High-throughput assay for modulators of mitochondrial membrane potential identifies a novel compound with beneficial effects on db/db mice.
OBJECTIVE
Recently, several drugs have been shown to exert beneficial effects for metabolic syndrome through mild regulation of mitochondrial function. Hence, we explored a strategy of targeting mitochondrial function to improve glucose and lipid metabolism.


METHODS
Mitochondrial membrane potential (Deltapsim) is a marker of mitochondrial function; therefore, we set up a high-throughput screening assay of Deltapsim in L6 myotubes. The effects of a selected lead compound were investigated in vitro and in vivo in relation to metabolic syndrome.


RESULTS
A novel small-molecule compound, C1, was identified through this high-throughput screening. C1 depolarized Deltapsim in L6 myotubes without cytotoxicity and led to increased cellular AMP-to-ATP ratio, activation of AMP-activated protein kinase (AMPK), and enhanced glucose uptake. It also stimulated the AMPK pathway in HepG2 cells, leading to decreased lipid content. Intriguingly, C1 inhibited respiration in L6 myotubes but did not affect respiration in isolated muscle mitochondria, suggesting that it may depolarize Deltapsim indirectly by affecting the supply of electron donors. Acute administration of C1 in C57BL/6J mice markedly increased fat oxidation and the phosphorylation of AMPK and acetyl-CoA carboxylase in the liver. In diabetic db/db mice, chronic administration of C1 significantly reduced hyperglycemia, plasma fatty acids, glucose intolerance, and the mRNA levels of phosphoenolpyruvate carboxykinase and glucose-6-phosphatase in the liver.


CONCLUSIONS
Our results demonstrate a novel small molecule that mildly depolarizes Deltapsim and is able to improve glucose and lipid metabolism to exert beneficial effects for metabolic syndrome. These findings suggest that compounds regulating mitochondrial function may have therapeutic potential for type 2 diabetes.
Qiu
Bei-Ying
BY
National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
Turner
Nigel
N
Li
Yuan-Yuan
YY
Gu
Min
M
Huang
Meng-Wei
MW
Wu
Fang
F
Pang
Tao
T
Nan
Fa-Jun
FJ
Ye
Ji-Ming
JM
Li
Jing-Ya
JY
Li
Jia
J
D000263:Adenylate Kinase / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002784:Cholesterol / Q000378:metabolism; D003847:Deoxyglucose / Q000378:metabolism; D056945:Hep G2 Cells / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007773:Lactates / Q000378:metabolism; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology*; D008687:Metformin / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D051336:Mitochondrial Membranes / Q000187:drug effects / Q000502:physiology*; D032446:Myoblasts / Q000187:drug effects / Q000502:physiology; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D014280:Triglycerides / Q000378:metabolism
D007773:Lactates; D014280:Triglycerides; D008687:Metformin; D002784:Cholesterol; D003847:Deoxyglucose; D000263:Adenylate Kinase