Functional elimination of calmodulin within the nucleus by targeted expression of an inhibitor peptide.

Genetic manipulation has proven valuable in identifying the role of specific genes in cellular function. Genomic disruption of genes that are expressed during embryonic development or in multiple tissue types, however, complicates phenotypic analysis. We demonstrate that targeted expression of an inhibitor peptide derived from myosin light chain kinase can neutralize the function of calmodulin. We have shown that elimination of the nuclear function of Ca(2+)-calmodulin causes disruption of the nuclear structure. Targeted expression of this calmodulin inhibitor gene in the lung epithelium of transgenic mice leads to cellular death and dysfunctional lung development. This approach is a strategy to modify the activity of a targeted protein within a specific organelle in order to evaluate its role in cellular and tissue function.