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Diaz Escarcega R, Murambadoro K, Valencia R, Moruno-Manchon JF, Furr Stimming EE, Jung SY, Tsvetkov AS. Sphingosine kinase 2 regulates protein ubiquitination networks in neurons. Mol Cell Neurosci 2024; 130:103948. [PMID: 38909878 DOI: 10.1016/j.mcn.2024.103948] [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: 01/15/2024] [Revised: 05/31/2024] [Accepted: 06/17/2024] [Indexed: 06/25/2024] Open
Abstract
Two sphingosine kinase isoforms, sphingosine kinase 1 (SPHK1) and sphingosine kinase 2 (SPHK2), synthesize the lipid sphingosine-1-phosphate (S1P) by phosphorylating sphingosine. SPHK1 is a cytoplasmic kinase, and SPHK2 is localized to the nucleus and other organelles. In the cytoplasm, the SPHK1/S1P pathway modulates autophagy and protein ubiquitination, among other processes. In the nucleus, the SPHK2/S1P pathway regulates transcription. Here, we hypothesized that the SPHK2/S1P pathway governs protein ubiquitination in neurons. We found that ectopic expression of SPHK2 increases ubiquitinated substrate levels in cultured neurons and pharmacologically inhibiting SPHK2 decreases protein ubiquitination. With mass spectrometry, we discovered that inhibiting SPHK2 affects lipid and synaptic protein networks as well as a ubiquitin-dependent protein network. Several ubiquitin-conjugating and hydrolyzing proteins, such as the E3 ubiquitin-protein ligases HUWE1 and TRIP12, the E2 ubiquitin-conjugating enzyme UBE2Z, and the ubiquitin-specific proteases USP15 and USP30, were downregulated by SPHK2 inhibition. Using RNA sequencing, we found that inhibiting SPHK2 altered lipid and neuron-specific gene networks, among others. Genes that encode the corresponding proteins from the ubiquitin-dependent protein network that we discovered with mass spectrometry were not affected by inhibiting SPHK2, indicating that the SPHK2/S1P pathway regulates ubiquitination at the protein level. We also show that both SPHK2 and HUWE1 were upregulated in the striatum of a mouse model of Huntington's disease, the BACHD mice, indicating that our findings are relevant to neurodegenerative diseases. Our results identify SPHK2/S1P as a novel regulator of protein ubiquitination networks in neurons and provide a new target for developing therapies for neurodegenerative diseases.
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Affiliation(s)
- Rocio Diaz Escarcega
- Department of Neurology, University of Texas McGovern Medical School, Houston, TX 77030, United States of America
| | - Karen Murambadoro
- Department of Neurology, University of Texas McGovern Medical School, Houston, TX 77030, United States of America
| | - Ricardo Valencia
- Department of Neurology, University of Texas McGovern Medical School, Houston, TX 77030, United States of America
| | - Jose Felix Moruno-Manchon
- Department of Neurology, University of Texas McGovern Medical School, Houston, TX 77030, United States of America
| | - Erin E Furr Stimming
- Department of Neurology, University of Texas McGovern Medical School, Houston, TX 77030, United States of America
| | - Sung Yun Jung
- Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX 77030, United States of America.
| | - Andrey S Tsvetkov
- Department of Neurology, University of Texas McGovern Medical School, Houston, TX 77030, United States of America; The University of Texas Graduate School of Biomedical Sciences, Houston, TX 77030, United States of America; UTHealth Consortium on Aging, the University of Texas McGovern Medical School, Houston, TX 77030, United States of America.
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Morishige JI, Yoshioka K, Nakata H, Ishimaru K, Nagata N, Tanaka T, Takuwa Y, Ando H. Sphingosine kinase 1 is involved in triglyceride breakdown by maintaining lysosomal integrity in brown adipocytes. J Lipid Res 2023; 64:100450. [PMID: 37751791 PMCID: PMC10630120 DOI: 10.1016/j.jlr.2023.100450] [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: 01/30/2023] [Revised: 08/30/2023] [Accepted: 09/15/2023] [Indexed: 09/28/2023] Open
Abstract
Sphingosine 1-phosphate (S1P) has been implicated in brown adipose tissue (BAT) formation and energy consumption; however, the mechanistic role of sphingolipids, including S1P, in BAT remains unclear. Here, we showed that, in mice, BAT activation by cold exposure upregulated mRNA and protein expression of the S1P-synthesizing enzyme sphingosine kinase 1 (SphK1) and S1P production in BAT. Treatment of wild-type brown adipocytes with exogenous S1P or S1P receptor subtype-selective agonists stimulated triglyceride (TG) breakdown only marginally, compared with noradrenaline. However, genetic deletion of Sphk1 resulted in hypothermia and diminished body weight loss upon cold exposure, suggesting that SphK1 is involved in thermogenesis through mechanisms different from receptor-mediated, extracellular action of S1P. In BAT of wild-type mice, SphK1 was localized largely in the lysosomes of brown adipocytes. In the brown adipocytes of Sphk1-/- mice, the number of lysosomes was reduced and lysosomal function, including proteolytic activity, acid esterase activity, and motility, was impaired. Concordantly, nuclear translocation of transcription factor EB, a master transcriptional regulator of lysosome biogenesis, was reduced, leading to decreased mRNA expression of the lysosome-related genes in Sphk1-/- BAT. Moreover, BAT of Sphk1-/- mice showed greater TG accumulation with dominant larger lipid droplets in brown adipocytes. Inhibition of lysosomes with chloroquine resulted in a less extent of triglyceride accumulation in Sphk1-/- brown adipocytes compared with wild-type brown adipocytes, suggesting a reduced lysosome-mediated TG breakdown in Sphk1-/- mice. Our results indicate a novel role of SphK1 in lysosomal integrity, which is required for TG breakdown and thermogenesis in BAT.
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Affiliation(s)
- Jun-Ichi Morishige
- Department of Cellular and Molecular Function Analysis, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan.
| | - Kazuaki Yoshioka
- Department of Physiology, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
| | - Hiroki Nakata
- Department of Clinical Engineering, Faculty of Health Sciences, Komatsu University, Komatsu, Japan
| | - Kazuhiro Ishimaru
- Department of Physiology, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
| | - Naoto Nagata
- Department of Cellular and Molecular Function Analysis, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
| | - Tamotsu Tanaka
- Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima, Japan
| | - Yoh Takuwa
- Department of Physiology, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan.
| | - Hitoshi Ando
- Department of Cellular and Molecular Function Analysis, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan.
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Jiang ZJ, Gong LW. The SphK1/S1P Axis Regulates Synaptic Vesicle Endocytosis via TRPC5 Channels. J Neurosci 2023; 43:3807-3824. [PMID: 37185099 PMCID: PMC10217994 DOI: 10.1523/jneurosci.1494-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 04/13/2023] [Accepted: 04/17/2023] [Indexed: 05/17/2023] Open
Abstract
Sphingosine-1-phosphate (S1P), a bioactive sphingolipid concentrated in the brain, is essential for normal brain functions, such as learning and memory and feeding behaviors. Sphingosine kinase 1 (SphK1), the primary kinase responsible for S1P production in the brain, is abundant within presynaptic terminals, indicating a potential role of the SphK1/S1P axis in presynaptic physiology. Altered S1P levels have been highlighted in many neurologic diseases with endocytic malfunctions. However, it remains unknown whether the SphK1/S1P axis may regulate synaptic vesicle endocytosis in neurons. The present study evaluates potential functions of the SphK1/S1P axis in synaptic vesicle endocytosis by determining effects of a dominant negative catalytically inactive SphK1. Our data for the first time identify a critical role of the SphK1/S1P axis in endocytosis in both neuroendocrine chromaffin cells and neurons from mice of both sexes. Furthermore, our Ca2+ imaging data indicate that the SphK1/S1P axis may be important for presynaptic Ca2+ increases during prolonged stimulations by regulating the Ca2+ permeable TRPC5 channels, which per se regulate synaptic vesicle endocytosis. Collectively, our data point out a critical role of the regulation of TRPC5 by the SphK1/S1P axis in synaptic vesicle endocytosis.SIGNIFICANCE STATEMENT Sphingosine kinase 1 (SphK1), the primary kinase responsible for brain sphingosine-1-phosphate (S1P) production, is abundant within presynaptic terminals. Altered SphK1/S1P metabolisms has been highlighted in many neurologic disorders with defective synaptic vesicle endocytosis. However, whether the SphK1/S1P axis may regulate synaptic vesicle endocytosis is unknown. Here, we identify that the SphK1/S1P axis regulates the kinetics of synaptic vesicle endocytosis in neurons, in addition to controlling fission-pore duration during single vesicle endocytosis in neuroendocrine chromaffin cells. The regulation of the SphK1/S1P axis in synaptic vesicle endocytosis is specific since it has a distinguished signaling pathway, which involves regulation of Ca2+ influx via TRPC5 channels. This discovery may provide novel mechanistic implications for the SphK1/S1P axis in brain functions under physiological and pathologic conditions.
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Affiliation(s)
- Zhong-Jiao Jiang
- Department of Biological Sciences, University of Illinois Chicago, Chicago, Illinois 60607
| | - Liang-Wei Gong
- Department of Biological Sciences, University of Illinois Chicago, Chicago, Illinois 60607
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Alizadeh J, Kavoosi M, Singh N, Lorzadeh S, Ravandi A, Kidane B, Ahmed N, Mraiche F, Mowat MR, Ghavami S. Regulation of Autophagy via Carbohydrate and Lipid Metabolism in Cancer. Cancers (Basel) 2023; 15:cancers15082195. [PMID: 37190124 DOI: 10.3390/cancers15082195] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 03/21/2023] [Accepted: 03/28/2023] [Indexed: 05/17/2023] Open
Abstract
Metabolic changes are an important component of tumor cell progression. Tumor cells adapt to environmental stresses via changes to carbohydrate and lipid metabolism. Autophagy, a physiological process in mammalian cells that digests damaged organelles and misfolded proteins via lysosomal degradation, is closely associated with metabolism in mammalian cells, acting as a meter of cellular ATP levels. In this review, we discuss the changes in glycolytic and lipid biosynthetic pathways in mammalian cells and their impact on carcinogenesis via the autophagy pathway. In addition, we discuss the impact of these metabolic pathways on autophagy in lung cancer.
