Stimuli of differentiation regulate RNA elongation in the transcription units for the major stage-specific antigens of Trypanosoma brucei

• Published in: Nucleic acids research 1995-06, Vol.23 (11), p.1862-1869
• Main Authors: Vanhamme, Luc, Berberof, Magali, Le Ray, Dominique, Pays, Etienne
• Format: Article
• Language: English
• Subjects: Animals; Gene Expression Regulation; Membrane Glycoproteins - genetics; Membrane Glycoproteins - metabolism; Protozoan Proteins; RNA, Messenger - genetics; RNA, Messenger - metabolism; Transcription, Genetic; Trypanosoma brucei; Trypanosoma brucei brucei - genetics; Trypanosoma brucei brucei - metabolism
• ISSN: 0305-1048; 1362-4962
• DOI: 10.1093/nar/23.11.1862

In Trypanosoma brucel, the mutually exclusive expression of the major surface antigens, the variant surface glycoprotein (VSG) of the bloodstream form and procyclin of the procyclic form, is due to a stage-specific accumulation of the respective mRNAs. Through the targeting of a reporter construct in the procyclin promoter region, we show that independently of any selection pressure, a relatively high level of transcription (~10%) occurs from the procyclin promoter in the bloodstream form. This transcription leads to the production of detectable amounts of polyadenylated mRNAs. However, RNA elongation In the procyclin transcription unit is down-regulated at this stage. Transcription elongation In the procyclin and VSG units Is inversely controlled by the combination of factors which cause the differentiation of bloodstream into procyclic forms in vitro These factors include temperature, crtrate/cls-aconltate and the incubation medium. Our results suggest that inverse regulations of primary transcription in the VSG and procyclin units are early events that underiy the differentiation of the parasite.