Laura C Bridgewater, Microbiology and Molecular Biology

Work in the Bridgewater Lab over the last several years has focused on elucidating the function of a novel protein we discovered, nBmp2. The initial discovery presenting work performed in cultured cells (rather than whole animals) was published back in 2010 and we subsequently constructed a mutant mouse line in which nBmp2 is disrupted. Much evidence was accumulating to show that the mice have problems with muscle function, neurological function, and immune function, but some fundamental experiments necessary to validate the mouse model had been giving us problems. The absence of that data prevented us from publishing any reports on the various phenotypes in the animal model. Therefore, the whole focus of this MEG project was to validate the nBmp2 mutant mouse model so that publication of four papers could move forward.

Over the past year, several different students have worked on the project. Success was finally achieved, and the first nBmp2 mouse model paper was accepted for publication in BioMed Research International at the end of 2013. The key piece of data for this paper was obtained by undergraduates Megan Whitt and Spencer Dean, who performed immunohistochemistry staining of muscle tissue from nBmp2 mutant mice and showed for the first time that nBmp2 is detectable in muscle tissue, and that the targeted mutation eliminated it. In addition, Joshua Yates performed a PCR-based analysis of the mutant animal’s genome to verify that a key piece of genetic recombination happened as expected and that data is included in the paper.

This recent success has opened the way for at least two other publications and created great enthusiasm in the lab. Megan and Spencer went on to perform immunohistochemistry staining of mouse brain tissue. They ran into technical difficulties, however, and we ended up collaborating with Dr. Jeff Edwards in the PDBIO department and one of his graduate students, Lindsey Friend, to complete the histology work on brain tissue. We found that nBmp2 is detectable in the nuclei of hippocampal neurons and is absent in nBmp2 mutant mice. This is consistent with their impaired performance on tests of spatial and object recognition memory, cognitive function that are centered in the hippocampus. This work was submitted for publication to BMC Neuroscience, but reviewers requested additional behavioral experiments to verify the cognitive impairment. Those studies will be performed after I return from sabbatical in the spring of 2015, and the paper will be resubmitted for publication. The third manuscript resulted from a study of immune function in nBmp2 mutant mice. Graduate student Daniel Olsen, working with several undergraduate students and also with immunologists Dr. Eric Wilson and Dr. Scott Weber, showed that exposure of nBmp2 mutant mice to a bacterial infection makes them more vulnerable (rather than immune) the second time they encounter the bacteria. This paper has been submitted for publication and is currently in revision prior to resubmission. In addition, other students in my lab have worked on osteoarthritis and intervertebral disc degeneration projects, which have resulted in two other publications and have strengthened the mentoring environment in my lab.

Below are lists of papers published and near publication, and of posters presented at scientific meetings, which have resulted from mentoring in my lab since this MEG grant was awarded. BYU student authors are underlined to emphasize the number of students who have benefited from this mentoring.

Publications

1. Ricks, M.S., Farrell, J.T., Falk, D.J., Holt, D.W., Rees, M., Carr, J., Williams, T., Nichols, B.A., Bridgewater, L.C., Reynolds, P.R., Kooyman, D.L., & Seegmiller, R.E. “Osteoarthritis in the temporomandibular joint of Col2a1 mutant mice.” Archives of Oral Biology. 58:1092-1099 (2013).
2. Bridgewater, L.C., Mayo, J.L., Evanson, B.G., Whitt, M.E., Dean, S.A., Yates, J.D., Holden, D.N., Schmidt, A.D., Fox, C.L., Dhunghel, S., Steed, K.S., Adam, M.M., Nichols, C.A., Loganathan, S.K., Barrow, J.R., Hancock, C.R. “A novel bone morphogenetic protein 2 mutant mouse, nBmp2NLStm, displays impaired intracellular Ca2+ handling in skeletal muscle.” BioMed Research International. Volume 2013, article ID 125492 http://dx.doi.org/10.1155/2013/125492 (2013).
3. Stolworthy, D.K., Fullwood, R.A., Merrell, T.M., Bridgewater, L.C., & Bowden, A.E. “Biomechanical comparison of the camelid and human intervertebral disc.” Journal of Orthopaedic Translation, In press.
4. Cordner, R.D., Mayo, J.L., Badgley, C., Wallmann, A., Whitt, M.E., Dean, S.A., Ventura, J.S., Chidsey, B.A., Rogers, A.C., Barrow, J.R., Edwards, J.G. Bridgewater, L.C. “A novel mouse model bearing a targeted mutation of nuclear bone morphogenetic protein 2 (nBMP2) develops impaired memory.” In revision.
5. Olsen, D.S., Bailey, T., Merriam, K.M., Goar, W., Wilson, E., Weber, S., Bridgewater, L.C. “The nuclear variant of BMP2, nBMP2, affects immune cell activation.” In revision.

