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Zoni V, Khaddaj R, Lukmantara I, Shinoda W, Yang H, Schneiter R, Vanni S. Seipin accumulates and traps diacylglycerols and triglycerides in its ring-like structure. Proc Natl Acad Sci U S A 2021; 118:e2017205118. [PMID: 33674387 PMCID: PMC7958289 DOI: 10.1073/pnas.2017205118] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Lipid droplets (LDs) are intracellular organelles responsible for lipid storage, and they emerge from the endoplasmic reticulum (ER) upon the accumulation of neutral lipids, mostly triglycerides (TG), between the two leaflets of the ER membrane. LD biogenesis takes place at ER sites that are marked by the protein seipin, which subsequently recruits additional proteins to catalyze LD formation. Deletion of seipin, however, does not abolish LD biogenesis, and its precise role in controlling LD assembly remains unclear. Here, we use molecular dynamics simulations to investigate the molecular mechanism through which seipin promotes LD formation. We find that seipin clusters TG, as well as its precursor diacylglycerol, inside its unconventional ring-like oligomeric structure and that both its luminal and transmembrane regions contribute to this process. This mechanism is abolished upon mutations of polar residues involved in protein-TG interactions into hydrophobic residues. Our results suggest that seipin remodels the membrane of specific ER sites to prime them for LD biogenesis.
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Affiliation(s)
- Valeria Zoni
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Rasha Khaddaj
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Ivan Lukmantara
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Wataru Shinoda
- Department of Materials Chemistry, Nagoya University, Chikusa-ku, 464-8603 Nagoya, Japan
| | - Hongyuan Yang
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Roger Schneiter
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Stefano Vanni
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland;
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Nutahara E, Abe E, Uno S, Ishibashi Y, Watanabe T, Hayashi M, Okino N, Ito M. The glycerol-3-phosphate acyltransferase PLAT2 functions in the generation of DHA-rich glycerolipids in Aurantiochytrium limacinum F26-b. PLoS One 2019; 14:e0211164. [PMID: 30699157 PMCID: PMC6353168 DOI: 10.1371/journal.pone.0211164] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 01/08/2019] [Indexed: 11/18/2022] Open
Abstract
Thraustochytrids possess docosahexaenoic acid (DHA, 22:6n-3) as acyl chain(s) of triacylglycerol (TG) and phosphatidylcholine (PC), some of which contain multiple DHAs. However, little is known about how these DHA-rich glycerolipids are produced in thraustochytrids. In this study, we identified PLAT2 in Aurantiochytrium limacinum F26-b as a glycerol-3-phosphate (G3P) acyltransferase (GPAT) by heterologous expression of the gene in budding yeast. Subsequently, we found that GPAT activity was reduced by disruption of the PLAT2 gene in A. limacinum, resulting in a decrease in DHA-containing lysophosphatidic acid (LPA 22:6). Conversely, overexpression of PLAT2 increased both GPAT activity and LPA 22:6. These results indicate that PLAT2 is a GPAT that transfers DHA to G3P in vivo as well as in vitro. Overexpression of the PLAT2 gene increased the production of a two DHA-containing diacylglycerol (DG 44:12), followed by an increase in the three DHA-containing TG (TG 66:18), two-DHA-containing TG (TG 60:12), and two DHA-containing PC (PC 44:12). However, overexpression of PLAT2 did not increase DHA-free DG (DG32:0), which was preferentially converted to three 16:0-containing TG (TG 48:0) but not two 16:0-containing PC (PC 32:0). Collectively, we revealed that DHA-rich glycerolipids are produced from a precursor, LPA 22:6, which is generated by incorporating DHA to G3P by PLAT2 in the A. limacinum.
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Affiliation(s)
- Eri Nutahara
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Moto-oka, Nishi-ku, Fukuoka, Japan
| | - Eriko Abe
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Moto-oka, Nishi-ku, Fukuoka, Japan
| | - Shinya Uno
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Moto-oka, Nishi-ku, Fukuoka, Japan
| | - Yohei Ishibashi
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Moto-oka, Nishi-ku, Fukuoka, Japan
| | - Takashi Watanabe
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Moto-oka, Nishi-ku, Fukuoka, Japan
| | - Masahiro Hayashi
- Department of Marine Biology and Environmental Sciences, Faculty of Agriculture, University of Miyazaki, 1–1 Gakuen-Kibanadai-Nishi, Miyazaki, Japan
| | - Nozomu Okino
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Moto-oka, Nishi-ku, Fukuoka, Japan
| | - Makoto Ito
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Moto-oka, Nishi-ku, Fukuoka, Japan
- Innovative Bio-architecture Center, Kyushu University, Moto-oka, Nishi-ku, Fukuoka, Japan
- * E-mail:
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Ma Q, Gabelli SB, Raben DM. Diacylglycerol kinases: Relationship to other lipid kinases. Adv Biol Regul 2019; 71:104-110. [PMID: 30348515 PMCID: PMC6347529 DOI: 10.1016/j.jbior.2018.09.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 09/24/2018] [Accepted: 09/25/2018] [Indexed: 04/17/2023]
Abstract
Lipid kinases regulate a wide variety of cellular functions and have emerged as one the most promising targets for drug design. Diacylglycerol kinases (DGKs) are a family of enzymes that catalyze the ATP-dependent phosphorylation of diacylglycerol (DAG) to phosphatidic acid (PtdOH). Despite the critical role in lipid biosynthesis, both DAG and PtdOH have been shown as bioactive lipids mediating a number of signaling pathways. Although there is increasing recognition of their role in signaling systems, our understanding of the key enzyme which regulate the balance of these two lipid messages remain limited. Solved structures provide a wealth of information for understanding the function and regulation of these enzymes. Solving the structures of mammalian DGKs by traditional NMR and X-ray crystallography approaches have been challenging and so far, there are still no three-dimensional structures of these DGKs. Despite this, some insights may be gained by examining the similarities and differences between prokaryotic DGKs and other mammalian lipid kinases. This review focuses on summarizing and comparing the structure of prokaryotic and mammalian DGKs as well as two other lipid kinases: sphingosine kinase and phosphatidylinositol-3-kinase. How these known lipid kinases structures relate to mammalian DGKs will also be discussed.
