Thomas R. Shearer, Ph.D.
Professor and Chair
Our lab tested if other trace minerals besides fluoride affected susceptibility to dental caries. Injecting toxic amounts of the essential trace mineral selenium into to very young rats produced profound bilateral cataracts in the eye (1). This rodent model has been used to screen potential drugs against cataracts. The serendipitous finding also lead to discovering a splice mutant of muscle calcium activated protease calpain (Lp82) that is found only in rodent lenses (2,3). Collaborative studies with Senju Pharmaceutical Co. Ltd. have further elucidated the mechanism of action of other calpains in important human eye diseases (4,5), supporting an on-going, early pase clinical trial on the use of calpain inhibitors to prevent human eye disease.
2. Fukiage C, Nakajima E, Ma H, Azuma M, Shearer TR. Characterization and regulation of lens-specific calpain Lp82.
J Biol Chem. 2002 Jun 7;277(23):20678-85.
3. Nakajima T, Shearer TR, Azuma M. Loss of calpastatin leads to activation of calpain in human lens epithelial cells. Invest Ophthalmol Vis Sci. 2014 Jul 22;55(8):5278-83. doi: 10.1167/iovs.14-14778.
4. Suzuki R, Oka T, Tamada Y, Shearer TR, Azuma M. Degeneration and dysfunction of retinal neurons in acute ocular hypertensive rats: involvement of calpains. J Ocul Pharmacol Ther. 2014 Jun;30(5):419-28. doi: 10.1089/jop.2013.0100.
5. Oka T, Walkup RD, Tamada Y, Nakajima E, Tochigi A, Shearer TR, Azuma M Amelioration
of retinal degeneration and proteolysis in acute ocular hypertensive rats by calpain inhibitor
acid 5-methoxy-3-oxapentyl ester. Neuroscience. 2006 Sep 15;141(4):2139-45.
Teaching interests support biochemistry,
nutrition, statistics, and pharmacology. Recent efforts are directed towards developing mock NBDE part 1 and 2
exams at the OHSU School of Dentistry.
Chair, Integrated Biosciences (SD,
present);Interim Chair Biochemistry and Molecular Biology (SM, past),
Associate Dean for Research (SD, past).