The expression of lactate dehydrogenase is important for the cell cycle of Toxoplasma gondii
The expression of lactate dehydrogenase is important for the cell cycle of Toxoplasma gondii
复制标题
DOI：
10.1074/jbc.m409175200
复制
发表时间：
2004-12-10
影响因子：
4.8
通讯作者：
Ananvoranich, S
中科院分区：
文献类型：
--
作者：
Al-Anouti, F;Tomavo, S;Ananvoranich, S
在弓形虫中，乳酸脱氢酶由两个独立的发育调控基因LDH1和LDH2编码。这些基因及其产物与寄生虫分化过程中代谢流的控制有关。为了研究LDH1和LDH2在这一过程中的意义，我们建立了稳定的转基因寄生虫系，其中这两种乳酸脱氢酶亚型的表达以阶段特异性的方式被下调。与亲本寄生虫相比，这些LDH基因敲除寄生虫在速殖子和缓殖子阶段都表现出不同的生长速度。当寄生虫在体外条件下生长时，其分化过程受到损害。在小鼠模型系统中的活体研究表明，这些寄生虫系的速殖子不能形成大量的组织包囊，也不能建立慢性感染。最重要的是，最初感染四种LDH基因敲除品系中任何一种的速殖子的所有小鼠在随后与亲本寄生虫的速殖子(104)的攻击中存活下来，这一剂量通常会导致100%的死亡，这表明用LDH基因敲除的速殖子活疫苗可以提供对弓形虫的保护。因此，我们得出结论，LDH的表达对寄生虫的分化是必不可少的。LDH1和LDH2表达的下调导致了毒力减弱的寄生虫，这些寄生虫在慢性感染的小鼠模型中无法表现出显著的脑囊肿负担。
In Toxoplasma gondii, lactate dehydrogenase is encoded by two independent and developmentally regulated genes LDH1 and LDH2. These genes and their products have been implicated in the control of a metabolic flux during parasite differentiation. To investigate the significance of LDH1 and LDH2 in this process, we generated stable transgenic parasite lines in which the expression of these two expressed isoforms of lactate dehydrogenase was knocked down in a stage-specific manner. These LDH knockdown parasites exhibited variable growth rates in either the tachyzoite or the bradyzoite stage, as compared with the parental parasites. Their differentiation processes were impaired when the parasites were grown under in vitro conditions. In vivo studies in a murine model system revealed that tachyzoites of these parasite lines were unable to form significant numbers of tissue cysts and to establish a chronic infection. Most importantly, all mice that were initially infected with tachyzoites of either of the four LDH knockdown lines survived a subsequent challenge with tachyzoites of the parental parasites ( 104), a dose that usually causes 100% mortality, suggesting that live vaccination of mice with the LDH knockdown tachyzoites can confer protection against T. gondii. Thus, we conclude that LDH expression is essential for parasite differentiation. The knockdown of LDH1 and LDH2 expression gave rise to virulence-attenuated parasites that were unable to exhibit a significant brain cyst burden in a murine model of chronic infection.