Direct Interaction between the Actin-binding Protein Filamin-A and the Inwardly Rectifying Potassium Channel, Kir2.1

Sampson, Laura J.; Leyland, Mark L.; Dart, Caroline

doi:10.1074/jbc.m307479200

Cited by 78 publications

(73 citation statements)

References 41 publications

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“…Kv4.2 is reported to bind via the sequence PTPP (17,31). Although the sequence PXXP is conserved in mHCN1, we found that it is not responsible for the interaction between filamin A and mHCN1.…”

Section: Resultscontrasting

confidence: 55%

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Interaction of the Pacemaker Channel HCN1 with Filamin A

Gravante

Barbuti

Milanesi

et al. 2004

Journal of Biological Chemistry

109

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Pacemaker channels are encoded by the HCN gene family and are responsible for a variety of cellular functions including control of spontaneous activity in cardiac myocytes and control of excitability in different types of neurons. Some of these functions require specific membrane localization. Although several voltagegated channels are known to interact with intracellular proteins exerting auxiliary functions, no cytoplasmic proteins have been found so far to modulate HCN channels. Through the use of a yeast two-hybrid technique, here we showed that filamin A interacts with HCN1, an HCN isoform widely expressed in the brain, but not with HCN2 or HCN4. Filamin A is a cytoplasmic scaffold protein with actin-binding domains whose main function is to link transmembrane proteins to the actin cytoskeleton. Using several HCN1 C-terminal constructs, we identified a filamin A-interacting region of 22 amino acids located downstream from the cyclic nucleotide-binding domain; this region is not conserved in HCN2, HCN3, or HCN4. We also verified by immunoprecipitation from bovine brain that the filamin A-HCN1 interaction is functional in vivo. In filamin A-expressing cells (filamin ؉ ), HCN1 (but not HCN4) channels were expressed in hot spots, whereas they were evenly distributed on the membrane of cells lacking filamin A (filamin ؊ ) indicating that interaction with filamin A affects membrane localization. Also, in filamin ؊ cells the gating kinetics of HCN1 were strongly accelerated relative to filamin ؉ cells. The interaction with filamin A may contribute to localizing HCN1 channels to specific neuronal areas and to modulating channel activity.

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Section: Resultscontrasting

confidence: 55%

“…For example, it is known that several KCNQ channel isoforms interact with the ␤-subunits KCNE1 or KCNE2 to generate currents similar to those recorded in native tissue (30). Also, Kv1 channels interact with PSD95, whereas Kv4.2 and Kir2.1 channels have been reported to link to filamin A (17,18,31).…”

Section: Resultsmentioning

confidence: 99%

Interaction of the Pacemaker Channel HCN1 with Filamin A

Gravante

Barbuti

Milanesi

et al. 2004

Journal of Biological Chemistry

109

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“…The interaction with actin cytoskeleton through filamin-A may regulate location of the channel at the cell surface as well as the oligomerization state and stability. Cells that lack filamin-A have reduced whole-cell Kir2.1 currents, but filamin-A has no significant effect on single channel amplitude or open probability, suggesting a reduced number of functional channels in the cell membrane (42). We noted that Kir 2.1-Ab application in vivo reduced the STR and PhNR amplitudes maximally only by about half, which suggests that antibody attachment near the C terminus PDZ binding motif may similarly interrupt channel binding to cytoskeleton and reduce the number of functional channels.…”

Section: Discussionmentioning

confidence: 99%

“…Channel interaction with the cytoskeleton is regulated through a PSD-95 complex via a type-I PDZ binding motif (41,42). The interaction with actin cytoskeleton through filamin-A may regulate location of the channel at the cell surface as well as the oligomerization state and stability.…”

Section: Discussionmentioning

confidence: 99%

Probing potassium channel function in vivo by intracellular delivery of antibodies in a rat model of retinal neurodegeneration