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Affiliation(s)
- Qianqian Ma
- The Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Sandra B Gabelli
- The Department of Biophysics, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Daniel M Raben
- The Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
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Tan WJ, Yang YC, Zhou Y, Huang LP, Xu L, Chen QF, Yu LJ, Xiao S. DIACYLGLYCEROL ACYLTRANSFERASE and DIACYLGLYCEROL KINASE Modulate Triacylglycerol and Phosphatidic Acid Production in the Plant Response to Freezing Stress. Plant Physiol 2018; 177:1303-1318. [PMID: 29853600 PMCID: PMC6053003 DOI: 10.1104/pp.18.00402] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 05/24/2018] [Indexed: 05/18/2023]
Abstract
Plants accumulate the lipids phosphatidic acid (PA), diacylglycerol (DAG), and triacylglycerol (TAG) during cold stress, but how plants balance the levels of these lipids to mediate cold responses remains unknown. The enzymes ACYL-COENZYME A:DIACYLGLYCEROL ACYLTRANSFERASE (DGAT) and DIACYLGLYCEROL KINASE (DGK) catalyze the conversion of DAG to TAG and PA, respectively. Here, we show that DGAT1, DGK2, DGK3, and DGK5 contribute to the response to cold in Arabidopsis (Arabidopsis thaliana). With or without cold acclimation, the dgat1 mutants exhibited higher sensitivity upon freezing exposure compared with the wild type. Under cold conditions, the dgat1 mutants showed reduced expression of C-REPEAT/DRE BINDING FACTOR2 and its regulons, which are essential for the acquisition of cold tolerance. Lipid profiling revealed that freezing significantly increased the levels of PA and DAG while decreasing TAG in the rosettes of dgat1 mutant plants. During freezing stress, the accumulation of PA in dgat1 plants stimulated NADPH oxidase activity and enhanced RbohD-dependent hydrogen peroxide production compared with the wild type. Moreover, the cold-inducible transcripts of DGK2, DGK3, and DGK5 were significantly more up-regulated in the dgat1 mutants than in the wild type during cold stress. Consistent with this observation, dgk2, dgk3, and dgk5 knockout mutants showed improved tolerance and attenuated PA production in response to freezing temperatures. Our findings demonstrate that the conversion of DAG to TAG by DGAT1 is critical for plant freezing tolerance, acting by balancing TAG and PA production in Arabidopsis.
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Affiliation(s)
- Wei-Juan Tan
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Yi-Cong Yang
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Ying Zhou
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Li-Ping Huang
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Le Xu
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Qin-Fang Chen
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Lu-Jun Yu
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Shi Xiao
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
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Sakane F, Mizuno S, Takahashi D, Sakai H. Where do substrates of diacylglycerol kinases come from? Diacylglycerol kinases utilize diacylglycerol species supplied from phosphatidylinositol turnover-independent pathways. Adv Biol Regul 2018; 67:101-108. [PMID: 28918129 DOI: 10.1016/j.jbior.2017.09.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 09/08/2017] [Accepted: 09/08/2017] [Indexed: 06/07/2023]
Abstract
Diacylglycerol kinase (DGK) phosphorylates diacylglycerol (DG) to produce phosphatidic acid (PA). Mammalian DGK comprises ten isozymes (α-κ) and regulates a wide variety of physiological and pathological events, such as cancer, type II diabetes, neuronal disorders and immune responses. DG and PA consist of various molecular species that have different acyl chains at the sn-1 and sn-2 positions, and consequently, mammalian cells contain at least 50 structurally distinct DG/PA species. Because DGK is one of the components of phosphatidylinositol (PI) turnover, the generally accepted dogma is that all DGK isozymes utilize 18:0/20:4-DG derived from PI turnover. We recently established a specific liquid chromatography-mass spectrometry method to analyze which PA species were generated by DGK isozymes in a cell stimulation-dependent manner. Interestingly, we determined that DGKδ, which is closely related to the pathogenesis of type II diabetes, preferentially utilized 14:0/16:0-, 14:0/16:1-, 16:0/16:0-, 16:0/16:1-, 16:0/18:0- and 16:0/18:1-DG species (X:Y = the total number of carbon atoms: the total number of double bonds) supplied from the phosphatidylcholine-specific phospholipase C pathway, but not 18:0/20:4-DG, in high glucose-stimulated C2C12 myoblasts. Moreover, DGKα mainly consumed 14:0/16:0-, 16:0/18:1-, 18:0/18:1- and 18:1/18:1-DG species during cell proliferation in AKI melanoma cells. Furthermore, we found that 16:0/16:0-PA was specifically produced by DGKζ in Neuro-2a cells during retinoic acid- and serum starvation-induced