Limits...
Schistosoma mansoni mucin gene (SmPoMuc) expression: epigenetic control to shape adaptation to a new host.

Perrin C, Lepesant JM, Roger E, Duval D, Fneich S, Thuillier V, Alliene JF, Mitta G, Grunau C, Cosseau C - PLoS Pathog. (2013)

Bottom Line: We compared the DNA sequences and chromatin structure of SmPoMuc promoters of two S. mansoni strains that are either compatible (C) or incompatible (IC) with a reference snail host.In contrast, promoters carry epigenetic marks that are significantly different between the C and IC strains.Our results indicate that transcription polymorphism of a gene family that is responsible for an important adaptive trait of the parasite is epigenetically encoded.

View Article: PubMed Central - PubMed

Affiliation: Université de Perpignan Via Domitia, Perpignan, France.

ABSTRACT
The digenetic trematode Schistosoma mansoni is a human parasite that uses the mollusc Biomphalaria glabrata as intermediate host. Specific S. mansoni strains can infect efficiently only certain B. glabrata strains (compatible strain) while others are incompatible. Strain-specific differences in transcription of a conserved family of polymorphic mucins (SmPoMucs) in S. mansoni are the principle determinants for this compatibility. In the present study, we investigated the bases of the control of SmPoMuc expression that evolved to evade B. glabrata diversified antigen recognition molecules. We compared the DNA sequences and chromatin structure of SmPoMuc promoters of two S. mansoni strains that are either compatible (C) or incompatible (IC) with a reference snail host. We reveal that although sequence differences are observed between active promoter regions of SmPoMuc genes, the sequences of the promoters are not diverse and are conserved between IC and C strains, suggesting that genetics alone cannot explain the evolution of compatibility polymorphism. In contrast, promoters carry epigenetic marks that are significantly different between the C and IC strains. Moreover, we show that modifications of the structure of the chromatin of the parasite modify transcription of SmPoMuc in the IC strain compared to the C strain and correlate with the presence of additional combinations of SmPoMuc transcripts only observed in the IC phenotype. Our results indicate that transcription polymorphism of a gene family that is responsible for an important adaptive trait of the parasite is epigenetically encoded. These strain-specific epigenetic marks are heritable, but can change while the underlying genetic information remains stable. This suggests that epigenetic changes may be important for the early steps in the adaptation of pathogens to new hosts, and might be an initial step in adaptive evolution in general.

Show MeSH

Related in: MedlinePlus

Chromatin immunoprecipitation on SmPoMuc promoter regions.Experiments were performed on chromatin isolated from miracidia from both the IC (black bars) and C strains (dashed grey bars) (A.) and on chromatin isolated from IC strain miracidia (Black bars), cercaria (grey bars) and adults (white bars) (B.). ChIP was performed with antibodies against H3 acetylated on lysine 9 and H3 tri-methylated on lysine 9. Immunoprecipitated chromatin was analysed by qPCR using primers that hybridize with specific sequences of SmPoMuc group 3.1(r1–r2), group 1and group 3.1. Results represent the percentage input recovery (%IR) on target genes normalised with %IR of a reference gene (αTub). Results are the average of 3 biological samples. * indicates a p-value<0.05 of a student t test.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3757033&req=5

ppat-1003571-g005: Chromatin immunoprecipitation on SmPoMuc promoter regions.Experiments were performed on chromatin isolated from miracidia from both the IC (black bars) and C strains (dashed grey bars) (A.) and on chromatin isolated from IC strain miracidia (Black bars), cercaria (grey bars) and adults (white bars) (B.). ChIP was performed with antibodies against H3 acetylated on lysine 9 and H3 tri-methylated on lysine 9. Immunoprecipitated chromatin was analysed by qPCR using primers that hybridize with specific sequences of SmPoMuc group 3.1(r1–r2), group 1and group 3.1. Results represent the percentage input recovery (%IR) on target genes normalised with %IR of a reference gene (αTub). Results are the average of 3 biological samples. * indicates a p-value<0.05 of a student t test.

