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Xie T, Dong F, Han G, Wu X, Liu P, Zhang Z, Zhong J, Niranjanakumari S, Gable K, Gupta SD, Liu W, Harrison PJ, Campopiano DJ, Dunn TM, Gong X. Collaborative regulation of yeast SPT-Orm2 complex by phosphorylation and ceramide. Cell Rep 2024; 43:113717. [PMID: 38285738 DOI: 10.1016/j.celrep.2024.113717] [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: 09/08/2023] [Revised: 12/14/2023] [Accepted: 01/12/2024] [Indexed: 01/31/2024] Open
Abstract
The homeostatic regulation of serine palmitoyltransferase (SPT) activity in yeast involves N-terminal phosphorylation of Orm proteins, while higher eukaryotes lack these phosphorylation sites. Although recent studies have indicated a conserved ceramide-mediated feedback inhibition of the SPT-ORM/ORMDL complex in higher eukaryotes, its conservation and relationship with phosphorylation regulation in yeast remain unclear. Here, we determine the structure of the yeast SPT-Orm2 complex in a dephosphomimetic state and identify an evolutionarily conserved ceramide-sensing site. Ceramide stabilizes the dephosphomimetic Orm2 in an inhibitory conformation, facilitated by an intramolecular β-sheet between the N- and C-terminal segments of Orm2. Moreover, we find that a phosphomimetic mutant of Orm2, positioned adjacent to its intramolecular β-sheet, destabilizes the inhibitory conformation of Orm2. Taken together, our findings suggest that both Orm dephosphorylation and ceramide binding are crucial for suppressing SPT activity in yeast. This highlights a distinctive regulatory mechanism in yeast involving the collaborative actions of phosphorylation and ceramide.
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Affiliation(s)
- Tian Xie
- Department of Chemical Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Feitong Dong
- Department of Chemical Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Gongshe Han
- Department of Biochemistry and Molecular Biology, Uniformed Services University of Health Sciences, Bethesda, MD 20814, USA
| | - Xinyue Wu
- Department of Chemical Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Peng Liu
- Department of Chemical Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Zike Zhang
- Department of Chemical Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Jianlong Zhong
- Department of Chemical Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Somashekarappa Niranjanakumari
- Department of Biochemistry and Molecular Biology, Uniformed Services University of Health Sciences, Bethesda, MD 20814, USA
| | - Kenneth Gable
- Department of Biochemistry and Molecular Biology, Uniformed Services University of Health Sciences, Bethesda, MD 20814, USA
| | - Sita D Gupta
- Department of Biochemistry and Molecular Biology, Uniformed Services University of Health Sciences, Bethesda, MD 20814, USA
| | - Wenchen Liu
- Department of Chemical Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Peter J Harrison
- School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ, UK
| | | | - Teresa M Dunn
- Department of Biochemistry and Molecular Biology, Uniformed Services University of Health Sciences, Bethesda, MD 20814, USA.
| | - Xin Gong
- Department of Chemical Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; Institute for Biological Electron Microscopy, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China.
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2
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Mohassel P, Abdullah M, Eichler FS, Dunn TM. Serine Palmitoyltransferase (SPT)-related Neurodegenerative and Neurodevelopmental Disorders. J Neuromuscul Dis 2024; 11:735-747. [PMID: 38788085 PMCID: PMC11307022 DOI: 10.3233/jnd-240014] [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] [Accepted: 04/22/2024] [Indexed: 05/26/2024]
Abstract
Motor neuron diseases and peripheral neuropathies are heterogeneous groups of neurodegenerative disorders that manifest with distinct symptoms due to progressive dysfunction or loss of specific neuronal subpopulations during different stages of development. A few monogenic, neurodegenerative diseases associated with primary metabolic disruptions of sphingolipid biosynthesis have been recently discovered. Sphingolipids are a subclass of lipids that form critical building blocks of all cellular and subcellular organelle membranes including the membrane components of the nervous system cells. They are especially abundant within the lipid portion of myelin. In this review, we will focus on our current understanding of disease phenotypes in three monogenic, neuromuscular diseases associated with pathogenic variants in components of serine palmitoyltransferase, the first step in sphingolipid biosynthesis. These include hereditary sensory and autonomic neuropathy type 1 (HSAN1), a sensory predominant peripheral neuropathy, and two neurodegenerative disorders: juvenile amyotrophic lateral sclerosis affecting the upper and lower motor neurons with sparing of sensory neurons, and a complicated form of hereditary spastic paraplegia with selective involvement of the upper motor neurons and more broad CNS neurodegeneration. We will also review our current understanding of disease pathomechanisms, therapeutic approaches, and the unanswered questions to explore in future studies.
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Affiliation(s)
- Payam Mohassel
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Meher Abdullah
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Florian S. Eichler
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Teresa M. Dunn
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
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3
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Esch BM, Walter S, Schmidt O, Fröhlich F. Identification of distinct active pools of yeast serine palmitoyltransferase in sub-compartments of the ER. J Cell Sci 2023; 136:jcs261353. [PMID: 37982431 DOI: 10.1242/jcs.261353] [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: 05/22/2023] [Accepted: 11/09/2023] [Indexed: 11/21/2023] Open
Abstract
Sphingolipids (SPs) are one of the three major lipid classes in eukaryotic cells and serve as structural components of the plasma membrane. The rate-limiting step in SP biosynthesis is catalyzed by the serine palmitoyltransferase (SPT). In budding yeast (Saccharomyces cerevisiae), SPT is negatively regulated by the two proteins, Orm1 and Orm2. Regulating SPT activity enables cells to adapt SP metabolism to changing environmental conditions. Therefore, the Orm proteins are phosphorylated by two signaling pathways originating from either the plasma membrane or the lysosome (or vacuole in yeast). Moreover, uptake of exogenous serine is necessary for the regulation of SP biosynthesis, which suggests the existence of differentially regulated SPT pools based on their intracellular localization. However, measuring lipid metabolic enzyme activity in different cellular sub-compartments has been challenging. Combining a nanobody recruitment approach with SP flux analysis, we show that the nuclear endoplasmic reticulum (ER)-localized SPT and the peripheral ER localized SPT pools are differentially active. Thus, our data add another layer to the complex network of SPT regulation. Moreover, combining lipid metabolic enzyme re-localization with flux analysis serves as versatile tool to measure lipid metabolism with subcellular resolution.
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Affiliation(s)
- Bianca M Esch
- Osnabrück University, Department of Biology-Chemistry, Bioanalytical Chemistry Section, Barbarastrasse 13, 49076 Osnabrück, Germany
- Osnabrück University, Center for Cellular Nanoanalytic Osnabrück (CellNanOs), Barbarastrasse 11, 49076 Osnabrück, Germany
| | - Stefan Walter
- Osnabrück University, Center for Cellular Nanoanalytic Osnabrück (CellNanOs), Barbarastrasse 11, 49076 Osnabrück, Germany
| | - Oliver Schmidt
- Institute of Cell Biology, Biocenter Innsbruck, Medical University of Innsbruck, Innrain 80, 6020 Innsbruck, Austria
| | - Florian Fröhlich
- Osnabrück University, Department of Biology-Chemistry, Bioanalytical Chemistry Section, Barbarastrasse 13, 49076 Osnabrück, Germany
- Osnabrück University, Center for Cellular Nanoanalytic Osnabrück (CellNanOs), Barbarastrasse 11, 49076 Osnabrück, Germany
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4
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Schäfer JH, Körner C, Esch BM, Limar S, Parey K, Walter S, Januliene D, Moeller A, Fröhlich F. Structure of the ceramide-bound SPOTS complex. Nat Commun 2023; 14:6196. [PMID: 37794019 PMCID: PMC10550967 DOI: 10.1038/s41467-023-41747-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 09/05/2023] [Indexed: 10/06/2023] Open
Abstract
Sphingolipids are structural membrane components that also function in cellular stress responses. The serine palmitoyltransferase (SPT) catalyzes the rate-limiting step in sphingolipid biogenesis. Its activity is tightly regulated through multiple binding partners, including Tsc3, Orm proteins, ceramides, and the phosphatidylinositol-4-phosphate (PI4P) phosphatase Sac1. The structural organization and regulatory mechanisms of this complex are not yet understood. Here, we report the high-resolution cryo-EM structures of the yeast SPT in complex with Tsc3 and Orm1 (SPOT) as dimers and monomers and a monomeric complex further carrying Sac1 (SPOTS). In all complexes, the tight interaction of the downstream metabolite ceramide and Orm1 reveals the ceramide-dependent inhibition. Additionally, observation of ceramide and ergosterol binding suggests a co-regulation of sphingolipid biogenesis and sterol metabolism within the SPOTS complex.