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Affiliation(s)
- Javad Alizadeh
- Department of Human Anatomy and Cell Science, College of Medicine, University of Manitoba, Winnipeg, MB R3E 0V9, Canada
| | - Mahboubeh Kavoosi
- Department of Human Anatomy and Cell Science, College of Medicine, University of Manitoba, Winnipeg, MB R3E 0V9, Canada
| | - Navjit Singh
- Department of Human Anatomy and Cell Science, College of Medicine, University of Manitoba, Winnipeg, MB R3E 0V9, Canada
| | - Shahrokh Lorzadeh
- Department of Human Anatomy and Cell Science, College of Medicine, University of Manitoba, Winnipeg, MB R3E 0V9, Canada
| | - Amir Ravandi
- Department of Physiology and Pathophysiology, Rady Faculty of Health Sciences, Institute of Cardiovascular Sciences, Albrechtsen Research Centre, St. Boniface Hospital, Winnipeg, MB R2H 2A6, Canada
| | - Biniam Kidane
- Section of Thoracic Surgery, Department of Surgery, Health Sciences Centre, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3T 6C5, Canada
- CancerCare Manitoba Research Institute, Winnipeg, MB R3E 0V9, Canada
| | - Naseer Ahmed
- CancerCare Manitoba Research Institute, Winnipeg, MB R3E 0V9, Canada
- Department of Radiology, Section of Radiation Oncology, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Fatima Mraiche
- College of Pharmacy, QU Health, Qatar University, Doha 2713, Qatar
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Michael R Mowat
- CancerCare Manitoba Research Institute, Winnipeg, MB R3E 0V9, Canada
- Department of Biochemistry & Medical Genetics, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
| | - Saeid Ghavami
- Department of Human Anatomy and Cell Science, College of Medicine, University of Manitoba, Winnipeg, MB R3E 0V9, Canada
- Research Institute of Oncology and Hematology, Winnipeg, MB R3E 0V9, Canada
- Faculty of Medicine in Zabrze, Academia of Silesia, 41-800 Zabrze, Poland
- Biology of Breathing Theme, Children Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, MB R3E 3P5, Canada
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Zeng Y, Zhang W, Xue T, Zhang D, Lv M, Jiang Y. Sphk1-induced autophagy in microglia promotes neuronal injury following cerebral ischaemia-reperfusion. Eur J Neurosci 2022; 56:4287-4303. [PMID: 35766986 DOI: 10.1111/ejn.15749] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 06/20/2022] [Accepted: 06/24/2022] [Indexed: 12/16/2022]
Abstract
Microglial hyperactivation mediated by sphingosine kinase 1/sphingosine-1-phosphate (SphK1/S1P) signalling and the consequent inflammatory mediator production serve as the key drivers of cerebral ischaemia-reperfusion injury (CIRI). Although SphK1 reportedly controls autophagy and microglial activation, it remains uncertain as to whether SphK1 is similarly capable of regulating damage mediated by CIRI-activated microglia. In the current study, we adopted both in vitro oxygen-glucose deprivation reperfusion (OGDR) models and in vivo rat models of focal CIRI to ascertain this possibility. It was found that CIRI upregulated SphK1 and induced autophagy in microglia, while inhibiting these changes significantly impaired to prevented neuronal apoptosis. Results of mechanistic investigation revealed that SphK1 promoted autophagy via the tumour necrosis factor receptor associated factor 2 (TRAF2) pathway. Altogether, our findings unfolded to reveal a novel mechanism, whereby SphK1-induced autophagy in microglia contributed to the pathogenesis of CIRI, potentially highlighting novel avenues for future therapeutic intervention in ischaemic stroke patients.
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Affiliation(s)
- Yuanyuan Zeng
- Department of Neurology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Wei Zhang
- Department of Neurology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Tengteng Xue
- Department of Neurology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Dayong Zhang
- Department of New Media and Arts, Harbin Institute of Technology, Harbin, China
| | - Manhua Lv
- Department of Neurology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Yongjia Jiang
- Department of Neurology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
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Loss of E-Cadherin Leads to Druggable Vulnerabilities in Sphingolipid Metabolism and Vesicle Trafficking. Cancers (Basel) 2021; 14:cancers14010102. [PMID: 35008266 PMCID: PMC8749886 DOI: 10.3390/cancers14010102] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 12/23/2021] [Indexed: 01/02/2023] Open
Abstract
Simple Summary Germline loss of the CDH1 gene is the primary genetic basis for hereditary diffuse gastric cancer, a disease resulting in elevated risk of both diffuse gastric cancer and lobular breast cancer. Current preventative treatment consists of prophylactic total gastrectomy, a therapy with several associated long-term morbidities. To address the lack of targeted molecular therapies for hereditary diffuse gastric cancer, we have utilized a synthetic lethal approach to identify candidate compounds that can specifically kill CDH1-null cells. Inhibitors of sphingolipid metabolism and vesicle trafficking pathways were identified as promising candidate compounds in a cell line model of CDH1 loss, then further validated in murine-derived organoid models of hereditary diffuse gastric cancer. With further research, these findings may lead to the development of novel chemoprevention strategies for the treatment of hereditary diffuse gastric cancer. Abstract Germline inactivating variants of CDH1 are causative of hereditary diffuse gastric cancer (HDGC), a cancer syndrome characterized by an increased risk of both diffuse gastric cancer and lobular breast cancer. Because loss of function mutations are difficult to target therapeutically, we have taken a synthetic lethal approach to identify targetable vulnerabilities in CDH1-null cells. We have previously observed that CDH1-null MCF10A cells exhibit a reduced rate of endocytosis relative to wildtype MCF10A cells. To determine whether this deficiency is associated with wider vulnerabilities in vesicle trafficking, we screened isogenic MCF10A cell lines with known inhibitors of autophagy, endocytosis, and sphingolipid metabolism. Relative to wildtype MCF10A cells, CDH1−/− MCF10A cells showed significantly greater sensitivity to several drugs targeting these processes, including the autophagy inhibitor chloroquine, the endocytosis inhibitors chlorpromazine and PP1, and the sphingosine kinase 1 inhibitor PF-543. Synthetic lethality was confirmed in both gastric and mammary organoid models of CDH1 loss, derived from CD44-Cre/Cdh1fl/fl/tdTomato mice. Collectively, these results suggest that both sphingolipid metabolism and vesicle trafficking represent previously unrecognised druggable vulnerabilities in CDH1-null cells and may lead to the development of new therapies for HDGC.
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Cui M, Göbel V, Zhang H. Uncovering the 'sphinx' of sphingosine 1-phosphate signalling: from cellular events to organ morphogenesis. Biol Rev Camb Philos Soc 2021; 97:251-272. [PMID: 34585505 PMCID: PMC9292677 DOI: 10.1111/brv.12798] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 09/11/2021] [Accepted: 09/16/2021] [Indexed: 11/02/2022]
Abstract
Sphingosine 1-phosphate (S1P) is a bioactive sphingolipid metabolite, functioning as a signalling molecule in diverse cellular processes. Over the past few decades, studies of S1P signalling have revealed that the physiological activity of S1P largely depends on S1P metabolizing enzymes, transporters and receptors on the plasma membrane, as well as on the intracellular proteins that S1P binds directly to. In addition to its roles in cancer signalling, immunity and inflammation, a large body of evidence has identified a close link of S1P signalling with organ morphogenesis. Here we discuss the vital role of S1P signalling in orchestrating various cellular events during organ morphogenesis through analysing each component along the extracellular and intracellular S1P signalling axes. For each component, we review advances in our understanding of S1P signalling and function from the upstream regulators to the downstream effectors and from cellular behaviours to tissue organization, primarily in the context of morphogenetic mechanisms. S1P-mediated vesicular trafficking is also discussed as a function independent of its signalling function. A picture emerges that reveals a multifaceted role of S1P-dependent pathways in the development and maintenance of organ structure and function.
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Affiliation(s)
- Mengqiao Cui
- Centre of Reproduction, Development and Aging, Faculty of Health Sciences, University of Macau, Taipa, Macau SAR, 999078, China
| | - Verena Göbel
- Mucosal Immunology and Biology Research Center, Department of Pediatrics, Massachusetts General Hospital and Harvard Medical School, Boston, MA, 02114, U.S.A
| | - Hongjie Zhang
- Centre of Reproduction, Development and Aging, Faculty of Health Sciences, University of Macau, Taipa, Macau SAR, 999078, China.,MoE Frontiers Science Center for Precision Oncology, University of Macau, Taipa, Macau SAR, 999078, China
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Patrizz AN, Moruno-Manchon JF, O’Keefe LM, Doran SJ, Patel AR, Venna VR, Tsvetkov AS, Li J, McCullough LD. Sex-Specific Differences in Autophagic Responses to Experimental Ischemic Stroke. Cells 2021; 10:cells10071825. [PMID: 34359998 PMCID: PMC8304137 DOI: 10.3390/cells10071825] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 07/14/2021] [Accepted: 07/16/2021] [Indexed: 12/25/2022] Open
Abstract
Ischemic stroke triggers a series of complex pathophysiological processes including autophagy. Differential activation of autophagy occurs in neurons derived from males versus females after stressors such as nutrient deprivation. Whether autophagy displays sexual dimorphism after ischemic stroke is unknown. We used a cerebral ischemia mouse model (middle cerebral artery occlusion, MCAO) to evaluate the effects of inhibiting autophagy in ischemic brain pathology. We observed that inhibiting autophagy reduced infarct volume in males and ovariectomized females. However, autophagy inhibition enhanced infarct size in females and in ovariectomized females supplemented with estrogen compared to control mice. We also observed that males had increased levels of Beclin1 and LC3 and decreased levels of pULK1 and p62 at 24 h, while females had decreased levels of Beclin1 and increased levels of ATG7. Furthermore, the levels of autophagy markers were increased under basal conditions and after oxygen and glucose deprivation in male neurons compared with female neurons in vitro. E2 supplementation significantly inhibited autophagy only in male neurons, and was beneficial for cell survival only in female neurons. This study shows that autophagy in the ischemic brain differs between the sexes, and that autophagy regulators have different effects in a sex-dependent manner in neurons.
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Affiliation(s)
- Anthony N. Patrizz
- Department of Neurology, McGovern Medical School at the University of Texas Health Science Center at Houston, 6431 Fannin Street, Houston, TX 77030, USA; (A.N.P.); (J.F.M.-M.); (V.R.V.); (A.S.T.); (J.L.)
| | - Jose F. Moruno-Manchon
- Department of Neurology, McGovern Medical School at the University of Texas Health Science Center at Houston, 6431 Fannin Street, Houston, TX 77030, USA; (A.N.P.); (J.F.M.-M.); (V.R.V.); (A.S.T.); (J.L.)
| | - Lena M. O’Keefe
- Department of Neurology, Beth Israel Deaconess Hospital, 330 Brookline Avenue, Boston, MA 02215, USA;
| | - Sarah J. Doran
- Department of Neuroscience, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030, USA; (S.J.D.); (A.R.P.)
| | - Anita R. Patel
- Department of Neuroscience, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030, USA; (S.J.D.); (A.R.P.)
| | - Venugopal R. Venna
- Department of Neurology, McGovern Medical School at the University of Texas Health Science Center at Houston, 6431 Fannin Street, Houston, TX 77030, USA; (A.N.P.); (J.F.M.-M.); (V.R.V.); (A.S.T.); (J.L.)
| | - Andrey S. Tsvetkov
- Department of Neurology, McGovern Medical School at the University of Texas Health Science Center at Houston, 6431 Fannin Street, Houston, TX 77030, USA; (A.N.P.); (J.F.M.-M.); (V.R.V.); (A.S.T.); (J.L.)
| | - Jun Li
- Department of Neurology, McGovern Medical School at the University of Texas Health Science Center at Houston, 6431 Fannin Street, Houston, TX 77030, USA; (A.N.P.); (J.F.M.-M.); (V.R.V.); (A.S.T.); (J.L.)
| | - Louise D. McCullough
- Department of Neurology, McGovern Medical School at the University of Texas Health Science Center at Houston, 6431 Fannin Street, Houston, TX 77030, USA; (A.N.P.); (J.F.M.-M.); (V.R.V.); (A.S.T.); (J.L.)
