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Luo L, Wu X, Fan J, Dong L, Wang M, Zeng Y, Li S, Yang W, Jiang J, Wang K. FBXO7 ubiquitinates PRMT1 to suppress serine synthesis and tumor growth in hepatocellular carcinoma. Nat Commun 2024; 15:4790. [PMID: 38839752 PMCID: PMC11153525 DOI: 10.1038/s41467-024-49087-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 05/23/2024] [Indexed: 06/07/2024] Open
Abstract
Cancer cells are often addicted to serine synthesis to support growth. How serine synthesis is regulated in cancer is not well understood. We recently demonstrated protein arginine methyltransferase 1 (PRMT1) is upregulated in hepatocellular carcinoma (HCC) to methylate and activate phosphoglycerate dehydrogenase (PHGDH), thereby promoting serine synthesis. However, the mechanisms underlying PRMT1 upregulation and regulation of PRMT1-PHGDH axis remain unclear. Here, we show the E3 ubiquitin ligase F-box-only protein 7 (FBXO7) inhibits serine synthesis in HCC by binding PRMT1, inducing lysine 37 ubiquitination, and promoting proteosomal degradation of PRMT1. FBXO7-mediated PRMT1 downregulation cripples PHGDH arginine methylation and activation, resulting in impaired serine synthesis, accumulation of reactive oxygen species (ROS), and inhibition of HCC cell growth. Notably, FBXO7 is significantly downregulated in human HCC tissues, and inversely associated with PRMT1 protein and PHGDH methylation level. Overall, our study provides mechanistic insights into the regulation of cancer serine synthesis by FBXO7-PRMT1-PHGDH axis, and will facilitate the development of serine-targeting strategies for cancer therapy.
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Affiliation(s)
- Li Luo
- West China School of Basic Medical Sciences & Forensic Medicine, State Key Laboratory of Biotherapy, West China Hospital, West China School of Public Health and West China Fourth Hospital, Sichuan University, 610041, Chengdu, P. R. China
- Center for Reproductive Medicine, Department of Gynecology and Obstetrics, West China Second University Hospital, Sichuan University, 610041, Chengdu, P. R. China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, 610041, Chengdu, P. R. China
| | - Xingyun Wu
- West China School of Basic Medical Sciences & Forensic Medicine, State Key Laboratory of Biotherapy, West China Hospital, West China School of Public Health and West China Fourth Hospital, Sichuan University, 610041, Chengdu, P. R. China
| | - Jiawu Fan
- West China School of Basic Medical Sciences & Forensic Medicine, State Key Laboratory of Biotherapy, West China Hospital, West China School of Public Health and West China Fourth Hospital, Sichuan University, 610041, Chengdu, P. R. China
| | - Lixia Dong
- West China School of Basic Medical Sciences & Forensic Medicine, State Key Laboratory of Biotherapy, West China Hospital, West China School of Public Health and West China Fourth Hospital, Sichuan University, 610041, Chengdu, P. R. China
| | - Mao Wang
- West China School of Basic Medical Sciences & Forensic Medicine, State Key Laboratory of Biotherapy, West China Hospital, West China School of Public Health and West China Fourth Hospital, Sichuan University, 610041, Chengdu, P. R. China
| | - Yan Zeng
- West China School of Basic Medical Sciences & Forensic Medicine, State Key Laboratory of Biotherapy, West China Hospital, West China School of Public Health and West China Fourth Hospital, Sichuan University, 610041, Chengdu, P. R. China
| | - Sijia Li
- West China School of Basic Medical Sciences & Forensic Medicine, State Key Laboratory of Biotherapy, West China Hospital, West China School of Public Health and West China Fourth Hospital, Sichuan University, 610041, Chengdu, P. R. China
| | - Wenyong Yang
- Department of Neurosurgery, Medical Research Center, The Third People's Hospital of Chengdu, The Affiliated Hospital of Southwest Jiaotong University, The Second Chengdu Hospital Affiliated to Chongqing Medical University, 610014, Chengdu, P.R. China
| | - Jingwen Jiang
- West China School of Basic Medical Sciences & Forensic Medicine, State Key Laboratory of Biotherapy, West China Hospital, West China School of Public Health and West China Fourth Hospital, Sichuan University, 610041, Chengdu, P. R. China.
| | - Kui Wang
- West China School of Basic Medical Sciences & Forensic Medicine, State Key Laboratory of Biotherapy, West China Hospital, West China School of Public Health and West China Fourth Hospital, Sichuan University, 610041, Chengdu, P. R. China.
