Differential subcellular localization of SK3‐containing channels in the hippocampus

Small‐conductance, Ca2+‐activated K+ (SK) channels are expressed in the hippocampus where they regulate synaptic responses, plasticity, and learning and memory. To investigate the expression of SK3 (KCNN3) subunits, we determined the developmental profile and subcellular distribution of SK3 in the developing mouse hippocampus using western blots, immunohistochemistry and high‐resolution immunoelectron microscopy. The results showed that SK3 expression increased during postnatal development, and that the localization of SK3 changed from being mainly associated with the endoplasmic reticulum and intracellular sites during the first postnatal week to being progressively concentrated in dendritic spines during later stages. In the adult, SK3 was localized mainly in postsynaptic compartments, both at extrasynaptic sites and along the postsynaptic density of excitatory synapses. Double labelling showed that SK3 co‐localized with SK2 (KCNN2) and with N‐methyl‐D‐aspartate receptors. Finally, quantitative analysis of SK3 density revealed two subcellular distribution patterns in different hippocampal layers, with SK3 being unevenly distributed in CA1 region of the hippocampus pyramidal cells and homogeneously distributed in dentate gyrus granule cells. Our results revealed a complex cell surface distribution of SK3‐containing channels and a distinct developmental program that may influence different hippocampal functions.

[1]  J. Storm,et al.  Regional Differences in Distribution and Functional Expression of Small-Conductance Ca2+-Activated K+ Channels in Rat Brain , 2002, The Journal of Neuroscience.

[2]  R. Luján,et al.  New sites of action for GIRK and SK channels , 2009, Nature Reviews Neuroscience.

[3]  J. Adelman,et al.  Regional distribution of SK3 mRNA‐containing neurons in the adult and adolescent rat ventral midbrain and their relationship to dopamine‐containing cells , 2004, Synapse.

[4]  D. Johnston,et al.  Dendritic ion channelopathy in acquired epilepsy , 2012, Epilepsia.

[5]  Masahiko Watanabe,et al.  SK2 channel plasticity contributes to LTP at Schaffer collateral–CA1 synapses , 2008, Nature Neuroscience.

[6]  M. Kye,et al.  Small-conductance, Ca2+-activated K+ channel SK3 generates age-related memory and LTP deficits , 2003, Nature Neuroscience.

[7]  J. Macdonald,et al.  Nonselective cation channels and links to hippocampal ischemia, aging, and dementia. , 2013, Advances in experimental medicine and biology.

[8]  P. Pedarzani,et al.  An apamin-sensitive Ca2+-activated K+ current in hippocampal pyramidal neurons. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[9]  Rafael Luján,et al.  Disruption of Dopamine Neuron Activity Pattern Regulation through Selective Expression of a Human KCNN3 Mutation , 2013, Neuron.

[10]  Wendy W. Wu,et al.  Developmental profile of SK2 channel expression and function in CA1 neurons , 2012, Hippocampus.

[11]  Max Planck,et al.  An apamin-sensitive Ca 21 -activated K 1 current in hippocampal pyramidal neurons , 1999 .

[12]  R. Shigemoto,et al.  Localization of metabotropic GABA receptor subunits GABAB1 and GABAB2 relative to synaptic sites in the rat developing cerebellum , 2006, The European journal of neuroscience.

[13]  K. Schilling,et al.  An immunoblot assay for the simultaneous quantification of several antigens. , 1989, Analytical biochemistry.

[14]  B. Sabatini,et al.  SK channels and NMDA receptors form a Ca2+-mediated feedback loop in dendritic spines , 2005, Nature Neuroscience.

[15]  G. Lynch,et al.  A Novel Mechanism for the Facilitation of Theta-Induced Long-Term Potentiation by Brain-Derived Neurotrophic Factor , 2004, The Journal of Neuroscience.

[16]  J. T. Williams,et al.  SK2 and SK3 expression differentially affect firing frequency and precision in dopamine neurons , 2012, Neuroscience.

[17]  J. Lacaille,et al.  Kv4.3-Mediated A-Type K+ Currents Underlie Rhythmic Activity in Hippocampal Interneurons , 2007, The Journal of Neuroscience.

[18]  R. Stackman,et al.  Small Conductance Ca2+-Activated K+ Channel Knock-Out Mice Reveal the Identity of Calcium-Dependent Afterhyperpolarization Currents , 2004, The Journal of Neuroscience.

[19]  N. Marrion,et al.  Small-Conductance, Calcium-Activated Potassium Channels from Mammalian Brain , 1996, Science.

[20]  Masahiko Watanabe,et al.  T-type Ca2+ channels, SK2 channels and SERCAs gate sleep-related oscillations in thalamic dendrites , 2008, Nature Neuroscience.

