title: Expression of the voltage- and Ca2+-dependent BK potassium channel subunits BKβ1 and BKβ4 in rodent astrocytes.
abstract: Large-conductance Ca(2+) -activated (BK) potassium channels are centrally involved in neurovascular coupling, immunity, and neural transmission. The ability to be synergistically activated by membrane depolarization, different ligands and intracellular Ca(2+) links intracellular signaling and membrane excitability. The diverse physiological functions of BK channels crucially depend on regulatory β subunits. Although first studies characterized the neuronal distribution of BKβ subunits in the rodent brain, it is largely unknown which β subunit proteins are expressed in astrocytes and thus mediate these regulatory effects. We therefore analyzed the expression of BKβ subunits in rat and mouse brain and glial cell cultures. A monospecific polyclonal antibody against the BKβ4 channel subunit was raised, affinity-purified and extensively characterized. BKβ4 and to a lesser degree BKβ1 transcripts and protein were detected in several astrocytic populations and cultured cells. Particularly strong BKβ4 immunostaining was detected in astrocytic progenitors derived from the subventricular zone. The overlapping expression of BKα and BKβ4 in astrocytes implies a functional relationship and suggests that BKβ4 is an important accessory β subunit for astrocytic BK channels. In addition, BKβ4 might exert effects independent of the α subunit as functional heterologous co-expression of Nav1.6 and BKβ4 resulted in reduced Nav1.6 sodium currents. Thus, BKβ4 expression in astrocytes likely participates in regulating astrocytic voltage gradients and maintaining K(+) homeostasis, hence enabling astrocytes to fulfill their complex regulatory influence on proper brain function.
authors: Institute for Integrative Neuroanatomy, Charité University Medicine Berlin, 10115 Berlin, Germany.
authors: Katharina N
authors: KN
authors: Seidel
authors: Christian
authors: C
authors: Derst
authors: Mikhail
authors: M
authors: Salzmann
authors: Markus
authors: M
authors: Höltje
authors: Josef
authors: J
authors: Priller
authors: René
authors: R
authors: Markgraf
authors: Stefan H
authors: SH
authors: Heinemann
authors: Heike
authors: H
authors: Heilmann
authors: Serguei N
authors: SN
authors: Skatchkov
authors: Misty J
authors: MJ
authors: Eaton
authors: Rüdiger W
authors: RW
authors: Veh
authors: Harald
authors: H
authors: Prüss
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism*; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D016466:CHO Cells; D002478:Cells, Cultured; D006224:Cricetinae; D003412:Cricetulus; D057809:HEK293 Cells; D006706:Homeostasis / Q000235:genetics; D006801:Humans; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009865:Oocytes; D051381:Rats; D017208:Rats, Wistar; D014982:Xenopus laevis
chemical_list: D051036:Large-Conductance Calcium-Activated Potassium Channels