1
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Wang Y, Wakelam MJO, Bankaitis VA, McDermott MI. The wide world of non-mammalian phospholipase D enzymes. Adv Biol Regul 2024; 91:101000. [PMID: 38081756 DOI: 10.1016/j.jbior.2023.101000] [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: 11/10/2023] [Accepted: 11/15/2023] [Indexed: 02/25/2024]
Abstract
Phospholipase D (PLD) hydrolyses phosphatidylcholine (PtdCho) to produce free choline and the critically important lipid signaling molecule phosphatidic acid (PtdOH). Since the initial discovery of PLD activities in plants and bacteria, PLDs have been identified in a diverse range of organisms spanning the taxa. While widespread interest in these proteins grew following the discovery of mammalian isoforms, research into the PLDs of non-mammalian organisms has revealed a fascinating array of functions ranging from roles in microbial pathogenesis, to the stress responses of plants and the developmental patterning of flies. Furthermore, studies in non-mammalian model systems have aided our understanding of the entire PLD superfamily, with translational relevance to human biology and health. Increasingly, the promise for utilization of non-mammalian PLDs in biotechnology is also being recognized, with widespread potential applications ranging from roles in lipid synthesis, to their exploitation for agricultural and pharmaceutical applications.
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Affiliation(s)
- Y Wang
- Department of Cell Biology & Genetics, Texas A&M Health Science Center, College Station, TX, 77843, USA; Department of Microbiology, University of Washington, Seattle, WA98109, USA
| | - M J O Wakelam
- Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, United Kingdom
| | - V A Bankaitis
- Department of Cell Biology & Genetics, Texas A&M Health Science Center, College Station, TX, 77843, USA; Department of Biochemistry & Biophysics, Texas A&M University, College Station, TX, 77843, USA; Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - M I McDermott
- Department of Cell Biology & Genetics, Texas A&M Health Science Center, College Station, TX, 77843, USA.
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2
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Issleny BM, Jamjoum R, Majumder S, Stiban J. Sphingolipids: From structural components to signaling hubs. Enzymes 2023; 54:171-201. [PMID: 37945171 DOI: 10.1016/bs.enz.2023.07.003] [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] [Indexed: 11/12/2023]
Abstract
In late November 2019, Prof. Lina M. Obeid passed away from cancer, a disease she spent her life researching and studying its intricate molecular underpinnings. Along with her husband, Prof. Yusuf A. Hannun, Obeid laid down the foundations of sphingolipid biochemistry and oversaw its remarkable evolution over the years. Lipids are a class of macromolecules that are primarily associated with cellular architecture. In fact, lipids constitute the perimeter of the cell in such a way that without them, there cannot be cells. Hence, much of the early research on lipids identified the function of this class of biological molecules as merely structural. Nevertheless, unlike proteins, carbohydrates, and nucleic acids, lipids are elaborately diverse as they are not made up of monomers in polymeric forms. This diversity in structure is clearly mirrored by functional pleiotropy. In this chapter, we focus on a major subset of lipids, sphingolipids, and explore their historic rise from merely inert structural components of plasma membranes to lively and necessary signaling molecules that transmit various signals and control many cellular processes. We will emphasize the works of Lina Obeid since she was an integral pillar of the sphingolipid research world.
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Affiliation(s)
- Batoul M Issleny
- Department of Pharmacy, Birzeit University, West Bank, Palestine
| | - Rama Jamjoum
- Department of Pharmacy, Birzeit University, West Bank, Palestine
| | | | - Johnny Stiban
- Department of Biology and Biochemistry, Birzeit University, West Bank, Palestine.
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3
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Velazquez FN, Hernandez-Corbacho M, Trayssac M, Stith JL, Bonica J, Jean B, Pulkoski-Gross MJ, Carroll BL, Salama MF, Hannun YA, Snider AJ. Bioactive sphingolipids: Advancements and contributions from the laboratory of Dr. Lina M. Obeid. Cell Signal 2020; 79:109875. [PMID: 33290840 PMCID: PMC8244749 DOI: 10.1016/j.cellsig.2020.109875] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 12/01/2020] [Accepted: 12/02/2020] [Indexed: 02/06/2023]
Abstract
Sphingolipids and their synthetic enzymes have emerged as critical mediators in numerous diseases including inflammation, aging, and cancer. One enzyme in particular, sphingosine kinase (SK) and its product sphingosine-1-phosphate (S1P), has been extensively implicated in these processes. SK catalyzes the phosphorylation of sphingosine to S1P and exists as two isoforms, SK1 and SK2. In this review, we will discuss the contributions from the laboratory of Dr. Lina M. Obeid that have defined the roles for several bioactive sphingolipids in signaling and disease with an emphasis on her work defining SK1 in cellular fates and pathobiologies including proliferation, senescence, apoptosis, and inflammation.
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Affiliation(s)
- Fabiola N Velazquez
- Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; Cancer Center, Stony Brook University, Stony Brook, NY 11794, USA
| | - Maria Hernandez-Corbacho
- Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; Cancer Center, Stony Brook University, Stony Brook, NY 11794, USA
| | - Magali Trayssac
- Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; Cancer Center, Stony Brook University, Stony Brook, NY 11794, USA
| | - Jeffrey L Stith
- Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; Cancer Center, Stony Brook University, Stony Brook, NY 11794, USA
| | - Joseph Bonica
- Cancer Center, Stony Brook University, Stony Brook, NY 11794, USA; Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11790, USA
| | - Bernandie Jean
- Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; Cancer Center, Stony Brook University, Stony Brook, NY 11794, USA
| | - Michael J Pulkoski-Gross
- Cancer Center, Stony Brook University, Stony Brook, NY 11794, USA; Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11790, USA
| | - Brittany L Carroll
- Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11790, USA
| | - Mohamed F Salama
- Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; Cancer Center, Stony Brook University, Stony Brook, NY 11794, USA; Department of Biochemistry, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Egypt
| | - Yusuf A Hannun
- Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; Cancer Center, Stony Brook University, Stony Brook, NY 11794, USA
| | - Ashley J Snider
- Department of Nutritional Sciences, College of Agriculture and Life Sciences, University of Arizona, Tucson, AZ 85721, USA.
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4
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Li L, Li J, Sun J, Yi P, Li C, Zhou Z, Xin M, Sheng J, Shuai L, Li Z, Ling D, He X, Zheng F, Liu G, Tang Y. Role of Phospholipase D Inhibitor in Regulating Expression of Senescencerelated Phospholipase D gene in Postharvest Longan Fruit. Curr Bioinform 2019. [DOI: 10.2174/1574893614666190503162645] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background:
Phospholipase D (PLD)is closely related to browning and senescence of
postharvest longan fruit.
Objective:
This study investigated the effects of 2-butanol (a PLD inhibitor) on the expression and
regulation of PLD during storage of longan fruit at a low temperature.
Methods:
Senescence-related quality indices showed that the 2-butanol-treated fruit presented lower
pericarp browning index, pulp breakdown index and total soluble solid value than the untreated
fruit.
Results:
The fruit treated by 60 µL/L 2-butanol exhibited the strongest inhibition on senescence,
which significantly delayed changes in weight, titratable acidity content, total soluble solid content
and ascorbic acid content. This treatment maintained a high level of total phenolic content and
caused significant inhibition on pericarp browning and pulp breakdown. Through ELISA method,
60 µL/L 2-butanol treatment also reduced PLD activity. Real-time RT-PCR (RT-qPCR) results
showed that PLD mRNA expression level was inhibited by 60 µL/L 2-butanol within 15 days.
Western-blotting results further confirmed the differential expression of PLD during storage, and a
relatively higher expression for PLD protein was found in control compared to the 2-butanoltreated
fruit during 15-d storage.
Conclusion:
These results provided a scientific basis and reference to further investigating postharvest
longan quality maintenance by regulating the PLD gene expression.
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Affiliation(s)
- Li Li
- Agro-food Science and Technology Research Institute, Guangxi Academy of Agricultural Sciences, 174 East Daxue Road, 530007 Nanning, China
| | - Jiemin Li
- Agro-food Science and Technology Research Institute, Guangxi Academy of Agricultural Sciences, 174 East Daxue Road, 530007 Nanning, China
| | - Jian Sun
- Agro-food Science and Technology Research Institute, Guangxi Academy of Agricultural Sciences, 174 East Daxue Road, 530007 Nanning, China
| | - Ping Yi
- Agro-food Science and Technology Research Institute, Guangxi Academy of Agricultural Sciences, 174 East Daxue Road, 530007 Nanning, China
| | - Changbao Li
- Agro-food Science and Technology Research Institute, Guangxi Academy of Agricultural Sciences, 174 East Daxue Road, 530007 Nanning, China
| | - Zhugui Zhou
- Agro-food Science and Technology Research Institute, Guangxi Academy of Agricultural Sciences, 174 East Daxue Road, 530007 Nanning, China
| | - Ming Xin
- Agro-food Science and Technology Research Institute, Guangxi Academy of Agricultural Sciences, 174 East Daxue Road, 530007 Nanning, China
| | - Jinfeng Sheng
- Agro-food Science and Technology Research Institute, Guangxi Academy of Agricultural Sciences, 174 East Daxue Road, 530007 Nanning, China
| | - Liang Shuai
- Agro-food Science and Technology Research Institute, Guangxi Academy of Agricultural Sciences, 174 East Daxue Road, 530007 Nanning, China
| | - Zhichun Li
- Agro-food Science and Technology Research Institute, Guangxi Academy of Agricultural Sciences, 174 East Daxue Road, 530007 Nanning, China
| | - Dongning Ling
- Agro-food Science and Technology Research Institute, Guangxi Academy of Agricultural Sciences, 174 East Daxue Road, 530007 Nanning, China
| | - Xuemei He
- Agro-food Science and Technology Research Institute, Guangxi Academy of Agricultural Sciences, 174 East Daxue Road, 530007 Nanning, China
| | - Fengjin Zheng
- Agro-food Science and Technology Research Institute, Guangxi Academy of Agricultural Sciences, 174 East Daxue Road, 530007 Nanning, China
| | - Guoming Liu
- Agro-food Science and Technology Research Institute, Guangxi Academy of Agricultural Sciences, 174 East Daxue Road, 530007 Nanning, China
| | - Yayuan Tang
- Agro-food Science and Technology Research Institute, Guangxi Academy of Agricultural Sciences, 174 East Daxue Road, 530007 Nanning, China
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5
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Kowluru A, Kowluru RA. RACking up ceramide-induced islet β-cell dysfunction. Biochem Pharmacol 2018; 154:161-169. [PMID: 29715450 DOI: 10.1016/j.bcp.2018.04.026] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 04/27/2018] [Indexed: 12/20/2022]
Abstract
The International Diabetes Federation predicts that by 2045 the number of individuals afflicted with diabetes will increase to 629 million. Furthermore, ∼352 million individuals with impaired glucose tolerance are at increased risk for developing diabetes. Several mechanisms have been proposed for the onset of metabolic dysfunction and demise of the islet β-cell leading to the pathogenesis of diabetes. It is widely accepted that the onset of type 2 diabetes is due to an intricate interplay between genetic expression of the disease and a multitude of factors including increased oxidative and endoplasmic reticulum stress consequential to glucolipotoxicity and inflammation. Compelling experimental evidence from in vitro and in vivo studies implicates intracellular generation of ceramide (CER), a biologically-active sphingolipid, as a trigger in the onset of β-cell demise under above pathological conditions. Recent pharmacological and molecular biological evidence affirms regulatory roles for Ras-related C3 botulinum toxin substrate 1 (Rac1), a small G protein, in the islet β-cell function in health and diabetes. In this Commentary, we overviewed the emerging evidence implicating potential cross-talk between Rac1 and ceramide signaling pathways in the onset of metabolic dysregulation of the islet β-cell culminating in impaired physiological insulin secretion, loss of β-cell mass and the onset of diabetes. Further, we propose a model depicting contributory roles of defective protein lipidation (prenylation) pathway in the induction of metabolic defects in the β-cell under metabolic stress conditions. Potential avenues for the identification of novel therapeutic targets for the prevention/treatment of diabetes and its associated complications are highlighted.