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Affiliation(s)
- Jan-Hannes Schäfer
- Osnabrück University Department of Biology/Chemistry Structural Biology section, 49076, Osnabrück, Germany
| | - Carolin Körner
- Osnabrück University Department of Biology/Chemistry Bioanalytical Chemistry section, 49076, Osnabrück, Germany
| | - Bianca M Esch
- Osnabrück University Department of Biology/Chemistry Bioanalytical Chemistry section, 49076, Osnabrück, Germany
| | - Sergej Limar
- Osnabrück University Department of Biology/Chemistry Bioanalytical Chemistry section, 49076, Osnabrück, Germany
| | - Kristian Parey
- Osnabrück University Department of Biology/Chemistry Structural Biology section, 49076, Osnabrück, Germany
- Osnabrück University Center of Cellular Nanoanalytic Osnabrück (CellNanOs), 49076, Osnabrück, Germany
| | - Stefan Walter
- Osnabrück University Center of Cellular Nanoanalytic Osnabrück (CellNanOs), 49076, Osnabrück, Germany
| | - Dovile Januliene
- Osnabrück University Department of Biology/Chemistry Structural Biology section, 49076, Osnabrück, Germany.
- Osnabrück University Center of Cellular Nanoanalytic Osnabrück (CellNanOs), 49076, Osnabrück, Germany.
| | - Arne Moeller
- Osnabrück University Department of Biology/Chemistry Structural Biology section, 49076, Osnabrück, Germany.
- Osnabrück University Center of Cellular Nanoanalytic Osnabrück (CellNanOs), 49076, Osnabrück, Germany.
| | - Florian Fröhlich
- Osnabrück University Department of Biology/Chemistry Bioanalytical Chemistry section, 49076, Osnabrück, Germany.
- Osnabrück University Center of Cellular Nanoanalytic Osnabrück (CellNanOs), 49076, Osnabrück, Germany.
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5
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Usmani SA, Kumar M, Arya K, Ali B, Bhardwaj N, Gaur NA, Prasad R, Singh A. Beyond membrane components: uncovering the intriguing world of fungal sphingolipid synthesis and regulation. Res Microbiol 2023; 174:104087. [PMID: 37328042 DOI: 10.1016/j.resmic.2023.104087] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 06/06/2023] [Accepted: 06/07/2023] [Indexed: 06/18/2023]
Abstract
Sphingolipids (SLs) are essential to fungal survival and represent a major class of structural and signaling lipids. Unique SL structures and their biosynthetic enzymes in filamentous fungi make them an ideal drug target. Several studies have contributed towards the functional characterization of specific SL metabolism genes, which have been complemented by advanced lipidomics methods which allow accurate identification and quantification of lipid structures and pathway mapping. These studies have provided a better understanding of SL biosynthesis, degradation and regulation networks in filamentous fungi, which are discussed and elaborated here.
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Affiliation(s)
- Sana Akhtar Usmani
- Department of Biochemistry, University of Lucknow, Lucknow, Uttar Pradesh, 226024, India
| | - Mohit Kumar
- Amity Institute of Integrative Science and Health and Amity Institute of Biotechnology, Amity University Gurgaon, Haryana, India; International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India
| | - Khushboo Arya
- Department of Biochemistry, University of Lucknow, Lucknow, Uttar Pradesh, 226024, India
| | - Basharat Ali
- Amity Institute of Integrative Science and Health and Amity Institute of Biotechnology, Amity University Gurgaon, Haryana, India
| | - Nitin Bhardwaj
- Department of Zoology and Environmental Science, Gurukula Kangri Vishwavidyalaya, Haridwar, Uttarakhand 249404, India
| | - Naseem Akhtar Gaur
- International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India
| | - Rajendra Prasad
- Amity Institute of Integrative Science and Health and Amity Institute of Biotechnology, Amity University Gurgaon, Haryana, India
| | - Ashutosh Singh
- Department of Biochemistry, University of Lucknow, Lucknow, Uttar Pradesh, 226024, India.
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6
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Madaan K, Bari VK. Emerging Role of Sphingolipids in Amphotericin B Drug Resistance. Microb Drug Resist 2023. [PMID: 37327022 DOI: 10.1089/mdr.2022.0353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023] Open
Abstract
Invasive fungal infections in humans are common in people with compromised immune systems and are difficult to treat, resulting in high mortality. Amphotericin B (AmB) is one of the main antifungal drugs available to treat these infections. AmB binds with plasma membrane ergosterol, causing leakage of cellular ions and promoting cell death. The increasing use of available antifungal drugs to combat pathogenic fungal infections has led to the development of drug resistance. AmB resistance is not very common and is usually caused by changes in the amount or type of ergosterol or changes in the cell wall. Intrinsic AmB resistance occurs in the absence of AmB exposure, whereas acquired AmB resistance can develop during treatment. However, clinical resistance arises due to treatment failure with AmB and depends on multiple factors such as the pharmacokinetics of AmB, infectious fungal species, and host immune status. Candida albicans is a common opportunistic pathogen that can cause superficial infections of the skin and mucosal surfaces, thrush, to life-threatening systemic or invasive infections. In addition, immunocompromised individuals are more susceptible to systemic infections caused by Candida, Aspergillus, and Cryptococcus. Several antifungal drugs with different modes of action are used to treat systemic to invasive fungal infections and are approved for clinical use in the treatment of fungal diseases. However, C. albicans can develop a variety of defenses against antifungal medications. In fungi, plasma membrane sphingolipid molecules could interact with ergosterol, which can lead to the alteration of drug susceptibilities such as AmB. In this review, we mainly summarize the role of sphingolipid molecules and their regulators in AmB resistance.