- Correspondence:
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9
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Chua JP, De Calbiac H, Kabashi E, Barmada SJ. Autophagy and ALS: mechanistic insights and therapeutic implications. Autophagy 2021; 18:254-282. [PMID: 34057020 PMCID: PMC8942428 DOI: 10.1080/15548627.2021.1926656] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Mechanisms of protein homeostasis are crucial for overseeing the clearance of misfolded and toxic proteins over the lifetime of an organism, thereby ensuring the health of neurons and other cells of the central nervous system. The highly conserved pathway of autophagy is particularly necessary for preventing and counteracting pathogenic insults that may lead to neurodegeneration. In line with this, mutations in genes that encode essential autophagy factors result in impaired autophagy and lead to neurodegenerative conditions such as amyotrophic lateral sclerosis (ALS). However, the mechanistic details underlying the neuroprotective role of autophagy, neuronal resistance to autophagy induction, and the neuron-specific effects of autophagy-impairing mutations remain incompletely defined. Further, the manner and extent to which non-cell autonomous effects of autophagy dysfunction contribute to ALS pathogenesis are not fully understood. Here, we review the current understanding of the interplay between autophagy and ALS pathogenesis by providing an overview of critical steps in the autophagy pathway, with special focus on pivotal factors impaired by ALS-causing mutations, their physiologic effects on autophagy in disease models, and the cell type-specific mechanisms regulating autophagy in non-neuronal cells which, when impaired, can contribute to neurodegeneration. This review thereby provides a framework not only to guide further investigations of neuronal autophagy but also to refine therapeutic strategies for ALS and related neurodegenerative diseases.Abbreviations: ALS: amyotrophic lateral sclerosis; Atg: autophagy-related; CHMP2B: charged multivesicular body protein 2B; DPR: dipeptide repeat; FTD: frontotemporal dementia; iPSC: induced pluripotent stem cell; LIR: LC3-interacting region; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MTOR: mechanistic target of rapamycin kinase; PINK1: PTEN induced kinase 1; RNP: ribonuclear protein; sALS: sporadic ALS; SPHK1: sphingosine kinase 1; TARDBP/TDP-43: TAR DNA binding protein; TBK1: TANK-binding kinase 1; TFEB: transcription factor EB; ULK: unc-51 like autophagy activating kinase; UPR: unfolded protein response; UPS: ubiquitin-proteasome system; VCP: valosin containing protein.
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Affiliation(s)
- Jason P Chua
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| | - Hortense De Calbiac
- Recherche translationnelle sur les maladies neurologiques, Institut Imagine, UMR-1163 INSERM et Université Paris Descartes, Hôpital Universitaire Necker-Enfants Malades, Paris, France
| | - Edor Kabashi
- Recherche translationnelle sur les maladies neurologiques, Institut Imagine, UMR-1163 INSERM et Université Paris Descartes, Hôpital Universitaire Necker-Enfants Malades, Paris, France
| | - Sami J Barmada
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
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10
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Wang C, Xu T, Lachance BB, Zhong X, Shen G, Xu T, Tang C, Jia X. Critical roles of sphingosine kinase 1 in the regulation of neuroinflammation and neuronal injury after spinal cord injury. J Neuroinflammation 2021; 18:50. [PMID: 33602274 PMCID: PMC7893778 DOI: 10.1186/s12974-021-02092-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 01/19/2021] [Indexed: 01/06/2023] Open
Abstract
Background The pathological process of traumatic spinal cord injury (SCI) involves excessive activation of microglia leading to the overproduction of proinflammatory cytokines and causing neuronal injury. Sphingosine kinase 1 (Sphk1), a key enzyme responsible for phosphorylating sphingosine into sphingosine-1-phosphate (S1P), plays an important role in mediating inflammation, cell proliferation, survival, and immunity. Methods We aim to investigate the mechanism and pathway of the Sphk1-mediated neuroinflammatory response in a rodent model of SCI. Sixty Sprague-Dawley rats were randomly assigned to sham surgery, SCI, or PF543 (a specific Sphk1 inhibitor) groups. Functional outcomes included blinded hindlimb locomotor rating and inclined plane test. Results We discovered that Sphk1 is upregulated in injured spinal cord tissue of rats after SCI and is associated with production of S1P and subsequent NF-κB p65 activation. PF543 attenuated p65 activation, reduced inflammatory response, and relieved neuronal damage, leading to improved functional recovery. Western blot analysis confirmed that expression of S1P receptor 3 (S1PR3) and phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK) are activated in microglia of SCI rats and mitigated by PF543. In vitro, we demonstrated that Bay11-7085 suppressed NF-κB p65 and inhibited amplification of the inflammation cascade by S1P, reducing the release of proinflammatory TNF-α. We further confirmed that phosphorylation of p38 MAPK and activation of NF-κB p65 is inhibited by PF543 and CAY10444. p38 MAPK phosphorylation and NF-κB p65 activation were enhanced by exogenous S1P and inhibited by the specific inhibitor SB204580, ultimately indicating that the S1P/S1PR3/p38 MAPK pathway contributes to the NF-κB p65 inflammatory response. Conclusion Our results demonstrate a critical role of Sphk1 in the post-traumatic SCI inflammatory cascade and present the Sphk1/S1P/S1PR3 axis as a potential target for therapeutic intervention to control neuroinflammation, relieve neuronal damage, and improve functional outcomes in SCI.
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Affiliation(s)
- Chenjian Wang
- Department of Orthopaedics, The Third Affiliated Hospital of Wenzhou Medical University, Rui'an People's Hospital, Wenzhou, 325200, Zhejiang, China
| | - Tianzhen Xu
- Department of Orthopaedics, Zhu'ji People's Hospital, Shaoxing, 311800, Zhejiang, China
| | - Brittany Bolduc Lachance
- Program in Trauma, Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Xiqiang Zhong
- Department of Orthopaedics, The Third Affiliated Hospital of Wenzhou Medical University, Rui'an People's Hospital, Wenzhou, 325200, Zhejiang, China
| | - Guangjie Shen
- Department of Orthopaedics, The Third Affiliated Hospital of Wenzhou Medical University, Rui'an People's Hospital, Wenzhou, 325200, Zhejiang, China
| | - Tao Xu
- Department of Orthopaedics, The Third Affiliated Hospital of Wenzhou Medical University, Rui'an People's Hospital, Wenzhou, 325200, Zhejiang, China
| | - Chengxuan Tang
- Department of Orthopaedics, The Third Affiliated Hospital of Wenzhou Medical University, Rui'an People's Hospital, Wenzhou, 325200, Zhejiang, China.
| | - Xiaofeng Jia
- Department of Neurosurgery, University of Maryland School of Medicine, 10 South Pine Street, MSTF Building 823, Baltimore, MD, 21201, USA. .,Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, 21201, USA. .,Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA. .,Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA. .,Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
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11
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Morani F, Doccini S, Chiorino G, Fattori F, Galatolo D, Sciarrillo E, Gemignani F, Züchner S, Bertini ES, Santorelli FM. Functional Network Profiles in ARSACS Disclosed by Aptamer-Based Proteomic Technology. Front Neurol 2021; 11:603774. [PMID: 33584503 PMCID: PMC7873355 DOI: 10.3389/fneur.2020.603774] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 12/16/2020] [Indexed: 11/13/2022] Open
Abstract
Although the genetic basis of autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) has been uncovered, our poor understanding of disease mechanisms requires new light on functional pathways and modifying factors to improve early diagnostic strategies and offer alternative treatment options in a rare condition with no cure. Investigation of the pathologic state combining disease models and quantitative omic approach might improve biomarkers discovery with possible implications in patients' diagnoses. In this study, we analyzed proteomics data obtained using the SomaLogic technology, comparing cell lysates from ARSACS patients and from a SACS KO SH-SY5Y neuroblastoma cell model. Single-stranded deoxyoligonucleotides, selected in vitro from large random libraries, bound and quantified molecular targets related to the neuroinflammation signaling pathway and to neuronal development. Changes in protein levels were further analyzed by bioinformatics and network approaches to identify biomarkers of ARSACS and functional pathways impaired in the disease. We identified novel significantly dysregulated biological processes related to neuroinflammation, synaptogenesis, and engulfment of cells in patients and in KO cells compared with controls. Among the differential expressed proteins found in this work, we identified several proteins encoded by genes already known to be mutated in other forms of neurodegeneration. This finding suggests that common dysfunctional networks could be therapeutic targets for future investigations.
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Affiliation(s)
- Federica Morani
- Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Stella Maris Foundation, Pisa, Italy.,Department of Biology, University of Pisa, Pisa, Italy
| | - Stefano Doccini
- Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Stella Maris Foundation, Pisa, Italy
| | - Giovanna Chiorino
- Laboratorio di Genomica, Fondazione Edo ed Elvo Tempia, Biella, Italy
| | - Fabiana Fattori
- Unit of Muscular and Neurodegenerative Disorders, Department of Neurosciences, Bambino Gesù Children's Hospital, Rome, Italy
| | - Daniele Galatolo
- Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Stella Maris Foundation, Pisa, Italy
| | - Elisa Sciarrillo
- Laboratorio di Genomica, Fondazione Edo ed Elvo Tempia, Biella, Italy
| | | | - Stephan Züchner
- Department of Human Genetics, Hussman Institute for Human Genomics, University of Miami, Miami, FL, United States
| | - Enrico Silvio Bertini
- Unit of Muscular and Neurodegenerative Disorders, Department of Neurosciences, Bambino Gesù Children's Hospital, Rome, Italy
| | - Filippo Maria Santorelli
- Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Stella Maris Foundation, Pisa, Italy
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12
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Wang X, Sun Y, Peng X, Naqvi SMAS, Yang Y, Zhang J, Chen M, Chen Y, Chen H, Yan H, Wei G, Hong P, Lu Y. The Tumorigenic Effect of Sphingosine Kinase 1 and Its Potential Therapeutic Target. Cancer Control 2020; 27:1073274820976664. [PMID: 33317322 PMCID: PMC8480355 DOI: 10.1177/1073274820976664] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Sphingosine kinase 1 (SPHK1) regulates cell proliferation and survival by converting sphingosine to the signaling mediator sphingosine 1-phosphate (S1P). SPHK1 is widely overexpressed in most cancers, promoting tumor progression and is associated with clinical prognosis. Numerous studies have explored SPHK1 as a promising target for cancer therapy. However, due to insufficient knowledge of SPHK1 oncogenic mechanisms, its inhibitors’ therapeutic potential in preventing and treating cancer still needs further investigation. In this review, we summarized the metabolic balance regulated by the SPHK1/S1P signaling pathway and highlighted the oncogenic mechanisms of SPHK1 via the upregulation of autophagy, proliferation, and survival, migration, angiogenesis and inflammation, and inhibition of apoptosis. Drug candidates targeting SPHK1 were also discussed at the end. This review provides new insights into the oncogenic effect of SPHK1 and sheds light on the future direction for targeting SPHK1 as cancer therapy.
