Molecular control of irreversible bistability during trypanosome developmental commitment.
The life cycle of Trypanosoma brucei involves developmental transitions that allow survival, proliferation, and transmission of these parasites. One of these, the differentiation of growth-arrested stumpy forms in the mammalian blood into insect-stage procyclic forms, can be induced synchronously in vitro with cis-aconitate. Here, we show that this transition is an irreversible bistable switch, and we map the point of commitment to differentiation after exposure to cis-aconitate. This irreversibility implies that positive feedback mechanisms operate to allow commitment (i.e., the establishment of "memory" of exposure to the differentiation signal). Using the reversible translational inhibitor cycloheximide, we show that this signal memory requires new protein synthesis. We further performed stable isotope labeling by amino acids in cell culture to analyze synchronized parasite populations, establishing the protein and phosphorylation profile of parasites pre- and postcommitment, thereby defining the "commitment proteome." Functional interrogation of this data set identified Nek-related kinase as the first-discovered protein kinase controlling the initiation of differentiation to procyclic forms.
Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, Scotland, UK.
Maria Rosa
MR
Domingo-Sananes
Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, Scotland, UK.
Balazs
B
Szöőr
Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK.
Michael A J
MA
Ferguson
Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster LA1 4YG, England, UK m.urbaniak@lancaster.ac.uk keith.matthews@ed.ac.uk.
Michael D
MD
Urbaniak
Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, Scotland, UK m.urbaniak@lancaster.ac.uk keith.matthews@ed.ac.uk.
Keith R
KR
Matthews
D000156:Aconitic Acid / Q000494:pharmacology*; D018797:Cell Cycle Proteins / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D003513:Cycloheximide / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental; D007553:Isotope Labeling; D008018:Life Cycle Stages; D000072380:NIMA-Related Kinase 1; D010766:Phosphorylation; D014176:Protein Biosynthesis / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D020543:Proteome / Q000378:metabolism; D015800:Protozoan Proteins / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013194:Staining and Labeling; D014346:Trypanosoma brucei brucei / Q000166:cytology / Q000235:genetics / Q000254:growth & development*
D018797:Cell Cycle Proteins; D020543:Proteome; D015800:Protozoan Proteins; D000156:Aconitic Acid; D003513:Cycloheximide; D000072380:NIMA-Related Kinase 1; D017346:Protein Serine-Threonine Kinases