Genome-wide CRISPR screening of genes and pathways for insect cell responding to abnormal environmental pH

Cells are bathed in the extracellular fluids in which the extracellular pH (pHe) is maintained to a narrow range, and abnormal pHe is related to multiple diseases. However, the genes and signaling pathways underlying cell response to abnormal pHe remain unclear. Identification of genes responsive to extreme pHe challenge has great value in both basic research and medicine. Here, we performed genome-wide CRISPR screening to reveal genes and pathways related to insect cell response to abnormal pHe. Cells of the Bombyx mori embryonic cell line (BmE) genome-scale CRISPR screening cell library (BmEGCKLib) were cultured in different pHe (the physiological pH 6.3 as control; pH 5.0, 5.5, 6.6 and 6.95 as abnormal pHe). In the four extreme pH groups, we identified 44 overlapped fitness genes and 24 overlapped positive selected genes respectively. We also performed Kyoto Encyclopedia of Genes and Genomes pathways enrichment analysis for the selected genes. The "phosphatidylinositol signaling system", "mRNA surveillance pathway" and "spliceosome pathway" were significantly enriched in the negative selection, suggesting that cellular signal transduction and mRNA quality play essential roles for cells to resist to abnormal pHe. This is the first time to provide insight into insect cell response to abnormal pHe on a genome-scale.