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Abstract
BACKGROUND Variants in the patatin-like phospholipase domain containing 6 (PNPLA6) gene cause a broad spectrum of neurological disorders characterized by gait disturbance, visual impairment, anterior hypopituitarism, and hair anomalies. This review examines the clinical, cellular, and biochemical features found across the five PNPLA6-related diseases, with a focus on future questions to be addressed. MATERIALS AND METHODS A literature review was performed on published clinical reports on patients with PNPLA6 variants. Additionally, in vitro and in vivo models used to study the encoded protein, Neuropathy Target Esterase (NTE), are summarized to lend mechanistic perspective to human diseases. RESULTS Biallelic pathogenic PNPLA6 variants cause five systemic neurological disorders: spastic paraplegia type 39, Gordon-Holmes, Boucher-Neuhäuser, Laurence-Moon, and Oliver-McFarlane syndromes. PNPLA6 encodes NTE, an enzyme involved in maintaining phospholipid homeostasis and trafficking in the nervous system. Retinal disease presents with a unique chorioretinal dystrophy that is phenotypically similar to choroideremia and Leber congenital amaurosis. Animal and cellular models support a loss-of-function mechanism. CONCLUSIONS Clinicians should be aware of choroideremia-like ocular presentation in patients who also experience growth defects, motor dysfunction, and/or hair anomalies. Although NTE biochemistry is well characterized, further research on the relationship between genotype and the presence or absence of retinopathy should be explored to improve diagnosis and prognosis.
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Affiliation(s)
- James Liu
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Robert B Hufnagel
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
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The phospholipase A 2 superfamily as a central hub of bioactive lipids and beyond. Pharmacol Ther 2023; 244:108382. [PMID: 36918102 DOI: 10.1016/j.pharmthera.2023.108382] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 03/06/2023] [Accepted: 03/07/2023] [Indexed: 03/13/2023]
Abstract
In essence, "phospholipase A2" (PLA2) means a group of enzymes that release fatty acids and lysophospholipids by hydrolyzing the sn-2 position of glycerophospholipids. To date, more than 50 enzymes possessing PLA2 or related lipid-metabolizing activities have been identified in mammals, and these are subdivided into several families in terms of their structures, catalytic mechanisms, tissue/cellular localizations, and evolutionary relationships. From a general viewpoint, the PLA2 superfamily has mainly been implicated in signal transduction, driving the production of a wide variety of bioactive lipid mediators. However, a growing body of evidence indicates that PLA2s also contribute to phospholipid remodeling or recycling for membrane homeostasis, fatty acid β-oxidation for energy production, and barrier lipid formation on the body surface. Accordingly, PLA2 enzymes are considered one of the key regulators of a broad range of lipid metabolism, and perturbation of specific PLA2-driven lipid pathways often disrupts tissue and cellular homeostasis and may be associated with a variety of diseases. This review covers current understanding of the physiological functions of the PLA2 superfamily, focusing particularly on the two major intracellular PLA2 families (Ca2+-dependent cytosolic PLA2s and Ca2+-independent patatin-like PLA2s) as well as other PLA2 families, based on studies using gene-manipulated mice and human diseases in combination with comprehensive lipidomics.
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Huang FF, Chang PA, Sun LX, Qin WZ, Han LP, Chen R. The destruction box is involved in the degradation of the NTE family proteins by the proteasome. Mol Biol Rep 2016; 43:1285-1292. [PMID: 27558092 DOI: 10.1007/s11033-016-4063-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 08/16/2016] [Indexed: 01/16/2023]
Abstract
Neuropathy target esterase (NTE) and NTE-related esterase (NRE) are endoplasmic reticulum (ER) membrane-anchored proteins belonging to the NTE protein family. NTE and NRE are degraded by macroautophagy and by the ubiquitin-proteasome pathway. However, the regulation of NTE and NRE by proteasome has not been well understood. Western blotting showed that the deletion of the regulatory region of NTE and NRE led to protein accumulation compared with that of the corresponding wild-type proteins. Further, deletion and site-directed mutagenesis experiments demonstrated that the destruction (D) box was required for the proteasomal degradation of NTE and NRE. However, unlike the deletion of the regulatory region, the deletion of the D box did not affect the subcellular localisation of NTE or NRE or disrupt the ER. Moreover, the deletion of the D box or the regulatory region of NTE has similar inhibitory effects on cell growth, which are greater than those produced by the full-length NTE. Here, for the first time, we show that the D box is involved in the regulation of NTE family proteins by the proteasome but not in their subcellular localisation. In addition, these results suggest that the NTE overexpression-mediated inhibition of cell growth is related to active protein levels but not to its ER disruption effect.
