Craniofacial abnormalities are the most common form of human birth defects, but their molecular basis remains poorly understood. Highly conserved craniofacial developmental pathways shared across diverse vertebrate species have been shaped by adaptive evolution to produce a tremendous diversity of adaptive craniofacial phenotypes. Fundamental investigation of the genetic basis of these phenotypes will lead to better diagnosis, prevention, and treatment of human birth defects. Indeed, complementary or new information on the genetic basis of many human pathologies in model systems is often obtainable from naturally occurring systems that display analogous divergent phenotypes. These natural systems are now feasible for genomic and transgenic approaches and provide an opportunity for ?evolutionary? forward genetics. Here I propose to leverage my lab?s extensive experience developing a new vertebrate system from the ground up: highly divergent craniofacial morphology in Caribbean pupfishes. Our preliminary genome-wide divergence scans and association mapping have identified both well-known craniofacial candidate genes and ten new candidate genes associated with jaw length variation. Divergent genomic regions are often restricted to a single gene with only one or a few candidate variants in upstream regulatory or intronic regions. Our preliminary quantitative trait locus mapping also indicates that some of these regions explain up to 15% of jaw length variation in lab-reared F2 intercrosses. Thus, I hypothesize that fixed mutations in these species control spatiotemporal expression of both known and novel craniofacial genes underlying highly divergent craniofacial features in pupfishes. I propose to investigate the genetic basis of novel adaptive phenotypes in this non-model system using a combination of population genomics, de novo genome assembly, quantitative genetics, transcriptomics, in situ hybridization, and CRISPR-Cas9 genome editing. Our initial success in Caribbean pupfishes demonstrates the power of our approach and potential for expansion. Pupfish exhibit novel craniofacial traits; ongoing gene flow and strong selection provide an ideal natural ?experiment? for fine-mapping candidate variants associated with these traits. We are also pioneering in situ hybridization and CRISPR-Cas9 approaches in pupfishes. By integrating candidate gene and variant discovery in a natural system exhibiting diverse craniofacial features with powerful functional assays, the proposed research will demonstrate the feasibility and power of new non-model systems to gain novel insights into the developmental genetics of human diseases. 1

Public Health Relevance

PUBLIC HEALTH RELEVANCE: The proposed research will provide fundamental knowledge of how genes control craniofacial development in vertebrates. This knowledge will help develop therapeutic targets and treatments for human craniofacial diseases. Since the majority of birth defects are craniofacial and dental abnormalities, this research will lead to improved diagnosis, treatment, and prevention of human birth defects. 1

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Research Project (R01)
Project #
1R01DE027052-01A1
Application #
9595848
Study Section
Skeletal Biology Development and Disease Study Section (SBDD)
Program Officer
Stein, Kathryn K
Project Start
2018-08-01
Project End
2023-05-31
Budget Start
2018-08-01
Budget End
2019-05-31
Support Year
1
Fiscal Year
2018
Total Cost
Indirect Cost
Name
University of North Carolina Chapel Hill
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
608195277
City
Chapel Hill
State
NC
Country
United States
Zip Code
27599