1
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Coates HW, Nguyen TB, Du X, Olzomer EM, Farrell R, Byrne FL, Yang H, Brown AJ. The constitutively active form of a key cholesterol synthesis enzyme is lipid droplet-localized and upregulated in endometrial cancer tissues. J Biol Chem 2024; 300:107232. [PMID: 38537696 PMCID: PMC11061744 DOI: 10.1016/j.jbc.2024.107232] [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: 02/29/2024] [Accepted: 03/18/2024] [Indexed: 04/26/2024] Open
Abstract
Cholesterol is essential for both normal cell viability and cancer cell proliferation. Aberrant activity of squalene monooxygenase (SM, also known as squalene epoxidase), the rate-limiting enzyme of the committed cholesterol synthesis pathway, is accordingly implicated in a growing list of cancers. We previously reported that hypoxia triggers the truncation of SM to a constitutively active form, thus preserving sterol synthesis during oxygen shortfalls. Here, we show SM truncation is upregulated and correlates with the magnitude of hypoxia in endometrial cancer tissues, supporting the in vivo relevance of our earlier work. To further investigate the pathophysiological consequences of SM truncation, we examined its lipid droplet-localized pool using complementary immunofluorescence and cell fractionation approaches and found that it exclusively comprises the truncated enzyme. This partitioning is facilitated by the loss of an endoplasmic reticulum-embedded region at the SM N terminus, whereas the catalytic domain containing membrane-associated C-terminal helices is spared. Moreover, we determined multiple amphipathic helices contribute to the lipid droplet localization of truncated SM. Taken together, our results expand on the striking differences between the two forms of SM and suggest upregulated truncation may contribute to SM-related oncogenesis.
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Affiliation(s)
- Hudson W Coates
- School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, New South Wales, Australia
| | - Tina B Nguyen
- School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, New South Wales, Australia
| | - Ximing Du
- School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, New South Wales, Australia
| | - Ellen M Olzomer
- School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, New South Wales, Australia
| | - Rhonda Farrell
- Chris O'Brien Lifehouse, Camperdown, New South Wales, Australia; Prince of Wales Private Hospital, Randwick, New South Wales, Australia
| | - Frances L Byrne
- School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, New South Wales, Australia
| | - Hongyuan Yang
- School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, New South Wales, Australia
| | - Andrew J Brown
- School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, New South Wales, Australia.
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2
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Zhang L, Cao Z, Hong Y, He H, Chen L, Yu Z, Gao Y. Squalene Epoxidase: Its Regulations and Links with Cancers. Int J Mol Sci 2024; 25:3874. [PMID: 38612682 PMCID: PMC11011400 DOI: 10.3390/ijms25073874] [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: 01/09/2024] [Revised: 03/09/2024] [Accepted: 03/19/2024] [Indexed: 04/14/2024] Open
Abstract
Squalene epoxidase (SQLE) is a key enzyme in the mevalonate-cholesterol pathway that plays a critical role in cellular physiological processes. It converts squalene to 2,3-epoxysqualene and catalyzes the first oxygenation step in the pathway. Recently, intensive efforts have been made to extend the current knowledge of SQLE in cancers through functional and mechanistic studies. However, the underlying mechanisms and the role of SQLE in cancers have not been fully elucidated yet. In this review, we retrospected current knowledge of SQLE as a rate-limiting enzyme in the mevalonate-cholesterol pathway, while shedding light on its potential as a diagnostic and prognostic marker, and revealed its therapeutic values in cancers. We showed that SQLE is regulated at different levels and is involved in the crosstalk with iron-dependent cell death. Particularly, we systemically reviewed the research findings on the role of SQLE in different cancers. Finally, we discussed the therapeutic implications of SQLE inhibitors and summarized their potential clinical values. Overall, this review discussed the multifaceted mechanisms that involve SQLE to present a vivid panorama of SQLE in cancers.
