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TLR9 activation is triggered by the excess of stimulatory versus inhibitory motifs present in Trypanosomatidae DNA.

Khan ME, Borde C, Rocha EP, Mériaux V, Maréchal V, Escoll P, Goyard S, Cavaillon JM, Manoury B, Doyen N - PLoS Negl Trop Dis (2014)

Bottom Line: Here we found that the DC-targeting immunostimulatory property of Leishmania major DNA is shared by other Trypanosomatidae DNA, suggesting that this is a general trait of these eukaryotic single-celled parasites.Interestingly, this contrasting features between L. major and vertebrate genomes in the frequency of these motifs are shared by other Trypanosomatidae genomes (Trypanosoma cruzi, brucei and vivax).We also addressed the possibility that proteins expressed in DCs could interact with DNA and promote TLR9 activation.

View Article: PubMed Central - PubMed

Affiliation: Institut Pasteur, Département Infection et Epidémiologie, Unité Cytokines & Inflammation, Paris, France.

ABSTRACT
DNA sequences purified from distinct organisms, e.g. non vertebrate versus vertebrate ones, were shown to differ in their TLR9 signalling properties especially when either mouse bone marrow-derived- or human dendritic cells (DCs) are probed as target cells. Here we found that the DC-targeting immunostimulatory property of Leishmania major DNA is shared by other Trypanosomatidae DNA, suggesting that this is a general trait of these eukaryotic single-celled parasites. We first documented, in vitro, that the low level of immunostimulatory activity by vertebrate DNA is not due to its limited access to DCs' TLR9. In addition, vertebrate DNA inhibits the activation induced by the parasite DNA. This inhibition could result from the presence of competing elements for TLR9 activation and suggests that DNA from different species can be discriminated by mouse and human DCs. Second, using computational analysis of genomic DNA sequences, it was possible to detect the presence of over-represented inhibitory and under-represented stimulatory sequences in the vertebrate genomes, whereas L. major genome displays the opposite trend. Interestingly, this contrasting features between L. major and vertebrate genomes in the frequency of these motifs are shared by other Trypanosomatidae genomes (Trypanosoma cruzi, brucei and vivax). We also addressed the possibility that proteins expressed in DCs could interact with DNA and promote TLR9 activation. We found that TLR9 is specifically activated with L. major HMGB1-bound DNA and that HMGB1 preferentially binds to L. major compared to mouse DNA. Our results highlight that both DNA sequence and vertebrate DNA-binding proteins, such as the mouse HMGB1, allow the TLR9-signaling to be initiated and achieved by Trypanosomatidae DNA.

No MeSH data available.


Related in: MedlinePlus

The representation of stimulatory and inhibitory motifs in L. major genome is shared by other Trypanosomatidae genomes.The data represent the ratio of observed/expected number rO/E for each motif [stimulatory (RRCGYY and HRWCGTTN) or inhibitory (WKKVGGGG and CCNDDNNGGG)] from the analysis of Trypanosomatidae complete genomes (Table 1). The dotted line represent the ratio of observed/expected rO/E sequences which is 1, when no selection pressure is exerted on the genome in a neutral environment.
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pntd-0003308-g007: The representation of stimulatory and inhibitory motifs in L. major genome is shared by other Trypanosomatidae genomes.The data represent the ratio of observed/expected number rO/E for each motif [stimulatory (RRCGYY and HRWCGTTN) or inhibitory (WKKVGGGG and CCNDDNNGGG)] from the analysis of Trypanosomatidae complete genomes (Table 1). The dotted line represent the ratio of observed/expected rO/E sequences which is 1, when no selection pressure is exerted on the genome in a neutral environment.

Mentions: We wondered whether these observations could be extended from L. major to other Trypanosomatidae DNA. The ratios rO/E for both stimulatory motifs RRCGYY and HRWCGTTN are identical and reach 1.1, 0.8, 0.9 respectively in L. major, T. cruzi and T. brucei; for T. vivax the ratios are 0.68 and 0.91 (Figure 7 and Table 1). However, these ratios are always higher in Trypanosomatidae genomes than in vertebrate genomes. In contrast, the ratio of the two inhibitory motifs is more variable between Trypanosomatidae genomes. The ratios are between 0.3 and 0.9 for L. major, T. cruzi and T. vivax genome and slightly higher than 1 only for T. brucei.


