Biology subjects

Goich, D.

Publications and source records attributed to Goich, D..

3 recordsLinked to original sources

bioRxiv2024

Gcn2 rescues reprogramming in the absence of Hog1/p38 signaling in C. neoformans during thermal stress.

The fungus Cryptococcus neoformans is an opportunistic pathogen of people 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 via 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, Candida albicans. 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. ImportanceCryptococcus neoformans is an opportunistic pathogen of people 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 adaptation to the human host and virulence. This study explores the role of the stress response kinases Hog1 and Gcn2 in thermoadaptation, which is pre-requisite for virulence. Our results show that compensatory signaling occurs via 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.

microbiology↗

bioRxiv2022

Contributions of Ccr4 and Gcn2 to the translational response of C. neoformans to host-relevant stressors and Integrated Stress Response induction

In response to the host environment, Cryptococcus neoformans must rapidly reprogram its translatome from one which promotes growth to one which is responsive to host temperature and oxidative stress. This reprogramming is primarily driven through the Gcn2-mediated repression of translation initiation and Ccr4-mediated removal of abundant pro-growth mRNAs from the translating pool. Here we investigate the contributions of these two pathways to the translational response to stress, and show that the response to oxidative stress is primarily driven by Gcn2 whereas temperature and oxidative stress both require Ccr4. Temperature stress, but not oxidative stress, result in an increase in RNase I resistant disome. Further, eIF2 phosphorylation varies in response to the type and magnitude of stress, yet all tested conditions induce translation of integrated stress response (ISR) transcription factor Gcn4, but not necessarily the Gcn4-dependent transcription. Finally, we define the ISR regulon in response to oxidative stress in C. neoformans. Together this study identifies the differential response to host-relevant stressors in an environmental fungus which can adapt to the environment inside the human host.

molecular biology↗

bioRxiv2020

Glucan unmasking identifies regulators of temperature-induced translatome reprogramming in C. neoformans

The cell walls of fungi are critical for cellular structure and rigidity, but also serve as a major communicator to alert the cell of the changing environment. In response to stresses encountered in human hosts pathogenic fungi remodel their cell walls. Masking the b-1,3-glucan component of the cell wall is critical to escape detection by innate immune cells. We previously demonstrated that b-1,3-glucan is unmasked in response to host temperature stress when translatome reprogramming is defective in C. neoformans. Here, we used b-1,3-glucan unmasking as an output to identify signaling modules involved both in masking and translatome reprogramming in response to host temperature stress. We reveal that the High Osmolarity Glycerol (HOG) MAPK pathway is involved in translatome reprogramming and that mutants in this pathway display moderate unmasking when grown at 37{degrees}C. Additionally, we show that mutants of the Cell Wall Integrity/Mpk1 MAPK pathway extensively unmask b-1,3-glucan. While the CWI pathway does not impact translatome reprogramming, our data suggest it may play a role in the post-translational regulation of transcription factors that govern masking. ImportanceCryptococcus neoformans is a fungal pathogen that causes devastating morbidity and mortality in immunocompromised individuals. It possesses several virulence factors that aid in its evasion from the host immune system including a large polysaccharide capsule that cloaks the antigenic cell wall. Studies investigating how the cell wall is remodeled to keep this pathogen disguised in response to stress have been limited. We previously found that host temperature stress results in translatome reprogramming that is necessary for keeping the highly antigenic {beta}-(1,3)-glucan component masked. Our data reveals signaling modules that trigger these responses and suggest the points of regulations at which these pathways act in achieving masking. Understanding these mechanisms may allow for therapeutic manipulation that could promote immune recognition and clearance of this fungal pathogen.

microbiology↗