MOLECULAR MECHANISM OF MALARIA PATHOGENESIS: REGULATION OF TRANSCRIPTIONAL CONTRO

人类疟疾寄生虫恶性疟原虫有一个复杂的生活史，在蚊媒和人类宿主中都有不同形态的发育阶段。寄生虫的发育和分化与不同的基因表达模式相一致。为了了解恶性疟原虫如何调节其基因表达，我们克隆了编码组蛋白脱乙酰酶(PfHDAC)的恶性疟原虫基因，PfHDAC是参与组蛋白蛋白修饰及其在染色质内相互作用的关键转录调节因子。PfHDAC与哺乳动物组蛋白脱乙酰酶的同源性约为50%。而且，像大多数哺乳动物酶一样，这种蛋白主要在成熟寄生虫的细胞核中表达。最近，针对哺乳动物组蛋白脱乙酰酶的药物被证明对包括疟原虫在内的顶端复合体原生动物具有抑制活性。随着疟疾原虫耐药性的普遍存在，恶性疟原虫中该蛋白的鉴定对于未来疟疾新疗法的开发具有重要意义。我们目前正在表达这种酶，以用于进一步的生化特性和药物筛选。由于该基因在寄生虫生命周期中的特定表达，我们针对该基因进行干扰，以使弱化的寄生虫成为寄生虫。基因破坏是通过与PfHDAC基因同源重组创建零突变来实现的。突变的寄生虫将在生化、形态和传染性方面进行特征分析。

Human malaria parasite, Plasmodium falciparum, has a complex life cycle, which involves the developemnt of various morphologically distinct stages in both mosquito vector and human host. Development and differentiation of the parasite coincides with expression of different pattern of gene expression. To understand how the parasite regulates its gene expression, we have cloned the P. falciparum gene encoding histone deacetylase (PfHDAC), a key transcription modulator involved in the modification of histone proteins and their interaction within chromatin. PfHDAC shows about 50% homology with mammalian histone deacetylases. And, like most of the mammalian enzymes, this protein is expressed mainly in the nucleus of mature parasites. Recently the drugs targeting mammalian histone deacetylases were shown to exhibit the inhibitory activity against apicomplexa protozoan including Plasmodium spp. With the widespread of drug resistance in malaria parasites, identification of this protein in P. falciparum is critical for the future development of novel therapeutics against malaria parasites. We're currently expressing this enzyme for further biochemical characterization and drug screening. Because of the specific expression of this gene during parasite life cycle, we are targeting this gene for disruption in order to make an attenauted a parasite. The gene disruption is being achieved by homologous recombination with PfHDAC gene to create a null mutant. The mutant parasites will be characterized biochemically, morphologically, and for infectivity.