Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Nature
2009 May 14;4597244:213-7. doi: 10.1038/nature07997.
Show Gene links
Show Anatomy links
A surface transporter family conveys the trypanosome differentiation signal.
Dean S
,
Marchetti R
,
Kirk K
,
Matthews KR
.
???displayArticle.abstract???
Microbial pathogens use environmental cues to trigger the developmental events needed to infect mammalian hosts or transmit to disease vectors. The parasites causing African sleeping sickness respond to citrate or cis-aconitate (CCA) to initiate life-cycle development when transmitted to their tsetse fly vector. This requires hypersensitization of the parasites to CCA by exposure to low temperature, conditions encountered after tsetse fly feeding at dusk or dawn. Here we identify a carboxylate-transporter family, PAD (proteins associated with differentiation), required for perception of this differentiation signal. Consistent with predictions for the response of trypanosomes to CCA, PAD proteins are expressed on the surface of the transmission-competent 'stumpy-form' parasites in the bloodstream, and at least one member is thermoregulated, showing elevated expression and surface access at low temperature. Moreover, RNA-interference-mediated ablation of PAD expression diminishes CCA-induced differentiation and eliminates CCA hypersensitivity under cold-shock conditions. As well as being molecular transducers of the differentiation signal in these parasites, PAD proteins provide the first example of a surface marker able to discriminate the transmission stage of trypanosomes in their mammalian host.
Figure 2. PAD1 identifies stumpy forms(a) PAD1-expression on methanol-fixed trypanosomes. The slender-cell (‘sl’; identified by having two kinetoplasts, arrowed in the DAPI panel) is PAD1-negative, the stumpy-cell (‘St’) is PAD1-positive. A confocal image of a paraformaldehyde-fixed stumpy-form is also shown (right); peripheral PAD1-labelling (green) is arrowed; nucleus, ‘n’, and kinetoplast, ‘k’, (both stained blue).(b) Quantitation of PAD1 expression on different cell-cycle stages.(c) PAD1-positive cells are those competent to differentiate. Slender and stumpy-forms were methanol-fixed 6hr through differentiation. A slender-morphology PAD1-negative, EP-Procyclin-negative cell is arrowed, other cells are PAD1-positive (red), EP-procyclin-positive (green). Phase-contrast and DAPI images are also shown.(d) Quantitation of the cells expressing PAD1 and/or EP-procyclin. n=500.
Figure 3. PAD2 is cold-inducible(a) PAD protein expression at 37°C or 20°C in stumpy-forms of T. brucei EATRO 2340 or T. brucei AnTat1.1. Samples were stained for all PAD proteins (“Array”), PAD1 or PAD2. α-tubulin controlled for loading.(b) Confocal immunofluorescence-images of paraformaldehyde-fixed stumpy-forms incubated at 37°C or 20°C and co-labelled for α-tubulin (red), PAD2 (green) and DAPI (blue). At 37°C, PAD2 predominantly localised to the flagellar pocket (f.p.; arrowed); at 20°C PAD2 located at the cell surface.(c) Quantitation of the PAD2 location at 37°C or 20°C.
Figure 4. RNAi against all PAD genes reduces differentiation(a) PAD-array expression in parental or PAD-RNAi lines (±doxycycline, D+, D) after 16h at 20°C. Tubulin, loading control.(b) EP-procyclin in Parental (‘P’) and PAD-RNAi stumpy-forms grown ±doxycycline (D+, D−) after 16h at 20°C, then incubated at 27°C with a CA titration. Means (±s.e.m.) of three experiments are shown, as is the % reduction in EP-procyclin in the PAD-RNAi cells compared with parental cells.(c) Flow-cytometry of EP-procyclin expression in PAD-RNAi or parental cells incubated with 0.1mM or 1mM CA. Cold-induced hypersensitivity to CA is ablated in the PAD-RNAi line; at ≥1mM CA both populations differentiate, although this is reduced in the RNAi line. Full flow cytometry data are available in Supplementary Fig. 7.
Barrett,
The trypanosomiases.