neuronal differentiation. These results indicate that DGK isozymes utilize a variety of DG molecular species derived from PI turnover-independent pathways as substrates in different stimuli and cells. DGK isozymes phosphorylate various DG species to generate various PA species. It was revealed that the modes of activation of conventional and novel protein kinase isoforms by DG molecular species varied considerably. However, PA species-selective binding proteins have not been found to date. Therefore, we next attempted to identify PA species-selective binding proteins from the mouse brain and identified α-synuclein, which has causal links to Parkinson's disease. Intriguingly, we determined that among phospholipids, including several PA species (16:0/16:0-PA, 16:0/18:1-PA, 18:1/18:1-PA, 18:0/18:0-PA and 18:0/20:4-PA); 18:1/18:1-PA was the most strongly bound PA to α-synuclein. Moreover, 18:1/18:1-PA strongly enhanced secondary structural changes from the random coil form to the α-helix form and generated a multimeric and proteinase K-resistant α-synuclein protein. In contrast with the dogma described above, our recent studies strongly suggest that PI turnover-derived DG species and also various DG species derived from PI turnover-independent pathways are utilized by DGK isozymes. DG species supplied from distinct pathways may be utilized by DGK isozymes based on different stimuli present in different types of cells, and individual PA molecular species would have specific targets and exert their own physiological functions.
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Affiliation(s)
- Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan.
| | - Satoru Mizuno
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Daisuke Takahashi
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Hiromichi Sakai
- Department of Biosignaling and Radioisotope Experiment, Interdisciplinary Center for Science Research, Organization for Research and Academic Information, Shimane University, Izumo, Japan
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Qiu Y, Sui X, Zhan Y, Xu C, Li X, Ning Y, Zhi X, Yin L. Steroidogenic acute regulatory protein (StAR) overexpression attenuates HFD-induced hepatic steatosis and insulin resistance. Biochim Biophys Acta Mol Basis Dis 2017; 1863:978-990. [PMID: 28153708 DOI: 10.1016/j.bbadis.2017.01.026] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 12/18/2016] [Accepted: 01/28/2017] [Indexed: 12/11/2022]
Abstract
Non-alcoholic fatty liver disease (NAFLD) covers a wide spectrum of liver pathology. Intracellular lipid accumulation is the first step in the development and progression of NAFLD. Steroidogenic acute regulatory protein (StAR) plays an important role in the synthesis of bile acid and intracellular lipid homeostasis and cholesterol metabolism. We hypothesize that StAR is involved in non-alcoholic fatty liver disease (NAFLD) pathogenesis. The hypothesis was identified using free fatty acid (FFA)-overloaded NAFLD in vitro model and high-fat diet (HFD)-induced NAFLD mouse model transfected by recombinant adenovirus encoding StAR (StAR). StAR expression was also examined in pathology samples of patients with fatty liver by immunohistochemical staining. We found that the expression level of StAR was reduced in the livers obtained from fatty liver patients and NAFLD mice. Additionally, StAR overexpression decreased the levels of hepatic lipids and maintained the hepatic glucose homeostasis due to the activation of farnesoid x receptor (FXR). StAR overexpression attenuated the impairment of insulin signaling in fatty liver. This protective role of StAR was owing to a reduction of intracellular diacylglycerol levels and the phosphorylation of PKCε. Furthermore, FXR inactivation reversed the observed beneficial effects of StAR. The present study revealed that StAR overexpression can reduce hepatic lipid accumulation, regulate glucose metabolism and attenuate insulin resistance through a mechanism involving the activation of FXR. Our study suggests that StAR may be a potential therapeutic target for NAFLD.
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Affiliation(s)
- Yanyan Qiu
- Department of Physiology & Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Xianxian Sui
- Department of Physiology & Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Yongkun Zhan
- Department of Physiology & Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Chen Xu
- Department of Pathology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Xiaobo Li
- Department of Physiology & Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Yanxia Ning
- Department of Physiology & Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Xiuling Zhi
- Department of Physiology & Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China; Laboratory of Medical Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai, China.
| | - Lianhua Yin
- Department of Physiology & Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China.
