Heat-shock disruption of trans-splicing in trypanosomes: effect on Hsp70, Hsp85 and tubulin mRNA synthesis

Muhich, Michael L.; Hsu, M.; Boothroyd, John C.

doi:10.1016/0378-1119(89)90042-5

Cited by 27 publications

(25 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, a severe temperature stress interferes with HSP83 splicing unless the cells are pretreated with a milder stress that prevents this inhibition (10). In trypanosomes, a severe heat shock (42°C) impairs splicing of tubulin transcripts, although HSP70 and HSP83 RNAs are properly matured under these conditions (1,31,32). We now show for L. amazonensis that processing of primary transcripts of HSP70 and HSP83 is more efficient during heat shock.…”

Section: Sequences Within the 201-472 Of The 3ј-utr Are Required For mentioning

confidence: 88%

Developmental Regulation of Heat Shock Protein 83 inLeishmania

Zilka

Garlapati

Dahan

et al. 2001

Journal of Biological Chemistry

View full text Add to dashboard Cite

Developmental gene regulation in trypanosomatids proceeds exclusively by post-transcriptional mechanisms. Stability and abundance of heat shock protein (HSP)70 and HSP83 transcripts in Leishmania increase at mammalian-like temperatures, and their translation is enhanced. Here we report that the 3-untranslated region (UTR) of HSP83 (886 nucleotides) confers the temperature-dependent pattern of regulation on a chloramphenicol acetyltransferase (CAT) reporter transcript. We also show that the majority of the 3-UTR sequences are required for increasing mRNA stability during heat shock. Processing of the HSP70 and HSP83 primary transcripts to poly(A)؉ mRNA was more efficient during heat shock; therefore, even when stability at 33°C was reduced by deletions in the 3-UTR, transcripts still accumulated to comparable and even higher levels. Translation of heat shock transcripts in Leishmania increases dramatically upon temperature elevation. Unlike in other eukaryotes in which the 5-UTR confers preferential translation on heat shock transcripts, we show that translational control of HSP83 in Leishmania originates from its 3-UTR. The 5-UTR alone cannot induce translation during heat shock, but it has a minor contribution when combined with the HSP83 3-UTR. We identified an element located between positions 201 and 472 of the 3-UTR which is essential for increasing translation of the CAT-HSP83 reporter RNA at 33-37°C. This region confers preferential translation during heat shock even in transcripts that were less stable. Thus, investigating the traditionally conserved heat shock response reveals that Leishmania parasites use unique pathways for translational control.Unique and unusual features characterize the genomes of trypanosomatids that comprise an ancient group of eukaryotes. Genes transcribed by RNA polymerase II are found in polycistronic transcription units, and gene clusters repeated in tandem frequently encode abundant proteins. There is no evidence for transcriptional activation of developmentally regulated genes, and mRNA abundance is determined exclusively by post-transcriptional mechanisms. These include differential RNA processing (1) and control of mRNA decay (2-4). Polycistronic transcripts mature by trans-splicing that adds a short capped leader (39-mer) to the 5Ј-end of mRNAs and by 3Ј processing that includes cleavage and polyadenylation. Transsplicing and polyadenylation are coupled mechanistically in trypanosomatids and share regulatory signals that consist of polypyrimidine tracks and potential AG splice sites (5, 6). The 3Ј-untranslated sequences lack the consensus eukaryote AAUAAA signal for cleavage and polyadenylation, and no other consensus element of that nature has been identified.Leishmania parasites exist in the alimentary canal of female sand flies as flagellated promastigotes. They develop into virulent metacyclics that are uniquely adapted for transmission by the fly into a mammalian host where they differentiate into amastigotes, an obligate intracellular life form that resides within ...

show abstract

Section: Sequences Within the 201-472 Of The 3ј-utr Are Required For mentioning

confidence: 88%

Developmental Regulation of Heat Shock Protein 83 inLeishmania

Zilka

Garlapati

Dahan

et al. 2001

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…The transcriptional linkage of the UbEP52 genes is not surprising in light of the previously postulated transcriptional linkage of tandem identical genes in T. brucei (14,26,27,37). Transcriptional linkage of the six genes encoding UbEP52/1, UbEP52/2, EFH5, and calmodulin A, B, and C is significant because two of the genes have a well-identified function.…”

Section: Discussionmentioning

confidence: 87%

“…The intergenic regions described above are similar in size to or shorter than the intergenic regions between housekeeping genes for which polycistronic transcription has been postulated (10,14,26,27,37). Since polycistronic transcription of the calmodulin cluster has been inferred (37), we wished to determine whether the EFH5 gene and the UbEP52 genes are transcribed coordinately with the calmodulin genes.…”

Section: Methodsmentioning

confidence: 99%

Genomic and transcriptional linkage of the genes for calmodulin, EF-hand 5 protein, and ubiquitin extension protein 52 in Trypanosoma brucei.

Wong¹,

Morales²,

Neigel³

et al. 1993

Mol. Cell. Biol.

View full text Add to dashboard Cite

show abstract

“…In T. brucei, HS promotes accumulation of mRNA precursors except for those of the heat shock proteins (Hsps), possibly due to defects in the trans-splicing reaction (44). Using T. cruzi epimastigotes submitted to temperatures of 40°C for 2 h, Nazer and collaborators (45,46) found that most mRNA accumulated in the nucleus, except for mRNAs corresponding to Hsp, which were exported to the cytosol.…”

Section: Resultsmentioning

confidence: 99%

Stress Induces Changes in the Phosphorylation of Trypanosoma cruzi RNA Polymerase II, Affecting Its Association with Chromatin and RNA Processing

2014

View full text Add to dashboard Cite

The phosphorylation of the carboxy-terminal heptapeptide repeats of the largest subunit of RNA polymerase II (Pol II) controls several transcription-related events in eukaryotes. Trypanosomatids lack these typical repeats and display an unusual transcription control. RNA Pol II associates with the transcription site of the spliced leader (SL) RNA, which is used in the trans-splicing of all mRNAs transcribed on long polycistronic units. We found that Trypanosoma cruzi RNA Pol II associated with chromatin is highly phosphorylated. When transcription is inhibited by actinomycin D, the enzyme runs off from SL genes, remaining hyperphosphorylated and associated with polycistronic transcription units. Upon heat shock, the enzyme is dephosphorylated and remains associated with the chromatin. Transcription is partially inhibited with the accumulation of housekeeping precursor mRNAs, except for heat shock genes. DNA damage caused dephosphorylation and transcription arrest, with RNA Pol II dissociating from chromatin although staying at the SL. In the presence of calyculin A, the hyperphosphorylated form detached from chromatin, including the SL loci. These results indicate that in trypanosomes, the unusual RNA Pol II is phosphorylated during the transcription of SL and polycistronic operons. Different types of stresses modify its phosphorylation state, affecting pre-RNA processing.

show abstract

Heat-shock disruption of trans-splicing in trypanosomes: effect on Hsp70, Hsp85 and tubulin mRNA synthesis

Cited by 27 publications

References 21 publications

Developmental Regulation of Heat Shock Protein 83 inLeishmania

Developmental Regulation of Heat Shock Protein 83 inLeishmania

Genomic and transcriptional linkage of the genes for calmodulin, EF-hand 5 protein, and ubiquitin extension protein 52 in Trypanosoma brucei.

Stress Induces Changes in the Phosphorylation of Trypanosoma cruzi RNA Polymerase II, Affecting Its Association with Chromatin and RNA Processing

Contact Info

Product

Resources

About