1
|
Cohen-Or M, Chapnik N, Froy O. β-Hydroxy-β-methylbutyrate (HMB) leads to phospholipase D2 (PLD2) activation and alters circadian rhythms in myotubes. Food Funct 2024; 15:4389-4398. [PMID: 38563085 DOI: 10.1039/d3fo04174c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
β-Hydroxy-β-methylbutyrate (HMB) is a breakdown product of leucine, which promotes muscle growth. Although some studies indicate that HMB activates AKT and mTOR, others show activation of the downstream effectors, P70S6K and S6, independent of mTOR. Our aim was to study the metabolic effect of HMB around the circadian clock in order to determine more accurately the signaling pathway involved. C2C12 myotubes were treated with HMB and clock, metabolic and myogenic markers were measured around the clock. HMB-treated C2C12 myotubes showed no activation of AKT and mTOR, but did show activation of P70S6K and S6. Activation of P70S6K and S6 was also found when myotubes were treated with HMB combined with metformin, an indirect mTOR inhibitor, or rapamycin, a direct mTOR inhibitor. The activation of the P70S6K and S6 independent of AKT and mTOR, was accompanied by increased activation of phospholipase D2 (PLD). In addition, HMB led to high amplitude and advanced circadian rhythms. In conclusion, HMB induces myogenesis in C2C12 by activating P70S6K and S6 via PLD2, rather than AKT and mTOR, leading to high amplitude advanced rhythms.
Collapse
Affiliation(s)
- Meytal Cohen-Or
- Institute of Biochemistry, Food Science and Nutrition, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
| | - Nava Chapnik
- Institute of Biochemistry, Food Science and Nutrition, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
| | - Oren Froy
- Institute of Biochemistry, Food Science and Nutrition, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
| |
Collapse
|
2
|
Tawara W, Morisasa M, Mukai R, Suo R, Itoi S, Mori T, Goto-Inoue N. A lipidomics approach reveals novel phospholipid changes in palmitate-treated C2C12 myotubes. Lipids 2024; 59:55-63. [PMID: 38299442 DOI: 10.1002/lipd.12387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 01/08/2024] [Accepted: 01/09/2024] [Indexed: 02/02/2024]
Abstract
Type 2 diabetes mellitus (T2DM) is a highly prevalent metabolic disorder. Insulin resistance and oxidative stress are associated with T2DM development. The hypothesis that patients with T2DM show excess accumulation of lipids, such as ceramides (Cers) and diacylglycerols (DAGs), in their skeletal muscles has been widely supported; however, detailed lipidomic data at the molecular species level are limited. Therefore, in this study, we aimed to investigate the in vitro dynamics of total lipids, including phospholipids (PLs), sphingolipids, and neutral lipids, in palmitic acid-induced insulin-resistant C2C12 skeletal muscle cells. Our data demonstrated that the profiles of not only Cers and DAGs but also those of PLs showed considerably differences after palmitate treatment. We found that PL synthesis reduced and PL degradation increased after palmitate treatment. These findings may aid in the development of treatments to ameliorate muscle dysfunction caused by lipid accumulation in muscles.
Collapse
Affiliation(s)
- Wakako Tawara
- Department of Marine Sciences, College of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa, Japan
| | - Mizuki Morisasa
- Department of Marine Sciences, College of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa, Japan
| | - Risa Mukai
- Department of Marine Sciences, College of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa, Japan
| | - Rei Suo
- Department of Marine Sciences, College of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa, Japan
| | - Shiro Itoi
- Department of Marine Sciences, College of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa, Japan
| | - Tsukasa Mori
- Department of Marine Sciences, College of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa, Japan
| | - Naoko Goto-Inoue
- Department of Marine Sciences, College of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa, Japan
| |
Collapse
|
3
|
Tei R, Bagde SR, Fromme JC, Baskin JM. Activity-based directed evolution of a membrane editor in mammalian cells. Nat Chem 2023; 15:1030-1039. [PMID: 37217787 PMCID: PMC10525039 DOI: 10.1038/s41557-023-01214-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 04/24/2023] [Indexed: 05/24/2023]
Abstract
Cellular membranes contain numerous lipid species, and efforts to understand the biological functions of individual lipids have been stymied by a lack of approaches for controlled modulation of membrane composition in situ. Here we present a strategy for editing phospholipids, the most abundant lipids in biological membranes. Our membrane editor is based on a bacterial phospholipase D (PLD), which exchanges phospholipid head groups through hydrolysis or transphosphatidylation of phosphatidylcholine with water or exogenous alcohols. Exploiting activity-dependent directed enzyme evolution in mammalian cells, we have developed and structurally characterized a family of 'superPLDs' with up to a 100-fold enhancement in intracellular activity. We demonstrate the utility of superPLDs for both optogenetics-enabled editing of phospholipids within specific organelle membranes in live cells and biocatalytic synthesis of natural and unnatural designer phospholipids in vitro. Beyond the superPLDs, activity-based directed enzyme evolution in mammalian cells is a generalizable approach to engineer additional chemoenzymatic biomolecule editors.
Collapse
Affiliation(s)
- Reika Tei
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
| | - Saket R Bagde
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - J Christopher Fromme
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Jeremy M Baskin
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA.
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA.
| |
Collapse
|
4
|
Archer GS, Sobotik EB. Evaluation of the Timing of Use of Phosphatidic Acid in the Diet on Growth Performance and Breast Meat Yield in Broilers. Animals (Basel) 2022; 12:ani12243446. [PMID: 36552366 PMCID: PMC9774825 DOI: 10.3390/ani12243446] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/05/2022] [Accepted: 12/06/2022] [Indexed: 12/12/2022] Open
Abstract
With a growing increase in further processing of poultry, there has been an increased interest in factors, including feed additives, that may improve broiler performance, increase growth, and influence dressing percentage. Mammalian target of rapamycin (mTOR) is known to play vital roles in protein synthesis; mTOR controls the anabolic and catabolic signaling of skeletal muscle mass, resulting in the modulation of muscle hypertrophy. Exogenous phosphatidic acid (PA) can stimulate the mTOR pathway via its activation of the substrate S6 kinase. A study with 648 Cobb 500 male broilers, housed in 36 floor pens (1.11 m2) from 1 to 42 days of age was conducted to evaluate the timing of PA (Mediator® 50P, Chemi Nutra, Austin, TX, USA) supplementation on the growth performance and carcass yield of broilers. Dietary treatments included T1, Control (CON), T2, 5 mg/bird/day of PA for 42 days (d0−42, PAA); T3, 5 mg/bird/day of PA for 28 days (d15−42, PAGF); and T4, 5 mg/bird/day of PA for 14 days (d29−42, PAF). All birds were weighed on d14, 28, and 42 to obtain BW (body weight), FCR (feed conversion ratio), and MORT (mortality percentage). On d42, eight birds per pen were processed to determine carcass and breast meat yield. No differences were observed in BW at d14 or d28. At d42, birds fed PAA were heavier (3.73 ± 0.02, p < 0.05) than all dietary treatments (3.68 ± 0.02). From d0 to d28, birds fed PAA had the lowest FCR (1.423 ± 0.005, p < 0.05) compared to all dietary treatments (1.441 ± 0.005). From d0 to d42, birds fed PAA and PAGF had a lower FCR (1.545 ± 0.014, p < 0.05) when compared to the CON (1.609 ± 0.013). No differences were observed in MORT between treatments during growout. Increased BW observed in birds fed PAA translated to increased breast fillet weight (0.772 ± 0.009 kg, p < 0.05) when compared to the CON (0.743 ± 0.008 kg). Carcass yields were increased in birds fed PAA (77.48 ± 0.32 kg, p < 0.05) when compared to all dietary treatments (76.24 ± 0.16 kg). Utilizing PA for 42 days increased live weights, improved FCR, increased carcass yield, and increased breast fillet weight at processing. Results from this study indicate that supplementation of PA during all phases of growth may increase the production efficiency of broilers.