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7
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Lan D, Wang Q, Xu J, Zhou P, Yang B, Wang Y. Residue Asn277 affects the stability and substrate specificity of the SMG1 lipase from Malassezia globosa. Int J Mol Sci 2015; 16:7273-88. [PMID: 25837472 PMCID: PMC4425016 DOI: 10.3390/ijms16047273] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 03/20/2015] [Accepted: 03/20/2015] [Indexed: 11/25/2022] Open
Abstract
Thermostability and substrate specificity are important characteristics of enzymes for industrial application, which can be improved by protein engineering. SMG1 lipase from Malassezia globosa is a mono- and diacylglycerol lipase (MDL) that shows activity toward mono- and diacylglycerols, but no activity toward triacylglycerols. SMG1 lipase is considered a potential biocatalyst applied in oil/fat modification and its crystal structure revealed that an interesting residue-Asn277 may contribute to stabilize loop 273–278 and the 3104 helix which are important to enzyme characterization. In this study, to explore its role in affecting the stability and catalytic activity, mutagenesis of N277 with Asp (D), Val (V), Leu (L) and Phe (F) was conducted. Circular dichroism (CD) spectral analysis and half-life measurement showed that the N277D mutant has better thermostability. The melting temperature and half-life of the N277D mutant were 56.6 °C and 187 min, respectively, while that was 54.6 °C and 121 min for SMG1 wild type (WT). Biochemical characterization of SMG1 mutants were carried out to test whether catalytic properties were affected by mutagenesis. N277D had similar enzymatic properties as SMG1 WT, but N277F showed a different substrate selectivity profile as compared to other SMG1 mutants. Analysis of the SMG1 3D model suggested that N277D formed a salt bridge via its negative charged carboxyl group with a positively charged guanidino group of R227, which might contribute to confer N277D higher temperature stability. These findings not only provide some clues to understand the molecular basis of the lipase structure/function relationship but also lay the framework for engineering suitable MDL lipases for industrial applications.
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Affiliation(s)
- Dongming Lan
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510006, China.
| | - Qian Wang
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510006, China.
| | - Jinxin Xu
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China.
| | - Pengfei Zhou
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510006, China.
| | - Bo Yang
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510006, China.
| | - Yonghua Wang
- College of Light Industry and Food Sciences, South China University of Technology, Guangzhou 510640, China.
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Dixon JL, Kim YK, Brinker A, Quadro L. Loss of β-carotene 15,15'-oxygenase in developing mouse tissues alters esterification of retinol, cholesterol and diacylglycerols. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1841:34-43. [PMID: 23988655 DOI: 10.1016/j.bbalip.2013.08.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 08/11/2013] [Accepted: 08/13/2013] [Indexed: 11/20/2022]
Abstract
We provide novel insights into the function(s) of β-carotene-15,15'-oxygenase (CMOI) during embryogenesis. By performing in vivo and in vitro experiments, we showed that CMOI influences not only lecithin:retinol acyltransferase but also acyl CoA:retinol acyltransferase reaction in the developing tissues at mid-gestation. In addition, LC/MS lipidomics analysis of the CMOI-/- embryos showed reduced levels of four phosphatidylcholine and three phosphatidylethanolamine acyl chain species, and of eight triacylglycerol species with four or more unsaturations and fifty-two or more carbons in the acyl chains. Cholesteryl esters of arachidonate, palmitate, linoleate, and DHA were also reduced to less than 30% of control. Analysis of the fatty acyl CoA species ruled out a loss in fatty acyl CoA synthetase capability. Comparison of acyl species suggested significantly decreased 18:2, 18:3, 20:1, 20:4, or 22:6 acyl chains within the above lipids in CMOI-null embryos. Furthermore, LCAT, ACAT1 and DGAT2 mRNA levels were also downregulated in CMOI-/- embryos. These data strongly support the notion that, in addition to cleaving β-carotene to generate retinoids, CMOI serves an additional function(s) in retinoid and lipid metabolism and point to its role in the formation of specific lipids, possibly for use in nervous system tissue.
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Affiliation(s)
- Joseph L Dixon
- Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ 08901, USA; Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901, USA
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9
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Strijbis K, Tafesse FG, Fairn GD, Witte MD, Dougan SK, Watson N, Spooner E, Esteban A, Vyas VK, Fink GR, Grinstein S, Ploegh HL. Bruton's Tyrosine Kinase (BTK) and Vav1 contribute to Dectin1-dependent phagocytosis of Candida albicans in macrophages. PLoS Pathog 2013; 9:e1003446. [PMID: 23825946 PMCID: PMC3694848 DOI: 10.1371/journal.ppat.1003446] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2013] [Accepted: 05/07/2013] [Indexed: 12/28/2022] Open
Abstract
Phagocytosis of the opportunistic fungal pathogen Candida albicans by cells of the innate immune system is vital to prevent infection. Dectin-1 is the major phagocytic receptor involved in anti-fungal immunity. We identify two new interacting proteins of Dectin-1 in macrophages, Bruton's Tyrosine Kinase (BTK) and Vav1. BTK and Vav1 are recruited to phagocytic cups containing C. albicans yeasts or hyphae but are absent from mature phagosomes. BTK and Vav1 localize to cuff regions surrounding the hyphae, while Dectin-1 lines the full length of the phagosome. BTK and Vav1 colocalize with the lipid PI(3,4,5)P3 and F-actin at the phagocytic cup, but not with diacylglycerol (DAG) which marks more mature phagosomal membranes. Using a selective BTK inhibitor, we show that BTK contributes to DAG synthesis at the phagocytic cup and the subsequent recruitment of PKCε. BTK- or Vav1-deficient peritoneal macrophages display a defect in both zymosan and C. albicans phagocytosis. Bone marrow-derived macrophages that lack BTK or Vav1 show reduced uptake of C. albicans, comparable to Dectin1-deficient cells. BTK- or Vav1-deficient mice are more susceptible to systemic C. albicans infection than wild type mice. This work identifies an important role for BTK and Vav1 in immune responses against C. albicans.
