AR基因剔除引發老鼠肌肉粒線體功能異常

Androgen Receptor Gene Knockout Induced Mitochondrial Dysfunction in Mice Muscle

林浩瑋(Hao-Wei Lin)

指導教授 ： 高淑慧

臺北醫學大學/醫學科技學院/醫學檢驗暨生物技術學系/碩士(2012年)

https://doi.org/10.6831/TMU.2012.00003

摘要

雄性素受體 (androgen receptor, AR) 與肌肉生成 (myogenesis) 息息相關，雄性素 (androgen) 被證實能促進肌肉的分化，影響肌肉大小與粒線體(mitochondria)功能；而粒線體是細胞內提供能量合成與代謝的重要胞器，粒線體功能缺損時也被發現會降低肌肉的分化能力，AR出現變異會引發粒線體膜電位下降及細胞凋亡。所以本研究推測AR基因缺損可能影響粒線體功能，進而降低肌肉細胞分化的能力及造成肌肉萎縮等症狀。本研究以AR基因剔除鼠(ARKO mice)為實驗模式進行實驗分析，以同週齡的wild type老鼠 (WT mice) 作為對照組進行粒線體功能的分析。首先從組織化學染色可觀察到ARKO mice在粒線體呼吸酵素複合體Complex I (NADH dehydrogenase)、Complex II (succinate dehydrogenase) 、Complex IV (cytochrome c oxidase) 的活性降為WT的0.52倍； ARKO mice肌肉組織中ATP含量與肌纖維束基礎耗氧量也降為WT的0.53倍。進一步以電子顯微鏡檢測粒線體構形較為鬆散。定量粒線體DNA的拷貝數 (mitochondrial DNA copy number) 及粒線體genome轉錄的mRNA (mtCO2, mtND1) 及其轉譯的蛋白都降為WT的0.46及0.63倍，且組織內由細胞核genome轉錄的粒線體呼吸酵素複合體mRNA (CO4) 及其轉譯的蛋白表現量代償性增加為WT的1.88倍。進一步分析其生合成(biogenesis)調控因子的變化發現，peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC1α) 有高達8.51倍的增加，但是下游的調控因子nuclear respiratory factor 1 (NRF1) 及mitochondrial transcription factor A僅有小幅度1.43倍的提升，推測AR基因的缺損可能影響PGC1-α對NRF1的調控能力。綜合研究結果我們推測：AR基因缺損確實降低粒線體氧化磷酸化的效能，並影響肌肉細胞分化的能力。

關鍵字

雄性素受體 ； 肌肉生成 ； 氧化磷酸化 ； 粒線體生合成

並列摘要

Myogenesis is under the influence of androgen receptors (AR). Androgen is demonstrated to regulate the differentiation of mesenchymal stem cells, promote the enlargement of skeletal muscle cells and regulate the efficacy of oxidative phosphorylation. Mitochondria are regarded as one of the most important organ that they are involved in a range of processes, such as ATP generation, signaling, cellular differentiation, cell death as well as the control of the cell cycle and cell growth. We speculate that deletions of AR gene will induced mitochondrial dysfunction and suppress the differentiations of myogenic precursor cells. The androgen receptor knockout mice (ARKO) were used in this study. The skeletal muscles of ARKO mice were harvested to recognize the effects of AR gene knockout on mitochondria dysfunction and muscle weakness. The mitochondrial ultrastructure were disorganized. The capacity of mitochondrial oxidative phosphorylation, ATP contents, respiration control, mitochondrial DNA copy numbers and mtDNA encoded mRNA expressions (i.e. mtND1, mtCO2, mtATP6) were decreased. But the expressions of nuclear encoded mitochondrial mRNA (CO4) and proteins were increased. A significant increase of the peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC1-α), the major regulators of mitochondrial biogenesis, was found in the ARKO mice. But the compensatory up-regulation of nuclear respiratory factor 1 (NRF1) gene were attenuated. These findings indicate that AR plays a crucial role in mitochondrial oxidative phosphorylation and myogenesis.

並列關鍵字

androgen receptor ； myogenesis ； oxidative phosphorylation ； mitochondrial biogenesis

參考文獻

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