Queiroz Rafael, Benz Corinna, Fellenberg Kurt, Hoheisel Jörg D, Clayton Christine
Zentrum für Molekulare Biologie der Universität Heidelberg, ZMBH-DKFZ Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany.
BMC Genomics. 2009 Oct 26;10:495. doi: 10.1186/1471-2164-10-495.
Trypanosome gene expression is regulated almost exclusively at the post-transcriptional level, with mRNA degradation playing a decisive role. When trypanosomes are transferred from the blood of a mammal to the midgut of a Tsetse fly, they transform to procyclic forms: gene expression is reprogrammed, changing the cell surface and switching the mode of energy metabolism. Within the blood, trypanosomes can pre-adapt for Tsetse transmission, becoming growth-arrested stumpy forms. We describe here the transitions in gene expression that occur during differentiation of in-vitro cultured bloodstream forms to procyclic forms.
Some mRNAs showed changes within 30 min of cis-aconitate addition, whereas others responded 12-24 hours later. For the first 12 h after addition of cis-aconitate, cells accumulated at the G1 phase of the cell cycle, and showed decreases in mRNAs required for proliferation, mimicking the changes seen in stumpy forms: many mRNAs needed for ribosomal and flagellar biogenesis showed striking co-regulation. Other mRNAs encoding components of signal transduction pathways and potential regulators were specifically induced only during differentiation. Messenger RNAs encoding proteins required for individual metabolic pathways were often co-regulated.
Trypanosome genes form post-transcriptional regulons in which mRNAs with functions in particular pathways, or encoding components of protein complexes, show almost identical patterns of regulation.
锥虫的基因表达几乎完全在转录后水平受到调控，其中mRNA降解起决定性作用。当锥虫从哺乳动物血液转移到采采蝇的中肠时，它们会转变为前循环形式：基因表达被重新编程，改变细胞表面并转换能量代谢模式。在血液中，锥虫可以为采采蝇传播进行预适应，变成生长停滞的粗短型。我们在此描述体外培养的血流形式向前循环形式分化过程中发生的基因表达转变。
一些mRNA在添加顺乌头酸酯后30分钟内就出现变化，而其他的则在12 - 24小时后才有反应。在添加顺乌头酸酯后的前12小时，细胞在细胞周期的G1期积累，并显示出增殖所需mRNA的减少，这与粗短型中观察到的变化相似：许多核糖体和鞭毛生物发生所需的mRNA表现出显著的共同调控。其他编码信号转导途径成分和潜在调节因子的mRNA仅在分化过程中被特异性诱导。编码各个代谢途径所需蛋白质的信使RNA常常共同受到调控。
锥虫基因形成转录后调控子，其中在特定途径中具有功能或编码蛋白质复合物成分的mRNA表现出几乎相同的调控模式。