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Affiliation(s)
- Karin Strijbis
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
| | - Fikadu G. Tafesse
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
| | - Gregory D. Fairn
- Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Department of Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Martin D. Witte
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
| | - Stephanie K. Dougan
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
| | - Nicki Watson
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
| | - Eric Spooner
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
| | - Alexandre Esteban
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
| | - Valmik K. Vyas
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
| | - Gerald R. Fink
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
| | - Sergio Grinstein
- Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Department of Surgery, University of Toronto, Toronto, Ontario, Canada
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Hidde L. Ploegh
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
- * E-mail:
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Lev S, Katz B, Tzarfaty V, Minke B. Signal-dependent hydrolysis of phosphatidylinositol 4,5-bisphosphate without activation of phospholipase C: implications on gating of Drosophila TRPL (transient receptor potential-like) channel. J Biol Chem 2012; 287:1436-47. [PMID: 22065576 PMCID: PMC3256851 DOI: 10.1074/jbc.m111.266585] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 10/23/2011] [Indexed: 11/06/2022] Open
Abstract
In Drosophila, a phospholipase C (PLC)-mediated signaling cascade, couples photo-excitation of rhodopsin to the opening of the transient receptor potential (TRP) and TRP-like (TRPL) channels. A lipid product of PLC, diacylglycerol (DAG), and its metabolites, polyunsaturated fatty acids (PUFAs) may function as second messengers of channel activation. However, how can one separate between the increase in putative second messengers, change in pH, and phosphatidylinositol 4,5-bisphosphate (PI(4,5)P(2)) depletion when exploring the TRPL gating mechanism? To answer this question we co-expressed the TRPL channels together with the muscarinic (M1) receptor, enabling the openings of TRPL channels via G-protein activation of PLC. To dissect PLC activation of TRPL into its molecular components, we used a powerful method that reduced plasma membrane-associated PI(4,5)P(2) in HEK cells within seconds without activating PLC. Upon the addition of a dimerizing drug, PI(4,5)P(2) was selectively hydrolyzed in the cell membrane without producing DAG, inositol trisphosphate, or calcium signals. We show that PI(4,5)P(2) is not an inhibitor of TRPL channel activation. PI(4,5)P(2) hydrolysis combined with either acidification or application of DAG analogs failed to activate the channels, whereas PUFA did activate the channels. Moreover, a reduction in PI(4,5)P(2) levels or inhibition of DAG lipase during PLC activity suppressed the PLC-activated TRPL current. This suggests that PI(4,5)P(2) is a crucial substrate for PLC-mediated activation of the channels, whereas PUFA may function as the channel activator. Together, this study defines a narrow range of possible mechanisms for TRPL gating.
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Affiliation(s)
- Shaya Lev
- From the Department of Medical Neurobiology and the Kühne Minerva Center for Studies of Visual Transduction, Institute of Medical Research Israel-Canada, The Edmond and Lily Safra Center for Brain Sciences, Faculty of Medicine of the Hebrew University, Jerusalem 91120, Israel
| | - Ben Katz
- From the Department of Medical Neurobiology and the Kühne Minerva Center for Studies of Visual Transduction, Institute of Medical Research Israel-Canada, The Edmond and Lily Safra Center for Brain Sciences, Faculty of Medicine of the Hebrew University, Jerusalem 91120, Israel
| | - Vered Tzarfaty
- From the Department of Medical Neurobiology and the Kühne Minerva Center for Studies of Visual Transduction, Institute of Medical Research Israel-Canada, The Edmond and Lily Safra Center for Brain Sciences, Faculty of Medicine of the Hebrew University, Jerusalem 91120, Israel
| | - Baruch Minke
- From the Department of Medical Neurobiology and the Kühne Minerva Center for Studies of Visual Transduction, Institute of Medical Research Israel-Canada, The Edmond and Lily Safra Center for Brain Sciences, Faculty of Medicine of the Hebrew University, Jerusalem 91120, Israel
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11
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Rani SH, Krishna THA, Saha S, Negi AS, Rajasekharan R. Defective in cuticular ridges (DCR) of Arabidopsis thaliana, a gene associated with surface cutin formation, encodes a soluble diacylglycerol acyltransferase. J Biol Chem 2010; 285:38337-47. [PMID: 20921218 PMCID: PMC2992267 DOI: 10.1074/jbc.m110.133116] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 10/01/2010] [Indexed: 11/06/2022] Open
Abstract
A key step in the triacylglycerol (TAG) biosynthetic pathway is the final acylation of diacylglycerol (DAG) by DAG acyltransferase. In silico analysis has revealed that the DCR (defective in cuticular ridges) (At5g23940) gene has a typical HX(4)D acyltransferase motif at the N-terminal end and a lipid binding motif VX(2)GF at the middle of the sequence. To understand the biochemical function, the gene was overexpressed in Escherichia coli, and the purified recombinant protein was found to acylate DAG specifically in an acyl-CoA-dependent manner. Overexpression of At5g23940 in a Saccharomyces cerevisiae quadruple mutant deficient in DAG acyltransferases resulted in TAG accumulation. At5g23940 rescued the growth of this quadruple mutant in the oleate-containing medium, whereas empty vector control did not. Lipid particles were localized in the cytosol of At5g23940-transformed quadruple mutant cells, as observed by oil red O staining. There was an incorporation of 16-hydroxyhexadecanoic acid into TAG in At5g23940-transformed cells of quadruple mutant. Here we report a soluble acyl-CoA-dependent DAG acyltransferase from Arabidopsis thaliana. Taken together, these data suggest that a broad specific DAG acyltransferase may be involved in the cutin as well as in the TAG biosynthesis by supplying hydroxy fatty acid.
