Graduate Program in Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, USA.
Department of Clinical Pharmacy and Translational Science, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, USA.
mSphere. 2024 Mar 26;9(3):e0069523. doi: 10.1128/msphere.00695-23. Epub 2024 Feb 13.
is a major invasive mold pathogen and the most frequent etiologic agent of invasive aspergillosis. The currently available treatments for invasive aspergillosis are limited in both number and efficacy. Our recent work has uncovered that the β-glucan synthase inhibitors, the echinocandins, are fungicidal against strains of with defects in septation initiation network (SIN) kinase activity. These drugs are known to be fungistatic against strains with normal septation. Surprisingly, SIN kinase mutant strains also failed to invade lung tissue and were significantly less virulent in immunosuppressed mouse models. Inhibiting septation in filamentous fungi is therefore an exciting therapeutic prospect to both reduce virulence and improve current antifungal therapy. However, the SIN remains understudied in pathogenic fungi. To address this knowledge gap, we characterized the putative regulatory components of the SIN. These included the GTPase, SpgA, it's two-component GTPase-activating protein, ByrA/BubA, and the kinase activators, SepM and MobA. Deletion of , or resulted in no overt septation or echinocandin susceptibility phenotypes. In contrast, our data show that deletion of or largely phenocopies disruption of their SIN kinase binding partners, and , respectively. Reduced septum formation, echinocandin hypersusceptibility, and reduced virulence were generated by loss of either gene. These findings provide strong supporting evidence that septa are essential not only for withstanding the cell wall disrupting effects of echinocandins but are also critical for the establishment of invasive disease. Therefore, pharmacological SIN inhibition may be an exciting strategy for future antifungal drug development.IMPORTANCESepta are important structural determinants of echinocandin susceptibility and tissue invasive growth for the ubiquitous fungal pathogen . Components of the septation machinery therefore represent promising novel antifungal targets to improve echinocandin activity and reduce virulence. However, little is known about septation regulation in . Here, we characterize the predicted regulatory components of the septation initiation network. We show that the kinase activators SepM and MobA are vital for proper septation and echinocandin resistance, with MobA playing an essential role. Null mutants of displayed significantly reduced virulence in a mouse model, underscoring the importance of this pathway for pathogenesis.
是一种主要的侵袭性霉菌病原体，也是侵袭性曲霉菌病最常见的病因。目前用于侵袭性曲霉菌病的治疗方法在数量和疗效上都很有限。我们最近的工作发现，β-葡聚糖合酶抑制剂——棘白菌素类，对有缺陷的隔膜起始网络（SIN）激酶活性的菌株具有杀菌作用。众所周知，这些药物对具有正常隔膜的菌株具有抑菌作用。令人惊讶的是，SIN 激酶突变株也未能侵入肺部组织，在免疫抑制的小鼠模型中其毒力显著降低。因此，抑制丝状真菌的隔膜形成是减少毒力和改善当前抗真菌治疗的一个令人兴奋的治疗前景。然而，SIN 在致病性真菌中研究不足。为了弥补这一知识空白，我们对 的假定调节成分进行了表征。这些成分包括 GTPase SpgA、它的双组分 GTPase 激活蛋白 ByrA/BubA 以及激酶激活剂 SepM 和 MobA。缺失 、 或 并没有导致明显的隔膜或棘白菌素敏感性表型。相比之下，我们的数据表明，缺失 或 分别主要模拟了其 SIN 激酶结合伙伴 和 的破坏。任一基因的缺失都会导致隔膜形成减少、棘白菌素超敏反应和毒力降低。这些发现为隔膜不仅对棘白菌素破坏细胞壁的影响具有重要作用，而且对侵袭性疾病的建立也具有重要意义提供了强有力的证据。因此，药理学上抑制 SIN 可能是未来抗真菌药物开发的一个令人兴奋的策略。重要性隔膜是普遍存在的真菌病原体 对棘白菌素敏感性和组织侵袭性生长的重要结构决定因素。隔膜形成机制的成分因此代表了有前途的新型抗真菌靶标，可以提高棘白菌素的活性并降低毒力。然而，对于 中的隔膜调节知之甚少。在这里，我们对 的隔膜起始网络的预测调节成分进行了表征。我们表明，激酶激活剂 SepM 和 MobA 对正确的隔膜形成和棘白菌素抗性至关重要，其中 MobA 起着至关重要的作用。 的缺失突变株在小鼠模型中表现出明显降低的毒力，这突出了该途径对 发病机制的重要性。
