Transcriptomics Profiling of Vertebral Fusion in Evolution and Development

During normal maturation of the spine, vertebrae fuse together to form the sacrum in the pelvic girdle. In birds, spine fusion is more extensive, with approximately half of the vertebrae are fused into compound bony structures. Increased fusion in birds arose during evolution as an adaptation for flight.

The biological mechanisms responsible for normal vertebral fusion are largely unknown. However, using the chicken as a model organism, the PI made the surprising discovery that sterile inflammation drives fusion in the tail. Inflammation is generally a response to disease or trauma, but here the PI uncovered a novel role for sterile inflammation in normal bone development.

The PI inhibited inflammation with corticosteroids, and found that this treatment inhibits tail fusion, demonstrating a previously unknown effect of corticosteroids on spine maturation. The implications for these findings are vast, not just for avian evolution but for axial development across vertebrates, and for the possible side effects of corticosteroid treatment in humans.

For this project, the PI will determine whether inflammation is a common driver of normal vertebral fusion, or whether multiple mechanisms have evolved for this process. Additionally, as part of a long-standing collaboration, the PI will link the genomics capabilities of Montana State University and Clemson University.

This Research Infrastructure Improvement Track-4 EPSCoR Research Fellows (RII Track-4:NSF) project would provide a fellowship to an Assistant Research Professor at Montana State University (MSU). This work would be conducted in collaboration with researchers at Clemson University. The goals of this proposal are to receive transcriptomics training, to test the hypothesis that sterile inflammation is a universal driver of vertebral fusion, and to promote Clemson University’s genomics facility to Montana State University researchers.

The PI will compare the transcriptional profiles of fusing chicken synsacrum intervertebral disc tissues to caudal non-fusing tissue by whole transcriptome RNAseq. Specifically, the PI will investigate the potential contributions of nucleus pulposus disc structures and inflammatory response to fusion in different axial regions of the chicken. These data will assess if ankylosis occurs via common or independent mechanisms, and will lend insight into avian axial evolution.

Clemson University is ideal for these studies not only for its genomics facility, but also for its poultry farm, one of the few research poultry centers in academia. Training will include RNA extraction methods and bioinformatics analysis, including GO and KEGG profiling. The expertise gleaned from this collaboration will be applied to an RNAseq instructional module that will be built for MSU researchers to utilize Clemson’s genomics facility.

MSU currently offers microarray, but not RNAseq services. These proposed studies will allow the PI to resolve vertebral fusion mechanism(s) in birds and ultimately expand the PI’s investigations to normal and pathological fusion in a variety of vertebrates, including mammalian disease models. Undergraduate mentorship and public education of science are deeply rooted in this project.

The PI will continue to train existing students, recruit additional undergraduates, and pursue multiple and varied outreach efforts.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.