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Affiliation(s)
- Sapa Hima Rani
- From the Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India and
| | - T. H. Anantha Krishna
- From the Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India and
| | - Saikat Saha
- From the Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India and
| | - Arvind Singh Negi
- the Central Institute of Medicinal and Aromatic Plants, Council of Scientific and Industrial Research, Lucknow 220015, India
| | - Ram Rajasekharan
- the Central Institute of Medicinal and Aromatic Plants, Council of Scientific and Industrial Research, Lucknow 220015, India
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12
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Fritz M, Lokstein H, Hackenberg D, Welti R, Roth M, Zähringer U, Fulda M, Hellmeyer W, Ott C, Wolter FP, Heinz E. Channeling of eukaryotic diacylglycerol into the biosynthesis of plastidial phosphatidylglycerol. J Biol Chem 2007; 282:4613-4625. [PMID: 17158889 DOI: 10.1074/jbc.m606295200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Plastidial glycolipids contain diacylglycerol (DAG) moieties, which are either synthesized in the plastids (prokaryotic lipids) or originate in the extraplastidial compartment (eukaryotic lipids) necessitating their transfer into plastids. In contrast, the only phospholipid in plastids, phosphatidylglycerol (PG), contains exclusively prokaryotic DAG backbones. PG contributes in several ways to the functions of chloroplasts, but it is not known to what extent its prokaryotic nature is required to fulfill these tasks. As a first step toward answering this question, we produced transgenic tobacco plants that contain eukaryotic PG in thylakoids. This was achieved by targeting a bacterial DAG kinase into chloroplasts in which the heterologous enzyme was also incorporated into the envelope fraction. From lipid analysis we conclude that the DAG kinase phosphorylated eukaryotic DAG forming phosphatidic acid, which was converted into PG. This resulted in PG with 2-3 times more eukaryotic than prokaryotic DAG backbones. In the newly formed PG the unique Delta3-trans-double bond, normally confined to 3-trans-hexadecenoic acid, was also found in sn-2-bound cis-unsaturated C18 fatty acids. In addition, a lipidomics technique allowed the characterization of phosphatidic acid, which is assumed to be derived from eukaryotic DAG precursors in the chloroplasts of the transgenic plants. The differences in lipid composition had only minor effects on measured functions of the photosynthetic apparatus, whereas the most obvious phenotype was a significant reduction in growth.
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Affiliation(s)
- Markus Fritz
- Biozentrum Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, D-22609 Hamburg, Germany; Max-Planck-Gesellschaft, Generalverwaltung, Hofgartenstrasse 8, D-80539 München, Germany
| | - Heiko Lokstein
- Institut für Biochemie und Biologie, Universität Potsdam, Pflanzenphysiologie, Karl-Liebknecht-Strasse 24-25, D-14476 Golm, Germany
| | - Dieter Hackenberg
- Institut für Biologie/Pflanzenphysiologie, Humboldt-Universität zu Berlin, Unter den Linden 6, D-10099 Berlin
| | - Ruth Welti
- Division of Biology, Kansas State University, Kansas Lipidomics Research Center, Manhattan, Kansas 66506-4901
| | - Mary Roth
- Division of Biology, Kansas State University, Kansas Lipidomics Research Center, Manhattan, Kansas 66506-4901
| | - Ulrich Zähringer
- Leibniz-Zentrum für Medizin und Biowissenschaften, Forschungszentrum Borstel, Parkallee 4, D-23845 Borstel, Germany
| | - Martin Fulda
- Biozentrum Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, D-22609 Hamburg, Germany; Albrecht-von-Haller-Institut für Pflanzenwissenschaften, Georg-August Universität Göttingen, Biochemie der Pflanze, Justus-von-Liebig-Weg 11, D-37077 Göttingen, Germany, and the.