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Affiliation(s)
- Fei-Fei Huang
- Key Laboratory of Molecular Biology, College of Bio-information, Chongqing University of Posts and Telecommunications, Chongqing, 400065, People's Republic of China
| | - Ping-An Chang
- Key Laboratory of Molecular Biology, College of Bio-information, Chongqing University of Posts and Telecommunications, Chongqing, 400065, People's Republic of China.
| | - Lan-Xi Sun
- Key Laboratory of Molecular Biology, College of Bio-information, Chongqing University of Posts and Telecommunications, Chongqing, 400065, People's Republic of China
| | - Wen-Zhen Qin
- Key Laboratory of Molecular Biology, College of Bio-information, Chongqing University of Posts and Telecommunications, Chongqing, 400065, People's Republic of China
| | - Li-Ping Han
- Key Laboratory of Molecular Biology, College of Bio-information, Chongqing University of Posts and Telecommunications, Chongqing, 400065, People's Republic of China
| | - Rui Chen
- CAS Key Lab for Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology of China, Beijing, 100190, People's Republic of China
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Hu Y, Chen J, Fan H, Xie P, He J. A review of neurotoxicity of microcystins. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016; 23:7211-7219. [PMID: 26857003 DOI: 10.1007/s11356-016-6073-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 01/06/2016] [Indexed: 06/05/2023]
Abstract
Cyanobacterial blooms-produced microcystins are secondary metabolites which can accumulate in the food chain and contaminate water, thus posing a potential threat to the health of aquatic animals and even humans. Microcystin toxicity affects not only the liver but also the other organs, i.e., the brain. The serious neurotoxicity effects caused by microcystins then lead to various symptoms. This review focuses on the neurotoxicity of microcystins. Microcystins can cross blood-brain barrier with the transport of Oatps/OATPs, causing neurostructural, functional, and behavioral changes. In this review, potential uptake mechanisms and neurotoxicity mechanisms are summarized, including neurotransmissions, neurochannels, signal transduction, oxidative stress, and cytoskeleton disruption. However, further researches are needed for detailed studies on signaling pathways and the downstream pathways of neurotoxicity of microcystins.
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Affiliation(s)
- Yufei Hu
- Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, No.7 Donghu South Road, Wuhan, 430072, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jun Chen
- Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, No.7 Donghu South Road, Wuhan, 430072, China
| | - Huihui Fan
- Department of Preventive Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Ping Xie
- Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, No.7 Donghu South Road, Wuhan, 430072, China.
| | - Jun He
- Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, No.7 Donghu South Road, Wuhan, 430072, China
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Mishra M, Saurabh S, Maurya R, Mudawal A, Parmar D, Singh PK. Proteome analysis of Bemisia tabaci suggests specific targets for RNAi mediated control. J Proteomics 2016; 132:93-102. [DOI: 10.1016/j.jprot.2015.11.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 10/29/2015] [Accepted: 11/21/2015] [Indexed: 11/28/2022]
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Long DX, Wang P, Sun YJ, Chen R, Wu YJ. Neuropathy Target Esterase Is Degraded by the Ubiquitin-Proteasome Pathway with ARA54 as the Ubiquitin Ligase. Biochemistry 2015; 54:7385-92. [PMID: 26606397 DOI: 10.1021/acs.biochem.5b00879] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Neuropathy target esterase (NTE) is an endoplasmic reticulum membrane-associated phospholipase B, which is essential for embryonic and nervous system development. However, the regulation of NTE at the protein level had not been thoroughly investigated. Our previous study showed that NTE was degraded not only by the macroautophagy-lysosome pathway but also by the ubiquitin-proteasome pathway. Here we further reveal that androgen receptor-associated protein 54 (ARA54) regulated the ubiquitin-proteasome degradation of NTE. We find that deletion of the regulatory domain of NTE, which possesses a putative destruction box and thus is essential for its degradation by the proteasome, prevented its degradation by the proteasome. In addition, we demonstrate that ARA54, which has a RING finger domain and E3 ligase activity, interacts directly with NTE. Overexpression of ARA54 downregulates the protein level of NTE, and knockdown of ARA54 inhibits the degradation of NTE. The mutation in the RING domain of ARA54 blocks the degradation of NTE by ARA54, which indicates that the RING domain is essential for ARA54's E3 activity. These findings suggest that ARA54 acts as the ubiquitin ligase to regulate the ubiquitin-proteasome degradation of NTE.