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Affiliation(s)
- Lin Zhang
- Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen 518116, China
| | - Zheng Cao
- Department of Pathology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
| | - Yuheng Hong
- Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
| | - Haihua He
- Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
- Department of Oncology, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Leifeng Chen
- Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
- Department of Oncology, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Zhentao Yu
- Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen 518116, China
| | - Yibo Gao
- Central Laboratory & Shenzhen Key Laboratory of Epigenetics and Precision Medicine for Cancers, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen 518116, China
- State Key Laboratory of Molecular Oncology, National Cancer Center, National Clinical Research Center for Cancer, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
- Laboratory of Translational Medicine, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
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3
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Shao M, Wang M, Wang X, Feng X, Zhang L, Lv H. SQLE is a promising prognostic and immunological biomarker and correlated with immune Infiltration in Sarcoma. Medicine (Baltimore) 2024; 103:e37030. [PMID: 38335381 PMCID: PMC10861000 DOI: 10.1097/md.0000000000037030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Revised: 11/24/2023] [Accepted: 01/02/2024] [Indexed: 02/12/2024] Open
Abstract
Squalene epoxidase (SQLE) is an essential enzyme involved in cholesterol biosynthesis. However, its role in sarcoma and its correlation with immune infiltration remains unclear. All original data were downloaded from The Cancer Genome Atlas (TCGA). SQLE expression was explored using the TCGA database, and correlations between SQLE and cancer immune characteristics were analyzed via the TISIDB databases. Generally, SQLE is predominantly overexpressed and has diagnostic and prognostic value in sarcoma. Upregulated SQLE was associated with poorer overall survival, poorer disease-specific survival, and tumor multifocality in sarcoma. Mechanistically, we identified a hub gene that included a total of 82 SQLE-related genes, which were tightly associated with histone modification pathways in sarcoma patients. SQLE expression was negatively correlated with infiltrating levels of dendritic cells and plasmacytoid dendritic cells and positively correlated with Th2 cells. SQLE expression was negatively correlated with the expression of chemokines (CCL19 and CX3CL1) and chemokine receptors (CCR2 and CCR7) in sarcoma. In conclusion, SQLE may be used as a prognostic biomarker for determining prognosis and immune infiltration in sarcoma.
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Affiliation(s)
- Mengwei Shao
- Department of Orthopedics, The Second Affiliated Hospital of Inner Mongolia Medical University, Hohhot, China
| | - Mingbo Wang
- Department of Orthopedics, The Second Affiliated Hospital of Inner Mongolia Medical University, Hohhot, China
| | - Xiliang Wang
- Department of Orthopedics, The Second Affiliated Hospital of Inner Mongolia Medical University, Hohhot, China
| | - Xiaodong Feng
- Department of Orthopedics, The Second Affiliated Hospital of Inner Mongolia Medical University, Hohhot, China
| | - Lifeng Zhang
- Department of Orthopedics, The Second Affiliated Hospital of Inner Mongolia Medical University, Hohhot, China
| | - Huicheng Lv
- Department of Orthopedics, The Second Affiliated Hospital of Inner Mongolia Medical University, Hohhot, China
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4
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Avci D, Heidasch R, Costa M, Lüchtenborg C, Kale D, Brügger B, Lemberg MK. Intramembrane protease SPP defines a cholesterol-regulated abundance control of the mevalonate pathway enzyme squalene synthase. J Biol Chem 2024; 300:105644. [PMID: 38218226 PMCID: PMC10850959 DOI: 10.1016/j.jbc.2024.105644] [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: 05/24/2023] [Revised: 12/21/2023] [Accepted: 01/02/2024] [Indexed: 01/15/2024] Open
Abstract
Intramembrane proteolysis regulates important processes such as signaling and transcriptional and posttranslational abundance control of proteins with key functions in metabolic pathways. This includes transcriptional control of mevalonate pathway genes, thereby ensuring balanced biosynthesis of cholesterol and other isoprenoids. Our work shows that, at high cholesterol levels, signal peptide peptidase (SPP) cleaves squalene synthase (SQS), an enzyme that defines the branching point for allocation of isoprenoids to the sterol and nonsterol arms of the mevalonate pathway. This intramembrane cleavage releases SQS from the membrane and targets it for proteasomal degradation. Regulation of this mechanism is achieved by the E3 ubiquitin ligase TRC8 that, in addition to ubiquitinating SQS in response to cholesterol levels, acts as an allosteric activator of SPP-catalyzed intramembrane cleavage of SQS. Cellular cholesterol levels increase in the absence of SPP activity. We infer from these results that, SPP-TRC8 mediated abundance control of SQS acts as a regulation step within the mevalonate pathway.
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Affiliation(s)
- Dönem Avci
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany; Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany.
| | - Ronny Heidasch
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Martina Costa
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany; Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany
| | | | - Dipali Kale
- Biochemistry Center of Heidelberg University (BZH), Heidelberg, Germany
| | - Britta Brügger
- Biochemistry Center of Heidelberg University (BZH), Heidelberg, Germany
| | - Marius K Lemberg
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany; Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany.
