cells (47)(48)(49). Importantly, we showed that syntaxin is also required for the membrane insertion of Kv2.1 channels during apoptosis (23).…”

Section: Injurious Oxidant Exposure Leads To Camkii Activation In Neumentioning

confidence: 66%

Convergent Ca ²⁺ and Zn ²⁺ signaling regulates apoptotic Kv2.1 K ⁺ currents

McCord

Aizenman

2013

Proc. Natl. Acad. Sci. U.S.A.

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A simultaneous increase in cytosolic Zn 2+ and Ca 2+ accompanies the initiation of neuronal cell death signaling cascades. However, the molecular convergence points of cellular processes activated by these cations are poorly understood. Here, we show that Ca 2+ -dependent activation of Ca 2+ /calmodulin-dependent protein kinase II (CaMKII) is required for a cell death-enabling process previously shown to also depend on Zn 2+ . We have reported that oxidant-induced intraneuronal Zn 2+ liberation triggers a syntaxin-dependent incorporation of Kv2.1 voltage-gated potassium channels into the plasma membrane. This channel insertion can be detected as a marked enhancement of delayed rectifier K + currents in voltage clamp measurements observed at least 3 h following a short exposure to an apoptogenic stimulus. This current increase is the process responsible for the cytoplasmic loss of K + that enables protease and nuclease activation during apoptosis. In the present study, we demonstrate that an oxidative stimulus also promotes intracellular Ca 2+ release and activation of CaMKII, which, in turn, modulates the ability of syntaxin to interact with Kv2.1. Pharmacological or molecular inhibition of CaMKII prevents the K + current enhancement observed following oxidative injury and, importantly, significantly increases neuronal viability. These findings reveal a previously unrecognized cooperative convergence of Ca 2+ -and Zn 2+ -mediated injurious signaling pathways, providing a potentially unique target for therapeutic intervention in neurodegenerative conditions associated with oxidative stress.

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“…Syx and SNAP Directly Bind Cytosolic Domains of Kv2.1-Previously, we have shown in an in vitro binding assay that Syx and SNAP bind to the Kv2.1 channel (14,28). In this study we carried out a more comprehensive in vitro binding assay to substantiate the physical interaction of the channel with these proteins.…”

Section: Resultsmentioning

confidence: 99%

Direct Interaction of Target SNAREs with the Kv2.1 Channel

Michaelevski¹,

Chikvashvili²,

Tsuk³

et al. 2003

Journal of Biological Chemistry

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Previously we suggested that interaction between voltage-gated K ؉ channels and protein components of the exocytotic machinery regulated transmitter release. This study concerns the interaction between the Kv2.1 channel, the prevalent delayed rectifier K ؉ channel in neuroendocrine and endocrine cells, and syntaxin 1A and SNAP-25. We recently showed in islet ␤-cells that the Kv2.1 K ؉ current is modulated by syntaxin 1A and SNAP-25. Here we demonstrate, using co-immunoprecipitation and immunocytochemistry analyses, the existence of a physical interaction in neuroendocrine cells between Kv2.1 and syntaxin 1A. Furthermore, using concomitant co-immunoprecipitation from plasma membranes and two-electrode voltage clamp analyses in Xenopus oocytes combined with in vitro binding analysis, we characterized the effects of these interactions on the Kv2.1 channel gating pertaining to the assembly/disassembly of the syntaxin 1A/SNAP-25 (target (t)-SNARE) complex. Syntaxin 1A alone binds strongly to Kv2.1 and shifts both activation and inactivation to hyperpolarized potentials. SNAP-25 alone binds weakly to Kv2.1 and probably has no effect by itself. Expression of SNAP-25 together with syntaxin 1A results in the formation of t-SNARE complexes, with consequent elimination of the effects of syntaxin 1A alone on both activation and inactivation. Moreover, inactivation is shifted to the opposite direction, toward depolarized potentials, and its extent and rate are attenuated. Based on these results we suggest that exocytosis in neuroendocrine cells is tuned by the dynamic coupling of the Kv2.1 channel gating to the assembly status of the t-SNARE complex.The soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) 1 proteins syntaxin, SNAP-25, and VAMP are crucial factors in processes of transmitter and hormone release (1). They interact with a wide range of proteins, some of them (such as synaptotagmin) associated with vesicular membranes or with plasma membranes (for example, voltage-gated Ca 2ϩ channels) (1-5). We suggested previously (6) that SNARE proteins interact with a member of the Kv1 subfamily of the voltage-gated K ϩ (Kv) channels and that these interactions may play a role in synaptic efficacy and neuronal excitability. Our results showed that in brain synaptosomes the presynaptic Kv1.1 channel (7) interacts with some of the protein components of the exocytotic apparatus, including syntaxin 1A, SNAP-25, and synaptotagmin, in a manner that is sensitive to the exocytotic state of the synaptosomes. We also showed that Kv1.1 in complex with the auxiliary Kv␤ 1.1 subunits (8) interacts directly with syntaxin 1A, and the feedback effect of this interaction on the channel function enhances its fast inactivation in Xenopus oocytes. Involvement of G protein ␤␥ subunits was found to be a requirement for this interaction (9). These characteristics of the interaction of presynaptic Kv channels with syntaxin 1A are reminiscent of the interaction of the presynaptic N-type voltage-gated Ca 2ϩ channels (10 -12)....

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Syntaxin 1A Binds to the Cytoplasmic C Terminus of Kv2.1 to Regulate Channel Gating and Trafficking

Cited by 118 publications

References 26 publications

Apoptotic surface delivery of K+ channels

Apoptotic surface delivery of K+ channels

Convergent Ca ²⁺ and Zn ²⁺ signaling regulates apoptotic Kv2.1 K ⁺ currents

Direct Interaction of Target SNAREs with the Kv2.1 Channel

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Syntaxin 1A Binds to the Cytoplasmic C Terminus of Kv2.1 to Regulate Channel Gating and Trafficking

Cited by 118 publications

References 26 publications

Apoptotic surface delivery of K+ channels

Apoptotic surface delivery of K+ channels

Convergent Ca 2+ and Zn 2+ signaling regulates apoptotic Kv2.1 K + currents

Direct Interaction of Target SNAREs with the Kv2.1 Channel

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Convergent Ca ²⁺ and Zn ²⁺ signaling regulates apoptotic Kv2.1 K ⁺ currents