Collapse
|
5
|
Jacko D, Schaaf K, Masur L, Windoffer H, Aussieker T, Schiffer T, Zacher J, Bloch W, Gehlert S. Repeated and Interrupted Resistance Exercise Induces the Desensitization and Re-Sensitization of mTOR-Related Signaling in Human Skeletal Muscle Fibers. Int J Mol Sci 2022; 23:ijms23105431. [PMID: 35628242 PMCID: PMC9141560 DOI: 10.3390/ijms23105431] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 05/07/2022] [Accepted: 05/09/2022] [Indexed: 02/06/2023] Open
Abstract
The acute resistance exercise (RE)-induced phosphorylation of mTOR-related signaling proteins in skeletal muscle can be blunted after repeated RE. The time frame in which the phosphorylation (p) of mTORS2448, p70S6kT421/S424, and rpS6S235/236 will be reduced during an RE training period in humans and whether progressive (PR) loading can counteract such a decline has not been described. (1) To enclose the time frame in which pmTORS2448, prpS6S235/236, and pp70S6kT421/S424 are acutely reduced after RE occurs during repeated RE. (2) To test whether PR will prevent that reduction compared to constant loading (CO) and (3) whether 10 days without RE may re-increase blunted signaling. Fourteen healthy males (24 ± 2.8 yrs.; 1.83 ± 0.1 cm; 79.3 ± 8.5 kg) were subjected to RE with either PR (n = 8) or CO (n = 6) loading. Subjects performed RE thrice per week, conducting three sets with 10−12 repetitions on a leg press and leg extension machine. Muscle biopsies were collected at rest (T0), 45 min after the first (T1), seventh (T7), 13th (T13), and 14th (X-T14) RE session. No differences were found between PR and CO for any parameter. Thus, the groups were combined, and the results show the merged values. prpS6S235/236 and pp70s6kT421/S424 were increased at T1, but were already reduced at T7 and up to T13 compared to T1. Ten days without RE re-increased prpS6S235/236 and pp70S6kT421/S424 at X-T14 to a level comparable to that of T1. pmTORS2448 was increased from T1 to X-T14 and did not decline over the training period. Single-fiber immunohistochemistry revealed a reduction in prpS6S235/236 in type I fibers from T1 to T13 and a re-increase at X-T14, which was more augmented in type II fibers at T13 (p < 0.05). The entity of myofibers revealed a high heterogeneity in the level of prpS6S235/236, possibly reflecting individual contraction-induced stress during RE. The type I and II myofiber diameter increased from T0 and T1 to T13 and X-T14 (p < 0.05) prpS6S235/236 and pp70s6kT421/S424 reflect RE-induced states of desensitization and re-sensitization in dependency on frequent loading by RE, but also by its cessation.
Collapse
Affiliation(s)
- Daniel Jacko
- Department of Molecular and Cellular Sports Medicine, Institute of Cardiovascular Research and Sports Medicine, German Sport University Cologne, 50933 Cologne, Germany; (D.J.); (K.S.); (L.M.); (H.W.); (T.A.); (W.B.)
- Olympic Base Center NRW/Rhineland, 50933 Cologne, Germany
| | - Kirill Schaaf
- Department of Molecular and Cellular Sports Medicine, Institute of Cardiovascular Research and Sports Medicine, German Sport University Cologne, 50933 Cologne, Germany; (D.J.); (K.S.); (L.M.); (H.W.); (T.A.); (W.B.)
| | - Lukas Masur
- Department of Molecular and Cellular Sports Medicine, Institute of Cardiovascular Research and Sports Medicine, German Sport University Cologne, 50933 Cologne, Germany; (D.J.); (K.S.); (L.M.); (H.W.); (T.A.); (W.B.)
| | - Hannes Windoffer
- Department of Molecular and Cellular Sports Medicine, Institute of Cardiovascular Research and Sports Medicine, German Sport University Cologne, 50933 Cologne, Germany; (D.J.); (K.S.); (L.M.); (H.W.); (T.A.); (W.B.)
| | - Thorben Aussieker
- Department of Molecular and Cellular Sports Medicine, Institute of Cardiovascular Research and Sports Medicine, German Sport University Cologne, 50933 Cologne, Germany; (D.J.); (K.S.); (L.M.); (H.W.); (T.A.); (W.B.)
| | - Thorsten Schiffer
- Outpatient Clinic for Sports Traumatology and Public Health Consultation, German Sport University Cologne, 50933 Cologne, Germany;
| | - Jonas Zacher
- Department ofPreventative and Rehabilitative Sports and Performance Medicine, Institute of Cardiology and Sports Medicine, German Sports University Cologne, 50933 Cologne, Germany;
| | - Wilhelm Bloch
- Department of Molecular and Cellular Sports Medicine, Institute of Cardiovascular Research and Sports Medicine, German Sport University Cologne, 50933 Cologne, Germany; (D.J.); (K.S.); (L.M.); (H.W.); (T.A.); (W.B.)
- German Research Centre of Elite Sport (Momentum), German Sport University Cologne, 50933 Cologne, Germany
| | - Sebastian Gehlert
- Department of Molecular and Cellular Sports Medicine, Institute of Cardiovascular Research and Sports Medicine, German Sport University Cologne, 50933 Cologne, Germany; (D.J.); (K.S.); (L.M.); (H.W.); (T.A.); (W.B.)
