Role of Notch Signaling in the Physiological Patterning of Posterofrontal and Sagittal Cranial Sutures

FGF signaling in cranial suture development and related diseases

Suture mesenchymal stem cells (SMSCs) are a heterogeneous stem cell population with the ability to self-renew and differentiate into multiple cell lineages. The cranial suture provides a niche for SMSCs to maintain suture patency, allowing for cranial bone repair and regeneration. In addition, the cranial suture functions as an intramembranous bone growth site during craniofacial bone development. Defects in suture development have been implicated in various congenital diseases, such as sutural agenesis and craniosynostosis. However, it remains largely unknown how intricate signaling pathways orchestrate suture and SMSC function in craniofacial bone development, homeostasis, repair and diseases. Studies in patients with syndromic craniosynostosis identified fibroblast growth factor (FGF) signaling as an important signaling pathway that regulates cranial vault development. A series of in vitro and in vivo studies have since revealed the critical roles of FGF signaling in SMSCs, cranial suture and cranial skeleton development, and the pathogenesis of related diseases. Here, we summarize the characteristics of cranial sutures and SMSCs, and the important functions of the FGF signaling pathway in SMSC and cranial suture development as well as diseases caused by suture dysfunction. We also discuss emerging current and future studies of signaling regulation in SMSCs.

Targeted sequencing of NOTCH signaling pathway genes and association analysis of variants correlated with mandibular prognathism

Introduction

The purpose of this study was to systematically identify variants in NOTCH signaling pathway genes that correlate with mandibular prognathism (MP) in the general Chinese population.

Methods

Targeted sequencing of NOTCH signaling pathway genes was conducted in 199 MP individuals and 197 class I malocclusion control individuals. The associations of common and rare variants with MP, cephalometric parameters, and continuous cephalometric phenotypes were analyzed by principal component (PC) analysis. The associations between rare variants and MP were tested for each gene.

Results

Six SNPs, including rs415929, rs520688, and rs423023 in an exonic region of NOTCH4; rs1044006 in an exonic region of NOTCH3; rs1051415 in an exonic region of JAG1; and rs75236173 in the 3′-untranslated region (3′-UTR) of NUMB were associated with MP (P < 0.05). One common variant, rs1051415, in an exonic region of JAG1 was significantly related to PC1 (P  = 3.608 × 10^− 4), which explained 24.3% of the overall phenotypic variation observed and corresponded to the sagittal mandibular position towards the maxilla, ranging from a posterior positioned mandible to an anterior positioned mandible. Additionally, 41 other variants were associated with PC1–5 (P  <  0.05). With respect to rare variant analysis, variants within the EP300, NCOR2, and PSEN2 gene showed an association with MP (t   < 0 .05).

Conclusions

An association between NOTCH signaling pathway genes and MP has been identified.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13005-021-00268-0.

Contextual Regulation of Skeletal Physiology by Notch Signaling

PURPOSE OF REVIEW

This article reviews the past 2 years of research on Notch signaling as it relates to bone physiology, with the goal of reconciling seemingly discrepant findings and identifying fruitful areas of potential future research.

RECENT FINDINGS

Conditional animal models and high-throughput omics have contributed to a greater understanding of the context-dependent role of Notch signaling in bone. However, significant gaps remain in our understanding of how spatiotemporal context and epigenetic state dictate downstream Notch phenotypes. Biphasic activation of Notch signaling orchestrates progression of mesenchymal progenitor cells through the osteoblast lineage, but there is a limited understanding of ligand- and receptor-specific functions. Paracrine Notch signaling through non-osteoblastic cell types contributes additional layers of complexity, and we anticipate impactful future work related to the integration of these cell types and signaling mechanisms.