Crustaceans have an open vascular system in which hemocytes freely circulate in hemolymph. Hemocytes are rich in hemocyanin, a specific oxygen-transport protein in crustaceans; therefore, understanding the response of hemocytes to hypoxia is crucial. Although hemocytes take up glucose during hypoxia, the molecular mechanism of glucose uptake in crustaceans remains unclear. Herein, we identified two highly conserved glucose transporters (GLUT1 and GLUT2) in Macrobrachium nipponense (oriental river prawn) and analyzed their tissue-specific expression patterns. Our immunofluorescence assays showed that GLUT1 and GLUT2 are located on the cell membrane, with a strong GLUT1 signal in primary hemocytes under hypoxia. We found that during acute hypoxia, hypoxia-inducible factor-1α–related metabolic alterations result in decreased mitochondrial cytochrome c oxidase activity, implying a classic glycolytic mechanism. As a proof of concept, we replicated these findings in insect S2 cells. Acute hypoxia significantly induced hypoxia-inducible factor-1α, GLUT1, and pyruvate dehydrogenase kinase isozyme 1 expression in primary hemocytes, and hypoxia-induced increases in glucose uptake and lactate secretion were observed. GLUT1 knockdown induced intracellular reactive oxygen species generation and apoptosis in vitro and in vivo, resulting in increased prawn mortality and more apoptotic cells in their brains, implying a vital function of GLUT1 in hypoxia adaptation. Taken together, our results suggest a close relationship between hypoxia-mediated glycolysis and GLUT1 in hemocytes. These results demonstrated that in crustaceans, adaptation to hypoxia involves glucose metabolic plasticity.

甲壳类动物有一个开放的血管系统，其中血细胞在血淋巴中自由循环。血细胞富含血蓝蛋白，这是甲壳类动物体内一种特殊的氧运输蛋白；因此，了解血细胞对缺氧的反应至关重要。尽管血细胞在缺氧期间会吸收葡萄糖，但甲壳类动物吸收葡萄糖的分子机制仍不清楚。在此，我们在日本沼虾中鉴定了两种高度保守的葡萄糖转运蛋白（GLUT1 和 GLUT2）（东方河虾）并分析了它们的组织特异性表达模式。我们的免疫荧光测定显示 GLUT1 和 GLUT2 位于细胞膜上，在缺氧的原代血细胞中具有强 GLUT1 信号。我们发现在急性缺氧期间，缺氧诱导因子 1α 相关的代谢改变导致线粒体细胞色素c氧化酶活性降低，这暗示了经典的糖酵解机制。作为概念证明，我们在昆虫 S2 细胞中复制了这些发现。急性缺氧显着诱导原代血细胞中缺氧诱导因子-1α、GLUT1 和丙酮酸脱氢酶激酶同工酶 1 的表达，并观察到缺氧诱导的葡萄糖摄取和乳酸分泌增加。过剩1体外和体内敲除诱导细胞内活性氧的产生和细胞凋亡，导致虾死亡率增加和大脑中更多的凋亡细胞，这意味着 GLUT1 在缺氧适应中的重要功能。总之，我们的结果表明缺氧介导的糖酵解与血细胞中的 GLUT1 之间存在密切关系。这些结果表明，在甲壳类动物中，对缺氧的适应涉及葡萄糖代谢可塑性。