Immunolocalization of the Ca2+-activated K+ channel Slo1 in axons and nerve terminals of mammalian brain and cultured neurons.
Ca(2+)-activated voltage-dependent K(+) channels (Slo1, KCa1.1, Maxi-K, or BK channel) play a crucial role in controlling neuronal signaling by coupling channel activity to both membrane depolarization and intracellular Ca(2+) signaling. In mammalian brain, immunolabeling experiments have shown staining for Slo1 channels predominantly localized to axons and presynaptic terminals of neurons. We have developed anti-Slo1 mouse monoclonal antibodies that have been extensively characterized for specificity of staining against recombinant Slo1 in heterologous cells, and native Slo1 in mammalian brain, and definitively by the lack of detectable immunoreactivity against brain samples from Slo1 knockout mice. Here we provide precise immunolocalization of Slo1 in rat brain with one of these monoclonal antibodies and show that Slo1 is accumulated in axons and synaptic terminal zones associated with glutamatergic synapses in hippocampus and GABAergic synapses in cerebellum. By using cultured hippocampal pyramidal neurons as a model system, we show that heterologously expressed Slo1 is initially targeted to the axonal surface membrane, and with further development in culture, become localized in presynaptic terminals. These studies provide new insights into the polarized localization of Slo1 channels in mammalian central neurons and provide further evidence for a key role in regulating neurotransmitter release in glutamatergic and GABAergic terminals.
Misonou
Hiroaki
H
Department of Pharmacology, School of Medicine, University of California, Davis, 95616, USA.
Menegola
Milena
M
Buchwalder
Lynn
L
Park
Eunice W
EW
Meredith
Andrea
A
Rhodes
Kenneth J
KJ
Aldrich
Richard W
RW
Trimmer
James S
JS
D000818:Animals; D000831:Animals, Newborn; D001369:Axons / Q000378:metabolism*; D015153:Blotting, Western / Q000379:methods; D001921:Brain / Q000166:cytology* / Q000378:metabolism*; D064026:Calbindins; D002478:Cells, Cultured; D000076122:Disks Large Homolog 4 Protein; D004622:Embryo, Mammalian; D051528:Guanylate Kinases; D007150:Immunohistochemistry / Q000379:methods; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D051665:Kv1.4 Potassium Channel / Q000378:metabolism; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000172:deficiency / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009411:Nerve Endings / Q000378:metabolism*; D016900:Neurofilament Proteins / Q000378:metabolism; D009474:Neurons / Q000166:cytology*; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D051381:Rats; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D051669:Shab Potassium Channels / Q000378:metabolism; D016704:Synapsins / Q000378:metabolism; D016875:tau Proteins / Q000378:metabolism
D064026:Calbindins; D000076122:Disks Large Homolog 4 Protein; C501447:Dlg4 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D051665:Kv1.4 Potassium Channel; D051036:Large-Conductance Calcium-Activated Potassium Channels; C489787:MAP2 protein, rat; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; C489428:Myc protein, mouse; D016900:Neurofilament Proteins; D016271:Proto-Oncogene Proteins c-myc; D064030:S100 Calcium Binding Protein G; D051669:Shab Potassium Channels; D016704:Synapsins; D016875:tau Proteins; D051528:Guanylate Kinases