WCU Biomodulation Major, Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Korea.
Biol Reprod. 2012 Sep 13;87(3):57. doi: 10.1095/biolreprod.112.101345. Print 2012 Sep.
Glucose is an important monosaccharide required to generate energy in all cells. After entry into cells, glucose is phosphorylated to glucose-6-phosphate and then transformed into glycogen or metabolized to produce energy. Glucose phosphate isomerase (GPI) catalyzes the reversible isomerization of glucose-6-phosphate and fructose-6-phosphate. Without GPI activity or fructose-6-phosphate, many steps of glucose metabolism would not occur. The requirement for GPI activity for normal functioning of primordial germ cells (PGCs) needs to be identified. In this study, we first examined the expression of chicken GPI during early embryonic development and germ cell development. GPI expression was strongly and ubiquitously detected in chicken early embryos and embryonic tissues at Embryonic Day 6.5 (E6.5). Continuous GPI expression was detected in PGCs and germ cells of both sexes during gonadal development. Specifically, GPI expression was stronger in male germ cells than in female germ cells during embryonic development and the majority of post-hatching development. Then, we used siRNA-1499 to knock down GPI expression in PGCs. siRNA-1499 caused an 85% knockdown in GPI, and PGC proliferation was also affected 48 h after transfection. We further examined the knockdown effects on 28 genes related to the glycolysis/gluconeogenesis pathway and the endogenous glucose level in chicken PGCs. Among genes related to glycolysis/gluconeogenesis, 20 genes showed approximately 3-fold lower expression, 4 showed approximately 10-fold lower, and 2 showed approximately 100-fold lower expression in knockdown PGCs. The endogenous glucose level was significantly reduced in knockdown PGCs. We conclude that the GPI gene is crucial for maintaining glycolysis and supplying energy to developing PGCs.
葡萄糖是所有细胞产生能量所必需的重要单糖。进入细胞后，葡萄糖被磷酸化生成葡萄糖-6-磷酸，然后转化为糖原或代谢产生能量。葡萄糖磷酸异构酶（GPI）催化葡萄糖-6-磷酸和果糖-6-磷酸的可逆异构化。没有 GPI 活性或果糖-6-磷酸，葡萄糖代谢的许多步骤都不会发生。需要确定 GPI 活性对于原始生殖细胞（PGC）正常功能的要求。在这项研究中，我们首先检查了鸡 GPI 在早期胚胎发育和生殖细胞发育过程中的表达。GPI 表达在鸡早期胚胎和胚胎组织中强烈且广泛存在，在胚胎发育第 6.5 天（E6.5）时达到高峰。在生殖腺发育过程中，PGC 和雌雄生殖细胞中都持续表达 GPI。具体而言，在胚胎发育和孵化后的大部分发育过程中，雄性生殖细胞中的 GPI 表达强于雌性生殖细胞。然后，我们使用 siRNA-1499 敲低 PGC 中的 GPI 表达。siRNA-1499 使 GPI 表达降低了 85%，并且转染后 48 小时 PGC 增殖也受到影响。我们进一步检查了 siRNA-1499 对鸡 PGC 中与糖酵解/糖异生途径相关的 28 个基因和内源性葡萄糖水平的敲低作用。在与糖酵解/糖异生相关的基因中，20 个基因的表达水平降低了约 3 倍，4 个基因降低了约 10 倍，2 个基因降低了约 100 倍。敲低 PGC 中的内源性葡萄糖水平显著降低。我们得出结论，GPI 基因对于维持糖酵解和为发育中的 PGC 提供能量至关重要。