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Affiliation(s)
- Xianwang Wang
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Health Science Center, Yangtze University, Jingzhou, Hubei, China
- Laboratory of Oncology, Center for Molecular Medicine, School of Basic Medicine, Health Science Center, Yangtze University, Jingzhou, Hubei, China
| | - Yong Sun
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Health Science Center, Yangtze University, Jingzhou, Hubei, China
| | - Xiaochun Peng
- Laboratory of Oncology, Center for Molecular Medicine, School of Basic Medicine, Health Science Center, Yangtze University, Jingzhou, Hubei, China
| | - Syed Manzar Abbas Shah Naqvi
- Laboratory of Oncology, Center for Molecular Medicine, School of Basic Medicine, Health Science Center, Yangtze University, Jingzhou, Hubei, China
| | - Yue Yang
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Health Science Center, Yangtze University, Jingzhou, Hubei, China
| | - Jing Zhang
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Health Science Center, Yangtze University, Jingzhou, Hubei, China
| | - Meiwen Chen
- Laboratory of Oncology, Center for Molecular Medicine, School of Basic Medicine, Health Science Center, Yangtze University, Jingzhou, Hubei, China
| | - Yuan Chen
- Laboratory of Oncology, Center for Molecular Medicine, School of Basic Medicine, Health Science Center, Yangtze University, Jingzhou, Hubei, China
| | - Hongyue Chen
- Laboratory of Oncology, Center for Molecular Medicine, School of Basic Medicine, Health Science Center, Yangtze University, Jingzhou, Hubei, China
| | - Huizi Yan
- Laboratory of Oncology, Center for Molecular Medicine, School of Basic Medicine, Health Science Center, Yangtze University, Jingzhou, Hubei, China
| | - Guangliang Wei
- Laboratory of Oncology, Center for Molecular Medicine, School of Basic Medicine, Health Science Center, Yangtze University, Jingzhou, Hubei, China
| | - Peng Hong
- The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen, Guangdong, China
| | - Yingying Lu
- The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen, Guangdong, China
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13
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Vucicevic L, Misirkic M, Ciric D, Martinovic T, Jovanovic M, Isakovic A, Markovic I, Saponjic J, Foretz M, Rabanal-Ruiz Y, Korolchuk VI, Trajkovic V. Transcriptional block of AMPK-induced autophagy promotes glutamate excitotoxicity in nutrient-deprived SH-SY5Y neuroblastoma cells. Cell Mol Life Sci 2020; 77:3383-3399. [PMID: 31720741 PMCID: PMC11105051 DOI: 10.1007/s00018-019-03356-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 10/16/2019] [Accepted: 10/28/2019] [Indexed: 02/07/2023]
Abstract
We investigated the role of autophagy, a controlled lysosomal degradation of cellular macromolecules and organelles, in glutamate excitotoxicity during nutrient deprivation in vitro. The incubation in low-glucose serum/amino acid-free cell culture medium synergized with glutamate in increasing AMP/ATP ratio and causing excitotoxic necrosis in SH-SY5Y human neuroblastoma cells. Glutamate suppressed starvation-triggered autophagy, as confirmed by diminished intracellular acidification, lower LC3 punctuation and LC3-I conversion to autophagosome-associated LC3-II, reduced expression of proautophagic beclin-1 and ATG5, increase of the selective autophagic target NBR1, and decreased number of autophagic vesicles. Similar results were observed in PC12 rat pheochromocytoma cells. Both glutamate-mediated excitotoxicity and autophagy inhibition in starved SH-SY5Y cells were reverted by NMDA antagonist memantine and mimicked by NMDA agonists D-aspartate and ibotenate. Glutamate reduced starvation-triggered phosphorylation of the energy sensor AMP-activated protein kinase (AMPK) without affecting the activity of mammalian target of rapamycin complex 1, a major negative regulator of autophagy. This was associated with reduced mRNA levels of autophagy transcriptional activators (FOXO3, ATF4) and molecules involved in autophagy initiation (ULK1, ATG13, FIP200), autophagosome nucleation/elongation (ATG14, beclin-1, ATG5), and autophagic cargo delivery to autophagosomes (SQSTM1). Glutamate-mediated transcriptional repression of autophagy was alleviated by overexpression of constitutively active AMPK. Genetic or pharmacological AMPK activation by AMPK overexpression or metformin, as well as genetic or pharmacological autophagy induction by TFEB overexpression or lithium chloride, reduced the sensitivity of nutrient-deprived SH-SY5Y cells to glutamate excitotoxicity. These data indicate that transcriptional inhibition of AMPK-dependent cytoprotective autophagy is involved in glutamate-mediated excitotoxicity during nutrient deprivation in vitro.
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Affiliation(s)
- Ljubica Vucicevic
- Department of Neurophysiology, Institute for Biological Research "Sinisa Stankovic", University of Belgrade, Belgrade, Serbia
| | - Maja Misirkic
- Department of Neurophysiology, Institute for Biological Research "Sinisa Stankovic", University of Belgrade, Belgrade, Serbia
| | - Darko Ciric
- Faculty of Medicine, Institute of Histology and Embryology, University of Belgrade, Belgrade, Serbia
| | - Tamara Martinovic
- Faculty of Medicine, Institute of Histology and Embryology, University of Belgrade, Belgrade, Serbia
| | - Maja Jovanovic
- Faculty of Medicine, Institute of Medical and Clinical Biochemistry, University of Belgrade, Belgrade, Serbia
| | - Aleksandra Isakovic
- Faculty of Medicine, Institute of Medical and Clinical Biochemistry, University of Belgrade, Belgrade, Serbia
| | - Ivanka Markovic
- Faculty of Medicine, Institute of Medical and Clinical Biochemistry, University of Belgrade, Belgrade, Serbia
| | - Jasna Saponjic
- Department of Neurobiology, Institute for Biological Research "Sinisa Stankovic", University of Belgrade, Belgrade, Serbia
| | - Marc Foretz
- Inserm U1016, Institut Cochin, Paris, France
- CNRS UMR8104, Paris, France
- Université Paris Descartes, Sorbonne Paris cité, Paris, France
| | - Yoana Rabanal-Ruiz
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK
- Regional Center for Biomedical Research, University of Castilla-La Mancha, Ciudad Real, Spain
| | - Viktor I Korolchuk
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK
| | - Vladimir Trajkovic
- Faculty of Medicine, Institute of Microbiology and Immunology, University of Belgrade, Dr. Subotica 1, 11000, Belgrade, Serbia.
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14
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Zhang Y, He Q, Yang M, Hua S, Ma Q, Guo L, Wu X, Zhang C, Fu X, Liu J. Dichloromethane extraction from Piper nigrum L. and P. longum L. to mitigate ischemic stroke by activating the AKT/mTOR signaling pathway to suppress autophagy. Brain Res 2020; 1749:147047. [PMID: 32781091 DOI: 10.1016/j.brainres.2020.147047] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 08/03/2020] [Accepted: 08/04/2020] [Indexed: 01/14/2023]
Abstract
Dichloromethane fraction (DF) of Piper nigrum L. and P. longum L. (PnL and PlL), has been found to exert a protective effect against ischemic stroke in rats. However, the regulatory mechanism exerted by PnL and PIL have not been fully elucidated. In this study, we found that DF greatly ameliorated cerebral ischemic injury in a rat model of permanent middle cerebral artery occlusion (pMCAO). The neurological score, behavioral assessment, brain infarct volume, phosphorylation of AKT (p-AKT), phosphorylation mTOR (p-mTOR), and Atg7 protein levels were determined. Additionally, we discovered that DF pretreatment reduced infarct volume, neurological score, and brain damage. Furthermore, DF therapy caused the downregulation of Atg7 and p-AKT expression, as well as the upregulation of p-mTOR expression. In conclusion, our findings indicated that DF treatment can reduce brain damage and inhibit apoptosis and autophagy by activating the Akt-mTOR signaling pathway in ischemic stroke.
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Affiliation(s)
- Yiwei Zhang
- School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, China
| | - Qianxiong He
- School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, China
| | - Miao Yang
- School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, China
| | - Shiyao Hua
- School of Pharmacy, Ningxia Medical University, Yinchuan, China
| | - Quanrui Ma
- School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, China
| | - Li Guo
- School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, China
| | - Xiaomin Wu
- School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, China
| | - Chun Zhang
- Ningxia Key Laboratory of Cerebrocranial Diseases, Ningxia Medical University, Yinchuan, Ningxia 750004, China
| | - Xueyan Fu
- School of Pharmacy, Ningxia Medical University, Yinchuan, China; Key Laboratory of Hui Ethnic Medicine Modernization Ministry of Education, Ningxia Medical University, Yinchuan, China.
| | - Juan Liu
- School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, China.
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15
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Lejault P, Moruno-Manchon JF, Vemu SM, Honarpisheh P, Zhu L, Kim N, Urayama A, Monchaud D, McCullough LD, Tsvetkov AS. Regulation of autophagy by DNA G-quadruplexes. Autophagy 2020; 16:2252-2259. [PMID: 32420812 DOI: 10.1080/15548627.2020.1769991] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Guanine-rich DNA strands can form secondary structures known as G-quadruplexes (G4-DNA or G4s). G4-DNA is important for the regulation of replication and transcription. We recently showed that the expression of Atg7, a gene that is critical for macroautophagy/autophagy, is controlled by G4-DNA in neurons. We demonstrated that the transcription factor SUB1/PC4 and the G4-DNA-specific antibody HF2 bind to a putative G4-DNA motif located in the Atg7 gene. Stabilizing G4-DNA with the G4-ligand pyridostatin (PDS) downregulates Atg7 expression in neurons. Here, we further investigated how G4-DNA in the Atg7 gene is stabilized by PDS. We show that PDS can form 1:1 and 2:1 complexes with the Atg7's G4. We also demonstrate that PDS downregulates the ATG7 protein and the expression of Atg7 in astrocytes as well as in neurons. Together with our previous findings, these data establish a novel G4-DNA-associated mechanism of autophagy regulation at a transcriptional level in neurons and astrocytes.
