Stem Cells, Development and Evolution
Stem cells, which are able to both self-renew and produce a differentiated progeny, are crucial players of animal embryonic development. They are also involved in post-embryonic processes such as growth, tissue homeostasis, as well as, in some animals, asexual reproduction and regeneration. Regeneration, the ability to restore lost parts of the body, is a widespread phenomenon in animals. Whilst this ability is very limited in mammalians, many animals (such as sponges, cnidarians, planarians, annelids, and salamanders) are able to regenerate complex structures, limbs for example, and in some cases their whole body from a small piece of tissue. Regeneration is often based on the presence of populations of stem cells, either pluripotent and able to regenerate all the different tissues, or multipotent and with a much more restricted potential. Regeneration can also rely on local cell dedifferentiation processes by which differentiated cells are reprogramed into proliferating progenitor or stem cells.
Our team is interested in understanding the evolution of stem cells and regeneration in animals. Our main model to address these topics is the marine annelid Platynereis dumerilii (Figure 1).
Annelid worms belong to lophotrochozoans, the third large evolutionary lineage of the bilaterians, alongside deuterostomes (vertebrates, echinoderms, ...) and ecdysozoans (arthropods, nematodes, ...). Platynereis is a slow-evolving species that has been shown to be extremely valuable for large-scale evolutionary comparisons and that is amenable to molecular and functional analyses. After embryonic and larval development, Platynereis worms grow during most of their life, by sequentially adding new segments at their posterior end: a process known as posterior elongation. We showed that this property is linked to the presence of two populations of putative stem cells located in a subterminal ‘growth zone’ (GZ; Figure 2). We also showed that these stem cells display a molecular signature (made of the expression of about 20 genes) similar to that of pluripotent stem cells found in other animals and that of primordial germ cells. Platynereis worms also able to regenerate the posteriormost part of their body, including the GZ, upon amputation.
One of our main current projects is to characterize, with a large variety of molecular, cellular and genomic tools, the different steps of the posterior regeneration process in Platynereis and to define the respective roles of pre-existing stem cells and dedifferentiation in the process. A general aim is also to determine, through comparative analyses, whether regeneration in bilaterians relies on conserved mechanisms and genetic programs. We also try to define a more extensive molecular signature for the Platynereis posterior stem cells and determine to which extant this signature is conserved in stem cells and primordial germ cells of other animals.
The team is part of the Labex “Who am I?”
Stem cells, regeneration, annelids, evolution, development, pluripotency, Platynereis, multipotency, germ cells, comparative genomics, lophotrochozoans, phylogeny
Selection of publications
Vervoort M., Meulemeester D., Béhague J., Kerner P. (2016). Evolution of Prdm genes in animals: insights from comparative genomics. Molecular Biology and Evolution 33: 679-696.
Gazave E., Behague J., Laplane L., Guillou A., Demilly A., Balavoine G., Vervoort M. (2013). Posterior elongation in the annelid Platynereis dumerilii involves stem cells molecularly related to primordial germ cells. Developmental Biology 382: 246-267.
Demilly A., Steinmetz P., Gazave E., Marchand L., Vervoort M. (2013). Involvement of the Wnt/β-catenin pathway in neurectoderm architecture in Platynereis dumerilii. Nature Communications4: 1915.
Kerner P., Degnan S.M., Marchand L., Degnan B.M., Vervoort M. (2011). Evolution of RNA-binding proteins in animals: insights from genome-wide analysis in the sponge Amphimedon queenslandica. Molecular Biology and Evolution 28: 2289-2303.
Demilly A., Simionato E., Ohayon D., Kerner P., Garcès A., Vervoort M. (2011). Coe genes are expressed in differentiating neurons in the central nervous system of protostomes. PLoS One 6: e21213.