Diabetes and Metabolism Journal

Korean Diabetes Association (대한당뇨병학회)
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Effects of PPAR-$\alpha$ and -$\gamma$ Agonists on Fatty Acid Metabolism of Muscle Cells in Hyperlipidemic and Hyperglycemic Conditions

고지방 및 고포도당 조건에서 배양한 근육 세포의 지방산 대사에 미치는 PPAR-$\alpha$와 PPAR-$\gamma$ agonist의 효과

Lee, Yong-Jik;Zhao, Zheng-Shan;Kim, Soo-Kyung;Kim, Hae-Jin;Shim, Wan-Sub;Ahn, Chul-Woo;Lee, Hyun-Chul;Cha, Bong-Soo
이용직;조정산;김수경;김혜진;심완섭;안철우;이현철;차봉수

  • Published : 2006.09.30
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Abstract

Background: Studies for the regulation of fatty acid metabolism are deficient relatively in skeletal muscle and heart. The investigations in pathological conditions for malonyl-CoA decarboxylase (MCD) and for the relation of MCD and PPAR-$\alpha$․-γ agonists are insufficient in particular. Methods: In the current study, fully differentiated H9c2 muscle cells were exposed to pathological conditions such as hyperlipidemic (0.1 mM Palmitate) and hyperglycemic (16.5 mM Glucose) condition with 5 uM PPAR-γ agonist (rosiglitazone) and 10 uM PPAR-$\alpha$ agonist (WY14,643) and then experiments such as MCD activity assay, MCD real-time RT-PCR, MCD reporter gene assay, MCD Western blotting, PPAR-$\alpha$ Western blotting, and palmitate oxidation test were carried out. Results: Only PPAR-$\alpha$ agonist increased MCD activity. In the result of real-time RT-PCR, both PPAR-$\alpha$ and PPAR-γ agonists elevated MCD mRNA expression in hyperlipidemic condition. MCD protein expression was decreased in hyperlipidemic condition, however, increased in rosiglitazone, or WY14,643 treated conditions. Rosiglitazone, and WY14,643 treated groups showed incresed MCD protein expression in hyperglycemic condition. Hyperlipidemic control group and PPAR-$\alpha$․ﾇ-γ agonists treated groups presented about 3.8 times more increased palmitate oxidation level than normolipidemic control group in hyperlipidemic condition. PPAR-$\alpha$ agonist treated group showed 49% more increased palmitate oxidation rate than hyperlipidemic control group in primary cultured rat skeletal muscle cells. The amount of palmitate oxidation from differentiated H9c2 muscle cells that had overexpressed PPAR-$\alpha$ structural genes was more increased than control group. Conclusion: This study suggests that PPAR-$\alpha$ agonist ameliorates the defects induced by hyperlipidemic condition through the regulation of MCD. In summary, a closely reciprocal relation among PPAR-$\alpha$ agonist, MCD, and fatty acid oxidation existed distinctly in hyperlipidemic condition, but not in hyperglycemic condition.

연구배경: 골격근과 심장에서 지방산 대사의 조절에 관한 연구는 상대적으로 부족한 실정이다. 특히 지방산 대사에서 필수적인 역할을 할 것으로 추측되는 malonyl-CoA decarboxylase (MCD)와 PPAR-$\alpha$PPAR-$\gamma$ agonist들과의 상호관 계 등에 관한 병리적 조건에서 수행된 연구는 미흡한 상태 이다. 방법: 본 연구에서는 충분히 분화된 H9c2 근육 세포들을 고지방 (0.1 mM palmitate) 및 고포도당 (16.5 mM glucose)같은 병리적 조건에서 5 uM PPAR-$\gamma$ agonist (rosiglitazone) 혹은 10 uM PPAR-$\alpha$ agonist (WY14,643) 를 처리한 상태에서 MCD activity assay, MCD real-time RT-PCR, MCD reporter gene assay, MCD Western blotting, PPAR-$\alpha$ Western blotting, 그리고 지방산 산화 시험 (palmitate oxidation test)등의 실험을 수행하였다. 결과: 병리적 조건에서 감소된 MCD 활성은 PPAR-$\alpha$ agonist인 WY14,643만이 증가시켰다. real-time RT-PCR을 한 결과 PPAR-$\alpha$ 및 PPAR-$\gamma$ agonist들 둘 다 고지방 조건 에서 MCD mRNA 발현을 증가시켰다. MCD 단백질 발현은 고지방 조건에서 감소하였지만 rosiglitazone과 WY14,643을 처리하였을 때 증가하였다. 고포도당 조건에서 고포도당 대조군은 정상 대조군과 단백질 발현에 차이는 없었으나 rosiglitazone과 WY14,643을 처리 하였을 때 MCD 단백질 발현이 증가하였다. 고지방 조건에서 고지방 대조군과 PPAR-$\alpha$․PPAR-$\gamma$ agonist들을 처리한 군들은 정상 대조군보다 3.8배 더 증가한 지방산 산화량을 나타내었다. 배양한 쥐 골격근 세포들에서 지방산 산화 시험 결과는 PPAR-$\alpha$ agonist 처리 군이 고지방 대조군보다 49% 더 증가한 지방산 산화량을 보여 주었다. PPAR-$\alpha$ 구조 유전자가 과 발현된 H9c2 근육 세포들은 대조군보다 지방산 산화량이 더 증가 하였다. 결론: 이상의 연구를 통해서 PPAR-$\alpha$ agonist인 WY14,643은 MCD를 조절함으로써 고지방 조건으로 인해 유도된 대사적 결함들을 완화하는 효과가 있다고 추론할 수 있다. 그러나 PPAR-$\gamma$ agonist인 rosiglitazone은 병리적 조건에서 MCD 및 지방산 산화와 밀접한 상호관계를 보여주지 못했다. 결론적으로 고지방 조건에서 PPAR-$\alpha$ agonist인 WY14,643, MCD, 그리고 지방산 산화 사이에는 밀접한 상호관계가 존재한다. 그러나 고포당 조건에서는 이와 같은 상호관계는 관찰되지 않았다.

Keywords

References

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