Toxoplasma gondii rapidly propagates through endodyogeny of tachyzoites, a process in which daughter parasites divide within the cell of the mother parasite. Recent studies have revealed that transcription factors with AP2‐domain participate in the process of cell division in T. gondii. However, the concise regulation of the division cycles by AP2 proteins is poorly understood. In this study, we evaluated the effect of the transcription factor TgAP2IX‐5 on the daughter cell formation in T. gondii. TgAP2IX‐5 is a nuclear protein and is highly expressed during the S phase of the cell cycle of tachyzoites. TgAP2IX‐5‐disrupted strain showed a severe defect in replication and completely blocked lytic parasite growth. Following 3‐indoleacetic acid treatment or without treatment of AP2IX‐5‐AID‐3HA tagged strain for 30 min, 1 and 2 hr, the differentially expressed genes were 8, 54 and 202, respectively. Among these genes, the significantly downregulated ones were AP2 proteins, inner membrane complex (IMC) proteins and SAG‐related proteins. Interestingly, loss of TgAP2IX‐5 leads to a defect in internal daughter IMC formation and abnormalities in the morphology of organelles during cell division. Together, our study suggests that TgAP2IX‐5 is crucial in regulating IMC formation of daughter cells in T. gondii.

中文翻译：

---

弓形虫速殖子的内部子体形成由转录因子 TgAP2IX-5 协调

弓形虫通过速殖子的内源性快速繁殖，这是一种子寄生虫在母寄生虫细胞内分裂的过程。最近的研究表明，具有 AP2 结构域的转录因子参与了弓形虫的细胞分裂过程。然而，人们对 AP2 蛋白对分裂周期的简明调控知之甚少。在这项研究中，我们评估了转录因子 TgAP2IX-5 对弓形虫子细胞形成的影响. TgAP2IX-5 是一种核蛋白，在速殖子细胞周期的 S 期高表达。TgAP2IX-5 破坏的菌株显示出严重的复制缺陷并完全阻止了裂解性寄生虫的生长。在 3-吲哚乙酸处理或不处理 AP2IX-5-AID-3HA 标记菌株 30 分钟、1 和 2 小时后，差异表达的基因分别为 8、54 和 202。在这些基因中，显着下调的是 AP2 蛋白、内膜复合物 (IMC) 蛋白和 SAG 相关蛋白。有趣的是，TgAP2IX-5 的缺失导致内部子代 IMC 形成的缺陷和细胞分裂过程中细胞器形态的异常。总之，我们的研究表明 TgAP2IX-5 在调节弓形虫子细胞 IMC 形成中至关重要。