RRC ID 69909
Author Iseki Y, Ono Y, Hibi C, Tanaka S, Takeshita S, Maejima Y, Kurokawa J, Murakawa M, Shimomura K, Sakamoto K.
Title Opening of Intermediate Conductance Ca2+-Activated K+ Channels in C2C12 Skeletal Muscle Cells Increases the Myotube Diameter via the Akt/Mammalian Target of Rapamycin Pathway.
Journal J Pharmacol Exp Ther
Abstract The activation of potassium channels and the ensuing hyperpolarization in skeletal myoblasts are essential for myogenic differentiation. However, the effects of K+ channel opening in myoblasts on skeletal muscle mass are unclear. Our previous study revealed that pharmacological activation of intermediate conductance Ca2+-activated K+ channels (IKCa channels) increases myotube formation. In this study, we investigated the effects of 5,6-dichloro-1-ethyl-1,3-dihydro-2H-benzimidazol-2-one (DCEBIO), a Ca2+-activated K+ channel opener, on the mass of skeletal muscle. Application of DCEBIO to C2C12 cells during myogenesis increased the diameter of C2C12 myotubes in a concentration-dependent manner. This DCEBIO-induced hypertrophy was abolished by gene silencing of IKCa channels. However, it was resistant to 1 µM but sensitive to 10 µM TRAM-34, a specific IKCa channel blocker. Furthermore, DCEBIO reduced the mitochondrial membrane potential by opening IKCa channels. Therefore, DCEBIO should increase myotube mass by opening of IKCa channels distributed in mitochondria. Pharmacological studies revealed that mitochondrial reactive oxygen species (mitoROS), Akt, and mammalian target of rapamycin (mTOR) are involved in DCEBIO-induced myotube hypertrophy. An additional study demonstrated that DCEBIO-induced muscle hypertrophic effects are only observed when applied in the early stage of myogenic differentiation. In an in vitro myotube inflammatory atrophy experiment, DCEBIO attenuated the reduction of myotube diameter induced by endotoxin. Thus, we concluded that DCEBIO increases muscle mass by activating the IKCa channel/mitoROS/Akt/mTOR pathway. Our study suggests the potential of DCEBIO in the treatment of muscle wasting diseases. SIGNIFICANCE STATEMENT: Our study shows that 5,6-dichloro-1-ethyl-1,3-dihydro-2H-benzimidazol-2-one (DCEBIO), a small molecule opener of Ca2+-activated K+ channel, increased muscle diameter via the mitochondrial reactive oxygen species/Akt/mammalian target of rapamycin pathway. And DCEBIO overwhelms C2C12 myotube atrophy induced by endotoxin challenge. Our report should inform novel role of K+ channel in muscle development and novel usage of K+ channel opener such as for the treatment of muscle wasting diseases.
Volume 376(3)
Pages 454-462
Published 2021-3-1
DOI 10.1124/jpet.120.000290
PII jpet.120.000290
PMID 33376149
MeSH Animals Benzimidazoles / pharmacology* Cell Differentiation / drug effects Cell Line Ion Channel Gating / drug effects* Mice Mitochondria / drug effects Mitochondria / metabolism Muscle Fibers, Skeletal / cytology Muscle Fibers, Skeletal / drug effects* Muscle Fibers, Skeletal / metabolism Muscle, Skeletal / cytology* Potassium Channels, Calcium-Activated / chemistry Potassium Channels, Calcium-Activated / metabolism* Proto-Oncogene Proteins c-akt / metabolism* Signal Transduction / drug effects TOR Serine-Threonine Kinases / metabolism*
IF 3.561
Human and Animal Cells C2C12(RCB0987)