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Thesis: Pauline MARANGONI

When Dec 05, 2014
from 02:00 to 05:00
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On December 5th in Salle des Theses Chantal Rabourdin-Combe (ENS, Monod campus) Pauline MARANGONI from the team of Laurent VIRIOT (Evo-Devo of vertebrate dentition) will defend her thesis (in english language) entitled:





The evolution of the vertebrate dentition is among the most exciting topics in the evo-devo field, with particular attention being drawn to the mouse model. The mouse dentition includes four ever-growing incisors and twelve molars with a specific cusp pattern. Incisors and molars develop according to a tightly regulated molecular network.

The ERK-MAPK cascade is involved at various stages of tooth development. Molar tooth phenotype comparisons in mutant mice for genes acting at various levels of the cascade highlighted a dental phenotype signature, which consists in the presence of a supernumerary tooth and shared cusp pattern defects. Some of these recall characters present in fossil rodents, supporting the ERK-MAPK as a good candidate to explain some evolutionary trends of the rodent dentition. By working on a mouse line over-expressing one of this pathway inhibitor in the oral epithelium, I perfect our understanding of Fgf gene role in specifying signaling center formation at the right stage, and in achieving correct mineralization.

When considering evergrowing incisors, mouse dentition is also dynamic at the lifetime scale. I monitored the ageing process of the mouse upper incisors, and provided a chronology of occurrence of the variety of age-related defects display. These defects are set up from the six months on, the most frequent abnormality being the presence of an enamel groove along the surface of the incisor. Using Next Generation Sequencing technologies, I detected transcriptomic changes in the stem cell niches affecting cell proliferation and metabolism, as well as the stem cell niche functioning. The correlation found between the groove occurrence and a large immune response in dental tissues expands our concern for dental stem cell ageing.

Key words:

Rodent dentition, ERK-MAPK pathway, comparative dental anatomy, incisor stem cell niches, ageing, gene expression profile