- Institute of Sport Science, Biosciences of Sports, University of Hildesheim, 31141 Hildesheim, Germany
- Correspondence: ; Tel.: +49-(0)-5121-883-580; Fax: +49-(0)-5121-883-591
| |
Collapse
|
6
|
Tei R, Baskin JM. Click chemistry and optogenetic approaches to visualize and manipulate phosphatidic acid signaling. J Biol Chem 2022; 298:101810. [PMID: 35276134 PMCID: PMC9006657 DOI: 10.1016/j.jbc.2022.101810] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 02/12/2022] [Accepted: 02/19/2022] [Indexed: 12/28/2022] Open
Abstract
The simple structure of phosphatidic acid (PA) belies its complex biological functions as both a key phospholipid biosynthetic intermediate and a potent signaling molecule. In the latter role, PA controls processes including vesicle trafficking, actin dynamics, cell growth, and migration. However, experimental methods to decode the pleiotropy of PA are sorely lacking. Because PA metabolism and trafficking are rapid, approaches to accurately visualize and manipulate its levels require high spatiotemporal precision. Here, we describe recent efforts to create a suite of chemical tools that enable imaging and perturbation of PA signaling. First, we describe techniques to visualize PA production by phospholipase D (PLD) enzymes, which are major producers of PA, called Imaging Phospholipase D Activity with Clickable Alcohols via Transphosphatidylation (IMPACT). IMPACT harnesses the ability of endogenous PLD enzymes to accept bioorthogonally tagged alcohols in transphosphatidylation reactions to generate functionalized reporter lipids that are subsequently fluorescently tagged via click chemistry. Second, we describe two light-controlled approaches for precisely manipulating PA signaling. Optogenetic PLDs use light-mediated heterodimerization to recruit a bacterial PLD to desired organelle membranes, and photoswitchable PA analogs contain azobenzene photoswitches in their acyl tails, enabling molecular shape and bioactivity to be controlled by light. We highlight select applications of these tools for studying GPCR–Gq signaling, discovering regulators of PLD signaling, tracking intracellular lipid transport pathways, and elucidating new oncogenic signaling roles for PA. We envision that these chemical tools hold promise for revealing many new insights into lipid signaling pathways.
Collapse
Affiliation(s)
- Reika Tei
- Department of Chemistry and Chemical Biology and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, USA 14853
| | - Jeremy M Baskin
- Department of Chemistry and Chemical Biology and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, USA 14853.
| |
Collapse
|
7
|
p70 S6 kinase as a therapeutic target in cancers: More than just an mTOR effector. Cancer Lett 2022; 535:215593. [PMID: 35176419 DOI: 10.1016/j.canlet.2022.215593] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 01/25/2022] [Accepted: 02/06/2022] [Indexed: 11/23/2022]
Abstract
p70 S6 kinase (p70S6K) is best-known for its regulatory roles in protein synthesis and cell growth by phosphorylating its primary substrate, ribosomal protein S6, upon mitogen stimulation. The enhanced expression/activation of p70S6K has been correlated with poor prognosis in some cancer types, suggesting that it may serve as a biomarker for disease monitoring. p70S6K is a critical downstream effector of the oncogenic PI3K/Akt/mTOR pathway and its activation is tightly regulated by an ordered cascade of Ser/Thr phosphorylation events. Nonetheless, it should be noted that other upstream mechanisms regulating p70S6K at both the post-translational and post-transcriptional levels also exist. Activated p70S6K could promote various aspects of cancer progression such as epithelial-mesenchymal transition, cancer stemness and drug resistance. Importantly, novel evidence showing that p70S6K may also regulate different cellular components in the tumor microenvironment will be discussed. Therapeutic targeting of p70S6K alone or in combination with traditional chemotherapies or other microenvironmental-based drugs such as immunotherapy may represent promising approaches against cancers with aberrant p70S6K signaling. Currently, the only clinically available p70S6K inhibitors are rapamycin analogs (rapalogs) which target mTOR. However, there are emerging p70S6K-selective drugs which are going through active preclinical or clinical trial phases. Moreover, various screening strategies have been used for the discovery of novel p70S6K inhibitors, hence bringing new insights for p70S6K-targeted therapy.
Collapse
|
8
|
Borga C, Businello G, Murgioni S, Bergamo F, Martini C, De Carlo E, Trevellin E, Vettor R, Fassan M. Treatment personalization in gastrointestinal neuroendocrine tumors. Curr Treat Options Oncol 2021; 22:29. [PMID: 33641005 DOI: 10.1007/s11864-021-00825-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/18/2021] [Indexed: 12/12/2022]
Abstract
OPINION STATEMENT The clinical scenario of gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) is continuously changing due to significant improvements in the definition of their molecular landscapes and the introduction of innovative therapeutic approaches. Many efforts are currently employed in the integration of the genetics/epigenetics and clinical information. This is leading to an improvement of tumor classification, prognostic stratification and ameliorating the management of patients based on a personalized approach.
Collapse
Affiliation(s)
- Chiara Borga
- Surgical Pathology Unit, Department of Medicine (DIMED), University of Padua, Padua, Italy
| | - Gianluca Businello
- Surgical Pathology Unit, Department of Medicine (DIMED), University of Padua, Padua, Italy
| | - Sabina Murgioni
- Unit of Medical Oncology 1, Veneto Institute of Oncology IOV-IRCCS, Padua, Italy
| | - Francesca Bergamo
- Unit of Medical Oncology 1, Veneto Institute of Oncology IOV-IRCCS, Padua, Italy
| | - Chiara Martini
- Endocrine-Metabolic Unit, Department of Medicine (DIMED), University of Padua, Padua, Italy
| | - Eugenio De Carlo
- Endocrine-Metabolic Unit, Department of Medicine (DIMED), University of Padua, Padua, Italy
| | - Elisabetta Trevellin
- Endocrine-Metabolic Unit, Department of Medicine (DIMED), University of Padua, Padua, Italy
| | - Roberto Vettor
- Endocrine-Metabolic Unit, Department of Medicine (DIMED), University of Padua, Padua, Italy
| | - Matteo Fassan
- Surgical Pathology Unit, Department of Medicine (DIMED), University of Padua, Padua, Italy.
