TY - JOUR
T1 - Activation of KCNN3/SK3/KCa2.3 channels attenuates enhanced calcium influx and inflammatory cytokine production in activated microglia
AU - Dolga, Amalia M.
AU - Letsche, Till
AU - Gold, Maike
AU - Doti, Nunzianna
AU - Bacher, Michael
AU - Chiamvimonvat, Nipavan
AU - Dodel, Richard
AU - Culmsee, Carsten
PY - 2012/12
Y1 - 2012/12
N2 - In neurons, small-conductance calcium-activated potassium (KCNN/SK/KCa2) channels maintain calcium homeostasis after N-methyl-D-aspartate (NMDA) receptor activation, thereby preventing excitotoxic neuronal death. So far, little is known about the function of KCNN/SK/KCa2 channels in non-neuronal cells, such as microglial cells. In this study, we addressed the question whether KCNN/SK/KCa2 channels activation affected inflammatory responses of primary mouse microglial cells upon lipopolysaccharide (LPS) stimulation. We found that N-cyclohexyl-N-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-4-pyrimidinamine (CyPPA), a positive pharmacological activator of KCNN/SK/KCa2 channels, significantly reduced LPS-stimulated activation of microglia in a concentration-dependent manner. The general KCNN/SK/KCa2 channel blocker apamin reverted these effects of CyPPA on microglial proliferation. Since calcium plays a central role in microglial activation, we further addressed whether KCNN/SK/KCa2 channel activation affected the changes of intracellular calcium levels, [Ca2+]i,, in microglial cells. Our data show that LPS-induced elevation of [Ca2+]i was attenuated following activation of KCNN2/3/KCa2.2/KCa2.3 channels by CyPPA. Furthermore, CyPPA reduced downstream events including tumor necrosis factor alpha and interleukin 6 cytokine production and nitric oxide release in activated microglia. Further, we applied specific peptide inhibitors of the KCNN/SK/KCa2 channel subtypes to identify which particular channel subtype mediated the observed anti-inflammatory effects. Only inhibitory peptides targeting KCNN3/SK3/KCa2.3 channels, but not KCNN2/SK2/KCa2.2 channel inhibition, reversed the CyPPA-effects on LPS-induced microglial proliferation. These findings revealed that KCNN3/SK3/KCa2.3 channels can modulate the LPS-induced inflammatory responses in microglial cells. Thus, KCNN3/SK3/KCa2.3 channels may serve as a therapeutic target for reducing microglial activity and related inflammatory responses in the central nervous system.
AB - In neurons, small-conductance calcium-activated potassium (KCNN/SK/KCa2) channels maintain calcium homeostasis after N-methyl-D-aspartate (NMDA) receptor activation, thereby preventing excitotoxic neuronal death. So far, little is known about the function of KCNN/SK/KCa2 channels in non-neuronal cells, such as microglial cells. In this study, we addressed the question whether KCNN/SK/KCa2 channels activation affected inflammatory responses of primary mouse microglial cells upon lipopolysaccharide (LPS) stimulation. We found that N-cyclohexyl-N-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-4-pyrimidinamine (CyPPA), a positive pharmacological activator of KCNN/SK/KCa2 channels, significantly reduced LPS-stimulated activation of microglia in a concentration-dependent manner. The general KCNN/SK/KCa2 channel blocker apamin reverted these effects of CyPPA on microglial proliferation. Since calcium plays a central role in microglial activation, we further addressed whether KCNN/SK/KCa2 channel activation affected the changes of intracellular calcium levels, [Ca2+]i,, in microglial cells. Our data show that LPS-induced elevation of [Ca2+]i was attenuated following activation of KCNN2/3/KCa2.2/KCa2.3 channels by CyPPA. Furthermore, CyPPA reduced downstream events including tumor necrosis factor alpha and interleukin 6 cytokine production and nitric oxide release in activated microglia. Further, we applied specific peptide inhibitors of the KCNN/SK/KCa2 channel subtypes to identify which particular channel subtype mediated the observed anti-inflammatory effects. Only inhibitory peptides targeting KCNN3/SK3/KCa2.3 channels, but not KCNN2/SK2/KCa2.2 channel inhibition, reversed the CyPPA-effects on LPS-induced microglial proliferation. These findings revealed that KCNN3/SK3/KCa2.3 channels can modulate the LPS-induced inflammatory responses in microglial cells. Thus, KCNN3/SK3/KCa2.3 channels may serve as a therapeutic target for reducing microglial activity and related inflammatory responses in the central nervous system.
KW - Calcium homeostasis
KW - CyPPA
KW - Cytokines
KW - Microglia
KW - Potassium KCNN/SK/K2 channels
UR - http://www.scopus.com/inward/record.url?scp=84867647374&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84867647374&partnerID=8YFLogxK
U2 - 10.1002/glia.22419
DO - 10.1002/glia.22419
M3 - Article
C2 - 23002008
AN - SCOPUS:84867647374
VL - 60
SP - 2050
EP - 2064
JO - GLIA
JF - GLIA
SN - 0894-1491
IS - 12
ER -