Mentions: Since all our experiments had delivered results in favour of a difference in chromatin structure of the SmPoMuc locus between strains, we decided to investigate the chromatin status in these loci. The occurrence of DNA methylation in S.mansoni is currently debated [28][29]. To test for DNA methylation in the promoter region of SmPoMucs we performed bisulfite genomic sequencing of DNA from miracidia using in-vitro methylated DNA as a positive control. We did not detect any methylated cytosine in the target region while 98% of the CpGs of in-vitro methylated DNA scored methylation positive. Our results are in line with earlier results showing that DNA methylation is rare from genes in S.mansoni[29][28]. We then performed Chromatin ImmunoPrecipitation (ChIP) experiments to check for histone modifications in the promoter regions. Due to the high similarity between the different groups of SmPoMuc promoters, ChIP-qPCR (quantitative Polymerase Chain Reaction) analysis was possible only in degenerate regions. Therefore, the chromatin structure analysis was performed on the promoter regions of SmPoMuc groups 1, 3.1 and 3.1(r1–r2). ChIP experiments were performed using an antibody that recognised Histone 3 acetylated on lysine 9 (H3K9Ac) and Histone 3 tri-methylated on lysine 4 (H3K4Met3) which are euchromatic marks and an antibody that recognised H3 tri-methylated on lysine 9 (H3K9Met3), which is a heterochromatic mark. Immunoprecipitation with the antibody that targets H3K4Met3 did not show any enrichment in the SmPoMuc region tested for either the IC or C strains whereas controls, αTub (Smp_090120.2) and 28S (Z46503.1) were positive (data not shown). The H3K4Met3 mark is usually very sharp and difficult to localise by target approach.. Both SmPoMuc group 1 and 3.1(r1–r2) from the IC strain displayed a higher level of H3K9Ac compared to the C strain (fig. 5). Consistent with this result, the C strain displayed a higher level of the heterochromatic mark (H3K9Met3) for group 1 and 3.1(r1–r2). These results have been obtained with several generations of the parasite, demonstrating that the phenotype is transmitted to the next generation.


Schistosoma mansoni mucin gene (SmPoMuc) expression: epigenetic control to shape adaptation to a new host.

Perrin C, Lepesant JM, Roger E, Duval D, Fneich S, Thuillier V, Alliene JF, Mitta G, Grunau C, Cosseau C - PLoS Pathog. (2013)

Chromatin immunoprecipitation on SmPoMuc promoter regions.Experiments were performed on chromatin isolated from miracidia from both the IC (black bars) and C strains (dashed grey bars) (A.) and on chromatin isolated from IC strain miracidia (Black bars), cercaria (grey bars) and adults (white bars) (B.). ChIP was performed with antibodies against H3 acetylated on lysine 9 and H3 tri-methylated on lysine 9. Immunoprecipitated chromatin was analysed by qPCR using primers that hybridize with specific sequences of SmPoMuc group 3.1(r1–r2), group 1and group 3.1. Results represent the percentage input recovery (%IR) on target genes normalised with %IR of a reference gene (αTub). Results are the average of 3 biological samples. * indicates a p-value<0.05 of a student t test.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3757033&req=5

