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Wu C, Chen H, Yuan M, Zhang M, Abubakar YS, Chen X, Zhong H, Zheng W, Zheng H, Zhou J. FgAP1 σ Is Critical for Vegetative Growth, Conidiation, Virulence, and DON Biosynthesis in Fusarium graminearum. J Fungi (Basel) 2023; 9:jof9020145. [PMID: 36836259 PMCID: PMC9962196 DOI: 10.3390/jof9020145] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 01/17/2023] [Accepted: 01/19/2023] [Indexed: 01/24/2023] Open
Abstract
The AP1 complex is a highly conserved clathrin adaptor that plays important roles in regulating cargo protein sorting and intracellular vesicle trafficking in eukaryotes. However, the functions of the AP1 complex in the plant pathogenic fungi including the devastating wheat pathogen Fusarium graminearum are still unclear. In this study, we investigated the biological functions of FgAP1σ, a subunit of the AP1 complex in F. graminearum. Disruption of FgAP1σ causes seriously impaired fungal vegetative growth, conidiogenesis, sexual development, pathogenesis, and deoxynivalenol (DON) production. The ΔFgap1σ mutants were found to be less sensitive to KCl- and sorbitol-induced osmotic stresses but more sensitive to SDS-induced stress than the wild-type PH-1. Although the growth inhibition rate of the ΔFgap1σ mutants was not significantly changed under calcofluor white (CFW) and Congo red (CR) stresses, the protoplasts released from ΔFgap1σ hyphae were decreased compared with the wild-type PH-1, suggesting that FgAP1σ is necessary for cell wall integrity and osmotic stresses in F. graminearum. Subcellular localization assays showed that FgAP1σ was predominantly localized to endosomes and the Golgi apparatus. In addition, FgAP1β-GFP, FgAP1γ-GFP, and FgAP1μ-GFP also localize to the Golgi apparatus. FgAP1β interacts with FgAP1σ, FgAP1γ, and FgAP1μ, while FgAP1σ regulates the expression of FgAP1β, FgAP1γ, and FgAP1μ in F. graminearum. Furthermore, the loss of FgAP1σ blocks the transportation of the v-SNARE protein FgSnc1 from the Golgi to the plasma membrane and delays the internalization of FM4-64 dye into the vacuole. Taken together, our results demonstrate that FgAP1σ plays vital roles in vegetative growth, conidiogenesis, sexual reproduction, DON production, pathogenicity, cell wall integrity, osmotic stress, exocytosis, and endocytosis in F. graminearum. These findings unveil the functions of the AP1 complex in filamentous fungi, most notably in F. graminearum, and lay solid foundations for effective prevention and control of Fusarium head blight (FHB).
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Affiliation(s)
- Congxian Wu
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Public Technology Service Center, Fujian Medical University, Fuzhou 350122, China
| | - Huilin Chen
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Mingyue Yuan
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Meiru Zhang
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yakubu Saddeeq Abubakar
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Department of Biochemistry, Faculty of Life Sciences, Ahmadu Bello University, Zaria 810107, Nigeria
| | - Xin Chen
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Haoming Zhong
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Wenhui Zheng
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Huawei Zheng
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Institute of Oceanography, College of Geography and Oceanography, Minjiang University, Fuzhou 350108, China
- Correspondence: (H.Z.); (J.Z.)
| | - Jie Zhou
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Correspondence: (H.Z.); (J.Z.)
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Moreno MR, Boswell K, Casbolt HL, Bulgakova NA. Multifaceted control of E-cadherin dynamics by Adaptor Protein Complex 1 during epithelial morphogenesis. Mol Biol Cell 2022; 33:ar80. [PMID: 35609212 DOI: 10.1091/mbc.e21-12-0598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Intracellular trafficking regulates the distribution of transmembrane proteins including the key determinants of epithelial polarity and adhesion. The Adaptor Protein 1 (AP-1) complex is the key regulator of vesicle sorting, which binds many specific cargoes. We examined roles of the AP-1 complex in epithelial morphogenesis, using the Drosophila wing as a paradigm. We found that AP-1 knockdown leads to ectopic tissue folding, which is consistent with the observed defects in integrin targeting to the basal cell-extracellular matrix adhesion sites. This occurs concurrently with an integrin-independent induction of cell death, which counteracts elevated proliferation and prevents hyperplasia. We discovered a distinct pool of AP-1 that localizes at the subapical adherens junctions. Upon AP-1 knockdown, E-cadherin is hyperinternalized from these junctions and becomes enriched at the Golgi and recycling endosomes. We then provide evidence that E-cadherin hyperinternalization acts upstream of cell death in a potential tumor-suppressive mechanism. Simultaneously, cells compensate for elevated internalization of E-cadherin by increasing its expression to maintain cell-cell adhesion.
