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Kvbeta2 potassium channel antibody

RRID:AB_2131373

Antibody ID

AB_2131373

Target Antigen

Kvbeta2 potassium channel null

Proper Citation

(UC Davis/NIH NeuroMab Facility Cat# 75-021, RRID:AB_2131373)

Clonality

monoclonal antibody

Comments

Originating manufacturer of this product. Applications: IB, ICC, IHC, IP, KO, WB. Validation status: IF or IB (Pass), IB in brain (Pass), IHC in brain (Pass), KO (Pass).

Clone ID

K17/70

Host Organism

mouse

Vendor

UC Davis/NIH NeuroMab Facility Go To Vendor

Cat Num

75-021

mTOR-dependent alterations of Kv1.1 subunit expression in the neuronal subset-specific Pten knockout mouse model of cortical dysplasia with epilepsy.

  • Nguyen LH
  • Sci Rep
  • 2018 Feb 23

Literature context: euromab #75-010, clone K13/31), mouse anti-Kvβ2 (1:1000, Neuromab #75-021, clone K17/70), and rabbit anti-actin (1:5000,


Abstract:

Cortical dysplasia (CD) is a common cause for intractable epilepsy. Hyperactivation of the mechanistic target of rapamycin (mTOR) pathway has been implicated in CD; however, the mechanisms by which mTOR hyperactivation contribute to the epilepsy phenotype remain elusive. Here, we investigated whether constitutive mTOR hyperactivation in the hippocampus is associated with altered voltage-gated ion channel expression in the neuronal subset-specific Pten knockout (NS-Pten KO) mouse model of CD with epilepsy. We found that the protein levels of Kv1.1, but not Kv1.2, Kv1.4, or Kvβ2, potassium channel subunits were increased, along with altered Kv1.1 distribution, within the hippocampus of NS-Pten KO mice. The aberrant Kv1.1 protein levels were present in young adult (≥postnatal week 6) but not juvenile (≤postnatal week 4) NS-Pten KO mice. No changes in hippocampal Kv1.1 mRNA levels were found between NS-Pten KO and WT mice. Interestingly, mTOR inhibition with rapamycin treatment at early and late stages of the pathology normalized Kv1.1 protein levels in NS-Pten KO mice to WT levels. Together, these studies demonstrate altered Kv1.1 protein expression in association with mTOR hyperactivation in NS-Pten KO mice and suggest a role for mTOR signaling in the modulation of voltage-gated ion channel expression in this model.

Funding information:
  • NIAID NIH HHS - R01AI067979(United States)
  • NICHD NIH HHS - U54 HD083092()
  • NINDS NIH HHS - R01 NS081053()

Cellular mechanisms and behavioral consequences of Kv1.2 regulation in the rat cerebellum.

  • Williams MR
  • J. Neurosci.
  • 2012 Jul 4

Literature context:


Abstract:

The potassium channel Kv1.2 α-subunit is expressed in cerebellar Purkinje cell (PC) dendrites where its pharmacological inhibition increases excitability (Khavandgar et al., 2005). Kv1.2 is also expressed in cerebellar basket cell (BC) axon terminals (Sheng et al., 1994), where its blockade increases BC inhibition of PCs (Southan and Robertson, 1998a). Secretin receptors are also expressed both in PC dendrites and BC axon terminals (for review, see (Yuan et al., 2011). The effect of secretin on PC excitability is not yet known, but, like Kv1.2 inhibitors, secretin potently increases inhibitory input to PCs (Yung et al., 2001). This suggests secretin may act in part by suppressing Kv1.2. Receptor-mediated endocytosis is a mechanism of Kv1.2 suppression (Nesti et al., 2004). This process can be regulated by protein kinase A (PKA) (Connors et al., 2008). Since secretin receptors activate PKA (Wessels-Reiker et al., 1993), we tested the hypothesis that secretin regulates Kv1.2 trafficking in the cerebellum. Using cell-surface protein biotinylation of rat cerebellar slices, we found secretin decreased cell-surface Kv1.2 levels by modulating Kv1.2 endocytic trafficking. This effect was mimicked by activating adenylate cyclase (AC) with forskolin, and was blocked by pharmacological inhibitors of AC or PKA. Imaging studies identified the BC axon terminal and PC dendrites as loci of AC-dependent Kv1.2 trafficking. The physiological significance of secretin-regulated Kv1.2 endocytosis is supported by our finding that infusion into the cerebellar cortex of either the Kv1.2 inhibitor tityustoxin-Kα, or of the Kv1.2 regulator secretin, significantly enhances acquisition of eyeblink conditioning in rats.