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Affiliation(s)
- Anjaneyulu Kowluru
- Biomedical Research Service, John D. Dingell VA Medical Center, Wayne State University, Detroit, MI 48201, USA; Department of Pharmaceutical Sciences, Wayne State University, Detroit, MI 48201, USA.
| | - Renu A Kowluru
- Department of Ophthalmology and Anatomy and Cell Biology, Wayne State University, Detroit, MI 48201, USA
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6
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Role of phospholipase D in the lifespan of Caenorhabditis elegans. Exp Mol Med 2018; 50:1-10. [PMID: 29622768 PMCID: PMC5938010 DOI: 10.1038/s12276-017-0015-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 12/01/2017] [Accepted: 12/05/2017] [Indexed: 11/08/2022] Open
Abstract
We have previously shown that phospholipase D (PLD) downregulation accelerates cellular senescence, which is widely believed to play an important role in aging, by stimulating reactive oxygen species (ROS) accumulation in human cells. In this study, we examined the role of PLD in aging using the nematode Caenorhabditis elegans. The mRNA level of pld-1 was found to be inversely correlated with aging. RNAi-mediated knockdown of pld-1 expression in nematodes enhanced ROS and lipofuscin accumulation and decreased lifespan, motility, and resistance to stress compared to that in nematodes treated with control RNAi. Pld-1 knockdown repressed the long lifespan of age-1 and akt-1 mutants but did not further reduce the short lifespan of daf-16 mutants, suggesting that PLD functions between AKT-1 and DAF-16. The ROS scavenger N-acetyl-L-cysteine, a PLD effector phosphatidic acid and a possible CK2 activator spermidine attenuated the lifespan shortening and age-related biomarkers triggered by pld-1 knockdown. Pld-1 RNAi downregulated the expression of DAF-16 target genes such as sod-3, dod-11, and mtl-1 in nematodes. In human cells, furthermore, PLD2 downregulation decreased the transcription of FoxO3a target genes (Cu/ZnSOD, MnSOD, catalase, thioredoxin-2, and peroxiredoxin-5), whereas ectopic PLD2 expression elevated the mRNA levels of these antioxidant genes. Taken together, these results indicated that PLD downregulation shortens longevity and induces age-related biomarkers through ROS accumulation by inhibiting the DAF-16/FoxO3a pathway in nematodes.
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7
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Lizardo DY, Lin YL, Gokcumen O, Atilla-Gokcumen GE. Regulation of lipids is central to replicative senescence. MOLECULAR BIOSYSTEMS 2017; 13:498-509. [PMID: 28128379 DOI: 10.1039/c6mb00842a] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Cellular replicative senescence, a state of permanent cell-cycle arrest, has been linked to organismal aging, tissue repair and tumorigenesis. In this study, we comparatively investigated the global lipid profiles and mRNA content of proliferating and senescent-state BJ fibroblasts. We found that both expression levels of lipid-regulating genes and the abundance of specific lipid families, are actively regulated. We further found that 19 specific polyunsaturated triacylglycerol species constituted the most prominent changes in lipid composition during replicative senescence. Based on the transcriptome analysis, we propose that the activation of CD36-mediated fatty acid uptake and diversion to glycerolipid biosynthesis could be responsible for the accumulation of triacylglycerols during replicative senescence. This, in turn, could be a cellular mechanism to prevent lipotoxicity under increased oxidative stress conditions observed in this process. Our results indicate that regulation of specific lipid species has a central role during replicative senescence.
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Affiliation(s)
- Darleny Y Lizardo
- Department of Chemistry, University at Buffalo, The State University of New York (SUNY), Buffalo, NY 14260 USA.
| | - Yen-Lung Lin
- Department of Biological Sciences, University at Buffalo, The State University of New York (SUNY), Buffalo, NY 14260 USA.
| | - Omer Gokcumen
- Department of Biological Sciences, University at Buffalo, The State University of New York (SUNY), Buffalo, NY 14260 USA.
| | - G Ekin Atilla-Gokcumen
- Department of Chemistry, University at Buffalo, The State University of New York (SUNY), Buffalo, NY 14260 USA.
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8
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Gomez-Cambronero J, Kantonen S. A river runs through it: how autophagy, senescence, and phagocytosis could be linked to phospholipase D by Wnt signaling. J Leukoc Biol 2014; 96:779-84. [PMID: 25082152 DOI: 10.1189/jlb.2vmr0214-120rr] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Neutrophils and macrophages are professional phagocytic cells, extremely efficient at the process of engulfing and killing bacteria. Autophagy is a similar process, by which phagosomes recycle internal cell structures during nutrient shortages. Some pathogens are able to subvert the autophagy process, funneling nutrients for their own use and for the host's detriment. Additionally, a failure to mount an efficient autophagy is a deviation on the cell's part from normal cellular function into cell senescence and cessation of the cell cycle. In spite of these reasons, the mechanism of autophagy and senescence in leukocytes has been under studied. We advance here the concept of a common thread underlying both autophagy and senescence, which implicates PLD. Such a PLD-based autophagy mechanism would involve two positive inputs: the generation of PA to help the initiation of the autophagosome and a protein-protein interaction between PLD and PKC that leads to enhanced PA. One negative input is also involved in this process: down-regulation of PLD gene expression by mTOR. Additionally, a dual positive/negative input plays a role in PLD-mediated autophagy, β-catenin increase of autophagy through PLD up-regulation, and a subsequent feedback termination by Dvl degradation in case of excessive autophagy. An abnormal PLD-mTOR-PKC-β-catenin/Wnt network function could lead to faulty autophagy and a means for opportunistic pathogens to survive inside of the cell.
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Affiliation(s)
- Julian Gomez-Cambronero
- Wright State University School of Medicine, Department of Biochemistry and Molecular Biology, Dayton, Ohio, USA
| | - Samuel Kantonen
- Wright State University School of Medicine, Department of Biochemistry and Molecular Biology, Dayton, Ohio, USA
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9
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Phospholipase D2 downregulation induces cellular senescence through a reactive oxygen species-p53-p21Cip1/WAF1
pathway. FEBS Lett 2014; 588:3251-8. [DOI: 10.1016/j.febslet.2014.07.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 07/11/2014] [Accepted: 07/11/2014] [Indexed: 11/23/2022]
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10
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Bae EJ, Lee HJ, Jang YH, Michael S, Masliah E, Min DS, Lee SJ. Phospholipase D1 regulates autophagic flux and clearance of α-synuclein aggregates. Cell Death Differ 2014; 21:1132-41. [PMID: 24632948 DOI: 10.1038/cdd.2014.30] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 01/29/2014] [Accepted: 01/30/2014] [Indexed: 01/18/2023] Open
Abstract
Many neurodegenerative diseases, such as Alzheimer's disease and Parkinson's disease, are characterized by abnormal accumulations of aggregated proteins. Brains in these diseases also show accumulation of autophagic vesicles in the neuronal cytoplasm, suggesting impairment of the autophagic process. As autophagy involves de novo membrane production and vesicle fusion, extensive changes in lipid molecules are necessary. However, the involvement of signaling lipid-modifying enzymes in autophagy and their roles in neurodegenerative diseases are not clear. Using specific inhibitor, we show that loss of phospholipase D1 (PLD1) activity resulted in an accumulation of microtubule-associated protein light chain 3 (LC3), p62, and polyubiquitinated proteins, signs representing malfunction in autophagic flux. Fluorescence and electron microscopic analyses demonstrated impaired fusion of autophagosomes with lysosomes, resulting in accumulation of autophagosomes. Within the cells with impaired autophagic flux, α-synuclein aggregates accumulated in autophagosomes. Knockdown of PLD1 expression using small interfering RNA also resulted in impaired autophagic flux and accumulation of α-synuclein aggregates in autophagosomes. Neuronal toxicity caused by α-synuclein accumulation was rescued by overexpression of PLD1; however, expression of activity-deficient mutant, PLD1-KRM, showed reduced rescue effects. Finally, we demonstrated that both PLD activity and expression levels were reduced in brain tissues of dementia with Lewy bodies (DLB) patients, whereas the amounts of α-synuclein and p62 were increased in the same tissue samples. Collectively, these results suggest that insufficient PLD activity, and therefore, the changes in phospholipid compositions within membranes, might be an important contributor to impaired autophagic process and protein accumulation in Lewy body diseases.