| |
Collapse
|
9
|
New Era of Diacylglycerol Kinase, Phosphatidic Acid and Phosphatidic Acid-Binding Protein. Int J Mol Sci 2020; 21:ijms21186794. [PMID: 32947951 PMCID: PMC7555651 DOI: 10.3390/ijms21186794] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 09/11/2020] [Accepted: 09/14/2020] [Indexed: 12/12/2022] Open
Abstract
Diacylglycerol kinase (DGK) phosphorylates diacylglycerol (DG) to generate phosphatidic acid (PA). Mammalian DGK consists of ten isozymes (α–κ) and governs a wide range of physiological and pathological events, including immune responses, neuronal networking, bipolar disorder, obsessive-compulsive disorder, fragile X syndrome, cancer, and type 2 diabetes. DG and PA comprise diverse molecular species that have different acyl chains at the sn-1 and sn-2 positions. Because the DGK activity is essential for phosphatidylinositol turnover, which exclusively produces 1-stearoyl-2-arachidonoyl-DG, it has been generally thought that all DGK isozymes utilize the DG species derived from the turnover. However, it was recently revealed that DGK isozymes, except for DGKε, phosphorylate diverse DG species, which are not derived from phosphatidylinositol turnover. In addition, various PA-binding proteins (PABPs), which have different selectivities for PA species, were recently found. These results suggest that DGK–PA–PABP axes can potentially construct a large and complex signaling network and play physiologically and pathologically important roles in addition to DGK-dependent attenuation of DG–DG-binding protein axes. For example, 1-stearoyl-2-docosahexaenoyl-PA produced by DGKδ interacts with and activates Praja-1, the E3 ubiquitin ligase acting on the serotonin transporter, which is a target of drugs for obsessive-compulsive and major depressive disorders, in the brain. This article reviews recent research progress on PA species produced by DGK isozymes, the selective binding of PABPs to PA species and a phosphatidylinositol turnover-independent DG supply pathway.
Collapse
|
10
|
Skeletal muscle hypertrophy: molecular and applied aspects of exercise physiology. GERMAN JOURNAL OF EXERCISE AND SPORT RESEARCH 2020. [DOI: 10.1007/s12662-020-00652-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
11
|
Yao Y, Wang X, Li H, Fan J, Qian X, Li H, Xu Y. Phospholipase D as a key modulator of cancer progression. Biol Rev Camb Philos Soc 2020; 95:911-935. [PMID: 32073216 DOI: 10.1111/brv.12592] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 02/01/2020] [Accepted: 02/06/2020] [Indexed: 12/15/2022]
Abstract
The phospholipase D (PLD) family has a ubiquitous expression in cells. PLD isoforms (PLDs) and their hydrolysate phosphatidic acid (PA) have been demonstrated to engage in multiple stages of cancer progression. Aberrant expression of PLDs, especially PLD1 and PLD2, has been detected in various cancers. Inhibition or elimination of PLDs activity has been shown to reduce tumour growth and metastasis. PLDs and PA also serve as downstream effectors of various cell-surface receptors, to trigger and regulate propagation of intracellular signals in the process of tumourigenesis and metastasis. Here, we discuss recent advances in understanding the functions of PLDs and PA in discrete stages of cancer progression, including cancer cell growth, invasion and migration, and angiogenesis, with special emphasis on the tumour-associated signalling pathways mediated by PLDs and PA and the functional importance of PLDs and PA in cancer therapy.
Collapse
Affiliation(s)
- Yuanfa Yao
- Department of Biomedical Engineering, Key Laboratory of Biomedical Engineering of Ministry of Education, Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, China.,Department of Endocrinology, The Affiliated Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Xinyi Wang
- Department of Biomedical Engineering, Key Laboratory of Biomedical Engineering of Ministry of Education, Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, China.,Department of Clinical Medicine, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Hanbing Li
- Institute of Pharmacology, College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, China
| | - Jiannan Fan
- Department of Biomedical Engineering, Key Laboratory of Biomedical Engineering of Ministry of Education, Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, China
| | - Xiaohan Qian
- Department of Biomedical Engineering, Key Laboratory of Biomedical Engineering of Ministry of Education, Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, China.,Department of Respiratory Disease, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Hong Li
- Department of Endocrinology, The Affiliated Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yingke Xu
- Department of Biomedical Engineering, Key Laboratory of Biomedical Engineering of Ministry of Education, Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, China.,Department of Endocrinology, The Affiliated Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| |
Collapse
|
12
|
McDermott MI, Wang Y, Wakelam MJO, Bankaitis VA. Mammalian phospholipase D: Function, and therapeutics. Prog Lipid Res 2019; 78:101018. [PMID: 31830503 DOI: 10.1016/j.plipres.2019.101018] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 10/08/2019] [Accepted: 10/14/2019] [Indexed: 01/23/2023]
Abstract
Despite being discovered over 60 years ago, the precise role of phospholipase D (PLD) is still being elucidated. PLD enzymes catalyze the hydrolysis of the phosphodiester bond of glycerophospholipids producing phosphatidic acid and the free headgroup. PLD family members are found in organisms ranging from viruses, and bacteria to plants, and mammals. They display a range of substrate specificities, are regulated by a diverse range of molecules, and have been implicated in a broad range of cellular processes including receptor signaling, cytoskeletal regulation and membrane trafficking. Recent technological advances including: the development of PLD knockout mice, isoform-specific antibodies, and specific inhibitors are finally permitting a thorough analysis of the in vivo role of mammalian PLDs. These studies are facilitating increased recognition of PLD's role in disease states including cancers and Alzheimer's disease, offering potential as a target for therapeutic intervention.
Collapse
Affiliation(s)
- M I McDermott
- Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77843-1114, United States of America.
