Emerging role of SGT1 as a regulator of NB-LRR-receptor nucleocytoplasmic partitioning

Ryu

et al. 2017

Sci Rep

Mutations in fused in sarcoma (FUS), a DNA/RNA binding protein, are associated with familial amyotrophic lateral sclerosis (ALS). However, little is known about how ALS-causing mutations alter protein-protein and protein-RNA complexes and contribute to neurodegeneration. In this study, we identified protein arginine methyltransferase 1 (PRMT1) as a protein that more avidly associates with ALS-linked FUS-R521C than with FUS-WT (wild type) or FUS-P525L using co-immunoprecipitation and LC-MS analysis. Abnormal association between FUS-R521C and PRMT1 requires RNA, but not methyltransferase activity. PRMT1 was sequestered into cytosolic FUS-R521C-positive stress granule aggregates. Overexpression of PRMT1 rescued neurite degeneration caused by FUS-R521C upon oxidative stress, while loss of PRMT1 further accumulated FUS-positive aggregates and enhanced neurite degeneration. Furthermore, the mRNA of Nd1-L, an actin-stabilizing protein, was sequestered into the FUS-R521C/PRMT1 complex. Nd1-L overexpression rescued neurite shortening caused by FUS-R521C upon oxidative stress, while loss of Nd1-L further exacerbated neurite shortening. Altogether, these data suggest that the abnormal stable complex of FUS-R521C/PRMT1/Nd1-L mRNA could contribute to neurodegeneration upon oxidative stress. Overall, our study provides a novel pathogenic mechanism of the FUS mutation associated with abnormal protein-RNA complexes upon oxidative stress in ALS and provides insight into possible therapeutic targets for this pathology.

Section: Methodsmentioning

confidence: 99%

Sequestration of PRMT1 and Nd1-L mRNA into ALS-linked FUS mutant R521C-positive aggregates contributes to neurite degeneration upon oxidative stress

Ryu

et al. 2017

Sci Rep

“…The Rx protein also associates with the molecular chaperone HSP90 and its signaling proteins SGT1 and RAR1 to modulate the innate immune response in plants (Botër et al, 2007). The cochaperone SGT1 also interferes with the nucleocytoplasmic distribution of Rx protein (Slootweg et al, 2010; Hoser et al, 2014). Accordingly, silencing the cochaperone SGT1 impaired the accumulation of Rx1 protein in the nucleus and Rx distribution exactly mirrored that of ectopic AtSGT1b variants with forced cytoplasmic or nuclear localization.…”

Section: Effector-triggered Immunity In Antiviral Defense: R Gene-medmentioning

confidence: 99%

Immune Receptors and Co-receptors in Antiviral Innate Immunity in Plants

et al. 2017

Plants respond to pathogens using an innate immune system that is broadly divided into PTI (pathogen-associated molecular pattern- or PAMP-triggered immunity) and ETI (effector-triggered immunity). PTI is activated upon perception of PAMPs, conserved motifs derived from pathogens, by surface membrane-anchored pattern recognition receptors (PRRs). To overcome this first line of defense, pathogens release into plant cells effectors that inhibit PTI and activate effector-triggered susceptibility (ETS). Counteracting this virulence strategy, plant cells synthesize intracellular resistance (R) proteins, which specifically recognize pathogen effectors or avirulence (Avr) factors and activate ETI. These coevolving pathogen virulence strategies and plant resistance mechanisms illustrate evolutionary arms race between pathogen and host, which is integrated into the zigzag model of plant innate immunity. Although antiviral immune concepts have been initially excluded from the zigzag model, recent studies have provided several lines of evidence substantiating the notion that plants deploy the innate immune system to fight viruses in a manner similar to that used for non-viral pathogens. First, most R proteins against viruses so far characterized share structural similarity with antibacterial and antifungal R gene products and elicit typical ETI-based immune responses. Second, virus-derived PAMPs may activate PTI-like responses through immune co-receptors of plant PTI. Finally, and even more compelling, a viral Avr factor that triggers ETI in resistant genotypes has recently been shown to act as a suppressor of PTI, integrating plant viruses into the co-evolutionary model of host-pathogen interactions, the zigzag model. In this review, we summarize these important progresses, focusing on the potential significance of antiviral immune receptors and co-receptors in plant antiviral innate immunity. In light of the innate immune system, we also discuss a newly uncovered layer of antiviral defense that is specific to plant DNA viruses and relies on transmembrane receptor-mediated translational suppression for defense.

“…Our analysis of TaSGT1 localization in planta by transiently expressing GFP-SGT1 in N. benthamiana supports this conclusion. It is clear that SGT1 shuttles between the nucleus and the cytoplasm, which may contribute to the trafficking of some genes, such as Nod1 (Correia et al, 2007), N (Hoser et al, 2013) and Rx (Hoser et al, 2014). PstSIE1 is localized in the plant cytoplasm and nucleus (Figure S6).…”

Section: Discussionmentioning

confidence: 99%

A stripe rust fungal effector PstSIE1 targets TaSGT1 to facilitate pathogen infection

Wang

Liu

et al. 2022

The Plant Journal

SUMMARY Puccinia striiformis f. sp. tritici (Pst), the causal agent of stripe rust, is a destructive pathogen of Triticum aestivum (wheat), threatening wheat production worldwide. Pst delivers hundreds of effectors to manipulate processes in its hosts during infection. The SGT1 (suppressor of the G2 allele of skp1), RAR1 (required for Mla12 resistance) and HSP90 (heat‐shock protein 90) proteins form a chaperone complex that acts as a core modulator in plant immunity. However, little is known about how Pst effectors target this immune component to suppress plant immunity. Here, we identified a Pst effector PstSIE1 that interacts with TaSGT1 in wheat and is upregulated during the early infection stage. Transient expression of PstSIE1 suppressed cell death in Nicotiana benthamiana induced by VmE02 and PcNLP2. Transgenic expression of PstSIE1‐RNAi constructs in wheat significantly reduced the virulence of Pst. Overexpression of PstSIE1 in wheat increased the number of rust pustules and reduced the accumulation of reactive oxygen species (ROS), indicating that PstSIE1 functions as an important pathogenicity factor in Pst. PstSIE1 was found to compete with TaRAR1 to bind TaSGT1, thus disrupting the formation of the TaRAR1–TaSGT1 subcomplex. Taken together, PstSIE1 is an important Pst effector targeting the immune component TaSGT1 and involved in suppressing wheat defense.