A Genome-Wide Screening of Potential Target Genes to Enhance the Antifungal Activity of Micafungin in <i>Schizosaccharomyces pombe</i>

Micafungin is a non-reversible inhibitor of 1, 3-β-D-glucan synthase and interferes with fungal cell wall synthesis. Clinically, micafungin has been shown to be efficacious for the treatment of invasive candidiasis and invasive aspergillosis. However, considering its relatively restricted antifungal spectrum, combination therapy with micafungin plus other agents should be considered in critically ill patients. To identify potential therapeutic targets for syncretic drug combinations that potentiate micafungin action, we carried out a genome-wide screen for altered sensitivity to micafungin by using the model yeast Schizosaccharomyces pombe mutant library. We confirmed that 159 deletion strains in the library are micafungin sensitive and classified them into various functional categories, including cell wall biosynthesis, gene expression and chromatin remodeling, membrane trafficking, signaling transduction, ubiquitination, ergosterol biosynthetic process and a variety of other known functions or still unknown functions. On the other hand, we also investigated the growth inhibitory activities of some well-known drugs in combination with micafungin including antifungal drug amphotericin B, fluconazole and immunosuppressive drug FK506. We found that amphotericin B in combination with micafungin showed a more potent inhibitory activity against wild-type cells than that of micafungin alone, whereas fluconazole in combination with micafungin did not. Also, the immunosuppressive drug FK506 showed synergistic inhibitory effect with micafungin on the growth of wild-type cells, whereas it decreased the inhibitory effect of micafungin in Δpmk1 cells, a deletion mutant of the cell wall integrity mitogen-activated protein kinase (MAPK) Pmk1. Altogether, our findings provide useful information for new potential drug combinations in the treatment of fungal infections.米卡芬净（Micafungin）是1,3-β-D-葡聚糖合酶的不可逆抑制剂，可干扰真菌细胞壁的合成。临床研究证实，米卡芬净对侵袭性念珠菌病与侵袭性曲霉病具有确切治疗效果。然而，鉴于其抗真菌谱相对狭窄，重症患者需考虑采用米卡芬净联合其他药物的治疗方案。为筛选可增强米卡芬净药效的联合治疗潜在靶点，本研究以模式酵母粟酒裂殖酵母（Schizosaccharomyces pombe）突变体文库为工具，开展全基因组水平的米卡芬净敏感性筛选实验。本研究共验证得到文库中159株对米卡芬净敏感的缺失菌株，并将其划分为多个功能类别，包括细胞壁生物合成、基因表达与染色质重塑、膜泡运输、信号转导、泛素化过程、麦角固醇生物合成通路，以及多种其他已知或未知功能类别。此外，本研究还考察了部分经典药物与米卡芬净联合使用的生长抑制活性，涉及抗真菌药物两性霉素B（amphotericin B）、氟康唑（fluconazole）以及免疫抑制剂FK506。研究发现，两性霉素B与米卡芬净联合使用时，对野生型酵母细胞的抑制活性较米卡芬净单药更为显著；而氟康唑与米卡芬净联合则未呈现此类协同增强效果。免疫抑制剂FK506与米卡芬净联用可对野生型细胞生长产生协同抑制效应，但会削弱米卡芬净对Δpmk1细胞——即细胞壁完整性丝裂原活化蛋白激酶（MAPK）Pmk1的缺失突变体——的抑制作用。综上，本研究结果为开发治疗真菌感染的新型潜在联合用药方案提供了有价值的参考依据。