TLR9 activation is triggered by the excess of stimulatory versus inhibitory motifs present in Trypanosomatidae DNA.

Khan ME, Borde C, Rocha EP, Mériaux V, Maréchal V, Escoll P, Goyard S, Cavaillon JM, Manoury B, Doyen N - PLoS Negl Trop Dis (2014)

The representation of stimulatory and inhibitory motifs in L. major genome is shared by other Trypanosomatidae genomes.The data represent the ratio of observed/expected number rO/E for each motif [stimulatory (RRCGYY and HRWCGTTN) or inhibitory (WKKVGGGG and CCNDDNNGGG)] from the analysis of Trypanosomatidae complete genomes (Table 1). The dotted line represent the ratio of observed/expected rO/E sequences which is 1, when no selection pressure is exerted on the genome in a neutral environment.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4230925&req=5

pntd-0003308-g007: The representation of stimulatory and inhibitory motifs in L. major genome is shared by other Trypanosomatidae genomes.The data represent the ratio of observed/expected number rO/E for each motif [stimulatory (RRCGYY and HRWCGTTN) or inhibitory (WKKVGGGG and CCNDDNNGGG)] from the analysis of Trypanosomatidae complete genomes (Table 1). The dotted line represent the ratio of observed/expected rO/E sequences which is 1, when no selection pressure is exerted on the genome in a neutral environment.
Mentions: We wondered whether these observations could be extended from L. major to other Trypanosomatidae DNA. The ratios rO/E for both stimulatory motifs RRCGYY and HRWCGTTN are identical and reach 1.1, 0.8, 0.9 respectively in L. major, T. cruzi and T. brucei; for T. vivax the ratios are 0.68 and 0.91 (Figure 7 and Table 1). However, these ratios are always higher in Trypanosomatidae genomes than in vertebrate genomes. In contrast, the ratio of the two inhibitory motifs is more variable between Trypanosomatidae genomes. The ratios are between 0.3 and 0.9 for L. major, T. cruzi and T. vivax genome and slightly higher than 1 only for T. brucei.

Bottom Line: Here we found that the DC-targeting immunostimulatory property of Leishmania major DNA is shared by other Trypanosomatidae DNA, suggesting that this is a general trait of these eukaryotic single-celled parasites.Interestingly, this contrasting features between L. major and vertebrate genomes in the frequency of these motifs are shared by other Trypanosomatidae genomes (Trypanosoma cruzi, brucei and vivax).We also addressed the possibility that proteins expressed in DCs could interact with DNA and promote TLR9 activation.

View Article: PubMed Central - PubMed

Affiliation: Institut Pasteur, Département Infection et Epidémiologie, Unité Cytokines & Inflammation, Paris, France.

ABSTRACT
DNA sequences purified from distinct organisms, e.g. non vertebrate versus vertebrate ones, were shown to differ in their TLR9 signalling properties especially when either mouse bone marrow-derived- or human dendritic cells (DCs) are probed as target cells. Here we found that the DC-targeting immunostimulatory property of Leishmania major DNA is shared by other Trypanosomatidae DNA, suggesting that this is a general trait of these eukaryotic single-celled parasites. We first documented, in vitro, that the low level of immunostimulatory activity by vertebrate DNA is not due to its limited access to DCs' TLR9. In addition, vertebrate DNA inhibits the activation induced by the parasite DNA. This inhibition could result from the presence of competing elements for TLR9 activation and suggests that DNA from different species can be discriminated by mouse and human DCs. Second, using computational analysis of genomic DNA sequences, it was possible to detect the presence of over-represented inhibitory and under-represented stimulatory sequences in the vertebrate genomes, whereas L. major genome displays the opposite trend. Interestingly, this contrasting features between L. major and vertebrate genomes in the frequency of these motifs are shared by other Trypanosomatidae genomes (Trypanosoma cruzi, brucei and vivax). We also addressed the possibility that proteins expressed in DCs could interact with DNA and promote TLR9 activation. We found that TLR9 is specifically activated with L. major HMGB1-bound DNA and that HMGB1 preferentially binds to L. major compared to mouse DNA. Our results highlight that both DNA sequence and vertebrate DNA-binding proteins, such as the mouse HMGB1, allow the TLR9-signaling to be initiated and achieved by Trypanosomatidae DNA.

No MeSH data available.


Related in: MedlinePlus