Controlling when and where: Conditional and inducible gene expression
Abstract : To truly study the function and mechanisms of gene expression, simple over-expression or constitutive knockouts are not completely sufficient; particularly when embryonic lethality can occur. To over come these limitations and better understand gene function, inducible, conditional, spatial, and temporal gene expression can be achieved through a variety of approaches. From tissue specific promoters to recombinase ba'gene switches', many tools are available to control when, where, and how genes of interest are expressed. In the early days of engineered animal models, simple knockout and transgenic mice were used to examine gene function. Researchers began to dissect the roles of individual genes by studying phenotypes of mice lacking or overexpressing specific genes. However, constitutive knockouts and transgenics are not adequate for analyzing the function of many genes. For example, genes with important functions in adult animals may be embryonic lethal when