[21]  T. Kosaka,et al.  Postsynaptic and extrasynaptic localization of Kv4.2 channels in the mouse hippocampal region, with special reference to targeted clustering at gabaergic synapses , 2005, Neuroscience.

[22]  N. Marrion,et al.  Crucial role of a shared extracellular loop in apamin sensitivity and maintenance of pore shape of small-conductance calcium-activated potassium (SK) channels , 2011, Proceedings of the National Academy of Sciences.

[23]  Y. Jan,et al.  Presynaptic Localization of Kv1.4-Containing A-Type Potassium Channels Near Excitatory Synapses in the Hippocampus , 1998, The Journal of Neuroscience.

[24]  T. Ishii,et al.  Determinants of Apamin and d-Tubocurarine Block in SK Potassium Channels* , 1997, The Journal of Biological Chemistry.

[25]  Thanos Tzounopoulos,et al.  Small Conductance Ca2+-Activated K+Channels Modulate Synaptic Plasticity and Memory Encoding , 2002, The Journal of Neuroscience.

[26]  J. Marksteiner,et al.  Comparative immunohistochemical distribution of three small-conductance Ca2+-activated potassium channel subunits, SK1, SK2, and SK3 in mouse brain , 2004, Molecular and Cellular Neuroscience.

[27]  Masahiko Watanabe,et al.  The SK2-Long Isoform Directs Synaptic Localization and Function of SK2-containing channels , 2011, Nature Neuroscience.

[28]  P. Pedarzani,et al.  Differential Distribution of Three Ca2+-Activated K+ Channel Subunits, SK1, SK2, and SK3, in the Adult Rat Central Nervous System , 2000, Molecular and Cellular Neuroscience.

[29]  K. Reymann,et al.  Inhibition of apamin-sensitive calcium dependent potassium channels facilitate the induction of long-term potentiation in the CA1 region of rat hippocampus in vitro , 1998, Neuroscience Letters.

[30]  J. Adelman,et al.  Selective cognitive deficits and reduced hippocampal brain-derived neurotrophic factor mRNA expression in small-conductance calcium-activated K+ channel deficient mice , 2009, Neuroscience.

[31]  T. Strassmaier,et al.  A Novel Isoform of SK2 Assembles with Other SK Subunits in Mouse Brain* , 2005, Journal of Biological Chemistry.

[32]  R Lujan,et al.  Perisynaptic Location of Metabotropic Glutamate Receptors mGluR1 and mGluR5 on Dendrites and Dendritic Spines in the Rat Hippocampus , 1996, The European journal of neuroscience.

[33]  Andrea Klug,et al.  The Hippocampus Book , 2016 .

[34]  J. Partridge,et al.  Selective acquisition of AMPA receptors over postnatal development suggests a molecular basis for silent synapses , 1999, Nature Neuroscience.

[35]  Mihaly Kollo,et al.  Novel Subcellular Distribution Pattern of A-Type K+ Channels on Neuronal Surface , 2006, The Journal of Neuroscience.

[36]  R. Shigemoto,et al.  Quantitative analysis and subcellular distribution of mRNA and protein expression of the hyperpolarization-activated cyclic nucleotide-gated channels throughout development in rat , 2011 .

[37]  A. Fairén,et al.  Differential distribution of group I metabotropic glutamate receptors during rat cortical development. , 2002, Cerebral cortex.

[38]  Masahiko Watanabe,et al.  Input-Specific Intrasynaptic Arrangements of Ionotropic Glutamate Receptors and Their Impact on Postsynaptic Responses , 2009, The Journal of Neuroscience.

[39]  J. Adelman,et al.  SK channels in excitability, pacemaking and synaptic integration , 2005, Current Opinion in Neurobiology.

[40]  J. Adelman,et al.  Immunocytochemical localization of small‐conductance, calcium‐dependent potassium channels in astrocytes of the rat supraoptic nucleus , 2005, The Journal of comparative neurology.

[41]  Masahiko Watanabe,et al.  Developmental regulation of G protein‐gated inwardly‐rectifying K+ (GIRK/Kir3) channel subunits in the brain , 2011, The European journal of neuroscience.

[42]  G. Terstappen,et al.  Distribution of the messenger RNA for the small conductance calcium-activated potassium channel SK3 in the adult rat brain and correlation with immunoreactivity , 2001, Neuroscience.

[43]  R. Shigemoto,et al.  Cerebral Cortex doi:10.1093/cercor/bhk021 Quantitative Analysis and Subcellular Distribution of mRNA and Protein Expression of the Hyperpolarization- Activated Cyclic Nucleotide-Gated Channels throughout Development in Rat , 2006 .

[44]  K. Fujimoto.  Freeze-fracture replica electron microscopy combined with SDS digestion for cytochemical labeling of integral membrane proteins. Application to the immunogold labeling of intercellular junctional complexes. , 1995, Journal of cell science.