The knocked out cells will answer all the questions
Scientists at the Whitehead Institute for Biomedical Research, working under the leadership of Dr. Thijn R. Brummelkamp, have developed a new method of genetic screening of human cells in order to identify specific genes and their protein products used by pathogens of infectious diseases. The results of the work were published on November 27 in the journal Science in the article "Haploid Genetic Screens in Human Cells Identify Host Factors Used by Pathogens".
In almost all cultured human cells, genes are represented by two copies, one of which is inherited from the mother, and the second from the father. In many cases, this ensures the normal operation of diploid (having two pairs of each chromosome) cells even when one of the genes is "broken" as a result of mutation, since the second copy of the gene, as a rule, remains active and synthesizes a sufficient amount of the corresponding protein.
One of the methods of studying the functions of genes is knockout, in which both copies of the gene are completely removed or rendered inoperable as a result of mutations. To facilitate this task, the authors chose as the object of their research an "almost haploid" line of human cells in which all chromosomes, except the eighth, are represented by a single copy.
The authors alternately caused mutations of almost all genes of this cell line and used the collection of cells obtained in this way for screening in order to search for genes that provide sensitivity to pathogens. Exposure of cells to the influenza virus allowed them to isolate mutant cells resistant to it. After that, the researchers identified the mutant genes of the surviving cells encoding the carrier molecule and the enzyme that the virus uses to capture the cell.
They also exposed the cells to bacterial toxins, as a result of which they identified a previously unknown gene, the protein product of which plays a major role in intoxication with diphtheria toxin and exotoxin A (secreted by Pseudomonas aeruginosa), as well as a cell surface protein necessary for the manifestation of toxicity of cytoletal stretching (loosening) toxin (secreted by pathogenic strains of E. coli).
According to the first author of the article, Jan Carette, the clarity of the results was simply amazing. They allowed scientists to identify previously unknown genes and proteins involved in infectious processes that have been studied for decades, such as influenza and diphtheria. In addition, they were able for the first time to identify human genes involved in the mechanisms of the relationship between the host organism and the pathogen that are poorly understood to date. This knowledge can play an important role in the development of means to combat previously unknown pathogens, as well as in the study of the biology of pathogens with which, for some reason, it is impossible to conduct experimental work.
Brummelkamp considers this work to be the beginning of a new research direction in genomics and proteomics, since access to a collection of human cells knocked out for almost every gene will not only identify cellular proteins that are targets for various viruses and bacteria, but also get answers to a huge number of questions about cell biology.
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of Science Daily: Knockouts in Human Cells Point to Pathogenic Targets.
01.12.2009