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Affiliation(s)
- Pauline Lejault
- UBFC Dijon, Institut De Chimie Moléculaire (ICMUB) , Dijon, France
| | - Jose F Moruno-Manchon
- Department of Neurology, The University of Texas McGovern Medical School at Houston , Houston, TX, USA
| | - Sree M Vemu
- Summer Research Program, the University of Texas Medical School at Houston , TX, USA
| | - Pedram Honarpisheh
- Department of Neurology, The University of Texas McGovern Medical School at Houston , Houston, TX, USA.,The University of Texas Graduate School of Biomedical Sciences , Houston, TX, USA
| | - Liang Zhu
- Biostatistics and Epidemiology Research Design Core Center for Clinical and Translational Sciences, The University of Texas McGovern Medical School at Houston , Houston, TX, USA.,Department of Internal Medicine, The University of Texas McGovern Medical School at Houston , Houston, TX, USA
| | - Nayun Kim
- The University of Texas Graduate School of Biomedical Sciences , Houston, TX, USA.,Department of Microbiology and Molecular Genetics, The University of Texas McGovern Medical School at Houston , TX
| | - Akihiko Urayama
- Department of Neurology, The University of Texas McGovern Medical School at Houston , Houston, TX, USA.,The University of Texas Graduate School of Biomedical Sciences , Houston, TX, USA
| | - David Monchaud
- UBFC Dijon, Institut De Chimie Moléculaire (ICMUB) , Dijon, France
| | - Louise D McCullough
- Department of Neurology, The University of Texas McGovern Medical School at Houston , Houston, TX, USA.,The University of Texas Graduate School of Biomedical Sciences , Houston, TX, USA
| | - Andrey S Tsvetkov
- Department of Neurology, The University of Texas McGovern Medical School at Houston , Houston, TX, USA.,The University of Texas Graduate School of Biomedical Sciences , Houston, TX, USA.,UTHealth Consortium on Aging, The University of Texas McGovern Medical School , Houston, TX, USA
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16
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Uzor NE, McCullough LD, Tsvetkov AS. Peroxisomal Dysfunction in Neurological Diseases and Brain Aging. Front Cell Neurosci 2020; 14:44. [PMID: 32210766 PMCID: PMC7075811 DOI: 10.3389/fncel.2020.00044] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 02/18/2020] [Indexed: 12/17/2022] Open
Abstract
Peroxisomes exist in most cells, where they participate in lipid metabolism, as well as scavenging the reactive oxygen species (ROS) that are produced as by-products of their metabolic functions. In certain tissues such as the liver and kidneys, peroxisomes have more specific roles, such as bile acid synthesis in the liver and steroidogenesis in the adrenal glands. In the brain, peroxisomes are critically involved in creating and maintaining the lipid content of cell membranes and the myelin sheath, highlighting their importance in the central nervous system (CNS). This review summarizes the peroxisomal lifecycle, then examines the literature that establishes a link between peroxisomal dysfunction, cellular aging, and age-related disorders that affect the CNS. This review also discusses the gap of knowledge in research on peroxisomes in the CNS.
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Affiliation(s)
- Ndidi-Ese Uzor
- Department of Neurobiology and Anatomy, University of Texas McGovern Medical School, Houston, TX, United States
- The University of Texas Graduate School of Biomedical Sciences, Houston, TX, United States
| | - Louise D. McCullough
- The University of Texas Graduate School of Biomedical Sciences, Houston, TX, United States
- Department of Neurology, University of Texas McGovern Medical School, Houston, TX, United States
- UTHealth Consortium on Aging, University of Texas McGovern Medical School, Houston, TX, United States
| | - Andrey S. Tsvetkov
- Department of Neurobiology and Anatomy, University of Texas McGovern Medical School, Houston, TX, United States
- The University of Texas Graduate School of Biomedical Sciences, Houston, TX, United States
- UTHealth Consortium on Aging, University of Texas McGovern Medical School, Houston, TX, United States
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17
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Finkbeiner S. The Autophagy Lysosomal Pathway and Neurodegeneration. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a033993. [PMID: 30936119 DOI: 10.1101/cshperspect.a033993] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The autophagy lysosomal pathway (ALP) is a major mechanism for degrading intracellular macromolecules. The catabolic products can then be used by the cell for energy or as building blocks to make other macromolecules. Since its discovery, a variety of cellular pathways have emerged that target components with varying specificity for lysosomal degradation. Under some circumstances, lysosomes may release their contents into the extracellular space where they may serve signaling or pathogenic functions. The ALP is active in healthy cells, and the level of activity can be regulated by nutrient-sensing and metabolic signaling pathways. The ALP is the primary pathway by which lipids and damaged organelles are degraded and may be the only pathway capable of degrading aggregated proteins. As such, there has been intense interest in understanding the role of the ALP in the accumulation of aggregated misfolded proteins characteristic of many of the major adult-onset neurodegenerative diseases. This review focuses on recent advances in our understanding of the ALP and its potential relationship to the pathogenesis and treatment of neurodegenerative diseases.
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Affiliation(s)
- Steven Finkbeiner
- Gladstone Institutes, San Francisco, California 94158.,Departments of Neurology and Physiology, University of California, San Francisco, California 94158
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18
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Benito-Cuesta I, Ordóñez-Gutiérrez L, Wandosell F. AMPK activation does not enhance autophagy in neurons in contrast to MTORC1 inhibition: different impact on β-amyloid clearance. Autophagy 2020; 17:656-671. [PMID: 32075509 DOI: 10.1080/15548627.2020.1728095] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The physiological AKT-MTORC1 and AMPK signaling pathways are considered key nodes in the regulation of anabolism-catabolism, and particularly of macroautophagy/autophagy. Indeed, it is reported that these are altered processes in neurodegenerative proteinopathies such as Alzheimer disease (AD), mainly characterized by deposits of β-amyloid (Aβ) and hyperphosphorylated MAPT. These accumulations disrupt the optimal neuronal proteostasis, and hence, the recovery/enhancement of autophagy has been proposed as a therapeutic approach against these proteinopathies. The purpose of the present study was to characterize the modulation of autophagy by MTORC1 and AMPK signaling pathways in the highly specialized neurons, as well as their repercussions on Aβ production. Using a double transgenic mice model of AD, we demonstrated that MTORC1 inhibition, either in vivo or ex vivo (primary neuronal cultures), was able to reduce amyloid secretion through moderate autophagy induction in neurons. The pharmacological prevention of autophagy in neurons augmented the Aβ secretion and reversed the effect of rapamycin, confirming the anti-amyloidogenic effects of autophagy in neurons. Inhibition of AMPK with compound C generated the expected decrease in autophagy induction, though surprisingly did not increase the Aβ secretion. In contrast, increased activity of AMPK with metformin, AICAR, 2DG, or by gene overexpression did not enhance autophagy but had different effects on Aβ secretion: whereas metformin and 2DG diminished the secreted Aβ levels, AICAR and PRKAA1/AMPK gene overexpression increased them. We conclude that AMPK has a significantly different role in primary neurons than in other reported cells, lacking a direct effect on autophagy-dependent amyloidosis.Abbreviations: 2DG: 2-deoxy-D-glucose; Aβ: β-amyloid; ACACA: acetyl-CoA carboxylase alpha; ACTB: actin beta; AD: Alzheimer disease; AICAR: 5-aminoimidazole-4-carboxamide-1-β-riboside; AKT: AKT kinases group (AKT1 [AKT serine/threonine kinase 1], AKT2 and AKT3); AMPK: adenosine 5'-monophosphate (AMP)-activated protein kinase; APP: amyloid beta precursor protein; APP/PSEN1: B6.Cg-Tg (APPSwe, PSEN1dE9) 85Dbo/J; ATG: autophagy related; ATP: adenosine triphosphate; BafA1: bafilomycin A1; CA: constitutively active; CGN: cerebellar granule neuron; CoC/compound C: dorsommorphin dihydrochloride; ELISA: enzyme-linked immunosorbent assay; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GFP: green fluorescent protein; Gmax: GlutaMAX™; IN1: PIK3C3/VPS34-IN1; KI: kinase-inactive; MAP1LC3B/LC3: microtubule associated protein 1 light chain 3; MAPT/TAU: microtubule associated protein tau; Metf: metformin; MRT: MRT68921; MTORC1: mechanistic target of rapamycin kinase complex 1; NBR1: NBR1 autophagy cargo receptor; PRKAA: 5'-AMP-activated protein kinase catalytic subunit alpha; PtdIns3K: phosphatidylinositol 3-kinase; Rapa: rapamycin; RPS6KB1/S6K: ribosomal protein S6 (RPS6) kinase polypeptide 1; SCR: scramble; SQSTM1/p62: sequestosome 1; ULK1/2: unc-51 like autophagy activating kinase 1/2; WT: wild type.
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Affiliation(s)
- Irene Benito-Cuesta
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Universidad Autónoma de Madrid, Madrid, Spain
| | - Lara Ordóñez-Gutiérrez
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Universidad Autónoma de Madrid, Madrid, Spain
| | - Francisco Wandosell
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Universidad Autónoma de Madrid, Madrid, Spain.,Alzheimer's Disease and Other Degenerative Dementias, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
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19
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Grassi S, Mauri L, Prioni S, Cabitta L, Sonnino S, Prinetti A, Giussani P. Sphingosine 1-Phosphate Receptors and Metabolic Enzymes as Druggable Targets for Brain Diseases. Front Pharmacol 2019; 10:807. [PMID: 31427962 PMCID: PMC6689979 DOI: 10.3389/fphar.2019.00807] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 06/21/2019] [Indexed: 12/12/2022] Open
Abstract
The central nervous system is characterized by a high content of sphingolipids and by a high diversity in terms of different structures. Stage- and cell-specific sphingolipid metabolism and expression are crucial for brain development and maintenance toward adult age. On the other hand, deep dysregulation of sphingolipid metabolism, leading to altered sphingolipid pattern, is associated with the majority of neurological and neurodegenerative diseases, even those totally lacking a common etiological background. Thus, sphingolipid metabolism has always been regarded as a promising pharmacological target for the treatment of brain disorders. However, any therapeutic hypothesis applied to complex amphipathic sphingolipids, components of cellular membranes, has so far failed probably because of the high regional complexity and specificity of the different biological roles of these structures. Simpler sphingosine-based lipids, including ceramide and sphingosine 1-phosphate, are important regulators of brain homeostasis, and, thanks to the relative simplicity of their metabolic network, they seem a feasible druggable target for the treatment of brain diseases. The enzymes involved in the control of the levels of bioactive sphingoids, as well as the receptors engaged by these molecules, have increasingly allured pharmacologists and clinicians, and eventually fingolimod, a functional antagonist of sphingosine 1-phosphate receptors with immunomodulatory properties, was approved for the therapy of relapsing-remitting multiple sclerosis. Considering the importance of neuroinflammation in many other brain diseases, we would expect an extension of the use of such analogs for the treatment of other ailments in the future. Nevertheless, many aspects other than neuroinflammation are regulated by bioactive sphingoids in healthy brain and dysregulated in brain disease. In this review, we are addressing the multifaceted possibility to address the metabolism and biology of bioactive sphingosine 1-phosphate as novel targets for the development of therapeutic paradigms and the discovery of new drugs.
