Center for Infection and Immunity of Lillle, CNRS UMR 8204, INSERM U 1019, Université Lille Nord de France, Institut Pasteur de Lille, Lille, France.
PLoS One. 2012;7(3):e32671. doi: 10.1371/journal.pone.0032671. Epub 2012 Mar 9.
Apicomplexan parasites are responsible for some of the most deadly parasitic diseases afflicting humans, including malaria and toxoplasmosis. These obligate intracellular parasites exhibit a complex life cycle and a coordinated cell cycle-dependant expression program. Their cell division is a coordinated multistep process. How this complex mechanism is organised remains poorly understood.
In this study, we provide evidence for a link between heterochromatin, cell division and the compartmentalisation of the nucleus in Toxoplasma gondii. We characterised a T. gondii chromodomain containing protein (named TgChromo1) that specifically binds to heterochromatin. Using ChIP-on-chip on a genome-wide scale, we report TgChromo1 enrichment at the peri-centromeric chromatin. In addition, we demonstrate that TgChromo1 is cell-cycle regulated and co-localised with markers of the centrocone. Through the loci-specific FISH technique for T. gondii, we confirmed that TgChromo1 occupies the same nuclear localisation as the peri-centromeric sequences.
We propose that TgChromo1 may play a role in the sequestration of chromosomes at the nuclear periphery and in the process of T. gondii cell division.
顶复门寄生虫是导致一些最致命的人类寄生虫病的元凶，包括疟疾和弓形体病。这些专性细胞内寄生虫表现出复杂的生命周期和协调的细胞周期依赖表达程序。它们的细胞分裂是一个协调的多步骤过程。这个复杂机制是如何组织的仍然知之甚少。
在这项研究中，我们提供了证据表明，在刚地弓形虫中，异染色质、细胞分裂和核的区室化之间存在联系。我们鉴定了一种含有染色质结构域的刚地弓形虫蛋白（命名为 TgChromo1），它能特异性地结合异染色质。通过在全基因组范围内进行 ChIP-on-chip 实验，我们报告了 TgChromo1 在着丝粒周围染色质上的富集。此外，我们证明 TgChromo1 是细胞周期调控的，并与中心体标志物共定位。通过针对刚地弓形虫的特异性荧光原位杂交（FISH）技术，我们证实 TgChromo1 占据与着丝粒周围序列相同的核定位。
我们提出 TgChromo1 可能在染色体被隔离到核周以及刚地弓形虫细胞分裂过程中发挥作用。
