Trypanosoma brucei: reduction of GPI-phospholipase C protein during differentiation is dependent on replication of newly transformed cells.
The protozoan parasite Trypanosoma brucei lives in the bloodstream of vertebrates or in a tsetse fly. Expression of a GPI-phospholipase C polypeptide (GPI-PLCp) in the parasite is restricted to the bloodstream form. Events controlling the amount of GPI-PLCp expressed during differentiation are not completely understood. Our metabolic "pulse-chase" analysis reveals that GPI-PLCp is stable in bloodstream form. However, during differentiation of bloodstream to insect stage (procyclic) T. brucei, translation GPI-PLC mRNA ceases within 8h of initiating transformation. GPI-PLCp is not lost precipitously from newly transformed procyclic trypanosomes. Nascent procyclics contain 400-fold more GPI-PLCp than established insect stage T. brucei. Reduction of GPI-PLCp in early-stage procyclics is linked to parasite replication. Sixteen cell divisions are required to reduce the amount of GPI-PLCp in newly differentiated procyclics to levels present in the established procyclic. GPI-PLCp is retained in strains of T. brucei that fail to replicate after differentiation of the bloodstream to the procyclic form. Thus, at least two factors control levels of GPI-PLCp during differentiation of bloodstream T. brucei; (i) repression of GPI-PLC mRNA translation, and (ii) sustained replication of newly transformed procyclic T. brucei. These studies illustrate the importance of repeated cell divisions in controlling the steady-state amount of GPI-PLCp during differentiation of the African trypanosome.
Subramanya
Sandesh
S
Department of Cellular Biology, The University of Georgia, 724 Biological Sciences, Athens, GA 30602, USA.
Armah
Dora A
DA
Mensa-Wilmot
Kojo
K
D000818:Animals; D002461:Cell Line, Transformed; D054800:Glycosylphosphatidylinositol Diacylglycerol-Lyase / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D014170:Transformation, Genetic; D014346:Trypanosoma brucei brucei / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*
D012333:RNA, Messenger; D054800:Glycosylphosphatidylinositol Diacylglycerol-Lyase