ppat-1003571-g005: Chromatin immunoprecipitation on SmPoMuc promoter regions.Experiments were performed on chromatin isolated from miracidia from both the IC (black bars) and C strains (dashed grey bars) (A.) and on chromatin isolated from IC strain miracidia (Black bars), cercaria (grey bars) and adults (white bars) (B.). ChIP was performed with antibodies against H3 acetylated on lysine 9 and H3 tri-methylated on lysine 9. Immunoprecipitated chromatin was analysed by qPCR using primers that hybridize with specific sequences of SmPoMuc group 3.1(r1–r2), group 1and group 3.1. Results represent the percentage input recovery (%IR) on target genes normalised with %IR of a reference gene (αTub). Results are the average of 3 biological samples. * indicates a p-value<0.05 of a student t test.
Mentions: Since all our experiments had delivered results in favour of a difference in chromatin structure of the SmPoMuc locus between strains, we decided to investigate the chromatin status in these loci. The occurrence of DNA methylation in S.mansoni is currently debated [28][29]. To test for DNA methylation in the promoter region of SmPoMucs we performed bisulfite genomic sequencing of DNA from miracidia using in-vitro methylated DNA as a positive control. We did not detect any methylated cytosine in the target region while 98% of the CpGs of in-vitro methylated DNA scored methylation positive. Our results are in line with earlier results showing that DNA methylation is rare from genes in S.mansoni[29][28]. We then performed Chromatin ImmunoPrecipitation (ChIP) experiments to check for histone modifications in the promoter regions. Due to the high similarity between the different groups of SmPoMuc promoters, ChIP-qPCR (quantitative Polymerase Chain Reaction) analysis was possible only in degenerate regions. Therefore, the chromatin structure analysis was performed on the promoter regions of SmPoMuc groups 1, 3.1 and 3.1(r1–r2). ChIP experiments were performed using an antibody that recognised Histone 3 acetylated on lysine 9 (H3K9Ac) and Histone 3 tri-methylated on lysine 4 (H3K4Met3) which are euchromatic marks and an antibody that recognised H3 tri-methylated on lysine 9 (H3K9Met3), which is a heterochromatic mark. Immunoprecipitation with the antibody that targets H3K4Met3 did not show any enrichment in the SmPoMuc region tested for either the IC or C strains whereas controls, αTub (Smp_090120.2) and 28S (Z46503.1) were positive (data not shown). The H3K4Met3 mark is usually very sharp and difficult to localise by target approach.. Both SmPoMuc group 1 and 3.1(r1–r2) from the IC strain displayed a higher level of H3K9Ac compared to the C strain (fig. 5). Consistent with this result, the C strain displayed a higher level of the heterochromatic mark (H3K9Met3) for group 1 and 3.1(r1–r2). These results have been obtained with several generations of the parasite, demonstrating that the phenotype is transmitted to the next generation.

Bottom Line: We compared the DNA sequences and chromatin structure of SmPoMuc promoters of two S. mansoni strains that are either compatible (C) or incompatible (IC) with a reference snail host.In contrast, promoters carry epigenetic marks that are significantly different between the C and IC strains.Our results indicate that transcription polymorphism of a gene family that is responsible for an important adaptive trait of the parasite is epigenetically encoded.

View Article: PubMed Central - PubMed

Affiliation: Université de Perpignan Via Domitia, Perpignan, France.

ABSTRACT
The digenetic trematode Schistosoma mansoni is a human parasite that uses the mollusc Biomphalaria glabrata as intermediate host. Specific S. mansoni strains can infect efficiently only certain B. glabrata strains (compatible strain) while others are incompatible. Strain-specific differences in transcription of a conserved family of polymorphic mucins (SmPoMucs) in S. mansoni are the principle determinants for this compatibility. In the present study, we investigated the bases of the control of SmPoMuc expression that evolved to evade B. glabrata diversified antigen recognition molecules. We compared the DNA sequences and chromatin structure of SmPoMuc promoters of two S. mansoni strains that are either compatible (C) or incompatible (IC) with a reference snail host. We reveal that although sequence differences are observed between active promoter regions of SmPoMuc genes, the sequences of the promoters are not diverse and are conserved between IC and C strains, suggesting that genetics alone cannot explain the evolution of compatibility polymorphism. In contrast, promoters carry epigenetic marks that are significantly different between the C and IC strains. Moreover, we show that modifications of the structure of the chromatin of the parasite modify transcription of SmPoMuc in the IC strain compared to the C strain and correlate with the presence of additional combinations of SmPoMuc transcripts only observed in the IC phenotype. Our results indicate that transcription polymorphism of a gene family that is responsible for an important adaptive trait of the parasite is epigenetically encoded. These strain-specific epigenetic marks are heritable, but can change while the underlying genetic information remains stable. This suggests that epigenetic changes may be important for the early steps in the adaptation of pathogens to new hosts, and might be an initial step in adaptive evolution in general.

Show MeSH
Related in: MedlinePlus