Beta-Oxidation Is Essential for Mouse Oocyte Developmental Competence and Early Embryo Development
Beta-Oxidation Is Essential for Mouse Oocyte Developmental Competence and Early Embryo Development
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DOI：
10.1095/biolreprod.110.084145
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发表时间：
2010-12-01
影响因子：
3.6
通讯作者：
Robker, Rebecca L.
中科院分区：
文献类型：
--
作者：
Dunning, Kylie R.;Cashman, Kara;Robker, Rebecca L.
卵母细胞和胚胎的新陈代谢与其随后的发育能力密切相关。脂类是细胞能量的有效来源，但对卵母细胞成熟和早期胚胎发育过程中的脂类代谢知之甚少。脂质通过脂肪酸的β-氧化在线粒体内生成ATP，限速步骤由肉碱棕榈酰转移酶I(CPT1B)催化，这一过程也需要肉碱。我们试图研究β-氧化在卵母细胞成熟和植入前发育过程中的调节和作用。实时定量RT-PCR检测Cpt1b在小鼠卵丘-卵母细胞复合体(COCs)中的表达，发现在体内用人绒毛膜促性腺激素(5IU)诱导卵母细胞成熟和排卵以及囊胚期胚胎中Cpt1b的表达增加。在表皮生长因子(3 ng/ml)和卵泡刺激素(50mLU/ml)诱导下，用[H-3]棕榈酸产生(H2O)-H-3衡量的β-氧化作用显著高于未成熟的COCs。分别用依托莫昔尔(CPT1B的抑制剂)或L肉碱抑制或上调β-氧化作用后的胚胎发育率来评价脂质代谢对卵母细胞发育能力和早期胚胎发育的重要性。在卵母细胞成熟或受精卵分裂过程中抑制β-氧化会损害随后的囊胚发育。相反，在卵母细胞成熟期间补充L肉碱显著增加了β-氧化，改善了发育能力，并且在没有碳水化合物能量供应的情况下，显著增加了2-细胞分裂。因此，肉碱是卵母细胞发育的重要辅助因子，而脂肪酸是卵母细胞和胚胎发育的重要能量来源。
Oocyte and embryo metabolism are closely linked with their subsequent developmental capacity. Lipids are a potent source of cellular energy, yet little is known about lipid metabolism during oocyte maturation and early embryo development. Generation of ATP from lipids occurs within mitochondria via beta-oxidation of fatty acids, with the rate-limiting step catalyzed by carnitine palmitoyl transferase I (CPT1B), a process also requiring carnitine. We sought to investigate the regulation and role of beta-oxidation during oocyte maturation and preimplantation development. Expression of Cpt1b mRNA, assessed by real-time RT-PCR in murine cumulus-oocyte complexes (COCs), increased following hormonal induction of oocyte maturation and ovulation in vivo with human chorionic gonadotropin (5 IU) and in embryos reaching the blastocyst stage. Beta-oxidation, measured by the production of (H2O)-H-3 from [H-3]palmitic acid, was significantly increased over that in immature COCs following induction of maturation in vitro with epidermal growth factor (3 ng/ml) and follicle-stimulating hormone (50 mlU/ml). The importance of lipid metabolism for oocyte developmental competence and early embryo development was demonstrated by assessing the rate of embryo development following inhibition or upregulation of beta-oxidation with etomoxir (an inhibitor of CPT1B) or L-carnitine, respectively. Inhibition of beta-oxidation during oocyte maturation or zygote cleavage impaired subsequent blastocyst development. In contrast, L-carnitine supplementation during oocyte maturation significantly increased beta-oxidation, improved developmental competence, and in the absence of a carbohydrate energy supply, significantly increased 2-cell cleavage. Thus, carnitine is an important cofactor for developing oocytes, and fatty acids are an important energy source for oocyte and embryo development.