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Affiliation(s)
- Sara Grassi
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Laura Mauri
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Simona Prioni
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Livia Cabitta
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Sandro Sonnino
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Alessandro Prinetti
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Paola Giussani
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
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20
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Yin S, Miao Z, Tan Y, Wang P, Xu X, Zhang C, Hou W, Huang J, Xu H. SPHK1-induced autophagy in peritoneal mesothelial cell enhances gastric cancer peritoneal dissemination. Cancer Med 2019; 8:1731-1743. [PMID: 30791228 PMCID: PMC6488120 DOI: 10.1002/cam4.2041] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Revised: 01/10/2019] [Accepted: 01/31/2019] [Indexed: 12/24/2022] Open
Abstract
Gastric cancer peritoneal dissemination (GCPD) has been recognized as the most common form of metastasis in advanced gastric cancer (GC), and the survival is pessimistic. The injury of mesothelial cells plays an important role in GCPD. However, its molecular mechanism is not entirely clear. Here, we focused on the sphingosine kinase 1 (SPHK1) in human peritoneal mesothelial cells (HPMCs) which regulates HPMCs autophagy in GCPD progression. Initially, we analyzed SPHK1 expression immunohistochemically in 120 GC peritoneal tissues, and found high SPHK1 expression to be significantly associated with LC3B expression and peritoneal recurrence, leading to poor prognosis. Using a coculture system, we observed that GC cells promoted HPMCs autophagy and this process was inhibited by blocking TGF-β1 secreted from GC cells. Autophagic HPMCs induced adhesion and invasion of GC cells. We also confirmed that knockdown of SPHK1 expression in HPMCs inhibited TGF-β1-induced autophagy. In addition, SPHK1-driven autophagy of HPMCs accelerated GC cells occurrence of GCPD in vitro and in vivo. Moreover, we explored the relationship between autophagy and fibrosis in HPMCs, observing that overexpression of SPHK1 induced HPMCs fibrosis, while the inhibition of autophagy weakened HPMCs fibrosis. Taken together, our results provided new insights for understanding the mechanisms of GCPD and established SPHK1 as a novel target for GCPD.
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Affiliation(s)
- Songcheng Yin
- Department of Surgical Oncology, First Affiliated Hospital of China Medical University, Shenyang, China.,Key Laboratory of Gastric Cancer Molecular Pathology of Liaoning Province, Heping District, Shenyang, China
| | - Zhifeng Miao
- Department of Surgical Oncology, First Affiliated Hospital of China Medical University, Shenyang, China.,Key Laboratory of Gastric Cancer Molecular Pathology of Liaoning Province, Heping District, Shenyang, China
| | - Yuen Tan
- Department of Surgical Oncology, First Affiliated Hospital of China Medical University, Shenyang, China.,Key Laboratory of Gastric Cancer Molecular Pathology of Liaoning Province, Heping District, Shenyang, China
| | - Pengliang Wang
- Department of Surgical Oncology, First Affiliated Hospital of China Medical University, Shenyang, China.,Key Laboratory of Gastric Cancer Molecular Pathology of Liaoning Province, Heping District, Shenyang, China
| | - Xiaoyu Xu
- Department of Gynecology, The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen, China
| | - Chao Zhang
- Department of Surgical Oncology, First Affiliated Hospital of China Medical University, Shenyang, China.,Key Laboratory of Gastric Cancer Molecular Pathology of Liaoning Province, Heping District, Shenyang, China
| | - Wenbin Hou
- Department of Surgical Oncology, First Affiliated Hospital of China Medical University, Shenyang, China.,Key Laboratory of Gastric Cancer Molecular Pathology of Liaoning Province, Heping District, Shenyang, China
| | - Jinyu Huang
- Department of Surgical Oncology, First Affiliated Hospital of China Medical University, Shenyang, China.,Key Laboratory of Gastric Cancer Molecular Pathology of Liaoning Province, Heping District, Shenyang, China
| | - Huimian Xu
- Department of Surgical Oncology, First Affiliated Hospital of China Medical University, Shenyang, China.,Key Laboratory of Gastric Cancer Molecular Pathology of Liaoning Province, Heping District, Shenyang, China
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21
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Wang G, Bieberich E. Sphingolipids in neurodegeneration (with focus on ceramide and S1P). Adv Biol Regul 2018; 70:51-64. [PMID: 30287225 PMCID: PMC6251739 DOI: 10.1016/j.jbior.2018.09.013] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 09/20/2018] [Accepted: 09/21/2018] [Indexed: 04/14/2023]
Abstract
For many decades, research on sphingolipids associated with neurodegenerative disease focused on alterations in glycosphingolipids, particularly glycosylceramides (cerebrosides), sulfatides, and gangliosides. This seemed quite natural since many of these glycolipids are constituents of myelin and accumulated in lipid storage diseases (sphingolipidoses) resulting from enzyme deficiencies in glycolipid metabolism. With the advent of recognizing ceramide and its derivative, sphingosine-1-phosphate (S1P), as key players in lipid cell signaling and regulation of cell death and survival, research focus shifted toward these two sphingolipids. Ceramide and S1P are invoked in a plethora of cell biological processes participating in neurodegeneration such as ER stress, autophagy, dysregulation of protein and lipid transport, exosome secretion and neurotoxic protein spreading, neuroinflammation, and mitochondrial dysfunction. Hence, it is timely to discuss various functions of ceramide and S1P in neurodegenerative disease and to define sphingolipid metabolism and cell signaling pathways as potential targets for therapy.
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Affiliation(s)
- Guanghu Wang
- Department of Physiology, University of Kentucky, Lexington, KY, USA
| | - Erhard Bieberich
- Department of Physiology, University of Kentucky, Lexington, KY, USA.
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22
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Moruno-Manchon JF, Koellhoffer EC, Gopakumar J, Hambarde S, Kim N, McCullough LD, Tsvetkov AS. The G-quadruplex DNA stabilizing drug pyridostatin promotes DNA damage and downregulates transcription of Brca1 in neurons. Aging (Albany NY) 2018; 9:1957-1970. [PMID: 28904242 PMCID: PMC5636668 DOI: 10.18632/aging.101282] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 08/25/2017] [Indexed: 01/01/2023]
Abstract
The G-quadruplex is a non-canonical DNA secondary structure formed by four DNA strands containing multiple runs of guanines. G-quadruplexes play important roles in DNA recombination, replication, telomere maintenance, and regulation of transcription. Small molecules that stabilize the G-quadruplexes alter gene expression in cancer cells. Here, we hypothesized that the G-quadruplexes regulate transcription in neurons. We discovered that pyridostatin, a small molecule that specifically stabilizes G-quadruplex DNA complexes, induced neurotoxicity and promoted the formation of DNA double–strand breaks (DSBs) in cultured neurons. We also found that pyridostatin downregulated transcription of the Brca1 gene, a gene that is critical for DSB repair. Importantly, in an in vitro gel shift assay, we discovered that an antibody specific to the G-quadruplex structure binds to a synthetic oligonucleotide, which corresponds to the first putative G-quadruplex in the Brca1 gene promoter. Our results suggest that the G-quadruplex complexes regulate transcription in neurons. Studying the G-quadruplexes could represent a new avenue for neurodegeneration and brain aging research.
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Affiliation(s)
- Jose F Moruno-Manchon
- Department of Neurobiology and Anatomy, the University of Texas McGovern Medical School at Houston, TX 77030, USA
| | - Edward C Koellhoffer
- Department of Neurology, the University of Texas McGovern Medical School at Houston, TX 77030, USA
| | - Jayakrishnan Gopakumar
- Summer Research Program at the University of Texas McGovern Medical School at Houston, TX 77030, USA
| | - Shashank Hambarde
- Department of Microbiology and Molecular Genetics, the University of Texas McGovern Medical School at Houston, TX 77030, USA
| | - Nayun Kim
- Department of Microbiology and Molecular Genetics, the University of Texas McGovern Medical School at Houston, TX 77030, USA.,The University of Texas Graduate School of Biomedical Sciences, Houston, TX 77030, USA
| | - Louise D McCullough
- Department of Neurology, the University of Texas McGovern Medical School at Houston, TX 77030, USA.,The University of Texas Graduate School of Biomedical Sciences, Houston, TX 77030, USA
| | - Andrey S Tsvetkov
- Department of Neurobiology and Anatomy, the University of Texas McGovern Medical School at Houston, TX 77030, USA.,The University of Texas Graduate School of Biomedical Sciences, Houston, TX 77030, USA.,UTHealth Consortium on Aging, the University of Texas McGovern Medical School, Houston, TX 77030, USA
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23
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Abstract
Macroautophagy (herein referred to as autophagy) is a highly conserved stress response that engulfs damaged proteins, lipids, and/or organelles within double-membrane vesicles called autophagosomes for lysosomal degradation. Dysregulated autophagy is a hallmark of cancer; and thus, there is great interest in modulating autophagy for cancer therapy. Sphingolipids regulate each step of autophagosome biogenesis with roles for sphingolipid metabolites and enzymes spanning from the initial step of de novo ceramide synthesis to the sphingosine-1-phosphate lyase 1-mediated exit from the sphingolipid pathway. Notably, sphingolipid metabolism occurs at several of the organelles that contribute to autophagosome biogenesis to suggest that local changes in sphingolipids may regulate autophagy. As sphingolipid metabolism is frequently dysregulated in cancer, a molecular understanding of sphingolipids in stress-induced autophagy may provide insight into the mechanisms driving tumor development and progression. On the contrary, modulation of sphingolipid metabolites and/or enzymes can induce autophagy-dependent cell death for cancer therapy. This chapter will overview the major steps in mammalian autophagy, discuss the regulation of each step by sphingolipid metabolites, and describe the functions of sphingolipid-mediated autophagy in cancer. While our understanding of the signaling and biophysical properties of sphingolipids in autophagy remains in its infancy, the unique cross talk between the two pathways is an exciting area for further development, particularly in the context of cancer therapy.
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Affiliation(s)
- Megan M Young
- Department of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - Hong-Gang Wang
- Department of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, United States
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24
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Moruno-Manchon JF, Uzor NE, Ambati CR, Shetty V, Putluri N, Jagannath C, McCullough LD, Tsvetkov AS. Sphingosine kinase 1-associated autophagy differs between neurons and astrocytes. Cell Death Dis 2018; 9:521. [PMID: 29743513 PMCID: PMC5943283 DOI: 10.1038/s41419-018-0599-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 04/05/2018] [Accepted: 04/12/2018] [Indexed: 02/07/2023]
Abstract
Autophagy is a degradative pathway for removing aggregated proteins, damaged organelles, and parasites. Evidence indicates that autophagic pathways differ between cell types. In neurons, autophagy plays a homeostatic role, compared to a survival mechanism employed by starving non-neuronal cells. We investigated if sphingosine kinase 1 (SK1)-associated autophagy differs between two symbiotic brain cell types—neurons and astrocytes. SK1 synthesizes sphingosine-1-phosphate, which regulates autophagy in non-neuronal cells and in neurons. We found that benzoxazine autophagy inducers upregulate SK1 and neuroprotective autophagy in neurons, but not in astrocytes. Starvation enhances SK1-associated autophagy in astrocytes, but not in neurons. In astrocytes, SK1 is cytoprotective and promotes the degradation of an autophagy substrate, mutant huntingtin, the protein that causes Huntington’s disease. Overexpressed SK1 is unexpectedly toxic to neurons, and its toxicity localizes to the neuronal soma, demonstrating an intricate relationship between the localization of SK1’s activity and neurotoxicity. Our results underscore the importance of cell type-specific autophagic differences in any efforts to target autophagy therapeutically.