| | - Y Wang
- Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77843-1114, United States of America; Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128, United States of America
| | - M J O Wakelam
- Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, United Kingdom
| | - V A Bankaitis
- Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77843-1114, United States of America; Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128, United States of America; Department of Chemistry, Texas A&M University, College Station, Texas 77840, United States of America
| |
Collapse
|
13
|
Valladares-Ide D, Peñailillo L, Collao N, Marambio H, Deldicque L, Zbinden-Foncea H. Activation of protein synthesis, regeneration, and MAPK signaling pathways following repeated bouts of eccentric cycling. Am J Physiol Endocrinol Metab 2019; 317:E1131-E1139. [PMID: 31593504 DOI: 10.1152/ajpendo.00216.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The aim of this study was to examine the activation of skeletal muscle signaling pathways related to protein synthesis and the gene expression of regeneration/degradation markers following repeated bouts of eccentric cycling. Nine untrained men (25.4 ± 1.9 yr) performed two 30-min eccentric cycling bouts (ECC1, ECC2) at 85% of maximal concentric workload, separated by 2 wk. Muscle biopsies were taken from the vastus lateralis before and 2 h after each bout. Indirect markers of muscle damage were assessed before and 24-48 h after exercise. Changes in the Akt/mammalian target of rapamycin (mTOR)/rbosomal protein S6 kinase 1 (S6K1)/ribosomal protein S6 (rpS6) and MAPK signaling pathways were measured by Western blot and changes in mRNA expression of IL-6 and IL-1β, and myogenic regulatory factors (MRFs) were measured by real-time PCR. ECC1 induced greater increases in indirect markers of muscle damage compared with ECC2. Phosphorylation of S6K1 and rpS6 increased after both exercise bouts (P < 0.05), whereas phosphorylation of mTOR increased after ECC2 only (P = 0.03). Atrogin-1 mRNA expression decreased after ECC1 and ECC2 (P < 0.05) without changes in muscle RING-finger protein-1 mRNA. Basal mRNA levels of myoblast determination protein-1 (MyoD), MRF4, and myogenin were higher 2 wk after ECC1 (P < 0.05). MRF4 mRNA increased after ECC1 and ECC2 (P < 0.05), whereas MyoD mRNA expression increased only after ECC1 (P = 0.03). Phosphorylation of JNK and p38 MAPK increased after both exercise bouts (P < 0.05), similar to IL-6 and IL-1β mRNA expression. All together, these results suggest that differential regulation of the mTOR pathway and MRF expression could mediate the repeated bout effect observed between an initial and secondary bout of eccentric exercise.
Collapse
Affiliation(s)
- Denisse Valladares-Ide
- Exercise Science Laboratory, School of Kinesiology, Faculty of Medicine, Universidad Finis Terrae, Santiago, Chile
| | - Luis Peñailillo
- Exercise Science Laboratory, School of Kinesiology, Faculty of Medicine, Universidad Finis Terrae, Santiago, Chile
| | - Nicolás Collao
- Exercise Science Laboratory, School of Kinesiology, Faculty of Medicine, Universidad Finis Terrae, Santiago, Chile
| | - Hugo Marambio
- Centro de Salud Deportiva, Clínica Santa María, Santiago, Chile
| | - Louise Deldicque
- Institute of Neuroscience, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Hermann Zbinden-Foncea
- Exercise Science Laboratory, School of Kinesiology, Faculty of Medicine, Universidad Finis Terrae, Santiago, Chile
- Centro de Salud Deportiva, Clínica Santa María, Santiago, Chile
| |
Collapse
|
14
|
Noble AR, Hogg K, Suman R, Berney DM, Bourgoin S, Maitland NJ, Rumsby MG. Phospholipase D2 in prostate cancer: protein expression changes with Gleason score. Br J Cancer 2019; 121:1016-1026. [PMID: 31673104 PMCID: PMC6964697 DOI: 10.1038/s41416-019-0610-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 09/20/2019] [Accepted: 10/01/2019] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Phospholipases D1 and D2 (PLD1/2) are implicated in tumorigenesis through their generation of the signalling lipid phosphatidic acid and its downstream effects. Inhibition of PLD1 blocks prostate cell growth and colony formation. Here a role for PLD2 in prostate cancer (PCa), the major cancer of men in the western world, is examined. METHODS PLD2 expression was analysed by immunohistochemistry and western blotting. The effects of PLD2 inhibition on PCa cell viability and cell motility were measured using MTS, colony forming and wound-healing assays. RESULTS PLD2 protein is expressed about equally in luminal and basal prostate epithelial cells. In cells from different Gleason-scored PCa tissue PLD2 protein expression is generally higher than in non-tumorigenic cells and increases in PCa tissue scored Gleason 6-8. PLD2 protein is detected in the cytosol and nucleus and had a punctate appearance. In BPH tissue stromal cells as well as basal and luminal cells express PLD2. PLD2 protein co-expresses with chromogranin A in castrate-resistant PCa tissue. PLD2 inhibition reduces PCa cell viability, colony forming ability and directional cell movement. CONCLUSIONS PLD2 expression correlates with increasing Gleason score to GS8. PLD2 inhibition has the potential to reduce PCa progression.
Collapse
Affiliation(s)
- Amanda R Noble
- Cancer Research Unit, Department of Biology, University of York, York, YO10 5DD, UK
| | - Karen Hogg
- Technology Facility, Department of Biology, University of York, York, YO10 5DD, UK
| | - Rakesh Suman
- Cancer Research Unit, Department of Biology, University of York, York, YO10 5DD, UK
| | - Daniel M Berney
- Department of Molecular Oncology, Barts Cancer Institute, Queen Mary University of London, London, EC1M 6BQ, UK
| | - Sylvain Bourgoin
- Centre de Recherche du CHU de Québec, Axe des Maladies Infectieuses et Immunitaires, local T1-58, 2705 boulevard Laurier, Québec, G1V 4G2, QC, Canada
| | - Norman J Maitland
- Cancer Research Unit, Department of Biology, University of York, York, YO10 5DD, UK
| | - Martin G Rumsby
- Cancer Research Unit, Department of Biology, University of York, York, YO10 5DD, UK.
| |
Collapse
|
15
|
Mao R, Liu H, Yi B, Purohit S, Kuczma M, Kraj P, She JX. Cell-based high throughput screening identified a novel compound that promotes regulatory T cells and prevents autoimmune colitis. Biochem Pharmacol 2019; 169:113618. [PMID: 31449782 DOI: 10.1016/j.bcp.2019.08.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 08/21/2019] [Indexed: 10/26/2022]
Abstract
Regulatory T cells (TR) show great promise for treating autoimmune diseases, allergies and preventing transplant rejection; however, their clinical application has been hampered by the lack of efficient ex vivo or in vivo expansion strategies. Here we report screening data on 130,000 low molecular weight (LMW) compounds for their TR promoting potential using a self-developed high-throughput cell-based assay. One of the lead compounds, an isoxazolecarboxamide designated as TRP38, efficiently converts naïve CD4+ T cells to TR cells in vitro and protects mice from autoimmune colitis in vivo. In addition, TRP38 can synergize with other compounds and/or cytokines such as rapamycin and TGFβ for TR conversion, probably via directly inhibiting P70s6 phosphorylation without affecting mTOR expression, underscoring the importance of complementary and coordinated activity of multiple signaling pathways for the increased level of stable TR cell production.
