Poster Presentation 44th Lorne Genome Conference 2023

Iroquois 3 plays an essential role in odontogenesis   (#260)

Anrizandy Narwidina 1 2 , Aya Miyazaki 2 , Iwata Kokoro 3 , Rika Kurogoushi 2 , Tomonori Iwasaki 2 , Tsutomu Iwamoto 3
  1. Pediatric Dentistry and Special Need Care, Universitas Gadjah Mada, Yogyakarta, Indonesia
  2. Pediatric Dentistry and Special Need Care, Tokushima University, Tokushima, Japan
  3. Pediatric Dentistry and Special Need Care, Tokyo Medical and Dental University, Tokyo, Japan

Tooth development is a complicated process with dental epithelium-mesenchymal interaction. Identification and characterization of functional molecules are essential for understanding this complex process. Iroquois homeobox transcription factor (Irx) plays an important role in many developmental processes, including odontogenesis. Irx1 is expressed in the outer dental epithelium. However, it is not clear whether other Irx family members are involved in tooth development. This research aims to investigate the expression and function of the Irxs family in tooth development. Using P1 mouse teeth cDNA, we first investigated the expression of Irx-1, -2, -3, -4, -5, and -6 by RT- PCR. RT- PCR revealed that all Irxs except Irx4 were expressed in teeth tissue. In addition, Irx3 has been expressed in mouse dental papilla-derived (mDP) cells and stem cells from human exfoliated deciduous teeth (SHED). A mDP cell culture method was used to elucidate the further characterization of Irx3. During the differentiation of mDP cells, Irx3 expression changed. Suppression of endogenous Irx3 expression by siRNA inhibited mDP cell proliferation and differentiation. Immunostaining demonstrated IRX3 positive signal detected at the epithelial cells and mesenchymal condensation. Wnt3a, Wnt5a, and BMP4 are substantially expressed in mDP cells by quantitative PCR analysis. We also found that the expression of Wnt5a, but not of Wnt3a and BMP4, was suppressed by Irx3 siRNA. These results suggest that Irx3 plays an important role in the proliferation and differentiation of dental mesenchymal cells and may regulate Wnt5a expression during odontoblast differentiation.

Keywords

Tooth development; Iroquois homeobox family; Iroquois 3 (Irx3); differentiation

Correspondence to: Professor Tsutomu Iwamoto, DDS, Ph.D. Department of Pediatric Dentistry/ Special Needs Dentistry, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. Email: Iwamoto.dohs@tmd.ac.jp