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5
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Mehta A, Ratre YK, Soni VK, Shukla D, Sonkar SC, Kumar A, Vishvakarma NK. Orchestral role of lipid metabolic reprogramming in T-cell malignancy. Front Oncol 2023; 13:1122789. [PMID: 37256177 PMCID: PMC10226149 DOI: 10.3389/fonc.2023.1122789] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 04/12/2023] [Indexed: 06/01/2023] Open
Abstract
The immune function of normal T cells partially depends on the maneuvering of lipid metabolism through various stages and subsets. Interestingly, T-cell malignancies also reprogram their lipid metabolism to fulfill bioenergetic demand for rapid division. The rewiring of lipid metabolism in T-cell malignancies not only provides survival benefits but also contributes to their stemness, invasion, metastasis, and angiogenesis. Owing to distinctive lipid metabolic programming in T-cell cancer, quantitative, qualitative, and spatial enrichment of specific lipid molecules occur. The formation of lipid rafts rich in cholesterol confers physical strength and sustains survival signals. The accumulation of lipids through de novo synthesis and uptake of free lipids contribute to the bioenergetic reserve required for robust demand during migration and metastasis. Lipid storage in cells leads to the formation of specialized structures known as lipid droplets. The inimitable changes in fatty acid synthesis (FAS) and fatty acid oxidation (FAO) are in dynamic balance in T-cell malignancies. FAO fuels the molecular pumps causing chemoresistance, while FAS offers structural and signaling lipids for rapid division. Lipid metabolism in T-cell cancer provides molecules having immunosuppressive abilities. Moreover, the distinctive composition of membrane lipids has implications for immune evasion by malignant cells of T-cell origin. Lipid droplets and lipid rafts are contributors to maintaining hallmarks of cancer in malignancies of T cells. In preclinical settings, molecular targeting of lipid metabolism in T-cell cancer potentiates the antitumor immunity and chemotherapeutic response. Thus, the direct and adjunct benefit of lipid metabolic targeting is expected to improve the clinical management of T-cell malignancies.
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Affiliation(s)
- Arundhati Mehta
- Department of Biotechnology, Guru Ghasidas Vishwavidyalaya, Bilaspur, Chhattisgarh, India
| | - Yashwant Kumar Ratre
- Department of Biotechnology, Guru Ghasidas Vishwavidyalaya, Bilaspur, Chhattisgarh, India
| | | | - Dhananjay Shukla
- Department of Biotechnology, Guru Ghasidas Vishwavidyalaya, Bilaspur, Chhattisgarh, India
| | - Subhash C. Sonkar
- Multidisciplinary Research Unit, Maulana Azad Medical College, University of Delhi, New Delhi, India
| | - Ajay Kumar
- Department of Zoology, Banaras Hindu University, Varanasi, India
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6
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Ganji R, Paulo JA, Xi Y, Kline I, Zhu J, Clemen CS, Weihl CC, Purdy JG, Gygi SP, Raman M. The p97-UBXD8 complex regulates ER-Mitochondria contact sites by altering membrane lipid saturation and composition. Nat Commun 2023; 14:638. [PMID: 36746962 PMCID: PMC9902492 DOI: 10.1038/s41467-023-36298-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 01/25/2023] [Indexed: 02/08/2023] Open
Abstract
The intimate association between the endoplasmic reticulum (ER) and mitochondrial membranes at ER-Mitochondria contact sites (ERMCS) is a platform for critical cellular processes, particularly lipid synthesis. How contacts are remodeled and the impact of altered contacts on lipid metabolism remains poorly understood. We show that the p97 AAA-ATPase and its adaptor ubiquitin-X domain adaptor 8 (UBXD8) regulate ERMCS. The p97-UBXD8 complex localizes to contacts and its loss increases contacts in a manner that is dependent on p97 catalytic activity. Quantitative proteomics and lipidomics of ERMCS demonstrates alterations in proteins regulating lipid metabolism and a significant change in membrane lipid saturation upon UBXD8 deletion. Loss of p97-UBXD8 increased membrane lipid saturation via SREBP1 and the lipid desaturase SCD1. Aberrant contacts can be rescued by unsaturated fatty acids or overexpression of SCD1. We find that the SREBP1-SCD1 pathway is negatively impacted in the brains of mice with p97 mutations that cause neurodegeneration. We propose that contacts are exquisitely sensitive to alterations to membrane lipid composition and saturation.
