PDF(Pubmed)
Abstract：
Gene drive systems could be a viable strategy to prevent pathogen transmission or suppress vector populations by propagating drive alleles with super-Mendelian inheritance. CRISPR-based homing gene drives convert wild type alleles into drive alleles in heterozygotes with Cas9 and gRNA. It is thus desirable to identify Cas9 promoters that yield high drive conversion rates, minimize the formation rate of resistance alleles in both the germline and the early embryo, and limit somatic Cas9 expression. In Drosophila, the nanos promoter avoids leaky somatic expression, but at the cost of high embryo resistance from maternally deposited Cas9. To improve drive efficiency, we test eleven Drosophila melanogaster germline promoters. Some achieve higher drive conversion efficiency with minimal embryo resistance, but none completely avoid somatic expression. However, such somatic expression often does not carry detectable fitness costs for a rescue homing drive targeting a haplolethal gene, suggesting somatic drive conversion. Supporting a 4-gRNA suppression drive, one promoter leads to a low drive equilibrium frequency due to fitness costs from somatic expression, but the other outperforms nanos, resulting in successful suppression of the cage population. Overall, these Cas9 promoters hold advantages for homing drives in Drosophila species and may possess valuable homologs in other organisms.
摘要：
基因驱动系统可能是通过传播具有超孟德尔遗传的驱动等位基因来防止病原体传播或抑制载体种群的可行策略。基于CRISPR的归巢基因驱动将野生型等位基因转化为具有Cas9和gRNA的杂合子中的驱动等位基因。因此，需要鉴定产生高驱动转化率的Cas9启动子，将种系和早期胚胎中抗性等位基因的形成率降至最低，和限制体细胞Cas9表达。在果蝇中,nanos启动子避免了泄漏的体细胞表达，但是以母本沉积的Cas9的高胚胎抗性为代价。为了提高驱动效率，我们测试了11个果蝇种系启动子。一些以最小的胚胎阻力实现更高的驱动转换效率，但没有人完全避免体细胞表达。然而,这种体细胞表达通常不会携带针对单倍致死基因的救援归巢驱动的可检测的适应性成本，暗示躯体驱动转换。支持4-gRNA抑制驱动，由于体细胞表达的适应性成本，一个启动子导致低驱动平衡频率，但是另一个胜过纳米，成功抑制了笼子的数量。总的来说,这些Cas9启动子在果蝇物种中具有归巢驱动的优势，并且在其他生物体中可能具有有价值的同源物。
