@article {6117, title = {Histone Methylation Participates in Gene Expression Control during the Early Development of the Pacific Oyster .}, journal = {Genes (Basel)}, volume = {10}, year = {2019}, month = {2019 09 10}, abstract = {

Histone methylation patterns are important epigenetic regulators of mammalian development, notably through stem cell identity maintenance by chromatin remodeling and transcriptional control of pluripotency genes. But, the implications of histone marks are poorly understood in distant groups outside vertebrates and ecdysozoan models. However, the development of the Pacific oyster is under the strong epigenetic influence of DNA methylation, and histone-demethylase orthologues are highly expressed during . early life. This suggests a physiological relevance of histone methylation regulation in oyster development, raising the question of functional conservation of this epigenetic pathway in lophotrochozoan. Quantification of histone methylation using fluorescent ELISAs during oyster early life indicated significant variations in monomethyl histone H3 lysine 4 (H3K4me), an overall decrease in H3K9 mono- and tri-methylations, and in H3K36 methylations, respectively, whereas no significant modification could be detected in H3K27 methylation. Early in vivo treatment with the JmjC-specific inhibitor Methylstat induced hypermethylation of all the examined histone H3 lysines and developmental alterations as revealed by scanning electronic microscopy. Using microarrays, we identified 376 genes that were differentially expressed under methylstat treatment, which expression patterns could discriminate between samples as indicated by principal component analysis. Furthermore, Gene Ontology revealed that these genes were related to processes potentially important for embryonic stages such as binding, cell differentiation and development. These results suggest an important physiological significance of histone methylation in the oyster embryonic and larval life, providing, to our knowledge, the first insights into epigenetic regulation by histone methylation in lophotrochozoan development.

}, issn = {2073-4425}, doi = {10.3390/genes10090695}, author = {Alexandre Fellous and Lefranc, Lorane and Jouaux, Aude and Goux, Didier and Pascal Favrel and Riviere, Guillaume} } @article {3394, title = {The Jumonji gene family in Crassostrea gigas suggests evolutionary conservation of Jmj-C histone demethylases orthologues in the oyster gametogenesis and development.}, journal = {Gene}, volume = {538}, year = {2014}, month = {2014 Mar 15}, pages = {164-75}, abstract = {

Jumonji (Jmj) proteins are histone demethylases, which control the identity of stem cells. Jmj genes were characterized from plants to mammals where they have been implicated in the epigenetic regulation of development. Despite the Pacific oyster Crassostrea gigas representing one of the most important aquaculture resources worldwide, the molecular mechanisms governing the embryogenesis and reproduction of this lophotrochozoan species remain poorly understood. However, annotations in the C. gigas EST library suggested the presence of putative Jumonji genes, raising the question of the conservation of this family of histone demethylases in the oyster. Using Primer walking, 5{\textquoteright}-RACE PCR and in silico analyses, we characterized nine Jumonji orthologues in the oyster, called Cg-Jmj, bearing conserved domains critical for putative histone demethylase activity. Phylogenic analyses revealed that oyster Jumonji cluster into two distinct groups: {\textquoteright}single-domain Jmj{\textquoteright} and {\textquoteright}multi-domain Jmj{\textquoteright}, and define 8 subgroups corresponding to each cognate orthologues in metazoans. RT-qPCR investigations showed specific regulations of Cg-Jmj mRNAs during the early development and along the reproduction cycle. Furthermore, in situ and in toto hybridizations indicate that oyster Jumonji genes are transcribed mostly within the gonad in adult oysters whereas they display a ubiquitous expression during embryonic and larval development. Our study demonstrates the presence of nine Jumonji orthologues in the oyster C. gigas. Their domain conservation and their expression profile suggest an implication during reproduction and development, questioning about the epigenetic regulation by histone methylation in lophotrochozoans.

}, keywords = {Animals, Base Sequence, Conserved Sequence, Crassostrea, Evolution, Molecular, Gametogenesis, Gene Expression Regulation, Developmental, Jumonji Domain-Containing Histone Demethylases, Molecular Sequence Data, Multigene Family, RNA, Messenger}, issn = {1879-0038}, doi = {10.1016/j.gene.2013.12.016}, author = {Alexandre Fellous and Pascal Favrel and Guo, Ximing and Guillaume Rivi{\`e}re} } @article {3396, title = {Temperature influences histone methylation and mRNA expression of the Jmj-C histone-demethylase orthologues during the early development of the oyster Crassostrea gigas.}, journal = {Mar Genomics}, year = {2014}, month = {2014 Sep 16}, abstract = {

In many groups, epigenetic mechanisms influence developmental gene regulation under environmental inputs. The Pacific oyster Crassostrea gigas belongs to lophotrochozoans and its larval development is highly dependent on temperature, but the role of epigenetic mechanisms in this context is unknown despite high levels of the recently characterized Jumonji histone demethylase (JHDM) orthologues (Cg_Jumonji) suggesting a physiological relevance of histone methylation in the oyster development. Because in other species alterations of the histone methylation pattern have deleterious outcomes, we investigated the influence of temperature during the oyster larval life on histone methylation and JHDM expression. To shed light on this point, oyster embryonic and early larval development experiments were carried out at different temperatures (18{\textdegree}C, 25{\textdegree}C and 32{\textdegree}C). Histone methylation levels were investigated using fluorescent ELISA at 6 and 24h post-fertilization. When compared to the 25{\textdegree}C group, at 18{\textdegree}C H3K4, H3K9 and H3K27 residues were hypomethylated at 6h post fertilization (hpf) and hypermethylated at 24hpf. In contrast, at 32{\textdegree}C, 6hpf animals present a dramatic hypermethylation (ca. 4-fold) of all examined residues, which is minored but sustained at 24hpf. RT-qPCR investigations of the mRNA expression of the nine oyster JHDMs, showed gene- and stage-specific temperature sensitivities throughout the early life of oysters. This study provides evidence of the biological significance of histone methylation during development in a lophotrochozoan species. Our results also indicate that temperature influences histone methylation, possibly through the expression level of putative actors of its regulation, which might participate in developmental control. To our knowledge, this is the first report indicating a direct relationship between an epigenetic mark and an environmental parameter in marine molluscs. Such investigations could help better understand the molecular mechanisms of development and adaptation in lophotrochozoans.

}, issn = {1876-7478}, doi = {10.1016/j.margen.2014.09.002}, author = {Alexandre Fellous and Pascal Favrel and Guillaume Rivi{\`e}re} }