Raz-Prag

Grimes

Fariss³

et al. 2010

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

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Inward rectifying potassium (Kir) channels participate in regulating potassium concentration (K + ) in the central nervous system (CNS), including in the retina. We explored the contribution of Kir channels to retinal function by delivering Kir antibodies (Kir-Abs) into the rat eye in vivo to interrupt channel activity. Kir-Abs were coupled to a peptide carrier to reach intracellular epitopes. Functional effects were evaluated by recording the scotopic threshold response (STR) and photopic negative response (PhNR) of the electroretinogram (ERG) noninvasively with an electrode on the cornea to determine activity of the rod and cone pathways, respectively. Intravitreal delivery of Kir2.1-Ab coupled to the peptide carrier diminished these ERG responses equivalent to dimming the stimulus 10-to 100-fold. Immunohistochemistry (IHC) showed Kir2.1 immunostaining of retinal bipolar cells (BCs) matching the labeling pattern obtained with conventional IHC of applying Kir2.1-Ab to fixed retinal sections postmortem. Whole-cell voltage-clamp BC recordings in rat acute retinal slices showed suppression of bariumsensitive Kir2.1 currents upon inclusion of Kir2.1-Ab in the patch pipette. The in vivo functional and structural results implicate a contribution of Kir2.1 channel activity in these electronegative ERG potentials. Studies with Kir4.1-Ab administered in vivo also suppressed the ERG components and showed immunostaining of Müller cells. The strategy of administering Kir antibodies in vivo, coupled to a peptide carrier to facilitate intracellular delivery, identifies roles for Kir2.1 and Kir4.1 in ERG components arising in the proximal retina and suggests this approach could be of further value in research.Kir | peptide carrier | Pep-1 | retinal bipolar cells | Müller cells

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“…Similarly Kv1.4 potassium channels undergo constitutive internalization unless it is stabilized by co-expression with the scaffolding protein PSD-95 (36,37). Membrane stability of ligand-gated channels might also be promoted by interactions with intracellular proteins that regulate membrane turnover and degradation of the receptor.…”

Section: Discussionmentioning

confidence: 99%

Identification of a Trafficking Motif Involved in the Stabilization and Polarization of P2X Receptors

Chaumont

Jiang

Penna

et al. 2004

Journal of Biological Chemistry

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Extracellular ATP-gated channels (P2X receptors) define the third major family of ionotropic receptors, and they are expressed widely in nerve cells, muscles, and endocrine and exocrine glands. P2X subunits have two membrane-spanning domains, and a receptor is thought to be formed by oligomerization of three subunits. We have identified a conserved motif in the cytoplasmic C termini of P2X subunits that is necessary for their surface expression; mutations in this motif result in a marked reduction of the receptors at the plasma membrane because of a rapid internalization. Transfer of the motif to a reporter protein (CD 4 ) enhances the surface expression of the chimera, indicating that this motif is likely involved in the stabilization of P2X receptor at the cell surface. In neurons, mutated P2X 2 subunits showed reduced membrane expression and an altered axodendritic distribution. This motif is also present in intracellular regions of other membrane proteins, such as in the third intracellular loop of some G protein-coupled receptors, suggesting that it might be involve in their cellular stabilization and polarization.P2X receptors are extracellular ATP-gated ion channels; they define the third major class of ligand-gated channels together with the glutamate and the nicotinic superfamilies (1). P2X receptors are involved in synaptic transmission in the central and peripheral nervous systems, but in contrast to other ligand-gated channels, they are also widely expressed in peripheral tissues where they participate in physiological processes as diverse as smooth muscle contraction, secretion, and bone resorption. ATP-induced currents have been recorded from a large number of different cell types (2), but the molecular identity of P2X receptors responsible for these currents often remains elusive because of limitations of pharmacological tools to discriminate the different subtypes of P2X channels.Seven P2X subunit genes (P2X 1 -P2X 7 ) are found in the human genome; this number seems to be an accurate estimation of the extent of the P2X family in mammalian species, although in zebrafish two additional subunits appear to exist (2, 3). The basic structural determinants of P2X channels have been established by numerous molecular studies (4). P2X subunits have a membrane topology with two transmembrane domains linked by a large extracellular loop; N and C termini are localized intracellularly (5, 6). To form a channel, P2X subunits are thought to associate as homo-or heterooligomers, composed of three subunits (7, 8) organized in a head-to-tail orientation around a central pore (9). This model is consistent with studies that show that the permeation pathway is associated with transmembrane regions (10 -12), and with the fact that the gating of the channel is in part due to movements of the subunits relative to the each other (12). Conserved charged residues in the extracellular loop have been implicated in ATP binding (13,14), and desensitization is tightly linked to transmembrane domains and intracellular regions lo...

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Direct Interaction between the Actin-binding Protein Filamin-A and the Inwardly Rectifying Potassium Channel, Kir2.1

Cited by 78 publications

References 41 publications

Interaction of the Pacemaker Channel HCN1 with Filamin A

Interaction of the Pacemaker Channel HCN1 with Filamin A

Probing potassium channel function in vivo by intracellular delivery of antibodies in a rat model of retinal neurodegeneration

Identification of a Trafficking Motif Involved in the Stabilization and Polarization of P2X Receptors

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