| Abstrakt: |
Human third molars are the last developing teeth and are often extracted. As such they can serve as an easily accessible model for human tooth development. Cells responsible for tooth development originate from the cranial neural crest. We have characterized different compartments of impacted third molars by specific signatures of gene expression. From two of the compartments, the pulp proper and the pad-like tissue (PLT), we derived cell cultures. In order to see how the influence of the tissue diversification is translated and carried on in cell culture we analyzed their gene expression profile by microarray analysis. Signatures were found to be significantly different between both groups and varied between 2218 and 6928 in total numbers on the basis of P = 0.01. Since cRNAs gained from cells derived from pulp and PLT were labeledprior to hybridization with Cy5 and Cy3, respectively, we were able to assign all red and green signals to pulp or PLT representative signatures. In all, representative signals for cells derived from pulp ranged from 749 to 3405 (red) and from 1002 to 3523 for PLT signatures (green) depending on the samples analyzed. Focusing on intersections within all derivatives from pulp or PLT, only few genes were significantly matched in color. For all cell cultures derived from pulp, 11 signatures overlapped. Among these, annotated genes were WNT16 (wingless-type mouse mammary tumor virus [MMTV] integration site family, member 16), interferon (α, β and ω) receptor 2 (IFNAR2), microphthalmia-associated transcription factor (MITF) and methyl transferase like 7A (METTL7A). Representative for all cell cultures derived from PLT were eight signatures with annotated genes, such as semaphoring VIA (SEMA6A), myogenic factor 5 (MYF5), tyrosine aminotransferase (TAT) and IQCA-protein (IQCA). A 2D clustering of the array-data resulted in the formation of two main clusters according to signatures that showed, at least in three of four cases, a significant 'pulp or PLT character', in other words, were significantly red or green ('cluster view'). The same genes as listed above for intersection formation could be found as PLT or pulp representatives via cluster analysis. Therefore we propose that already in the early stage of tooth development neural crest-derived progenitor cells obtained from PLT and developing pulp show substantial differences in their respective gene expression profiles on a whole genome scale. This indicates a compartment-dependent commitment of the isolated cells. [ABSTRACT FROM AUTHOR] |