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Affiliation(s)
- Kashish Madaan
- Department of Biochemistry, School of Basic Sciences, Central University of Punjab, Bathinda, India
| | - Vinay Kumar Bari
- Department of Biochemistry, School of Basic Sciences, Central University of Punjab, Bathinda, India
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7
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Bhaduri S, Aguayo A, Ohno Y, Proietto M, Jung J, Wang I, Kandel R, Singh N, Ibrahim I, Fulzele A, Bennett EJ, Kihara A, Neal SE. An ERAD-independent role for rhomboid pseudoprotease Dfm1 in mediating sphingolipid homeostasis. EMBO J 2023; 42:e112275. [PMID: 36350249 PMCID: PMC9929635 DOI: 10.15252/embj.2022112275] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 09/20/2022] [Accepted: 10/19/2022] [Indexed: 11/11/2022] Open
Abstract
Nearly one-third of nascent proteins are initially targeted to the endoplasmic reticulum (ER), where they are correctly folded and assembled before being delivered to their final cellular destinations. To prevent the accumulation of misfolded membrane proteins, ER-associated degradation (ERAD) removes these client proteins from the ER membrane to the cytosol in a process known as retrotranslocation. Our previous work demonstrated that rhomboid pseudoprotease Dfm1 is involved in the retrotranslocation of ubiquitinated membrane integral ERAD substrates. Herein, we found that Dfm1 associates with the SPOTS complex, which is composed of serine palmitoyltransferase (SPT) enzymes and accessory components that are critical for catalyzing the first rate-limiting step of the sphingolipid biosynthesis pathway. Furthermore, Dfm1 employs an ERAD-independent role for facilitating the ER export and endosome- and Golgi-associated degradation (EGAD) of Orm2, which is a major antagonist of SPT activity. Given that the accumulation of human Orm2 homologs, ORMDLs, is associated with various pathologies, our study serves as a molecular foothold for understanding how dysregulation of sphingolipid metabolism leads to various diseases.
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Affiliation(s)
- Satarupa Bhaduri
- Department of Cell and Developmental Biology, School of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
| | - Analine Aguayo
- Department of Cell and Developmental Biology, School of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
| | - Yusuke Ohno
- Laboratory of Biochemistry, Faculty of Pharmaceutical SciencesHokkaido UniversitySapporoJapan
| | - Marco Proietto
- Department of Cell and Developmental Biology, School of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
| | - Jasmine Jung
- Department of Cell and Developmental Biology, School of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
| | - Isabel Wang
- Department of Cell and Developmental Biology, School of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
| | - Rachel Kandel
- Department of Cell and Developmental Biology, School of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
| | - Narinderbir Singh
- Department of Cell and Developmental Biology, School of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
| | - Ikran Ibrahim
- Department of Cell and Developmental Biology, School of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
| | - Amit Fulzele
- Present address:
Institute of Molecular BiologyMainzGermany
| | - Eric J Bennett
- Department of Cell and Developmental Biology, School of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
| | - Akio Kihara
- Laboratory of Biochemistry, Faculty of Pharmaceutical SciencesHokkaido UniversitySapporoJapan
| | - Sonya E Neal
- Department of Cell and Developmental Biology, School of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
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8
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Wang P, Wei Q, Li H, Wu ZY. Clinical feature difference between juvenile amyotrophic lateral sclerosis with SPTLC1 and FUS mutations. Chin Med J (Engl) 2023; 136:176-183. [PMID: 36801857 PMCID: PMC10106144 DOI: 10.1097/cm9.0000000000002495] [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: 04/29/2022] [Indexed: 02/23/2023] Open
Abstract
BACKGROUND Juvenile amyotrophic lateral sclerosis (JALS) is an uncommon form of amyotrophic lateral sclerosis whose age at onset (AAO) is defined as prior to 25 years. FUS mutations are the most common cause of JALS. SPTLC1 was recently identified as a disease-causative gene for JALS, which has rarely been reported in Asian populations. Little is known regarding the difference in clinical features between JALS patients carrying FUS and SPTLC1 mutations. This study aimed to screen mutations in JALS patients and to compare the clinical features between JALS patients with FUS and SPTLC1 mutations. METHODS Sixteen JALS patients were enrolled, including three newly recruited patients between July 2015 and August 2018 from the Second Affiliated Hospital, Zhejiang University School of Medicine. Mutations were screened by whole-exome sequencing. In addition, clinical features such as AAO, onset site and disease duration were extracted and compared between JALS patients carrying FUS and SPTLC1 mutations through a literature review. RESULTS A novel and de novo SPTLC1 mutation (c.58G>A, p.A20T) was identified in a sporadic patient. Among 16 JALS patients, 7/16 carried FUS mutations and 5/16 carried respective SPTLC1 , SETX , NEFH , DCTN1 , and TARDBP mutations. Compared with FUS mutation patients, those with SPTLC1 mutations had an earlier AAO (7.9 ± 4.6 years vs. 18.1 ± 3.9 years, P < 0.01), much longer disease duration (512.0 [416.7-607.3] months vs. 33.4 [21.6-45.1] months, P < 0.01), and no onset of bulbar. CONCLUSION Our findings expand the genetic and phenotypic spectrum of JALS and help to better understand the genotype-phenotype correlation of JALS.
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Affiliation(s)
- Peishan Wang
- Department of Neurology, Second Affiliated Hospital, Zhejiang University School of Medicine, and Key Laboratory of Medical Neurobiology of Zhejiang Province, Hangzhou, Zhejiang 310009, China
- Department of Medical Genetics, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009, China
| | - Qiao Wei
- Department of Neurology, Second Affiliated Hospital, Zhejiang University School of Medicine, and Key Laboratory of Medical Neurobiology of Zhejiang Province, Hangzhou, Zhejiang 310009, China
- Department of Medical Genetics, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009, China
| | - Hongfu Li
- Department of Neurology, Second Affiliated Hospital, Zhejiang University School of Medicine, and Key Laboratory of Medical Neurobiology of Zhejiang Province, Hangzhou, Zhejiang 310009, China
- Department of Medical Genetics, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009, China
| | - Zhi-Ying Wu
- Department of Neurology, Second Affiliated Hospital, Zhejiang University School of Medicine, and Key Laboratory of Medical Neurobiology of Zhejiang Province, Hangzhou, Zhejiang 310009, China
- Department of Medical Genetics, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009, China
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9
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Lone MA, Aaltonen MJ, Zidell A, Pedro HF, Morales Saute JA, Mathew S, Mohassel P, Bönnemann CG, Shoubridge EA, Hornemann T. SPTLC1 variants associated with ALS produce distinct sphingolipid signatures through impaired interaction with ORMDL proteins. J Clin Invest 2022; 132:161908. [PMID: 35900868 PMCID: PMC9479574 DOI: 10.1172/jci161908] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 07/26/2022] [Indexed: 11/17/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that affects motor neurons. Mutations in the SPTLC1 subunit of serine palmitoyltransferase (SPT), which catalyzes the first step in the de novo synthesis of sphingolipids (SLs), cause childhood-onset ALS. SPTLC1-ALS variants map to a transmembrane domain that interacts with ORMDL proteins, negative regulators of SPT activity. We show that ORMDL binding to the holoenzyme complex is impaired in cells expressing pathogenic SPTLC1-ALS alleles, resulting in increased SL synthesis and a distinct lipid signature. C-terminal SPTLC1 variants cause peripheral hereditary sensory and autonomic neuropathy type 1 (HSAN1) due to the synthesis of 1-deoxysphingolipids (1-deoxySLs) that form when SPT metabolizes L-alanine instead of L-serine. Limiting L-serine availability in SPTLC1-ALS-expressing cells increased 1-deoxySL and shifted the SL profile from an ALS to an HSAN1-like signature. This effect was corroborated in an SPTLC1-ALS pedigree in which the index patient uniquely presented with an HSAN1 phenotype, increased 1-deoxySL levels, and an L-serine deficiency. These data demonstrate how pathogenic variants in different domains of SPTLC1 give rise to distinct clinical presentations that are nonetheless modifiable by substrate availability.
