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Henriquez , Joaquin

University of British Columbia

The aim of my research is to discover the cellular and molecular events that allow continuous tooth replacement in adult leopard geckos (Eublepharis macularius). Tooth replacement requires multipotent stem cells. It has been suggested that the dental lamina harbours slow-cycling epithelial stem cells that retain 5′-bromo-2′-deoxyuridine (BrdU). The fate of these BrdU label-retaining cells has not been examined. Here, selective tooth removal was used to induce quiescent cells to enter the cell cycle. The newest tooth buds, not present at the time of tooth removal, had fragmented BrdU cells in the different layers of the enamel organ. We also analyzed a variation of the selective tooth removal experiment where treatment with Ferric Sulfate fully ablated the dental stem cells, blocking tooth development in the affected region. We next studied tooth resorption which is necessary for teeth to be shed. RNA-seq was used to profile transcriptional differences between functional erupted teeth and developing un-erupted teeth. Some of the most highly expressed genes in functional teeth are related to osteoclast function. Cathepsin K (CTSK)-positive cells were located in the pulp and within resorption pits in the dentin of functional teeth. These cells are odontoclasts. We found a second population of smaller, CTSK+ cells in the periphery of developing teeth that may be precursors of odontoclasts. We tested whether developing teeth expressed signals that supported odontoclast recruitment and survival. Tooth removal resulted in a significant reduction in CTSK+ cells. We also targeted osteoclasts molecularly using a colony-stimulating factor 1 receptor (CSF1R) antagonist. Beads soaked in BLZ945 antagonist caused a significant decrease in CSF1R and CTSK in tooth samples showing that CSF1 signaling is upstream of CTSK. To further characterize the heterogeneity of the dental cells after selective tooth removal, we carried out single-cell RNA-seq. We found certain genes were upregulated in plucked samples of putative epithelial cells, that may have been activated specifically in response to tooth removal. Tooth replacement research findings presented in this thesis are not only relevant to dental diseases but also more broadly to the field of tissue and organ regeneration.

Text; Dataset

2024-07-02

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/88548

Cell and Developmental Biology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/