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Affiliation(s)
- E-J Bae
- 1] Department of Biomedical Science and Technology, Konkuk University, Seoul, Korea [2] IBST, Konkuk University, Seoul, Korea
| | - H-J Lee
- 1] IBST, Konkuk University, Seoul, Korea [2] Department of Anatomy, School of Medicine, Konkuk University, Seoul, Korea
| | - Y-H Jang
- Department of Molecular Biology, Pusan National University, Pusan, Korea
| | - S Michael
- Department of Neurosciences and Pathology, School of Medicine, University of California San Diego, La Jolla, CA, USA
| | - E Masliah
- Department of Neurosciences and Pathology, School of Medicine, University of California San Diego, La Jolla, CA, USA
| | - D S Min
- Department of Molecular Biology, Pusan National University, Pusan, Korea
| | - S-J Lee
- 1] Department of Biomedical Science and Technology, Konkuk University, Seoul, Korea [2] IBST, Konkuk University, Seoul, Korea
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11
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Gonzalez Pardo V, Russo de Boland A. Age-related changes in the response of intestinal cells to 1α,25(OH)2-vitamin D3. Ageing Res Rev 2013; 12:76-89. [PMID: 22706185 DOI: 10.1016/j.arr.2012.06.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 06/01/2012] [Accepted: 06/06/2012] [Indexed: 12/14/2022]
Abstract
The hormonally active form of vitamin D(3), 1α,25(OH)(2)-vitamin D(3), acts in intestine, its major target tissue, where its actions are of regulatory and developmental importance: regulation of intracellular calcium through modulation of second messengers and activation of mitogenic cascades leading to cell proliferation. Several causes have been postulated to modify the hormone response in intestinal cells with ageing, among them, alterations of vitamin D receptor (VDR) levels and binding sites, reduced expression of G-proteins and hormone signal transduction changes. The current review summarizes the actual knowledge regarding the molecular and biochemical basis of age-impaired 1α,25(OH)(2)-vitamin D(3) receptor-mediated signaling in intestinal cells. A fundamental understanding why the hormone functions are impaired with age will enhance our knowledge of its importance in intestinal cell physiology.
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Affiliation(s)
- Verónica Gonzalez Pardo
- Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Consejo Nacional de Investigaciones Científicas y Técnicas, Bahía Blanca, Argentina
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12
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Heffernan-Stroud LA, Helke KL, Jenkins RW, De Costa AM, Hannun YA, Obeid LM. Defining a role for sphingosine kinase 1 in p53-dependent tumors. Oncogene 2012; 31:1166-75. [PMID: 21765468 PMCID: PMC3278571 DOI: 10.1038/onc.2011.302] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2011] [Revised: 06/12/2011] [Accepted: 06/13/2011] [Indexed: 12/23/2022]
Abstract
p53 is a crucial tumor suppressor that is mutated or deleted in a majority of cancers. Exactly how p53 prevents tumor progression has proved elusive for many years; however, this information is crucial to define targets for chemotherapeutic development that can effectively restore p53 function. Bioactive sphingolipids have recently emerged as important regulators of proliferative, apoptotic and senescent cellular processes. In this study, we demonstrate that the enzyme sphingosine kinase 1 (SK1), a critical enzyme in the regulation of the key bioactive sphingolipids ceramide, sphingosine and sphingosine-1-phosphate (S1P), serves as a key downstream target for p53 action. Our results show that SK1 is proteolysed in response to genotoxic stress in a p53-dependent manner. p53 null mice display elevation of SK1 levels and a tumor-promoting dysregulation of bioactive sphingolipids in which the anti-growth sphingolipid ceramide is decreased and the pro-growth sphingolipid S1P is increased. Importantly, deletion of SK1 in p53 null mice completely abrogated thymic lymphomas in these mice and prolonged their life span by ~30%. Deletion of SK1 also significantly attenuated the formation of other cancers in p53 heterozygote mice. The mechanism of p53 tumor suppression by loss of SK1 is mediated by elevations of sphingosine and ceramide, which in turn were accompanied by increased expression of cell cycle inhibitors and tumor cell senescence. Thus, targeting SK1 may restore sphingolipid homeostasis in p53-dependent tumors and provide insights into novel therapeutic approaches to cancer.
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Affiliation(s)
- Linda A. Heffernan-Stroud
- Molecular and Cellular Biology and Pathobiology Program, Medical University of South Carolina, Charleston, SC 29403, USA
| | - Kristi L. Helke
- Department of Comparative Medicine/Lab Animal Resources, Medical University of South Carolina, Charleston, SC 29403, USA
| | - Russell W. Jenkins
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29403, USA
| | - Anna-Maria De Costa
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC 29403, USA
| | - Yusuf A. Hannun
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29403, USA
| | - Lina M. Obeid
- Ralph H. Johnson VAMC, Charleston, SC
- Molecular and Cellular Biology and Pathobiology Program, Medical University of South Carolina, Charleston, SC 29403, USA
- Department of Medicine, Medical University of South Carolina, Charleston, SC 29403, USA
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29403, USA
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13
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TNF-α- and tumor-induced skeletal muscle atrophy involves sphingolipid metabolism. Skelet Muscle 2012; 2:2. [PMID: 22257771 PMCID: PMC3344678 DOI: 10.1186/2044-5040-2-2] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 01/18/2012] [Indexed: 11/11/2022] Open
Abstract
Background Muscle atrophy associated with various pathophysiological conditions represents a major health problem, because of its contribution to the deterioration of patient status and its effect on mortality. Although the involvement of pro-inflammatory cytokines in this process is well recognized, the role of sphingolipid metabolism alterations induced by the cytokines has received little attention. Results We addressed this question both in vitro using differentiated myotubes treated with TNF-α, and in vivo in a murine model of tumor-induced cachexia. Myotube atrophy induced by TNF-α was accompanied by a substantial increase in cell ceramide levels, and could be mimicked by the addition of exogenous ceramides. It could be prevented by the addition of ceramide-synthesis inhibitors that targeted either the de novo pathway (myriocin), or the sphingomyelinases (GW4869 and 3-O-methylsphingomyelin). In the presence of TNF-α, ceramide-synthesis inhibitors significantly increased protein synthesis and decreased proteolysis. In parallel, they lowered the expression of both the Atrogin-1 and LC3b genes, involved in muscle protein degradation by proteasome and in autophagic proteolysis, respectively, and increased the proportion of inactive, phosphorylated Foxo3 transcription factor. Furthermore, these inhibitors increased the expression and/or phosphorylation levels of key factors regulating protein metabolism, including phospholipase D, an activator of mammalian target of rapamycin (mTOR), and the mTOR substrates S6K1 and Akt. In vivo, C26 carcinoma implantation induced a substantial increase in muscle ceramide, together with drastic muscle atrophy. Treatment of the animals with myriocin reduced the expression of the atrogenes Foxo3 and Atrogin-1, and partially protected muscle tissue from atrophy. Conclusions Ceramide accumulation induced by TNF-α or tumor development participates in the mechanism of muscle-cell atrophy, and sphingolipid metabolism is a logical target for pharmacological or nutritional interventions aiming at preserving muscle mass in pathological situations.
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Campos SGP, Gonçalves BF, Scarano WR, Corradi LS, Santos FCA, Custodio AMG, Vilamaior PSL, Góes RM, Taboga SR. Tissue changes in senescent gerbil prostate after hormone deprivation leads to acquisition of androgen insensitivity. Int J Exp Pathol 2010; 91:394-407. [PMID: 20353424 DOI: 10.1111/j.1365-2613.2010.00706.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The present study examined the response of the prostate epithelium of senescent gerbils submitted to orchiectomy and with or without steroidal blockade. Animals were divided into five groups, all surgically castrated except the control group composed of intact animals. In the experimental groups, doses of flutamide and/or tamoxifen were applied for 1, 3, 7 and 30 days postcastration. The structural methods applied reveal that castration, whether associated or not with anti-steroidal drugs, promoted short- and long-term decrease in wet and relative weights of the prostate. The quantitative decline of epithelial compartment proportion observed at the end of treatment was due to the sum of slight changes in the epithelium and lumen. The apoptotic index had risen significantly at 1 day and declined at 7 days postcastration. Androgen receptor (AR) expression decreased after 3 days of hormonal ablation, coinciding with the highest levels of apoptosis and cell proliferation observed in all treated groups. The majority of cells remained differentiated in all groups due to CK 8/18 expression. Some animals remained with injuries such as carcinomas and adenocarcinomas after hormonal ablation. In the latter a mixture of AR-positive and AR-negative cells was identified. Microinvasive carcinomas found in the group treated for 30 days consisted of PCNA-positive, inflammatory and non-proliferating cells. Low apoptosis incidence and bcl-2 positive cells were observed in these lesions. The treatments promoted a reduction of lesions in older gerbils, but treatment-resistant tumours will improve understanding of the events that lead to hormone resistance.
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Affiliation(s)
- Silvana G P Campos
- Laboratory of Microscopy and Microanalysis, Department of Biology, Institute of Biosciences, Humanities and Exact Sciences - IBILCE, São Paulo State University - UNESP, São José do Rio Preto, SP, Brazil
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15
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Regulation of phosphatidic Acid metabolism by sphingolipids in the central nervous system. J Lipids 2010; 2011:342576. [PMID: 21490799 PMCID: PMC3068476 DOI: 10.1155/2011/342576] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Accepted: 10/14/2010] [Indexed: 12/12/2022] Open
Abstract
This paper explores the way ceramide, sphingosine, ceramide 1-phosphate, and sphingosine 1-phosphate modulate the generation of second lipid messengers from phosphatidic acid in two experimental models of the central nervous system: in vertebrate rod outer segments prepared from dark-adapted retinas as well as in rod outer segments prepared from light-adapted retinas and in rat cerebral cortex synaptosomes under physiological aging conditions. Particular attention is paid to lipid phosphate phosphatase, diacylglycerol lipase, and monoacylglycerol lipase. Based on the findings reported in this paper, it can be concluded that proteins related to phototransduction phenomena are involved in the effects derived from sphingosine 1-phosphate/sphingosine or ceramide 1-phosphate/ceramide and that age-related changes occur in the metabolism of phosphatidic acid from cerebral cortex synaptosomes in the presence of either sphingosine 1-phosphate/sphingosine or ceramide 1-phosphate/ceramide. The present paper demonstrates, in two different models of central nervous system, how sphingolipids influence phosphatidic acid metabolism under different physiological conditions such as light and aging.