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Affiliation(s)
- Museer A. Lone
- Institute of Clinical Chemistry, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Mari J. Aaltonen
- Montreal Neurological Institute and,Department of Human Genetics, McGill University, Montreal, Canada
| | - Aliza Zidell
- Center for Genetic and Genomic Medicine, Hackensack University Medical Center, Hackensack, New Jersey, USA
| | - Helio F. Pedro
- Center for Genetic and Genomic Medicine, Hackensack University Medical Center, Hackensack, New Jersey, USA.,Center for Genetic and Genomic Medicine, Hackensack University Medical Center, Hackensack Meridian School of Medicine, Hackensack, New Jersey, USA
| | - Jonas A. Morales Saute
- Medical Genetics Division and Neurology Division, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.,Graduate Program in Medicine, Medical Sciences, and Internal Medicine Department, Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Shalett Mathew
- Institute of Clinical Chemistry, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Payam Mohassel
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, Maryland, USA
| | - Carsten G. Bönnemann
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, Maryland, USA
| | - Eric A. Shoubridge
- Montreal Neurological Institute and,Department of Human Genetics, McGill University, Montreal, Canada
| | - Thorsten Hornemann
- Institute of Clinical Chemistry, University Hospital Zurich, University of Zurich, Zurich, Switzerland
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10
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Mallik S, Tawfik DS, Levy ED. How gene duplication diversifies the landscape of protein oligomeric state and function. Curr Opin Genet Dev 2022; 76:101966. [PMID: 36007298 PMCID: PMC9548406 DOI: 10.1016/j.gde.2022.101966] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 07/01/2022] [Accepted: 07/08/2022] [Indexed: 11/29/2022]
Abstract
Oligomeric proteins are central to cellular life and the duplication and divergence of their genes is a key driver of evolutionary innovations. The duplication of a gene coding for an oligomeric protein has numerous possible outcomes, which motivates questions on the relationship between structural and functional divergence. How do protein oligomeric states diversify after gene duplication? In the simple case of duplication of a homo-oligomeric protein gene, what properties can influence the fate of descendant paralogs toward forming independent homomers or maintaining their interaction as a complex? Furthermore, how are functional innovations associated with the diversification of oligomeric states? Here, we review recent literature and present specific examples in an attempt to illustrate and answer these questions.
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Affiliation(s)
- Saurav Mallik
- Department of Chemical and Structural Biology, The Weizmann Institute of Science, Rehovot 7610001, Israel; Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 7610001, Israel.
| | - Dan S Tawfik
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Emmanuel D Levy
- Department of Chemical and Structural Biology, The Weizmann Institute of Science, Rehovot 7610001, Israel.
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11
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Contribution of specific ceramides to obesity-associated metabolic diseases. Cell Mol Life Sci 2022; 79:395. [PMID: 35789435 PMCID: PMC9252958 DOI: 10.1007/s00018-022-04401-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 05/20/2022] [Accepted: 05/26/2022] [Indexed: 12/04/2022]
Abstract
Ceramides are a heterogeneous group of bioactive membrane sphingolipids that play specialized regulatory roles in cellular metabolism depending on their characteristic fatty acyl chain lengths and subcellular distribution. As obesity progresses, certain ceramide molecular species accumulate in metabolic tissues and cause cell-type-specific lipotoxic reactions that disrupt metabolic homeostasis and lead to the development of cardiometabolic diseases. Several mechanisms for ceramide action have been inferred from studies in vitro, but only recently have we begun to better understand the acyl chain length specificity of ceramide-mediated signaling in the context of physiology and disease in vivo. New discoveries show that specific ceramides affect various metabolic pathways and that global or tissue-specific reduction in selected ceramide pools in obese rodents is sufficient to improve metabolic health. Here, we review the tissue-specific regulation and functions of ceramides in obesity, thus highlighting the emerging concept of selectively inhibiting production or action of ceramides with specific acyl chain lengths as novel therapeutic strategies to ameliorate obesity-associated diseases.
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12
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Shu H, Peng Y, Hang W, Li N, Zhou N, Wang DW. Emerging Roles of Ceramide in Cardiovascular Diseases. Aging Dis 2022; 13:232-245. [PMID: 35111371 PMCID: PMC8782558 DOI: 10.14336/ad.2021.0710] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 07/10/2021] [Indexed: 12/15/2022] Open
Abstract
Ceramide is a core molecule of sphingolipid metabolism that causes selective insulin resistance and dyslipidemia. Research on its involvement in cardiovascular diseases has grown rapidly. In resting cells, ceramide levels are extremely low, while they rapidly accumulate upon encountering external stimuli. Recently, the regulation of ceramide levels under pathological conditions, including myocardial infarction, hypertension, and atherosclerosis, has drawn great attention. Increased ceramide levels are strongly associated with adverse cardiovascular risks and events while inhibiting the synthesis of ceramide or accelerating its degradation improves a variety of cardiovascular diseases. In this article, we summarize the role of ceramide in cardiovascular disease, investigate the possible application of ceramide as a new diagnostic biomarker and a therapeutic target for cardiovascular disorders, and highlight the remaining problems.
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Affiliation(s)
- Hongyang Shu
- 1Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430000, China.,2Hubei Key Laboratory of Genetics and Molecular Mechanism of Cardiologic Disorders, Huazhong University of Science and Technology, Wuhan 430000, China
| | - Yizhong Peng
- 3Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430000, China
| | - Weijian Hang
- 1Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430000, China.,2Hubei Key Laboratory of Genetics and Molecular Mechanism of Cardiologic Disorders, Huazhong University of Science and Technology, Wuhan 430000, China
| | - Na Li
- 1Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430000, China.,2Hubei Key Laboratory of Genetics and Molecular Mechanism of Cardiologic Disorders, Huazhong University of Science and Technology, Wuhan 430000, China
| | - Ning Zhou
- 1Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430000, China.,2Hubei Key Laboratory of Genetics and Molecular Mechanism of Cardiologic Disorders, Huazhong University of Science and Technology, Wuhan 430000, China
| | - Dao Wen Wang
- 1Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430000, China.,2Hubei Key Laboratory of Genetics and Molecular Mechanism of Cardiologic Disorders, Huazhong University of Science and Technology, Wuhan 430000, China
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13
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Kuo A, Checa A, Niaudet C, Jung B, Fu Z, Wheelock CE, Singh SA, Aikawa M, Smith LE, Proia RL, Hla T. Murine endothelial serine palmitoyltransferase 1 (SPTLC1) is required for vascular development and systemic sphingolipid homeostasis. eLife 2022; 11:78861. [PMID: 36197001 PMCID: PMC9578713 DOI: 10.7554/elife.78861] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 10/04/2022] [Indexed: 02/04/2023] Open
Abstract
Serine palmitoyl transferase (SPT), the rate-limiting enzyme in the de novo synthesis of sphingolipids (SL), is needed for embryonic development, physiological homeostasis, and response to stress. The functions of de novo SL synthesis in vascular endothelial cells (EC), which line the entire circulatory system, are not well understood. Here, we show that the de novo SL synthesis in EC not only regulates vascular development but also maintains circulatory and peripheral organ SL levels. Mice with an endothelial-specific gene knockout of SPTLC1 (Sptlc1 ECKO), an essential subunit of the SPT complex, exhibited reduced EC proliferation and tip/stalk cell differentiation, resulting in delayed retinal vascular development. In addition, Sptlc1 ECKO mice had reduced retinal neovascularization in the oxygen-induced retinopathy model. Mechanistic studies suggest that EC SL produced from the de novo pathway are needed for lipid raft formation and efficient VEGF signaling. Post-natal deletion of the EC Sptlc1 also showed rapid reduction of several SL metabolites in plasma, red blood cells, and peripheral organs (lung and liver) but not in the retina, part of the central nervous system (CNS). In the liver, EC de novo SL synthesis was important for acetaminophen-induced rapid ceramide elevation and hepatotoxicity. These results suggest that EC-derived SL metabolites are in constant flux between the vasculature, circulatory elements, and parenchymal cells of non-CNS organs. Taken together, our data point to the central role of the endothelial SL biosynthesis in maintaining vascular development, neovascular proliferation, non-CNS tissue metabolic homeostasis, and hepatocyte response to stress.
