Expression of Kv1 potassium channels in mouse hippocampal primary cultures: development and activity-dependent regulation.
Excitability and discharge behavior of neurons depends on the highly variable expression pattern of voltage-dependent potassium (Kv) channels throughout the nervous system. To learn more about distribution, development, and activity-dependent regulation of Kv channel subunit expression in the rodent hippocampus, we studied the protein expression of members of the Kv1 subfamily in mouse hippocampus in situ and in primary cultures. In adult hippocampus, Kv1 (1-6) channel alpha-subunits were present, whereas at postnatal day 2, none of these proteins could be detected in CA1-CA3 and dentate gyrus. Kv1.1 was the first channel to be observed at postnatal day 6. The delayed postnatal expression and most of the subcellular distribution observed in hippocampal sections were mimicked by cultured hippocampal neurons in which Kv channels appeared only after 10 days in vitro. This developmental upregulation was paralleled by a dramatic increase in total K(+) current, as well as an elevated GABA release in the presence of 4-aminopyridine. Thus, the developmental profile, subcellular localization, and functionality of Kv1 channels in primary culture of hippocampus closely resembles the in situ situation. Impairing secretion by clostridial neurotoxins or blocking activity by tetrodotoxin inhibited the expression of Kv1.1, Kv1.2, and Kv1.4, whereas the other Kv1 channels still appeared. This activity-dependent depression was only observed before the initial appearance of the respective channels and lost after they had been expressed. Our data show that hippocampal neurons in culture are a convenient model to study the developmental expression and regulation of Kv1 channels. The ontogenetic regulation and the activity-dependent expression of Kv1.1, Kv1.2, and Kv1.4 indicate that neuronal activity plays a crucial role for the development of the mature Kv channel pattern in hippocampal neurons.
Grosse
G
G
Institut für Anatomie der Charité, Humboldt-Universität zu Berlin, 10115 Berlin, Germany.
Draguhn
A
A
Höhne
L
L
Tapp
R
R
Veh
R W
RW
Ahnert-Hilger
G
G
D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D001369:Axons / Q000737:chemistry / Q000502:physiology; D019274:Botulinum Toxins, Type A / Q000494:pharmacology; D002478:Cells, Cultured; D051668:Delayed Rectifier Potassium Channels; D018891:Dentate Gyrus / Q000166:cytology* / Q000196:embryology; D005333:Fetus / Q000166:cytology; D051662:Kv1.1 Potassium Channel; D051663:Kv1.2 Potassium Channel; D051664:Kv1.3 Potassium Channel; D051665:Kv1.4 Potassium Channel; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008565:Membrane Proteins / Q000032:analysis; D051379:Mice; D008815:Mice, Inbred Strains; D008854:Microscopy, Electron; D009419:Nerve Tissue Proteins / Q000032:analysis; D009457:Neuroglia / Q000737:chemistry; D009465:Neuromuscular Agents / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000032:analysis* / Q000096:biosynthesis* / Q000502:physiology; D024642:Potassium Channels, Voltage-Gated; D017966:Pyramidal Cells / Q000737:chemistry* / Q000502:physiology / Q000648:ultrastructure; D050683:R-SNARE Proteins; D050825:Synaptosomal-Associated Protein 25; D013744:Tetanus Toxin / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D051668:Delayed Rectifier Potassium Channels; C496947:Kcna1 protein, mouse; C496970:Kcna2 protein, mouse; C496974:Kcna3 protein, mouse; C496978:Kcna4 protein, mouse; D051663:Kv1.2 Potassium Channel; D051664:Kv1.3 Potassium Channel; D051665:Kv1.4 Potassium Channel; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D009465:Neuromuscular Agents; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D050683:R-SNARE Proteins; C494209:Snap25 protein, mouse; D050825:Synaptosomal-Associated Protein 25; D013744:Tetanus Toxin; D051662:Kv1.1 Potassium Channel; D013779:Tetrodotoxin; D005680:gamma-Aminobutyric Acid; D015761:4-Aminopyridine; D019274:Botulinum Toxins, Type A