Nucleotide variations in mitochondrial DNA and supra-physiological ROS levels in cytogenetically normal cases of premature ovarian insufficiency
Nucleotide variations in mitochondrial DNA and supra-physiological ROS levels in cytogenetically normal cases of premature ovarian insufficiency
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DOI：
10.1007/s00404-010-1623-x
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发表时间：
2010-12-01
影响因子：
2.6
通讯作者：
Dada, Rima
中科院分区：
文献类型：
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作者：
Kumar, Manoj;Pathak, Dhananjay;Dada, Rima
卵巢功能不全（POI）是指40岁以下的卵巢功能停止，其特征是闭经、雌激素水平低下和血清促性腺激素浓度（FSH）升高。它是一种具有多病因发病机制的异质性疾病;然而，大多数病例是特发性的。在特发性POI中，未知机制的参与可能会增加卵母细胞凋亡率。研究表明，活性氧（ROS）水平升高会影响配子的质量。据报道，线粒体电子传递链不同复合物中的突变会破坏电子流，导致形成更多的超氧离子或增加ROS水平。本研究旨在筛选特发性POI（n = 25）和隐匿性卵巢功能不全（OI）（n = 5）患者的线粒体基因组变异。本研究入组了30例诊断为POI和隐匿性OI的患者。从患者和对照组中采集血液样本。酚氯仿法提取DNA。在患者中观察到总共102个核苷酸变异，而对照组中观察到58个核苷酸变异。发现24%的变异是非同义的，76%是同义的。结果发现，48%的变化在复合物I中，8%在复合物III中，24%在复合物IV中，20%在复合物V中的电子传递链。我们发现大多数非同义线粒体变异在呼吸链的复合体I（48%）中，这是最大的酶复合体，并且与氧化应激相关。与对照组相比，病例组的一些非同义致病性改变（p.M31T，p.W239C，p.L128Q）和非致病性改变（ATPase 6：p.T53I，ATPase 6：p.L190F，ATPase 6：p.L199L）显著升高。初步数据表明，线粒体突变和随后的ATP水平下降可能加速卵泡闭锁并导致POI。这项初步研究的结果强调了通过分析不同种族人群中的大量样本来扩展这项研究的必要性，并分析卵母细胞中的ROS水平和线粒体突变，因为它们具有不同的胚胎起源，并在不同的微环境中发育。
Premature ovarian insufficiency (POI) is defined as the cessation of ovarian function under the age of 40 years and is characterized by amenorrhea, hypoestrogenism, and elevated serum gonadotrophin concentration (FSH). It is a heterogeneous disorder with a multicausal pathogenesis; however, majority of cases are idiopathic. In idiopathic POI, involvement of unknown mechanisms may increase rate of oocyte apoptosis. Studies have shown that elevated reactive oxygen species (ROS) levels affect the quality of gametes. Mitochondrial mutations in different complexes of electron transport chain have been reported to disrupt the electron flow which lead to formation of more superoxide ions or increased levels of ROS. This study was aimed to screen the mitochondrial genome for variations in idiopathic POI (n = 25) and occult ovarian insufficiency (OI) (n = 5) patients. 30 patients diagnosed with POI and occult OI were enrolled in this study. Blood samples were collected from the patients and controls. DNA was extracted using phenol chloroform method. A total of 102 nucleotide variations were observed in patients as compared with 58 nucleotide variations in controls. 24% variations were found to be non-synonymous and 76% were synonymous. It was found that 48% variations were in complex I, 8% in complex III, 24% in complex IV, and 20% in complex V of electron transport chain. We found most of the non-synonymous mitochondrial variations in complex I (48%) of the respiratory chain which is the largest enzyme complex and is associated with oxidative stress. Some non-synonymous pathogenic alterations (p.M31T, p.W239C, p.L128Q) and non pathogenic alterations (ATPase6:p.T53I, ATPase6:p.L190F, ATPase6:p.L199L) were found to be significantly higher in cases as compared with controls. The preliminary data suggest that the mitochondrial mutations and subsequent decline in ATP levels may accelerate follicular atresia and lead to POI. The results of this preliminary study highlight the need to extend this study by analyzing large number of samples in different ethnic populations and analyze for ROS levels and mitochondrial mutations in oocytes as they are of different embryonic origin and develop in a different microenvironment.