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Affiliation(s)
- Andrew Kuo
- Vascular Biology Program, Boston Children’s Hospital, Department of Surgery, Harvard Medical SchoolBostonUnited States
| | - Antonio Checa
- Unit of Integrative Metabolomics, Institute of Environmental Medicine, Karolinska InstituteStockholmSweden
| | - Colin Niaudet
- Vascular Biology Program, Boston Children’s Hospital, Department of Surgery, Harvard Medical SchoolBostonUnited States
| | - Bongnam Jung
- Vascular Biology Program, Boston Children’s Hospital, Department of Surgery, Harvard Medical SchoolBostonUnited States
| | - Zhongjie Fu
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical SchoolBostonUnited States
| | - Craig E Wheelock
- Unit of Integrative Metabolomics, Institute of Environmental Medicine, Karolinska InstituteStockholmSweden,Department of Respiratory Medicine and Allergy, Karolinska University HospitalStockholmSweden,Gunma University Initiative for Advanced Research, Gunma UniversityMaebashiJapan
| | - Sasha A Singh
- Center for Interdisciplinary Cardiovascular Sciences, Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical SchoolBostonUnited States
| | - Masanori Aikawa
- Center for Interdisciplinary Cardiovascular Sciences, Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical SchoolBostonUnited States
| | - Lois E Smith
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical SchoolBostonUnited States
| | - Richard L Proia
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesdaUnited States
| | - Timothy Hla
- Vascular Biology Program, Boston Children’s Hospital, Department of Surgery, Harvard Medical SchoolBostonUnited States
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14
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Seo SY, Kim YJ, Kim J, Nam MH, Park KY. Phytosphingosine induces systemic acquired resistance through activation of sphingosine kinase. PLANT DIRECT 2021; 5:e351. [PMID: 34622122 PMCID: PMC8483070 DOI: 10.1002/pld3.351] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 10/13/2020] [Accepted: 09/08/2021] [Indexed: 05/11/2023]
Abstract
Phytosphingosine (PHS) is a naturally occurring bioactive sphingolipid molecule. Intermediates such as sphingolipid long-chain bases (LCBs) in sphingolipid biosynthesis have been shown to have important roles as signaling molecules. PHS treatment caused rapid cell damage and upregulated the generation of reactive oxygen species (ROS) and ethylene in tobacco plants. These events were followed by the induction of sphingosine kinase (SphK) in a biphasic manner, which metabolized PHS to phytosphingosine-1-phosphate (PHS-1-P). On the other hand, a PHS treatment with a virulent pathogen, Phytophthora parasitica var. nicotianae (Ppn), alleviated the pathogen-induced cell damage and reduced the growth of Ppn. A Ppn infection increased the PHS and PHS-1-P levels significantly in the upper part of the leaves at the infection site at the later stage. In addition, Ppn increased the transcription levels of serine palmitoyltransferase (LCB1 and LCB2) for sphingolipid biosynthesis at the later stage, which was enhanced further by PHS. Moreover, the PHS treatment increased the transcription and activity of SphK, which was accompanied by prominent increases in the transcription levels of ROS-detoxifying enzymes and PR proteins in the later phase of the pathogen infection. Overall, the PHS-induced resistant effects were prominent during the necrotic stage of this hemibiotrophic infection, indicating that it is more beneficial for inhibiting the pathogenicity on necrotic cell death. Phosphorylated LCBs reduced the pathogen-induced cell damage significantly in this stage. These results suggest that the selective channeling of sphingolipids into phosphorylated forms has a pro-survival effect on plant immunity.
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Affiliation(s)
- So Yeon Seo
- Department of Biology Sunchon National University Suncheon Republic of Korea
| | - Yu Jung Kim
- Department of Biology Sunchon National University Suncheon Republic of Korea
| | - Jinwoo Kim
- Seoul Center Korea Basic Science Institute (KBSI) Seoul Republic of Korea
| | - Myung Hee Nam
- Seoul Center Korea Basic Science Institute (KBSI) Seoul Republic of Korea
| | - Ky Young Park
- Department of Biology Sunchon National University Suncheon Republic of Korea
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15
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Mohassel P, Donkervoort S, Lone MA, Nalls M, Gable K, Gupta SD, Foley AR, Hu Y, Saute JAM, Moreira AL, Kok F, Introna A, Logroscino G, Grunseich C, Nickolls AR, Pourshafie N, Neuhaus SB, Saade D, Gangfuß A, Kölbel H, Piccus Z, Le Pichon CE, Fiorillo C, Ly CV, Töpf A, Brady L, Specht S, Zidell A, Pedro H, Mittelmann E, Thomas FP, Chao KR, Konersman CG, Cho MT, Brandt T, Straub V, Connolly AM, Schara U, Roos A, Tarnopolsky M, Höke A, Brown RH, Lee CH, Hornemann T, Dunn TM, Bönnemann CG. Childhood amyotrophic lateral sclerosis caused by excess sphingolipid synthesis. Nat Med 2021; 27:1197-1204. [PMID: 34059824 PMCID: PMC9309980 DOI: 10.1038/s41591-021-01346-1] [Citation(s) in RCA: 80] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 04/09/2021] [Indexed: 02/06/2023]
Abstract
Amyotrophic lateral sclerosis (ALS) is a progressive, neurodegenerative disease of the lower and upper motor neurons with sporadic or hereditary occurrence. Age of onset, pattern of motor neuron degeneration and disease progression vary widely among individuals with ALS. Various cellular processes may drive ALS pathomechanisms, but a monogenic direct metabolic disturbance has not been causally linked to ALS. Here we show SPTLC1 variants that result in unrestrained sphingoid base synthesis cause a monogenic form of ALS. We identified four specific, dominantly acting SPTLC1 variants in seven families manifesting as childhood-onset ALS. These variants disrupt the normal homeostatic regulation of serine palmitoyltransferase (SPT) by ORMDL proteins, resulting in unregulated SPT activity and elevated levels of canonical SPT products. Notably, this is in contrast with SPTLC1 variants that shift SPT amino acid usage from serine to alanine, result in elevated levels of deoxysphingolipids and manifest with the alternate phenotype of hereditary sensory and autonomic neuropathy. We custom designed small interfering RNAs that selectively target the SPTLC1 ALS allele for degradation, leave the normal allele intact and normalize sphingolipid levels in vitro. The role of primary metabolic disturbances in ALS has been elusive; this study defines excess sphingolipid biosynthesis as a fundamental metabolic mechanism for motor neuron disease.