Funding information:
  • NINDS NIH HHS - R01 NS015547(United States)

Interactions between the C-terminus of Kv1.5 and Kvβ regulate pyridine nucleotide-dependent changes in channel gating.

  • Tipparaju SM
  • Pflugers Arch.
  • 2012 Jun 14

Literature context:


Abstract:

Voltage-gated potassium (Kv) channels are tetrameric assemblies of transmembrane Kv proteins with cytosolic N- and C-termini. The N-terminal domain of Kv1 proteins binds to β-subunits, but the role of the C-terminus is less clear. Therefore, we studied the role of the C-terminus in regulating Kv1.5 channel and its interactions with Kvβ-subunits. When expressed in COS-7 cells, deletion of the C-terminal domain of Kv1.5 did not affect channel gating or kinetics. Coexpression of Kv1.5 with Kvβ3 increased current inactivation, whereas Kvβ2 caused a hyperpolarizing shift in the voltage dependence of current activation. Inclusion of NADPH in the patch pipette solution accelerated the inactivation of Kv1.5-Kvβ3 currents. In contrast, NADP(+) decreased the rate and the extent of Kvβ3-induced inactivation and reversed the hyperpolarizing shift in the voltage dependence of activation induced by Kvβ2. Currents generated by Kv1.5ΔC+Kvβ3 or Kv1.5ΔC+Kvβ2 complexes did not respond to changes in intracellular pyridine nucleotide concentration, indicating that the C-terminus is required for pyridine nucleotide-dependent interactions between Kvβ and Kv1.5. A glutathione-S-transferase (GST) fusion protein containing the C-terminal peptide of Kv1.5 did not bind to apoKvβ2, but displayed higher affinity for Kvβ2:NADPH than Kvβ2:NADP(+). The GST fusion protein also precipitated Kvβ proteins from mouse brain lysates. Pull-down experiments, structural analysis and electrophysiological data indicated that a specific region of the C-terminus (Arg543-Val583) is required for Kvβ binding. These results suggest that the C-terminal domain of Kv1.5 interacts with β-subunits and that this interaction is essential for the differential regulation of Kv currents by oxidized and reduced nucleotides.

Funding information:
  • NINDS NIH HHS - NS050792(United States)

Characterization of the axon initial segment (AIS) of motor neurons and identification of a para-AIS and a juxtapara-AIS, organized by protein 4.1B.

  • Duflocq A
  • BMC Biol.
  • 2011 Sep 29

Literature context:


Abstract:

BACKGROUND: The axon initial segment (AIS) plays a crucial role: it is the site where neurons initiate their electrical outputs. Its composition in terms of voltage-gated sodium (Nav) and voltage-gated potassium (Kv) channels, as well as its length and localization determine the neuron's spiking properties. Some neurons are able to modulate their AIS length or distance from the soma in order to adapt their excitability properties to their activity level. It is therefore crucial to characterize all these parameters and determine where the myelin sheath begins in order to assess a neuron's excitability properties and ability to display such plasticity mechanisms. If the myelin sheath starts immediately after the AIS, another question then arises as to how would the axon be organized at its first myelin attachment site; since AISs are different from nodes of Ranvier, would this particular axonal region resemble a hemi-node of Ranvier? RESULTS: We have characterized the AIS of mouse somatic motor neurons. In addition to constant determinants of excitability properties, we found heterogeneities, in terms of AIS localization and Nav composition. We also identified in all α motor neurons a hemi-node-type organization, with a contactin-associated protein (Caspr)+ paranode-type, as well as a Caspr2+ and Kv1+ juxtaparanode-type compartment, referred to as a para-AIS and a juxtapara (JXP)-AIS, adjacent to the AIS, where the myelin sheath begins. We found that Kv1 channels appear in the AIS, para-AIS and JXP-AIS concomitantly with myelination and are progressively excluded from the para-AIS. Their expression in the AIS and JXP-AIS is independent from transient axonal glycoprotein-1 (TAG-1)/Caspr2, in contrast to juxtaparanodes, and independent from PSD-93. Data from mice lacking the cytoskeletal linker protein 4.1B show that this protein is necessary to form the Caspr+ para-AIS barrier, ensuring the compartmentalization of Kv1 channels and the segregation of the AIS, para-AIS and JXP-AIS. CONCLUSIONS: α Motor neurons have heterogeneous AISs, which underlie different spiking properties. However, they all have a para-AIS and a JXP-AIS contiguous to their AIS, where the myelin sheath begins, which might limit some AIS plasticity. Protein 4.1B plays a key role in ensuring the proper molecular compartmentalization of this hemi-node-type region.

