151
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Hassaninasab A, Han GS, Carman GM. Tips on the analysis of phosphatidic acid by the fluorometric coupled enzyme assay. Anal Biochem 2017; 526:69-70. [PMID: 28359787 DOI: 10.1016/j.ab.2017.03.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 03/23/2017] [Accepted: 03/25/2017] [Indexed: 02/05/2023]
Abstract
The fluorometric coupled enzyme assay to measure phosphatidic acid (PA) involves the solubilization of extracted lipids in Triton X-100, deacylation, and the oxidation of PA-derived glycerol-3-phosphate to produce hydrogen peroxide for conversion of Amplex Red to resorufin. The enzyme assay is sensitive, but plagued by high background fluorescence from the peroxide-containing detergent and incomplete heat inactivation of lipoprotein lipase. These problems affecting the assay reproducibility were obviated by the use of highly pure Triton X-100 and by sufficient heat inactivation of the lipase enzyme. The enzyme assay could accurately measure the PA content from the subcellular fractions of yeast cells.
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Affiliation(s)
- Azam Hassaninasab
- Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, NJ 08901, United States
| | - Gil-Soo Han
- Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, NJ 08901, United States
| | - George M Carman
- Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, NJ 08901, United States.
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152
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An endoplasmic reticulum-engineered yeast platform for overproduction of triterpenoids. Metab Eng 2017; 40:165-175. [DOI: 10.1016/j.ymben.2017.02.007] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 01/13/2017] [Accepted: 02/14/2017] [Indexed: 11/23/2022]
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153
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Dey P, Su WM, Han GS, Carman GM. Phosphorylation of lipid metabolic enzymes by yeast protein kinase C requires phosphatidylserine and diacylglycerol. J Lipid Res 2017; 58:742-751. [PMID: 28154205 DOI: 10.1194/jlr.m075036] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 02/01/2017] [Indexed: 12/29/2022] Open
Abstract
Protein kinase C in Saccharomyces cerevisiae, i.e., Pkc1, is an enzyme that plays an important role in signal transduction and the regulation of lipid metabolic enzymes. Pkc1 is structurally similar to its counterparts in higher eukaryotes, but its requirement of phosphatidylserine (PS) and diacylglycerol (DAG) for catalytic activity has been unclear. In this work, we examined the role of these lipids in Pkc1 activity with protein and peptide substrates. In agreement with previous findings, yeast Pkc1 did not require PS and DAG for its activity on the peptide substrates derived from lipid metabolic proteins such as Pah1 [phosphatidate (PA) phosphatase], Nem1 (PA phosphatase phosphatase), and Spo7 (protein phosphatase regulatory subunit). However, the lipids were required for Pkc1 activity on the protein substrates Pah1, Nem1, and Spo7. Compared with DAG, PS had a greater effect on Pkc1 activity, and its dose-dependent interaction with the protein kinase was shown by the liposome binding assay. The Pkc1-mediated degradation of Pah1 was attenuated in the cho1Δ mutant, which is deficient in PS synthase, supporting the notion that the phospholipid regulates Pkc1 activity in vivo.
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Affiliation(s)
- Prabuddha Dey
- Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, NJ 08901
| | - Wen-Min Su
- Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, NJ 08901
| | - Gil-Soo Han
- Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, NJ 08901
| | - George M Carman
- Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, NJ 08901.
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154
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Shimizu K, Fukushima H, Ogura K, Lien EC, Nihira NT, Zhang J, North BJ, Guo A, Nagashima K, Nakagawa T, Hoshikawa S, Watahiki A, Okabe K, Yamada A, Toker A, Asara JM, Fukumoto S, Nakayama KI, Nakayama K, Inuzuka H, Wei W. The SCFβ-TRCP E3 ubiquitin ligase complex targets Lipin1 for ubiquitination and degradation to promote hepatic lipogenesis. Sci Signal 2017; 10:10/460/eaah4117. [PMID: 28049764 DOI: 10.1126/scisignal.aah4117] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The SCFβ-TRCP E3 ubiquitin ligase complex plays pivotal roles in normal cellular physiology and in pathophysiological conditions. Identification of β-transducin repeat-containing protein (β-TRCP) substrates is therefore critical to understand SCFβ-TRCP biology and function. We used a β-TRCP-phosphodegron motif-specific antibody in a β-TRCP substrate screen coupled with tandem mass spectrometry and identified multiple β-TRCP substrates. One of these substrates was Lipin1, an enzyme and suppressor of the family of sterol regulatory element-binding protein (SREBP) transcription factors, which activate genes encoding lipogenic factors. We showed that SCFβ-TRCP specifically interacted with and promoted the polyubiquitination of Lipin1 in a manner that required phosphorylation of Lipin1 by mechanistic target of rapamycin 1 (mTORC1) and casein kinase I (CKI). β-TRCP depletion in HepG2 hepatocellular carcinoma cells resulted in increased Lipin1 protein abundance, suppression of SREBP-dependent gene expression, and attenuation of triglyceride synthesis. Moreover, β-TRCP1 knockout mice showed increased Lipin1 protein abundance and were protected from hepatic steatosis induced by a high-fat diet. Together, these data reveal a critical physiological function of β-TRCP in regulating hepatic lipid metabolic homeostasis in part through modulating Lipin1 stability.
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Affiliation(s)
- Kouhei Shimizu
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.,Center for Advanced Stem Cell and Regenerative Research, Tohoku University Graduate School of Dentistry, Sendai 980-8575, Japan
| | - Hidefumi Fukushima
- Center for Advanced Stem Cell and Regenerative Research, Tohoku University Graduate School of Dentistry, Sendai 980-8575, Japan
| | - Kohei Ogura
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.,Department of Infectious Diseases, National Center for Global Health and Medicine, Tokyo 162-8655, Japan
| | - Evan C Lien
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Naoe Taira Nihira
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Jinfang Zhang
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Brian J North
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Ailan Guo
- Cell Signaling Technology Inc., Danvers, MA 01923, USA
| | - Katsuyuki Nagashima
- Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka 814-0193, Japan
| | - Tadashi Nakagawa
- Division of Cell Proliferation, United Centers for Advanced Research and Translational Medicine, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
| | - Seira Hoshikawa
- Center for Advanced Stem Cell and Regenerative Research, Tohoku University Graduate School of Dentistry, Sendai 980-8575, Japan.,Division of Pediatric Dentistry, Department of Oral Health and Development Sciences, Tohoku University Graduate School of Dentistry, Sendai 980-8575, Japan
| | - Asami Watahiki
- Center for Advanced Stem Cell and Regenerative Research, Tohoku University Graduate School of Dentistry, Sendai 980-8575, Japan
| | - Koji Okabe
- Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka 814-0193, Japan
| | - Aya Yamada
- Division of Pediatric Dentistry, Department of Oral Health and Development Sciences, Tohoku University Graduate School of Dentistry, Sendai 980-8575, Japan
| | - Alex Toker
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - John M Asara
- Division of Signal Transduction, Beth Israel Deaconess Medical Center and Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Satoshi Fukumoto
- Center for Advanced Stem Cell and Regenerative Research, Tohoku University Graduate School of Dentistry, Sendai 980-8575, Japan.,Division of Pediatric Dentistry, Department of Oral Health and Development Sciences, Tohoku University Graduate School of Dentistry, Sendai 980-8575, Japan
| | - Keiichi I Nakayama
- Division of Cell Regulation Systems, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
| | - Keiko Nakayama
- Division of Cell Proliferation, United Centers for Advanced Research and Translational Medicine, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
| | - Hiroyuki Inuzuka
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA. .,Center for Advanced Stem Cell and Regenerative Research, Tohoku University Graduate School of Dentistry, Sendai 980-8575, Japan
| | - Wenyi Wei
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
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155
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Lordén G, Sanjuán-García I, de Pablo N, Meana C, Alvarez-Miguel I, Pérez-García MT, Pelegrín P, Balsinde J, Balboa MA. Lipin-2 regulates NLRP3 inflammasome by affecting P2X7 receptor activation. J Exp Med 2016; 214:511-528. [PMID: 28031477 PMCID: PMC5294860 DOI: 10.1084/jem.20161452] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 10/23/2016] [Accepted: 12/12/2016] [Indexed: 01/31/2023] Open
Abstract
Lordén et al. show that the phosphatidic acid phosphatase lipin-2 is a key regulator of the cellular machinery that generates IL-1β in macrophages. This work provides a molecular explanation for the development of the autoinflammatory disease known as Majeed syndrome. Mutations in human LPIN2 produce a disease known as Majeed syndrome, the clinical manifestations of which are ameliorated by strategies that block IL-1β or its receptor. However the role of lipin-2 during IL-1β production remains elusive. We show here that lipin-2 controls excessive IL-1β formation in primary human and mouse macrophages by several mechanisms, including activation of the inflammasome NLRP3. Lipin-2 regulates MAPK activation, which mediates synthesis of pro–IL-1β during inflammasome priming. Lipin-2 also inhibits the activation and sensitization of the purinergic receptor P2X7 and K+ efflux, apoptosis-associated speck-like protein with a CARD domain oligomerization, and caspase-1 processing, key events during inflammasome activation. Reduced levels of lipin-2 in macrophages lead to a decrease in cellular cholesterol levels. In fact, restoration of cholesterol concentrations in cells lacking lipin-2 decreases ion currents through the P2X7 receptor, and downstream events that drive IL-1β production. Furthermore, lipin-2–deficient mice exhibit increased sensitivity to high lipopolysaccharide doses. Collectively, our results unveil lipin-2 as a critical player in the negative regulation of NLRP3 inflammasome.
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Affiliation(s)
- Gema Lordén
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, 47003 Valladolid, Spain.,Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, 28029 Madrid, Spain
| | - Itziar Sanjuán-García
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, 47003 Valladolid, Spain.,Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, 28029 Madrid, Spain
| | - Nagore de Pablo
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, 47003 Valladolid, Spain.,Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, 28029 Madrid, Spain
| | - Clara Meana
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, 47003 Valladolid, Spain.,Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, 28029 Madrid, Spain
| | - Inés Alvarez-Miguel
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, 47003 Valladolid, Spain.,Departamento de Fisiología, Facultad de Medicina, Universidad de Valladolid, 47003 Valladolid, Spain
| | - M Teresa Pérez-García
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, 47003 Valladolid, Spain.,Departamento de Fisiología, Facultad de Medicina, Universidad de Valladolid, 47003 Valladolid, Spain
| | - Pablo Pelegrín
- Molecular Inflammation Group, Murcia Biomedical Research Institute, Hospital Virgen de la Arrixaca, Carretera Buenavista, 30120 Murcia, Spain
| | - Jesús Balsinde
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, 47003 Valladolid, Spain.,Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, 28029 Madrid, Spain
| | - María A Balboa
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, 47003 Valladolid, Spain .,Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, 28029 Madrid, Spain
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156
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Hardman D, McFalls D, Fakas S. Characterization of phosphatidic acid phosphatase activity in the oleaginous yeastYarrowia lipolyticaand its role in lipid biosynthesis. Yeast 2016; 34:83-91. [DOI: 10.1002/yea.3216] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 10/11/2016] [Accepted: 10/12/2016] [Indexed: 01/05/2023] Open
Affiliation(s)
- Derell Hardman
- Department of Food and Animal Sciences; Alabama A&M University; Normal, AL 35762 USA
| | - Daniel McFalls
- Department of Food and Animal Sciences; Alabama A&M University; Normal, AL 35762 USA
| | - Stylianos Fakas
- Department of Food and Animal Sciences; Alabama A&M University; Normal, AL 35762 USA
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157
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Kim JY, Kim G, Lim SC, Choi HS. LPIN1 promotes epithelial cell transformation and mammary tumourigenesis via enhancing insulin receptor substrate 1 stability. Carcinogenesis 2016; 37:1199-1209. [PMID: 27729374 DOI: 10.1093/carcin/bgw104] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 08/25/2016] [Accepted: 10/10/2016] [Indexed: 02/07/2023] Open
Abstract
LPIN1 is a protein that exhibits dual functions as a phosphatidic acid phosphatase enzyme in regulation of triglyceride and glycerophospholipid metabolism and a transcriptional coregulator. Through unknown tumour-promoting mechanism, LPIN1 frequently observed in various human cancer cell lines controls main cellular processes involved in cancer progression. Here, we demonstrate that LPIN1 enhances the tumour-promoting function of insulin receptor substrate 1 (IRS1) by controlling IRS1 stability. LPIN1 interacts with IRS1 in an insulin growth factor-1-dependent signalling pathway and inhibits its serine phosphorylation, and thereby eliminating ubiquitin-dependent degradation of IRS1 via proteasomal and lysosomal pathways. Consequently, LPIN1 overexpression increases IRS1 abundance and enhances IRS1's ability to induce epithelial cell proliferation and mammary tumourigenesis. By contrast, depletion or inhibition of LPIN1 in breast cancer cells leads to a decreased IRS1 level, which subsequently inhibits the RAF1-mediated signalling pathway and AP-1 activity. In the syngeneic 4T1 breast cancer model, LPIN1 overexpression increased tumour development, whereas inhibition of LPIN1 and IRS1 suppressed it. Consistent with these observations, LPIN1 levels were positively correlated with IRS1 expression in human breast cancer. Thus, our results indicate a mechanism by which IRS1 expression is increased in breast cancer, and LPIN1 may be a promising drug target for anticancer therapy.
