Characterization of Autosomal Recessive Radicular Dentin Dysplasia EOE Cells

Radicular Dentin Dysplasia (RDD) is a rare inherited disorder characterized by incomplete or absent root formation resulting in premature tooth exfoliation. We have previously identified a nuclear factor I-C (NFI-C) mutation associated with an autosomal recessive (AR) form of RDD. NFI-C, a member of NFI gene family, functions as a transcription factor and has been shown to be critical for root formation. Objectives: 1)To establish primary cell cultures from enamel organ epithelial (EOE) cells from a AR-RDD patient; 2) describe their growth rate and NFI-C alterative splicing patterns; 3)characterize the gene expression profile of NFI-C related to its biolgoical function; and 4)identify critical EOE downstream target genes. Methods: Residual EOE cells from an unerupted mandibular molar of an AR-RDD patient were dissected, cultured and grown in parallel with control EOE cells. These EOE cells were expanded and used for immunolocalization, cell viability, apoptosis assays, quanitative real-time PCR analysis (qRT-PCR) and gene array comparisons using Affymetrix human genome U133- Plus-2.0 chips. NFI-C nuclear localization and cellular matrix mineralization was determined by immunohistochemistry and in situ alkaline phosphatase (ALP) staining. Results: The AD-RDD EOE cells represent a heterogenous population as determined by morphology and ALP staining. No alterations in NFI-C nuclear translocation or NFI-C isoform expression profiles were found with similar patterns of ALP expression. However, the NFI-C mutation in the EOE cells was found to alter cell proliferation and apoptotic pathways. Microarray data showed alterations in differentially expressed gene levels due to the NFI-C mutation, which were confirmed by qRT-PCR. Conclusions: We have established epithelial-derived dental cells from a AR-RDD patient for the first time. Our studies indicate that the NFI-C mutation associated with AR-RDD interferes with normal signaling cascades critical for root formation allowing novel downstream genes to be identified. Support: UAB-IOHR/NIDCR-F30DE0180803/ProDoc-CAPES(ACA; Brazil).