Research interests

Calcium ions are used asmessenger molecules that regulate many important intracellularprocesses. We need to learn how calcium’s ‘messages’ are interpreted bycells in order to understand how cells move, divide, grow, becomecancerous, or die. A variety of calcium binding proteins function torespond to calcium’s ‘message’ and my work is focussed on one family ofthese proteins; the proteolytic enzymes called calpains. The CALPAIN websitehas a picture of the enzyme structure and information about the variousisoforms. Calpains are ubiquitously present in eukaryotic cellsincluding nematodes, fruit flies and humans. These enzymes must dosomething very important as their absence is lethal during thedevelopment of mouse embryos.  This was shown by targeted deletionof the capn4 or capn 2 gene.

The family of calpains may be as large as 15 –20 enzymes although only 3 or 4 have been studied in any detail. Genetic studies have linked several novel calpains to specific disease processes. For example malfunction of calpain-3 is the cause of an inherited disease, Limb-Girdle muscular dystrophy (type IIA) . Loss of calpain-9 is linked to oncogenesis and variations in calpain-10 were identified as a risk factor for type 2 diabetes.

Calpains are also therapeutic targets for drug development due to evidence linking them to neurodegenerative diseases and in some pathways related to cancer. Over the past 20 years my laboratory has made significant contributions to our understanding of the biochemistry of calpain-1 and calpain –2 and the protein calpastatin that specifically inhibits these enzymes. Ongoing studies continue to investigate how calpains’ protein structure relates to their catalytic function and regulation.

We are also interested in exploiting the biochemistry of these proteins to learn why these enzymes are important physiologically. We continue to work towards identifying how calpains are regulated in vivo and what proteins they cleave. We have recently initiated experiments to look at calpain expression and function using zebrafish, studies made possible by the construction of a zebrafish ‘farm’ in Hitchner Hall. Zebrafish will provide the opportunity to investigate isoform specific calpain expression and function in a living vertebrate organism. These studies are expected to provide important information about the physiological roles of this family of enzymes.

Publications

• Dutt, P., Croall, D.E., Arthur, J.S.C., DeVeyra, T., Williams, K. Elce, J.S. and Greer, P. (2004) Calpain is required for preimplantation embryonic development in mice. Ms. In preparation
• Croall, D.E. and Hatch, H. (2004) The regulation of calpain activity by calcium: a role for an IQ-motif. Ms in preparation.
• Croall, D.E. , Moffett, K. and Hatch, H. (2002) Casein zymography of calpains using a 4- (2-hydroxtethyl)-1-piperazineethnesulfonic acid- Imidiazole buffer. Analytical Biochemistry 304, 129-132
• Croall, D.E. (2000) Affinity chromatography methods for purifying calpains. in Methods in Molecular Biology 144, 33-40.
• Hosfield, C.M., Ye, Q., Arthur, J.S.C., Hegadorn, C., Croall, D.E., Elce, J.S., Jia, Z. (1999) Crystallization and X-ray crystallographic analysis of m-calpain, a calcium-dependent protease. Acta Cryst. D55, 1484-1486
• Dutt, P., Arthur, J.S.C., Croall, D.E. and Elce, J.S. (1998) m-calpain subunits remain associated in the presence of calcium. FEBS Lett. 436, 367-371.
• Potter, D.A., Tirnauer, J.S., Jansenn, R., Croall, D.E., Hughes, C.N., Mier, J., Maki, M. and Herman, I.M. (1998) Calpain regulates cell spreading and function of the cortical actin cytoskeleton. J. Cell Biol. 141, 647-662.
• Arora, A.S., deGroen, P., Croall, D.E., Emori, Y., and Gores, G. (1996) Hepatocellular carcinoma cells resist necrosis during anoxia by preventing phospholipase mediated calpain activation. J. Cellular Physiology. 167: 434-442.
• Croall, D.E., Chacko, S. and Wang, X. (1996) Cleavage of caldesmon and calponin by calpain: Substrate recognition is not dependent on calmodulin binding domains. Biochim. Biophys. Acta 1298: 276-284. . Biochim. Biophys. Acta 882:287-296.
• Spencer, M.J., Croall, D.E. and Tidball, J.G. (1995) Calpains are activated in necrotic fibers from mdx dystrophic mice. J. Biol. Chem. 270: 10909 - 10914.
• Croall, D.E. and McGrody, K.S. (1994) The domain structure of milli-calpain: Mapping the binding site for calpastatin. Biochemistry 33: 13223-13230.
• Potts, A.J., Croall, D.E. and Hemler , M.E. (1994) Proteolytic cleavage of the Integrin ?4 subunit. Exp. Cell. Res. 212: 2-9.

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