The L1Tc non-LTR retrotransposon of Trypanosoma cruzi contains an internal RNA-pol II-dependent promoter that strongly activates gene transcription and generates unspliced transcripts

Heras, Sara R.; López, Manuel Carlos; Olivares, Mónica; Thomas, M. Carmen

doi:10.1093/nar/gkl1137

Cited by 28 publications

(49 citation statements)

References 57 publications

(75 reference statements)

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“…The mechanisms to generate mRNAs for non-LTR retrotransposons may imply either the utilization of internal promoters (1–3,5,30) or an HDV-like ribozyme that releases mRNAs from host co-transcripts (19). The HDV-like ribozyme cleaves upstream its catalytic domain and thus both, ribozymes and internal promoters, persist within the mRNAs and their functions are preserved after transposition.…”

Section: Discussionmentioning

confidence: 99%

Identification of an hepatitis delta virus-like ribozyme at the mRNA 5′-end of the L1Tc retrotransposon from Trypanosoma cruzi

Sánchez‐Luque

López

Macías

et al. 2011

Nucleic Acids Research

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L1Tc is a non-LTR LINE element from Trypanosoma cruzi that encodes its transposition machinery and bears an internal promoter. Herewith, we report the identification of an in vitro active hepatitis delta virus-like ribozyme located in the first 77 nt at the 5′-end of the L1Tc mRNA (L1TcRz). The data presented show that L1TcRz has a co-transcriptional function. Using gel-purified uncleaved RNA transcripts, the data presented indicate that the kinetics of the self-cleaving, in a magnesium-dependent reaction, fits to a two-phase decay curve. The cleavage point identified by primer extension takes place at +1 position of the element. The hydroxyl nature of the 5′-end of the 3′-fragment generated by the cleavage activity of L1TcRz was confirmed. Since we have previously described that the 77-nt long fragment located at the 5′-end of L1Tc has promoter activity, the existence of a ribozyme in L1Tc makes this element to be the first described non-LTR retroelement that has an internal promoter–ribozyme dual function. The L1Tc nucleotides located downstream of the ribozyme catalytic motif appear to inhibit its activity. This inhibition may be influenced by the existence of a specific L1Tc RNA conformation that is recognized by RNase P.

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Section: Discussionmentioning

confidence: 99%

Identification of an hepatitis delta virus-like ribozyme at the mRNA 5′-end of the L1Tc retrotransposon from Trypanosoma cruzi

Sánchez‐Luque

López

Macías

et al. 2011

Nucleic Acids Research

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“…on May 11, 2018 by guest http://ec.asm.org/ from other authors (26,42) showing that transcripts of RIME/ingi (T. brucei) and L1Tc (T. cruzi) are unspliced.…”

Section: Vol 6 2007mentioning

confidence: 94%

New Trypanosoma cruzi Repeated Element That Shows Site Specificity for Insertion

et al. 2007

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A new family of site-specific repeated elements identified in Trypanosoma cruzi, which we named TcTREZO, is described here. TcTREZO appears to be a composite repeated element, since three subregions may be defined within it on the basis of sequence similarities with other T. cruzi sequences. Analysis of the distribution of TcTREZO in the genome clearly indicates that it displays site specificity for insertion. Most TcTREZO elements are flanked by conserved sequences. There is a highly conserved 68-bp sequence at the 5 end of the element and a sequence domain of ϳ500 bp without a well-defined borderline at the 3 end. Northern blot hybridization and reverse transcriptase PCR analyses showed that TcTREZO transcripts are expressed as oligo(A)-terminated transcripts whose length corresponds to the unit size of the element (1.6 kb). Transcripts of ϳ0.2 kb derived from a small part of TcTREZO are also detected in steady-state RNA. TcTREZO transcripts are unspliced and not translated. The copy number of TcTREZO sequences was estimated to be ϳ173 copies per haploid genome. TcTREZO appears to have been assembled by insertions of sequences into a progenitor element. Once associated with each other, these subunits were amplified as a new transposable element. TcTREZO shows site specificity for insertion, suggesting that a sequence-specific endonuclease could be responsible for its insertion at a unique site.

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“…The GC-rich SSRs of chromosomes 1 and 3 comprise degenerate retrotransposon transposable elements termed L1Tc and VIPER/SIRE (295), and the GC-rich regions cleaved by etoposide/topoisomerase II bear a centromere function associated with the origin of DNA replication (295). The SSR constitutes transcriptional promoters in which the L1Tc retrotransposon sequences activate gene transcription (46,175).…”

Section: Nuclear Dnamentioning

confidence: 99%

Pathogenesis of Chagas' Disease: Parasite Persistence and Autoimmunity

et al. 2011

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SUMMARY Acute Trypanosoma cruzi infections can be asymptomatic, but chronically infected individuals can die of Chagas' disease. The transfer of the parasite mitochondrial kinetoplast DNA (kDNA) minicircle to the genome of chagasic patients can explain the pathogenesis of the disease; in cases of Chagas' disease with evident cardiomyopathy, the kDNA minicircles integrate mainly into retrotransposons at several chromosomes, but the minicircles are also detected in coding regions of genes that regulate cell growth, differentiation, and immune responses. An accurate evaluation of the role played by the genotype alterations in the autoimmune rejection of self-tissues in Chagas' disease is achieved with the cross-kingdom chicken model system, which is refractory to T. cruzi infections. The inoculation of T. cruzi into embryonated eggs prior to incubation generates parasite-free chicks, which retain the kDNA minicircle sequence mainly in the macrochromosome coding genes. Crossbreeding transfers the kDNA mutations to the chicken progeny. The kDNA-mutated chickens develop severe cardiomyopathy in adult life and die of heart failure. The phenotyping of the lesions revealed that cytotoxic CD45, CD8 + γδ, and CD8α + T lymphocytes carry out the rejection of the chicken heart. These results suggest that the inflammatory cardiomyopathy of Chagas' disease is a genetically driven autoimmune disease.

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The L1Tc non-LTR retrotransposon of Trypanosoma cruzi contains an internal RNA-pol II-dependent promoter that strongly activates gene transcription and generates unspliced transcripts

Cited by 28 publications

References 57 publications

Identification of an hepatitis delta virus-like ribozyme at the mRNA 5′-end of the L1Tc retrotransposon from Trypanosoma cruzi

Identification of an hepatitis delta virus-like ribozyme at the mRNA 5′-end of the L1Tc retrotransposon from Trypanosoma cruzi

New Trypanosoma cruzi Repeated Element That Shows Site Specificity for Insertion

Pathogenesis of Chagas' Disease: Parasite Persistence and Autoimmunity

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