2003,
Pubmed
Bass,
The in vitro differentiation of pleomorphic Trypanosoma brucei from bloodstream into procyclic form requires neither intermediary nor short-stumpy stage.
1991,
Pubmed
Billker,
Identification of xanthurenic acid as the putative inducer of malaria development in the mosquito.
1998,
Pubmed
Czichos,
Trypanosoma brucei: cis-aconitate and temperature reduction as triggers of synchronous transformation of bloodstream to procyclic trypomastigotes in vitro.
1986,
Pubmed
Engstler,
Cold shock and regulation of surface protein trafficking convey sensitization to inducers of stage differentiation in Trypanosoma brucei.
2004,
Pubmed
Fang,
Thermoregulation in a parasite's life cycle.
2002,
Pubmed
Fenn,
The cell biology of Trypanosoma brucei differentiation.
2007,
Pubmed
Field,
New approaches to the microscopic imaging of Trypanosoma brucei.
2004,
Pubmed
Hao,
Tsetse immune responses and trypanosome transmission: implications for the development of tsetse-based strategies to reduce trypanosomiasis.
2001,
Pubmed
Hunt,
Studies on compounds promoting the in vitro transformation of Trypanosoma brucei from bloodstream to procyclic forms.
1994,
Pubmed
JACOBS,
DETERMINATION OF CITRIC ACID IN SERUM AND URINE USING BR82.
1964,
Pubmed
Kamsteeg,
MAL decreases the internalization of the aquaporin-2 water channel.
2007,
Pubmed
Kirk,
CD147 is tightly associated with lactate transporters MCT1 and MCT4 and facilitates their cell surface expression.
2000,
Pubmed
Lanham,
Separation of trypanosomes from the blood of infected rats and mice by anion-exchangers.
1968,
Pubmed
Lee,
Fatty acid synthesis by elongases in trypanosomes.
2006,
Pubmed
Lythgoe,
Parasite-intrinsic factors can explain ordered progression of trypanosome antigenic variation.
2007,
Pubmed
Matthews,
Evidence for an interplay between cell cycle progression and the initiation of differentiation between life cycle forms of African trypanosomes.
1994,
Pubmed
McCulloch,
Transformation of monomorphic and pleomorphic Trypanosoma brucei.
2004,
Pubmed
Pusnik,
Pentatricopeptide repeat proteins in Trypanosoma brucei function in mitochondrial ribosomes.
2007,
Pubmed
Saliba,
Sodium-dependent uptake of inorganic phosphate by the intracellular malaria parasite.
2006,
Pubmed
,
Xenbase
Sbicego,
The use of transgenic Trypanosoma brucei to identify compounds inducing the differentiation of bloodstream forms to procyclic forms.
1999,
Pubmed
Shadan,
Microbiology: Signals for change.
2009,
Pubmed
Shapiro,
Analysis by flow cytometry of DNA synthesis during the life cycle of African trypanosomes.
1984,
Pubmed
Sherwin,
The cell division cycle of Trypanosoma brucei brucei: timing of event markers and cytoskeletal modulations.
1989,
Pubmed
Spyropoulos,
TMRPres2D: high quality visual representation of transmembrane protein models.
2004,
Pubmed
Szöor,
Protein tyrosine phosphatase TbPTP1: A molecular switch controlling life cycle differentiation in trypanosomes.
2006,
Pubmed
Tasker,
A novel selection regime for differentiation defects demonstrates an essential role for the stumpy form in the life cycle of the African trypanosome.
2000,
Pubmed
Turner,
Loss of variable antigen during transformation of Trypanosoma brucei rhodesiense from bloodstream to procyclic forms in the tsetse fly.
1988,
Pubmed
Tusnády,
The HMMTOP transmembrane topology prediction server.
2001,
Pubmed
Vassella,
Differentiation of African trypanosomes is controlled by a density sensing mechanism which signals cell cycle arrest via the cAMP pathway.
1997,
Pubmed
Zilberstein,
The role of pH and temperature in the development of Leishmania parasites.
1994,
Pubmed