Funding information:
  • NCI NIH HHS - CA173903(United States)
  • NIGMS NIH HHS - 2R01 GM063891(United States)

Clustering and activity tuning of Kv1 channels in myelinated hippocampal axons.

  • Gu C
  • J. Biol. Chem.
  • 2011 Jul 22

Literature context:


Abstract:

Precise localization of axonal ion channels is crucial for proper electrical and chemical functions of axons. In myelinated axons, Kv1 (Shaker) voltage-gated potassium (Kv) channels are clustered in the juxtaparanodal regions flanking the node of Ranvier. The clustering can be disrupted by deletion of various proteins in mice, including contactin-associated protein-like 2 (Caspr2) and transient axonal glycoprotein-1 (TAG-1), a glycosylphosphatidylinositol-anchored cell adhesion molecule. However, the mechanism and function of Kv1 juxtaparanodal clustering remain unclear. Here, using a new myelin coculture of hippocampal neurons and oligodendrocytes, we report that tyrosine phosphorylation plays a critical role in TAG-1-mediated clustering of axonal Kv1.2 channels. In the coculture, myelin specifically ensheathed axons but not dendrites of hippocampal neurons and clustered endogenous axonal Kv1.2 into internodes. The trans-homophilic interaction of TAG-1 was sufficient to position Kv1.2 clusters on axonal membranes in a neuron/HEK293 coculture. Mutating a tyrosine residue (Tyr⁴⁵⁸) in the Kv1.2 C terminus or blocking tyrosine phosphorylation disrupted myelin- and TAG-1-mediated clustering of axonal Kv1.2. Furthermore, Kv1.2 voltage dependence and activation threshold were reduced by TAG-1 coexpression. This effect was eliminated by the Tyr⁴⁵⁸ mutation or by cholesterol depletion. Taken together, our studies suggest that myelin regulates both trafficking and activity of Kv1 channels along hippocampal axons through TAG-1.

Funding information:
  • NHGRI NIH HHS - R01HG004517(United States)

Cortactin is required for N-cadherin regulation of Kv1.5 channel function.

  • Cheng L
  • J. Biol. Chem.
  • 2011 Jun 10

Literature context:


Abstract:

The intercalated disc serves as an organizing center for various cell surface components at the termini of the cardiomyocyte, thus ensuring proper mechanoelectrical coupling throughout the myocardium. The cell adhesion molecule, N-cadherin, is an essential component of the intercalated disc. Cardiac-specific deletion of N-cadherin leads to abnormal electrical conduction and sudden arrhythmic death in mice. The mechanisms linking the loss of N-cadherin in the heart and spontaneous malignant ventricular arrhythmias are poorly understood. To investigate whether ion channel remodeling contributes to arrhythmogenesis in N-cadherin conditional knock-out (N-cad CKO) mice, cardiac myocyte excitability and voltage-gated potassium channel (Kv), as well as inwardly rectifying K(+) channel remodeling, were investigated in N-cad CKO cardiomyocytes by whole cell patch clamp recordings. Action potential duration was prolonged in N-cad CKO ventricle myocytes compared with wild type. Relative to wild type, I(K,slow) density was significantly reduced consistent with decreased expression of Kv1.5 and Kv accessory protein, Kcne2, in the N-cad CKO myocytes. The decreased Kv1.5/Kcne2 expression correlated with disruption of the actin cytoskeleton and reduced cortactin at the sarcolemma. Biochemical experiments revealed that cortactin co-immunoprecipitates with Kv1.5. Finally, cortactin was required for N-cadherin-mediated enhancement of Kv1.5 channel activity in a heterologous expression system. Our results demonstrate a novel mechanistic link among the cell adhesion molecule, N-cadherin, the actin-binding scaffold protein, cortactin, and Kv channel remodeling in the heart. These data suggest that in addition to gap junction remodeling, aberrant Kv1.5 channel function contributes to the arrhythmogenic phenotype in N-cad CKO mice.

Funding information:
  • NIAMS NIH HHS - K08 AR055688(United States)

Kv1 potassium channel complexes in vivo require Kvbeta2 subunits in dorsal spinal neurons.