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Affiliation(s)
- Rakesh Ganji
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, USA
| | - Joao A Paulo
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Yuecheng Xi
- Department of Immunobiology, BIO5 Institute, University of Arizona College of Medicine, Tucson, AZ, USA
| | - Ian Kline
- Department of Immunobiology, BIO5 Institute, University of Arizona College of Medicine, Tucson, AZ, USA
| | - Jiang Zhu
- Department of Neurology, Washington University School of Medicine, Saint Louis, MO, USA
- Ilumina Inc., San Diego, CA, USA
| | - Christoph S Clemen
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
- Center for Physiology and Pathophysiology, Institute of Vegetative Physiology, Medical Faculty, University of Cologne, Cologne, Germany
| | - Conrad C Weihl
- Department of Neurology, Washington University School of Medicine, Saint Louis, MO, USA
| | - John G Purdy
- Department of Immunobiology, BIO5 Institute, University of Arizona College of Medicine, Tucson, AZ, USA
| | - Steve P Gygi
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Malavika Raman
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, USA.
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7
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Coates HW, Capell-Hattam IM, Olzomer EM, Du X, Farrell R, Yang H, Byrne FL, Brown AJ. Hypoxia truncates and constitutively activates the key cholesterol synthesis enzyme squalene monooxygenase. eLife 2023; 12:82843. [PMID: 36655986 PMCID: PMC9851614 DOI: 10.7554/elife.82843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 12/13/2022] [Indexed: 01/20/2023] Open
Abstract
Cholesterol synthesis is both energy- and oxygen-intensive, yet relatively little is known of the regulatory effects of hypoxia on pathway enzymes. We previously showed that the rate-limiting and first oxygen-dependent enzyme of the committed cholesterol synthesis pathway, squalene monooxygenase (SM), can undergo partial proteasomal degradation that renders it constitutively active. Here, we show hypoxia is a physiological trigger for this truncation, which occurs through a two-part mechanism: (1) increased targeting of SM to the proteasome via stabilization of the E3 ubiquitin ligase MARCHF6 and (2) accumulation of the SM substrate, squalene, which impedes the complete degradation of SM and liberates its truncated form. This preserves SM activity and downstream pathway flux during hypoxia. These results uncover a feedforward mechanism that allows SM to accommodate fluctuating substrate levels and may contribute to its widely reported oncogenic properties.
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Affiliation(s)
- Hudson W Coates
- School of Biotechnology and Biomolecular Sciences, UNSW SydneySydneyAustralia
| | | | - Ellen M Olzomer
- School of Biotechnology and Biomolecular Sciences, UNSW SydneySydneyAustralia
| | - Ximing Du
- School of Biotechnology and Biomolecular Sciences, UNSW SydneySydneyAustralia
| | - Rhonda Farrell
- Prince of Wales Private HospitalRandwickAustralia
- Chris O’Brien LifehouseCamperdownAustralia
| | - Hongyuan Yang
- School of Biotechnology and Biomolecular Sciences, UNSW SydneySydneyAustralia
| | - Frances L Byrne
- School of Biotechnology and Biomolecular Sciences, UNSW SydneySydneyAustralia
| | - Andrew J Brown
- School of Biotechnology and Biomolecular Sciences, UNSW SydneySydneyAustralia
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8
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Kawamura K, Yoshioka H, Sato C, Yajima T, Furuyama Y, Kuramochi K, Ohgane K. Fine-tuning of nitrogen-containing bisphosphonate esters that potently induce degradation of HMG-CoA reductase. Bioorg Med Chem 2023; 78:117145. [PMID: 36580745 DOI: 10.1016/j.bmc.2022.117145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 12/20/2022] [Accepted: 12/20/2022] [Indexed: 12/25/2022]
Abstract
3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase is the rate-limiting enzyme in the cholesterol biosynthetic pathway, and competitive inhibitors targeting the catalytic domain of this enzyme, so-called statins, are widely used for the treatment of hyperlipidemia. The membrane domain mediates the sterol-accelerated degradation, a post-translational negative feedback mechanism, and small molecules triggering such degradation have been studied as an alternative therapeutic option. Such strategies are expected to provide benefits over catalytic site inhibitors, as the inhibition leads to transcriptional and post-translational upregulation of the enzyme, necessitating a higher dose of the inhibitors and concomitantly increasing the risk of serious adverse effects, including myopathies. Through our previous study on SR12813, a synthetic small molecule that induces degradation of HMG-CoA reductase, we identified a nitrogen-containing bisphosphonate ester SRP3042 as a highly potent HMG-CoA reductase degrader. Here, we performed a systematic structure-activity relationship study to optimize its activity and physicochemical properties, specifically focusing on the reduction of lipophilicity. Mono-fluorination of tert-butyl groups on the molecules was found to increase the HMG-CoA reductase degradation activity while reducing lipophilicity, suggesting the mono-fluorination of saturated alkyl groups as a useful strategy to balance potency and lipophilicity of the lead compounds.