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Affiliation(s)
| | | | - Sung-Chul Lim
- Department of Pathology, School of Medicine, Chosun University, 309 Philmundaero, Dong-gu, Gwangju 61452, Republic of Korea
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158
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Qiu Y, Hassaninasab A, Han GS, Carman GM. Phosphorylation of Dgk1 Diacylglycerol Kinase by Casein Kinase II Regulates Phosphatidic Acid Production in Saccharomyces cerevisiae. J Biol Chem 2016; 291:26455-26467. [PMID: 27834677 DOI: 10.1074/jbc.m116.763839] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 11/08/2016] [Indexed: 11/06/2022] Open
Abstract
In the yeast Saccharomyces cerevisiae, Dgk1 diacylglycerol (DAG) kinase catalyzes the CTP-dependent phosphorylation of DAG to form phosphatidic acid (PA). The enzyme in conjunction with Pah1 PA phosphatase controls the levels of PA and DAG for the synthesis of triacylglycerol and membrane phospholipids, the growth of the nuclear/endoplasmic reticulum membrane, and the formation of lipid droplets. Little is known about how DAG kinase activity is regulated by posttranslational modification. In this work, we examined the phosphorylation of Dgk1 DAG kinase by casein kinase II (CKII). When phosphate groups were globally reduced using nonspecific alkaline phosphatase, Triton X-100-solubilized membranes from DGK1-overexpressing cells showed a 7.7-fold reduction in DAG kinase activity; the reduced enzyme activity could be increased 5.5-fold by treatment with CKII. Dgk1(1-77) expressed heterologously in Escherichia coli was phosphorylated by CKII on a serine residue, and its phosphorylation was dependent on time as well as on the concentrations of CKII, ATP, and Dgk1(1-77). We used site-specific mutagenesis, coupled with phosphorylation analysis and phosphopeptide mapping, to identify Ser-45 and Ser-46 of Dgk1 as the CKII target sites, with Ser-46 being the major phosphorylation site. In vivo, the S46A and S45A/S46A mutations of Dgk1 abolished the stationary phase-dependent stimulation of DAG kinase activity. In addition, the phosphorylation-deficient mutations decreased Dgk1 function in PA production and in eliciting pah1Δ phenotypes, such as the expansion of the nuclear/endoplasmic reticulum membrane, reduced lipid droplet formation, and temperature sensitivity. This work demonstrates that the CKII-mediated phosphorylation of Dgk1 regulates its function in the production of PA.
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Affiliation(s)
- Yixuan Qiu
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Azam Hassaninasab
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Gil-Soo Han
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - George M Carman
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
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159
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Temprano A, Sembongi H, Han GS, Sebastián D, Capellades J, Moreno C, Guardiola J, Wabitsch M, Richart C, Yanes O, Zorzano A, Carman GM, Siniossoglou S, Miranda M. Redundant roles of the phosphatidate phosphatase family in triacylglycerol synthesis in human adipocytes. Diabetologia 2016; 59:1985-94. [PMID: 27344312 PMCID: PMC4969345 DOI: 10.1007/s00125-016-4018-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 05/23/2016] [Indexed: 12/20/2022]
Abstract
AIMS/HYPOTHESIS In mammals, the evolutionary conserved family of Mg(2+)-dependent phosphatidate phosphatases (PAP1), involved in phospholipid and triacylglycerol synthesis, consists of lipin-1, lipin-2 and lipin-3. While mutations in the murine Lpin1 gene cause lipodystrophy and its knockdown in mouse 3T3-L1 cells impairs adipogenesis, deleterious mutations of human LPIN1 do not affect adipose tissue distribution. However, reduced LPIN1 and PAP1 activity has been described in participants with type 2 diabetes. We aimed to characterise the roles of all lipin family members in human adipose tissue and adipogenesis. METHODS The expression of the lipin family was analysed in adipose tissue in a cross-sectional study. Moreover, the effects of lipin small interfering RNA (siRNA)-mediated depletion on in vitro human adipogenesis were assessed. RESULTS Adipose tissue gene expression of the lipin family is altered in type 2 diabetes. Depletion of every lipin family member in a human Simpson-Golabi-Behmel syndrome (SGBS) pre-adipocyte cell line, alters expression levels of adipogenic transcription factors and lipid biosynthesis genes in early stages of differentiation. Lipin-1 knockdown alone causes a 95% depletion of PAP1 activity. Despite the reduced PAP1 activity and alterations in early adipogenesis, lipin-silenced cells differentiate and accumulate neutral lipids. Even combinatorial knockdown of lipins shows mild effects on triacylglycerol accumulation in mature adipocytes. CONCLUSIONS/INTERPRETATION Overall, our data support the hypothesis of alternative pathways for triacylglycerol synthesis in human adipocytes under conditions of repressed lipin expression. We propose that induction of alternative lipid phosphate phosphatases, along with the inhibition of lipid hydrolysis, contributes to the maintenance of triacylglycerol content to near normal levels.
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Affiliation(s)
- Ana Temprano
- Joan XXIII University Hospital, Pere Virgili Health Research Institut (IISPV), Modular Building, C/ Mallafre Guasch, Tarragona, 43005, Spain
- Department of Biochemistry and Molecular Biology, Rovira i Virgili University, Tarragona, Spain
| | - Hiroshi Sembongi
- Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/Medical Research Council Building, Hills Road, Cambridge, CB2 0XY, UK
- , Chesterford Research Park, Little Chesterford, Saffron Walden, UK
| | - Gil-Soo Han
- Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, NJ, USA
| | - David Sebastián
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain
- Biomedical Research Networking Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
| | - Jordi Capellades
- Biomedical Research Networking Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
- Centre for Omic Sciences, Rovira i Virgili University, Reus, Spain
| | - Cristóbal Moreno
- Joan XXIII University Hospital, Pere Virgili Health Research Institut (IISPV), Modular Building, C/ Mallafre Guasch, Tarragona, 43005, Spain
- Biomedical Research Networking Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
| | - Juan Guardiola
- Department of Pulmonary, Critical Care and Sleep Medicine, University of Louisville, Louisville, KY, USA
| | - Martin Wabitsch
- Division of Paediatric Endocrinology and Diabetes, Interdisciplinary Obesity Clinic, University Clinic for Child and Adolescent Medicine, University of Ulm, Ulm, Germany
| | - Cristóbal Richart
- Joan XXIII University Hospital, Pere Virgili Health Research Institut (IISPV), Modular Building, C/ Mallafre Guasch, Tarragona, 43005, Spain
- GEMMAIR Research Group - Applied Medicine, Department of Medicine and Surgery, Rovira i Virgili University (URV), Tarragona, Spain
| | - Oscar Yanes
- Biomedical Research Networking Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
- Centre for Omic Sciences, Rovira i Virgili University, Reus, Spain
- Department of Electronic Engineering, Rovira i Virgili University, Tarragona, Spain
| | - Antonio Zorzano
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain
- Biomedical Research Networking Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
| | - George M Carman
- Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, NJ, USA
| | - Symeon Siniossoglou
- Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/Medical Research Council Building, Hills Road, Cambridge, CB2 0XY, UK.
| | - Merce Miranda
- Joan XXIII University Hospital, Pere Virgili Health Research Institut (IISPV), Modular Building, C/ Mallafre Guasch, Tarragona, 43005, Spain.
- Biomedical Research Networking Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain, .
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160
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Fernández-Murray JP, McMaster CR. Lipid synthesis and membrane contact sites: a crossroads for cellular physiology. J Lipid Res 2016; 57:1789-1805. [PMID: 27521373 DOI: 10.1194/jlr.r070920] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Indexed: 12/17/2022] Open
Abstract
Membrane contact sites (MCSs) are regions of close apposition between different organelles that contribute to the functional integration of compartmentalized cellular processes. In recent years, we have gained insight into the molecular architecture of several contact sites, as well as into the regulatory mechanisms that underlie their roles in cell physiology. We provide an overview of two selected topics where lipid metabolism intersects with MCSs and organelle dynamics. First, the role of phosphatidic acid phosphatase, Pah1, the yeast homolog of metazoan lipin, toward the synthesis of triacylglycerol is outlined in connection with the seipin complex, Fld1/Ldb16, and lipid droplet formation. Second, we recapitulate the different contact sites connecting mitochondria and the endomembrane system and emphasize their contribution to phospholipid synthesis and their coordinated regulation. A comprehensive view is emerging where the multiplicity of contact sites connecting different cellular compartments together with lipid transfer proteins functioning at more than one MCS allow for functional redundancy and cross-regulation.
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161
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Grillet M, Dominguez Gonzalez B, Sicart A, Pöttler M, Cascalho A, Billion K, Hernandez Diaz S, Swerts J, Naismith TV, Gounko NV, Verstreken P, Hanson PI, Goodchild RE. Torsins Are Essential Regulators of Cellular Lipid Metabolism. Dev Cell 2016; 38:235-47. [PMID: 27453503 DOI: 10.1016/j.devcel.2016.06.017] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 05/18/2016] [Accepted: 06/12/2016] [Indexed: 01/10/2023]
Abstract
Torsins are developmentally essential AAA+ proteins, and mutation of human torsinA causes the neurological disease DYT1 dystonia. They localize in the ER membranes, but their cellular function remains unclear. We now show that dTorsin is required in Drosophila adipose tissue, where it suppresses triglyceride levels, promotes cell growth, and elevates membrane lipid content. We also see that human torsinA at the inner nuclear membrane is associated with membrane expansion and elevated cellular lipid content. Furthermore, the key lipid metabolizing enzyme, lipin, is mislocalized in dTorsin-KO cells, and dTorsin increases levels of the lipin substrate, phosphatidate, and reduces the product, diacylglycerol. Finally, genetic suppression of dLipin rescues dTorsin-KO defects, including adipose cell size, animal growth, and survival. These findings identify that torsins are essential regulators of cellular lipid metabolism and implicate disturbed lipid biology in childhood-onset DYT1 dystonia.
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Affiliation(s)
- Micheline Grillet
- VIB Centre for the Biology of Disease, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium; Department of Human Genetics, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium
| | - Beatriz Dominguez Gonzalez
- VIB Centre for the Biology of Disease, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium; Department of Human Genetics, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium
| | - Adria Sicart
- VIB Centre for the Biology of Disease, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium; Department of Human Genetics, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium
| | - Maria Pöttler
- VIB Centre for the Biology of Disease, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium; Department of Human Genetics, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium
| | - Ana Cascalho
- VIB Centre for the Biology of Disease, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium; Department of Human Genetics, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium
| | - Karolien Billion
- VIB Centre for the Biology of Disease, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium; Department of Human Genetics, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium
| | - Sergio Hernandez Diaz
- VIB Centre for the Biology of Disease, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium; Department of Human Genetics, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium
| | - Jef Swerts
- VIB Centre for the Biology of Disease, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium; Department of Human Genetics, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium
| | - Teresa V Naismith
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Natalia V Gounko
- VIB Centre for the Biology of Disease, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium; Department of Human Genetics, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium; Electron Microscopy Platform, VIB Bio-Imaging Core, Campus Gasthuisberg, 3000 Leuven, Belgium
| | - Patrik Verstreken
- VIB Centre for the Biology of Disease, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium; Department of Human Genetics, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium
| | - Phyllis I Hanson
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Rose E Goodchild
- VIB Centre for the Biology of Disease, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium; Department of Human Genetics, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium.
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162
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Fakas S. Lipid biosynthesis in yeasts: A comparison of the lipid biosynthetic pathway between the model nonoleaginous yeast Saccharomyces cerevisiae and the model oleaginous yeast Yarrowia lipolytica. Eng Life Sci 2016; 17:292-302. [PMID: 32624775 DOI: 10.1002/elsc.201600040] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 05/20/2016] [Accepted: 06/09/2016] [Indexed: 01/08/2023] Open
Abstract
Lipid biosynthesis and its regulation have been studied mostly in the nonoleaginous yeast Saccharomyces cerevisiae that serves as a model for eukaryotic cells. On the other hand, the yeast Yarrowia lipolytica has been put forward as a model for oleaginous microorganisms because its genetics is known and tools for its genetic manipulation are becoming increasingly available. A comparison of the lipid biosynthetic pathways that function in these two microorganisms shows many similarities in key biosynthetic and regulatory steps. An example is the enzyme phosphatidic acid phosphatase that controls the synthesis of triacylglycerol (TAG) in both yeasts. Controlling the TAG synthesis is crucial for metabolic engineering efforts that aim to increase the production of microbial lipids (i.e. single cell oils) because TAG comprises the final product of these processes. At the same time the comparison reveals fundamental differences (e.g. in the generation of acetyl-CoA for lipid biosynthesis) stemming from the oleaginous nature of Y. lipolytica. These differences warranty more studies in Y. lipolytica where the biochemistry and molecular biology of oleaginicity can be further explored.
