Liu, Z; Li, C; Xu, J; Lan, Y; Liu, H; Li, X; Maire, P; Wang, X; Jiang, R. Crucial and Overlapping Roles of Six1 and Six2 in Craniofacial Development. Critical reviews in oral biology and medicine : an official publication of the American Association of Oral Biologists. 2019; 98(5):572-579.
A geneticist team at Cincinnati Children’s Hospital Medical Center previously reported an association of a heterozygous deletion of the SIX2 gene with frontonasal dysplasia in one family, a gene-disease association that has recently been independently validated in another patient family. However, other reports have found no significant craniofacial defects in several patients with heterozygous deletion of the SIX2 gene and no frontonasal defect has been reported in mice heterozygous or homozygous for loss of Six2 function. In this study, Liu et al. demonstrate that Six2 exhibits significantly overlapping patterns of expression with that of Six1 during craniofacial development and these two closely related genes play crucial but partly redundant roles in frontonasal, maxillary, mandibular, and skull development in mice. Results from this study not only validate an important role for Six2 in frontonasal development but also provide new insights into the molecular and cellular mechanisms underlying frontonasal dysplasia
Ehsan, Z; Kurian, C; Weaver, KN; Pan, BS; Huang, G; Hossain, MM; Simakajornboon, N. Longitudinal Sleep Outcomes in Neonates With Pierre Robin Sequence Treated Conservatively. The Journal of Clinical Sleep Medicine. 2019; 15(3):477-482.
This study aimed to describe changes in sleep-related respiratory parameters and sleep architecture in neonates with PRS treated conservatively. These neonates with PRS and OSA, treated conservatively, had an improvement in OAHI with advancing age with the median age of OSA resolution at 15 months. Factors potentially responsible include craniofacial growth and maturational changes of respiratory control.
Metzler, MA; Raja, S; Elliott, KH; Friedl, RM; Tran, NQ H; Brugmann, SA; Larsen, M; Sandell, LL. RDH10-mediated retinol metabolism and RAR-mediated retinoic acid signaling are required for submandibular salivary gland initiation. Development (Cambridge). 2018; 145(15):dev.164822-dev.164822.
Salivary glands are required for eating, digestion, and overall oral health maintenance. Each year, approximately 48,000 people in the U.S. diagnosed with head and neck cancer must undergo radiation treatment that significantly damages/destroys the saliva-producing salivary glands. This leaves patients with the painful and dangerous lifelong condition, xerostomia. In addition to a lack of adequate preventative measures, no cure exists, revealing the importance of developing regenerative therapies. While understanding the signals required for initial development of the salivary glands is a critical step for directing regeneration strategies, these initial development steps are still poorly characterized. This study identifies retinoic acid signaling as a requirement for salivary gland initiation. Using novel ex vivo assays allowing for live-imaging of the developing salivary gland epithelium and mesenchyme, the authors show retinoic acid signaling in the initiating salivary gland transduces exclusively through a single RAR isoform. This study contributes significant knowledge to our understanding of the critical beginning steps of salivary gland development, which can shape salivary gland treatment and regeneration therapies.