  • Pineda RH
  • J. Neurophysiol.
  • 2008 Oct 13

Literature context:


Abstract:

Whereas Kvbeta2 subunits modulate potassium current properties carried by Kv1 channel complexes in heterologous systems, little is known about the contributions of Kvbeta2 subunits to native potassium channel function. Using antisense approaches and in situ recordings from Xenopus embryo spinal cord neurons, we tested the in vivo roles of Kvbeta2 subunits in modulation of voltage-dependent potassium current (IKv). We focused on 1) two different populations of dorsal spinal neurons that express both Kvbeta2 and Kv1 alpha-subunit genes and 2) the 24- and 48-h developmental period, during which IKv undergoes developmental regulation. At both 24 and 48 h, antisense methods produced efficient knock-down of both Kvbeta2 protein and IKv. At both times, dominant negative suppression of Kv1 channels also eliminated IKv, indicating that Kv1 channels require Kvbeta2 subunits to function in dorsal spinal neurons. Even though Kv1 channels determined the IKv values of both dorsal neuron types, comparisons of their IKv properties revealed important differences at both developmental stages. The latter results support the notion that different Kv1 alpha-subunits and/or posttranslational modifications underlie the IKv values of the two dorsal neuron types. Overall, the results demonstrate that Kvbeta2 subunits function in vivo as obligatory subunits of Kv1 channels in at least two neuron types and two different developmental stages.

Postsynaptic density-93 clusters Kv1 channels at axon initial segments independently of Caspr2.

  • Ogawa Y
  • J. Neurosci.
  • 2008 May 28

Literature context:


Abstract:

Postsynaptic density-93 (PSD-93)/Chapsyn-110 is a PDZ (PSD-95/Discs large/zona occludens-1) domain-containing membrane-associated guanylate kinase (MAGUK) that functions as a scaffold to assemble channels, receptors, and other signaling proteins at cell membranes. PSD-93 is highly enriched at synapses, but mice lacking this protein have no synaptic structural abnormalities, probably because of overlapping expression and redundancy with other MAGUKs. Consequently, the function of PSD-93 is not well understood. Here, we show that PSD-93, but not other MAGUKs, is enriched at the axon initial segment (AIS), where it colocalizes with Kv1.1, Kv1.2, Kv1.4, and Kvbeta2 subunit-containing K(+) channels, Caspr2, and TAG-1 (transient axonal glycoprotein-1). When coexpressed with Kv1 channels in heterologous cells, PSD-93 induces formation of large cell-surface clusters. Knockdown of PSD-93 in cultured hippocampal neurons by RNA interference disrupted Kv1 channel localization at the AIS. Similarly, PSD-93-/- mice failed to cluster Kv1 channels at the AIS of cortical and hippocampal neurons. In contrast, Caspr2, which mediates Kv1 channel clustering at the juxtaparanode, is not required for localization of Kv1 channels at the AIS. These results show PSD-93 mediates AIS accumulation of Kv1 channels independently of Caspr2.

Structural consequences of Kcna1 gene deletion and transfer in the mouse hippocampus.

  • Wenzel HJ
  • Epilepsia
  • 2007 Nov 16

Literature context:


Abstract:

PURPOSE: Mice lacking the Kv1.1 potassium channel alpha subunit encoded by the Kcna1 gene develop recurrent behavioral seizures early in life. We examined the neuropathological consequences of seizure activity in the Kv1.1(-/-) (knock-out) mouse, and explored the effects of injecting a viral vector carrying the deleted Kcna1 gene into hippocampal neurons. METHODS: Morphological techniques were used to assess neuropathological patterns in hippocampus of Kv1.1(-/-) animals. Immunohistochemical and biochemical techniques were used to monitor ion channel expression in Kv1.1(-/-) brain. Both wild-type and knockout mice were injected (bilaterally into hippocampus) with an HSV1 amplicon vector that contained the rat Kcna1 subunit gene and/or the E. coli lacZ reporter gene. Vector-injected mice were examined to determine the extent of neuronal infection. RESULTS: Video/EEG monitoring confirmed interictal abnormalities and seizure occurrence in Kv1.1(-/-) mice. Neuropathological assessment suggested that hippocampal damage (silver stain) and reorganization (Timm stain) occurred only after animals had exhibited severe prolonged seizures (status epilepticus). Ablation of Kcna1 did not result in compensatory changes in expression levels of other related ion channel subunits. Vector injection resulted in infection primarily of granule cells in hippocampus, but the number of infected neurons was quite variable across subjects. Kcna1 immunocytochemistry showed "ectopic" Kv1.1 alpha channel subunit expression. CONCLUSIONS: Kcna1 deletion in mice results in a seizure disorder that resembles--electrographically and neuropathologically--the patterns seen in rodent models of temporal lobe epilepsy. HSV1 vector-mediated gene transfer into hippocampus yielded variable neuronal infection.

Funding information:
  • NIMH NIH HHS - R01 MH084812(United States)