Dutta Asmita, Sinha Deepak Kumar
Department of Biological Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
Department of Biological Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
Open Biol. 2017 Jul;7(7). doi: 10.1098/rsob.170063.
In zebrafish embryos, the maternally supplied pool of ATP is insufficient to power even the earliest of developmental events (0-3 hpf) such as oocyte-to-embryo transition (OET). The embryos generate an additional pulse (2.5 h long) of ATP (1.25-4 hpf) to achieve the embryonic ATP homeostasis. We demonstrate that the additional pulse of ATP is needed for successful execution of OET. The maternally supplied yolk lipids play a crucial role in maintaining the embryonic ATP homeostasis. In this paper, we identify the source and trafficking routes of free fatty acids (FFAs) that feed the mitochondria for synthesis of ATP. Interestingly, neither the maternally supplied pool of yolk-FFA nor the yolk-FACoA (fatty acyl coenzyme A) is used for ATP homeostasis during 0-5 hpf in zebrafish embryos. With the help of lipidomics, we explore the link between lipid droplet (LD)-mediated lipolysis and ATP homeostasis in zebrafish embryos. Until 5 hpf, the embryonic LDs undergo extensive lipolysis that generates FFAs. We demonstrate that these newly synthesized FFAs from LDs are involved in the maintenance of embryonic ATP homeostasis, rather than the FFAs/FACoA present in the yolk. Thus, the LDs are vital embryonic organelles that maintain the ATP homeostasis during early developmental stages (0-5 hpf) in zebrafish embryos. Our study highlights the important roles carried on by the LDs during the early development of the zebrafish embryos.
在斑马鱼胚胎中，母源提供的ATP池甚至不足以支持最早的发育事件（受精后0至3小时），如卵母细胞到胚胎的转变（OET）。胚胎会产生额外的ATP脉冲（持续2.5小时）（受精后1.25至4小时），以实现胚胎ATP稳态。我们证明，成功执行OET需要额外的ATP脉冲。母源提供的卵黄脂质在维持胚胎ATP稳态中起关键作用。在本文中，我们确定了为线粒体提供合成ATP所需游离脂肪酸（FFA）的来源和运输途径。有趣的是，在斑马鱼胚胎受精后0至5小时期间，母源提供的卵黄FFA池和卵黄脂肪酰辅酶A（FACoA）都未用于ATP稳态。借助脂质组学，我们探索了斑马鱼胚胎中脂滴（LD）介导的脂解作用与ATP稳态之间的联系。直到受精后5小时，胚胎LDs经历广泛的脂解作用，产生FFA。我们证明，这些新合成的来自LDs的FFA参与维持胚胎ATP稳态，而不是卵黄中存在的FFA/FACoA。因此，LDs是至关重要的胚胎细胞器，在斑马鱼胚胎早期发育阶段（受精后0至5小时）维持ATP稳态。我们的研究突出了LDs在斑马鱼胚胎早期发育过程中所起的重要作用。
