Project description:Microsporidia are intracellular eukaryotic pathogens that pose a substantial threat to immunocompromised hosts. The way these pathogens manipulate host cells during infection remains poorly understood. Using a proximity biotinylation strategy we established that microsporidian EnP1 is a nucleus-targeted effector that modifies the host cell environment. EnP1's translocation to the host nucleus is meditated by nuclear localization signals (NLSs). In the nucleus, EnP1 interacts with host histone H2B. This interaction disrupts H2B monoubiquitination (H2Bub), subsequently impacting p53 expression. Crucially, this inhibition of p53 weakens its control over the downstream target gene SLC7A11, enhancing the host cell's resilience against ferroptosis during microsporidian infection. This favorable condition promotes the proliferation of microsporidia within the host cell. These findings shed light on the molecular mechanisms by which microsporidia modify their host cells to facilitate their survival.
Project description:The majority of fungal species prefer the 12°–30° C range and relatively few species tolerate temperatures higher than 35° C . Our understanding of the mechanisms underpinning the ability of some species to grow at higher temperatures is incomplete. Nosema ceranae is an obligate intracellular fungal parasite that infects honey bees and can cause individual mortality and contribute to colony collapse. Despite a reduced genome, this species is strikingly thermotolerant, growing optimally at the colony temperature of 35° C. In characterizing the HSR in N. ceranae, we found that this and other microsporidian species have lost the transcriptional regulator HSF and possess a reduced set of putative core HSF1-dependent HSR target genes. Despite these losses, N. ceranae demonstrates robust upregulation of the remaining HSR target genes after heat shock. In addition, thermal stress leads to alterations in genes involved in various metabolic pathways, ribosome biogenesis and translation, and DNA repair. These results provide important insight into the stress responses of microsporidia. Such new understanding will allow new comparisons with other pathogenic fungi and potentially enable discovery of novel treatment strategies for microsporidia infections affecting food production and human health.
Project description:During host cell invasion, microsporidia translocate their entire cytoplasmic contents through a thin, hollow superstructure known as the polar tube. To achieve this, the polar tube transitions from a compact spring-like state inside the environmental spore to a long needle-like tube capable of longrange sporoplasm delivery. The unique mechanical properties of the building blocks of the polar tube allow for an explosive transition from compact to extended state and support the rapid cargo translocation process. The molecular and structural factors enabling this ultrafast process and the ultrastructural changes during cargo delivery remain a mystery. Here, we employ light microscopy and in situ cryo-electron tomography to visualize multiple ultrastructural states of the polar tube, allowing us to evaluate the kinetics of its germination and characterize the underlying morphological transitions. We describe a cargo-filled state with a unique ordered arrangement of microsporidian ribosomes, which cluster along the thin tube wall, and an empty post-translocation state with a reduced diameter but a thicker wall. Together with endogenous compositional information from an affinity-purified polar tube, our work provides comprehensive novel data on the infection apparatus of microsporidia and demonstrates that ribosomes are efficiently transported through polar tubes in a spiral-like parallel arrangement.