Collapse
Affiliation(s)
- Rui Mao
- Center for Biotechnology and Genomic Medicine, Augusta University, Augusta, GA 30912, United States
| | - Haitao Liu
- Center for Biotechnology and Genomic Medicine, Augusta University, Augusta, GA 30912, United States
| | - Bing Yi
- Center for Biotechnology and Genomic Medicine, Augusta University, Augusta, GA 30912, United States
| | - Sharad Purohit
- Center for Biotechnology and Genomic Medicine, Augusta University, Augusta, GA 30912, United States; Department of Obstetrics and Gynecology, Medical College of Georgia, Augusta University, Augusta, GA 30912, United States; Department of Interdisciplinary Health Sciences, Augusta University, Augusta, GA 30912, United States
| | - Michal Kuczma
- Center for Biotechnology and Genomic Medicine, Augusta University, Augusta, GA 30912, United States
| | - Piotr Kraj
- Center for Biotechnology and Genomic Medicine, Augusta University, Augusta, GA 30912, United States
| | - Jin-Xiong She
- Center for Biotechnology and Genomic Medicine, Augusta University, Augusta, GA 30912, United States; Department of Obstetrics and Gynecology, Medical College of Georgia, Augusta University, Augusta, GA 30912, United States.
| |
Collapse
|
16
|
Pellegrini C, Columbaro M, Schena E, Prencipe S, Andrenacci D, Iozzo P, Angela Guzzardi M, Capanni C, Mattioli E, Loi M, Araujo-Vilar D, Squarzoni S, Cinti S, Morselli P, Giorgetti A, Zanotti L, Gambineri A, Lattanzi G. Altered adipocyte differentiation and unbalanced autophagy in type 2 Familial Partial Lipodystrophy: an in vitro and in vivo study of adipose tissue browning. Exp Mol Med 2019; 51:1-17. [PMID: 31375660 PMCID: PMC6802660 DOI: 10.1038/s12276-019-0289-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 04/04/2019] [Accepted: 04/16/2019] [Indexed: 01/29/2023] Open
Abstract
Type-2 Familial Partial Lipodystrophy is caused by LMNA mutations. Patients gradually lose subcutaneous fat from the limbs, while they accumulate adipose tissue in the face and neck. Several studies have demonstrated that autophagy is involved in the regulation of adipocyte differentiation and the maintenance of the balance between white and brown adipose tissue. We identified deregulation of autophagy in laminopathic preadipocytes before induction of differentiation. Moreover, in differentiating white adipocyte precursors, we observed impairment of large lipid droplet formation, altered regulation of adipose tissue genes, and expression of the brown adipose tissue marker UCP1. Conversely, in lipodystrophic brown adipocyte precursors induced to differentiate, we noticed activation of autophagy, formation of enlarged lipid droplets typical of white adipocytes, and dysregulation of brown adipose tissue genes. In agreement with these in vitro results indicating conversion of FPLD2 brown preadipocytes toward the white lineage, adipose tissue from FPLD2 patient neck, an area of brown adipogenesis, showed a white phenotype reminiscent of its brown origin. Moreover, in vivo morpho-functional evaluation of fat depots in the neck area of three FPLD2 patients by PET/CT analysis with cold stimulation showed the absence of brown adipose tissue activity. These findings highlight a new pathogenetic mechanism leading to improper fat distribution in lamin A-linked lipodystrophies and show that both impaired white adipocyte turnover and failure of adipose tissue browning contribute to disease. An abnormal distribution of fatty tissues associated with certain tissue disorders is driven by disrupted fat cell differentiation. Type 2 familial partial lipodystrophy (FPLD2) is a genetic condition that results in fat being lost from the limbs and accumulating in the face and neck. Giovanna Lattanzi at the National Research Council of Italy in Bologna and co-workers found that fat cell (adipocyte) precursors did not clearly differentiate into either of the two main fatty tissue types, brown or white, in FPLD2 patients. White adipocyte precursors exhibited impaired lipid formation and abnormal levels of brown tissue markers. Conversely, brown adipocyte precursors showed high lipid levels and increased autophagy, a natural process involving degradation and recycling of cellular components. The neck is normally where brown fat accumulates, but FPLD2 patients had adipocytes there displaying white fat characteristics.
Collapse
Affiliation(s)
- Camilla Pellegrini
- CNR - National Research Council of Italy, Institute of Molecular Genetics "Luigi Luca Cavalli-Sforza", Unit of Bologna, Bologna, Italy
| | | | - Elisa Schena
- CNR - National Research Council of Italy, Institute of Molecular Genetics "Luigi Luca Cavalli-Sforza", Unit of Bologna, Bologna, Italy.,IRCCS, Istituto Ortopedico Rizzoli, Bologna, Italy
| | - Sabino Prencipe
- CNR - National Research Council of Italy, Institute of Molecular Genetics "Luigi Luca Cavalli-Sforza", Unit of Bologna, Bologna, Italy
| | - Davide Andrenacci
- CNR - National Research Council of Italy, Institute of Molecular Genetics "Luigi Luca Cavalli-Sforza", Unit of Bologna, Bologna, Italy.,IRCCS, Istituto Ortopedico Rizzoli, Bologna, Italy
| | - Patricia Iozzo
- CNR - National Research Council of Italy, Institute of Clinical Physiology, Pisa, Italy
| | - Maria Angela Guzzardi
- CNR - National Research Council of Italy, Institute of Clinical Physiology, Pisa, Italy
| | - Cristina Capanni
- CNR - National Research Council of Italy, Institute of Molecular Genetics "Luigi Luca Cavalli-Sforza", Unit of Bologna, Bologna, Italy.,IRCCS, Istituto Ortopedico Rizzoli, Bologna, Italy
| | - Elisabetta Mattioli
- CNR - National Research Council of Italy, Institute of Molecular Genetics "Luigi Luca Cavalli-Sforza", Unit of Bologna, Bologna, Italy.,IRCCS, Istituto Ortopedico Rizzoli, Bologna, Italy
| | - Manuela Loi
- CNR - National Research Council of Italy, Institute of Molecular Genetics "Luigi Luca Cavalli-Sforza", Unit of Bologna, Bologna, Italy
| | - David Araujo-Vilar
- Department of Medicine, CIMUS Biomedical Research Institute, University of Santiago de Compostela, Santiago de Compostela, Spain
| | - Stefano Squarzoni
- CNR - National Research Council of Italy, Institute of Molecular Genetics "Luigi Luca Cavalli-Sforza", Unit of Bologna, Bologna, Italy.,IRCCS, Istituto Ortopedico Rizzoli, Bologna, Italy
| | - Saverio Cinti
- Department of Experimental and Clinical Medicine, University of Ancona (UniversitàPolitecnicadelle Marche), Ancona, Italy.,Center of Obesity of University of Ancona, Ancona, Italy
| | - Paolo Morselli
- Plastic Surgery Unit, Department of Specialised, Experimental, and Diagnostic Medicine, Alma Mater Studiorum University of Bologna, S Orsola-Malpighi Hospital, Bologna, Italy
| | | | - Laura Zanotti
- Endocrinology Unit, Department of Medical and Surgical Sciences, Alma Mater Studiorum University of Bologna, S Orsola-Malpighi Hospital, Bologna, Italy
| | - Alessandra Gambineri
- Endocrinology Unit, Department of Medical and Surgical Sciences, Alma Mater Studiorum University of Bologna, S Orsola-Malpighi Hospital, Bologna, Italy
| | - Giovanna Lattanzi
- CNR - National Research Council of Italy, Institute of Molecular Genetics "Luigi Luca Cavalli-Sforza", Unit of Bologna, Bologna, Italy. .,IRCCS, Istituto Ortopedico Rizzoli, Bologna, Italy.