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Affiliation(s)
- Ding-Xin Long
- Laboratory of Molecular Toxicology, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences , Beijing 100101, P. R. China.,School of Public Health, University of South China , Hengyang 421001, P. R. China
| | - Pan Wang
- Laboratory of Molecular Toxicology, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences , Beijing 100101, P. R. China
| | - Ying-Jian Sun
- Laboratory of Molecular Toxicology, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences , Beijing 100101, P. R. China.,Department of Veterinary Medicine and Animal Science, Beijing Agriculture College , Beijing 102206, P. R. China
| | - Rui Chen
- Laboratory of Molecular Toxicology, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences , Beijing 100101, P. R. China
| | - Yi-Jun Wu
- Laboratory of Molecular Toxicology, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences , Beijing 100101, P. R. China
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7
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Chen JX, Wu YJ. CREB is required for cAMP/PKA signals upregulating neuropathy target esterase expression. DNA Cell Biol 2013; 32:199-205. [PMID: 23517531 DOI: 10.1089/dna.2012.1835] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Neuropathy target esterase (NTE), which has been proposed as the primary target of organophosphorus compounds that cause delayed neuropathy with degeneration of nerve axons, is expressed primarily in neural cells but is also detected in non-neural cells. However, little is known about the regulation of NTE gene in cells. We found that a cyclic-AMP (cAMP)-response element (CRE) exists in the 5' flanking sequence of NTE gene in HeLa cells, which implies that NTE may be regulated by the transcription factor cAMP-response element-binding protein (CREB). In the study, knockdown of CREB decreased the protein and mRNA levels of NTE and inhibited the upregulation by cAMP/PKA signaling. Moreover, we observed that knockdown of CREB significantly decreased luciferase activity of the NTE gene promoter, while it had no effect on that of the CREB binding sites of mutated NTE gene promoter and truncated NTE gene promoter lacking the CREB binding site. cAMP/PKA signals could increase NTE reporter gene activity, while knockdown of CREB inhibited the increase. We found that the transcription factor CREB can bind to the promoter sequence of NTE by chromatin immunoprecipitation. In conclusion, we provided evidence that CREB is required for cAMP/PKA signals upregulating NTE expression in HeLa cells.
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Affiliation(s)
- Jia-Xiang Chen
- Laboratory of Molecular Toxicology, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, People's Republic of China
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Huang QY, Huang HQ. Differential expression profile of membrane proteins in zebrafish (Danio rerio
) brain exposed to methyl parathion. Proteomics 2011; 11:3743-56. [DOI: 10.1002/pmic.201100084] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 06/29/2011] [Accepted: 07/01/2011] [Indexed: 12/12/2022]
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Murakami M, Taketomi Y, Miki Y, Sato H, Hirabayashi T, Yamamoto K. Recent progress in phospholipase A₂ research: from cells to animals to humans. Prog Lipid Res 2010; 50:152-92. [PMID: 21185866 DOI: 10.1016/j.plipres.2010.12.001] [Citation(s) in RCA: 368] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mammalian genomes encode genes for more than 30 phospholipase A₂s (PLA₂s) or related enzymes, which are subdivided into several classes including low-molecular-weight secreted PLA₂s (sPLA₂s), Ca²+-dependent cytosolic PLA₂s (cPLA₂s), Ca²+-independent PLA₂s (iPLA₂s), platelet-activating factor acetylhydrolases (PAF-AHs), lysosomal PLA₂s, and a recently identified adipose-specific PLA. Of these, the intracellular cPLA₂ and iPLA₂ families and the extracellular sPLA₂ family are recognized as the "big three". From a general viewpoint, cPLA₂α (the prototypic cPLA₂ plays a major role in the initiation of arachidonic acid metabolism, the iPLA₂ family contributes to membrane homeostasis and energy metabolism, and the sPLA₂ family affects various biological events by modulating the extracellular phospholipid milieus. The cPLA₂ family evolved along with eicosanoid receptors when vertebrates first appeared, whereas the diverse branching of the iPLA₂ and sPLA₂ families during earlier eukaryote development suggests that they play fundamental roles in life-related processes. During the past decade, data concerning the unexplored roles of various PLA₂ enzymes in pathophysiology have emerged on the basis of studies using knockout and transgenic mice, the use of specific inhibitors, and information obtained from analysis of human diseases caused by mutations in PLA₂ genes. This review focuses on current understanding of the emerging biological functions of PLA₂s and related enzymes.