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Affiliation(s)
- Payam Mohassel
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Sandra Donkervoort
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Museer A Lone
- Institute of Clinical Chemistry, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Matthew Nalls
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Kenneth Gable
- Department of Biochemistry and Molecular Biology, Uniformed Services University of Health Sciences, Bethesda, MD, USA
| | - Sita D Gupta
- Department of Biochemistry and Molecular Biology, Uniformed Services University of Health Sciences, Bethesda, MD, USA
| | - A Reghan Foley
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Ying Hu
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Jonas Alex Morales Saute
- Medical Genetics division and Neurology division, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil; Graduate Program in Medicine: Medical Sciences, and Internal Medicine Department; Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Ana Lucila Moreira
- Neurology Department, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
| | - Fernando Kok
- Neurogenetics Outpatient Service, Neurology Department, Hospital das Clínicas da Universidade de São Paulo, São Paulo, Brazil and Mendelics, São Paulo, Brazil
| | - Alessandro Introna
- Neurology Unit, Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari 'Aldo Moro', Bari, Italy
| | - Giancarlo Logroscino
- Neurology Unit, Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari 'Aldo Moro', Bari, Italy
- Department of Clinical Research in Neurology, Center for Neurodegenerative Diseases and the Aging Brain, University of Bari at 'Pia Fondazione Card G. Panico' Hospital Tricase (Le), Bari, Italy
| | - Christopher Grunseich
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Alec R Nickolls
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Naemeh Pourshafie
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Sarah B Neuhaus
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Dimah Saade
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Andrea Gangfuß
- Department of Paediatric Neurology, Center for Neuromuscular Disorders in Children and Adolescents, University Clinic Essen, University of Duisburg-Essen, Duisburg-Essen, Germany
| | - Heike Kölbel
- Department of Paediatric Neurology, Center for Neuromuscular Disorders in Children and Adolescents, University Clinic Essen, University of Duisburg-Essen, Duisburg-Essen, Germany
| | - Zoe Piccus
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Claire E Le Pichon
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Chiara Fiorillo
- Paediatric Neurology and Muscular Diseases Unit, G. Gaslini Institute and Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health University of Genoa, Genoa, Italy
| | - Cindy V Ly
- Department of Neurology, Washington University in Saint Louis School of Medicine, Saint Louis, MO, USA
| | - Ana Töpf
- John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Lauren Brady
- Division of Neuromuscular & Neurometabolic Disorders, Department of Paediatrics, McMaster University, Hamilton Health Sciences Centre, Hamilton, Ontario, Canada
| | - Sabine Specht
- John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Aliza Zidell
- Center for Genetic and Genomic Medicine, Hackensack University Medical Center, Hackensack, NJ, USA
| | - Helio Pedro
- Center for Genetic and Genomic Medicine, Hackensack University Medical Center, Hackensack Meridian School of Medicine, Hackensack, NJ, USA
| | - Eric Mittelmann
- Department of Neurology, Hereditary Neuropathy Foundation Center of Excellence, Neuroscience Institute, Hackensack University Medical Center, Hackensack Meridian School of Medicine, Hackensack, NJ, USA
| | - Florian P Thomas
- Department of Neurology, Hereditary Neuropathy Foundation Center of Excellence, Neuroscience Institute, Hackensack University Medical Center, Hackensack Meridian School of Medicine, Hackensack, NJ, USA
| | - Katherine R Chao
- Center for Mendelian Genomics, Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Chamindra G Konersman
- Department of Neurosciences, University of California, San Diego, San Diego, CA, USA
| | | | | | - Volker Straub
- John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Anne M Connolly
- Department of Paediatrics, Neurology Division, Nationwide Children's Hospital, Ohio State University, Columbus, OH, USA
| | - Ulrike Schara
- Department of Paediatric Neurology, Center for Neuromuscular Disorders in Children and Adolescents, University Clinic Essen, University of Duisburg-Essen, Duisburg-Essen, Germany
| | - Andreas Roos
- Department of Paediatric Neurology, Center for Neuromuscular Disorders in Children and Adolescents, University Clinic Essen, University of Duisburg-Essen, Duisburg-Essen, Germany
| | - Mark Tarnopolsky
- Division of Neuromuscular & Neurometabolic Disorders, Department of Paediatrics, McMaster University, Hamilton Health Sciences Centre, Hamilton, Ontario, Canada
| | - Ahmet Höke
- Department of Neurology, Neuromuscular Division, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Robert H Brown
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Chia-Hsueh Lee
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Thorsten Hornemann
- Institute of Clinical Chemistry, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Teresa M Dunn
- Department of Biochemistry and Molecular Biology, Uniformed Services University of Health Sciences, Bethesda, MD, USA.
| | - Carsten G Bönnemann
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
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16
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Kicking off sphingolipid biosynthesis: structures of the serine palmitoyltransferase complex. Nat Struct Mol Biol 2021; 28:229-231. [PMID: 33558763 DOI: 10.1038/s41594-021-00562-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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17
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Alsiyabi A, Solis AG, Cahoon EB, Saha R. Dissecting the regulatory roles of ORM proteins in the sphingolipid pathway of plants. PLoS Comput Biol 2021; 17:e1008284. [PMID: 33507896 PMCID: PMC7872301 DOI: 10.1371/journal.pcbi.1008284] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 02/09/2021] [Accepted: 12/14/2020] [Indexed: 01/05/2023] Open
Abstract
Sphingolipids are a vital component of plant cellular endomembranes and carry out multiple functional and regulatory roles. Different sphingolipid species confer rigidity to the membrane structure, facilitate trafficking of secretory proteins, and initiate programmed cell death. Although the regulation of the sphingolipid pathway is yet to be uncovered, increasing evidence has pointed to orosomucoid proteins (ORMs) playing a major regulatory role and potentially interacting with a number of components in the pathway, including both enzymes and sphingolipids. However, experimental exploration of new regulatory interactions is time consuming and often infeasible. In this work, a computational approach was taken to address this challenge. A metabolic network of the sphingolipid pathway in plants was reconstructed. The steady-state rates of reactions in the network were then determined through measurements of growth and cellular composition of the different sphingolipids in Arabidopsis seedlings. The Ensemble modeling framework was modified to accurately account for activation mechanisms and subsequently used to generate sets of kinetic parameters that converge to the measured steady-state fluxes in a thermodynamically consistent manner. In addition, the framework was appended with an additional module to automate screening the parameters and to output models consistent with previously reported network responses to different perturbations. By analyzing the network's response in the presence of different combinations of regulatory mechanisms, the model captured the experimentally observed repressive effect of ORMs on serine palmitoyltransferase (SPT). Furthermore, predictions point to a second regulatory role of ORM proteins, namely as an activator of class II (or LOH1 and LOH3) ceramide synthases. This activating role was found to be modulated by the concentration of free ceramides, where an accumulation of these sphingolipid species dampened the activating effect of ORMs on ceramide synthase. The predictions pave the way for future guided experiments and have implications in engineering crops with higher biotic stress tolerance.
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Affiliation(s)
- Adil Alsiyabi
- Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
| | - Ariadna Gonzalez Solis
- Center for Plant Science Innovation & Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
| | - Edgar B. Cahoon
- Center for Plant Science Innovation & Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
| | - Rajib Saha
- Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
- Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
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18
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Gonzalez-Solis A, Han G, Gan L, Li Y, Markham JE, Cahoon RE, Dunn TM, Cahoon EB. Unregulated Sphingolipid Biosynthesis in Gene-Edited Arabidopsis ORM Mutants Results in Nonviable Seeds with Strongly Reduced Oil Content. THE PLANT CELL 2020; 32:2474-2490. [PMID: 32527862 PMCID: PMC7401009 DOI: 10.1105/tpc.20.00015] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 05/21/2020] [Accepted: 06/08/2020] [Indexed: 05/03/2023]
Abstract
Orosomucoid-like proteins (ORMs) interact with serine palmitoyltransferase (SPT) to negatively regulate sphingolipid biosynthesis, a reversible process critical for balancing the intracellular sphingolipid levels needed for growth and programmed cell death. Here, we show that ORM1 and ORM2 are essential for life cycle completion in Arabidopsis (Arabidopsis thaliana). Seeds from orm1 -/- orm2 -/- mutants, generated by crossing CRISPR/Cas9 knockout mutants for each gene, accumulated high levels of ceramide, indicative of unregulated sphingolipid biosynthesis. orm1 -/- orm2 -/- seeds were nonviable, displayed aberrant embryo development, and had >80% reduced oil content versus wild-type seeds. This phenotype was mimicked in Arabidopsis seeds expressing the SPT subunit LCB1 lacking its first transmembrane domain, which is critical for ORM-mediated regulation of SPT. We identified a mutant for ORM1 lacking one amino acid (Met-51) near its second transmembrane domain that retained its membrane topology. Expressing this allele in the orm2 background yielded plants that did not advance beyond the seedling stage, hyperaccumulated ceramides, and showed altered organellar structures and increased senescence- and pathogenesis-related gene expression. These seedlings also showed upregulated expression of genes for sphingolipid catabolic enzymes, pointing to additional mechanisms for maintaining sphingolipid homeostasis. ORM1 lacking Met-51 had strongly impaired interactions with LCB1 in a yeast (Saccharomyces cerevisiae) model, providing structural clues about regulatory interactions between ORM and SPT.