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16
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Gangoiti P, Camacho L, Arana L, Ouro A, Granado MH, Brizuela L, Casas J, Fabriás G, Abad JL, Delgado A, Gómez-Muñoz A. Control of metabolism and signaling of simple bioactive sphingolipids: Implications in disease. Prog Lipid Res 2010; 49:316-34. [PMID: 20193711 DOI: 10.1016/j.plipres.2010.02.004] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 02/18/2010] [Accepted: 02/22/2010] [Indexed: 01/05/2023]
Abstract
Simple bioactive sphingolipids include ceramide, sphingosine and their phosphorylated forms sphingosine 1-phosphate and ceramide 1-phosphate. These molecules are crucial regulators of cell functions. In particular, they play important roles in the regulation of angiogenesis, apoptosis, cell proliferation, differentiation, migration, and inflammation. Decoding the mechanisms by which these cellular functions are regulated requires detailed understanding of the signaling pathways that are implicated in these processes. Most importantly, the development of inhibitors of the enzymes involved in their metabolism may be crucial for establishing new therapeutic strategies for treatment of disease.
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Affiliation(s)
- Patricia Gangoiti
- Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Bilbao, Spain
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17
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Arana L, Gangoiti P, Ouro A, Trueba M, Gómez-Muñoz A. Ceramide and ceramide 1-phosphate in health and disease. Lipids Health Dis 2010; 9:15. [PMID: 20137073 PMCID: PMC2828451 DOI: 10.1186/1476-511x-9-15] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2009] [Accepted: 02/05/2010] [Indexed: 01/06/2023] Open
Abstract
Sphingolipids are essential components of cell membranes, and many of them regulate vital cell functions. In particular, ceramide plays crucial roles in cell signaling processes. Two major actions of ceramides are the promotion of cell cycle arrest and the induction of apoptosis. Phosphorylation of ceramide produces ceramide 1-phosphate (C1P), which has opposite effects to ceramide. C1P is mitogenic and has prosurvival properties. In addition, C1P is an important mediator of inflammatory responses, an action that takes place through stimulation of cytosolic phospholipase A2, and the subsequent release of arachidonic acid and prostaglandin formation. All of the former actions are thought to be mediated by intracellularly generated C1P. However, the recent observation that C1P stimulates macrophage chemotaxis implicates specific plasma membrane receptors that are coupled to Gi proteins. Hence, it can be concluded that C1P has dual actions in cells, as it can act as an intracellular second messenger to promote cell survival, or as an extracellular receptor agonist to stimulate cell migration.
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Affiliation(s)
- Lide Arana
- Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), PO Box 644, 48080 Bilbao, Spain
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18
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Kim NY, Kim TH, Lee E, Patra N, Lee J, Shin MO, Kwack SJ, Park KL, Han SY, Kang TS, Kim SH, Lee BM, Kim HS. Functional role of phospholipase D (PLD) in di(2-ethylhexyl) phthalate-induced hepatotoxicity in Sprague-Dawley rats. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2010; 73:1560-1569. [PMID: 20954081 DOI: 10.1080/15287394.2010.511582] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Phospholipase D (PLD) is an enzyme that catalyzes the hydrolysis of phosphatidyl choline (PC) to generate phosphatidic acid (PA) and choline. PLD is believed to play an important role in cell proliferation, survival signaling, cell transformation, and tumor progression. However, it remains to be determined whether enhanced expression of PLD in liver is sufficient to induce hepatotoxicity. The aim of this study was to investigate the possible role of PLD in di(2-ethylhexyl) phthalate (DEHP)-induced hepatotoxicity in Sprague-Dawley rats. The phthalate, DEHP (500 mg/kg/d), was administered orally, daily to prepubertal rats (4 wk of age, weighing approximately 70-90 g) for 1, 7, or 28 d. In this study, protein expression levels of PLD1/2, peroxisome proliferator-activated receptor (PPAR), and cytochrome P-450 (CYP) were determined by Western blot analysis using specific antibodies. Liver weight was significantly increased in the DEHP treatment groups. Immunohistochemical analysis demonstrated that DEHP produced strong staining of proliferating cell nuclear antigen (PCNA) at 28 d of exposure, suggestive of hepatocyte proliferation. A significant rise in PLD1/2 expression was observed in liver of DEHP-exposed rats after 7 d. Further, PPARα, constitutive androstane receptor (CAR), pregnane X receptor (PXR), and CYP2B1 protein expression levels were markedly elevated in DEHP-treated groups. Our results suggest that DEHP significantly enhanced the expression of PLD, which may be correlated with PPARα-induced hepatotoxicity through a complex interaction with nuclear receptors including CAR and PXR.
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Affiliation(s)
- Na Young Kim
- Laboratory of Molecular Toxicology, College of Pharmacy, Pusan National University, Busan, South Korea
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19
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Ceramide and cholesterol: possible connections between normal aging of the brain and Alzheimer's disease. Just hypotheses or molecular pathways to be identified? Alzheimers Dement 2009; 1:43-50. [PMID: 19595816 DOI: 10.1016/j.jalz.2005.06.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Even though it is known that aging is the single most important risk factor for Alzheimer's disease (AD), there is a lack of information on the molecular pathway(s) that connect normal aging of the brain to this form of neuropathology. Because of the rise in average lifespan, the number of individuals that reach the seventh or eighth decade of life and become at high risk for AD is rapidly increasing. Current estimations predict that by 2050 about 45 to 50 million individuals will be affected by AD worldwide. Here, we discuss the need for more age-directed research to understand AD neuropathology. We also elaborate on the possible role of cholesterol and ceramide as molecular connections between aging and AD, and as novel therapeutic targets for the prevention of late-onset AD.
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20
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Tuder RM, Yun JH, Graham BB. Cigarette smoke triggers code red: p21CIP1/WAF1/SDI1 switches on danger responses in the lung. Am J Respir Cell Mol Biol 2008; 39:1-6. [PMID: 18441278 DOI: 10.1165/rcmb.2008-0117tr] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The article by Yao and coworkers in this issue (Am. J. Respir. Cell Mol. Biol. 2008;39:7-18) reveals that the cyclin-dependent kinase inhibitor p21CIP1/WAF1/SDI1 (designated hereafter as p21), which has been linked to cell cycle growth arrest due to stress or danger cell responses, may modulate alveolar inflammation and alveolar destruction, and thus enlightens our present understanding of how the lung senses injury due to cigarette smoke and integrates these responses with those that activate inflammatory pathways potentially harmful to the lung. Furthermore, the interplay of p21 and cellular processes involving cell senescence and the imbalance of cell proliferation/apoptosis may provide us with a more logical explanation of how p21, acting as a sensor of cellular stress, might have such potent and wide roles in lung responses triggered by cigarette smoke. Molecular switches, ontologically designed for the protection of the host, are now hijacked by injurious stresses (such as cigarette smoke), leading to organ damage.
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Affiliation(s)
- Rubin M Tuder
- Division of Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado Denver, School of Medicine, 4200 East 9th Avenue, Campus Box C272, Denver, CO 80262, USA.
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21
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Campos SGP, Zanetoni C, Scarano WR, Vilamaior PSL, Taboga SR. Age-related histopathological lesions in the Mongolian gerbil ventral prostate as a good model for studies of spontaneous hormone-related disorders. Int J Exp Pathol 2008; 89:13-24. [PMID: 18197870 DOI: 10.1111/j.1365-2613.2007.00550.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The Meriones unguiculatus (Mongolian) gerbil has demonstrated significant prostatic responses to hormonal treatments, and to drugs against human prostatic hyperplasia. Spontaneous neoplasia develops in the older animals. Thirty gerbils (age 18 months) were divided into non-affected and prostatic lesion bearers and the prostate lesions were evaluated morphologically, immunohistochemically and quantitatively. The most frequent changes were in epithelial sites and, namely prostatic intraepithelial neoplasias, microinvasive carcinomas and adenocarcinomas. In the stromal compartment, cellular hyperplasia, when verified, was always associated with the sites of anomalous epithelium. Additionally, larger deposition of collagen fibrils, generating stromal fibrosis, was found in all the old gerbils analysed. The quantitative analysis showed that prostatic tissue proportions differed in altered areas, being specific for each lesion type. Isolated nuclear and nucleolar parameters were not effective in diagnosing the malign potential of lesions. However, the cellular proliferation and death indexes indicated larger cellular turnover in invasive lesions such as carcinomas. With these analyses, it could be verified that old gerbils present high propensity to develop spontaneous prostate changes and this may aid in a better understanding of the biological behaviour of human prostate cancer.
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22
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Martín SF, Sawai H, Villalba JM, Hannun YA. Redox regulation of neutral sphingomyelinase-1 activity in HEK293 cells through a GSH-dependent mechanism. Arch Biochem Biophys 2007; 459:295-300. [PMID: 17169322 DOI: 10.1016/j.abb.2006.11.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Revised: 11/08/2006] [Accepted: 11/09/2006] [Indexed: 10/23/2022]
Abstract
Phospholipases are essential enzymes in cellular signalling processes such as cellular differentiation, proliferation and apoptosis. Based on its high degree of homology with sequences of prokaryote SMases, a type of Mg(2+)-dependent PLC (nSMase-1) was recently discovered which displayed strong redox dependence for activity in vitro [F. Rodrigues-Lima, A.C. Fensome, M. Josephs, J. Evans, R.J. Veldman, M. Katan (2000), J. Biol. Chem. 275 (36) 28316-28325]. The aim of this work was to test the hypothesis that glutathione could be a natural regulator of nSMase-1 activity ex vivo. We studied how altering glutathione levels and redox ratio modulate nSMase-1 activity in a HEK293 cell line that ectopically overexpressed the nSMase-1 gene. Diminishing total glutathione with BSO without altering significantly the GSH/GSSG ratio did not affect nSMase-1 activity. Treatment of cells with diamide produced a transient decrease of total glutathione and a sharp, but also transient, decrease of the GSH/GSSG ratio. Under these conditions, nSMase-1 activity was temporarily activated and then returned to normal levels. Simultaneous treatment with BSO and diamide that resulted in permanent decreases of total glutathione and GSH/GSSG redox ratio produced a sustained activation of nSMase-1 activity. Taken together, these data indicate that altering the GSH/GSSG ratio by increasing GSSG or decreasing GSH levels, but not the total concentration of glutathione, modulates nSMase-1 activity. Our findings are the first evidence supporting the ex vivo regulation of nSMase-1 through a redox glutathione-dependent mechanism.
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Affiliation(s)
- Sergio F Martín
- Departamento de Biología Celular, Fisiología e Inmunología, Facultad de Ciencias, Universidad de Córdoba, 14071 Córdoba, Spain.
