Dubois Florence, Caby Stéphanie, Oger Frédérik, Cosseau Céline, Capron Monique, Grunau Christoph, Dissous Colette, Pierce Raymond J
INSERM U 547, Institut Pasteur de Lille, IFR 142, 1 rue du Professeur A. Calmette, Lille, France.
Mol Biochem Parasitol. 2009 Nov;168(1):7-15. doi: 10.1016/j.molbiopara.2009.06.001. Epub 2009 Jun 16.
In order to explore the conservation/divergence of transcriptional regulation in the platyhelminth parasite Schistosoma mansoni, we are studying the structures and functions of transcriptional mediators and in particular histone-modifying enzymes. Reversible histone acetylation changes chromatin structure and modulates gene transcription. The removal of acetyl residues from histones and other proteins is catalyzed by histone deacetylases (HDACs) that are under increasing study as therapeutic targets, both in cancer and parasitic diseases. In order to determine the extent and importance of histone acetylation in S. mansoni, we tested the effects of three histone deacetylase inhibitors (HDACi) on both larval and adult worms in culture. Trichostatin A (TSA), valproic acid (VPA) and suberoylanilide hydroxamic acid (SAHA) inhibited global HDAC activity at all life-cycle stages. TSA and VPA, but not SAHA, caused mortality of schistosomula and adults, with TSA showing the most rapid effect. Moreover, TSA caused an increase in apoptosis in schistosomula shown by the TUNEL assay and an increase in caspase 3/7 activity. Both TSA and VPA were shown to cause an increase in general levels of protein acetylation in schistosomes; more particularly of histone 4 whereas histone 3 acetylation was less affected. In the case of TSA treatment this histone hyperacetylation was correlated with the increased expression of caspases 3 and 7 transcripts. Finally, quantitative chromatin immunoprecipitation showed that the proximal promoter region of the S. mansoni caspase 7 gene was hyperacetylated on histone H4 after TSA treatment.
为了探究曼氏血吸虫这种扁形虫寄生虫转录调控的保守性/差异性，我们正在研究转录中介体尤其是组蛋白修饰酶的结构和功能。可逆的组蛋白乙酰化改变染色质结构并调节基因转录。组蛋白脱乙酰酶（HDACs）催化组蛋白和其他蛋白质上乙酰残基的去除，目前它们作为癌症和寄生虫病的治疗靶点受到越来越多的研究。为了确定组蛋白乙酰化在曼氏血吸虫中的程度和重要性，我们测试了三种组蛋白脱乙酰酶抑制剂（HDACi）对培养中的幼虫和成虫的影响。曲古抑菌素A（TSA）、丙戊酸（VPA）和辛二酰苯胺异羟肟酸（SAHA）在所有生命周期阶段均抑制总体HDAC活性。TSA和VPA，但不是SAHA，导致童虫和成虫死亡，TSA显示出最快的效果。此外，TUNEL检测显示TSA导致童虫凋亡增加，且半胱天冬酶3/7活性增加。TSA和VPA均显示导致血吸虫中蛋白质乙酰化总体水平增加；更特别的是组蛋白4的乙酰化增加，而组蛋白3的乙酰化受影响较小。在TSA处理的情况下，这种组蛋白高乙酰化与半胱天冬酶3和7转录本表达增加相关。最后，定量染色质免疫沉淀显示，TSA处理后，曼氏血吸虫半胱天冬酶7基因的近端启动子区域在组蛋白H4上发生高乙酰化。
