“…To achieve this purpose, we expressed plasmids encoding p62 WT or the acylation-deficient mutant p62 C289,290S in WT or p62 -KO NRK cells. We found that in both cell lines, a substantial amount of the autophagy marker phosphatidylethanolamine (PE)-modified LC3 (LC3-II) 55 was accumulated upon induction of autophagy with the mTOR inhibitor Torin 1 while degradation of p62 WT was faster than that of p62 C289,290S , which was reversed by the lysosome V-ATPase inhibitor bafilomycin A1 (Baf-A1) ( Figures 3 A, 3B, and S3 A–S3D). Figure 3 S -acylation facilitates the degradation of p62 and ubiquitinated proteins (A) Immunoblot analysis of FLAG-p62 WT and FLAG-p62 C289,290S proteins in p62 -KO NRK cells.…”
“…To achieve this purpose, we expressed plasmids encoding p62 WT or the acylation-deficient mutant p62 C289,290S in WT or p62 -KO NRK cells. We found that in both cell lines, a substantial amount of the autophagy marker phosphatidylethanolamine (PE)-modified LC3 (LC3-II) 55 was accumulated upon induction of autophagy with the mTOR inhibitor Torin 1 while degradation of p62 WT was faster than that of p62 C289,290S , which was reversed by the lysosome V-ATPase inhibitor bafilomycin A1 (Baf-A1) ( Figures 3 A, 3B, and S3 A–S3D). Figure 3 S -acylation facilitates the degradation of p62 and ubiquitinated proteins (A) Immunoblot analysis of FLAG-p62 WT and FLAG-p62 C289,290S proteins in p62 -KO NRK cells.…”
“…Since the deletion of Ubp14 led to a reduction in the Gcn5 protein level, we hypothesized that autophagy may be impaired by the deletion of Ubp14. To test this hypothesis, GFP-Atg8, a commonly used autophagy pathway marker ( 45 ), was expressed in the Δ ubp14 and PH-1, and the autophagy process was determined by measuring GFP-Atg8 proteolysis ( 46 ). The breakdown of GFP-Atg8 was determined by measuring the ratio of free GFP to intact GFP-Atg8 plus free GFP.…”
The histone acetyltransferase general control non-depressible 5 (Gcn5) plays a critical role in the epigenetic landscape and chromatin modification for regulating a wide variety of biological events. However, the post-translational regulation of Gcn5 itself is poorly understood. Here, we found that Gcn5 was ubiquitinated and deubiquitinated by E3 ligase Tom1 and deubiquitinating enzyme Ubp14, respectively, in the important plant pathogenic fungus
Fusarium graminearum
. Tom1 interacted with Gcn5 in the nucleus and subsequently ubiquitinated Gcn5 mainly at K252 to accelerate protein degradation. Conversely, Ubp14 deubiquitinated Gcn5 and enhanced its stability. In the deletion mutant Δ
ubp14
, protein level of Gcn5 was significantly reduced and resulted in attenuated virulence in the fungus by affecting the mycotoxin production, autophagy process, and the penetration ability. Our findings indicate that Tom1 and Ubp14 show antagonistic functions in the control of the protein stability of Gcn5 via post-translational modification and highlight the importance of Tom1-Gcn5-Ubp14 circuit in the fungal virulence.
IMPORTANCE
Post-translational modification (PTM) enzymes have been reported to be involved in regulating numerous cellular processes. However, the modification of these PTM enzymes themselves is largely unknown. In this study, we found that the E3 ligase Tom1 and deubiquitinating enzyme Ubp14 contributed to the regulation of ubiquitination and deubiquitination of acetyltransferase Gcn5, respectively, in
Fusarium graminearum
, the causal agent of Fusarium head blight of cereals. Our findings provide deep insights into the modification of acetyltransferase Gcn5 and its dynamic regulation via ubiquitination and deubiquitination. To our knowledge, this work is the most comprehensive analysis of a regulatory network of ubiquitination that impinges on acetyltransferase in filamentous pathogens. Moreover, our findings are important because we present the novel roles of the Tom1-Gcn5-Ubp14 circuit in fungal virulence, providing novel possibilities and targets to control fungal diseases.
“…The Atg8/LC3 family of autophagy-related proteins is a component of the autophagosome membrane that functions as a bridge between cargo and autophagosomes (58). During autophagy activation, Atg8 family proteins bind to phosphatidyl ethanolamine (PE) through a lipidation process (59).…”
Mitophagy is a type of autophagy that can selectively eliminate damaged and depolarized mitochondria to maintain mitochondrial activity and cellular homeostasis. Several pathways have been found to participate in different steps of mitophagy. Mitophagy plays a significant role in the homeostasis and physiological function of vascular endothelial cells, vascular smooth muscle cells, and macrophages, and is involved in the development of atherosclerosis (AS). At present, many medications and natural chemicals have been shown to alter mitophagy and slow the progression of AS. This review serves as an introduction to the field of mitophagy for researchers interested in targeting this pathway as part of a potential AS management strategy.
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