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Fishman-Jacob T, Youdim MBH. A sporadic Parkinson's disease model via silencing of the ubiquitin-proteasome/E3 ligase component, SKP1A. J Neural Transm (Vienna) 2024; 131:675-707. [PMID: 37644186 PMCID: PMC11192832 DOI: 10.1007/s00702-023-02687-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 08/15/2023] [Indexed: 08/31/2023]
Abstract
Our and other's laboratory microarray-derived transcriptomic studies in human PD substantia nigra pars compacta (SNpc) samples have opened an avenue to concentrate on potential gene intersections or cross-talks along the dopaminergic (DAergic) neurodegenerative cascade in sporadic PD (SPD). One emerging gene candidate identified was SKP1A (p19, S-phase kinase-associated protein 1A), found significantly decreased in the SNpc as confirmed later at the protein level. SKP1 is part of the Skp1, Cullin 1, F-box protein (SCF) complex, the largest known class of sophisticated ubiquitin-proteasome/E3-ligases and was found to directly interact with FBXO7, a gene defective in PARK15-linked PD. This finding has led us to the hypothesis that a targeted site-specific reduction of Skp1 levels in DAergic neuronal cell culture and animal systems may result in a progressive loss of DAergic neurons and hopefully recreate motor disabilities in animals. The second premise considers the possibility that both intrinsic and extrinsic factors (e.g., manipulation of selected genes and mitochondria impairing toxins), alleged to play central roles in DAergic neurodegeneration in PD, may act in concert as modifiers of Skp1 deficiency-induced phenotype alterations ('dual-hit' hypothesis of neurodegeneration). To examine a possible role of Skp1 in DAergic phenotype, we have initially knocked down the expression of SKP1A gene in an embryonic mouse SN-derived cell line (SN4741) with short hairpin RNA (shRNA) lentiviruses (LVs). The deficiency of SKP1A closely recapitulated cardinal features of the DAergic pathology of human PD, such as decreased expression of DAergic phenotypic markers and cell cycle aberrations. Furthermore, the knocked down cells displayed a lethal phenotype when induced to differentiate exhibiting proteinaceous round inclusion structures, which were almost identical in composition to human Lewy bodies, a hallmark of PD. These findings support a role for Skp1 in neuronal phenotype, survival, and differentiation. The identification of Skp1 as a key player in DAergic neuron function suggested that a targeted site-specific reduction of Skp1 levels in mice SNpc may result in a progressive loss of DAergic neurons and terminal projections in the striatum. The injected LV SKP1shRNA to mouse SN resulted in decreased expression of Skp1 protein levels within DAergic neurons and loss of tyrosine hydroxylase immunoreactivity (TH-IR) in both SNpc and striatum that was accompanied by time-dependent motor disabilities. The reduction of the vertical movements, that is rearing, may be reminiscent of the early occurrence of hypokinesia and axial, postural instability in PD. According to the 'dual-hit' hypothesis of neurodegenerative diseases, it is predicted that gene-gene and/or gene-environmental factors would act in concert or sequentially to propagate the pathological process of PD. Our findings are compatible with this conjecture showing that the genetic vulnerability caused by knock down of SKP1A renders DAergic SN4741 cells especially sensitive to genetic reduction of Aldh1 and exposure to the external stressors MPP+ and DA, which have been implicated in PD pathology. Future consideration should be given in manipulation SKP1A expression as therapeutic window, via its induction genetically or pharmacological, to prevent degeneration of the nigra striatal dopamine neurons, since UPS is defective.
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Affiliation(s)
- Tali Fishman-Jacob
- Youdim Pharmaceutical Ltd, New Northern Industrial Park, 1 Ha- Tsmikha St, Stern Building, Fl-3, P. O. Box 72, 2069207, Yokneam, Israel
| | - Moussa B H Youdim
- Youdim Pharmaceutical Ltd, New Northern Industrial Park, 1 Ha- Tsmikha St, Stern Building, Fl-3, P. O. Box 72, 2069207, Yokneam, Israel.
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Lee SH, Chung KC. USP7 attenuates endoplasmic reticulum stress-induced apoptotic cell death through deubiquitination and stabilization of FBXO7. PLoS One 2023; 18:e0290371. [PMID: 37874827 PMCID: PMC10597484 DOI: 10.1371/journal.pone.0290371] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 08/07/2023] [Indexed: 10/26/2023] Open
Abstract
Parkinson's disease (PD) is a common neurodegenerative disease (NDD) characterized by the loss of dopaminergic neurons in the substantia nigra. Similar to other NDDs, the buildup of toxic protein aggregates in PD leads to progressive neuronal loss, culminating in neurodegeneration. Accumulating evidence indicates that alterations in subcellular organelles, particularly the endoplasmic reticulum (ER), are critically involved in pathological neurodegenerative events in NDDs, including PD. Mutations in the F-box only protein 7 (FBXO7 or PARK15) gene have been found to cause early onset autosomal recessive familiar PD. FBXO7 functions as an adaptor protein in the Skp1-Cullin1-F-box protein (SCF) E3 ubiquitin ligase complex, which promotes substrate ubiquitination. Although FBXO7 is involved in the ubiquitination of various target proteins, little is known about the upstream regulatory mechanism of FBXO7 and/or its modulator(s). Ubiquitin specific protease 7 (USP7) is a deubiquitinating enzyme that regulates the balance between protein synthesis and degradation by removing ubiquitin from target substrates. The role of USP7 in various types of cancer is well-established; however, its role in NDDs has not been elucidated to date. In this study, we identified that USP7 acts as a novel regulator of FBXO7, positively regulating the stability of FBXO7 through Lys48-linked deubiquitination. Moreover, USP7 was found to mitigate ER stress-induced cytotoxicity and apoptosis by preventing the proteasomal degradation of FBXO7. Taken together, our study suggests that the functional relationship between FBXO7 and USP7 may play a crucial role in ER stress-induced apoptosis and the pathogenesis of PD.
