Elucidating the Role of CaMKK in Cell Cycle and Cell Fate Using a C. elegans Model.
Annual rept. 1 Jul 97-30 Jun 98
DUKE UNIV DURHAM NC
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The mammalian calmodulin-dependent protein kinase kinases CaMKKs have been shown to phosphorylate and activate the calmodulin-dependent protein kinases I and IV CaMKI, CaMKIV, leading to transcription of a variety of genes including c-fos, c-jun and cyclin A. Using a C. elegans homologue ceCaMKK, we are investigating the importance of this proposed cascade to cell cycle, cell fate and development in the context of a well defined multicellular organism. To examine the cell-specific pattern of gene expression, transgenic worms have been generated which express beta-galactosidase or green fluorescent protein under the control of the ceCaMKK promoter. These reporter constructs reveal expression in the excretory cell, vulval muscle cells and several neurons of adult hermaphrodites, as well as hypodermal cells of L1L2 larvae. To compare the C. elegans and mammalian enzymes biochemically, we have cloned and expressed the ceCaMKK protein. Using human CaMKI as a substrate, ceCaMKK is Ca2 calmodulin dependent and phosphorylates CaMKI on threonine 177, the residue phosphorylated by mammalian CaMKKs. These results indicate a functional homology between the mammalian and C. elegans CaMKKs, but further work remains to reveal the biological functions of this family of proteins.
- Medicine and Medical Research