Goich David, Bloom Amanda L M, Duffy Sean R, Ventura Maritza N, Panepinto John C
Department of Microbiology and Immunology, Witebsky Center for Microbial Pathogenesis and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, USA.
mBio. 2025 Feb 5;16(2):e0176224. doi: 10.1128/mbio.01762-24. Epub 2024 Dec 13.
The fungus is an opportunistic pathogen of humans that reprograms its translatome to facilitate adaptation and virulence within the host. We studied the role of Hog1/p38 in reprogramming translation during thermal stress adaptation and found that this pathway acts on translation crosstalk with the Gcn2 pathway, a well-studied regulator of general translation control. Using a combination of molecular assays and phenotypic analysis, we show that increased output from the Gcn2 pathway in a Hog1 deletion mutant is associated with rescue of thermal stress adaptation at both molecular and phenotypic scales. We characterize known outputs of the Hog1 pathway during thermal stress as either Gcn2-dependent or Gcn2-independent and demonstrate that Hog1 activation regulates the Gcn2 pathway even in the absence of thermal stress. Finally, we implicate this phenomenon in another Hog1-regulated process, morphogenesis, and recapitulate Hog1-Gcn2 crosstalk in the distantly related fungal pathogen, . Our results point to an important link between the stress response machinery and translation control and clarify the etiology of phenotypes associated with Hog1 deletion. More broadly, this study highlights complex interplay between core conserved signal transduction pathways and the utility of molecular assays to better understand how these pathways are connected.IMPORTANCE is an opportunistic pathogen of humans that causes deadly cryptococcal meningitis, which is is responsible for an estimated 19% of AIDS-related mortality. When left untreated, cryptococcal meningitis is uniformly fatal, and in patients receiving the most effective antifungal regimens, mortality remains high. Thus, there is a critical need to identify additional targets that play a role in the adaptation to the human host and virulence. This study explores the role of the stress response kinases Hog1 and Gcn2 in thermoadaptation, which is a pre-requisite for virulence. Our results show that compensatory signaling occurs the Gcn2 pathway when Hog1 is deleted, and that disruption of both pathways increases sensitivity to thermal stress. Importantly, our study highlights the insufficiency of using single-gene deletion mutants to study gene function, since many phenotypes associated with Hog1 deletion were driven by Gcn2 signaling in this background, rather than loss of direct Hog1 activity.
该真菌是人类的一种机会性致病病原体，它会对其翻译组进行重新编程，以促进在宿主体内的适应和毒力。我们研究了Hog1/p38在热应激适应过程中对翻译重新编程的作用，发现该途径与Gcn2途径在翻译串扰中起作用，Gcn2途径是一种研究充分的一般翻译控制调节因子。通过结合分子分析和表型分析，我们表明Hog1缺失突变体中Gcn2途径输出的增加与分子和表型水平上热应激适应的挽救相关。我们将热应激期间Hog1途径的已知输出表征为Gcn2依赖性或Gcn2非依赖性，并证明即使在没有热应激的情况下，Hog1激活也能调节Gcn2途径。最后，我们将这种现象与另一个Hog1调节的过程——形态发生联系起来，并在远缘相关的真菌病原体中重现了Hog1-Gcn2串扰。我们的结果指出了应激反应机制与翻译控制之间的重要联系，并阐明了与Hog1缺失相关的表型的病因。更广泛地说，这项研究突出了核心保守信号转导途径之间的复杂相互作用以及分子分析在更好地理解这些途径如何连接方面的效用。重要性该真菌是人类的一种机会性致病病原体，可导致致命的隐球菌性脑膜炎，估计占艾滋病相关死亡率的19%。如果不进行治疗，隐球菌性脑膜炎必然致命，而在接受最有效抗真菌治疗方案的患者中，死亡率仍然很高。因此，迫切需要确定在适应人类宿主和毒力方面起作用的其他靶点。本研究探讨了应激反应激酶Hog1和Gcn2在热适应中的作用，热适应是毒力的一个先决条件。我们的结果表明，当Hog1缺失时，Gcn2途径会发生补偿性信号传导，并且两条途径的破坏都会增加对热应激的敏感性。重要的是，我们的研究强调了使用单基因缺失突变体来研究基因功能的不足，因为在这种背景下，许多与Hog1缺失相关的表型是由Gcn2信号传导驱动的，而不是直接Hog1活性的丧失。