Posters

1. Yates, J.D. Bridgewater, L.C. “Evidence for a nuclear variant of decapentaplegic (dpp).” Southwest Regional Meeting of the Society for Developmental Biology. Aurora, CO (2014).
2. Mayo, J.L., Nichols, B.A., Olsen, D.S., Cordner, R.D., Hancock, C.R., Weber, K.S., Wilson, E., Edwards, J.G., Barrow, J.R., and Bridgewater, L.C. “The nBMP2 mutant mouse shows defects in intracellular calcium transport-regulated pathways.” Southwest Regional Meeting of the Society for Developmental Biology. Aurora, CO (2014).
3. Bridgewater, L.C., Christensen, S.L. Stolworthy, D.K., Fullwood, R.A., Merrell, T.M., Holland J.G., Harmon, L.M., Robinson, T., Bowden, A.E. “Development of an alpaca disc culture system for the study of intervertebral disc degeneration.” Second International Spine Research Symposium, Philadelphia Spine Research Society. Philadelphia, PA (2013).
4. Stolworthy, D.K., Fullwood, R.A., Merrell, T.M., Bowden, A.E., Bridgewater, L.C. “Mechanical paralleles for a camelid cervical spine model of lumbar disc degeneration.” Second International Spine Research Symposium, Philadelphia Spine Research Society. Philadelphia, PA (2013).
5. Fullwood, R.A., Stolworthy, D.K., Bowden, A.E., and Bridgewater, L.C. “Alpaca cervical spine anatomy: Shape, size, AF/NP ratio.” Emerging Ideas in Biomedical Research Conference, BYU, Provo, UT (2013). Amy Fullwood won the 1st place prize in the poster competition.
6. Christensen, L., Holland, J.G., Fullwood, R.A., Stolworthy, D.K., Bowden, A.E., Robinson, T.F., and Bridgewater, L.C. “Development of an alpaca disc culture system for the study of intervertebral disc degeneration.” Emerging Ideas in Biomedical Research Conference, BYU, Provo, UT (2013). Loyd Christensen won the 2nd place prize in the poster competition.
7. Olsen, D.S., Bailey, K.T., Nichols, B.A., and Bridgewater, L.C. “Lack of nuclear BMP-2 causes reduced spleen size.” American Society for Biochemistry and Molecular Biology Annual Meeting, Boston, MA (2013).
8. Nichols, B.A., Goar, W.A., McCune, B.T., and Bridgewater, L.C. “Nuclear localized BMP2 promotes cell cycle progression. American Society for Biochemistry and Molecular Biology Annual Meeting, Boston, MA (2013).

Summary of Spending

• The budget for this project was spent primarily on supplies and animal care costs, as follows:
• Animal care costs, WIDB mouse facility ($10,000)
• PCR enzymes and primers for genotyping the mice ($2,000)
• Tissue preparation and sectioning ($500)
• Antibodies for immunostaining and microscope hourly use charges ($2,000)
• Tissue culture media, serum, flasks, and transfection reagents ($4,000)
• Microbiological plates and culture media ($500) • Western blot reagents ($1,000)