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Affiliation(s)
- Jose F Moruno-Manchon
- Department of Neurobiology and Anatomy, The University of Texas McGovern Medical School, Houston, TX, 77030, USA
| | - Ndidi-Ese Uzor
- Department of Neurobiology and Anatomy, The University of Texas McGovern Medical School, Houston, TX, 77030, USA.,The University of Texas Graduate School of Biomedical Sciences, Houston, TX, 77030, USA
| | - Chandrashekar R Ambati
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Vivekananda Shetty
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Nagireddy Putluri
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Chinnaswamy Jagannath
- Department of Pathology and Laboratory Medicine, The University of Texas McGovern Medical School, Houston, TX, 77030, USA
| | - Louise D McCullough
- The University of Texas Graduate School of Biomedical Sciences, Houston, TX, 77030, USA.,Department of Neurology, The University of Texas McGovern Medical School at Houston, Houston, TX, 77030, USA
| | - Andrey S Tsvetkov
- Department of Neurobiology and Anatomy, The University of Texas McGovern Medical School, Houston, TX, 77030, USA. .,The University of Texas Graduate School of Biomedical Sciences, Houston, TX, 77030, USA. .,UT Health Consortium on Aging, The University of Texas McGovern Medical School, Houston, TX, 77030, USA.
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25
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Xu C, Zhang W, Liu S, Wu W, Qin M, Huang J. Activation of the SphK1/ERK/p-ERK pathway promotes autophagy in colon cancer cells. Oncol Lett 2018; 15:9719-9724. [PMID: 29928348 PMCID: PMC6004663 DOI: 10.3892/ol.2018.8588] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 03/16/2018] [Indexed: 12/22/2022] Open
Abstract
Sphingosine kinase 1 (SphK1) is a master kinase that catalyzes the synthesis of sphingosine 1 phosphate and participates in the regulation of cell proliferation and autophagy. The present study aimed to assess the effects of the activation of the SphK1/extracellular signal-regulated kinase (ERK)/phosphorylated (p-)ERK pathway in the regulation of autophagy in colon cancer (HT-29) cells. Inverted fluorescence microscopy was used to detect the expression of green fluorescent protein (GFP) in the SphK1-overexpressing HT-29 cells [SphK1(+)-HT-29] and the negative control HT-29 cells (NC-HT-29). Western blotting was used to detect the protein expression levels of SphK1, ERK1/2, p-ERK1/2, as well as those of the autophagy-associated markers LC3A, ATG5, and ULK1. Protein localization and expression of the LC3A antibody were detected by immunofluorescence. The results demonstrated that GFP was similarly expressed in SphK1(+)-HT-29 and NC-HT-29 cells. However, significantly increased SphK1 mRNA and protein expression levels were detected in SphK1(+)-HT-29 cells compared with in NC-HT-29 cells, which resulted in upregulated ERK/p-ERK. Furthermore, the protein expression levels of the three autophagy-associated markers increased. LC3A protein was localized in the cytoplasm of SphK1(+)-HT-29 cells, indicating autophagy. In summary, the findings of the present study suggested that activation of the SphK1/ERK/p-ERK pathway promotes autophagy in colon cancer HT-29 cells.
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Affiliation(s)
- Chunyan Xu
- Department of Gastroenterology, The Second Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi 530007, P.R. China
| | - Wenlu Zhang
- Department of Respiratory Medicine, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
| | - Shiquan Liu
- Department of Gastroenterology, The Second Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi 530007, P.R. China
| | - Wenhong Wu
- Department of Gastroenterology, The Second Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi 530007, P.R. China
| | - Mengbin Qin
- Department of Gastroenterology, The Second Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi 530007, P.R. China
| | - Jiean Huang
- Department of Gastroenterology, The Second Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi 530007, P.R. China
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26
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Di Pardo A, Maglione V. The S1P Axis: New Exciting Route for Treating Huntington's Disease. Trends Pharmacol Sci 2018; 39:468-480. [PMID: 29559169 DOI: 10.1016/j.tips.2018.02.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Revised: 02/22/2018] [Accepted: 02/27/2018] [Indexed: 11/17/2022]
Abstract
Huntington's disease (HD) is a single-gene inheritable neurodegenerative disorder with an associated complex molecular pathogenic profile that renders it the most 'curable incurable' brain disorder. Continuous effort in the field has contributed to the recent discovery of novel potential pathogenic mechanisms. Findings in preclinical models of the disease as well as in human post-mortem brains from affected patients demonstrate that alteration of the sphingosine-1-phosphate (S1P) axis may represent a possible key player in the pathogenesis of the disease and may act as a potential actionable drug target for the development of more targeted and effective therapeutic approaches. The relevance of the path of this new 'therapeutic route' is underscored by the fact that some drugs targeting the S1P axis are currently in clinical trials for the treatment of other brain disorders.
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Affiliation(s)
- Alba Di Pardo
- Centre for Neurogenetics and Rare Diseases, IRCCS Neuromed, 86077 Pozzilli (IS), Italy
| | - Vittorio Maglione
- Centre for Neurogenetics and Rare Diseases, IRCCS Neuromed, 86077 Pozzilli (IS), Italy.
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27
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Lima S, Takabe K, Newton J, Saurabh K, Young MM, Leopoldino AM, Hait NC, Roberts JL, Wang HG, Dent P, Milstien S, Booth L, Spiegel S. TP53 is required for BECN1- and ATG5-dependent cell death induced by sphingosine kinase 1 inhibition. Autophagy 2018; 14:942-957. [PMID: 29368980 DOI: 10.1080/15548627.2018.1429875] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The bioactive sphingolipid metabolite sphingosine-1-phosphate (S1P) and the enzyme that produces it, SPHK1 (sphingosine kinase 1), regulate many processes important for the etiology of cancer. It has been suggested that SPHK1 levels are regulated by the tumor suppressor protein TP53, a key regulator of cell cycle arrest, apoptosis, and macroautophagy/autophagy. However, little is still known of the relationship between TP53 and SPHK1 activity in the regulation of these processes. To explore this link, we examined the effects of inhibiting SPHK1 in wild-type and TP53 null cancer cell lines. SK1-I, an analog of sphingosine and isozyme-specific SPHK1 inhibitor, suppressed cancer cell growth and clonogenic survival in a TP53-dependent manner. It also more strongly enhanced intrinsic apoptosis in wild-type TP53 cells than in isogenic TP53 null cells. Intriguingly, SK1-I induced phosphorylation of TP53 on Ser15, which increases its transcriptional activity. Consequently, levels of TP53 downstream targets such as pro-apoptotic members of the BCL2 family, including BAX, BAK1, and BID were increased in wild-type but not in TP53 null cells. Inhibition of SPHK1 also increased the formation of autophagic and multivesicular bodies, and increased processing of LC3 and its localization within acidic compartments in a TP53-dependent manner. SK1-I also induced massive accumulation of vacuoles, enhanced autophagy, and increased cell death in an SPHK1-dependent manner that also required TP53 expression. Importantly, downregulation of the key regulators of autophagic flux, BECN1 and ATG5, dramatically decreased the cytotoxicity of SK1-I only in cells with TP53 expression. Hence, our results reveal that TP53 plays an important role in vacuole-associated cell death induced by SPHK1 inhibition in cancer cells.
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Affiliation(s)
- Santiago Lima
- a Department of Biochemistry and Molecular Biology , Virginia Commonwealth University School of Medicine , Richmond , VA USA
| | - Kazuaki Takabe
- a Department of Biochemistry and Molecular Biology , Virginia Commonwealth University School of Medicine , Richmond , VA USA.,c Department of Surgery and the Massey Cancer Center , Virginia Commonwealth University School of Medicine , Richmond , VA USA
| | - Jason Newton
- a Department of Biochemistry and Molecular Biology , Virginia Commonwealth University School of Medicine , Richmond , VA USA
| | - Kumar Saurabh
- a Department of Biochemistry and Molecular Biology , Virginia Commonwealth University School of Medicine , Richmond , VA USA
| | - Megan M Young
- d Department of Pharmacology , Department of Pediatrics , Penn State University College of Medicine , Hershey , PA , USA
| | - Andreia Machado Leopoldino
- b Department of Clinical Analysis, Toxicology and Food Sciences , School of Pharmaceutical Sciences of Riberião Preto , University of São Paulo , Ribeirão Preto , SP , Brazil
| | - Nitai C Hait
- a Department of Biochemistry and Molecular Biology , Virginia Commonwealth University School of Medicine , Richmond , VA USA
| | - Jane L Roberts
- a Department of Biochemistry and Molecular Biology , Virginia Commonwealth University School of Medicine , Richmond , VA USA
| | - Hong-Gang Wang
- d Department of Pharmacology , Department of Pediatrics , Penn State University College of Medicine , Hershey , PA , USA
| | - Paul Dent
- a Department of Biochemistry and Molecular Biology , Virginia Commonwealth University School of Medicine , Richmond , VA USA
| | - Sheldon Milstien
- a Department of Biochemistry and Molecular Biology , Virginia Commonwealth University School of Medicine , Richmond , VA USA
| | - Laurence Booth
- a Department of Biochemistry and Molecular Biology , Virginia Commonwealth University School of Medicine , Richmond , VA USA
| | - Sarah Spiegel
- a Department of Biochemistry and Molecular Biology , Virginia Commonwealth University School of Medicine , Richmond , VA USA
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28
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Justice MJ, Bronova I, Schweitzer KS, Poirier C, Blum JS, Berdyshev EV, Petrache I. Inhibition of acid sphingomyelinase disrupts LYNUS signaling and triggers autophagy. J Lipid Res 2018; 59:596-606. [PMID: 29378782 DOI: 10.1194/jlr.m080242] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 12/05/2017] [Indexed: 12/22/2022] Open
Abstract
Activation of the lysosomal ceramide-producing enzyme, acid sphingomyelinase (ASM), by various stresses is centrally involved in cell death and has been implicated in autophagy. We set out to investigate the role of the baseline ASM activity in maintaining physiological functions of lysosomes, focusing on the lysosomal nutrient-sensing complex (LYNUS), a lysosomal membrane-anchored multiprotein complex that includes mammalian target of rapamycin (mTOR) and transcription factor EB (TFEB). ASM inhibition with imipramine or sphingomyelin phosphodiesterase 1 (SMPD1) siRNA in human lung cells, or by transgenic Smpd1+/- haploinsufficiency of mouse lungs, markedly reduced mTOR- and P70-S6 kinase (Thr 389)-phosphorylation and modified TFEB in a pattern consistent with its activation. Inhibition of baseline ASM activity significantly increased autophagy with preserved degradative potential. Pulse labeling of sphingolipid metabolites revealed that ASM inhibition markedly decreased sphingosine (Sph) and Sph-1-phosphate (S1P) levels at the level of ceramide hydrolysis. These findings suggest that ASM functions to maintain physiological mTOR signaling and inhibit autophagy and implicate Sph and/or S1P in the control of lysosomal function.