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Affiliation(s)
- Stylianos Fakas
- Department of Food and Animal Sciences Alabama A&M University Normal AL USA
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163
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Miner GE, Starr ML, Hurst LR, Sparks RP, Padolina M, Fratti RA. The Central Polybasic Region of the Soluble SNARE (Soluble N-Ethylmaleimide-sensitive Factor Attachment Protein Receptor) Vam7 Affects Binding to Phosphatidylinositol 3-Phosphate by the PX (Phox Homology) Domain. J Biol Chem 2016; 291:17651-63. [PMID: 27365394 DOI: 10.1074/jbc.m116.725366] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Indexed: 12/14/2022] Open
Abstract
The yeast vacuole requires four SNAREs to trigger membrane fusion including the soluble Qc-SNARE Vam7. The N-terminal PX domain of Vam7 binds to the lipid phosphatidylinositol 3-phosphate (PI3P) and the tethering complex HOPS (homotypic fusion and vacuole protein sorting complex), whereas the C-terminal SNARE motif forms SNARE complexes. Vam7 also contains an uncharacterized middle domain that is predicted to be a coiled-coil domain with multiple helices. One helix contains a polybasic region (PBR) composed of Arg-164, Arg-168, Lys-172, Lys-175, Arg-179, and Lys-186. Polybasic regions are often associated with nonspecific binding to acidic phospholipids including phosphoinositides. Although the PX (phox homology) domain alone binds PI3P, we theorized that the Vam7 PBR could bind to additional acidic phospholipids enriched at fusion sites. Mutating each of the basic residues in the PBR to an alanine (Vam7-6A) led to attenuated vacuole fusion. The defective fusion of Vam7-6A was due in part to inefficient association with its cognate SNAREs and HOPS, yet the overall vacuole association of Vam7-6A was similar to wild type. Experiments testing the binding of Vam7 to specific signaling lipids showed that mutating the PBR to alanines augmented binding to PI3P. The increased binding to PI3P by Vam7-6A likely contributed to the observed wild type levels of vacuole association, whereas protein-protein interactions were diminished. PI3P binding was inhibited when the PX domain mutant Y42A was introduced into Vam7-6A to make Vam7-7A. Thus the Vam7 PBR affects PI3P binding by the PX domain and in turn affects binding to SNAREs and HOPS to support efficient fusion.
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Affiliation(s)
- Gregory E Miner
- From the Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Matthew L Starr
- From the Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Logan R Hurst
- From the Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Robert P Sparks
- From the Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Mark Padolina
- From the Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Rutilio A Fratti
- From the Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
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164
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Barbosa AD, Siniossoglou S. Spatial distribution of lipid droplets during starvation: Implications for lipophagy. Commun Integr Biol 2016; 9:e1183854. [PMID: 27574533 PMCID: PMC4988446 DOI: 10.1080/19420889.2016.1183854] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 04/22/2016] [Accepted: 04/22/2016] [Indexed: 11/09/2022] Open
Abstract
Survival during starvation depends largely on metabolic energy, which is stored in the form of neutral lipids in specialized organelles known as lipid droplets. The precursors for the synthesis of neutral lipids are also used for membrane biogenesis, which is required for cell growth and proliferation. Therefore cells must possess mechanisms to preferentially channel lipid precursors toward either membrane synthesis or lipid droplet storage, in response to nutrient status. How this partitioning is spatially regulated within the endoplasmic reticulum (ER) where lipid droplets co-localize, remains poorly understood. We have recently shown that at the onset of starvation lipid droplets concentrate at a perinuclear ER subdomain flanking the nucleus-vacuole junction (NVJ) and that this is crucial for maintaining proper nuclear shape and ER membrane organization. Here we show that disruption of the NVJ does not block the translocation and internalization of lipid droplets into the vacuole for their degradation, which takes place at later stages of starvation. We propose that alternative pathways of lipid droplet translocation from the ER to the vacuole may exist to enable stationary phase-induced lipophagy.
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Affiliation(s)
| | - Symeon Siniossoglou
- Cambridge Institute for Medical Research, University of Cambridge , Cambridge, UK
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165
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Yang PL, Hsu TH, Wang CW, Chen RH. Lipid droplets maintain lipid homeostasis during anaphase for efficient cell separation in budding yeast. Mol Biol Cell 2016; 27:2368-80. [PMID: 27307588 PMCID: PMC4966979 DOI: 10.1091/mbc.e16-02-0106] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 06/08/2016] [Indexed: 11/11/2022] Open
Abstract
The neutral lipids steryl ester and triacylglycerol (TAG) are stored in the membrane-bound organelle lipid droplet (LD) in essentially all eukaryotic cells. It is unclear what physiological conditions require the mobilization or storage of these lipids. Here, we study the budding yeast mutant are1Δ are2Δ dga1Δ lro1Δ, which cannot synthesize the neutral lipids and therefore lacks LDs. This quadruple mutant is delayed at cell separation upon release from mitotic arrest. The cells have abnormal septa, unstable septin assembly during cytokinesis, and prolonged exocytosis at the division site at the end of cytokinesis. Lipidomic analysis shows a marked increase of diacylglycerol (DAG) and phosphatidic acid, the precursors for TAG, in the mutant during mitotic exit. The cytokinesis and separation defects are rescued by adding phospholipid precursors or inhibiting fatty acid synthesis, which both reduce DAG levels. Our results suggest that converting excess lipids to neutral lipids for storage during mitotic exit is important for proper execution of cytokinesis and efficient cell separation.
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Affiliation(s)
- Po-Lin Yang
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Tzu-Han Hsu
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Chao-Wen Wang
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Rey-Huei Chen
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
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166
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Kelly AA, Feussner I. Oil is on the agenda: Lipid turnover in higher plants. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:1253-1268. [PMID: 27155216 DOI: 10.1016/j.bbalip.2016.04.021] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 04/23/2016] [Accepted: 04/25/2016] [Indexed: 12/13/2022]
Abstract
Lipases hydrolyze ester bonds within lipids. This process is called lipolysis. They are key players in lipid turnover and involved in numerous metabolic pathways, many of which are shared between organisms like the mobilization of neutral or storage lipids or lipase-mediated membrane lipid homeostasis. Some reactions though are predominantly present in certain organisms, such as the production of signaling molecules (endocannabinoids) by diacylglycerol (DAG) and monoacylglycerol (MAG) lipases in mammals and plants or the jasmonate production in flowering plants. This review aims at giving an overview of the different functional classes of lipases and respective well-known activities, with a focus on the most recent findings in plant biology for selected classes. Here we will put an emphasis on the physiological role and contribution of lipases to the turnover of neutral lipids found in seed oil and other vegetative tissue as candidates for increasing the economical values of crop plants. This article is part of a Special Issue entitled: Plant Lipid Biology edited by Kent D. Chapman and Ivo Feussner.
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Affiliation(s)
- Amélie A Kelly
- Georg-August-University, Albrecht-von-Haller-Institute for Plant Sciences, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
| | - Ivo Feussner
- Georg-August-University, Albrecht-von-Haller-Institute for Plant Sciences, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany; Georg-August-University, Göttingen Center for Molecular Biosciences (GZMB), Justus-von-Liebig Weg 11, 37077 Göttingen, Germany; Georg-August-University, International Center for Advanced Studies of Energy Conversion (ICASEC), Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
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167
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Xu C, Shanklin J. Triacylglycerol Metabolism, Function, and Accumulation in Plant Vegetative Tissues. ANNUAL REVIEW OF PLANT BIOLOGY 2016; 67:179-206. [PMID: 26845499 DOI: 10.1146/annurev-arplant-043015-111641] [Citation(s) in RCA: 149] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Oils in the form of triacylglycerols are the most abundant energy-dense storage compounds in eukaryotes, and their metabolism plays a key role in cellular energy balance, lipid homeostasis, growth, and maintenance. Plants accumulate oils primarily in seeds and fruits. Plant oils are used for food and feed and, increasingly, as feedstocks for biodiesel and industrial chemicals. Although plant vegetative tissues do not accumulate significant levels of triacylglycerols, they possess a high capacity for their synthesis, storage, and metabolism. The development of plants that accumulate oil in vegetative tissues presents an opportunity for expanded production of triacylglycerols as a renewable and sustainable bioenergy source. Here, we review recent progress in the understanding of triacylglycerol synthesis, turnover, storage, and function in leaves and discuss emerging genetic engineering strategies targeted at enhancing triacylglycerol accumulation in biomass crops. Such plants could potentially be modified to produce oleochemical feedstocks or nutraceuticals.
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Affiliation(s)
- Changcheng Xu
- Biology Department, Brookhaven National Laboratory, Upton, New York 11973; ,
| | - John Shanklin
- Biology Department, Brookhaven National Laboratory, Upton, New York 11973; ,
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168
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Meseroll RA, Cohen-Fix O. The Malleable Nature of the Budding Yeast Nuclear Envelope: Flares, Fusion, and Fenestrations. J Cell Physiol 2016; 231:2353-60. [PMID: 26909870 DOI: 10.1002/jcp.25355] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 02/19/2016] [Indexed: 11/10/2022]
Abstract
In eukaryotes, the nuclear envelope (NE) physically separates nuclear components and activities from rest of the cell. The NE also provides rigidity to the nucleus and contributes to chromosome organization. At the same time, the NE is highly dynamic; it must change shape and rearrange its components during development and throughout the cell cycle, and its morphology can be altered in response to mutation and disease. Here we focus on the NE of budding yeast, Saccharomyces cerevisiae, which has several unique features: it remains intact throughout the cell cycle, expands symmetrically during interphase, elongates during mitosis and, expands asymmetrically during mitotic delay. Moreover, its NE is safely breached during mating and when large structures, such as nuclear pore complexes and the spindle pole body, are embedded into its double membrane. The budding yeast NE lacks lamins and yet the nucleus is capable of maintaining a spherical shape throughout interphase. Despite these eccentricities, studies of the budding yeast NE have uncovered interesting, and likely conserved, processes that contribute to NE dynamics. In particular, we discuss the processes that drive and enable NE expansion and the dramatic changes in the NE that lead to extensions and fenestrations. J. Cell. Physiol. 231: 2353-2360, 2016. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.
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Affiliation(s)
- Rebecca A Meseroll
- The Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Orna Cohen-Fix
- The Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
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169
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Hsieh LS, Su WM, Han GS, Carman GM. Phosphorylation of Yeast Pah1 Phosphatidate Phosphatase by Casein Kinase II Regulates Its Function in Lipid Metabolism. J Biol Chem 2016; 291:9974-90. [PMID: 27044741 DOI: 10.1074/jbc.m116.726588] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Indexed: 12/14/2022] Open
Abstract
Pah1 phosphatidate phosphatase in Saccharomyces cerevisiae catalyzes the penultimate step in the synthesis of triacylglycerol (i.e. the production of diacylglycerol by dephosphorylation of phosphatidate). The enzyme playing a major role in lipid metabolism is subject to phosphorylation (e.g. by Pho85-Pho80, Cdc28-cyclin B, and protein kinases A and C) and dephosphorylation (e.g. by Nem1-Spo7) that regulate its cellular location, catalytic activity, and stability/degradation. In this work, we show that Pah1 is a substrate for casein kinase II (CKII); its phosphorylation was time- and dose-dependent and was dependent on the concentrations of Pah1 (Km = 0.23 μm) and ATP (Km = 5.5 μm). By mass spectrometry, truncation analysis, site-directed mutagenesis, phosphopeptide mapping, and phosphoamino acid analysis, we identified that >90% of its phosphorylation occurs on Thr-170, Ser-250, Ser-313, Ser-705, Ser-814, and Ser-818. The CKII-phosphorylated Pah1 was a substrate for the Nem1-Spo7 protein phosphatase and was degraded by the 20S proteasome. The prephosphorylation of Pah1 by protein kinase A or protein kinase C reduced its subsequent phosphorylation by CKII. The prephosphorylation of Pah1 by CKII reduced its subsequent phosphorylation by protein kinase A but not by protein kinase C. The expression of Pah1 with combined mutations of S705D and 7A, which mimic its phosphorylation by CKII and lack of phosphorylation by Pho85-Pho80, caused an increase in triacylglycerol content and lipid droplet number in cells expressing the Nem1-Spo7 phosphatase complex.
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Affiliation(s)
- Lu-Sheng Hsieh
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Wen-Min Su
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Gil-Soo Han
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - George M Carman
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
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170
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Bates PD. Understanding the control of acyl flux through the lipid metabolic network of plant oil biosynthesis. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:1214-1225. [PMID: 27003249 DOI: 10.1016/j.bbalip.2016.03.021] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 03/10/2016] [Accepted: 03/11/2016] [Indexed: 10/22/2022]
Abstract
Plant oil biosynthesis involves a complex metabolic network with multiple subcellular compartments, parallel pathways, cycles, and pathways that have a dual function to produce essential membrane lipids and triacylglycerol. Modern molecular biology techniques provide tools to alter plant oil compositions through bioengineering, however with few exceptions the final composition of triacylglycerol cannot be predicted. One reason for limited success in oilseed bioengineering is the inadequate understanding of how to control the flux of fatty acids through various fatty acid modification, and triacylglycerol assembly pathways of the lipid metabolic network. This review focuses on the mechanisms of acyl flux through the lipid metabolic network, and highlights where uncertainty resides in our understanding of seed oil biosynthesis. This article is part of a Special Issue entitled: Plant Lipid Biology edited by Kent D. Chapman and Ivo Feussner.
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Affiliation(s)
- Philip D Bates
- Department of Chemistry and Biochemistry, The University of Southern Mississippi, 118 College Dr. #5043, Hattiesburg, MS 39406-0001, United States.
