Functional Study of Ectodysplasin-A Mutations Causing Non-Syndromic Tooth Agenesis.

Wenjing Shen,Guozhong Zhang,Yang Liu,Hongshan Zhao,Yue Wang,Dong Han,Malcolm L Snead,Haochen Liu,Hailan Feng,Tao Cai

doi:10.1371/journal.pone.0154884

Wenjing Shen, Guozhong Zhang + Show 8 more

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https://doi.org/10.1371/journal.pone.0154884

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Abstract

Recent studies have demonstrated that ectodysplasin-A (EDA) mutations are associated with non-syndromic tooth agenesis. Indeed, we were the first to report three novel EDA mutations (A259E, R289C and R334H) in sporadic non-syndromic tooth agenesis. We studied the mechanism linking EDA mutations and non-syndromic tooth agenesis in human embryonic kidney 293T cells and mouse ameloblast-derived LS8 cells transfected with mutant isoforms of EDA. The receptor binding capability of the mutant EDA1 protein was impaired in comparison to wild-type EDA1. Although the non-syndromic tooth agenesis-causing EDA1 mutants possessed residual binding capability, the transcriptional activation of the receptor’s downstream target, nuclear factor κB (NF-κB), was compromised. We also analyzed the changes of selected genes in other signaling pathways, such as WNT and BMP, after EDA mutation. We found that non-syndromic tooth agenesis-causing EDA1 mutant proteins upregulate BMP4 (bone morphogenetic protein 4) mRNA expression and downregulate WNT10A and WNT10B (wingless-type MMTV integration site family member 10A and 10B) mRNA expression. Our results indicated that non-syndromic tooth agenesis causing EDA mutations (A259E, R289C and R334H) were loss-of-function, and suggested that EDA may regulate the expression of WNT10A, WNT10B and BMP4 via NF-κB during tooth development. The results from our study may help to understand the molecular mechanism linking specific EDA mutations with non-syndromic tooth agenesis.

Highlights

Tooth agenesis is a term used to describe the failure to develop all normally developing deciduous or permanent teeth, and is one of the most common developmental anomalies in humans [1]
The results showed that the expression of wild-type and mutant EDA1 or EDA2 proteins could be detected in 293T cell lysates (Figs 1A and 2A) and supernatant (Figs 1B and 2B), indicating that all the protein constructs could be expressed and secreted out of the transfected cells
The results showed that the binding of all non-syndromic tooth agenesis-causing EDA1 proteins to the receptor EDAR was variably reduced compared with wild-type, but not abolished (Fig 1C and 1D)

Summary

Introduction

Tooth agenesis is a term used to describe the failure to develop all normally developing deciduous or permanent teeth, and is one of the most common developmental anomalies in humans [1]. It can occur in isolation or in association with other genetic diseases as part of a recognized clinical syndrome, such as hypohidrotic ectodermal dysplasia (HED), which are defined as syndromic tooth agenesis [2]. EDA1 has been shown to bind to EDAR, a member of the TNF receptor superfamily, and activates the NF-κB pathway [21]. EDA2 exclusively binds to XEDAR, another member of the TNF receptor superfamily, and activates the NF-κB pathway [21]

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Conclusion