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Affiliation(s)
- Ariadna Gonzalez-Solis
- Center for Plant Science Innovation and Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588
| | - Gongshe Han
- Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814
| | - Lu Gan
- Center for Plant Science Innovation and Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588
| | - Yunfeng Li
- Center for Plant Science Innovation and Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588
| | - Jennifer E Markham
- Center for Plant Science Innovation and Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588
| | - Rebecca E Cahoon
- Center for Plant Science Innovation and Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588
| | - Teresa M Dunn
- Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814
| | - Edgar B Cahoon
- Center for Plant Science Innovation and Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588
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19
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Lee H, Fenske RJ, Akcan T, Domask E, Davis DB, Kimple ME, Engin F. Differential Expression of Ormdl Genes in the Islets of Mice and Humans with Obesity. iScience 2020; 23:101324. [PMID: 32659722 PMCID: PMC7358727 DOI: 10.1016/j.isci.2020.101324] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Revised: 05/05/2020] [Accepted: 06/25/2020] [Indexed: 12/28/2022] Open
Abstract
The orosomucoid-like (Ormdl) proteins play a critical role in sphingolipid homeostasis, inflammation, and ER stress, all of which are associated with obesity and βcell dysfunction. However, their roles in β cells and obesity remain unknown. Here, we show that islets from overweight/obese human donors displayed marginally reduced ORMDL1-2 expression, whereas ORMDL3 expression was significantly downregulated compared with islets from lean donors. In contrast, Ormdl3 was substantially upregulated in the islets of leptin-deficient obese (ob/ob) mice compared with lean mice. Treatment of ob/ob mice and their islets with leptin markedly reduced islet Ormld3 expression. Ormdl3 knockdown in a β cell line induced expression of pro-apoptotic markers, which was rescued by ceramide synthase inhibitor fumonisin B1. Our results reveal differential expression of Ormdl3 in the islets of a mouse model and humans with obesity, highlight the potential effect of leptin in this differential regulation, and suggest a role for Ormdl3 in β cell apoptosis. Islets of overweight/obese human donors display markedly reduced ORMDL3 expression Ormdl3 expression was significantly upregulated in the islets of ob/ob mice Leptin treatment markedly reduced Ormld3 expression in the islets of ob/ob mice Fumonisin B1 restores increased apoptotic marker levels induced by Ormdl3 silencing
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Affiliation(s)
- Hugo Lee
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, School of Medicine and Public Health, WI 53706, USA
| | - Rachel J Fenske
- Interdepartmental Graduate Program in Nutritional Sciences, Madison, WI 53706, USA; Department of Medicine, Division of Endocrinology, Diabetes & Metabolism, University of Wisconsin-Madison, School of Medicine and Public Health, WI 53705, USA; William S. Middleton Memorial Veterans Hospital, Madison, WI 53705, USA
| | - Tugce Akcan
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, School of Medicine and Public Health, WI 53706, USA
| | - Elliot Domask
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, School of Medicine and Public Health, WI 53706, USA
| | - Dawn B Davis
- Department of Medicine, Division of Endocrinology, Diabetes & Metabolism, University of Wisconsin-Madison, School of Medicine and Public Health, WI 53705, USA; William S. Middleton Memorial Veterans Hospital, Madison, WI 53705, USA
| | - Michelle E Kimple
- Interdepartmental Graduate Program in Nutritional Sciences, Madison, WI 53706, USA; Department of Medicine, Division of Endocrinology, Diabetes & Metabolism, University of Wisconsin-Madison, School of Medicine and Public Health, WI 53705, USA; William S. Middleton Memorial Veterans Hospital, Madison, WI 53705, USA; Department of Cell and Regenerative Biology, Madison, WI 53705, USA; Department of Academic Affairs, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Feyza Engin
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, School of Medicine and Public Health, WI 53706, USA; Department of Medicine, Division of Endocrinology, Diabetes & Metabolism, University of Wisconsin-Madison, School of Medicine and Public Health, WI 53705, USA.
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20
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Subunit composition of the mammalian serine-palmitoyltransferase defines the spectrum of straight and methyl-branched long-chain bases. Proc Natl Acad Sci U S A 2020; 117:15591-15598. [PMID: 32576697 DOI: 10.1073/pnas.2002391117] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Sphingolipids (SLs) are chemically diverse lipids that have important structural and signaling functions within mammalian cells. SLs are commonly defined by the presence of a long-chain base (LCB) that is normally formed by the conjugation of l-serine and palmitoyl-CoA. This pyridoxal 5-phosphate (PLP)-dependent reaction is mediated by the enzyme serine-palmitoyltransferase (SPT). However, SPT can also metabolize other acyl-CoAs, in the range of C14 to C18, forming a variety of LCBs that differ by structure and function. Mammalian SPT consists of three core subunits: SPTLC1, SPTLC2, and SPTLC3. Whereas SPTLC1 and SPTLC2 are ubiquitously expressed, SPTLC3 expression is restricted to certain tissues only. The influence of the individual subunits on enzyme activity is not clear. Using cell models deficient in SPTLC1, SPTLC2, and SPTLC3, we investigated the role of each subunit on enzyme activity and the LCB product spectrum. We showed that SPTLC1 is essential for activity, whereas SPTLC2 and SPTLC3 are partly redundant but differ in their enzymatic properties. SPTLC1 in combination with SPTLC2 specifically formed C18, C19, and C20 LCBs while the combination of SPTLC1 and SPTLC3 yielded a broader product spectrum. We identified anteiso-branched-C18 SO (meC18SO) as the primary product of the SPTLC3 reaction. The meC18SO was synthesized from anteiso-methyl-palmitate, in turn synthesized from a precursor metabolite generated in the isoleucine catabolic pathway. The meC18SO is metabolized to ceramides and complex SLs and is a constituent of human low- and high-density lipoproteins.
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21
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Clarke BA, Majumder S, Zhu H, Lee YT, Kono M, Li C, Khanna C, Blain H, Schwartz R, Huso VL, Byrnes C, Tuymetova G, Dunn TM, Allende ML, Proia RL. The Ormdl genes regulate the sphingolipid synthesis pathway to ensure proper myelination and neurologic function in mice. eLife 2019; 8:51067. [PMID: 31880535 PMCID: PMC6934382 DOI: 10.7554/elife.51067] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 12/09/2019] [Indexed: 12/23/2022] Open
Abstract
Sphingolipids are membrane and bioactive lipids that are required for many aspects of normal mammalian development and physiology. However, the importance of the regulatory mechanisms that control sphingolipid levels in these processes is not well understood. The mammalian ORMDL proteins (ORMDL1, 2 and 3) mediate feedback inhibition of the de novo synthesis pathway of sphingolipids by inhibiting serine palmitoyl transferase in response to elevated ceramide levels. To understand the function of ORMDL proteins in vivo, we studied mouse knockouts (KOs) of the Ormdl genes. We found that Ormdl1 and Ormdl3 function redundantly to suppress the levels of bioactive sphingolipid metabolites during myelination of the sciatic nerve. Without proper ORMDL-mediated regulation of sphingolipid synthesis, severe dysmyelination results. Our data indicate that the Ormdls function to restrain sphingolipid metabolism in order to limit levels of dangerous metabolic intermediates that can interfere with essential physiological processes such as myelination.