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171
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Jiao XL, Jing JJ, Qiao LY, Liu JH, Li LA, Zhang J, Jia XL, Liu WZ. Ontogenetic Expression of Lpin2 and Lpin3 Genes and Their Associations with Traits in Two Breeds of Chinese Fat-tailed Sheep. ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES 2016; 29:333-42. [PMID: 26950863 PMCID: PMC4811783 DOI: 10.5713/ajas.15.0467] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 07/17/2015] [Accepted: 09/10/2015] [Indexed: 12/14/2022]
Abstract
Lipins play dual function in lipid metabolism by serving as phosphatidate phosphatase and transcriptional co-regulators of gene expression. Mammalian lipin proteins consist of lipin1, lipin2, and lipin3 and are encoded by their respective genes Lpin1, Lpin2, and Lpin3. To date, most studies are concerned with Lpin1, only a few have addressed Lpin2 and Lpin3. Ontogenetic expression of Lpin2 and Lpin3 and their associations with traits would help to explore their molecular and physiological functions in sheep. In this study, 48 animals with an equal number of males and females each for both breeds of fat-tailed sheep such as Guangling Large Tailed (GLT) and Small Tailed Han (STH) were chosen to evaluate the ontogenetic expression of Lpin2 and Lpin3 from eight different tissues and months of age by quantitative real-time polymerase chain reaction (PCR). Associations between gene expression and slaughter and tail traits were also analyzed. The results showed that Lpin2 mRNA was highly expressed in perirenal and tail fats, and was also substantially expressed in liver, kidney, reproductive organs (testis and ovary), with the lowest levels in small intestine and femoral biceps. Lpin3 mRNA was prominently expressed in liver and small intestine, and was also expressed at high levels in kidney, perirenal and tail fats as well as reproductive organs (testis and ovary), with the lowest level in femoral biceps. Global expression of Lpin2 and Lpin3 in GLT both were significantly higher than those in STH. Spatiotemporal expression showed that the highest levels of Lpin2 expression occurred at 10 months of age in two breeds of sheep, with the lowest expression at 2 months of age in STH and at 8 months of age in GLT. The greatest levels of Lpin3 expression occurred at 4 months of age in STH and at 10 months of age in GLT, with the lowest expression at 12 months of age in STH and at 8 months of age in GLT. Breed and age significantly influenced the tissue expression patterns of Lpin2 and Lpin3, respectively, and sex significantly influenced the spatiotemporal expression patterns of Lpin3. Meanwhile, Lpin2 and Lpin3 mRNA expression both showed significant correlations with slaughter and tail traits, and the associations appear to be related with the ontogenetic expression as well as the potential functions of lipin2 and lipin3 in sheep.
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Affiliation(s)
- Xiao-Li Jiao
- College of Animal Science and Technology, Shanxi Agricultural University, Taigu 030-801, China ; College of Animal Science and Veterinary medicine, Tianjin Agricultural University, Tianjin 300-384, China
| | - Jiong-Jie Jing
- College of Animal Science and Technology, Shanxi Agricultural University, Taigu 030-801, China
| | - Li-Ying Qiao
- College of Animal Science and Technology, Shanxi Agricultural University, Taigu 030-801, China
| | - Jian-Hua Liu
- College of Animal Science and Technology, Shanxi Agricultural University, Taigu 030-801, China
| | - Liu-An Li
- College of Animal Science and Veterinary medicine, Tianjin Agricultural University, Tianjin 300-384, China
| | - Jing Zhang
- College of Animal Science and Technology, Shanxi Agricultural University, Taigu 030-801, China
| | - Xia-Li Jia
- College of Animal Science and Technology, Shanxi Agricultural University, Taigu 030-801, China
| | - Wen-Zhong Liu
- College of Animal Science and Technology, Shanxi Agricultural University, Taigu 030-801, China
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172
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Schmoll M, Dattenböck C, Carreras-Villaseñor N, Mendoza-Mendoza A, Tisch D, Alemán MI, Baker SE, Brown C, Cervantes-Badillo MG, Cetz-Chel J, Cristobal-Mondragon GR, Delaye L, Esquivel-Naranjo EU, Frischmann A, Gallardo-Negrete JDJ, García-Esquivel M, Gomez-Rodriguez EY, Greenwood DR, Hernández-Oñate M, Kruszewska JS, Lawry R, Mora-Montes HM, Muñoz-Centeno T, Nieto-Jacobo MF, Nogueira Lopez G, Olmedo-Monfil V, Osorio-Concepcion M, Piłsyk S, Pomraning KR, Rodriguez-Iglesias A, Rosales-Saavedra MT, Sánchez-Arreguín JA, Seidl-Seiboth V, Stewart A, Uresti-Rivera EE, Wang CL, Wang TF, Zeilinger S, Casas-Flores S, Herrera-Estrella A. The Genomes of Three Uneven Siblings: Footprints of the Lifestyles of Three Trichoderma Species. Microbiol Mol Biol Rev 2016; 80:205-327. [PMID: 26864432 PMCID: PMC4771370 DOI: 10.1128/mmbr.00040-15] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The genus Trichoderma contains fungi with high relevance for humans, with applications in enzyme production for plant cell wall degradation and use in biocontrol. Here, we provide a broad, comprehensive overview of the genomic content of these species for "hot topic" research aspects, including CAZymes, transport, transcription factors, and development, along with a detailed analysis and annotation of less-studied topics, such as signal transduction, genome integrity, chromatin, photobiology, or lipid, sulfur, and nitrogen metabolism in T. reesei, T. atroviride, and T. virens, and we open up new perspectives to those topics discussed previously. In total, we covered more than 2,000 of the predicted 9,000 to 11,000 genes of each Trichoderma species discussed, which is >20% of the respective gene content. Additionally, we considered available transcriptome data for the annotated genes. Highlights of our analyses include overall carbohydrate cleavage preferences due to the different genomic contents and regulation of the respective genes. We found light regulation of many sulfur metabolic genes. Additionally, a new Golgi 1,2-mannosidase likely involved in N-linked glycosylation was detected, as were indications for the ability of Trichoderma spp. to generate hybrid galactose-containing N-linked glycans. The genomic inventory of effector proteins revealed numerous compounds unique to Trichoderma, and these warrant further investigation. We found interesting expansions in the Trichoderma genus in several signaling pathways, such as G-protein-coupled receptors, RAS GTPases, and casein kinases. A particularly interesting feature absolutely unique to T. atroviride is the duplication of the alternative sulfur amino acid synthesis pathway.
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Affiliation(s)
- Monika Schmoll
- Austrian Institute of Technology, Department Health and Environment, Bioresources Unit, Tulln, Austria
| | - Christoph Dattenböck
- Austrian Institute of Technology, Department Health and Environment, Bioresources Unit, Tulln, Austria
| | | | | | - Doris Tisch
- Research Division Biotechnology and Microbiology, Institute of Chemical Engineering, TU Wien, Vienna, Austria
| | - Mario Ivan Alemán
- Cinvestav, Department of Genetic Engineering, Irapuato, Guanajuato, Mexico
| | - Scott E Baker
- Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Christopher Brown
- University of Otago, Department of Biochemistry and Genetics, Dunedin, New Zealand
| | | | - José Cetz-Chel
- LANGEBIO, National Laboratory of Genomics for Biodiversity, Cinvestav-Irapuato, Guanajuato, Mexico
| | | | - Luis Delaye
- Cinvestav, Department of Genetic Engineering, Irapuato, Guanajuato, Mexico
| | | | - Alexa Frischmann
- Research Division Biotechnology and Microbiology, Institute of Chemical Engineering, TU Wien, Vienna, Austria
| | | | - Monica García-Esquivel
- LANGEBIO, National Laboratory of Genomics for Biodiversity, Cinvestav-Irapuato, Guanajuato, Mexico
| | | | - David R Greenwood
- The University of Auckland, School of Biological Sciences, Auckland, New Zealand
| | - Miguel Hernández-Oñate
- LANGEBIO, National Laboratory of Genomics for Biodiversity, Cinvestav-Irapuato, Guanajuato, Mexico
| | - Joanna S Kruszewska
- Polish Academy of Sciences, Institute of Biochemistry and Biophysics, Laboratory of Fungal Glycobiology, Warsaw, Poland
| | - Robert Lawry
- Lincoln University, Bio-Protection Research Centre, Lincoln, Canterbury, New Zealand
| | | | | | | | | | | | | | - Sebastian Piłsyk
- Polish Academy of Sciences, Institute of Biochemistry and Biophysics, Laboratory of Fungal Glycobiology, Warsaw, Poland
| | - Kyle R Pomraning
- Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Aroa Rodriguez-Iglesias
- Austrian Institute of Technology, Department Health and Environment, Bioresources Unit, Tulln, Austria
| | | | | | - Verena Seidl-Seiboth
- Research Division Biotechnology and Microbiology, Institute of Chemical Engineering, TU Wien, Vienna, Austria
| | | | | | - Chih-Li Wang
- National Chung-Hsing University, Department of Plant Pathology, Taichung, Taiwan
| | - Ting-Fang Wang
- Academia Sinica, Institute of Molecular Biology, Taipei, Taiwan
| | - Susanne Zeilinger
- Research Division Biotechnology and Microbiology, Institute of Chemical Engineering, TU Wien, Vienna, Austria University of Innsbruck, Institute of Microbiology, Innsbruck, Austria
| | | | - Alfredo Herrera-Estrella
- LANGEBIO, National Laboratory of Genomics for Biodiversity, Cinvestav-Irapuato, Guanajuato, Mexico
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173
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Hung CH, Kanehara K, Nakamura Y. In vivo Reconstitution of Algal Triacylglycerol Production in Saccharomyces cerevisiae. Front Microbiol 2016; 7:70. [PMID: 26913021 PMCID: PMC4753380 DOI: 10.3389/fmicb.2016.00070] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 01/15/2016] [Indexed: 11/16/2022] Open
Abstract
The current fascination with algal biofuel production stems from a high lipid biosynthetic capacity and little conflict with land plant cultivation. However, the mechanisms which enable algae to accumulate massive oil remain elusive. An enzyme for triacylglycerol (TAG) biosynthesis in Chlamydomonas reinhardtii, CrDGTT2, can produce a large amount of TAG when expressed in yeast or higher plants, suggesting a unique ability of CrDGTT2 to enhance oil production in a heterologous system. Here, we performed metabolic engineering in Saccharomyces cerevisiae by taking advantage of CrDGTT2. We suppressed membrane phospholipid biosynthesis at the log phase by mutating OPI3, enhanced TAG biosynthetic pathway at the stationary phase by overexpressing PAH1 and CrDGTT2, and suppressed TAG hydrolysis on growth resumption from the stationary phase by knocking out DGK1. The resulting engineered yeast cells accumulated about 70-fold of TAG compared with wild type cells. Moreover, TAG production was sustainable. Our results demonstrated the enhanced and sustainable TAG production in the yeast synthetic platform.
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Affiliation(s)
- Chun-Hsien Hung
- Institute of Plant and Microbial Biology, Academia Sinica Taipei, Taiwan
| | - Kazue Kanehara
- Institute of Plant and Microbial Biology, Academia Sinica Taipei, Taiwan
| | - Yuki Nakamura
- Institute of Plant and Microbial Biology, Academia SinicaTaipei, Taiwan; Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology AgencySaitama, Japan
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174
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Makarova M, Gu Y, Chen JS, Beckley JR, Gould KL, Oliferenko S. Temporal Regulation of Lipin Activity Diverged to Account for Differences in Mitotic Programs. Curr Biol 2016; 26:237-243. [PMID: 26774782 PMCID: PMC4728079 DOI: 10.1016/j.cub.2015.11.061] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 10/27/2015] [Accepted: 11/17/2015] [Indexed: 11/03/2022]
Abstract
Eukaryotes remodel the nucleus during mitosis using a variety of mechanisms that differ in the timing and the extent of nuclear envelope (NE) breakdown. Here, we probe the principles enabling this functional diversity by exploiting the natural divergence in NE management strategies between the related fission yeasts Schizosaccharomyces pombe and Schizosaccharomyces japonicus [1-3]. We show that inactivation of Ned1, the phosphatidic acid phosphatase of the lipin family, by CDK phosphorylation is both necessary and sufficient to promote NE expansion required for "closed" mitosis in S. pombe. In contrast, Ned1 is not regulated during division in S. japonicus, thus limiting membrane availability and necessitating NE breakage. Interspecies gene swaps result in phenotypically normal divisions with the S. japonicus lipin acquiring an S. pombe-like mitotic phosphorylation pattern. Our results provide experimental evidence for the mitotic regulation of phosphatidic acid flux and suggest that the regulatory networks governing lipin activity diverged in evolution to give rise to strikingly dissimilar mitotic programs.
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Affiliation(s)
- Maria Makarova
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
| | - Ying Gu
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
| | - Jun-Song Chen
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - Janel Renée Beckley
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - Kathleen Louise Gould
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - Snezhana Oliferenko
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK.
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175
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Xu C, Andre C, Fan J, Shanklin J. Cellular Organization of Triacylglycerol Biosynthesis in Microalgae. Subcell Biochem 2016; 86:207-221. [PMID: 27023237 DOI: 10.1007/978-3-319-25979-6_9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Eukaryotic cells are characterized by compartmentalization and specialization of metabolism within membrane-bound organelles. Nevertheless, many fundamental processes extend across multiple subcellular compartments. Here, we describe and assess the pathways and cellular organization of triacylglycerol biosynthesis in microalgae. In particular, we emphases the dynamic interplay among the endoplasmic reticulum, lipid droplets and chloroplasts in acyl remodeling and triacylglycerol accumulation under nitrogen starvation in the model alga Chlamydomonas reinhardtii.