| | - Wiebke Hellmeyer
- Biozentrum Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, D-22609 Hamburg, Germany
| | - Claudia Ott
- Biozentrum Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, D-22609 Hamburg, Germany
| | - Frank P Wolter
- Biozentrum Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, D-22609 Hamburg, Germany; Bundesverband Deutscher Pflanzenzüchter, GVSmbH, Kaufmannstrasse 71-73, D-53115 Bonn, Germany
| | - Ernst Heinz
- Biozentrum Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, D-22609 Hamburg, Germany
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Gronert K, Kantarci A, Levy BD, Clish CB, Odparlik S, Hasturk H, Badwey JA, Colgan SP, Van Dyke TE, Serhan CN. A molecular defect in intracellular lipid signaling in human neutrophils in localized aggressive periodontal tissue damage. J Immunol 2004; 172:1856-61. [PMID: 14734770 PMCID: PMC4318492 DOI: 10.4049/jimmunol.172.3.1856] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Host defense mechanisms are impaired in patients with congenital neutrophil (polymorphonuclear neutrophils (PMN)) defects. Impaired PMN chemotaxis is observed in localized aggressive periodontitis (LAP), a familial disorder characterized by destruction of the supporting structures of dentition. In the present studies, we sought evidence for molecular events underlying this aberrant human PMN phenotype. To this end, PMN transendothelial migration and superoxide anion generation were assessed with LAP patients and asymptomatic family members, as well as patients with other chronic mucosal inflammation. PMN from LAP patients showed decreased transmigration across vascular endothelial monolayers (18 +/- 12% of control, n = 4) and increased superoxide anion generation (358 +/- 37%, p = 0.003). Gene expression was analyzed using oligonucleotide microarrays and fluorescence-based kinetic PCR. cDNA microarray and kinetic-PCR analysis revealed diminished RNA expression of leukocyte-type diacylglycerol (DAG) kinase alpha in PMN from LAP patients (4.6 +/- 1.7 relative units, n = 6, p = 0.007) compared with asymptomatic individuals (51 +/- 27 relative units, n = 7). DAG kinase activity was monitored by DAG phosphorylation and individual DAG molecular species were quantified using liquid chromatography and tandem mass spectrometry-based lipidomics. DAG kinase activity was also significantly decreased (73 +/- 2%, p = 0.007) and correlated with increased accumulation of 1,2-diacyl-sn-3-glycerol substrates (p = 0.01). These results implicate defects in both PMN transendothelial migration and PMN DAG kinase alpha signaling as disordered functions in LAP. Moreover, they identify a potential molecular lesion in PMN signal transduction that may account for their aberrant responses and tissue destruction in this disease.
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Affiliation(s)
- Karsten Gronert
- Department of Anesthesiology, Perioperative and Pain Medicine, Center for Experimental Therapeutics and Reperfusion Injury, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02115
| | - Alpdogan Kantarci
- Department of Periodontology and Oral Biology, Boston University Goldman School of Dental Medicine, Boston, MA 02118
| | - Bruce D. Levy
- Department of Anesthesiology, Perioperative and Pain Medicine, Center for Experimental Therapeutics and Reperfusion Injury, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02115
| | - Clary B. Clish
- Department of Anesthesiology, Perioperative and Pain Medicine, Center for Experimental Therapeutics and Reperfusion Injury, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02115
| | - Sabine Odparlik
- Department of Anesthesiology, Perioperative and Pain Medicine, Center for Experimental Therapeutics and Reperfusion Injury, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02115
| | - Hatice Hasturk
- Department of Periodontology and Oral Biology, Boston University Goldman School of Dental Medicine, Boston, MA 02118
| | - John A. Badwey
- Department of Anesthesiology, Perioperative and Pain Medicine, Center for Experimental Therapeutics and Reperfusion Injury, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02115
| | - Sean P. Colgan
- Department of Anesthesiology, Perioperative and Pain Medicine, Center for Experimental Therapeutics and Reperfusion Injury, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02115
| | - Thomas E. Van Dyke
- Department of Periodontology and Oral Biology, Boston University Goldman School of Dental Medicine, Boston, MA 02118
| | - Charles N. Serhan
- Department of Anesthesiology, Perioperative and Pain Medicine, Center for Experimental Therapeutics and Reperfusion Injury, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02115
- Address correspondence and reprint requests to: Prof. Charles N. Serhan, Center for Experimental Therapeutics and Reperfusion Injury, Thorn 7, Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 02115.
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14
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Okusawa T, Fujita M, Nakamura JI, Into T, Yasuda M, Yoshimura A, Hara Y, Hasebe A, Golenbock DT, Morita M, Kuroki Y, Ogawa T, Shibata KI. Relationship between structures and biological activities of mycoplasmal diacylated lipopeptides and their recognition by toll-like receptors 2 and 6. Infect Immun 2004; 72:1657-65. [PMID: 14977973 PMCID: PMC355991 DOI: 10.1128/iai.72.3.1657-1665.2004] [Citation(s) in RCA: 145] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The lipopeptide FSL-1 [S-(2,3-bispalmitoyloxypropyl)-Cys-Gly-Asp-Pro-Lys-His-Pro-Lys-Ser-Phe, Pam(2)CGDPKHPKSF] synthesized on the basis of the N-terminal structure of a Mycoplasma salivarium lipoprotein capable of activating normal human gingival fibroblasts to induce the cell surface expression of ICAM-1 revealed an activity to induce production of monocyte chemoattractant protein 1, interleukin-6 (IL-6), and IL-8. FSL-1 also activated macrophages to produce tumor necrosis factor alpha as the Mycoplasma fermentans-derived lipopeptide MALP-2 (Pam(2)CGNNDESNISFKEK), a potent macrophage-activating lipopeptide, did. The level of the activity of FSL-1 was higher than that of MALP-2. This result suggests that the difference in the amino acid sequence of the peptide portion affects the activity because the framework structure other than the amino acid sequence of the former is the same as that of the latter. To determine minimal structural requirements for the activity of FSL-1, the diacylglyceryl Cys and the peptide portions were examined for this activity. Both portions did not reveal the activity. A single amino acid substitution from Phe to Arg and a fatty acid substitution from palmitic acid to stearic acid drastically reduced the activity. Similar results were obtained in measuring the NF-kappaB reporter activity of FSL-1 to human embryonic kidney 293 cells transfected with Toll-like receptor 2 and 6, together with a NF-kappaB-dependent luciferase reporter plasmid. These results suggest that both the diacylglyceryl and the peptide portions of FSL-1 are indispensable for the expression of biological activities and for the recognition by Toll-like receptors 2 and 6 and that the recognition of FSL-1 by Toll-like receptors 2 and 6 appears to be hydrophobic.