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Affiliation(s)
- Makoto Murakami
- Lipid Metabolism Project, The Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan.
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Wang M, Wang D, Lin L, Hong H. Protein profiles in zebrafish (Danio rerio) brains exposed to chronic microcystin-LR. CHEMOSPHERE 2010; 81:716-724. [PMID: 20800265 DOI: 10.1016/j.chemosphere.2010.07.061] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 07/20/2010] [Accepted: 07/28/2010] [Indexed: 05/29/2023]
Abstract
Microcystin-LR (MCLR) is a commonly encountered blue-green algal hepatotoxin and a known inhibitor of cellular protein phosphatase (PP), however, little is known about its neurotoxicity. This study investigated the protein profiles of zebrafish (Danio rerio) brains chronically exposed to MCLR concentrations (2 or 20 μg L(-1)) using the proteomic approach. The results showed that MCLR strikingly enhanced toxin accumulation and the PP activity in zebrafish brains after 30 d exposure. Comparison of two-dimensional electrophoresis protein profiles of MCLR exposed and non-exposed zebrafish brains revealed that the abundance of 30 protein spots was remarkably altered in response to MCLR exposure. These proteins are involved in cytoskeleton assembly, macromolecule metabolism, oxidative stress, signal transduction, and other functions (e.g. transporting, protein degradation, apoptosis and translation), indicating that MCLR toxicity in the fish brain is complex and diverse. The chronic neurotoxicity of MCLR might initiate the PP pathway via an upregulation of PP2C in the zebrafish brain, in addition to the reactive oxygen species pathway. Additionally, the increase of vitellogenin abundance in MCLR exposed zebrafish brains suggested that MCLR might mimic the effects of endocrine disrupting chemicals. This study demonstrated that MCLR causes neurotoxicity in zebrafish at the proteomic level, which provides a new insight into MCLR toxicity in aquatic organisms and human beings.
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Affiliation(s)
- Minghua Wang
- State Key Laboratory of Marine Environmental Science/Environmental Science Research Center, Xiamen University, Xiamen 361005, People's Republic of China
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Organophosphate-sensitive lipases modulate brain lysophospholipids, ether lipids and endocannabinoids. Chem Biol Interact 2008; 175:355-64. [PMID: 18495101 DOI: 10.1016/j.cbi.2008.04.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2007] [Revised: 04/08/2008] [Accepted: 04/10/2008] [Indexed: 12/28/2022]
Abstract
Lipases play key roles in nearly all cells and organisms. Potent and selective inhibitors help to elucidate their physiological functions and associated metabolic pathways. Organophosphorus (OP) compounds are best known for their anticholinesterase properties but selectivity for lipases and other targets can also be achieved through structural optimization. This review considers several lipid systems in brain modulated by highly OP-sensitive lipases. Neuropathy target esterase (NTE) hydrolyzes lysophosphatidylcholine (lysoPC) as a preferred substrate. Gene deletion of NTE in mice is embryo lethal and the heterozygotes are hyperactive. NTE is very sensitive in vitro and in vivo to direct-acting OP delayed neurotoxicants and the related NTE-related esterase (NTE-R) is also inhibited in vivo. KIAA1363 hydrolyzes acetyl monoalkylglycerol ether (AcMAGE) of the platelet-activating factor (PAF) de novo biosynthetic pathway and is a marker of cancer cell invasiveness. It is also a detoxifying enzyme that hydrolyzes chlorpyrifos oxon (CPO) and some other potent insecticide metabolites. Monoacylglycerol lipase and fatty acid amide hydrolase regulate endocannabinoid levels with roles in motility, pain and memory. Inhibition of these enzymes in mice by OPs, such as isopropyl dodecylfluorophosphonate (IDFP), leads to dramatic elevation of brain endocannabinoids and distinct cannabinoid-dependent behavior. Hormone-sensitive lipase that hydrolyzes cholesteryl esters and diacylglycerols is a newly recognized in vivo CPO- and IDFP-target in brain. The OP chemotype can therefore be used in proteomic and metabolomic studies to further elucidate the biological function and toxicological significance of lipases in lipid metabolism. Only the first steps have been taken to achieve appropriate selective action for OP therapeutic agents.
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