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Affiliation(s)
- Matthew J Justice
- Departments of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202; Department of Medicine, National Jewish Health, Denver, CO 80206
| | - Irina Bronova
- Department of Medicine, National Jewish Health, Denver, CO 80206
| | - Kelly S Schweitzer
- Department of Medicine, National Jewish Health, Denver, CO 80206; Departments of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Christophe Poirier
- Departments of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Janice S Blum
- Departments of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202
| | | | - Irina Petrache
- Departments of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202; Department of Medicine, National Jewish Health, Denver, CO 80206; Departments of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202.
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29
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Moruno-Manchon JF, Uzor NE, Kesler SR, Wefel JS, Townley DM, Nagaraja AS, Pradeep S, Mangala LS, Sood AK, Tsvetkov AS. TFEB ameliorates the impairment of the autophagy-lysosome pathway in neurons induced by doxorubicin. Aging (Albany NY) 2017; 8:3507-3519. [PMID: 27992857 PMCID: PMC5270683 DOI: 10.18632/aging.101144] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 12/12/2016] [Indexed: 11/25/2022]
Abstract
Doxorubicin, a commonly used chemotherapy agent, induces severe cardio- and neurotoxicity. Molecular mechanisms of cardiotoxicity have been extensively studied, but mechanisms by which doxorubicin exhibits its neurotoxic properties remain unclear. Here, we show that doxorubicin impairs neuronal autophagy, leading to the accumulation of an autophagy substrate p62. Neurons treated with doxorubicin contained autophagosomes, damaged mitochondria, and lipid droplets. The brains from mice treated with pegylated liposomal doxorubicin exhibited autophagosomes, often with mitochondria, lipofuscin, and lipid droplets. Interestingly, lysosomes were less acidic in doxorubicin-treated neurons. Overexpression of the transcription factor EB (TFEB), which controls the autophagy-lysosome axis, increased survival of doxorubicin-treated neurons. 2-Hydroxypropyl-β-cyclodextrin (HPβCD), an activator of TFEB, also promoted neuronal survival, decreased the levels of p62, and lowered the pH in lysosomes. Taken together, substantial changes induced by doxorubicin contribute to neurotoxicity, cognitive disturbances in cancer patients and survivors, and accelerated brain aging. The TFEB pathway might be a new approach for mitigating damage of neuronal autophagy caused by doxorubicin.
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Affiliation(s)
- Jose Felix Moruno-Manchon
- Department of Neurobiology and Anatomy, The University of Texas McGovern Medical School at Houston, Houston, TX 77030, USA
| | - Ndidi-Ese Uzor
- Department of Neurobiology and Anatomy, The University of Texas McGovern Medical School at Houston, Houston, TX 77030, USA.,The University of Texas Graduate School of Biomedical Sciences, Houston, TX 77030, USA
| | - Shelli R Kesler
- Department of Neuro-Oncology, the University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Jeffrey S Wefel
- Department of Neuro-Oncology, the University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Debra M Townley
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Archana Sidalaghatta Nagaraja
- Department of Gynecologic Oncology and Reproductive Medicine, the University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA.,Center for RNA Interference and Non-Coding RNA, the University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA.,Department of Cancer Biology, the University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Sunila Pradeep
- Department of Gynecologic Oncology and Reproductive Medicine, the University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA.,Center for RNA Interference and Non-Coding RNA, the University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA.,Department of Cancer Biology, the University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Lingegowda S Mangala
- Department of Gynecologic Oncology and Reproductive Medicine, the University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA.,Center for RNA Interference and Non-Coding RNA, the University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA.,Department of Cancer Biology, the University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Anil K Sood
- Department of Gynecologic Oncology and Reproductive Medicine, the University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA.,Center for RNA Interference and Non-Coding RNA, the University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA.,Department of Cancer Biology, the University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Andrey S Tsvetkov
- Department of Neurobiology and Anatomy, The University of Texas McGovern Medical School at Houston, Houston, TX 77030, USA.,The University of Texas Graduate School of Biomedical Sciences, Houston, TX 77030, USA
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30
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Sphingosine Kinase 1 Cooperates with Autophagy to Maintain Endocytic Membrane Trafficking. Cell Rep 2017; 17:1532-1545. [PMID: 27806293 DOI: 10.1016/j.celrep.2016.10.019] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 09/15/2016] [Accepted: 10/05/2016] [Indexed: 11/21/2022] Open
Abstract
Sphingosine kinase 1 (Sphk1) associates with early endocytic membranes during endocytosis; however, the role of sphingosine or sphingosine-1-phosphate as the critical metabolite in endocytic trafficking has not been established. Here, we demonstrate that the recruitment of Sphk1 to sphingosine-enriched endocytic vesicles and the generation of sphingosine-1-phosphate facilitate membrane trafficking along the endosomal pathway. Exogenous sphingosine and sphingosine-based Sphk1 inhibitors induce the Sphk1-dependent fusion of endosomal membranes to accumulate enlarged late endosomes and amphisomes enriched in sphingolipids. Interestingly, Sphk1 also appears to facilitate endosomal fusion independent of its catalytic activity, given that catalytically inactive Sphk1G82D is recruited to endocytic membranes by sphingosine or sphingosine-based Sphk1 inhibitor and promotes membrane fusion. Furthermore, we reveal that the clearance of enlarged endosomes is dependent on the activity of ceramide synthase, lysosomal biogenesis, and the restoration of autophagic flux. Collectively, these studies uncover intersecting roles for Sphk1, sphingosine, and autophagic machinery in endocytic membrane trafficking.
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Sphingosine kinase 2 activates autophagy and protects neurons against ischemic injury through interaction with Bcl-2 via its putative BH3 domain. Cell Death Dis 2017; 8:e2912. [PMID: 28682313 PMCID: PMC5550846 DOI: 10.1038/cddis.2017.289] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 05/26/2017] [Accepted: 05/29/2017] [Indexed: 01/05/2023]
Abstract
Our previous findings suggest that sphingosine kinase 2 (SPK2) mediates ischemic tolerance and autophagy in cerebral preconditioning. The aim of this study was to determine by which mechanism SPK2 activates autophagy in neural cells. In both primary murine cortical neurons and HT22 hippocampal neuronal cells, overexpression of SPK2 increased LC3II and enhanced the autophagy flux. SPK2 overexpression protected cortical neurons against oxygen glucose deprivation (OGD) injury, as evidenced by improvement of neuronal morphology, increased cell viability and reduced lactate dehydrogenase release. The inhibition of autophagy effectively suppressed the neuroprotective effect of SPK2. SPK2 overexpression reduced the co-immunoprecipitation of Beclin-1 and Bcl-2, while Beclin-1 knockdown inhibited SPK2-induced autophagy. Both co-immunoprecipitation and GST pull-down analysis suggest that SPK2 directly interacts with Bcl-2. SPK2 might interact to Bcl-2 in the cytoplasm. Notably, an SPK2 mutant with L219A substitution in its putative BH3 domain was not able to activate autophagy. A Tat peptide fused to an 18-amino acid peptide encompassing the native, but not the L219A mutated BH3 domain of SPK2 activated autophagy in neural cells. The Tat-SPK2 peptide also protected neurons against OGD injury through autophagy activation. These results suggest that SPK2 interacts with Bcl-2 via its BH3 domain, thereby dissociating it from Beclin-1 and activating autophagy. The observation that Tat-SPK2 peptide designed from the BH3 domain of SPK2 activates autophagy and protects neural cells against OGD injury suggest that this structure may provide the basis for a novel class of therapeutic agents against ischemic stroke.
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Moruno-Manchon JF, Uzor NE, Blasco-Conesa MP, Mannuru S, Putluri N, Furr-Stimming EE, Tsvetkov AS. Inhibiting sphingosine kinase 2 mitigates mutant Huntingtin-induced neurodegeneration in neuron models of Huntington disease. Hum Mol Genet 2017; 26:1305-1317. [PMID: 28175299 PMCID: PMC6251541 DOI: 10.1093/hmg/ddx046] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 01/20/2017] [Accepted: 02/02/2017] [Indexed: 12/22/2022] Open
Abstract
Huntington disease (HD) is the most common inherited neurodegenerative disorder. It has no cure. The protein huntingtin causes HD, and mutations to it confer toxic functions to the protein that lead to neurodegeneration. Thus, identifying modifiers of mutant huntingtin-mediated neurotoxicity might be a therapeutic strategy for HD. Sphingosine kinases 1 (SK1) and 2 (SK2) synthesize sphingosine-1-phosphate (S1P), a bioactive lipid messenger critically involved in many vital cellular processes, such as cell survival. In the nucleus, SK2 binds to and inhibits histone deacetylases 1 and 2 (HDAC1/2). Inhibiting both HDACs has been suggested as a potential therapy in HD. Here, we found that SK2 is nuclear in primary neurons and, unexpectedly, overexpressed SK2 is neurotoxic in a dose-dependent manner. SK2 promotes DNA double-strand breaks in cultured primary neurons. We also found that SK2 is hyperphosphorylated in the brain samples from a model of HD, the BACHD mice. These data suggest that the SK2 pathway may be a part of a pathogenic pathway in HD. ABC294640, an inhibitor of SK2, reduces DNA damage in neurons and increases survival in two neuron models of HD. Our results identify a novel regulator of mutant huntingtin-mediated neurotoxicity and provide a new target for developing therapies for HD.
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Affiliation(s)
- Jose F. Moruno-Manchon
- Department of Neurobiology and Anatomy, The University of Texas McGovern Medical School, Houston, TX 77030, USA
| | - Ndidi-Ese Uzor
- Department of Neurobiology and Anatomy, The University of Texas McGovern Medical School, Houston, TX 77030, USA
- The University of Texas Graduate School of Biomedical Sciences, Houston, TX 77030, USA
| | - Maria P. Blasco-Conesa
- Department of Neurobiology and Anatomy, The University of Texas McGovern Medical School, Houston, TX 77030, USA
| | - Sishira Mannuru
- The University of Texas Medical Training Program, Houston, TX 77030, USA
| | - Nagireddy Putluri
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Erin E. Furr-Stimming
- Department of Neurology, The University of Texas McGovern Medical School, Houston, TX 77030, USA
| | - Andrey S. Tsvetkov
- Department of Neurobiology and Anatomy, The University of Texas McGovern Medical School, Houston, TX 77030, USA
- The University of Texas Graduate School of Biomedical Sciences, Houston, TX 77030, USA
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