Highly proficient gene targeting by homologous recombination in the human pre-B cell line Nalm-6

Gene targeting provides a powerful means for studying gene function by a reverse genetic approach. Despite recent rapid progress in gene knockdown technologies, gene knockout studies using human somatic cells will be of greater importance for analyzing the functions of human genes in greater detail. Although the frequency of gene targeting is typically very low in human cultured cells, we have recently shown that a human precursor B cell line, Nalm-6, exceptionally allows for high-efficiency gene targeting by homologous recombination. In addition, we have developed a quick and simplified method to construct gene-targeting vectors, which is applicable to all sequenced organisms as well as embryonic stem cells. The combination of the simplified vector construction technology and the highly efficient gene-knockout system using Nalm-6 cells has enabled us to disrupt virtually any locus of the human genome within one month. Our system will greatly facilitate gene-knockout studies in human cells.