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Affiliation(s)
- Miguel Ramírez Moreno
- School of Biosciences and Bateson Centre, The University of Sheffield, Sheffield S10 2TN, UK
| | - Katy Boswell
- School of Biosciences and Bateson Centre, The University of Sheffield, Sheffield S10 2TN, UK
| | - Helen L Casbolt
- School of Biosciences and Bateson Centre, The University of Sheffield, Sheffield S10 2TN, UK
| | - Natalia A Bulgakova
- School of Biosciences and Bateson Centre, The University of Sheffield, Sheffield S10 2TN, UK
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Mechanisms regulating the sorting of soluble lysosomal proteins. Biosci Rep 2022; 42:231123. [PMID: 35394021 PMCID: PMC9109462 DOI: 10.1042/bsr20211856] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 04/05/2022] [Accepted: 04/07/2022] [Indexed: 11/17/2022] Open
Abstract
Lysosomes are key regulators of many fundamental cellular processes such as metabolism, autophagy, immune response, cell signalling and plasma membrane repair. These highly dynamic organelles are composed of various membrane and soluble proteins, which are essential for their proper functioning. The soluble proteins include numerous proteases, glycosidases and other hydrolases, along with activators, required for catabolism. The correct sorting of soluble lysosomal proteins is crucial to ensure the proper functioning of lysosomes and is achieved through the coordinated effort of many sorting receptors, resident ER and Golgi proteins, and several cytosolic components. Mutations in a number of proteins involved in sorting soluble proteins to lysosomes result in human disease. These can range from rare diseases such as lysosome storage disorders, to more prevalent ones, such as Alzheimer’s disease, Parkinson’s disease and others, including rare neurodegenerative diseases that affect children. In this review, we discuss the mechanisms that regulate the sorting of soluble proteins to lysosomes and highlight the effects of mutations in this pathway that cause human disease. More precisely, we will review the route taken by soluble lysosomal proteins from their translation into the ER, their maturation along the Golgi apparatus, and sorting at the trans-Golgi network. We will also highlight the effects of mutations in this pathway that cause human disease.
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Unconventional p97/VCP-Mediated Endoplasmic Reticulum-to-Endosome Trafficking of a Retroviral Protein. J Virol 2021; 95:e0053121. [PMID: 33952644 DOI: 10.1128/jvi.00531-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Mouse mammary tumor virus (MMTV) encodes a Rem precursor protein that specifies both regulatory and accessory functions. Rem is cleaved at the endoplasmic reticulum (ER) membrane into a functional N-terminal signal peptide (SP) and the C terminus (Rem-CT). Rem-CT lacks a membrane-spanning domain and a known ER retention signal, and yet it was not detectably secreted into cell supernatants. Inhibition of intracellular trafficking by the drug brefeldin A (BFA), which interferes with the ER-to-Golgi secretory pathway, resulted in dramatically reduced intracellular Rem-CT levels that were not rescued by proteasomal or lysosomal inhibitors. A Rem mutant lacking glycosylation was cleaved into SP and Rem-CT but was insensitive to BFA, suggesting that unglycosylated Rem-CT does not reach this BFA-dependent compartment. Treatment with endoglycosidase H indicated that Rem-CT does not traffic through the Golgi apparatus. Analysis of wild-type Rem-CT and its glycosylation mutant by confocal microscopy revealed that both were primarily localized to the ER lumen. A small fraction of wild-type Rem-CT, but not the unglycosylated mutant, was colocalized with Rab5-positive (Rab5+) early endosomes. The expression of a dominant-negative (DN) form of ADP ribosylation factor 1 (Arf1) (containing a mutation of threonine to asparagine at position 31 [T31N]) mimicked the effects of BFA by reducing Rem-CT levels and increased Rem-CT association with early and late endosomes. Inhibition of the AAA ATPase p97/VCP rescued Rem-CT in the presence of BFA or DN Arf1 and prevented localization to Rab5+ endosomes. Thus, Rem-CT uses an unconventional p97-mediated scheme for trafficking to early endosomes. IMPORTANCE Mouse mammary tumor virus is a complex retrovirus that encodes a regulatory/accessory protein, Rem. Rem is a precursor protein that is processed at the endoplasmic reticulum (ER) membrane by signal peptidase. The N-terminal SP uses the p97/VCP ATPase to elude ER-associated degradation to traffic to the nucleus and serve a human immunodeficiency virus Rev-like function. In contrast, the function of the C-terminal glycosylated cleavage product (Rem-CT) is unknown. Since localization is critical for protein function, we used mutants, inhibitors, and confocal microscopy to localize Rem-CT. Surprisingly, Rem-CT, which lacks a transmembrane domain or an ER retention signal, was detected primarily within the ER and required glycosylation and the p97 ATPase for early endosome trafficking without passage through the Golgi apparatus. Thus, Rem-CT uses a novel intracellular trafficking pathway, potentially impacting host antiviral immunity.
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