Developmental Roles of FUSE Binding Protein 1 (Fubp1) in Tooth Morphogenesis.

Yam Prasad Aryal,Sanjiv Neupane,Sanggyu Lee,Ji-Youn Kim,Hitoshi Yamamoto,Chang-Yeol Yeon,Chang-Hyeon An,Eui-Seon Lee,Nitin Kumar Pokhrel,Youngkyun Lee,Shengli An ,Tae‐Young Kim ,Jae‐Kwang Jung ,Tae‐Yub Kwon ,Jung‐Hong Ha ,Do‐Yeon Kim ,Wern‐Joo Sohn ,Eui Kyun Park ,Sung Won Cho ,Jae‐Young Kim

doi:10.3390/ijms21218079

Abstract

FUSE binding protein 1 (Fubp1), a regulator of the c-Myc transcription factor and a DNA/RNA-binding protein, plays important roles in the regulation of gene transcription and cellular physiology. In this study, to reveal the precise developmental function of Fubp1, we examined the detailed expression pattern and developmental function of Fubp1 during tooth morphogenesis by RT-qPCR, in situ hybridization, and knock-down study using in vitro organ cultivation methods. In embryogenesis, Fubp1 is obviously expressed in the enamel organ and condensed mesenchyme, known to be important for proper tooth formation. Knocking down Fubp1 at E14 for two days, showed the altered expression patterns of tooth development related signalling molecules, including Bmps and Fgf4. In addition, transient knock-down of Fubp1 at E14 revealed changes in the localization patterns of c-Myc and cell proliferation in epithelium and mesenchyme, related with altered tooth morphogenesis. These results also showed the decreased amelogenin and dentin sialophosphoprotein expressions and disrupted enamel rod and interrod formation in one- and three-week renal transplanted teeth respectively. Thus, our results suggested that Fubp1 plays a modulating role during dentinogenesis and amelogenesis by regulating the expression pattern of signalling molecules to achieve the proper structural formation of hard tissue matrices and crown morphogenesis in mice molar development.

Highlights

Organogenesis is a complex phenomenon by which cells of different embryonic origin develop and associate to form organs [1]
The localization of E-cadherin in epithelial cells revealed that cellular adhesion seemed weaker in the inner enamel epithelial cells of the knock-down specimen compared with the control (Figure 3a,d)
Tooth development is regulated with the complex interactions of various signalling molecules [6,21], and most of the tooth development-related signalling molecules were examined using Quantitative PCR (qPCR) to evaluate the knock-down effects of FUSE binding protein 1 (Fubp1)

Summary

Introduction

Organogenesis is a complex phenomenon by which cells of different embryonic origin develop and associate to form organs [1]. Through the combined interactions of signalling molecules and transcription factors, tooth development proceeds with bud, cap, and bell stages at mouse embryonic stages E13, 14, and 16, respectively, which shows typical morphologic features of epithelial appendages with epithelial invaginations at E13, signalling centre formation with specific epithelial structural formation of enamel knot at E14, and functional differentiation of odontoblasts and ameloblasts at E16 [6,7]. The spatio-temporal regulation of genes at cap and bell stages play crucial roles for functional and structural formation of tooth [6]. The functional evaluation of Fubp, a transcriptional regulator gene, is performed at cap stage through siRNA knock-down and in vitro organ cultivation system to evaluate the developmental role of Fubp prior to differentiation of odontoblasts and ameloblasts. Since the functional evaluation of transcriptional regulators, even though their importance in development, was difficult to perform in knockout animal models [3,6,9,19], this in vitro organ cultivation approach would be the plausible model system to provide the fine-tuning of transcription regulations by Fubp

Expression Pattern and Functional Evaluation of Fubp1

Altered Expression Patterns of Signalling Molecules by Fubp1 Knock-Down

Fubp1 in Tooth Morphogenesis

Animals

In Situ Hybridization