Hexokinase I expression and activity in embryonic mouse heart during early and late organogenesis
Hexokinase I expression and activity in embryonic mouse heart during early and late organogenesis
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DOI：
10.1007/s004180050417
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发表时间：
1999-11-01
影响因子：
2.3
通讯作者：
Branch, S
中科院分区：
文献类型：
--
作者：
Fritz, HL;Smoak, IW;Branch, S
己糖激酶（HK）催化葡萄糖代谢的第一步，即将葡萄糖转化为葡萄糖 - 6 - 磷酸（G6P）。已鉴定出四种HK同工酶，其中HK - I在胚胎和胎儿组织中占主导地位。HK - I在着床前胚胎和胎儿阶段已被研究，但对其在着床后早期胚胎中的活性或表达知之甚少。我们评估了在器官发生早期[妊娠第9.5天（gd 9.5）]和晚期（gd 13.5）胚胎小鼠心脏中的HK - I表达、HK - I活性以及糖酵解代谢。免疫组织化学显示，HK - I在这两个阶段主要定位于心脏，在gd 13.5时表达更强。SDS - PAGE/蛋白质印迹分析后的光密度测定证实，gd 13.5心脏中可免疫检测到的HK - I蛋白水平高于gd 9.5。相比之下，逆转录 - 聚合酶链反应显示gd 9.5的HK - I mRNA表达高于gd 13.5。同样，心脏HK - I活性（葡萄糖转化为G6P）和糖酵解（葡萄糖转化为乳酸）在gd 9.5时高于gd 13.5。这些结果表明，在器官发生过程中胚胎心脏中HK - I的表达和活性受到复杂的调控，涉及酶的内在活性随发育而变化。在心脏发生的这个关键阶段，HK - I似乎在葡萄糖代谢中起重要作用。
Hexokinase (HK) catalyzes the first step in glucose metabolism, that is, the conversion of glucose to glucose-6-phosphate (G6P). Four HK isoforms have been identified, of which HK-I is predominant in embryonic and fetal tissues. HK-I has been studied in preimplantation embryos and in fetal stages, but little is known about its activity or expression in the early postimplantation embryo. We evaluated HK-I expression, HK-I activity, and glycolytic metabolism in the embryonic mouse heart during early [gestational day (gd) 9.5] and late (gd 13.5) organogenesis. Immunohistochemistry demonstrated that HK-I is localized mainly in the heart at both stages, with stronger expression on gd 13.5. Densitometry after SDS-PAGE/western analysis confirmed higher immunodetectable HK-I protein levels in hearts on gd 13.5 vs gd 9.5. By contrast, RT-PCR demonstrated higher HK-I mRNA expression on gd 9.5 vs gd 13.5. Similarly, cardiac HK-I activity (conversion of glucose to G6P) and glycolysis (conversion of glucose to lactate) were higher on gd 9.5 than on gd 13.5. These results suggest a complex regulation of HK-I expression and activity in the embryonic heart during organogenesis, involving a change in the intrinsic activity of the enzyme with development. HK-I appears to play an important role in glucose metabolism during this critical stage of cardiogenesis.