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Affiliation(s)
- Kota Kawamura
- Department of Applied Bioscience, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8519, Japan
| | - Hiromasa Yoshioka
- Institute for Quantitative Biosciences, The University of Tokyo, 1-1 Yayoi, Bunkyo, Tokyo 13-0032, Japan
| | - Chikako Sato
- Department of Chemistry, Ochanomizu University, 2-1-1 Otsuka, Bunkyo, Tokyo 112-8610, Japan
| | - Tomoko Yajima
- Department of Chemistry, Ochanomizu University, 2-1-1 Otsuka, Bunkyo, Tokyo 112-8610, Japan
| | - Yuuki Furuyama
- Department of Applied Bioscience, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8519, Japan
| | - Kouji Kuramochi
- Department of Applied Bioscience, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8519, Japan
| | - Kenji Ohgane
- Department of Applied Bioscience, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8519, Japan; Department of Chemistry, Ochanomizu University, 2-1-1 Otsuka, Bunkyo, Tokyo 112-8610, Japan.
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9
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Zhang Z, Wu W, Jiao H, Chen Y, Ji X, Cao J, Yin F, Yin W. Squalene epoxidase promotes hepatocellular carcinoma development by activating STRAP transcription and TGF-β/SMAD signalling. Br J Pharmacol 2022; 180:1562-1581. [PMID: 36581319 DOI: 10.1111/bph.16024] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 08/20/2022] [Accepted: 09/11/2022] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND AND PURPOSE Squalene epoxidase (SQLE) is a key enzyme involved in cholesterol biosynthesis, but growing evidence also reveals that SQLE is abnormally expressed in some types of malignant tumours, even though the underlying mechanism remains poorly understood. EXPERIMENTAL APPROACH Bioinformatics analysis and RNA sequencing were applied to detect differentially expressed genes in clinical hepatocellular carcinoma (HCC). MTT, colony formation, AnnexinV-FITC/PI, EdU, wound healing, transwell, western blot, qRT-PCR, IHC, F-actin, RNA-sequencing, dual-luciferase reporters, and H&E staining were used to investigate the pharmacological effects and possible mechanisms of SQLE. KEY RESULTS SQLE expression was specifically elevated in HCC, correlating with poor clinical outcomes. SQLE significantly promoted HCC growth, epithelial-mesenchymal transition, and metastasis both in vitro and in vivo. RNA sequencing and functional experiments revealed that the protumourigenic effect of SQLE on HCC was closely related to the activation of TGF-β/SMAD signalling, but the stimulatory effect of SQLE on TGF-β/SMAD signalling and HCC development is critically dependent on STRAP. SQLE expression is well correlated with STRAP in HCC, and further, to amplify TGF-β/SMAD signalling, SQLE even transcriptionally increased STRAP gene expression mediated by AP-2α. Finally, as a chemical inhibitor of SQLE, NB-598 markedly inhibited HCC cell growth and tumour development. CONCLUSIONS AND IMPLICATIONS Taken together, SQLE serves as a novel oncogene in HCC development by activating TGF-β/SMAD signalling. Targeting SQLE could be useful in drug development and therapy for HCC.