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Affiliation(s)
- Changcheng Xu
- Biology Department, Brookhaven National Laboratory, Upton, NY, 11973, USA.
| | - Carl Andre
- Biology Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Jilian Fan
- Biology Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - John Shanklin
- Biology Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
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176
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Córcoles-Sáez I, Hernández ML, Martínez-Rivas JM, Prieto JA, Randez-Gil F. Characterization of the S. cerevisiae inp51 mutant links phosphatidylinositol 4,5-bisphosphate levels with lipid content, membrane fluidity and cold growth. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1861:213-26. [PMID: 26724696 DOI: 10.1016/j.bbalip.2015.12.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 12/15/2015] [Accepted: 12/18/2015] [Indexed: 11/30/2022]
Abstract
Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and its derivatives diphosphoinositol phosphates (DPIPs) play key signaling and regulatory roles. However, a direct function of these molecules in lipid and membrane homeostasis remains obscure. Here, we have studied the cold tolerance phenotype of yeast cells lacking the Inp51-mediated phosphoinositide-5-phosphatase. Genetic and biochemical approaches showed that increased metabolism of PI(4,5)P2 reduces the activity of the Pho85 kinase by increasing the levels of the DPIP isomer 1-IP7. This effect was key in the cold tolerance phenotype. Indeed, pho85 mutant cells grew better than the wild-type at 15 °C, and lack of this kinase abolished the inp51-mediated cold phenotype. Remarkably, reduced Pho85 function by loss of Inp51 affected the activity of the Pho85-regulated target Pah1, the yeast phosphatidate phosphatase. Cells lacking Inp51 showed reduced Pah1 abundance, derepression of an INO1-lacZ reporter, decreased content of triacylglycerides and elevated levels of phosphatidate, hallmarks of the pah1 mutant. However, the inp51 phenotype was not associated to low Pah1 activity since deletion of PAH1 caused cold sensitivity. In addition, the inp51 mutant exhibited features not shared by pah1, including a 40%-reduction in total lipid content and decreased membrane fluidity. These changes may influence the activity of membrane-anchored and/or associated proteins since deletion of INP51 slows down the transit to the vacuole of the fluorescent dye FM4-64. In conclusion, our work supports a model in which changes in the PI(4,5)P2 pool affect the 1-IP7 levels modulating the activity of Pho85, Pah1 and likely additional Pho85-controlled targets, and regulate lipid composition and membrane properties.
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Affiliation(s)
- Isaac Córcoles-Sáez
- Instituto de Agroquímica y Tecnología de los Alimentos, Consejo Superior de Investigaciones Científicas (CSIC), Paterna, Valencia, Spain
| | - Maria Luisa Hernández
- Instituto de la Grasa, Consejo Superior de Investigaciones Científicas (CSIC), Sevilla, Spain
| | | | - Jose A Prieto
- Instituto de Agroquímica y Tecnología de los Alimentos, Consejo Superior de Investigaciones Científicas (CSIC), Paterna, Valencia, Spain
| | - Francisca Randez-Gil
- Instituto de Agroquímica y Tecnología de los Alimentos, Consejo Superior de Investigaciones Científicas (CSIC), Paterna, Valencia, Spain.
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177
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Jaradat SA, Amayreh W, Al-Qa'qa' K, Krayyem J. Molecular analysis of LPIN1 in Jordanian patients with rhabdomyolysis. Meta Gene 2015; 7:90-4. [PMID: 26909335 PMCID: PMC4733219 DOI: 10.1016/j.mgene.2015.12.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 09/15/2015] [Accepted: 12/02/2015] [Indexed: 12/31/2022] Open
Abstract
Recessive mutations in LPIN1, which encodes a phosphatidate phosphatase enzyme, are a frequent cause of severe rhabdomyolysis in childhood. Hence, we sequenced the 19 coding exons of the gene in eight patients with recurrent hereditary myoglobinuria from four unrelated families in Jordan. The long-term goal is to facilitate molecular genetic diagnosis without the need for invasive procedures such as muscle biopsies. Three different mutations were detected, including the novel missense mutation c.2395G>C (Gly799Arg), which was found in two families. The two other mutations, c.2174G>A (Arg725His) and c.1162C>T (Arg388X), have been previously identified, and were found to cosegregate with the disease phenotype in the other two families. Intriguingly, patients homozygous for Arg725His were also homozygous for the c.1828C>T (Pro610Ser) polymorphism, and were exercise-intolerant between myoglobinuria episodes. Notably, patients homozygous for Arg388X were also homozygous for the c.2250G>C silent variant (Gly750Gly). Taken together, the data provide family-based evidence linking hereditary myoglobinuria to pathogenic variations in the C-terminal lipin domain of the enzyme. This finding highlights the functional significance of this domain in the absence of structural information. This is the first analysis of LPIN1 in myoglobinuria patients of Jordanian origin, and the fourth such analysis worldwide. LPIN1 mutations were cataloged in families with hereditary myoglobinuria. A novel missense Gly799Arg mutation was identified. Arg725His, the only other known missense mutation, was confirmed to be pathogenic. Arg388X, a known nonsense mutation, was the most common among Arabic patients. Patients exercise-intolerant between myoglobinuria episodes have a second mutation.
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Affiliation(s)
- Saied A Jaradat
- Princess Haya Biotechnology Center, Jordan University of Science and Technology, Irbid 22110, Jordan
| | - Wajdi Amayreh
- Department of Pediatrics, Metabolic Genetics Clinic, Queen Rania Al-Abdullah Children's Hospital, King Hussein Medical Centre, Amman 11855, Jordan
| | - Kefah Al-Qa'qa'
- Department of Pediatrics, Metabolic Genetics Clinic, Queen Rania Al-Abdullah Children's Hospital, King Hussein Medical Centre, Amman 11855, Jordan
| | - Jan Krayyem
- Princess Haya Biotechnology Center, Jordan University of Science and Technology, Irbid 22110, Jordan
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178
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Lipid droplets, lipophagy, and beyond. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1861:793-805. [PMID: 26713677 DOI: 10.1016/j.bbalip.2015.12.010] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 12/06/2015] [Accepted: 12/17/2015] [Indexed: 02/06/2023]
Abstract
Lipids are essential components for life. Their various structural and physical properties influence diverse cellular processes and, thereby, human health. Lipids are not genetically encoded but are synthesized and modified by complex metabolic pathways, supplying energy, membranes, signaling molecules, and hormones to affect growth, physiology, and response to environmental insults. Lipid homeostasis is crucial, such that excess fatty acids (FAs) can be harmful to cells. To prevent such lipotoxicity, cells convert excess FAs into neutral lipids for storage in organelles called lipid droplets (LDs). These organelles do not simply manage lipid storage and metabolism but also are involved in protein quality management, pathogenesis, immune responses, and, potentially, neurodegeneration. In recent years, a major trend in LD biology has centered around the physiology of lipid mobilization via lipophagy of fat stored within LDs. This review summarizes key findings in LD biology and lipophagy, offering novel insights into this rapidly growing field. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.
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179
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Chae M, Jung JY, Bae IH, Kim HJ, Lee TR, Shin DW. Lipin-1 expression is critical for keratinocyte differentiation. J Lipid Res 2015; 57:563-73. [PMID: 26658689 DOI: 10.1194/jlr.m062588] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Indexed: 12/19/2022] Open
Abstract
Lipin-1 is an Mg(2+)-dependent phosphatidate phosphatase that facilitates the dephosphorylation of phosphatidic acid to generate diacylglycerol. Little is known about the expression and function of lipin-1 in normal human epidermal keratinocytes (NHEKs). Here, we demonstrate that lipin-1 is present in basal and spinous layers of the normal human epidermis, and lipin-1 expression is gradually downregulated during NHEK differentiation. Interestingly, lipin-1 knockdown (KD) inhibited keratinocyte differentiation and caused G1 arrest by upregulating p21 expression. Cell cycle arrest by p21 is required for commitment of keratinocytes to differentiation, but must be downregulated for the progress of keratinocyte differentiation. Therefore, reduced keratinocyte differentiation results from sustained upregulation of p21 by lipin-1 KD. Lipin-1 KD also decreased the phosphorylation/activation of protein kinase C (PKC)α, whereas lipin-1 overexpression increased PKCα phosphorylation. Treatment with PKCα inhibitors, like lipin-1 KD, stimulated p21 expression, while lipin-1 overexpression reduced p21 expression, implicating PKCα in lipin-1-induced regulation of p21 expression. Taken together, these results suggest that lipin-1-mediated downregulation of p21 is critical for the progress of keratinocyte differentiation after the initial commitment of keratinocytes to differentiation induced by p21, and that PKCα is involved in p21 expression regulation by lipin-1.
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Affiliation(s)
- Minjung Chae
- Bioscience Research Institute, Amorepacific Corporation R&D Center, Yongin-si, Gyeonggi-do, Republic of Korea
| | - Ji-Yong Jung
- Bioscience Research Institute, Amorepacific Corporation R&D Center, Yongin-si, Gyeonggi-do, Republic of Korea
| | - Il-Hong Bae
- Bioscience Research Institute, Amorepacific Corporation R&D Center, Yongin-si, Gyeonggi-do, Republic of Korea
| | - Hyoung-June Kim
- Bioscience Research Institute, Amorepacific Corporation R&D Center, Yongin-si, Gyeonggi-do, Republic of Korea
| | - Tae Ryong Lee
- Bioscience Research Institute, Amorepacific Corporation R&D Center, Yongin-si, Gyeonggi-do, Republic of Korea
| | - Dong Wook Shin
- Bioscience Research Institute, Amorepacific Corporation R&D Center, Yongin-si, Gyeonggi-do, Republic of Korea
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180
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Han S, Binns DD, Chang YF, Goodman JM. Dissecting seipin function: the localized accumulation of phosphatidic acid at ER/LD junctions in the absence of seipin is suppressed by Sei1p(ΔNterm) only in combination with Ldb16p. BMC Cell Biol 2015; 16:29. [PMID: 26637296 PMCID: PMC4670494 DOI: 10.1186/s12860-015-0075-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 11/26/2015] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Seipin is required for the correct assembly of cytoplasmic lipid droplets. In the absence of the yeast seipin homolog Sei1p (formerly Fld1p), droplets are slow to bud from the endoplasmic reticulum, lack the normal component of proteins on their surface, are highly heterogeneous in size and shape, often bud into the nucleus, and promote local proliferation of the endoplasmic reticulum in which they become tangled. But the mechanism by which seipin catalyzes lipid droplet formation is still uncertain. RESULTS Seipin prevents a localized accumulation of phosphatidic acid (PA puncta) at ER-droplet junctions. PA puncta were detected with three different probes: Opi1p, Spo20p(51-91) and Pah1p. A system of droplet induction was used to show that PA puncta were not present until droplets were formed; the puncta appeared regardless of whether droplets consisted of triacylglycerol or steryl ester. Deletion strains were used to demonstrate that a single phosphatidic acid-producing enzyme is not responsible for the generation of the puncta, and the puncta remain resistant to overexpression of enzymes that metabolize phosphatidic acid, suggesting that this lipid is trapped in a latent compartment. Suppression of PA puncta requires the first 14 amino acids of Sei1p (Nterm), a domain that is also important for initiation of droplet assembly. Consistent with recent evidence that Ldb16p and Sei1p form a functional unit, the PA puncta phenotype in the ldb16Δ sei1Δ strain was rescued by human seipin. Moreover, PA puncta in the sei1Δ strain expressing Sei1p(ΔNterm) was suppressed by overexpression of Ldb16p, suggesting a functional interaction of Nterm with this protein. Overexpression of both Sei1p and Ldb16p, but not Sei1p alone, is sufficient to cause a large increase in droplet number. However, Ldb16p alone increases triacylglycerol accumulation in the ldb16Δ sei1Δ background. CONCLUSION We hypothesize that seipin prevents formation of membranes with extreme curvature at endoplasmic reticulum/droplet junctions that would attract phosphatidic acid. While Ldb16p alone can affect triacylglycerol accumulation, proper droplet formation requires the collaboration of Sei1p and Ldb16.
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Affiliation(s)
- Sungwon Han
- Department of Pharmacology, University of Texas Southwestern Medical School, Dallas, TX, 75390-9041, USA
| | - Derk D Binns
- Department of Pharmacology, University of Texas Southwestern Medical School, Dallas, TX, 75390-9041, USA
| | - Yu-Fang Chang
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853-2703, USA
| | - Joel M Goodman
- Department of Pharmacology, University of Texas Southwestern Medical School, Dallas, TX, 75390-9041, USA.
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181
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Wolinski H, Kohlwein SD. Microscopic and spectroscopic techniques to investigate lipid droplet formation and turnover in yeast. Methods Mol Biol 2015; 1270:289-305. [PMID: 25702125 DOI: 10.1007/978-1-4939-2309-0_21] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In spite of some progress in understanding the molecular basis of lipid-associated disorders, major questions about the regulation of synthesis and degradation of lipids and the interaction of these processes with other aspects of cellular physiology are still unresolved. Studies in reference organisms such as various yeast species, the fruit fly Drosophila melanogaster, or the nematode Caenorhabditis elegans complement efforts in mouse models as well as clinical studies in humans to address these questions. Imaging techniques play a pivotal role in understanding lipid droplet biology, and the implementation of imaging-based high-content screens of mutant collections has led to the identification of novel molecular players. This study focuses on novel fluorescent probes as well as spectroscopic imaging techniques to investigate lipid droplet formation and turnover in yeast. The application and limitations of such techniques in understanding lipid storage and turnover are discussed.
