Elucidating tumor necrosis factor signaling pathway using a functional gene identification approach.

Functional identification of genes is an efficient way to study many biological processes in lower eukaryotes. However, an effective approach in mammalian cells is still under development. We designed a functional gene identification procedure and applied it in a study of tumor necrosis factor (TNF)-induced cell killing. This procedure employed a specially designed retroviral vector that allows random truncation of genes, efficiently selecting clones in which a gene was disrupted and quickly identifying disrupted genes. We have identified several novel genes by a preliminary test of this approach and confirmed by reconstitution that the genes we identified are required for TNF cytotoxicity in L929 cells. Because of the efficient identification of these components in TNF-induced cell killing, we have already been able to outline the killing pathway of TNF in L929 cells. Application of this method could be widespread because it can be used in studying any cellular responses if a specific selection assay can be set up.