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23
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Puglielli L. Aging of the brain, neurotrophin signaling, and Alzheimer's disease: is IGF1-R the common culprit? Neurobiol Aging 2007; 29:795-811. [PMID: 17313996 PMCID: PMC2387053 DOI: 10.1016/j.neurobiolaging.2007.01.010] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Revised: 09/21/2006] [Accepted: 01/13/2007] [Indexed: 12/26/2022]
Abstract
The last decade has revealed that the lifespan of an organism can be modulated by the signaling pathway that acts downstream of the insulin/insulin-like growth factor 1 receptors (IR/IGF1-R), indicating that there is a "program" that drives the process of aging. New results have now linked the same pathway to the neurogenic capacities of the aging brain, to neurotrophin signaling, and to the molecular pathogenesis of Alzheimer's disease. Therefore, a common signaling cascade now seems to link aging to age-associated pathologies of the brain, suggesting that pharmacologic approaches aimed at the modulation of this pathway can serve to delay the onset of age-associated disorders and improve the quality of life. Work from a wide range of fields performed with different approaches has already identified some of the signaling molecules that act downstream of IGF1-R, and has revealed that a delicate checkpoint exists to balance excessive growth/"immortality" and reduced growth/"senescence" of a cell. Future research will determine how far the connection goes and how much of it we can influence.
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Affiliation(s)
- Luigi Puglielli
- Department of Medicine, University of Wisconsin-Madison, and Geriatric Research Education Clinical Center, VA Medical Center, VAH-GRECC 11G, 2500 Overlook Terrace, Madison, WI 53705, USA.
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Mebarek S, Komati H, Naro F, Zeiller C, Alvisi M, Lagarde M, Prigent AF, Némoz G. Inhibition of de novo ceramide synthesis upregulates phospholipase D and enhances myogenic differentiation. J Cell Sci 2007; 120:407-16. [PMID: 17213336 DOI: 10.1242/jcs.03331] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In L6 skeletal myoblasts induced to differentiate by Arg8-vasopressin treatment, a short-lived lowering of ceramide levels was observed, followed by a long-lasting elevation that was prevented by inhibitors of the de novo synthesis pathway, fumonisin B1 and myriocin. Both inhibitors increased the expression of myogenic differentiation markers and cell fusion rate, whereas short-chain ceramides inhibited these responses. Similar drug effects were observed on primary mouse satellite cell differentiation. Furthermore, bacterial sphingomyelinase overexpression suppressed myogenin nuclear accumulation in L6 cells. These data suggested that endogenous ceramide mediates a negative feedback mechanism limiting myogenic differentiation, and that inhibitors of ceramide synthesis promoted myogenesis by removing this control. Phospholipase D (PLD), a recognized target of ceramide, is required for myogenesis, as shown by the negative effects of PLD1 isoform depletion obtained by siRNA treatment. Fumonisin induced an increase in PLD activity of L6 cells, whereas C6-ceramide decreased it. The expression of PLD1 mRNA transcripts was selectively decreased by C6-ceramide, and increased by ceramide synthesis inhibitors. An early step of myogenic response is the PLD1-dependent formation of actin stress fiber-like structures. C6-ceramide addition or overexpression of sphingomyelinase impaired actin fiber formation. Ceramide might thus regulate myogenesis through downregulation of PLD1 expression and activity.
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25
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Wascholowski V, Giannis A. Sphingolactones: Selective and Irreversible Inhibitors of Neutral Sphingomyelinase. Angew Chem Int Ed Engl 2006; 45:827-30. [PMID: 16365835 DOI: 10.1002/anie.200501983] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Veit Wascholowski
- University of Leipzig, Institute of Organic Chemistry, 04103 Leipzig, Germany
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26
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Wascholowski V, Giannis A. Sphingolactone: selektive und irreversibel wirkende Inhibitoren der neutralen Sphingomyelinase. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200501983] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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27
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Costantini C, Weindruch R, Della Valle G, Puglielli L. A TrkA-to-p75NTR molecular switch activates amyloid beta-peptide generation during aging. Biochem J 2006; 391:59-67. [PMID: 15966860 PMCID: PMC1237139 DOI: 10.1042/bj20050700] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Aging is the single most important risk factor for AD (Alzheimer's disease). However, the molecular events that connect normal aging to AD are mostly unknown. The abnormal accumulation of Abeta (amyloid beta-peptide) in the form of senile plaques is one of the main characteristics of AD. In the present study, we show that two members of the neurotrophin receptor superfamily, TrkA (tyrosine kinase receptor A) and p75NTR (p75 neurotrophin receptor), differentially regulate the processing of APP (amyloid precursor protein): TrkA reduces, whereas p75NTR activates, beta-cleavage of APP. The p75NTR-dependent effect requires NGF (nerve growth factor) binding and activation of the second messenger ceramide. We also show that normal aging activates Abeta generation in the brain by 'switching' from the TrkA to the p75NTR receptor system. Such an effect is abolished in p75NTR 'knockout' animals, and can be blocked by both caloric restriction and inhibitors of nSMase (neutral sphingomyelinase). In contrast with caloric restriction, which prevents the age-associated up-regulation of p75NTR expression, nSMase inhibitors block the activation of ceramide. When taken together, these results indicate that the p75NTR-ceramide signalling pathway activates the rate of Abeta generation in an age-dependent fashion, and provide a new target for both the understanding and the prevention of late-onset AD.
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Affiliation(s)
- Claudio Costantini
- *Department of Medicine, University of Wisconsin-Madison, Wm. S. Middleton Memorial Veteran's Hospital, Madison, WI 53705, U.S.A
| | - Richard Weindruch
- *Department of Medicine, University of Wisconsin-Madison, Wm. S. Middleton Memorial Veteran's Hospital, Madison, WI 53705, U.S.A
| | | | - Luigi Puglielli
- *Department of Medicine, University of Wisconsin-Madison, Wm. S. Middleton Memorial Veteran's Hospital, Madison, WI 53705, U.S.A
- To whom correspondence should be addressed (email )
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Jensen JM, Förl M, Winoto-Morbach S, Seite S, Schunck M, Proksch E, Schütze S. Acid and neutral sphingomyelinase, ceramide synthase, and acid ceramidase activities in cutaneous aging. Exp Dermatol 2005; 14:609-18. [PMID: 16026583 DOI: 10.1111/j.0906-6705.2005.00342.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In aged skin, decreased levels of stratum corneum ceramides have been described. Epidermal ceramides are generated by sphingomyelin hydrolysis or synthesis from sphingosin and fatty acids and are degraded by ceramidase. We recently showed that epidermal acid sphingomyelinase (A-SMase) generates ceramides with structural function in the stratum corneum lipid bilayers, which provide for the permeability barrier function of the skin. Here, we examined the activities of epidermal A-SMase, ceramide synthase, and ceramidase in chronologically aged versus young hairless mouse skin. We found reduced A-SMase and ceramide synthase activities in the epidermis of aged mice. However, studies on enzyme localization revealed unchanged, ongoing high A-SMase activity in the outer epidermis, which correlated with reported normal barrier function found in aged skin under basal conditions. Reduced A-SMase and ceramide synthase activity was noted in the inner epidermis, correlating with reduced capacity for permeability barrier repair in aging. Ceramidase activity was not age dependent. In summary, we found reduced activities of ceramide-generating SMase and ceramide synthase in the inner epidermis of aged skin, explaining its reduced capacity in barrier repair. In contrast, A-SMase activity in the outer epidermis was unchanged, indicating that this enzyme is crucially involved in basal permeability barrier homeostasis.
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Abstract
Ten years after the isoforms of mammalian phospholipase D (PLD), PLD1 and 2, were cloned, their roles in the brain remain speculative but several lines of evidence now implicate these enzymes in basic cell functions such as vesicular trafficking as well as in brain development. Many mitogenic factors, including neurotransmitters and growth factors, activate PLD in neurons and astrocytes. Activation of PLD downstream of protein kinase C seems to be a required step for astroglial proliferation. The characteristic disruption of the PLD signaling pathway by ethanol probably contributes to the delay of brain growth in fetal alcohol syndrome. The post-natal increase of PLD activities concurs with synapto- and myelinogenesis in the brain and PLD is apparently involved in neurite formation. In the adult and aging brain, PLD activity has antiapoptotic properties suppressing ceramide formation. Increased PLD activities in acute and chronic neurodegeneration as well as in inflammatory processes are evidently due to astrogliosis and may be associated with protective responses of tissue repair and remodeling. ARF-regulated PLD participates in receptor endocytosis as well as in exocytosis of neurotransmitters where PLD seems to favor vesicle fusion by modifications of the shape and charge of lipid membranes. Finally, PLD activities contribute free choline for the synthesis of acetylcholine in the brain. Novel tools such as RNA interference should help to further elucidate the roles of PLD isoforms in brain physiology and pathology.
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Affiliation(s)
- Jochen Klein
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Science Center, Amarillo, Texas 79106, USA.
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Manguikian AD, Barbour SE. Cell Cycle Dependence of Group VIA Calcium-independent Phospholipase A2 Activity. J Biol Chem 2004; 279:52881-92. [PMID: 15385540 DOI: 10.1074/jbc.m410659200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Homeostasis of phosphatidylcholine (PC) is regulated by the opposing actions between CTP:phosphocholine cytidylyltransferase (CT) and the group VIA Ca(2+)-independent phospholipase A(2) (iPLA(2)). We investigated this process during the cell cycle. PC mass doubles during late G(1) and early S phase when its rate of catabolism is lowest. We show that iPLA(2) activity is cell cycle-dependent with peak activity during G(2)/M and late S phase. iPLA(2) activity declines during G(1) and is lowest at the G(1)/S transition and early S phase. The accumulation of PC correlates with decreased iPLA(2) activity, suggesting that regulation of this enzyme contributes to phospholipid accumulation. The levels of 80 kDa iPLA(2) protein do not change and thus cannot account for changes in enzyme activity. Reverse transcriptase and real-time PCR experiments show that splice variant iPLA(2) mRNAs are preferentially expressed during G(2)/M. Immunoblot analyses with an antibody directed against the N terminus of iPLA(2) revealed a approximately 50 kDa protein that is of appropriate size to be the truncated protein encoded by the ankyrin-iPLA(2)-1 splice variant mRNA. The levels of truncated iPLA(2) protein were high in cells in late G(1) and S phase cells that had low iPLA(2) activity and low in G(2)/M cells that had high iPLA(2) activity. The truncated protein co-immunoprecipitated with full-length iPLA(2), indicating a physical interaction between the two proteins. Together, these data suggest that truncated iPLA(2) proteins associate with active iPLA(2) and down-regulate its activity during G(1). This down-regulation may contribute to phospholipid accumulation during the cell cycle.
