1. Novel effects of extracts from poisonous mushrooms on expression and function of the human ether-a-go-go-related gene channel
- Author
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Sulistiyati-Bayu Utami, Peili Li, Tsuyoshi Ichiyanagi, Ichiro Hisatome, Saki Tanaka, Haruaki Ninomiya, Tadanori Aimi, Junichiro Miake, Yakuang Ting, and Yasuaki Shirayoshi
- Subjects
congenital, hereditary, and neonatal diseases and abnormalities ,Small interfering RNA ,animal structures ,Patch-Clamp Techniques ,hERG ,Pharmaceutical Science ,Action Potentials ,Pharmacology ,Cell Line ,Humans ,HSP70 Heat-Shock Proteins ,cardiovascular diseases ,RNA, Small Interfering ,DNA Primers ,Gene knockdown ,biology ,Base Sequence ,Reverse Transcriptase Polymerase Chain Reaction ,HEK 293 cells ,Cardiac action potential ,General Medicine ,Transfection ,Ether-A-Go-Go Potassium Channels ,Hsp70 ,Reverse transcription polymerase chain reaction ,biology.protein ,Agaricales ,Ion Channel Gating - Abstract
The human ether-a-go-go-related gene (hERG) encodes the α subunit of the potassium current IKr, which plays a pivotal role in cardiac action potential repolarization. Inherited mutations of this gene cause Long QT syndrome type 2. hERG expression is altered by several types of drugs as well as by temperature. Heat shock protein 70 (Hsp70) and Heat shock cognate protein 70 (Hsc70) have reciprocal effects on hERG proteins. We examined the effects of poisonous mushrooms on hERG protein expression and its channel function. Methods: We evaluated the effects of several types of poisonous mushrooms on the expression and function of wild-type hERG by Western blotting, reverse transcription polymerase chain reaction (PCR), and patch clamping in transfected HEK293 cells and mouse HL-1 cardiomyocytes. Results: Extracts of Gymnopilus junonius (junonius) increased expression of both hERG and Hsp70 in HEK293 cells with concomitant decrease in Hsc70, whereas extracts of Amanita ibotengutake (ibotengutake) decreased hERG proteins with increase in Hsc70. Knockdown of Hsp70 and Hsc70 by small interfering RNA abolished the effects of the two mushrooms on hERG, respectively. Certain fractions of junonius increased expression of hERG proteins. hERG currents were increased by extracts of junonius, resulting in shortening of action potential duration (APD). In contrast, hERG currents were decreased and APD was prolonged by extracts of ibotengutake. Conclusion: junonius enhanced the expression and function of hERG by increasing Hsp70 and decreasing Hsc70. Ibotengutake decreased hERG expression via increase in Hsc70. Constituents of junonius may have the potential for use in treatment of arrhythmia.
- Published
- 2011