| |
Collapse
|
17
|
Das F, Maity S, Ghosh-Choudhury N, Kasinath BS, Ghosh Choudhury G. Deacetylation of S6 kinase promotes high glucose-induced glomerular mesangial cell hypertrophy and matrix protein accumulation. J Biol Chem 2019; 294:9440-9460. [PMID: 31028173 DOI: 10.1074/jbc.ra118.007023] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 04/09/2019] [Indexed: 12/30/2022] Open
Abstract
S6 kinase acts as a driver for renal hypertrophy and matrix accumulation, two key pathologic signatures of diabetic nephropathy. As a post-translational modification, S6 kinase undergoes acetylation at the C terminus. The role of this acetylation to regulate kidney glomerular cell hypertrophy and matrix expansion is not known. In mesangial cells, high glucose decreased the acetylation and enhanced phosphorylation of S6 kinase and its substrates rps6 and eEF2 kinase that lead to dephosphorylation of eEF2. To determine the mechanism of S6 kinase deacetylation, we found that trichostatin A, a pan-histone deacetylase (HDAC) inhibitor, blocked all high glucose-induced effects. Furthermore, high glucose increased the expression and association of HDAC1 with S6 kinase. HDAC1 decreased the acetylation of S6 kinase and mimicked the effects of high glucose, resulting in mesangial cell hypertrophy and expression of fibronectin and collagen I (α2). In contrast, siRNA against HDAC1 inhibited these effects by high glucose. A C-terminal acetylation-mimetic mutant of S6 kinase suppressed high glucose-stimulated phosphorylation of S6 kinase, rps6 and eEF2 kinase, and inhibited the dephosphorylation of eEF2. Also, the acetylation mimetic attenuated the mesangial cell hypertrophy and fibronectin and collagen I (α2) expression. Conversely, an S6 kinase acetylation-deficient mutant induced all the above effects of high glucose. Finally, in the renal glomeruli of diabetic rats, the acetylation of S6 kinase was significantly reduced concomitant with increased HDAC1 and S6 kinase activity. In aggregate, our data uncovered a previously unrecognized role of S6 kinase deacetylation in high glucose-induced mesangial cell hypertrophy and matrix protein expression.
Collapse
Affiliation(s)
| | | | | | | | - Goutam Ghosh Choudhury
- Departments of Medicine and .,Departments of Medicine and.,Geriatric Research, Education and Clinical Center, South Texas Veterans Health Care System, San Antonio, Texas 78229 and
| |
Collapse
|
18
|
Bermúdez V, Tenconi PE, Giusto NM, Mateos MV. Lipopolysaccharide-Induced Autophagy Mediates Retinal Pigment Epithelium Cells Survival. Modulation by the Phospholipase D Pathway. Front Cell Neurosci 2019; 13:154. [PMID: 31327962 PMCID: PMC6497095 DOI: 10.3389/fncel.2019.00154] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 04/08/2019] [Indexed: 12/12/2022] Open
Abstract
Inflammation and oxidative stress are common factors involved in the pathogenesis of retinal diseases, such as aged-related macular degeneration (AMD) and diabetic retinopathy (DR). Autophagy is a catabolic process essential to cell survival in response to stress. This process is highly active in retinal pigment epithelium (RPE) cells. Our previous findings demonstrated that lipopolysaccharide (LPS) induces an inflammatory response of RPE cells that implies classical phospholipases D (PLD1 and 2) activation, cyclooxygenase-2 (COX-2) expression, prostaglandin E2 (PGE2) production and reduced cell viability. In this work, we studied the autophagic process and its modulation by the PLD pathway in D407 and ARPE-19 RPE cells exposed to LPS. LPS (10 μg/ml or 25 μg/ml) exposure for 24 h increased light chain 3B-II (LC3B-II) content (an autophagy marker) and LC3B-positive punctate structures in both RPE cell lines studied. Next, the drug bafilomycin A1 (BAF, 50 nM) was used to block the autophagic flux. In cells pre-incubated with BAF, LC3B-II and sequestosome 1 (SQSTM1/p62) levels and autophagosome-like structures were increased by LPS, demonstrating that the inflammatory injury increases the autophagic process in RPE cells. To study the role of the PLD pathway, cells were pre-incubated for 1 h with selective PLD1 (VU0359595) or PLD2 (VU0285655-1) inhibitors prior to LPS addition. Under control condition, LC3B-positive punctate structures were increased in cells pre-incubated with PLD2 inhibitor while with PLD1 inhibitor were increased in cells exposed to LPS. MTT reduction assays showed that early autophagy inhibitors, 3-methyladenin (3-MA) or LY294002, enhanced the loss in cell viability induced by LPS exposure for 48 h. On the contrary, the inhibition of PLD1 and PLD2 prevented the loss in cell viability induced by LPS. In conclusion, our results show that even though LPS treatment promotes an inflammatory response in RPE cells, it also triggers the activation of the autophagic process which in turn may serve as a protective mechanism for the cells. In addition, we demonstrate that the PLD pathway modulates the autophagic process in RPE cells. Our findings contribute to the knowledge of the molecular basis of retinal inflammatory and degenerative diseases and open new avenues for potential therapeutic exploration.
