scholarly journals The establishment of variant surface glycoprotein monoallelic expression revealed by single-cell RNA-seq of Trypanosoma brucei in the tsetse fly salivary glands

2021 ◽  
Vol 17 (9) ◽  
pp. e1009904
Author(s):  
Sebastian Hutchinson ◽  
Sophie Foulon ◽  
Aline Crouzols ◽  
Roberta Menafra ◽  
Brice Rotureau ◽  
...  
Keyword(s):  
Gene Expression ◽  
Single Cell ◽  
Salivary Glands ◽  
Trypanosoma Brucei ◽  
Single Molecule ◽  
Single Gene ◽  
Tsetse Fly ◽  
Surface Glycoprotein ◽  
Variant Surface Glycoprotein ◽  
Monoallelic Expression

The long and complex Trypanosoma brucei development in the tsetse fly vector culminates when parasites gain mammalian infectivity in the salivary glands. A key step in this process is the establishment of monoallelic variant surface glycoprotein (VSG) expression and the formation of the VSG coat. The establishment of VSG monoallelic expression is complex and poorly understood, due to the multiple parasite stages present in the salivary glands. Therefore, we sought to further our understanding of this phenomenon by performing single-cell RNA-sequencing (scRNA-seq) on these trypanosome populations. We were able to capture the developmental program of trypanosomes in the salivary glands, identifying populations of epimastigote, gamete, pre-metacyclic and metacyclic cells. Our results show that parasite metabolism is dramatically remodeled during development in the salivary glands, with a shift in transcript abundance from tricarboxylic acid metabolism to glycolytic metabolism. Analysis of VSG gene expression in pre-metacyclic and metacyclic cells revealed a dynamic VSG gene activation program. Strikingly, we found that pre-metacyclic cells contain transcripts from multiple VSG genes, which resolves to singular VSG gene expression in mature metacyclic cells. Single molecule RNA fluorescence in situ hybridisation (smRNA-FISH) of VSG gene expression following in vitro metacyclogenesis confirmed this finding. Our data demonstrate that multiple VSG genes are transcribed before a single gene is chosen. We propose a transcriptional race model governs the initiation of monoallelic expression.

scholarly journals The establishment of variant surface glycoprotein monoallelic expression revealed by single-cell RNA-seq of Trypanosoma brucei in the tsetse fly salivary glands.

2021 ◽  
Author(s):  
Sebastian Hutchinson ◽  
Sophie Foulon ◽  
Aline Crouzols ◽  
Roberta Menafra ◽  
Brice Rotureau ◽  
...  
Keyword(s):  
Gene Expression ◽  
Single Cell ◽  
Salivary Glands ◽  
Trypanosoma Brucei ◽  
In Situ Hybridisation ◽  
Tsetse Fly ◽  
Surface Glycoprotein ◽  
Variant Surface Glycoprotein ◽  
Monoallelic Expression ◽  
Fluorescence In Situ Hybridisation

The long and complex Trypanosoma brucei development in the tsetse fly vector culminates when parasites gain mammalian infectivity in the salivary glands. A key step in this process is the establishment of monoallelic variant surface glycoprotein (VSG) expression and the formation of the VSG coat. The establishment of VSG monoallelic expression is complex and poorly understood, due to the multiple parasite stages present in the salivary glands. Therefore, we sought to further our understanding of this phenomenon by performing single-cell RNA-sequencing (scRNA-seq) on these trypanosome populations. We were able to capture the developmental program of trypanosomes in the salivary glands, identifying populations of epimastigote, gamete, pre-metacyclic and metacyclic cells. Our results show that parasite metabolism is dramatically remodeled during development in the salivary glands, with a shift in transcript abundance from tricarboxylic acid metabolism to glycolytic metabolism. Analysis of VSG gene expression in pre-metacyclic and metacyclic cells revealed a dynamic VSG gene activation program. Strikingly, we found that pre-metacyclic cells contain transcripts from multiple VSG genes, which resolves to singular VSG gene expression in mature metacyclic cells. Single molecule RNA fluorescence in situ hybridisation (smRNA-FISH) of VSG gene expression following in vitro metacyclogenesis confirmed this finding. Our data demonstrate that multiple VSG genes are transcribed before a single gene is chosen. We propose a transcriptional race model governs the initiation of monoallelic expression.

