Finding the perfect promoter: Correlating single-cell transcriptome data with gene drive performance

Gene drive can control pathogen transmission or suppress vector populations by spreading drive alleles with super-Mendelian inheritance. CRISPR homing drive currently represents the most powerful type, and regulating Cas9 expression with specific promoters has been effective for improving drive performance. However, selecting these is often a major challenge. Here, we evaluated 35 Cas9 constructs driven by distinct promoters in different gene drive systems and identified associations between drive performance and single-cell RNA expression patterns of the promoter-associated genes. Our results indicate that higher drive conversion is significantly associated with elevated expression of the promoter-associated gene in the respective reproductive cells, but embryo resistance allele formation correlates with excessive female germline expression. For males, early germline expression produces superior performance. Thus, we find that optimal drive performance requires restricting Cas9 expression to a tight quantitative and spatiotemporal window. In addition, found that in situ integrated rhino-Cas9 constructs significantly reduce somatic expression, underscoring the importance of genomic locus. On the basis of these results, we propose criteria for selecting promoters, providing a theoretical rationale and practical guidance for optimization of promoter elements in homing gene drive systems.