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Affiliation(s)
- Alex D Manguikian
- Department of Biochemistry, Virginia Commonwealth University, Richmond, VA 23298-0614, USA
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31
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Riebeling C, Müller C, Geilen CC. Expression and regulation of phospholipase D isoenzymes in human melanoma cells and primary melanocytes. Melanoma Res 2004; 13:555-62. [PMID: 14646617 DOI: 10.1097/00008390-200312000-00003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Phospholipase D (PLD) is a highly regulated enzyme involved in lipid-mediated signal transduction processes affecting vesicular trafficking and cytoskeletal reorganization. It is regulated by protein kinase C, adenosine diphosphate (ADP)-ribosylation factors and Rho family proteins, and both protein kinase C and Rho family proteins have been implicated in the metastatic potential of melanoma. We analysed PLD in four human melanoma cell lines and in primary human melanocytes. Melanoma cell lines showed phosphatidylcholine-hydrolysing, phosphatidylinositol 4,5-bisphosphate-dependent PLD activity, which was activated by phorbol ester and a non-hydrolysable guanosine triphosphate (GTP) analogue in a dose-dependent and synergistic manner, whereas primary melanocytes exhibited only low PLD activity compared with the melanoma cell lines. As determined by reverse transcription polymerase chain reaction, both splicing variants of PLD1, PLD1a and PLD1b, and the isoenzyme PLD2, are expressed in melanoma cells and melanocytes. Western blot analysis showed that PLD1 expression was low in primary melanocytes in contrast to melanoma cells, which is in agreement with our finding of low activity. Interestingly, Rho protein mRNA was elevated in all melanoma cell lines. We conclude that in human melanoma cells, the PLD activity that is stimulated by phorbol ester requires ADP-ribosylation factor, protein kinase C and Rho proteins for full activity, and most probably represents the isoenzyme PLD1.
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Affiliation(s)
- Christian Riebeling
- Department of Dermatology, University Medical Center Benjamin Franklin, The Free University of Berlin, Germany
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32
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Payton JE, Perrin RJ, Woods WS, George JM. Structural Determinants of PLD2 Inhibition by α-Synuclein. J Mol Biol 2004; 337:1001-9. [PMID: 15033366 DOI: 10.1016/j.jmb.2004.02.014] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2003] [Revised: 12/02/2003] [Accepted: 02/05/2004] [Indexed: 11/26/2022]
Abstract
The presynaptic protein alpha-synuclein has been implicated in both neuronal plasticity and neurodegenerative disease, but its normal function remains unclear. We described the induction of an amphipathic alpha-helix at the N terminus (exons 2-4) of alpha-synuclein upon exposure to phospholipid vesicles, and hypothesized that lipid-binding might serve as a functional switch by stabilizing alpha-synuclein in an active (alpha-helical) conformation. Others have shown that alpha and beta-synucleins inhibit phospholipase D (PLD), an enzyme involved in lipid-mediated signaling cascades and vesicle trafficking. Here, we report that all three naturally occurring synuclein isoforms (alpha, beta, and gamma-synuclein) are similarly effective inhibitors of PLD2 in vitro, as is the Parkinson's disease-associated mutant A30P. The PD-associated mutant A53T, however, is a more potent inhibitor of PLD2 than is wild-type alpha-synuclein. We analyze mutations of the alpha-synuclein protein to identify critical determinants of human PLD2 inhibition in vitro. Deletion of residues 56-102 (exon 4) decreases PLD2 inhibition significantly; this activity of exon 4 may require adoption of an alpha-helical conformation, as mutations that disrupt alpha-helicity also abrogate inhibition. Deletion of C-terminal residues 130-140 (exon 6) completely abolishes inhibitory activity. In addition, PLD2 inhibition is blocked by phosphorylation at serine 129 or at tyrosine residues 125 and 136, or by mutations that mimic phosphorylation at these sites. We conclude that PLD2 inhibition by alpha-synuclein is mediated by a lipid-stabilized alpha-helical structure in exon 4 and also by residues within exon 6, and that this inhibition can be modulated by phosphorylation of specific residues in exons 5 and 6.
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Affiliation(s)
- Jacqueline E Payton
- Department of Molecular and Integrative Physiology, University of Illinois, Urbana, IL 61801, USA
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Puglielli L, Ellis BC, Saunders AJ, Kovacs DM. Ceramide stabilizes beta-site amyloid precursor protein-cleaving enzyme 1 and promotes amyloid beta-peptide biogenesis. J Biol Chem 2003; 278:19777-83. [PMID: 12649271 DOI: 10.1074/jbc.m300466200] [Citation(s) in RCA: 201] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The lipid second messenger ceramide regulates several biochemical events that occur during aging. In addition, its level is highly elevated in the amyloid-burdened brains of Alzheimer's disease patients. Here, we analyzed the impact of aberrant ceramide levels on amyloid beta-peptide (Abeta) generation by using a cell-permeable analog of ceramide, C6-ceramide, and several biochemical inhibitors of the sphingomyelin/glycosphingolipid biosynthetic pathway. We found that C6-ceramide increased the biogenesis of Abeta by affecting beta-but not gamma-cleavage of the amyloid precursor protein. Similarly to C6-ceramide, increased levels of endogenous ceramide induced by neutral sphingomyelinase treatment also promoted the biogenesis of Abeta. Conversely, fumonisin B1, which inhibits the biosynthesis of endogenous ceramide, reduced Abeta production. Exogenous C6-ceramide restored both intracellular ceramide levels and Abeta generation in fumonisin B1-treated cells. These events were specific for amyloid precursor protein and were not associated with apoptotic cell death. Pulse-chase and time-course degradation experiments showed that ceramide post-translationally stabilizes the beta-secretase BACE1. Taken together, these data indicate that the lipid second messenger ceramide, which is elevated in the brains of Alzheimer's disease patients, increases the half-life of BACE1 and thereby promotes Abeta biogenesis.
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Affiliation(s)
- Luigi Puglielli
- Neurobiology of Disease Laboratory, Massachusetts General Hospital, Harvard Medical School, Charlestown 02129, USA.
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34
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Jang IS, Yeo EJ, Park JA, Ahn JS, Park JS, Cho KA, Juhnn YS, Park SC. Altered cAMP signaling induced by lysophosphatidic acid in senescent human diploid fibroblasts. Biochem Biophys Res Commun 2003; 302:778-84. [PMID: 12646237 DOI: 10.1016/s0006-291x(03)00262-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Lysophosphatidic acid (LPA) is a lipid mitogen that acts through G-protein-coupled receptors. LPA responsiveness has been reported to be dependent on the senescent state of the cells. To solve the mechanism underlying, we observed LPA-dependent cAMP status and found its age-dependent contrasting profile such as high level of cAMP in the senescent cells vs its low level in the young cells. In order to clarify the molecular mechanism of the ageing effect, we examined various molecular species involved in the cAMP signaling pathway by semi-quantitative RT-PCR. EDG-1 and EDG-4 were unchanged, but EDG-2 and EDG-7 were reduced with age. Senescent cells showed a partial reduction of Gi1, Gi2, and Gi3, but no change in the level of Gq. Decreased Gis and Gi-coupled LPA receptors may reduce the inhibitory effect of Gi alpha on adenylyl cyclases (ACs), resulting in cAMP accumulation via activation of adenylyl cyclase in senescent fibroblasts. We also observed an age-dependent increase in some of AC isoforms: II, IV, and VI. In conclusion, multiple changes in the cAMP signaling pathway of the senescent cells might explain the altered responsiveness to the mitogenic stimuli.
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Affiliation(s)
- Ik-Soon Jang
- Department of Biochemistry, Seoul National University College of Medicine, 28 Yon-gon-Dong, Chongno-Gu, 110-799, Seoul, Republic of Korea
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35
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Gomez-Cambronero J, Horwitz J, Sha’afi RI. Measurements of phospholipases A2, C, and D (PLA2, PLC, and PLD). In vitro microassays, analysis of enzyme isoforms, and intact-cell assays. Methods Mol Biol 2003; 218:155-76. [PMID: 12616720 PMCID: PMC3070601 DOI: 10.1385/1-59259-356-9:155] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
In order to be properly divisible, the cell membrane has to be remodeled and intracellular membranes must be converted into a vesiculated state prior to mitosis. Phospholipases A2, C, and D (PLA2, PLC, and PLD) are involved in regulatory events of intracellular mitogen signaling pathways. We describe here three methods for comprehensively assaying those phospholipases: 1) in vitro microassays, in which a radiolabeled substrate is exogenously added to cell lysates to measure the enzyme activity(ies); 2) immunocomplex assays, in which immunoprecipitation with a specific antibody is performed in order to study the contribution of a particular isoform within a family of enzymes; and 3) intact-cell or in vivo assays, in which cells are labeled with a radioactive substrate until steady state is reached. The uniqueness of the in vitro microassay method described here for the first time is that it allows the measurement of, in parallel, the activities of three phospholipases utilizing aliquots derived from the same biological sample. The approach for immunoprecipitation described in this chapter can be extrapolated to the study of a large array of enzyme isoforms. Finally, the intact-cell assays allow for the accurate measurement of receptor-mediated activation in vivo.
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Affiliation(s)
- Julian Gomez-Cambronero
- Department of Physiology and Biophysics, Wright State University School of Medicine, Dayton, OH 45435
- Corresponding author: Department of Physiology & Biophysics, Wright State University School of Medicine, 3640 Colonel Glenn Highway, Dayton, OH 45435,
| | - Joel Horwitz
- Department of Pharmacology and Physiology, MCP Hahnemann University, Philadelphia, PA 19102
| | - Ramadan I. Sha’afi
- Department of Physiology, University of Connecticut Health Center, Farmington, CT 06030
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Yeo EJ, Park SC. Age-dependent agonist-specific dysregulation of membrane-mediated signal transduction: emergence of the gate theory of aging. Mech Ageing Dev 2002; 123:1563-78. [PMID: 12470894 DOI: 10.1016/s0047-6374(02)00092-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Although a general mechanism for the limited responsiveness of senescent cells has yet to be established, reduced responsiveness may in part be ascribed to deficits in the apparatus required for cell surface receptor-mediated signal transduction. Age-related changes of receptor-mediated signal transduction occur at many levels, and are known to include quantitative and qualitative changes in growth factor receptors, G-protein coupled receptors, and many other downstream signaling molecules. Here, we emphasize the prime role of the cellular surface in the perception and transmission of external stimuli in response to the aging process. As major means of cellular signal transduction, the receptor tyrosine kinase (RTK) system and the G protein-coupled receptor (GPCR) system of senescent cells were investigated. We observed that the RTK system was severely damaged, while the GPCR system was only partially inactivated by aging. These results suggest that the agonist-dependent dysregulation of and imbalance of signal transduction pathways might be responsible for the functional deterioration of senescent cells, and indicate a possibility of the functional recovery of senescent cells through agonist-specific signal system activation. Moreover, those data evoke the emerging concept that the senescent phenotype may be modulated by the membrance-associated signal system, implying the gate theory of aging.
