Gene Trapping: A Powerful Tool of Functional Genomics to Identify Novel Genes

Gene trapping is a type of insertional mutagenesis that disrupts gene function by the integration of a vector in the intergen eric sequences. It provides an important and unique method for studying the relationship between gene expression and function and a powerful tool to characterize novel genes and analyze their importance in biological phenomena. It is performed with gene trap vectors that simultaneously mutate and report the expression of the endogenous gene at the site of insertion. Based on the component of gene expression cassette which they exploit, trap vectors are classified as: enhancer tr ap vectors, promoter trap vectors, gene trap vectors, poly A trap vectors and secretory trap vectors. Vectors are introduced in embryonic stem cells in mice and leaves or floral parts in case of plants by electroporation or virus-mediated transformation. The transformed cells are selected on the basis of selectable markers. Insertion events are detected and the trapped lines are established. This technique has been used to identify tissue specific and temporally regulated genes in plants and mice. It proves to be a powerful tool of functional genomics.