Journal of Life Science (생명과학회지)

Korean Society of Life Science (한국생명과학회)
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Regulation of Skeletal Muscle Differentiation by Akt

Akt에 의한 근육세포의 분화 조절

  • Woo, Dae-Han (MRC for Ischemic Tissue Regeneration, Medical Research Institute, Department of Pharmacology, Pusan National University School of Medicine) ;
  • Yun, Sung-Ji (MRC for Ischemic Tissue Regeneration, Medical Research Institute, Department of Pharmacology, Pusan National University School of Medicine) ;
  • Kim, Eun-Kyoung (MRC for Ischemic Tissue Regeneration, Medical Research Institute, Department of Pharmacology, Pusan National University School of Medicine) ;
  • Ha, Jung-Min (MRC for Ischemic Tissue Regeneration, Medical Research Institute, Department of Pharmacology, Pusan National University School of Medicine) ;
  • Shin, Hwa-Kyoung (Department of Anatomy, Pusan National University School of Korean Medicine) ;
  • Bae, Sun-Sik (MRC for Ischemic Tissue Regeneration, Medical Research Institute, Department of Pharmacology, Pusan National University School of Medicine)
  • 우대한 (부산대학교 의학전문대학원 약리학교실) ;
  • 윤성지 (부산대학교 의학전문대학원 약리학교실) ;
  • 김은경 (부산대학교 의학전문대학원 약리학교실) ;
  • 하정민 (부산대학교 의학전문대학원 약리학교실) ;
  • 신화경 (부산대학교 한의학전문대학원 해부학교실) ;
  • 배순식 (부산대학교 의학전문대학원 약리학교실)
  • Received : 2012.01.06
  • Accepted : 2012.03.07
  • Published : 2012.04.30
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Abstract

Akt plays an important role in a variety of cellular physiologies such as growth, proliferation, and differentiation. In skeletal muscle, Akt has been implicated in regulating regeneration, hypertrophy, and atrophy. In this study, the role of Akt has been examined during skeletal muscle differentiation. Culturing C2C12 myoblasts under low serum (1% horse serum) and high density converted cell morphology from a round shape to an elongated and multi-nucleated shape. Morphological changes were initiated from day 2 of differentiation. In addition, the expression of both myogenin G and myogenin D was elevated from day 2 of differentiation. Skeletal muscle differentiation was abolished by silencing Akt1 or Akt2, but was significantly enhanced by the over-expression of either Akt1 or Akt2. The activation of Akt was observed from day 2 of differentiation and disappeared after day 7. The expression of kruppel-like factor 4 was observed from day 6 of differentiation. Moreover, this expression was blocked in cells silencing either Akt1 or Akt2. In addition, the promoter activity of kruppel-like factor 4 was significantly reduced in cells silencing Akt1 or Akt2. These results suggest that Akt regulates skeletal muscle differentiation through the regulation of kruppel-like factor 4 expression.

Akt는 다양한 세포에서 성장, 발달, 증식, 분화와 같은 생리적 활성에 중요한 역할을 하고 골격근 세포에서 Akt는 재생 및 비대와 위축을 조절한다고 알려져 있다. 골격근 세포의 분화에 있어서 Akt의 역할을 밝히고자 본 연구를 수행하였다. 골격근 세포를 분화 시키기 위해 고밀도 및 저농도의 serum 상태에서 배양하며, 분화된 C2C12 근아세포는 둥근 모양에서 다핵을 가진 긴 모양으로 바뀐다. 이러한 형태학적 변화는 분화 시킨 후 2일부터 일어났다. 또한, 골격근 분화 표지인자인 myogenin D와 myogenin G의 발현은 2일 후 관찰되었다. C2C12 세포주에 Akt1 또는 Akt2의 발현을 저하시키면 이와 더불어 골격근으로의 분화도 저해됨을 확인하였고, 이와는 반대로 Akt1 또는 Akt2를 과발현 시키면 골격근으로 분화가 촉진됨을 알 수 있었다. 이와 더불어 Akt의 활성은 분화유도 2일 후부터 관찰되었고 7일 이후로는 감소하였다. Kruppel-like factor 4의 발현은 6일부터 증가하는 것이 관찰이 되었다. Kruppel-like factor 4의 발현 또한 Akt1 또는 Akt2의 발현양이 감소된 C2C12 근아세포에서 줄어들어 있는 것을 확인하였다. 또한 Kruppel-like factor 4의 프로모터 부위에 대한 전사조절능력이 Akt1 또는 Akt2의 발현을 저하시켰을 때 같이 떨어짐을 확인하였다. 이러한 결과들로 보아 Akt가 골격근 분화를 조절하는데 있어 중요하며, Kruppel-like factor 4 발현이 이를 조절하는 데 있어 중요한 역할을 할 것이라 판단된다.

Keywords

References

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