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Affiliation(s)
- Zhirui Zhang
- The State Key Lab of Pharmaceutical Biotechnology, College of Life Sciences, Nanjing University, Nanjing, China
| | - Wei Wu
- Organ Transplantation Center, Southern District, the First Affiliated Hospital of University of Science and Technology of China (Anhui Provincial Hospital), Hefei, China
| | - Hao Jiao
- Department of Pharmacy, Fuyang People's Hospital, Fuyang, China
| | - Yuzhong Chen
- Department of Surgical Oncology, First Affiliated Hospital of Bengbu Medical College, Bengbu, China
| | - Xiaojun Ji
- Department of Innovation, Nanjing Chia Tai Tianqing Pharmaceutical Co., Ltd, Nanjing, China
| | - Jing Cao
- Department of Pharmacy, Women's Hospital of Nanjing Medical University/Nanjing Maternity and Child Health Care Hospital, Nanjing, China
| | - Fangzhou Yin
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, China
| | - Wu Yin
- The State Key Lab of Pharmaceutical Biotechnology, College of Life Sciences, Nanjing University, Nanjing, China
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10
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Huertas-Abril PV, Prieto-Álamo MJ, Jurado J, García-Barrera T, Abril N. A selenium-enriched diet helps to recover liver function after antibiotic administration in mice. Food Chem Toxicol 2022; 171:113519. [PMID: 36464106 DOI: 10.1016/j.fct.2022.113519] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 10/20/2022] [Accepted: 11/18/2022] [Indexed: 12/05/2022]
Abstract
Antibiotic (Abx) treatments or inadvertent exposure to Abx-contaminated food and water can adversely affect health. Many studies show strong correlations between Abx and liver damage pointing to gut dysbiosis as a contributing factor because the gut microbiota (GM) forms a complex network with liver. Selenium (Se) is a beneficial micronutrient able to shape the composition of the GM. We analyzed here the ability of a low dose (120 μg/kg bodyweight/day) Se-enriched diet to ameliorate the effects of a 7-day intervention with an Abx-cocktail over the global health and the homeostasis of cholesterol and bile acids in the mouse liver. We found that Se restored lipid metabolism preventing the increased synthesis and accumulation of cholesterol caused by Abx treatment. Integrating these results with previous metataxonomic and metabolomic data in same mice, we conclude that part of the effect of Se against liver dysfunction (cholesterol and bile acids metabolism and transport) could be mediated by the GM. We provide data that contribute to a more complete view of the molecular mechanisms underlying the beneficial action of Se on health, pointing to a possible use of low doses of Se as a functional food additive (prebiotic) to prevent the negative effects of antibiotics.
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Affiliation(s)
- Paula V Huertas-Abril
- Department of Biochemistry and Molecular Biology, University of Córdoba, Campus de Rabanales, Edificio Severo Ochoa, E-14071, Córdoba, Spain
| | - María-José Prieto-Álamo
- Department of Biochemistry and Molecular Biology, University of Córdoba, Campus de Rabanales, Edificio Severo Ochoa, E-14071, Córdoba, Spain.
| | - Juan Jurado
- Department of Biochemistry and Molecular Biology, University of Córdoba, Campus de Rabanales, Edificio Severo Ochoa, E-14071, Córdoba, Spain
| | - Tamara García-Barrera
- Research Center of Natural Resources, Health and the Environment (RENSMA). Department of Chemistry, Faculty of Experimental Sciences, Campus El Carmen, University of Huelva, Fuerzas Armadas Ave., 21007, Huelva, Spain
| | - Nieves Abril
- Department of Biochemistry and Molecular Biology, University of Córdoba, Campus de Rabanales, Edificio Severo Ochoa, E-14071, Córdoba, Spain.
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11
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Huang LJ, Chen RH. Lipid saturation induces degradation of squalene epoxidase for sterol homeostasis and cell survival. Life Sci Alliance 2022; 6:6/1/e202201612. [PMID: 36368908 PMCID: PMC9652772 DOI: 10.26508/lsa.202201612] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 10/24/2022] [Accepted: 10/25/2022] [Indexed: 11/13/2022] Open
Abstract
A fluid membrane containing a mix of unsaturated and saturated lipids is essential for life. However, it is unclear how lipid saturation might affect lipid homeostasis, membrane-associated proteins, and membrane organelles. Here, we generate temperature-sensitive mutants of the sole fatty acid desaturase gene OLE1 in the budding yeast Saccharomyces cerevisiae Using these mutants, we show that lipid saturation triggers the endoplasmic reticulum-associated degradation (ERAD) of squalene epoxidase Erg1, a rate-limiting enzyme in sterol biosynthesis, via the E3 ligase Doa10-Ubc7 complex. We identify the P469L mutation that abolishes the lipid saturation-induced ERAD of Erg1. Overexpressed WT or stable Erg1 mutants all mislocalize into foci in the ole1 mutant, whereas the stable Erg1 causes aberrant ER and severely compromises the growth of ole1, which are recapitulated by doa10 deletion. The toxicity of the stable Erg1 and doa10 deletion is due to the accumulation of lanosterol and misfolded proteins in ole1 Our study identifies Erg1 as a novel lipid saturation-regulated ERAD target, manifesting a close link between lipid homeostasis and proteostasis that maintains sterol homeostasis under the lipid saturation condition for cell survival.
