Reduced glutathione export during programmed cell death of Neurospora crassa

Abstract

In a previous study, we demonstrated that staurosporine (STS) induces programmed cell death (PCD) in the fungus Neurospora crassa and that glutathione has the capability of inhibiting both STS-induced reactive oxygen species (ROS) formation and cell death. Here, we further investigated the role of glutathione in STS-induced PCD in N. crassa and observed an efflux of reduced glutathione (GSH) together with a change in the cell internal redox state to a more oxidative environment. This event was also observed with another PCD inducer, phytosphingosine (PHS), although externally added GSH did not prevent PHS-induced PCD. The nature of ROS, detected under the experimental conditions at which GSH export occurred, is also different in the two systems, predominantly superoxide in the case of STS and hydrogen peroxide in the case of PHS. In both cases, GSH export preceded the alterations in the plasma membrane that lead to selective dye permeation. We conclude that glutathione export in the context of PCD is not exclusive of certain mammalian cells and can be extended to Fungi, being an early PCD event in N. crassa. In addition, STS and PHS induce different PCD pathways in this fungus and the role of GSH export in each of them is likely different.

Neurospora crassa transcriptomics reveals oxidative stress and plasma membrane homeostasis biology genes as key targets in response to chitosan

“…Other antifungals also induce glutathione enzymes to reduce intracellular ROS levels in N. crassa . 40 …”

CZT-1 Is a Novel Transcription Factor Controlling Cell Death and Natural Drug Resistance in Neurospora crassa

“…Staurosporine induces cell death in N. crassa accompanied by typical features like loss of viability, DNA fragmentation, ROS production, and GSH export (Castro et al 2010; Fernandes et al 2013). Previously, by screening strains from the N. crassa deletion collection (Colot et al 2006) for sensitivity to staurosporine, we observed that a strain lacking NCU09974 was highly susceptible to the drug (Fernandes et al 2011).…”

“…In N. crassa , cell death can be triggered genetically through the fusion of hyphae or germlings of two incompatible individuals at het loci (Hutchison et al 2009, 2012) or induced with phytosphingosine (Castro et al 2008; Fernandes et al 2013; Videira et al 2009), staurosporine (Castro et al 2010; Fernandes et al 2011, 2013), hydrogen peroxide (Castro et al 2008), chitosan (Palma-Guerrero et al 2009), or PAF26 (Munoz et al 2012). It can also be stimulated through ectopic expression of the phcA gene from Pseudomonas syringae (Wichmann et al 2008) or by a combined stimulus of heat shock (45°) with 2-deoxyglucose-induced glucose deprivation (Plesofsky et al 2008; Plesofsky-Vig and Brambl 1995).…”

“…It can also be stimulated through ectopic expression of the phcA gene from Pseudomonas syringae (Wichmann et al 2008) or by a combined stimulus of heat shock (45°) with 2-deoxyglucose-induced glucose deprivation (Plesofsky et al 2008; Plesofsky-Vig and Brambl 1995). In particular, we observed that staurosporine induces a cell death program that includes several cellular alterations such as loss of viability, chromatin fragmentation, early reactive oxygen species (ROS) production, and glutathione (GSH) export (Castro et al 2010; Fernandes et al 2013; Gonçalves and Videira 2014). The combined treatment with staurosporine and the classical mitochondrial complex I inhibitor rotenone (which is also an anti-mitotic agent) resulted in a synergistic inhibitory effect in the growth of Neurospora crassa , Aspergillus fumigatus , Candida albicans (Castro et al 2010), and human thyroid cancer cells (Gonçalves et al 2011a,b).…”

Functional analysis of the role of glutathione peroxidase (GPx) in the ROS signaling pathway, hyphal branching and the regulation of ganoderic acid biosynthesis in Ganoderma lucidum

“…Glutathione reductase (GR) transfers GSSG to GSH, while GPx transfers GSH to GSSG in filamentous fungi (Bai et al, 2003;Fernandes et al, 2013;Viefhues et al, 2014). Glutathione-S-transferase (GST) and thioredoxin peroxidase (TPx) augments GPx activity (Mhamdi et al, 2010).…”