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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

Selection for inhibitory and against stimulatory TLR9 motifs in vertebrate genome.(A) Poly G8 (GGGG)2, stimulatory GACGTT and inhibitory TTAGGG motifs were quantified in L. major and mouse genomes. Stimulatory GTCGTT motif was quantified in L. major and human genomes. The datas are represented as copy number per 106 bases pair ( = copy number/genome size (bp)*106). (B) Stimulatory (RRCGYY and HRWCGTTN) and inhibitory (WKKVGGGG and CCNDDNNGGG) motifs were quantified in each L. major, mouse or human chromosome. They are represented as the ratio of observed/expected sequences rO/E, as indicated in Table 1. For each chromosome, the ratio is represented by a single symbol. Significant differences between L. major and vertebrate chromosomes are indicated (***, p<0.001). 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-g006: Selection for inhibitory and against stimulatory TLR9 motifs in vertebrate genome.(A) Poly G8 (GGGG)2, stimulatory GACGTT and inhibitory TTAGGG motifs were quantified in L. major and mouse genomes. Stimulatory GTCGTT motif was quantified in L. major and human genomes. The datas are represented as copy number per 106 bases pair ( = copy number/genome size (bp)*106). (B) Stimulatory (RRCGYY and HRWCGTTN) and inhibitory (WKKVGGGG and CCNDDNNGGG) motifs were quantified in each L. major, mouse or human chromosome. They are represented as the ratio of observed/expected sequences rO/E, as indicated in Table 1. For each chromosome, the ratio is represented by a single symbol. Significant differences between L. major and vertebrate chromosomes are indicated (***, p<0.001). 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 analyzed the genomic frequency of motifs affecting the activation or inhibition of TLR9 in L. major and vertebrate (mouse and human) DNA. 3′extension with polyG reduces nuclease sensitivity [37]. In agreement with the greater resistance of L. major DNA to DNase, we found that the relative frequency of polyG8 motif (represented here as (GGGG)2) was 4 times larger in the genome of L. major than in the mouse genome (Figure 6A and Table S1).


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)

Selection for inhibitory and against stimulatory TLR9 motifs in vertebrate genome.(A) Poly G8 (GGGG)2, stimulatory GACGTT and inhibitory TTAGGG motifs were quantified in L. major and mouse genomes. Stimulatory GTCGTT motif was quantified in L. major and human genomes. The datas are represented as copy number per 106 bases pair ( = copy number/genome size (bp)*106). (B) Stimulatory (RRCGYY and HRWCGTTN) and inhibitory (WKKVGGGG and CCNDDNNGGG) motifs were quantified in each L. major, mouse or human chromosome. They are represented as the ratio of observed/expected sequences rO/E, as indicated in Table 1. For each chromosome, the ratio is represented by a single symbol. Significant differences between L. major and vertebrate chromosomes are indicated (***, p<0.001). 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-g006: Selection for inhibitory and against stimulatory TLR9 motifs in vertebrate genome.(A) Poly G8 (GGGG)2, stimulatory GACGTT and inhibitory TTAGGG motifs were quantified in L. major and mouse genomes. Stimulatory GTCGTT motif was quantified in L. major and human genomes. The datas are represented as copy number per 106 bases pair ( = copy number/genome size (bp)*106). (B) Stimulatory (RRCGYY and HRWCGTTN) and inhibitory (WKKVGGGG and CCNDDNNGGG) motifs were quantified in each L. major, mouse or human chromosome. They are represented as the ratio of observed/expected sequences rO/E, as indicated in Table 1. For each chromosome, the ratio is represented by a single symbol. Significant differences between L. major and vertebrate chromosomes are indicated (***, p<0.001). 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 analyzed the genomic frequency of motifs affecting the activation or inhibition of TLR9 in L. major and vertebrate (mouse and human) DNA. 3′extension with polyG reduces nuclease sensitivity [37]. In agreement with the greater resistance of L. major DNA to DNase, we found that the relative frequency of polyG8 motif (represented here as (GGGG)2) was 4 times larger in the genome of L. major than in the mouse genome (Figure 6A and Table S1).

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