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Affiliation(s)
| | - Rey-Huei Chen
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
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Krøyer Rasmussen M, Thøgersen R, Horsbøl Lindholm P, Bertram HC, Pilegaard H. Hepatic PGC-1α has minor regulatory effect on the transcriptome and metabolome during high fat high fructose diet and exercise. Gene 2022; 851:147039. [DOI: 10.1016/j.gene.2022.147039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 10/31/2022] [Accepted: 11/04/2022] [Indexed: 11/10/2022]
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The Non Catalytic Protein ERG28 has a Functional Role in Cholesterol Synthesis and is Coregulated Transcriptionally. J Lipid Res 2022; 63:100295. [PMID: 36216146 PMCID: PMC9730225 DOI: 10.1016/j.jlr.2022.100295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 08/30/2022] [Accepted: 10/03/2022] [Indexed: 11/06/2022] Open
Abstract
The enzymatic pathway of cholesterol biosynthesis has been well characterized. However, there remain several potential interacting proteins that may play ancillary roles in the regulation of cholesterol production. Here, we identified ERG28 (chromosome 14 open reading frame 1 [C14orf1]), a homologue of the yeast protein Erg28p, as a player in mammalian cholesterol synthesis. ERG28 is conserved from yeast to humans but has been largely overlooked in mammals. Using quantitative RT-PCR, luciferase assays, and publicly available chromatin immunoprecipitation sequencing data, we found that transcription of this gene is driven by the transcription factor SREBP-2, akin to most cholesterol synthesis enzymes, as well as identifying sterol-responsive elements and cofactor binding sites in its proximal promoter. Based on a split luciferase system, ERG28 interacted with itself and two enzymes of cholesterol synthesis (NSDHL and SC4MOL). Huh7 ERG28-KO cell lines were generated, revealing reduced total cholesterol levels in sterol-depleted environments. In addition, radiolabeled metabolic flux assays showed a 60-75% reduction in the rate of cholesterol synthesis in the KO versus wild-type cells, which could be rescued by expression of ectopic ERG28. Unexpectedly, KO of ERG28 also impaired the activation of SREBP-2 under sterol-replete conditions, by a yet-to-be defined mechanism. These results indicate that ERG28 is clearly involved in cholesterol synthesis, although the precise role this noncatalytic protein plays in this complex metabolic pathway remains to be fully elucidated. A deeper understanding of ERG28, and other ancillary proteins of cholesterol synthesis, may help inform therapeutic strategies for diseases associated with aberrant cholesterol metabolism.
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Zou Y, Zhang H, Bi F, Tang Q, Xu H. Targeting the key cholesterol biosynthesis enzyme squalene monooxygenasefor cancer therapy. Front Oncol 2022; 12:938502. [PMID: 36091156 PMCID: PMC9449579 DOI: 10.3389/fonc.2022.938502] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 07/26/2022] [Indexed: 11/22/2022] Open
Abstract
Cholesterol metabolism is often dysregulated in cancer. Squalene monooxygenase (SQLE) is the second rate-limiting enzyme involved in cholesterol synthesis. Since the discovery of SQLE dysregulation in cancer, compelling evidence has indicated that SQLE plays a vital role in cancer initiation and progression and is a promising therapeutic target for cancer treatment. In this review, we provide an overview of the role and regulation of SQLE in cancer and summarize the updates of antitumor therapy targeting SQLE.
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Affiliation(s)
- Yuheng Zou
- Department of Medical Oncology, Cancer Center and Laboratory of Molecular Targeted Therapy in Oncology, West China Hospital, Sichuan University, Chengdu, China
| | - Hongying Zhang
- Laboratory of Oncogene, West China Hospital, Sichuan University, Chengdu, China
| | - Feng Bi
- Department of Medical Oncology, Cancer Center and Laboratory of Molecular Targeted Therapy in Oncology, West China Hospital, Sichuan University, Chengdu, China
| | - Qiulin Tang
- Department of Medical Oncology, Cancer Center and Laboratory of Molecular Targeted Therapy in Oncology, West China Hospital, Sichuan University, Chengdu, China
- *Correspondence: Qiulin Tang, ; Huanji Xu,
| | - Huanji Xu
- Department of Medical Oncology, Cancer Center and Laboratory of Molecular Targeted Therapy in Oncology, West China Hospital, Sichuan University, Chengdu, China
- *Correspondence: Qiulin Tang, ; Huanji Xu,
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The MARCHF6 E3 ubiquitin ligase acts as an NADPH sensor for the regulation of ferroptosis. Nat Cell Biol 2022; 24:1239-1251. [PMID: 35941365 DOI: 10.1038/s41556-022-00973-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 06/29/2022] [Indexed: 01/16/2023]
Abstract
Ferroptosis is a unique form of cell death caused by excessive iron-dependent lipid peroxidation. The level of the anabolic reductant NADPH is a biomarker of ferroptosis sensitivity. However, specific regulators that detect cellular NADPH levels, thereby modulating downstream ferroptosis cascades, are largely unknown. We show here that the transmembrane endoplasmic reticulum MARCHF6 E3 ubiquitin ligase recognizes NADPH through its C-terminal regulatory region. This interaction upregulates the E3 ligase activity of MARCHF6, thus downregulating ferroptosis. We also found that MARCHF6 mediates the degradation of the key ferroptosis effectors ACSL4 and p53. Furthermore, inhibiting ferroptosis rescued the growth of MARCHF6-deficient tumours and peri-natal lethality of Marchf6-/- mice. Together, these findings identify MARCHF6 as a previously unknown NADPH sensor in the ubiquitin system and a crucial regulator of ferroptosis.