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Affiliation(s)
- Eui-Ju Yeo
- Department of Biochemistry, Gachon Medical School, Inchon 417-840, South Korea.
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Hannun YA, Obeid LM. The Ceramide-centric universe of lipid-mediated cell regulation: stress encounters of the lipid kind. J Biol Chem 2002; 277:25847-50. [PMID: 12011103 DOI: 10.1074/jbc.r200008200] [Citation(s) in RCA: 664] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Yusuf A Hannun
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
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38
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Yeo EJ, Jang IS, Lim HK, Ha KS, Park SC. Agonist-specific differential changes of cellular signal transduction pathways in senescent human diploid fibroblasts. Exp Gerontol 2002; 37:871-83. [PMID: 12086695 DOI: 10.1016/s0531-5565(02)00027-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Changes in the signal transduction efficiency of senescent cells led us to compare the signaling events induced by two mitogenic agonists, platelet-derived growth factor (PDGF) and lysophosphatidic acid (LPA) in presenescent and senescent or near-senescent human diploid fibroblasts. When the changes in intracellular [Ca(2+)](i) were analyzed, both PDGF and LPA generated a rhythmic increase in [Ca(2+)](i) in presenescent cells. The frequency of calcium response was reduced and desensitized in PDGF-stimulated senescent cells, while response to a LPA-induced calcium signal was also reduced in frequency, though its magnitude was unaltered. PDGF treatment increased the fibrous actin (F-actin) level in presenescent cells but not in senescent cells in contrast to a reduced but visible increase in F-actin in LPA-treated senescent cells. The effect of PDGF on phospholipase D (PLD) activation was also reduced significantly, as a ca. 60-80% reduction of PLD activity was observed in PDGF-stimulated cells but only a little reduction in LPA-induced cells. Agonist-specific differential changes of cellular signaling events caused a differential effect on DNA synthesis after growth factor stimulation. We observed a dramatic (80-90%) reduction of [3H]thymidine incorporation into DNA in the PDGF-stimulated near-senescent cells. LPA resulted in a 2-3-fold increase in thymidine incorporation even in the near-senescent cells. These differences in the responses of senescent or near-senescent cells to PDGF- and LPA-stimulation raised questions about the differential changes of the respective signaling apparatuses induced by aging. Since PDGF signaling event was affected greatly by aging, we further examined the protein contents involved in PDGF signal transduction pathway. PDGF receptor (PDGFR), protein kinase C-alpha (PKC-alpha), phospholipase C-gamma1 (PLC-gamma1), and PLD1 were examined by Western blot analysis. The protein levels of PKC-alpha and PLC-gamma1 were unchanged, but those of PLD1 and PDGFR were reduced with age. The reduced content of PDGFR protein may be one of the important contributors to the failure of PDGF-stimulated signal transduction in human senescent fibroblasts. Our results strongly suggest that age-dependent agonist-specific changes in signaling events might be in charge of the functional deterioration of senescent cells through imbalance of signal responses.
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Affiliation(s)
- Eui-Ju Yeo
- Department of Biochemistry, Gachon Medical School, Inchon 417-840, South Korea
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39
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Ogretmen B, Pettus BJ, Rossi MJ, Wood R, Usta J, Szulc Z, Bielawska A, Obeid LM, Hannun YA. Biochemical mechanisms of the generation of endogenous long chain ceramide in response to exogenous short chain ceramide in the A549 human lung adenocarcinoma cell line. Role for endogenous ceramide in mediating the action of exogenous ceramide. J Biol Chem 2002; 277:12960-9. [PMID: 11815611 DOI: 10.1074/jbc.m110699200] [Citation(s) in RCA: 335] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Treatment of A549 cells with C(6)-ceramide resulted in a significant increase in the endogenous long chain ceramide levels, which was inhibited by fumonisin B1 (FB1), and not by myriocin (MYR). The biochemical mechanisms of generation of endogenous ceramide were investigated using A549 cells treated with selectively labeled C(6)-ceramides, [sphingosine-3-(3)H]d-erythro-, and N-[N-hexanoyl-1-(14)C]d-erythro-C(6)-ceramide. The results demonstrated that (3)H label was incorporated into newly synthesized long chain ceramides, which was inhibited by FB1 and not by MYR. Interestingly, the (14)C label was not incorporated into long chain ceramides. Taken together, these results show that generation of endogenous ceramide in response to C(6)-ceramide is due to recycling of the sphingosine backbone of C(6)-ceramide via deacylation/reacylation and not due to the elongation of its fatty acid moiety. Moreover, the generation of endogenous long chain ceramide in response to C(6)-ceramide was completely blocked by brefeldin A, which causes Golgi disassembly, suggesting a role for the Golgi in the metabolism of ceramide. In addition, the generation of endogenous ceramide in response to short chain exogenous ceramide was induced by d-erythro- but not l-erythro-C(6)-ceramide, demonstrating the stereospecificity of this process. Interestingly, several key downstream biological activities of ceramide, such as growth inhibition, cell cycle arrest, and modulation of telomerase activity were induced by d-erythro-C(6)-ceramide, and not l-erythro-C(6)-ceramide (and inhibited by FB1) in A549 cells, suggesting a role for endogenous long chain ceramide in the regulation of these responses.
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Affiliation(s)
- Besim Ogretmen
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA.
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40
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Throckmorton D, Kurscheid-Reich D, Rosales OR, Rodriguez-Commes J, Lopez R, Sumpio B, Zhong Q, Ding KH, McCarthy R, Barrett PQ, Isales CM. Parathyroid hormone effects on signaling pathways in endothelial cells vary with peptide concentration. Peptides 2002; 23:79-85. [PMID: 11814621 DOI: 10.1016/s0196-9781(01)00582-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We have previously reported that parathyroid hormone (PTH) has specific effects on a human umbilical vein endothelial cell line. Further studies were performed to characterize the signaling cascades initiated by PTH. We report that PTH induced the appearance of voltage sensitive calcium channels. Furthermore, PTH increased ceramide but not diacylglycerol content. Since elevations in [Ca(2+)](i) and phospholipid turnover are signals for the activation of protein kinase C (PKC), the cells were screened for PKC isoforms. PTH induced a redistribution of the PKCepsilon to the particulate fractions of cell homogenates. In summary, PTH induced PKC translocation through a calcium-phospholipid pathway in an endothelial cell line.
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Affiliation(s)
- Doug Throckmorton
- Institute for Molecular Medicine and Genetics, Medical College of Georgia, Augusta, Georgia, USA
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41
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Signorelli P, Luberto C, Hannun YA. Ceramide inhibition of NF-kappaB activation involves reverse translocation of classical protein kinase C (PKC) isoenzymes: requirement for kinase activity and carboxyl-terminal phosphorylation of PKC for the ceramide response. FASEB J 2001; 15:2401-14. [PMID: 11689465 DOI: 10.1096/fj.01-0244com] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Protein kinase C (PKC) is known to activate NF-kappaB whereas the lipid mediator ceramide was recently shown to inhibit activation of this transcription factor (1, 2). In this study, the mechanisms by which ceramide interferes with this pathway were examined in Jurkat leukemia and MCF-7 breast cancer cells. Both exogenous and endogenous ceramide inhibited selectively PKC-mediated activation of NF-kappaB by reverting PKC translocation to the membrane. Next, confocal and immunofluorescence studies were performed to evaluate the direct effects of ceramide on PKC. These studies showed that ceramide inhibited translocation of a green fluorescent protein (GFP)-PKCbeta2 fusion protein in response to PMA. A mutant PKC in which autophosphorylation sites were mutated to alanine (PKC-DA) was resistant to ceramide. A kinase-inactive mutant (PKC-KR) was also resistant to ceramide action, and the results were supported using kinase inhibitors of the enzyme. Finally, overexpression of PKC-DA prevented, at least partly, the ability of ceramide to inhibit activation of NF-kappaB. Taken together, these studies show that ceramide has acute effects on translocation of PKC by inducing reverse translocation, and this reversal requires both the kinase activity of PKC and phosphorylation of the autophosphorylation sites.
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Affiliation(s)
- P Signorelli
- Department of Biochemistry and Molecular Biology; Medical University of South Carolina; Charleston, South Carolina 29425, USA
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42
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Tresini M, Lorenzini A, Frisoni L, Allen RG, Cristofalo VJ. Lack of Elk-1 phosphorylation and dysregulation of the extracellular regulated kinase signaling pathway in senescent human fibroblast. Exp Cell Res 2001; 269:287-300. [PMID: 11570821 DOI: 10.1006/excr.2001.5334] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Replicative senescence is characterized by numerous phenotypic alterations including the loss of proliferative capacity in response to mitogens and numerous changes in gene expression including impaired serum inducibility of the immediate-early genes c-fos and erg-1. Transcription of c-fos in response to mitogens depends on the activation of a multiprotein complex formed on the c-fos serum response element (SRE), which includes the transcription factors SRF (serum response factor) and TCF (ternary complex factor). Our data indicate that at least two defects are responsible for the decreased c-fos transcription in senescent cells, one caused by diminished DNA binding activity of the SRF and another resulting from impaired activation of the TCF, Elk-1. In nuclei isolated from serum stimulated senescent cells the activating phosphorylation of p62(TCF)/Elk-1, which is catalyzed by the members of the extracellular-regulated kinase (ERK) family was strikingly diminished and correlated with a decrease in the abundance of activated ERK proteins. In contrast, in total cell lysates ERK phosphorylation and ERK activity (normalized to total protein) reached similar levels following stimulation of early- and late-passage cells. Interestingly, senescent cells consistently exhibited higher ERK protein abundance. Thus, the proportion of phosphorylated (active) ERK molecules in stimulated senescent cells was lower than in early passage cells. The accumulation of unphosphorylated ERK molecules in senescent cells correlated with the diminished abundance of phosphorylated (active) MEK. These data indicate that in senescent cells there is a general dysregulation in the ERK signaling pathway, which results in the accumulation of inactive ERK molecules, decreased abundance of active ERK in the nucleus of senescent cells, and subsequent lack of activation of the transcription factor TCF(Elk-1). These impairments, together with the impaired DNA binding activity of SRF, could potentially account for the lack of c-fos expression in senescent cells and for multiple other molecular changes dependent upon this pathway.
