Warner, Alden H.Contact Information
B.A. (Maine), M.A, Ph.D. (Southern Illinois)
Molecular Regulation of Developmental
Office Location: Biology Building - 221
Tel: (519) 253-3000 ext. 2728 (office),
Fax: (519) 971-3609
Developmental events in multicellular organisms requires a complex set of intracellular and intercellular reactions that are often mediated by proteolytic enzymes or proteases. Among the four major classes of proteases, cysteine proteases have been implicated in several developmental events including gastrulation and remodeling of the extracellular matrix. Among the cysteine proteases, cathepsin L secretion has been shown to be associated with metastasis in mammals and parasite invasion in other organisms. Historically, cysteine proteases were considered to be lysosomal enzymes, but we now know that cysteine proteases such as cathepsin L are present at several non-lysosomal sites including he nucleus of mammalian and non-mammalian cells where it is thought to play a role in gene regulation. Our research has shown that embryos of the brine shrimp Artemia contain a novel heterodimeric cathepsin L consisting of a catalytic subunit (ie., cathepsin L) and non-catalytic subunit which we have named cathepsin L-associated protein or CLAP. CLAP is a fasciclin I containing cell adhesion protein similar to that found in other eukaryotic cells that provides stability to cathepsin L and may be involved in targeting cathepsin L to non-lysosomal sites. We have
characterized genomic and cDNA clones encoding cathepsin L and CLAP in Artemiaand these are available in Genbank through NCBI.
Currently, the main focus of our research program is to study the molecular mechanisms responsible for desiccation tolerance exhibited by encysted embryos of the brine shrimp Artemia. Towards this objective we have identified several heat soluble proteins that are members of the late embryogenesis abundant (LEA) group of proteins, first found in plant seeds in the early 1980's. We are working to characterize the spectrum of LEA proteins found in encysted embryos, and to determine their function in these stress resistant embryos.
We have developed collaborations with other researchers world-wide in studying the role of LEA and other dominant proteins in Artemiaembryos that we believe permit these embryos to enter and/or survive diapause and dormancy characteristic of this crustacean.
Potential Projects for New Students
Characterization of LEA proteins and their genes during development.
Sharon, M.A., Kozarova, A., Clegg, J.S., Vacratsis, P.O. and Warner, A.H. (2009). Characterization of a group 1 late embryogenesis abundant protein in encysted embryos of the brine shrimp Artemia franciscana . Biochem. Cell Biol. 87, 415-430.
Liu, L. and Warner, A.H. (2006). Further characterization of the cathepsin L-associated protein and its gene in two species of the brine shrimp, Artemia. Comp. Biochem. Physiol. 145, 458-467.
Warner, A.H., Pullumbi, E., Amons, R., and Liu, S. (2004). Characterization of a cathepsin L-associated protein in Artemia and its relationship to the FAS-I family of cell adhesion proteins. Eur. J. Biochem. 271, 4014-4025.
Warner, A.H., Brunet, R.T., MacRae, T.H. and Clegg, J.S. (2004). Artemin is an RNA-binding protein with high thermal stability and potential RNA chaperone activity. Arch. Biochem Biophys. 424, 189-200.
Butler, A.M., Aiton, A.L. and Warner, A.H. (2001). Characterization of a novel heterodimeric cathepsin L-like protease and cDNA encoding the catalytic subunit of the protease in embryos of Artemia franciscana. Biochem. Cell Biol. 79, 43-56.
Warner, A.H. and Clegg, J.S. (2001). Diguanosine nucleotide metabolism and the survival of Artemia embryos during years of continuous anoxia. Eur. J. Biochem. 268, 1568-1576.