Targeted disruption of a human interferon-inducible gene detected by secretion of human growth hormone.

A new method is described for the sib-selection of 'targeted' mammalian cells that have undergone homologous recombination (HR) with a transfected DNA construct. This method has been used to disrupt the 6-16 gene, an interferon (IFN)-inducible gene of unknown function, in two different human cell lines. Disruption was caused by integration of a targeting construct containing a promoterless gene for human growth hormone (hGH) which was expressed after HR with the 6-16 gene. Homologous recombinants were detected in pools of non-homologous recombinants by the appearance of hGH in the growth medium after the addition of IFN. Secondary and tertiary rounds of hGH assays were used to sib-select 9 homologous recombinants that were shown to have 1, 2 or 3 copies of the targeting construct integrated at the 6-16 locus. The method, which should be applicable to other transcribed targets, provides an alternative to selection methods, and offers advantages over other screening methods in being simple, rapid, sensitive and reliable.