Meiotic induction in cumulus cell-enclosed mouse oocytes: Involvement of the pentose phosphate pathway
Meiotic induction in cumulus cell-enclosed mouse oocytes: Involvement of the pentose phosphate pathway
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DOI：
10.1095/biolreprod58.4.1084
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发表时间：
1998-04-01
影响因子：
3.6
通讯作者：
Leese, HJ
中科院分区：
文献类型：
--
作者：
Downs, SM;Humpherson, PG;Leese, HJ
在这项研究中，我们测试的假设，戊糖磷酸途径（PPP）参与小鼠卵母细胞减数分裂诱导。电子受体亚甲蓝、吩嗪乙硫酸盐（PES）和吡咯啉-5-羧酸盐（P5 C）将NADPH氧化为NADP，并激活PPP的NADP依赖性酶。这些化合物中的每一个引发了次黄嘌呤逮捕卵丘细胞封闭的卵母细胞在17至18小时的培养物中的减数分裂成熟的剂量依赖性增加。超过96%的卵母细胞在最高浓度的P5 C和PES测试（分别为250和1 μ M）进行生殖囊泡破裂（GVB）相比，只有45-52%的控制卵母细胞。P5 C对裸卵也有刺激作用。微滴培养物中的能量底物分析显示，PES处理的卵母细胞-卵丘细胞复合物的葡萄糖消耗增加了3.6倍，这与GVB的刺激有关。另一方面，干扰葡萄糖利用的2-脱氧葡萄糖阻止了P5 C引起的成熟诱导。夹竹桃素和diphenyleneiodonium，NADPH氧化酶的抑制剂，阻止减数分裂成熟的FSH的存在或不存在。促性腺激素诱导的成熟也被6-氨基烟酰胺（6-AN）和脱氢表雄酮（DHEA）（PPP的两种NADP依赖性酶的抑制剂）阻止，这伴随着葡萄糖消耗的抑制。磷酸核糖焦磷酸（PRPP）是嘌呤代谢所需的重要化合物，可由PPP氧化臂的终产物核糖-5-磷酸形成。核糖，它可以代谢为PRPP，增加PRPP合成的复合物和诱导减数分裂成熟时，添加到次黄嘌呤逮捕的卵丘细胞封闭的卵母细胞在无葡萄糖培养基中的FSH的存在和不存在。复合物内的PRPP水平也增加了葡萄糖和FSH，但次黄嘌呤，6-AN和DHEA降低。此外，外源性PRPP刺激成熟次黄嘌呤逮捕卵母细胞。这些结果支持的命题，葡萄糖代谢通过PPP是重要的减数分裂诱导机制，并可能涉及产生PRPP的行为，至少部分，通过嘌呤代谢途径。
In this study we tested the hypothesis that the pentose phosphate pathway (PPP) participates in the meiotic induction of mouse oocytes. The electron accepters methylene blue, phenazine ethosulfate (PES), and pyrroline-5-carboxylate (P5C) oxidize NADPH to NADP and activate the NADP-dependent enzymes of the PPP. Each of these compounds triggered a dose-dependent increase in meiotic maturation in hypoxanthine-arrested cumulus cell-enclosed oocytes during 17- to 18-h cultures. More than 96% of the oocytes underwent germinal vesicle breakdown (GVB) at the highest concentrations of P5C and PES tested (250 and 1 mu M, respectively) as compared to only 45-52% of control oocytes. P5C was also stimulatory to denuded oocytes. Analysis of energy substrates in microdrop cultures revealed a 3.6-fold increase in glucose consumption by PES-treated oocyte-cumulus cell complexes that was associated with stimulation of GVB. On the other hand, 2-deoxyglucose, which interferes with glucose utilization, prevented the induction of maturation brought about by P5C. Apocynin and diphenyleneiodonium, inhibitors of NADPH oxidase, prevented meiotic maturation in the presence or absence of FSH. Gonadotropin-induced maturation was also prevented by 6-aminonicotinamide (6-AN) and dehydroepiandrosterone (DHEA), inhibitors of the two NADP-dependent enzymes of the PPP, and this was accompanied by suppression of glucose consumption. Phosphoribosylpyrophosphate (PRPP) is an important compound required in purine metabolism and can be formed from the end product of the oxidative arm of the PPP, ribose-5-phosphate. Ribose, which can be metabolized to PRPP, increased PRPP synthesis in complexes and induced meiotic maturation when added to hypoxanthine-arrested cumulus cell-enclosed oocytes in glucose-free medium in both the presence and absence of FSH. PRPP levels within complexes were also increased by glucose and FSH, but were reduced by hypoxanthine, 6-AN, and DHEA. In addition, exogenous PRPP stimulated maturation in hypoxanthine-arrested oocytes. These results support the proposition that glucose metabolism through the PPP is important in the meiotic induction mechanism and may involve the generation of PRPP that acts, at least in part, through the purine metabolizing pathways.