Researchers use mouse model to study craniofacial disorders

February 25, 2016

KANSAS CITY, MO -- Researchers from the laboratory of Paul Trainor, Ph.D., at the Stowers Institute of Medical Research have developed an effective and reliable technique for studying high-arched palate using a mouse model. The methodology could expand research into the genetic aspects of this craniofacial abnormality.

Craniofacial anomalies like high-arched and cleft palate account for one third of all human congenital birth disorders. While there are a number of animal models for studying cleft palate that have provided insight on the biology of that condition, there are very few models for studying high-arched palate.

High-arched palate, also known as "pseudo-cleft" or "vaulted palate," refers to a pronounced curvature of the roof of the mouth. It can lead to enlarged gums, crowded molars and other dental problems, impair speech, and negatively affect a person's quality of life. But its genetic roots remain unclear, in part because researchers have lacked animal models in which to study the condition.

"High-arched palate is under-researched at the basic science level, given its presence in a relatively large number of syndromes," says Zachary Conley, the paper's first author. "A greater understanding of high-arched palate can lead to insights into palatogenesis, or the generation of the palate, as a complex developmental process. Our quantitative methodology sets the stage for further study of this condition."

Mice have long been used in genetic disorder research to mimic human diseases. For this study, Trainor Lab researchers and their collaborators used a mouse model of Treacher Collins syndrome (TCS), a human congenital condition that affects about 1 in 50,000 live births and impairs the bone and tissue development of the head and face, including the palate.

The researchers generated 3-D images of the palates of the mice at several stages of development using nuclear fluorescence imaging, which uses luminous dyes to observe objects that light-based microscopy cannot. Key characteristics -- palate shelf length, shelf width, arch height, and arch angle -- were statistically analyzed to establish significant, consistent criteria that define high-arched palates. In keeping with standard practices of clinical metrics, the researchers classified as abnormal features measuring more than two standard deviations from those found in the control group mice.

The TCS mice showed signs of palate formation problems during development, and about 46 percent exhibited a soft or fully cleft palate. TCS mice also showed significantly higher arched palate compared to their control counterparts, as defined by shelf height and angle differences -- a clear validation of the research team's criteria.

Published online ahead of print in the journal Developmental Biology, the study was enabled by a 10-year research effort by the Trainor Lab and collaborators to understand the causes and effects of TCS. "Our work over the last decade has been aimed at understanding how Treacher Collins syndrome occurs, what cells and tissues are affected, and what we might be able to do to prevent it," says Trainor.

One promising finding of the study showed that TCS mice born to mothers with reduced p53 gene function showed no signs of cleft palate.

In prior work, the Trainor Lab linked the p53 gene to an uptick in neuroepithelial cell death and a resulting decline in migrating neural crest cells, which produce most of the cartilage, bone and connective tissue in an embryo's face and head. Without a sufficient supply of these cells, key areas of the developing mouth and nasal cavity fail to grow together and fully form.

In the current study, by generating TCS mice with impaired p53 gene function, the researchers were able to improve, or rescue, the high-arched palate phenotype, suggesting a link between tissue formed by cranial neural crest cells and the underdevelopment of the palatal shelf in the pathogenesis of high-arched palate.

In related research, the Trainor Lab and collaborators have recently shown that the neuroepithelial cells that give rise to neural crest cells show a marked sensitivity to oxidative stress, and that maternal antioxidant supplementation can lessen or prevent craniofacial abnormalities in the TCS mouse model. These findings suggest that maternal antioxidant supplementation, which suppresses oxidative stress-induced p53-dependent neuroepithelial cell death, may be a possible avenue for clinical prevention of TCS. The study was published in the Jan. 21, 2016 issue of Nature Communications.

"We've used a pharmacological approach of prenatal antioxidant supplementation to reduce craniofacial anomalies in TCS mice," says Daisuke Sakai, PhD, first author of the paper and former postdoc in the Trainor Lab currently at Doshisha University, Japan. "Our findings provide new insights into potential therapeutic avenues for prevention of Treacher Collins syndrome."

"Our recent papers highlight the fundamental importance of basic biology in understanding clinical problems, by defining the origins of birth defects and their possible prevention" Trainor says.
Other authors on the Developmental Biology paper included Molly Hague and Hiroshi Kurosaka, Ph.D., from the Stowers Institute; Jill Dixon, Ph.D., from the Manchester Academic Health Sciences Center, UK; and Michael Dixon, Ph.D., from the University of Manchester, UK. Other authors on the Nature Communications paper included Annita Achilleos, Ph.D., from the Stowers Institute; J. Dixon; and M. Dixon.

