AUTHOR=Sanz-Navarro Maria , Delgado Irene , Torres Miguel , Mustonen Tuija , Michon Frederic , Rice David P. 

TITLE=Dental Epithelial Stem Cells Express the Developmental Regulator Meis1

JOURNAL=Frontiers in Physiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2019.00249

DOI=10.3389/fphys.2019.00249

ISSN=1664-042X

ABSTRACT=<p>MEIS1 is a key developmental regulator of several organs and participates in stem cell maintenance in different niches. However, despite the murine continuously growing incisor being a well described model for the study of adult stem cells, <italic>Meis1</italic> has not been investigated in a dental context. Here, we uncover that <italic>Meis1</italic> expression in the tooth is confined to the epithelial compartment. Its expression arises during morphogenesis and becomes restricted to the mouse incisor epithelial stem cell niche, the labial cervical loop. <italic>Meis1</italic> is specifically expressed by <italic>Sox2<sup>+</sup></italic> stem cells, which give rise to all dental epithelial cell lineages. Also, we have found that <italic>Meis1</italic> in the incisor is coexpressed with potential binding partner <italic>Pbx1</italic> during both embryonic and adult stages. Interestingly, <italic>Meis2</italic> is present in different areas of the forming tooth and it is not expressed by dental epithelial stem cells, suggesting different roles for these two largely homologous genes. Additionally, we have established the expression patterns of <italic>Meis1</italic> and <italic>Meis2</italic> during tongue, hair, salivary gland and palate formation. Finally, analysis of <italic>Meis1</italic>-null allele mice indicated that, similarly, to SOX2, MEIS1 is not essential for tooth initiation, but might have a role during adult incisor renewal.</p>