Larreta Ruth, Soto Manuel, Quijada Luis, Folgueira Cristina, Abanades Daniel R, Alonso Carlos, Requena Jose M
Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid, 28049, Spain.
BMC Mol Biol. 2004 Jun 3;5:3. doi: 10.1186/1471-2199-5-3.
Exposure of Leishmania promastigotes to the temperature of their mammalian hosts results in the induction of a typical heat shock response. It has been suggested that heat shock proteins play an important role in parasite survival and differentiation.
Here we report the studies on the expression of the heat shock protein 83 (HSP83) genes of Leishmania infantum. Confirming previous observations for other Leishmania species, we found that the L. infantum HSP83 transcripts also show a temperature-dependent accumulation that is controlled by a post-transcriptional mechanism involving sequences located in the 3'-untranslated region (3'-UTR). However, contrary to that described for L. amazonensis, the accumulation of the HSP83 transcripts in L. infantum is dependent on active protein synthesis. The translation of HSP83 transcripts is enhanced during heat shock and, as first described in L. amazonensis, we show that the 3'-UTR of the L. infantum HSP83 gene is essential for this translational control. Measurement of the steady-state levels of HSP83 transcripts along the promastigote-to-amastigote differentiation evidenced a specific profile of HSP83 RNAs: after an initial accumulation of HSP83 transcripts observed short after (2 h) incubation in the differentiation conditions, the amount of HSP83 RNA decreased to a steady-state level lower than in undifferentiated promastigotes. We show that this transient accumulation is linked to the presence of the 3'-UTR and flanking regions. Again, an 8-fold increase in translation of the HSP83 transcripts is observed short after the initiation of the axenic differentiation, but it is not sustained after 9 h.
This transient expression of HSP83 genes could be relevant for the differentiation of Leishmania, and the underlying regulatory mechanism may be part of the developmental program of this parasite.
利什曼原虫前鞭毛体暴露于其哺乳动物宿主的温度下会诱导典型的热休克反应。有人提出热休克蛋白在寄生虫的存活和分化中起重要作用。
在此我们报告了对婴儿利什曼原虫热休克蛋白83（HSP83）基因表达的研究。正如之前对其他利什曼原虫物种的观察结果所证实的那样，我们发现婴儿利什曼原虫HSP83转录本也呈现出温度依赖性积累，这种积累受一种转录后机制控制，该机制涉及位于3'非翻译区（3'-UTR）的序列。然而，与亚马逊利什曼原虫的情况相反，婴儿利什曼原虫中HSP83转录本的积累依赖于活跃的蛋白质合成。HSP83转录本的翻译在热休克期间增强，并且正如首次在亚马逊利什曼原虫中所描述的那样，我们表明婴儿利什曼原虫HSP83基因的3'-UTR对于这种翻译控制至关重要。沿着前鞭毛体到无鞭毛体的分化过程测量HSP83转录本的稳态水平，显示出HSP83 RNA的特定谱型：在分化条件下孵育后不久（2小时）观察到HSP83转录本最初积累之后，HSP83 RNA的量下降到低于未分化前鞭毛体的稳态水平。我们表明这种短暂积累与3'-UTR和侧翼区域的存在有关。同样，在无菌分化开始后不久观察到HSP83转录本的翻译增加了8倍，但在9小时后并未持续。
HSP83基因的这种短暂表达可能与利什曼原虫的分化相关，其潜在的调控机制可能是该寄生虫发育程序的一部分。
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