Transcription rate modulation through the Trypanosoma cruzi life cycle occurs in parallel with changes in nuclear organisation
Transcription rate modulation through the Trypanosoma cruzi life cycle occurs in parallel with changes in nuclear organisation
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DOI：
10.1016/s0166-6851(00)00349-2
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发表时间：
2001-01-15
影响因子：
1.5
通讯作者：
Schenkman, S
中科院分区：
文献类型：
--
作者：
Elias, MCQB;Marques-Porto, R;Schenkman, S
在锥虫中，转录作为大的多顺反子单位发生，反式剪接和多聚腺苷酸化产生每个单独的mRNA。没有明确的RNA。聚合酶II启动子和mRNA稳定化最有可能是控制差异表达mRNA水平的过程，因为甚至没有报道在转录水平上选择性调节基因活性。在这里，我们显示了大量的RNA聚合酶I和II的转录率下降时，增殖形式的克氏锥虫（epimastigotes和无鞭毛体）转化为非增殖和感染的形式（锥鞭毛体）。我们还表明，这些转录的变化发生在平行的核结构的修改。而增殖型的细胞核是圆形的，含有少量的外周异染色质和一个大的核仁，锥鞭毛体的细胞核是细长的，核仁消失，异染色质占据了大部分的核室。转录的减少与核仁解体平行，如核仁抗原的分散所见。作为T. Cruzi通过增殖和感染形式连续循环，该系统可以揭示涉及控制核组织和染色质重塑的分子机制。(C)2001 Elsevier Science B.V.保留所有权利。
In trypanosomes transcription occurs as large polycistronic units, with trans-splicing and polyadenylation generating each individual mRNA. There are no defined RNA. polymerase II promoters and mRNA stabilisation is most likely the process controlling levels of differentially expressed mRNAs, since no selective modulation of gene activity has even been reported at the transcriptional level. Here, we show a large decrease in the transcription rates by RNA polymerases I and II when proliferative forms of Trypanosoma cruzi (epimastigotes and amastigotes) transform into non-proliferative and infective forms (trypomastigotes). We also show that these changes in transcription occur in parallel with modifications in the nuclear structure. While nuclei of proliferative forms are round, contain small amounts of peripheral heterochromatin and a large nucleolus, nuclei of trypomastigotes are elongated, the nucleolus disappears and the heterochromatin occupies most of the nuclear compartment. The decrease in the transcription parallels the nucleolus disassembly, as seen by the dispersion of nucleolar antigens. As T. cruzi cycles continuously through proliferative and infective forms, the molecular mechanisms involved in the control of nuclear organisation and chromatin remodelling can be revealed by this system. (C) 2001 Elsevier Science B.V. All rights reserved.