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Affiliation(s)
- Heimo Wolinski
- Institute of Molecular Biosciences, BioTechMed-Graz, University of Graz, Humboldtstrasse 50/II, 8010, Graz, Austria
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182
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Meijer IA, Sasarman F, Maftei C, Rossignol E, Vanasse M, Major P, Mitchell GA, Brunel-Guitton C. LPIN1 deficiency with severe recurrent rhabdomyolysis and persistent elevation of creatine kinase levels due to chromosome 2 maternal isodisomy. Mol Genet Metab Rep 2015. [PMID: 28649549 PMCID: PMC5471397 DOI: 10.1016/j.ymgmr.2015.10.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Fatty acid oxidation disorders and lipin-1 deficiency are the commonest genetic causes of rhabdomyolysis in children. We describe a lipin-1-deficient boy with recurrent, severe rhabdomyolytic episodes from the age of 4 years. Analysis of the LPIN1 gene that encodes lipin-1 revealed a novel homozygous frameshift mutation in exon 9, c.1381delC (p.Leu461SerfsX47), and complete uniparental isodisomy of maternal chromosome 2. This mutation is predicted to cause complete lipin-1 deficiency. The patient had six rhabdomyolytic crises, with creatine kinase (CK) levels up to 300,000 U/L (normal, 30 to 200). Plasma CK remained elevated between crises. A treatment protocol was instituted, with early aggressive monitoring, hydration, electrolyte replacement and high caloric, high carbohydrate intake. The patient received dexamethasone during two crises, which was well-tolerated and in these episodes, peak CK values were lower than in preceding episodes. Studies of anti-inflammatory therapy may be indicated in lipin-1 deficiency.
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Affiliation(s)
- I A Meijer
- Division of Pediatric Neurology, Department of Pediatrics, Université de Montréal, and CHU Sainte Justine, 3175 Côte Sainte-Catherine, Montreal, Quebec H3T 1C5, Canada
| | - F Sasarman
- Division of Biochemical Genetics Laboratory, Université de Montréal and CHU Sainte Justine, 3175 Côte Sainte-Catherine, Montreal, Quebec H3T 1C5, Canada
| | - C Maftei
- Medical Genetics, Department of Pediatrics, Université de Montréal and CHU Sainte Justine, 3175 Côte Sainte-Catherine, Montreal, Quebec H3T 1C5, Canada
| | - E Rossignol
- Division of Pediatric Neurology, Department of Pediatrics, Université de Montréal, and CHU Sainte Justine, 3175 Côte Sainte-Catherine, Montreal, Quebec H3T 1C5, Canada
| | - M Vanasse
- Division of Pediatric Neurology, Department of Pediatrics, Université de Montréal, and CHU Sainte Justine, 3175 Côte Sainte-Catherine, Montreal, Quebec H3T 1C5, Canada
| | - P Major
- Division of Pediatric Neurology, Department of Pediatrics, Université de Montréal, and CHU Sainte Justine, 3175 Côte Sainte-Catherine, Montreal, Quebec H3T 1C5, Canada
| | - G A Mitchell
- Medical Genetics, Department of Pediatrics, Université de Montréal and CHU Sainte Justine, 3175 Côte Sainte-Catherine, Montreal, Quebec H3T 1C5, Canada
| | - C Brunel-Guitton
- Division of Biochemical Genetics Laboratory, Université de Montréal and CHU Sainte Justine, 3175 Côte Sainte-Catherine, Montreal, Quebec H3T 1C5, Canada.,Medical Genetics, Department of Pediatrics, Université de Montréal and CHU Sainte Justine, 3175 Côte Sainte-Catherine, Montreal, Quebec H3T 1C5, Canada
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183
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Barbosa AD, Sembongi H, Su WM, Abreu S, Reggiori F, Carman GM, Siniossoglou S. Lipid partitioning at the nuclear envelope controls membrane biogenesis. Mol Biol Cell 2015; 26:3641-57. [PMID: 26269581 PMCID: PMC4603934 DOI: 10.1091/mbc.e15-03-0173] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 07/22/2015] [Accepted: 08/06/2015] [Indexed: 12/11/2022] Open
Abstract
Partitioning of lipid precursors between membranes and storage is crucial for cell growth, and its disruption underlies pathologies such as cancer, obesity, and type 2 diabetes. However, the mechanisms and signals that regulate this process are largely unknown. In yeast, lipid precursors are mainly used for phospholipid synthesis in nutrient-rich conditions in order to sustain rapid proliferation but are redirected to triacylglycerol (TAG) stored in lipid droplets during starvation. Here we investigate how cells reprogram lipid metabolism in the endoplasmic reticulum. We show that the conserved phosphatidate (PA) phosphatase Pah1, which generates diacylglycerol from PA, targets a nuclear membrane subdomain that is in contact with growing lipid droplets and mediates TAG synthesis. We find that cytosol acidification activates the master regulator of Pah1, the Nem1-Spo7 complex, thus linking Pah1 activity to cellular metabolic status. In the absence of TAG storage capacity, Pah1 still binds the nuclear membrane, but lipid precursors are redirected toward phospholipids, resulting in nuclear deformation and a proliferation of endoplasmic reticulum membrane. We propose that, in response to growth signals, activation of Pah1 at the nuclear envelope acts as a switch to control the balance between membrane biogenesis and lipid storage.
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Affiliation(s)
- Antonio Daniel Barbosa
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
| | - Hiroshi Sembongi
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
| | - Wen-Min Su
- Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, NJ 08901
| | - Susana Abreu
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, 9713 A Groningen, Netherlands
| | - Fulvio Reggiori
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, 9713 A Groningen, Netherlands
| | - George M Carman
- Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, NJ 08901
| | - Symeon Siniossoglou
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
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184
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Park Y, Han GS, Mileykovskaya E, Garrett TA, Carman GM. Altered Lipid Synthesis by Lack of Yeast Pah1 Phosphatidate Phosphatase Reduces Chronological Life Span. J Biol Chem 2015; 290:25382-94. [PMID: 26338708 DOI: 10.1074/jbc.m115.680314] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Indexed: 01/20/2023] Open
Abstract
In Saccharomyces cerevisiae, Pah1 phosphatidate phosphatase, which catalyzes the dephosphorylation of phosphatidate to yield diacylglycerol, plays a crucial role in the synthesis of the storage lipid triacylglycerol. This evolutionarily conserved enzyme also plays a negative regulatory role in controlling de novo membrane phospholipid synthesis through its consumption of phosphatidate. We found that the pah1Δ mutant was defective in the utilization of non-fermentable carbon sources but not in oxidative phosphorylation; the mutant did not exhibit major changes in oxygen consumption rate, mitochondrial membrane potential, F1F0-ATP synthase activity, or gross mitochondrial morphology. The pah1Δ mutant contained an almost normal complement of major mitochondrial phospholipids with some alterations in molecular species. Although oxidative phosphorylation was not compromised in the pah1Δ mutant, the cellular levels of ATP in quiescent cells were reduced by 2-fold, inversely correlating with a 4-fold increase in membrane phospholipids. In addition, the quiescent pah1Δ mutant cells had 3-fold higher levels of mitochondrial superoxide and cellular lipid hydroperoxides, had reduced activities of superoxide dismutase 2 and catalase, and were hypersensitive to hydrogen peroxide. Consequently, the pah1Δ mutant had a shortened chronological life span. In addition, the loss of Tsa1 thioredoxin peroxidase caused a synthetic growth defect with the pah1Δ mutation. The shortened chronological life span of the pah1Δ mutant along with its growth defect on non-fermentable carbon sources and hypersensitivity to hydrogen peroxide was suppressed by the loss of Dgk1 diacylglycerol kinase, indicating that the underpinning of pah1Δ mutant defects was the excess synthesis of membrane phospholipids.
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Affiliation(s)
- Yeonhee Park
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Gil-Soo Han
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Eugenia Mileykovskaya
- the Department of Biochemistry and Molecular Biology, University of Texas-Houston Medical School, Houston, Texas 77030, and
| | - Teresa A Garrett
- the Department of Chemistry, Vassar College, Poughkeepsie, New York 12604
| | - George M Carman
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901,
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185
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Yang M, Nickels JT. MOGAT2: A New Therapeutic Target for Metabolic Syndrome. Diseases 2015; 3:176-192. [PMID: 28943619 PMCID: PMC5548241 DOI: 10.3390/diseases3030176] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 08/13/2015] [Accepted: 08/17/2015] [Indexed: 12/26/2022] Open
Abstract
Metabolic syndrome is an ever-increasing health problem among the world’s population. It is a group of intertwined maladies that includes obesity, hypertriglyceridemia, hypertension, nonalcoholic fatty liver disease (NAFLD), and diabetes mellitus type II (T2D). There is a direct correlation between high triacylglycerol (triglyceride; TAG) level and severity of metabolic syndrome. Thus, controlling the synthesis of TAG will have a great impact on overall systemic lipid metabolism and thus metabolic syndrome progression. The Acyl-CoA: monoacylglycerolacyltransferase (MGAT) family has three members (MGAT1, -2, and -3) that catalyze the first step in TAG production, conversion of monoacylglycerol (MAG) to diacylglycerol (DAG). TAG is then directly synthesized from DAG by a Acyl-CoA: diacylglycerolacyltransferase (DGAT). The conversion of MAG → DAG → TAG is the major pathway for the production of TAG in the small intestine, and produces TAG to a lesser extent in the liver. Transgenic and pharmacological studies in mice have demonstrated the beneficial effects of MGAT inhibition as a therapy for treating several metabolic diseases, including obesity, insulin resistance, T2D, and NAFLD. In this review, the significance of several properties of MGAT physiology, including tissue expression pattern and its relationship to overall TAG metabolism, enzymatic biochemical properties and their effects on drug discovery, and finally what is the current knowledge about MGAT small molecule inhibitors and their efficacy will be discussed. Overall, this review highlights the therapeutic potential of inhibiting MGAT for lowering TAG synthesis and whether this avenue of drug discovery warrants further clinical investigation.
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Affiliation(s)
- Muhua Yang
- Institute of Metabolic Disorders, Genesis Biotechnology Group, Hamilton, NJ 08691, USA.
| | - Joseph T Nickels
- Institute of Metabolic Disorders, Genesis Biotechnology Group, Hamilton, NJ 08691, USA.
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186
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Yadav KK, Singh N, Rajasekharan R. PHO4 transcription factor regulates triacylglycerol metabolism under low-phosphate conditions in Saccharomyces cerevisiae. Mol Microbiol 2015; 98:456-72. [PMID: 26179227 DOI: 10.1111/mmi.13133] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/14/2015] [Indexed: 02/01/2023]
Abstract
In Saccharomyces cerevisiae, PHM8 encodes a phosphatase that catalyses the dephosphorylation of lysophosphatidic acids to monoacylglycerol and nucleotide monophosphate to nucleoside and releases free phosphate. In this report, we investigated the role of PHM8 in triacylglycerol metabolism and its transcriptional regulation by a phosphate responsive transcription factor Pho4p under low-phosphate conditions. We found that the wild-type (BY4741) cells accumulate triacylglycerol and the expression of PHM8 was high under low-phosphate conditions. Overexpression of PHM8 in the wild-type, phm8Δ and quadruple phosphatase mutant (pah1Δdpp1Δlpp1Δapp1Δ) caused an increase in the triacylglycerol levels. However, the introduction of the PHM8 deletion into the quadruple phosphatase mutant resulted in a reduction in triacylglycerol levels and LPA phosphatase activity. The transcriptional activator Pho4p binds to the PHM8 promoter under low-phosphate conditions, activating PHM8 expression, which leads to the formation of monoacylglycerol from LPA. The synthesized monoacylglycerol is acylated to diacylglycerol by Dga1p, which is further acylated to triacylglycerol by the same enzyme.
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Affiliation(s)
- Kamlesh Kumar Yadav
- Lipidomic Centre, Department of Lipid Science, CSIR-Central Food Technological Research Institute (CFTRI), Mysore, Karnataka, 570020, India.,Academy of Scientific and Innovative Research (AcSIR), CSIR-CFTRI Campus
| | - Neelima Singh
- Lipidomic Centre, Department of Lipid Science, CSIR-Central Food Technological Research Institute (CFTRI), Mysore, Karnataka, 570020, India.,Academy of Scientific and Innovative Research (AcSIR), CSIR-CFTRI Campus
| | - Ram Rajasekharan
- Lipidomic Centre, Department of Lipid Science, CSIR-Central Food Technological Research Institute (CFTRI), Mysore, Karnataka, 570020, India.,Academy of Scientific and Innovative Research (AcSIR), CSIR-CFTRI Campus
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187
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Seipin is involved in the regulation of phosphatidic acid metabolism at a subdomain of the nuclear envelope in yeast. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:1450-64. [PMID: 26275961 DOI: 10.1016/j.bbalip.2015.08.003] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2015] [Revised: 07/17/2015] [Accepted: 08/10/2015] [Indexed: 12/31/2022]
Abstract
Yeast Fld1 and Ldb16 resemble mammalian seipin, implicated in neutral lipid storage. Both proteins form a complex at the endoplasmic reticulum-lipid droplet (LD) interface. Malfunction of this complex either leads to LD clustering or to the generation of supersized LD (SLD) in close vicinity to the nuclear envelope, in response to altered phospholipid (PL) composition. We show that similar to mutants lacking Fld1, deletion of LDB16 leads to abnormal proliferation of a subdomain of the nuclear envelope, which is tightly associated with clustered LD. The human lipin-1 ortholog, the PAH1 encoded phosphatidic acid (PA) phosphatase, and its activator Nem1 are highly enriched at this site. The specific accumulation of PA-binding marker proteins indicates a local enrichment of PA in the fld1 and ldb16 mutants. Furthermore, we demonstrate that clustered LD in fld1 or ldb16 mutants are transformed to SLD if phosphatidylcholine synthesis is compromised by additional deletion of the phosphatidylethanolamine methyltransferase, Cho2. Notably, treatment of wild-type cells with oleate induced a similar LD clustering and nuclear membrane proliferation phenotype as observed in fld1 and ldb16 mutants. These data suggest that the Fld1-Ldb16 complex affects PA homeostasis at an LD-forming subdomain of the nuclear envelope. Lack of Fld1-Ldb16 leads to locally elevated PA levels that induce an abnormal proliferation of nER membrane structures and the clustering of associated LD. We suggest that the formation of SLD is a consequence of locally altered PL metabolism at this site.
