Studies on the involvement of the NPF protein in the adaptive responses of Neurospora crassa to oxidative stress and pH alterations

• Grant number: 24/06737-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2024
• End date: October 31, 2025
• Field of knowledge: Biological Sciences - Microbiology - Biology and Physiology of Microorganisms
• Principal Investigator: Fernanda Zanolli Freitas
• Grantee: Maria Eduarda Ferraz Espindola
• Host Institution: Instituto de Química (IQ). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil

Abstract

All living cells respond and adapt to environmental conditions in different ways. For this to occur, a series of cellular events must happen in an orchestrated manner, involving the production, activation, or repression of many cellular proteins, to modulate specific intracellular signaling pathways. These events are only possible due to intense control of gene expression, which in eukaryotes results from the combination of transcription factors associating with regulatory DNA sequences into the genomes and chromatin remodeling events. One stressing condition frequently faced by cells are the ambient temperature changes. In this context, several studies addressing cellular responses of microorganisms during heat shock have been conducted in our research group. Previous results have shown that in N. crassa, the temperature increase (30 to 45°C) can positively or negatively regulate gene expression, depending on the presence of Stress Response Elements (STRE) in the promoters of stress-responsive genes. During the identification of the Neurospora transcription factor that binds the STRE element during heat shock, we identified several interesting nuclear proteins with yet unknown functions, including NPF - an ortholog of Drosophila's NURF55 and human's RBAP46/48, a component of the Polycomb Repressive Complex 2 (PRC2). In N. crassa, the four core components of PRC2 (SET-7, EED, SUZ12, and NPF) were found to be conserved, and in the fungus, PRC2 trimethylates the Lys27 residue of histone H3 (H3K27me3), promoting chromatin compaction and transcriptional silencing. However, much remains unknown about PRC2 and the gene expression control mechanism in filamentous fungi, as well as the importance of NPF in this complex during fungal adaptive response to stressful events, which requires further investigation. Since NPF was identified during heat stress while searching for the SEB-1 transcription factor, responsible for gene expression repression under this condition via STRE, it is possible that NPF contributes to gene repression during heat stress, and possibly, the seb-1 and npf genes are components of the stress regulatory center (CSR) that governs the N. crassa cellular adaptive response to certain environmental conditions. In this work, we specifically aim to study the involvement of NPF in the Neurospora cellular adaptive response to oxidative stress and pH environmental changes. As this proposal is part of a larger project in our group, the results obtained here will allow us to relate chromatin remodeling events and gene transcription in a STRE-dependent manner, and thereby understand in part how filamentous fungi adapt to different environmental conditions through gene expression modulation.