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Affiliation(s)
- Tsugumi Okusawa
- Department of Oral Pathobiological Science, Hokkaido University Graduate School of Dental Medicine, Nishi 7, Kita 13, Kita-kuSapporo 060-8586, Japan
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15
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Itoh YH, Kurosawa N, Uda I, Sugai A, Tanoue S, Itoh T, Horiuchi T, Itoh T. Metallosphaera sedula TA-2, a calditoglycerocaldarchaeol deletion strain of a thermoacidophilic archaeon. Extremophiles 2001; 5:241-5. [PMID: 11523893 DOI: 10.1007/s007920100195] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A spherical thermoacidophilic archaeon, strain TA-2, was obtained from acidic hot springs located in Ohwaku Valley, Hakone, Japan. This isolate is an obligate aerobic chemoorganoheterotroph that grows optimally at about 75 degrees C, pH 2.8. The G + C content of DNA from TA-2 is 47 mol%. The 16S rRNA gene from TA-2 showed more than 99% similarity with those of Metallosphaera sedula and Metallosphaera prunae and less than 92% similarity with other members of the order Sulfolobales. DNA-DNA hybridization experiments showed more than 93% genomic DNA homology among TA-2, M. sedula DSM5348T, and M. prunae DSM10039T. However, TA-2 lacks calditoglycerocaldarchaeol derivatives, which are usually found in the membrane lipids of members of the order Sulfolobales. Therefore, calditoglycerocaldarchaeol may not be essential for survival in thermophilic and acidophilic environments. The isolate was deposited as Metallosphaera sedula TA-2 (JCM 9064, IFO 15160).
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Affiliation(s)
- Y H Itoh
- Department of Bioengineering, Faculty of Engineering, Soka University, Hachioji, Tokyo, Japan.
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16
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Ganapathy P, Shanmugam G. Dimethyl sulphoxide alters mitogen induced production of diacylglycerol and GTP-binding to plasma membranes in mouse embryo fibroblasts. Biochem Mol Biol Int 1995; 35:739-48. [PMID: 7627124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Dimethyl sulphoxide (DMSO) is a polar solvent often used as an inducer of erythroid differentiation. In order to elucidate the mode of action of DMSO, we studied its effects on two early events in signal transduction, namely diacylglycerol (DAG) production and guanosine triphosphate (GTP) binding. Mouse embryo fibroblasts showed a bimodal profile of diacylglycerol synthesis in the presence of DMSO. Platelet derived growth factor (PDGF) mediated synthesis of diacylglycerol synthesis was inhibited by DMSO. Also DMSO down regulated serum induced GTP-binding to isolated plasma membranes of mouse embryo fibroblasts. However, the control and the ras (T24) oncogene transformed Rat-2 cells did not show any increase in GTP-binding on serum stimulation while showing a marginal decrease in GTP-binding in the presence of DMSO. DMSO may hence act by inhibiting the perpetuation of mitogenic signal transduction at an early stage.
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Affiliation(s)
- P Ganapathy
- Cancer Biology Division, School of Biological Sciences, Madurai Kamaraj University, India
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Abstract
Genes involved in the transduction of signals required for normal cell proliferation commonly appear to be subverted in the neoplastic process. One such group is the highly conserved family of ras genes, which have been detected as transforming genes in a wide variety of naturally occurring tumours. By analogy with other known G proteins, the p21 proteins encoded by ras genes may act as regulatory proteins in the transduction of signals that lead to DNA synthesis. A major pathway involved in the DNA synthesis induced by growth factors is mediated by phosphatidylinositol turnover: cleavage of phosphoinositides by phospholipase C produces 1,2-diacylglycerol, and inositol phosphates. The former acts as an essential cofactor for protein kinase C (ref. 4), and inositol-(1,4,5)-triphosphate mobilizes Ca2+ from non-mitochondrial intracellular stores. We demonstrate a reproducible increase in 1,2-diacylglycerol, in the absence of a detectable increase in inositol phosphates, in transformed cells containing Ha-ras oncogenes and with different membrane targeting signals for the ras p21 protein. These findings suggest that a source other than phosphoinositides exists for the generation of 1,2-diacylglycerol and that the Ha-ras oncogene specifically activates this novel pathway for 1,2-diacylglycerol production.
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Affiliation(s)
- J C Lacal
- Laboratory of Cellular and Molecular Biology, National Cancer Institute, Bethesda, Maryland 20892
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