Trypanosoma brucei: posttranscriptional control of the variable surface glycoprotein gene expression site

1989 ◽  
Vol 9 (9) ◽  
pp. 4018-4021
Author(s):  
E Pays ◽  
H Coquelet ◽  
A Pays ◽  
P Tebabi ◽  
M Steinert
Keyword(s):  
Gene Expression ◽  
Trypanosoma Brucei ◽  
Transcription Initiation ◽  
Tsetse Fly ◽  
Surface Glycoprotein ◽  
Insect Vector ◽  
Variable Surface Glycoprotein ◽  
A Genome ◽  
Variable Surface ◽  
Expression Site

The arrest of variable surface glycoprotein (VSG) synthesis is one of the first events accompanying the differentiation of Trypanosoma brucei bloodstream forms into procyclic forms, which are characteristic of the insect vector. This is because of a very fast inhibition of VSG gene transcription which occurs as soon as the temperature is lowered. We report that this effect is probably not controlled at the level of transcription initiation, since the beginning of the VSG gene expression site, about 45 kilobases upstream from the antigen gene, remains transcribed in procyclic forms. The permanent activity of the promoter readily accounts for the systematic reappearance, upon return to the bloodstream form after cyclical transmission, of the antigen type present before passage to the tsetse fly. The abortive transcription of the VSG gene expression site appears linked to RNA processing abnormalities. Such posttranscriptional controls may allow the modulation of gene expression in a genome organized in large multigenic transcription units.

Expression of a retroposon-like sequence upstream of the putative Trypanosoma brucei variant surface glycoprotein gene expression site promoter

1993 ◽  
Vol 13 (11) ◽  
pp. 7036-7044
Author(s):  
M J Lodes ◽  
B L Smiley ◽  
A W Stadnyk ◽  
J L Bennett ◽  
P J Myler ◽  
...  
Keyword(s):  
Gene Expression ◽  
Trypanosoma Brucei ◽  
Copy Number ◽  
Surface Glycoprotein ◽  
Variant Surface Glycoprotein ◽  
Putative Promoter ◽  
Glycoprotein Gene ◽  
Active Expression ◽  
Expression Site ◽  
Total Copy Number

We have cloned the region spanning the putative promoter from two variant surface glycoprotein gene expression sites that are at each end of chromosome M4 of Trypanosoma brucei IsTat 7. Both expression sites contain a retroposon-like sequence (ESR) pseudogene whose 3' end is approximately 30 bp upstream of the putative expression site promoter. The ESRs from both expression sites share considerable sequence homology and are related to LINE-like elements, especially the T. brucei ingi retroposon. Other ESRs are located on large, but not intermediate or mini-, chromosomes in the IsTaR 1 serodeme, and the total copy number is 10 to 20, similar to that estimated for variant surface glycoprotein expression sites. No DNA rearrangements in the vicinity of the ESR and putative expression site promoter were detected following antigenic switches in the IsTaR 1 serodeme. ESR transcripts are present in bloodstream, but not procyclic, forms. Variation in transcript size and sequence between bloodstream variant antigenic types implies that only the ESR from the active expression site is transcribed. This pattern of expression reflects that of sequences downstream of the putative expression site promoter, suggesting that the region of coordinately controlled expression extends upstream of this promoter.

scholarly journals Expression of a retroposon-like sequence upstream of the putative Trypanosoma brucei variant surface glycoprotein gene expression site promoter.

1993 ◽  
Vol 13 (11) ◽  
pp. 7036-7044 ◽  
Author(s):  
M J Lodes ◽  
B L Smiley ◽  
A W Stadnyk ◽  
J L Bennett ◽  
P J Myler ◽  
...  
Keyword(s):  
Gene Expression ◽  
Trypanosoma Brucei ◽  
Copy Number ◽  
Surface Glycoprotein ◽  
Variant Surface Glycoprotein ◽  
Putative Promoter ◽  
Glycoprotein Gene ◽  
Active Expression ◽  
Expression Site ◽  
Total Copy Number

We have cloned the region spanning the putative promoter from two variant surface glycoprotein gene expression sites that are at each end of chromosome M4 of Trypanosoma brucei IsTat 7. Both expression sites contain a retroposon-like sequence (ESR) pseudogene whose 3' end is approximately 30 bp upstream of the putative expression site promoter. The ESRs from both expression sites share considerable sequence homology and are related to LINE-like elements, especially the T. brucei ingi retroposon. Other ESRs are located on large, but not intermediate or mini-, chromosomes in the IsTaR 1 serodeme, and the total copy number is 10 to 20, similar to that estimated for variant surface glycoprotein expression sites. No DNA rearrangements in the vicinity of the ESR and putative expression site promoter were detected following antigenic switches in the IsTaR 1 serodeme. ESR transcripts are present in bloodstream, but not procyclic, forms. Variation in transcript size and sequence between bloodstream variant antigenic types implies that only the ESR from the active expression site is transcribed. This pattern of expression reflects that of sequences downstream of the putative expression site promoter, suggesting that the region of coordinately controlled expression extends upstream of this promoter.

scholarly journals Differential RNA elongation controls the variant surface glycoprotein gene expression sites of Trypanosoma brucei

2000 ◽  
Vol 36 (2) ◽  
pp. 328-340 ◽  
Author(s):  
Luc Vanhamme ◽  
Philippe Poelvoorde ◽  
Annette Pays ◽  
Patricia Tebabi ◽  
Hoang Van Xong ◽  
...  
Keyword(s):  
Gene Expression ◽  
Trypanosoma Brucei ◽  
Surface Glycoprotein ◽  
Variant Surface Glycoprotein ◽  
Glycoprotein Gene
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