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188
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Does Diacylglycerol Accumulation in Fatty Liver Disease Cause Hepatic Insulin Resistance? BIOMED RESEARCH INTERNATIONAL 2015; 2015:104132. [PMID: 26273583 PMCID: PMC4529893 DOI: 10.1155/2015/104132] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 01/27/2015] [Indexed: 01/04/2023]
Abstract
Numerous studies conducted on obese humans and various rodent models of obesity have identified a correlation between hepatic lipid content and the development of insulin resistance in liver and other tissues. Despite a large body of the literature on this topic, the cause and effect relationship between hepatic steatosis and insulin resistance remains controversial. If, as many believe, lipid aggregation in liver drives insulin resistance and other metabolic abnormalities, there are significant unanswered questions as to which lipid mediators are causative in this cascade. Several published papers have now correlated levels of diacylglycerol (DAG), the penultimate intermediate in triglyceride synthesis, with development of insulin resistance and have postulated that this occurs via activation of protein kinase C signaling. Although many studies have confirmed this relationship, many others have reported a disconnect between DAG content and insulin resistance. It has been postulated that differences in methods for DAG measurement, DAG compartmentalization within the cell, or fatty acid composition of the DAG may explain these discrepancies. The purpose of this review is to compare and contrast some of the relevant findings in this area and to discuss a number of unanswered questions regarding the relationship between DAG and insulin resistance.
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189
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Hamel Y, Mamoune A, Mauvais FX, Habarou F, Lallement L, Romero NB, Ottolenghi C, de Lonlay P. Acute rhabdomyolysis and inflammation. J Inherit Metab Dis 2015; 38:621-8. [PMID: 25778939 DOI: 10.1007/s10545-015-9827-7] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 02/10/2015] [Accepted: 02/11/2015] [Indexed: 02/07/2023]
Abstract
Rhabdomyolysis results from the rapid breakdown of skeletal muscle fibers, which leads to leakage of potentially toxic cellular content into the systemic circulation. Acquired causes by direct injury to the sarcolemma are most frequent. The inherited causes are: i) metabolic with failure of energy production, including mitochondrial fatty acid ß-oxidation defects, LPIN1 mutations, inborn errors of glycogenolysis and glycolysis, more rarely mitochondrial respiratory chain deficiency, purine defects and peroxysomal α-methyl-acyl-CoA-racemase defect (AMACR), ii) structural causes with muscle dystrophies and myopathies, iii) calcium pump disorder with RYR1 gene mutations, iv) inflammatory causes with myositis. Irrespective of the cause of rhabdomyolysis, the pathology follows a common pathway, either by the direct injury to sarcolemma by increased intracellular calcium concentration (acquired causes) or by the failure of energy production (inherited causes), which leads to fiber necrosis. Rhabdomyolysis are frequently precipitated by febrile illness or exercise. These conditions are associated with two events, elevated temperature and high circulating levels of pro-inflammatory mediators such as cytokines and chemokines. To illustrate these points in the context of energy metabolism, protein thermolability and the potential benefits of arginine therapy, we focus on a rare cause of rhabdomyolysis, aldolase A deficiency. In addition, our studies on lipin-1 (LPIN1) deficiency raise the possibility that several diseases involved in rhabdomyolysis implicate pro-inflammatory cytokines and may even represent primarily pro-inflammatory diseases. Thus, not only thermolability of mutant proteins critical for muscle function, but also pro-inflammatory cytokines per se, may lead to metabolic decompensation and rhabdomyolysis.
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Affiliation(s)
- Yamina Hamel
- Institut Imagine, Institut National de la Santé et de la Recherche Médicale, Unité 1163, 75015, Paris, France
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190
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Wang CW. Lipid droplet dynamics in budding yeast. Cell Mol Life Sci 2015; 72:2677-95. [PMID: 25894691 PMCID: PMC11113813 DOI: 10.1007/s00018-015-1903-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 04/01/2015] [Accepted: 04/07/2015] [Indexed: 10/23/2022]
Abstract
Eukaryotic cells store excess fatty acids as neutral lipids, predominantly triacylglycerols and sterol esters, in organelles termed lipid droplets (LDs) that bulge out from the endoplasmic reticulum. LDs are highly dynamic and contribute to diverse cellular functions. The catabolism of the storage lipids within LDs is channeled to multiple metabolic pathways, providing molecules for energy production, membrane building blocks, and lipid signaling. LDs have been implicated in a number of protein degradation and pathogen infection processes. LDs may be linked to prevalent human metabolic diseases and have marked potential for biofuel production. The knowledge accumulated on LDs in recent years provides a foundation for diverse, and even unexpected, future research. This review focuses on recent advances in LD research, emphasizing the diverse physiological roles of LDs in the model system of budding yeast.
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Affiliation(s)
- Chao-Wen Wang
- Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei, 11529, Taiwan,
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191
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Kuznetsova E, Nocek B, Brown G, Makarova KS, Flick R, Wolf YI, Khusnutdinova A, Evdokimova E, Jin K, Tan K, Hanson AD, Hasnain G, Zallot R, de Crécy-Lagard V, Babu M, Savchenko A, Joachimiak A, Edwards AM, Koonin EV, Yakunin AF. Functional Diversity of Haloacid Dehalogenase Superfamily Phosphatases from Saccharomyces cerevisiae: BIOCHEMICAL, STRUCTURAL, AND EVOLUTIONARY INSIGHTS. J Biol Chem 2015; 290:18678-98. [PMID: 26071590 DOI: 10.1074/jbc.m115.657916] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Indexed: 12/15/2022] Open
Abstract
The haloacid dehalogenase (HAD)-like enzymes comprise a large superfamily of phosphohydrolases present in all organisms. The Saccharomyces cerevisiae genome encodes at least 19 soluble HADs, including 10 uncharacterized proteins. Here, we biochemically characterized 13 yeast phosphatases from the HAD superfamily, which includes both specific and promiscuous enzymes active against various phosphorylated metabolites and peptides with several HADs implicated in detoxification of phosphorylated compounds and pseudouridine. The crystal structures of four yeast HADs provided insight into their active sites, whereas the structure of the YKR070W dimer in complex with substrate revealed a composite substrate-binding site. Although the S. cerevisiae and Escherichia coli HADs share low sequence similarities, the comparison of their substrate profiles revealed seven phosphatases with common preferred substrates. The cluster of secondary substrates supporting significant activity of both S. cerevisiae and E. coli HADs includes 28 common metabolites that appear to represent the pool of potential activities for the evolution of novel HAD phosphatases. Evolution of novel substrate specificities of HAD phosphatases shows no strict correlation with sequence divergence. Thus, evolution of the HAD superfamily combines the conservation of the overall substrate pool and the substrate profiles of some enzymes with remarkable biochemical and structural flexibility of other superfamily members.
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Affiliation(s)
- Ekaterina Kuznetsova
- From the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Boguslaw Nocek
- the Midwest Center for Structural Genomics and Structural Biology Center, Biosciences Division, Argonne National Laboratory, Argonne, Illinois 60439
| | - Greg Brown
- the Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada
| | - Kira S Makarova
- the National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland 20894
| | - Robert Flick
- the Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada
| | - Yuri I Wolf
- the National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland 20894
| | - Anna Khusnutdinova
- the Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada
| | - Elena Evdokimova
- the Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada
| | - Ke Jin
- the Department of Biochemistry, Research and Innovation Centre, University of Regina, Regina, Saskatchewan S4S 0A2, Canada, and
| | - Kemin Tan
- the Midwest Center for Structural Genomics and Structural Biology Center, Biosciences Division, Argonne National Laboratory, Argonne, Illinois 60439
| | - Andrew D Hanson
- the Horticultural Sciences Department, Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida 32611
| | - Ghulam Hasnain
- the Horticultural Sciences Department, Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida 32611
| | - Rémi Zallot
- the Horticultural Sciences Department, Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida 32611
| | - Valérie de Crécy-Lagard
- the Horticultural Sciences Department, Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida 32611
| | - Mohan Babu
- the Department of Biochemistry, Research and Innovation Centre, University of Regina, Regina, Saskatchewan S4S 0A2, Canada, and
| | - Alexei Savchenko
- the Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada
| | - Andrzej Joachimiak
- the Midwest Center for Structural Genomics and Structural Biology Center, Biosciences Division, Argonne National Laboratory, Argonne, Illinois 60439
| | - Aled M Edwards
- From the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada, the Midwest Center for Structural Genomics and Structural Biology Center, Biosciences Division, Argonne National Laboratory, Argonne, Illinois 60439
| | - Eugene V Koonin
- the National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland 20894
| | - Alexander F Yakunin
- the Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada,
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192
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Rhabdomyolysis-Associated Mutations in Human LPIN1 Lead to Loss of Phosphatidic Acid Phosphohydrolase Activity. JIMD Rep 2015; 23:113-22. [PMID: 25967228 DOI: 10.1007/8904_2015_440] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 04/06/2015] [Accepted: 04/08/2015] [Indexed: 12/18/2022] Open
Abstract
Rhabdomyolysis is an acute syndrome due to extensive injury of skeletal muscle. Recurrent rhabdomyolysis is often caused by inborn errors in intermediary metabolism, and recent work has suggested that mutations in the human gene encoding lipin 1 (LPIN1) may be a common cause of recurrent rhabdomyolysis in children. Lipin 1 dephosphorylates phosphatidic acid to form diacylglycerol (phosphatidic acid phosphohydrolase; PAP) and acts as a transcriptional regulatory protein to control metabolic gene expression. Herein, a 3-year-old boy with severe recurrent rhabdomyolysis was determined to be a compound heterozygote for a novel c.1904T>C (p.Leu635Pro) substitution and a previously reported genomic deletion of exons 18-19 (E766-S838_del) in LPIN1. Western blotting with patient muscle biopsy lysates demonstrated a marked reduction in lipin 1 protein, while immunohistochemical staining for lipin 1 showed abnormal subcellular localization. We cloned cDNAs to express recombinant lipin 1 proteins harboring pathogenic mutations and showed that the E766-S838_del allele was not expressed at the RNA or protein level. Lipin 1 p.Leu635Pro was expressed, but the protein was less stable, was aggregated in the cytosol, and was targeted for proteosomal degradation. Another pathogenic single amino acid substitution, lipin 1 p.Arg725His, was well expressed and retained its transcriptional regulatory function. However, both p.Leu635Pro and p.Arg725His proteins were found to be deficient in PAP activity. Kinetic analyses demonstrated a loss of catalysis rather than diminished substrate binding. These data suggest that loss of lipin 1-mediated PAP activity may be involved in the pathogenesis of rhabdomyolysis in lipin 1 deficiency.
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193
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Craddock CP, Adams N, Bryant FM, Kurup S, Eastmond PJ. PHOSPHATIDIC ACID PHOSPHOHYDROLASE Regulates Phosphatidylcholine Biosynthesis in Arabidopsis by Phosphatidic Acid-Mediated Activation of CTP:PHOSPHOCHOLINE CYTIDYLYLTRANSFERASE Activity. THE PLANT CELL 2015; 27:1251-64. [PMID: 25862304 PMCID: PMC4558698 DOI: 10.1105/tpc.15.00037] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 03/19/2015] [Indexed: 05/04/2023]
Abstract
Regulation of membrane lipid biosynthesis is critical for cell function. We previously reported that disruption of PHOSPHATIDIC ACID PHOSPHOHYDROLASE1 (PAH1) and PAH2 stimulates net phosphatidylcholine (PC) biosynthesis and proliferation of the endoplasmic reticulum (ER) in Arabidopsis thaliana. Here, we show that this response is caused specifically by a reduction in the catalytic activity of the protein and positively correlates with an accumulation of its substrate, phosphatidic acid (PA). The accumulation of PC in pah1 pah2 is suppressed by disruption of CTP:PHOSPHOCHOLINE CYTIDYLYLTRANSFERASE1 (CCT1), which encodes a key enzyme in the nucleotide pathway for PC biosynthesis. The activity of recombinant CCT1 is stimulated by lipid vesicles containing PA. Truncation of CCT1, to remove the predicted C-terminal amphipathic lipid binding domain, produced a constitutively active enzyme. Overexpression of native CCT1 in Arabidopsis has no significant effect on PC biosynthesis or ER morphology, but overexpression of the truncated constitutively active version largely replicates the pah1 pah2 phenotype. Our data establish that membrane homeostasis is regulated by lipid composition in Arabidopsis and reveal a mechanism through which the abundance of PA, mediated by PAH activity, modulates CCT activity to govern PC content.