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Farkas Á, Urlaub H, Bohnsack KE, Schwappach B. Regulated targeting of the monotopic hairpin membrane protein Erg1 requires the GET pathway. J Biophys Biochem Cytol 2022; 221:213228. [PMID: 35587358 PMCID: PMC9123286 DOI: 10.1083/jcb.202201036] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 03/27/2022] [Accepted: 04/12/2022] [Indexed: 02/08/2023] Open
Abstract
The guided entry of tail-anchored proteins (GET) pathway targets C-terminally anchored transmembrane proteins and protects cells from lipotoxicity. Here, we reveal perturbed ergosterol production in ∆get3 cells and demonstrate the sensitivity of GET pathway mutants to the sterol synthesis inhibiting drug terbinafine. Our data uncover a key enzyme of sterol synthesis, the hairpin membrane protein squalene monooxygenase (Erg1), as a non-canonical GET pathway client, thus rationalizing the lipotoxicity phenotypes of GET pathway mutants. Get3 recognizes the hairpin targeting element of Erg1 via its classical client-binding pocket. Intriguingly, we find that the GET pathway is especially important for the acute upregulation of Erg1 induced by low sterol conditions. We further identify several other proteins anchored to the endoplasmic reticulum (ER) membrane exclusively via a hairpin as putative clients of the GET pathway. Our findings emphasize the necessity of dedicated targeting pathways for high-efficiency targeting of particular clients during dynamic cellular adaptation and highlight hairpin proteins as a potential novel class of GET clients.
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Affiliation(s)
- Ákos Farkas
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
| | - Henning Urlaub
- Bioanalytic Mass Spectrometry, Max-Planck Institute for Biophysical Chemistry, Göttingen, Germany.,Bioanalytics, Institute of Clinical Chemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Katherine E Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
| | - Blanche Schwappach
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
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Red Blood Cell Proteasome in Beta-Thalassemia Trait: Topology of Activity and Networking in Blood Bank Conditions. MEMBRANES 2021; 11:membranes11090716. [PMID: 34564533 PMCID: PMC8466122 DOI: 10.3390/membranes11090716] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 09/09/2021] [Accepted: 09/13/2021] [Indexed: 01/19/2023]
Abstract
Proteasomes are multi-catalytic complexes with important roles in protein control. Their activity in stored red blood cells (RBCs) is affected by both storage time and the donor’s characteristics. However, apart from their abundancy in the membrane proteome, not much is known about their topology, activity, and networking during the storage of RBCs from beta-thalassemia trait donors (βThal+). For this purpose, RBC units from fourteen βThal+ donors were fractionated and studied for proteasome activity distribution and interactome through fluorometric and correlation analyses against units of sex- and aged-matched controls. In all the samples examined, we observed a time-dependent translocation and/or activation of the proteasome in the membrane and a tight connection of activity with the oxidative burden of cells. Proteasomes were more active in the βThal+ membranes and supernatants, while the early storage networking of 20S core particles and activities showed a higher degree of connectivity with chaperones, calpains, and peroxiredoxins, which were nonetheless present in all interactomes. Moreover, the βThal+ interactomes were specially enriched in kinases, metabolic enzymes, and proteins differentially expressed in βThal+ membrane, including arginase-1, piezo-1, and phospholipid scramblase. Overall, it seems that βThal+ erythrocytes maintain a considerable “proteo-vigilance” during storage, which is closely connected to their distinct antioxidant dynamics and membrane protein profile.
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