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Affiliation(s)
- M Tresini
- The Lankenau Institute for Medical Research, 100 Lancaster Avenue, Wynnewood, Pennsylvania 19096, USA
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Abstract
T cell responses are altered in the aged in a manner usually interpreted as detrimental to host defences against infectious agents and possibly also against cancer. T cell dysregulation may be caused by any or a combination of stem cell deficits, compromised T cell differentiation, inefficient antigen processing and presentation by antigen presenting cells, suboptimal processing of the antigenic signal by T cells or inability of the T cell to respond appropriately thereafter. This review will focus on altered T cell signalling in ageing, encompassing not only alterations in signal transduction by the antigen-specific T cell receptor, but changes in the balance of positive and negative T cell costimulation and the resultant modified cytokine environment, the response to which is itself altered in ageing.
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Affiliation(s)
- G Pawelec
- Tübingen Ageing and Tumour Immunology Group, Second Department of Internal Medicine, University of Tübingen Medical School, Zentrum für Medizinsche Forschung, Waldhörnlestr. 22, D-72072, Tubingen, Germany.
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44
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Lee JS, Min DS, Park C, Park CS, Cho NJ. Phytosphingosine and C2-phytoceramide induce cell death and inhibit carbachol-stimulated phospholipase D activation in Chinese hamster ovary cells expressing the Caenorhabditis elegans muscarinic acetylcholine receptor. FEBS Lett 2001; 499:82-6. [PMID: 11418117 DOI: 10.1016/s0014-5793(01)02527-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Sphingolipid metabolites, such as sphingosine and ceramide, are known to play important roles in cell proliferation, differentiation and apoptosis, but the physiological roles of phytosphingosine (PHS) and phytoceramide (PHC) are poorly understood. In this study we investigated the effects of PHS, C2-PHC (N-acetylPHS) and C6-PHC (N-hexanoylPHS) on cell growth and intracellular signalling enzymes. Treatment of Chinese hamster ovary (CHO) cells with PHS, C2-PHC or C6-PHC resulted in cell death in a time- and dose-dependent manner. C2-PHC induced internucleosomal DNA fragmentation, whereas PHS or C6-PHC had little if any effect on DNA fragmentation under the same experimental conditions. Both PHS and C2-PHC inhibited carbachol-induced activation of phospholipase D (PLD), but not of phospholipase C (PLC), in CHO cells expressing the Caenorhabditis elegans muscarinic acetylcholine receptor (mAChR). On the other hand, no significant effect of C6-PHC on PLD or PLC was observed. Our results show that PHS and C2-PHC exert strong cytotoxic effects on CHO cells and modulate the mAChR-mediated signal transduction pathway.
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Affiliation(s)
- J S Lee
- School of Life Sciences, Chungbuk National University, Cheongju, South Korea
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45
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Hitomi T, Yanagi S, Inatome R, Ding J, Takano T, Yamamura H. Requirement of Syk-phospholipase C-gamma2 pathway for phorbol ester-induced phospholipase D activation in DT40 cells. Genes Cells 2001; 6:475-85. [PMID: 11380624 DOI: 10.1046/j.1365-2443.2001.00434.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Treatment of many cell types with phorbol esters stimulates phospholipase D (PLD) activity implying regulation of the enzyme by protein kinase C. Studies of the effects of several protein-tyrosine kinase (PTK) inhibitors have suggested that PTK(s) play some roles in the phorbol ester-induced PLD activation, but it remains unclear how and which PTK(s) is involved in this pathway. In this study, we investigated the roles of Syk and other PTKs for the phorbol esters, 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced PLD activation in K562 and DT40 cells. RESULTS TPA-induced PLD activation was remarkably reduced in both Syk dominant negative mutant K562 cells and Syk deficient DT40 B cells. Mutational analysis further indicated that two major autophosphorylation sites (Tyr-518 and Tyr-519) of Syk are critical for PLD activation. Similarly, TPA-induced PLD activation was reduced in Btk deficient cells, but unaffected in Lyn deficient cells. Finally, in cells deficient in the PLC-gamma2, one of the phosphorylated substrates regulated by Syk and Btk, TPA-induced PLD activation, as well as phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolysis was remarkably reduced. CONCLUSIONS We demonstrated that the Syk, Btk and PLC-gamma2 pathways are required for TPA-induced PLD activation in DT40 cells.
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Affiliation(s)
- T Hitomi
- Department of Biochemistry Kobe University School of Medicine, Chuo-ku, Kobe 650-0017, Japan
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Wheaton K, Sampsel K, Boisvert FM, Davy A, Robbins S, Riabowol K. Loss of functional caveolae during senescence of human fibroblasts. J Cell Physiol 2001; 187:226-35. [PMID: 11268002 DOI: 10.1002/jcp.1071] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Primary human fibroblasts have a finite replicative lifespan in culture that culminates in a unique state of growth arrest, termed senescence that is accompanied by distinct morphological and biochemical alterations. Senescent cell responses to extracellular stimuli are believed to be altered at a point after receptors are bound by ligand, leading to improper integration of the signals which initiate DNA replication. In this study we demonstrate that one of the key organizing membrane microdomains for receptor signaling, caveolae, are absent in senescent cells. A comparison of young and senescent cells indicated that senescent cells contained a higher total amount of caveolins 1 and 2 but had significantly less of both proteins in the caveolar fraction. Additionally, caveolar fractions from senescent cells completely lacked the tyrosine-kinase activity associated with functional caveolae. Furthermore, old cells had little caveolar protein exposed to the outer plasma membrane as estimated by using an in vivo biotinylation assay and no detectable caveolin 1 on the cell surface when processed for immunofluoresence and confocal microscopy. Together, these data suggest that a fundamental loss of signal integration at the plasma membrane of senescent cells is due to the loss of signaling competent caveolae.
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Affiliation(s)
- K Wheaton
- Department of Biochemistry and Molecular Biology, Southern Alberta Cancer Centre, University of Calgary, Heritage Medical Research Building, Calgary Alberta, Canada
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Freyberg Z, Sweeney D, Siddhanta A, Bourgoin S, Frohman M, Shields D. Intracellular localization of phospholipase D1 in mammalian cells. Mol Biol Cell 2001; 12:943-55. [PMID: 11294898 PMCID: PMC32278 DOI: 10.1091/mbc.12.4.943] [Citation(s) in RCA: 135] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Phospholipase D (PLD) hydrolyzes phosphatidylcholine to generate phosphatidic acid. In mammalian cells this reaction has been implicated in the recruitment of coatomer to Golgi membranes and release of nascent secretory vesicles from the trans-Golgi network. These observations suggest that PLD is associated with the Golgi complex; however, to date, because of its low abundance, the intracellular localization of PLD has been characterized only indirectly through overexpression of chimeric proteins. We have used highly sensitive antibodies to PLD1 together with immunofluorescence and immunogold electron microscopy as well as cell fractionation to identify the intracellular localization of endogenous PLD1 in several cell types. Although PLD1 had a diffuse staining pattern, it was enriched significantly in the Golgi apparatus and was also present in cell nuclei. On fragmentation of the Golgi apparatus by treatment with nocodazole, PLD1 closely associated with membrane fragments, whereas after inhibition of PA synthesis, PLD1 dissociated from the membranes. Overexpression of an hemagglutinin-tagged form of PLD1 resulted in displacement of the endogenous enzyme from its perinuclear localization to large vesicular structures. Surprisingly, when the Golgi apparatus collapsed in response to brefeldin A, the nuclear localization of PLD1 was enhanced significantly. Our data show that the intracellular localization of PLD1 is consistent with a role in vesicle trafficking from the Golgi apparatus and suggest that it also functions in the cell nucleus.
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Affiliation(s)
- Z Freyberg
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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Wang S, Banno Y, Nakashima S, Nozawa Y. Enzymatic characterization of phospholipase D of protozoan Tetrahymena cells. J Eukaryot Microbiol 2001; 48:194-201. [PMID: 12095108 DOI: 10.1111/j.1550-7408.2001.tb00303.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Phospholipase D (PLD), which is present in plant, bacterial, and mammalian cells, has been proposed to be involved in a number of cellular processes including transmembrane signaling and membrane deterioration. We demonstrated the existence of evolutionally related PLD activity in the unicellular eukaryotic protozoan Tetrahymena. The partial characterization of this enzyme showed that PLD in Tetrahymena cells was a neutral phospholipase, which catalyzed both transphosphatidylation and hydrolysis reac tions. The activity was markedly stimulated by phosphatidylinositol 4, 5-bisphosphate (PIP2) but was insensitive to phorbol 12-myristate 13-acetate (PMA) and guanosine 5'-3-O-(thio)triphosphate (GTPgammaS), suggesting that it is a PIP2-dependent PLD and that protein kinase C (PKC) and GTP-binding proteins are not implicated in the regulation of this enzyme. For its maximal activity Ca2+ was not required. This enzyme was also capable of hydrolyzing phosphatidylcholine (PC) but not phosphatidylethanolamine (PE), implying that PC was a preferred substrate. Subcellular fractionation showed that PLD-like activity localized mainly to the membrane fraction, especially microsomes. As an initial step to explore the functions of PLD in Tetrahymena, the PLD-like activity was determined during the different culture phases, and it was found to be significantly and transiently elevated in the early logarithmic phase, indicating its possible role in the development of Tetrahymena.
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Affiliation(s)
- S Wang
- Department of Biochemistry, Gifu University School of Medicine, Japan.
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Wright WE, Shay JW. Cellular senescence as a tumor-protection mechanism: the essential role of counting. Curr Opin Genet Dev 2001; 11:98-103. [PMID: 11163158 DOI: 10.1016/s0959-437x(00)00163-5] [Citation(s) in RCA: 218] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The term 'cellular senescence' has often been applied indiscriminately to any form of growth arrest of cultured cells that occurs either after some period in culture or following insults such as the overexpression of oncogenes. Recent reports have suggested there may be many mechanisms of cellular senescence. Our increasing understanding of the role of telomere shortening in the replicative aging of cultured fibroblasts now permits a re-examination of what may reasonably be called cellular senescence, and what most likely represents artifacts of the culture environment and/or specific cell-cycle control mechanisms.
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Affiliation(s)
- W E Wright
- Department of Cell Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9039, USA.
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