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Affiliation(s)
- Christian P Craddock
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Nicolette Adams
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Fiona M Bryant
- Department of Plant Biology and Crop Science, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, United Kingdom
| | - Smita Kurup
- Department of Plant Biology and Crop Science, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, United Kingdom
| | - Peter J Eastmond
- Department of Plant Biology and Crop Science, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, United Kingdom
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194
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Jin HH, Jiang JG. Phosphatidic acid phosphatase and diacylglycerol acyltransferase: potential targets for metabolic engineering of microorganism oil. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2015; 63:3067-77. [PMID: 25672855 DOI: 10.1021/jf505975k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Oleaginous microorganism is becoming one of the most promising oil feedstocks for biodiesel production due to its great advantages in triglyceride (TAG) accumulation. Previous studies have shown that de novo TAG biosynthesis can be divided into two parts: the fatty acid biosynthesis pathway (the upstream part which generates acyl-CoAs) and the glycerol-3-phosphate acylation pathway (the downstream part in which three acyl groups are sequentially added onto a glycerol backbone). This review mainly focuses on two enzymes in the G3P pathway, phosphatidic acid phosphatase (PAP) and diacylglycerol acyltransferase (DGAT). The former catalyzes a dephosphorylation reaction, and the latter catalyzes a subsequent acylation reaction. Genes, functional motifs, transmembrane domains, action mechanism, and new studies of the two enzymes are discussed in detail. Furthermore, this review also covers diacylglycerol kinase, an enzyme that catalyzes the reverse reaction of diacylglycerol formation. In addition, PAP and DGAT are the conjunction points of the G3P pathway, the Kennedy pathway, and the CDP-diacylglycerol pathway (CDP-DAG pathway), and the mutual transformation between TAGs and phospholipids is discussed as well. Given that both the Kennedy and CDP-diacylglycerol pathways are in metabolic interlock (MI) with the G3P pathway, it is suggested that, via metabolic engineering, TAG accumulation can be improved by the two pathways based on the pivotal function of PAP and DGAT.
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Affiliation(s)
- Hong-Hao Jin
- College of Food and Bioengineering, South China University of Technology, Guangzhou, 510640, China
| | - Jian-Guo Jiang
- College of Food and Bioengineering, South China University of Technology, Guangzhou, 510640, China
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195
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Tang X, Benesch MGK, Brindley DN. Lipid phosphate phosphatases and their roles in mammalian physiology and pathology. J Lipid Res 2015; 56:2048-60. [PMID: 25814022 DOI: 10.1194/jlr.r058362] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Indexed: 12/20/2022] Open
Abstract
Lipid phosphate phosphatases (LPPs) are a group of enzymes that belong to a phosphatase/phosphotransferase family. Mammalian LPPs consist of three isoforms: LPP1, LPP2, and LPP3. They share highly conserved catalytic domains and catalyze the dephosphorylation of a variety of lipid phosphates, including phosphatidate, lysophosphatidate (LPA), sphingosine 1-phosphate (S1P), ceramide 1-phosphate, and diacylglycerol pyrophosphate. LPPs are integral membrane proteins, which are localized on plasma membranes with the active site on the outer leaflet. This enables the LPPs to degrade extracellular LPA and S1P, thereby attenuating their effects on the activation of surface receptors. LPP3 also exhibits noncatalytic effects at the cell surface. LPP expression on internal membranes, such as endoplasmic reticulum and Golgi, facilitates the metabolism of internal lipid phosphates, presumably on the luminal surface of these organelles. This action probably explains the signaling effects of the LPPs, which occur downstream of receptor activation. The three isoforms of LPPs show distinct and nonredundant effects in several physiological and pathological processes including embryo development, vascular function, and tumor progression. This review is intended to present an up-to-date understanding of the physiological and pathological consequences of changing the activities of the different LPPs, especially in relation to cell signaling by LPA and S1P.
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Affiliation(s)
- Xiaoyun Tang
- Signal Transduction Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2S2, Canada
| | - Matthew G K Benesch
- Signal Transduction Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2S2, Canada
| | - David N Brindley
- Signal Transduction Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2S2, Canada
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196
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Hsieh LS, Su WM, Han GS, Carman GM. Phosphorylation regulates the ubiquitin-independent degradation of yeast Pah1 phosphatidate phosphatase by the 20S proteasome. J Biol Chem 2015; 290:11467-78. [PMID: 25809482 DOI: 10.1074/jbc.m115.648659] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Indexed: 01/08/2023] Open
Abstract
Saccharomyces cerevisiae Pah1 phosphatidate phosphatase, which catalyzes the conversion of phosphatidate to diacylglycerol for triacylglycerol synthesis and simultaneously controls phosphatidate levels for phospholipid synthesis, is subject to the proteasome-mediated degradation in the stationary phase of growth. In this study, we examined the mechanism for its degradation using purified Pah1 and isolated proteasomes. Pah1 expressed in S. cerevisiae or Escherichia coli was not degraded by the 26S proteasome, but by its catalytic 20S core particle, indicating that its degradation is ubiquitin-independent. The degradation of Pah1 by the 20S proteasome was dependent on time and proteasome concentration at the pH optimum of 7.0. The 20S proteasomal degradation was conserved for human lipin 1 phosphatidate phosphatase. The degradation analysis using Pah1 truncations and its fusion with GFP indicated that proteolysis initiates at the N- and C-terminal unfolded regions. The folded region of Pah1, in particular the haloacid dehalogenase-like domain containing the DIDGT catalytic sequence, was resistant to the proteasomal degradation. The structural change of Pah1, as reflected by electrophoretic mobility shift, occurs through its phosphorylation by Pho85-Pho80, and the phosphorylation sites are located within its N- and C-terminal unfolded regions. Phosphorylation of Pah1 by Pho85-Pho80 inhibited its degradation, extending its half-life by ∼2-fold. The dephosphorylation of endogenously phosphorylated Pah1 by the Nem1-Spo7 protein phosphatase, which is highly specific for the sites phosphorylated by Pho85-Pho80, stimulated the 20S proteasomal degradation and reduced its half-life by 2.6-fold. These results indicate that the proteolysis of Pah1 by the 20S proteasome is controlled by its phosphorylation state.
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Affiliation(s)
- Lu-Sheng Hsieh
- From the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Wen-Min Su
- From the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Gil-Soo Han
- From the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - George M Carman
- From the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
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197
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Schweitzer GG, Chen Z, Gan C, McCommis KS, Soufi N, Chrast R, Mitra MS, Yang K, Gross RW, Finck BN. Liver-specific loss of lipin-1-mediated phosphatidic acid phosphatase activity does not mitigate intrahepatic TG accumulation in mice. J Lipid Res 2015; 56:848-58. [PMID: 25722343 DOI: 10.1194/jlr.m055962] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Lipin proteins (lipin 1, 2, and 3) regulate glycerolipid homeostasis by acting as phosphatidic acid phosphohydrolase (PAP) enzymes in the TG synthesis pathway and by regulating DNA-bound transcription factors to control gene transcription. Hepatic PAP activity could contribute to hepatic fat accumulation in response to physiological and pathophysiological stimuli. To examine the role of lipin 1 in regulating hepatic lipid metabolism, we generated mice that are deficient in lipin-1-encoded PAP activity in a liver-specific manner (Alb-Lpin1(-/-) mice). This allele of lipin 1 was still able to transcriptionally regulate the expression of its target genes encoding fatty acid oxidation enzymes, and the expression of these genes was not affected in Alb-Lpin1(-/-) mouse liver. Hepatic PAP activity was significantly reduced in mice with liver-specific lipin 1 deficiency. However, hepatocytes from Alb-Lpin1(-/-) mice had normal rates of TG synthesis, and steady-state hepatic TG levels were unaffected under fed and fasted conditions. Furthermore, Alb-Lpin1(-/-) mice were not protected from intrahepatic accumulation of diacylglycerol and TG after chronic feeding of a diet rich in fat and fructose. Collectively, these data demonstrate that marked deficits in hepatic PAP activity do not impair TG synthesis and accumulation under acute or chronic conditions of lipid overload.
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Affiliation(s)
| | - Zhouji Chen
- Washington University School of Medicine, St. Louis, MO 63110
| | - Connie Gan
- Washington University School of Medicine, St. Louis, MO 63110
| | - Kyle S McCommis
- Washington University School of Medicine, St. Louis, MO 63110
| | - Nisreen Soufi
- Washington University School of Medicine, St. Louis, MO 63110
| | - Roman Chrast
- Department of Medical Genetics, University of Lausanne, 1005 Lausanne, Switzerland
| | | | - Kui Yang
- Washington University School of Medicine, St. Louis, MO 63110
| | - Richard W Gross
- Washington University School of Medicine, St. Louis, MO 63110
| | - Brian N Finck
- Washington University School of Medicine, St. Louis, MO 63110
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198
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Gross DA, Silver DL. Cytosolic lipid droplets: from mechanisms of fat storage to disease. Crit Rev Biochem Mol Biol 2015; 49:304-26. [PMID: 25039762 DOI: 10.3109/10409238.2014.931337] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The lipid droplet (LD) is a phylogenetically conserved organelle. In eukaryotes, it is born from the endoplasmic reticulum, but unlike its parent organelle, LDs are the only known cytosolic organelles that are micellar in structure. LDs are implicated in numerous physiological and pathophysiological functions. Many aspects of the LD has captured the attention of diverse scientists alike and has recently led to an explosion in information on the LD biogenesis, expansion and fusion, identification of LD proteomes and diseases associated with LD biology. This review will provide a brief history of this fascinating organelle and provide some contemporary views of unanswered questions in LD biogenesis.
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Affiliation(s)
- David A Gross
- Program in Cardiovascular & Metabolic Disorders, Duke-NUS Graduate Medical School Singapore , Singapore , and
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199
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Huang Y, Zhang C, Zhang W, Zhang P, Kang X, Chen W. Variation in the chicken LPIN2 gene and association with performance traits. Br Poult Sci 2015; 56:175-83. [PMID: 25668704 DOI: 10.1080/00071668.2015.1008994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The objective of the study was to investigate the distribution of LPIN2 variants and haplotypes among breeds and perform an association analysis of the variants and haplotypes with the broiler traits in chickens. Six breeds were used to study the variation and distribution of chicken LPIN2, and an F2 resource population was used to measure growth traits, carcass traits, meat quality traits and serum biochemistry parameters. A c.-599G>A variant was located in the promoter region of LPIN2 and c.444G>A and c.1730A>T (E577D) coding variant mutations were detected. Linkage disequilibrium tests showed that these three variants were under moderate linkage disequilibrium in the 6 breeds and 7 haplotypes were constructed. The distribution of variation/haplotypes presented clear differences among breeds. Association analysis showed that c.-599G>A was associated with leg muscle weight, jejunum length, ileum length, leg muscle fibre density and leg muscle fibre diameter; c.444G>A was associated with spleen weight, ileum length, body weight at hatch and metatarsus length at 8 weeks; c.1730T>A had significant effects on chicken liver weight, heart weight, body weight at 10 weeks, serum albumin and glucose. Diplotypes were significantly associated with body weight at hatch, heart weight, pancreas weight, duodenum length, leg muscle fibre density and lactate dehydrogenase.
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Affiliation(s)
- Y Huang
- a College of Livestock Husbandry and Veterinary Engineering , Henan Agricultural University , Zhengzhou , Henan , P. R. China
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200
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Bahmanyar S. Spatial regulation of phospholipid synthesis within the nuclear envelope domain of the endoplasmic reticulum. Nucleus 2015; 6:102-6. [PMID: 25671705 PMCID: PMC4615902 DOI: 10.1080/19491034.2015.1010942] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Revised: 01/15/2015] [Accepted: 01/17/2015] [Indexed: 11/05/2022] Open
Abstract
The endoplasmic reticulum (ER) is an extensive membrane system that serves as a platform for de novo phospholipid synthesis. The ER is partitioned into distinct functional and structural domains, the most notable of which is the nuclear envelope. Here we discuss the role of nuclear envelope localized CNEP-1(Nem1) in spatial regulation of de novo phospholipid synthesis within the ER. CNEP-1(Nem1) is an activator of lipin(Pah1), which is the key phosphatidic acid phosphatase that regulates the metabolic branch-point between the production of phosphatidylinositol (PtdIns) and major membrane phospholipids, phosphatidylcholine (PC) and phosphatidylethanolamine (PE). CNEP-1 activates lipin at the nuclear envelope to bias phospholipid flux toward PC and PE production and to limit PtdIns incorporation. Increased PtdIns causes the formation of ectopic ER sheets in the vicinity of the nucleus that wrap around the nuclear envelope and cause downstream defects in NE disassembly. We propose that spatial regulation of phospholipid flux promotes partitioning of the ER into distinct subdomains by generating a gradient of PtdIns incorporation.
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Affiliation(s)
- Shirin Bahmanyar
- Department of Molecular Cellular and Developmental Biology; Yale University; New Haven, CT USA
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