Diabetes Metab J.  2016 Oct;40(5):406-413. 10.4093/dmj.2016.40.5.406.

Rg3 Improves Mitochondrial Function and the Expression of Key Genes Involved in Mitochondrial Biogenesis in C2C12 Myotubes

• Kim MJ
• Koo YD
• Kim M
• Lim S
• Park YJ
• Chung SS
• Jang HC
• Park KS

• KMID: 2354614
• DOI: http://doi.org/10.4093/dmj.2016.40.5.406

Abstract

BACKGROUND
Panax ginseng has glucose-lowering effects, some of which are associated with the improvement in insulin resistance in skeletal muscle. Because mitochondria play a pivotal role in the insulin resistance of skeletal muscle, we investigated the effects of the ginsenoside Rg3, one of the active components of P. ginseng, on mitochondrial function and biogenesis in C2C12 myotubes.
METHODS
C2C12 myotubes were treated with Rg3 for 24 hours. Insulin signaling pathway proteins were examined by Western blot. Cellular adenosine triphosphate (ATP) levels and the oxygen consumption rate were measured. The protein or mRNA levels of mitochondrial complexes were evaluated by Western blot and quantitative reverse transcription polymerase chain reaction analysis.
RESULTS
Rg3 treatment to C2C12 cells activated the insulin signaling pathway proteins, insulin receptor substrate-1 and Akt. Rg3 increased ATP production and the oxygen consumption rate, suggesting improved mitochondrial function. Rg3 increased the expression of peroxisome proliferator-activated receptor γ coactivator 1α, nuclear respiratory factor 1, and mitochondrial transcription factor, which are transcription factors related to mitochondrial biogenesis. Subsequent increased expression of mitochondrial complex IV and V was also observed.
CONCLUSION
Our results suggest that Rg3 improves mitochondrial function and the expression of key genes involved in mitochondrial biogenesis, leading to an improvement in insulin resistance in skeletal muscle. Rg3 may have the potential to be developed as an anti-hyperglycemic agent.

Keyword

Ginsenoside Rg3; Mitochondria; Panax

MeSH Terms

Adenosine Triphosphate
Blotting, Western
Insulin
Insulin Receptor Substrate Proteins
Insulin Resistance
Mitochondria
Muscle Fibers, Skeletal*
Muscle, Skeletal
Nuclear Respiratory Factor 1
Organelle Biogenesis*
Oxygen Consumption
Panax
Peroxisomes
Polymerase Chain Reaction
Reverse Transcription
RNA, Messenger
Transcription Factors
Adenosine Triphosphate
Insulin
Insulin Receptor Substrate Proteins
Nuclear Respiratory Factor 1
RNA, Messenger
Transcription Factors

Figure

• 

  Fig. 1 Effects of Rg3 on the insulin signaling pathway. In C2C12 myotubes, 100 µM Rg3 was administered for 24 hours with or without (A) 500 µM palmitate or (B) 10 µM antimycin A. Experiment was repeated four times. pIRS-1, phosphorylated insulin receptor substrate-1; IRS-1, insulin receptor substrate-1.

• 

  Fig. 2 Effects of Rg3 on mitochondrial function. In C2C12 myotubes, 100 µM Rg3 was administered for 24 hours with or without 10 µM antimycin A. (A) Cellular adenosine triphosphate (ATP) levels. (B) Representative graphs of oxygen consumption rate (OCR). OCR was measured under the basal conditions, following the addition of oligomycin, carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone (FCCP), and antimycin A/rotenone. (C) Basal OCR. Each experiment was repeated more than four times. Data was presented as mean±standard error of mean. aP<0.05.

• 

  Fig. 3 Effects of Rg3 on the expression of key genes involved in mitochondrial biogenesis. In C2C12 myotubes, 100 µM Rg3 was administered for 24 hours with or without 10 µM antimycin A. (A) Expression of mitochondrial complexes by Western blot. (B) mRNA expression of mitochondrial complexes by quantitative reverse transcription polymerase chain reaction (RT-PCR). (C) mRNA expression of peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), nuclear respiratory factor 1 (NRF-1), and mitochondrial transcription factor (Tfam) by quantitative RT-PCR. RT-PCR was performed in duplicate, and each experiment was repeated five times. aP<0.05.

• 

  Fig. 4 Effects of Rg3 and adenosine monophosphate (AMP)-activated protein kinase (AMPK) pathway. After pretreatment of 10 µM antimycin A, 100 µM Rg3 was administered for 24 hours with or without 10 µM compound C in C2C12 myotubes. The expression of mitochondrial complexes and AMPK was evaluated by Western blot. pAMPK, phosphorylated AMPK.

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