Beschreibung:
<jats:title>Abstract</jats:title>
<jats:p>Unbiased loss-of-function genetic screens in model organisms have been major driving forces for modern biological research. However, many biological functions of humans such as adaptive immunity are not found in model organisms amenable to classic genetic screens. Despite tremendous efforts, human somatic cell genetics remains unattainable due to the inability to efficiently induce homozygous mutations in diploid human cells. Our group developed a novel haploid genetics approach to dissect immune pathways in human cells. We take advantage of human myeloid cells lines (e.g. KBM7) that exhibit a haploid karyotype. Retroviral insertional mutagenesis of the haploid cells generates a library of mutant cells with individual genes completely disrupted. First, we validated the haploid mutant library by screening for mutants resistant to the cytotoxicity of diphtheria toxin. After selection, the retroviral insertion sites of the resistant clones were mapped by deep sequencing. We identified HBEGF, the known cell surface receptor for diphtheria toxin. We also isolated multiple endocytic membrane proteins, which likely mediate the internalization of diphtheria toxin. Next, we demonstrated that the haploid mutant library is also suitable for studying complex immune pathways such as the elimination of tumor cells by cytotoxic T lymphocytes. This haploid genetics approach provides a novel and powerful platform for dissecting immune pathways on a genome-wide scale.</jats:p>