The potential benefits of insulators on heterologous constructs in transgenic animals

Abstract

Transgenes can display position effects, shown as variegated, ectopic, uncontrolled and even silenced expression. These undesired side effects result in irreproducible and non-systematic expression patterns in transgenic animals. The use of artificial-chromosome type constructs has been shown to overcome these position effects (Giraldo & Montoliu, 2001). However, in a large proportion of experiments with transgenic animals, constructs are made by fusing the coding region of a given gene under the control of heterologous promoter and regulatory sequences, with the aim that the expression pattern of the heterologous gene would be faithfully reproduced by the transgenic chimeric construct. In this context, the lack of endogenous regulatory sequences that are required for establishing a proper expression domain, often result in poorly controlled and suboptimally expressed transgenes (Montoliu, 2002).