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Affiliation(s)
- Su Hyoun Lee
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea
| | - Kwang Chul Chung
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea
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E3 ligase adaptor FBXO7 contributes to ubiquitination and proteasomal degradation of SIRT7 and promotes cell death in response to hydrogen peroxide. J Biol Chem 2023; 299:102909. [PMID: 36646384 PMCID: PMC9971319 DOI: 10.1016/j.jbc.2023.102909] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 12/28/2022] [Accepted: 01/04/2023] [Indexed: 01/15/2023] Open
Abstract
Parkinson's disease (PD) is a degenerative disorder of the central nervous system that affects 1% of the population over the age of 60. Although aging is one of the main risk factors for PD, the pathogenic mechanism of this disease remains unclear. Mutations in the F-box-only protein 7 (FBXO7) gene have been previously found to cause early onset autosomal recessive familial PD. FBXO7 is an adaptor protein in the SKP1-Cullin-1-F-box (SCF) E3 ligase complex that facilitates the ubiquitination of substrates. Sirtuin 7 (SIRT7) is an NAD+-dependent histone deacetylase that regulates aging and stress responses. In this study, we identified FBXO7 as a novel E3 ligase for SIRT7 that negatively regulates intracellular SIRT7 levels through SCF-dependent Lys-48-linked polyubiquitination and proteasomal degradation. Consequently, we show that FBXO7 promoted the blockade of SIRT7 deacetylase activity, causing an increase in acetylated histone 3 levels at the Lys-18 and Lys-36 residues and the repression of downstream RPS20 gene transcription. Moreover, we demonstrate that treatment with hydrogen peroxide triggered the FBXO7-mediated degradation of SIRT7, leading to mammalian cell death. In particular, the PD-linked FBXO7-R498X mutant, which reduced SCF-dependent E3 ligase activity, did not affect the stability of SIRT7. Collectively, these findings suggest that FBXO7 negatively regulates SIRT7 stability and may suppress the cytoprotective effects of SIRT7 during hydrogen peroxide-induced mammalian cell death.
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The characteristics of FBXO7 and its role in human diseases. Gene X 2023; 851:146972. [DOI: 10.1016/j.gene.2022.146972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 09/26/2022] [Accepted: 10/11/2022] [Indexed: 11/06/2022] Open
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Harris R, Yang M, Schmidt C, Royet C, Singh S, Natarajan A, Morris M, Frezza C, Laman H. Fbxo7 promotes Cdk6 activity to inhibit PFKP and glycolysis in T cells. J Cell Biol 2022; 221:e202203095. [PMID: 35670764 PMCID: PMC9178409 DOI: 10.1083/jcb.202203095] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 05/06/2022] [Accepted: 05/10/2022] [Indexed: 12/24/2022] Open
Abstract
Fbxo7 is associated with cancer and Parkinson's disease. Although Fbxo7 recruits substrates for SCF-type ubiquitin ligases, it also promotes Cdk6 activation in a ligase-independent fashion. We discovered PFKP, the gatekeeper of glycolysis, in a screen for Fbxo7 substrates. PFKP is an essential Cdk6 substrate in some T-ALL cells. We investigated the molecular relationship between Fbxo7, Cdk6, and PFKP, and the effect of Fbxo7 on T cell metabolism, viability, and activation. Fbxo7 promotes Cdk6-independent ubiquitination and Cdk6-dependent phosphorylation of PFKP. Importantly, Fbxo7-deficient cells have reduced Cdk6 activity, and hematopoietic and lymphocytic cells show high expression and significant dependency on Fbxo7. CD4+ T cells with reduced Fbxo7 show increased glycolysis, despite lower cell viability and activation levels. Metabolomic studies of activated CD4+ T cells confirm increased glycolytic flux in Fbxo7-deficient cells, alongside altered nucleotide biosynthesis and arginine metabolism. We show Fbxo7 expression is glucose-responsive at the mRNA and protein level and propose Fbxo7 inhibits PFKP and glycolysis via its activation of Cdk6.
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Affiliation(s)
- Rebecca Harris
- Department of Pathology, University of Cambridge, Cambridge, UK
| | - Ming Yang
- Medical Research Council Cancer Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Christina Schmidt
- Medical Research Council Cancer Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Chloe Royet
- Pôle Chimie Balard Recherche, Institut des Biomolécules Max Mousseron-UMR5247, Montpellier, France
| | - Sarbjit Singh
- Eppley Institute for Cancer Research, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE
| | - Amarnath Natarajan
- Eppley Institute for Cancer Research, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE
| | - May Morris
- Pôle Chimie Balard Recherche, Institut des Biomolécules Max Mousseron-UMR5247, Montpellier, France
| | - Christian Frezza
- Medical Research Council Cancer Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Heike Laman
- Department of Pathology, University of Cambridge, Cambridge, UK
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