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Affiliation(s)
- Benjamin A Clarke
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States
| | - Saurav Majumder
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States
| | - Hongling Zhu
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States
| | - Y Terry Lee
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States
| | - Mari Kono
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States
| | - Cuiling Li
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States
| | - Caroline Khanna
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States
| | - Hailey Blain
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States
| | - Ronit Schwartz
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States
| | - Vienna L Huso
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States
| | - Colleen Byrnes
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States
| | - Galina Tuymetova
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States
| | - Teresa M Dunn
- Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, United States
| | - Maria L Allende
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States
| | - Richard L Proia
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States
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22
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Su WC, Lin YH, Pagac M, Wang CW. Seipin negatively regulates sphingolipid production at the ER-LD contact site. J Cell Biol 2019; 218:3663-3680. [PMID: 31594806 PMCID: PMC6829658 DOI: 10.1083/jcb.201902072] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 06/23/2019] [Accepted: 08/08/2019] [Indexed: 01/06/2023] Open
Abstract
Su et al. show that seipin negatively regulates the production of sphingoid intermediates by binding the enzymes serine palmitoyltransferase and fatty acid elongase at discrete regions of the ER in close vicinity to lipid droplets, thereby mediating the synthesis of two major building blocks for sphingolipids. Seipin is known for its critical role in controlling lipid droplet (LD) assembly at the LD-forming subdomain of the endoplasmic reticulum (ER). Here, we identified a new function of seipin as a negative regulator for sphingolipid production. We show that yeast cells lacking seipin displayed altered sensitivity to sphingolipid inhibitors, accumulated sphingoid precursors and intermediates, and increased serine palmitoyltransferase (SPT) and fatty acid (FA) elongase activities. Seipin associated with SPT and FA elongase, and the interaction was reduced by inhibitors for sphingolipid synthesis in a concentration-dependent manner. We further show that the interactions of seipin with SPT and FA elongase occurred at ER–LD contacts and were likely regulated differentially. Further evidence indicated that LD biogenesis was intact when SPT activity was blocked, whereas excess sphingoid intermediates may affect LD morphology. Expression of human seipin rescued the altered sphingolipids in yeast seipin mutants, suggesting that the negative regulation of sphingolipid synthesis by seipin is likely an evolutionarily conserved process.
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Affiliation(s)
- Wei-Cheng Su
- Institute of Plant and Microbial Biology, Academia Sinica, Nangang, Taipei, Taiwan
| | - Yi-Hsiu Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Nangang, Taipei, Taiwan
| | - Martin Pagac
- Institute of Plant and Microbial Biology, Academia Sinica, Nangang, Taipei, Taiwan
| | - Chao-Wen Wang
- Institute of Plant and Microbial Biology, Academia Sinica, Nangang, Taipei, Taiwan
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23
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Zahumensky J, Malinsky J. Role of MCC/Eisosome in Fungal Lipid Homeostasis. Biomolecules 2019; 9:E305. [PMID: 31349700 PMCID: PMC6723945 DOI: 10.3390/biom9080305] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 07/19/2019] [Accepted: 07/22/2019] [Indexed: 12/11/2022] Open
Abstract
One of the best characterized fungal membrane microdomains is the MCC/eisosome. The MCC (membrane compartment of Can1) is an evolutionarily conserved ergosterol-rich plasma membrane domain. It is stabilized on its cytosolic face by the eisosome, a hemitubular protein complex composed of Bin/Amphiphysin/Rvs (BAR) domain-containing Pil1 and Lsp1. These two proteins bind directly to phosphatidylinositol 4,5-bisphosphate and promote the typical furrow-like shape of the microdomain, with highly curved edges and bottom. While some proteins display stable localization in the MCC/eisosome, others enter or leave it under particular conditions, such as misbalance in membrane lipid composition, changes in membrane tension, or availability of specific nutrients. These findings reveal that the MCC/eisosome, a plasma membrane microdomain with distinct morphology and lipid composition, acts as a multifaceted regulator of various cellular processes including metabolic pathways, cellular morphogenesis, signalling cascades, and mRNA decay. In this minireview, we focus on the MCC/eisosome's proposed role in the regulation of lipid metabolism. While the molecular mechanisms of the MCC/eisosome function are not completely understood, the idea of intracellular processes being regulated at the plasma membrane, the foremost barrier exposed to environmental challenges, is truly exciting.
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Affiliation(s)
- Jakub Zahumensky
- Department of Microscopy, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, 14220 Prague, Czech Republic
| | - Jan Malinsky
- Department of Microscopy, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, 14220 Prague, Czech Republic.
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24
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Davis DL, Gable K, Suemitsu J, Dunn TM, Wattenberg BW. The ORMDL/Orm-serine palmitoyltransferase (SPT) complex is directly regulated by ceramide: Reconstitution of SPT regulation in isolated membranes. J Biol Chem 2019; 294:5146-5156. [PMID: 30700557 DOI: 10.1074/jbc.ra118.007291] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 01/25/2019] [Indexed: 01/15/2023] Open
Abstract
Sphingolipids compose a lipid family critical for membrane structure as well as intra- and intercellular signaling. De novo sphingolipid biosynthesis is initiated by the enzyme serine palmitoyltransferase (SPT), which resides in the endoplasmic reticulum (ER) membrane. In both yeast and mammalian species, SPT activity is homeostatically regulated through small ER membrane proteins, the Orms in yeast and the ORMDLs in mammalian cells. These proteins form stable complexes with SPT. In yeast, the homeostatic regulation of SPT relies, at least in part, on phosphorylation of the Orms. However, this does not appear to be the case for the mammalian ORMDLs. Here, we accomplished a cell-free reconstitution of the sphingolipid regulation of the ORMDL-SPT complex to probe the underlying regulatory mechanism. Sphingolipid and ORMDL-dependent regulation of SPT was demonstrated in isolated membranes, essentially free of cytosol. This suggests that this regulation does not require soluble cytosolic proteins or small molecules such as ATP. We found that this system is particularly responsive to the pro-apoptotic sphingolipid ceramide and that this response is strictly stereospecific, indicating that ceramide regulates the ORMDL-SPT complex via a specific binding interaction. Yeast membranes harboring the Orm-SPT system also directly responded to sphingolipid, suggesting that yeast cells have, in addition to Orm phosphorylation, an additional Orm-dependent SPT regulatory mechanism. Our results indicate that ORMDL/Orm-mediated regulation of SPT involves a direct interaction of sphingolipid with the membrane-bound components of the SPT-regulatory apparatus.
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Affiliation(s)
- Deanna L Davis
- From the Department of Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine, Richmond, Virginia 23298
| | - Kenneth Gable
- the Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, and
| | - John Suemitsu
- From the Department of Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine, Richmond, Virginia 23298
| | - Teresa M Dunn
- the Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, and
| | - Binks W Wattenberg
- From the Department of Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine, Richmond, Virginia 23298, .,the James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, Kentucky 40202
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