The expression and regulation of the single calmodulin gene of Drosophila melanogaster

[摘要] Calcium and calmodulin-based regulation of cell activity is one of the most widespread signaling mechanisms in eukaryotic organisms. Extensive experimentation has uncovered many diverse roles for calcium signals, many of which involve calmodulin. Calmodulin interacts with and regulates a large and growing number of target proteins. For most of these targets, interaction with calcium-bound calmodulin results in activation of the target protein. In addition to regulating numerous proteins directly, several calmodulin targets are also multifunctional regulators such as kinases and phosphatases. Thus, Ca$sp{2+}$-calmodulin-based signaling is a powerful regulator of cell activities.Consistent with its importance in cellular processes, calmodulins from diverse eukaryotic species show remarkably high conservation at the amino acid level, typically being greater than 90% identical. This strong conservation and the discovery that Drosophila calmodulin is encoded by a single gene make Drosophila melanogaster particularly well suited for the study of the role of calmodulin in a multicellular organism.The experiments presented here examine the expression of the single calmodulin gene of Drosophila at the levels of mRNA and protein. In situ hybridizations to post-embryonic stages of Drosophila development reveal a complex pattern of calmodulin gene expression, as was suggested by previous examination of calmodulin transcript expression during embryogenesis. Some tissues such as the gut appear to have a greater need for calmodulin transcripts when they are highly active, while others, such as the musculature have higher calmodulin mRNA levels during their formation. The central nervous system produces high amounts of calmodulin mRNA during periods of inactivity that appear to be required for later function instead of immediate uses. Immunolocalization and immunoblotting experiments suggest the possibility of translational regulation of calmodulin protein levels in the central nervous system and indicate low turnover of calmodulin protein during most of embryogenesis. The expression and localization of calmodulin suggests roles for calmodulin in the regulation of neural function, mitosis and cell division cycles, cytoskeletal dynamics and cell shape changes, and secretion.

[发布机构] Rice University

[效力级别] biology