The studies were funded by the Stowers Institute, the Healing Foundation, and the National Institute of Dental and Craniofacial Research of the National Institutes of Health (R01DE016082). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.

Lay Summary of Findings

Researchers at the Stowers Institute for Medical Research have found a way to use mice to study high-arched palate, a disorder in which the roof of the mouth is oddly high and steep. The mice mimic Treacher Collins syndrome (TCS) in humans, of which high-arched palate is a feature. To help this research move forward, scientists needed to come up with a consistent, measurement-based definition of high-arched palate, one they could use across all mouse models.

With this in mind, researchers from the laboratory of Paul Trainor, Ph.D., and their collaborators used a 3-D imaging technique to measure the palates of the offspring to see which of their attributes -- palate shelf length, shelf width, arch height, or arch angle -- were significantly different. They found that TCS mice had much higher palate arches, in terms of shelf height and angle, than the normal mice.

The researchers were interested to find that TCS mice born to mothers with impaired p53 gene function did not develop cleft palates. This finding, which follows an earlier study that showed a link between p53 and the death of key cells that form an embryo's face and head, warrants further exploration.

Recent related work from the Trainor Lab and their collaborators showed that TCS mice born to mothers that had received antioxidant supplements exhibited fewer craniofacial abnormalities than control group mice. This observation suggests that maternal antioxidant supplementation may provide a way to protect against TCS.

Building on a decade of work by the Trainor Lab and their collaborators to understand the causes and effects Treacher Collins syndrome, these findings demonstrate the importance of fundamental biological research for understanding the origins of health problems and possible approaches to their prevention.

About the Stowers Institute for Medical Research

The Stowers Institute for Medical Research is a non-profit, basic biomedical research organization dedicated to basic research - the critical first step in the quest for new medical diagnostics, therapies and treatments. Jim Stowers, founder of American Century Investments, and his wife, Virginia, opened the Institute in 2000. Since then, the Institute has spent over one billion dollars in pursuit of its mission.

Currently, the Stowers Institute is home to 500 researchers and support personnel, over 20 independent research programs, and more than a dozen technology development and core facilities.

Stowers Institute for Medical Research

Related Cleft Palate Articles from Brightsurf:

For children with cleft lip and palate, no major psychological impact of repeated surgeries
Children born with cleft lip and cleft palate (CLP) commonly undergo multiple surgical procedures between infancy and adolescence.

Children born with a cleft lip unlikely to be genetically inclined to do poorly at school
New research has found that children born with a cleft lip, either with or without a cleft palate, are not likely to be genetically predisposed to do less well at school than their peers.

Skin and non-adhesive cells found to play pivotal role in the formation of fin
Human fingers are sculpted from a primitive pad-like structure during embryonic development.

Speech impairment in five-year-old international adoptees with cleft palate
In a group of internationally adopted children with cleft lip and/or palate, speech at age five is impaired compared to a corresponding group of children born in Sweden, a study shows.

Variation in the shape of speech organs influences language evolution
Why do speech sounds vary across languages? Does the shape of our speech organs play a role?

The mystery behind cleft palate and lips: Study shines a light on genetic factors
Researchers found more than 100 new genes that could lead to the development of cleft lip and palates.

Salamanders chew with their palate
'According to the textbooks, amphibians swallow their prey whole, but we have been able to refute this,' says Dr.

New technique uses umbilical cord stem cells for early repair of cleft palate
A technique using umbilical cord blood stem cells could be a promising new approach for repair of cleft palate in infants, reports a paper in The Journal of Craniofacial Surgery, published in the Lippincott portfolio by Wolters Kluwer.

Novel genome-wide association study risk loci for nonsyndromic orofacial clefts
At the 96th General Session of the International Association for Dental Research (IADR), held in conjunction with the IADR Pan European Regional (PER) Congress, Azeez Butali, University of Iowa, Iowa City, USA, gave an oral presentation titled 'Novel Genome-wide Association Study Risk Loci for Nonsyndromic Orofacial Clefts.'

In the gaping mouth of ancient crocodiles
A new study by a team of international experts, led by University of Witwatersrand PhD candidate Kathleen Dollman and Professor Jonah Choiniere published today in the American Museum Novitates, endeavoured to further explore the mouth of one of the earliest occurring and least understood groups of crocodilians, the shartegosuchids.

Read More: Cleft Palate News and Cleft Palate Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to