Involvement of batrachotoxin binding sites in ginsenoside-mediated voltage-gated Na+ channel regulation.
Recently, we showed that the 20(S)-ginsenoside Rg3 (Rg3), an active ingredient of Panax ginseng, inhibits rat brain NaV1.2 channel peak currents (INa). Batrachotoxin (BTX) is a steroidal alkaloid neurotoxin and activates NaV channels through interacting with transmembrane domain-I-segment 6 (IS6) of channels. Recent report shows that ginsenoside inhibits BTX binding in rat brain membrane fractions. However, it needs to be confirmed whether biochemical mechanism is relevant physiologically and which residues of the BTX binding sites are important for ginsenoside regulations. Here, we demonstrate that mutations of BTX binding sites such as N418K and L421K of rat brain NaV1.2 and L437K of mouse skeletal muscle NaV1.4 channel reduce or abolish Rg3 inhibition of I(Na) and attenuate Rg3-mediated depolarizing shift of the activation voltage and use-dependent inhibition. These results indicate that BTX binding sites play an important role in modifying Rg3-mediated Na+ channel properties.
Lee
Jun-Ho
JH
Ginsentology Research Laboratory and Department of Physiology, College of Veterinary Medicine, Konkuk University, Seoul Korea, 143-701.
Lee
Byung-Hwan
BH
Choi
Sun-Hye
SH
Yoon
In-Soo
IS
Shin
Tae-Joon
TJ
Pyo
Mi Kyung
MK
Lee
Sang-Mok
SM
Kim
Hyoung-Chun
HC
Nah
Seung-Yeol
SY
D000818:Animals; D001496:Batrachotoxins / Q000737:chemistry / Q000494:pharmacology*; D001665:Binding Sites / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D036145:Ginsenosides / Q000737:chemistry / Q000494:pharmacology*; D015640:Ion Channel Gating / Q000187:drug effects* / Q000502:physiology; D007930:Leucine / Q000235:genetics; D008239:Lysine / Q000235:genetics; D051379:Mice; D008845:Microinjections; D009124:Muscle Proteins / Q000235:genetics / Q000502:physiology*; D018482:Muscle, Skeletal; D062551:NAV1.2 Voltage-Gated Sodium Channel; D009419:Nerve Tissue Proteins; D009498:Neurotoxins / Q000494:pharmacology*; D009865:Oocytes; D018408:Patch-Clamp Techniques; D017354:Point Mutation / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D051381:Rats; D015222:Sodium Channels / Q000235:genetics / Q000502:physiology*; D014982:Xenopus laevis
D001496:Batrachotoxins; D036145:Ginsenosides; D009124:Muscle Proteins; D062551:NAV1.2 Voltage-Gated Sodium Channel; D009419:Nerve Tissue Proteins; D009498:Neurotoxins; C568253:Scn2A protein, rat; C000654500:Scn2a protein, mouse; C466180:Scn4a protein, rat; D015222:Sodium Channels; C097367:ginsenoside Rg3; D007930:Leucine; D008239:Lysine