Collapse
Affiliation(s)
- Vicente Bermúdez
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina.,Departamento de Biología, Bioquímica y Farmacia (DBByF), Universidad Nacional del Sur (UNS), Bahía Blanca, Argentina
| | - Paula Estefanía Tenconi
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina.,Departamento de Biología, Bioquímica y Farmacia (DBByF), Universidad Nacional del Sur (UNS), Bahía Blanca, Argentina
| | - Norma María Giusto
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina.,Departamento de Biología, Bioquímica y Farmacia (DBByF), Universidad Nacional del Sur (UNS), Bahía Blanca, Argentina
| | - Melina Valeria Mateos
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina.,Departamento de Biología, Bioquímica y Farmacia (DBByF), Universidad Nacional del Sur (UNS), Bahía Blanca, Argentina
| |
Collapse
|
19
|
Behringer M, Willberg C. Application of Blood Flow Restriction to Optimize Exercise Countermeasures for Human Space Flight. Front Physiol 2019; 10:33. [PMID: 30740059 PMCID: PMC6355682 DOI: 10.3389/fphys.2019.00033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 01/11/2019] [Indexed: 11/13/2022] Open
Abstract
In recent years there has been a strong increase in publications on blood flow restriction (BFR) training. In particular, the fact that this type of training requires only low resistance to induce muscle strength and mass gains, makes BFR training interesting for athletes and scientists alike. For the same reason this type of training is particularly interesting for astronauts working out in space. Lower resistance during training would have the advantage of reducing the risk of strain-induced injuries. Furthermore, strength training with lower resistances would have implications for the equipment required for training under microgravity conditions, as significantly lower resistances have to be provided by the training machines. Even though we are only about to understand the effects of blood flow restriction on exercise types other than low-intensity strength training, the available data indicate that BFR of leg muscles is also able to improve the training effects of walking or running at slow speeds. The underlying mechanisms of BFR-induced functional and structural adaptations are still unclear. An essential aspect seems to be the premature fatigue of Type-I muscle fibers, which requires premature recruitment of Type-II muscle fibers to maintain a given force output. Other theories assume that cell swelling, anabolic hormones, myokines and reactive oxygen species are involved in the mediation of BFR training-related effects. This review article is intended to summarize the main advantages and disadvantages, but also the potential risks of such training for astronauts.
Collapse
Affiliation(s)
- Michael Behringer
- Institute of Sports Sciences, Goethe University Frankfurt, Frankfurt, Germany
| | - Christina Willberg
- Institute of Sports Sciences, Goethe University Frankfurt, Frankfurt, Germany
| |
Collapse
|
20
|
Abstract
Extracellular vesicles (EVs), and exosomes in particular, were initially considered as "garbage bags" for secretion of undesired cellular components. This view has changed considerably over the last two decades, and exosomes have now emerged as important organelles controlling cell-to-cell signaling. They are present in biological fluids and have important roles in the communication between cells in physiological and pathological processes. They are envisioned for clinical use as carriers of biomarkers, therapeutic targets, and vehicles for drug delivery. Important efforts are being made to characterize the contents of these vesicles and to understand the mechanisms that govern their biogenesis and modes of action. This chapter aims to recapitulate the place given to lipids in our understanding of exosome biology. Besides their structural role and their function as carriers, certain lipids and lipid-modifying enzymes seem to exert privileged functions in this mode of cellular communication. By extension, the use of selective "lipid inhibitors" might turn out to be interesting modulators of exosomal-based cell signaling.
Collapse
Affiliation(s)
- Antonio Luis Egea-Jimenez
- Centre de Recherche en Cancérologie de Marseille, Equipe labellisée Ligue 2018, Aix-Marseille Université, Inserm, CNRS, Institut Paoli Calmettes, Marseille, France.,Department of Human Genetics, K. U. Leuven, Leuven, Belgium
| | - Pascale Zimmermann
- Centre de Recherche en Cancérologie de Marseille, Equipe labellisée Ligue 2018, Aix-Marseille Université, Inserm, CNRS, Institut Paoli Calmettes, Marseille, France. .,Department of Human Genetics, K. U. Leuven, Leuven, Belgium.
| |
Collapse
|
21
|
Sobotik EB, Lee JT, Hagerman S, Archer GS. Evaluation of the Use of Phosphatidic Acid in the Diet on Growth Performance and Breast Meat Yield in Broilers. Animals (Basel) 2018; 8:ani8060087. [PMID: 29874850 PMCID: PMC6025125 DOI: 10.3390/ani8060087] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 05/23/2018] [Accepted: 05/29/2018] [Indexed: 12/17/2022] Open
Abstract
Simple Summary Improving feed conversion while increasing growth is a goal of any broiler nutrition program. The use of feed additives to obtain this goal has increased in recent years. However, increased growth in broilers has resulted in meat quality issues such as woody breast and white striping. In humans, utilizing phosphatidic acid (PA) in the diet has demonstrated increased lean muscle formation. If PA could be used in poultry, it may allow for increased growth without the pitfalls of poor meat quality. Abstract The use of feed additives to improve feed conversion while increasing growth is the goal of any broiler nutrition program. Therefore, it is important to evaluate potential feed additives not only for increased performance, but also for any negative attributes. A study was conducted to evaluate the effects of feeding phosphatidic acid (PA) to broiler chickens. Two experiments were conducted using exercise in conjunction with PA (Experiment 1(E1)) and administering PA at different inclusion rates in the diet (Experiment 2 (E2)); LowPA (5 mg/bird/day), MidPA (10 mg/bird/day), HighPA (15 mg/bird/day), and control (CON). All birds were weighed bi-weekly during the experiments to obtain average pen weights and feed conversion ratios (FCRs). At the end of the experiments, eight birds per pen were processed to evaluate carcass traits and breast yield. In E1, exercise did not affect growth, feed conversion or processing traits (p > 0.05). However, PA supplementation did increase growth, carcass and breast weight, and carcass and breast yields (p < 0.05). In E2, differences (p < 0.05) in live bird weights between the control birds (1.65 kg) and all PA treatments (pooled mean: 1.73 kg) began at 28 days; however, only the LowPA carried that effect (p = 0.05) through to the conclusion of the trial (3.55 vs. 3.81 kg). Overall, LowPA (1.64) and MidPA (1.69) had lower (p < 0.05) FCRs than the CON treatment (1.74). Increased growth observed in live bird weights in the LowPA translated to increased (p < 0.05) overall carcass weights (2.78 vs. 2.99 kg) and specifically breast filet weights (0.69 vs. 0.76 kg). Yields did not differ (p > 0.05), but with the increased weight feeding LowPA resulted in more total breast meat. Phosphatidic acid did not affect (p > 0.05) woody breast or white striping. In conclusion, dietary PA improved FCR, increased live bird weights, and increased breast fillet weight without increased incidence of white striping. These results indicate that feeding PA may increase production efficiency in broilers.
Collapse
Affiliation(s)
- Eric B Sobotik
- Department of Poultry Science, Texas A&M University-College Station, TX 77843, USA.
| | - Jason T Lee
- Department of Poultry Science, Texas A&M University-College Station, TX 77843, USA.
| | | | - Gregory S Archer
- Department of Poultry Science, Texas A&M University-College Station, TX 77843, USA.
| |
Collapse
|
22
|
Egea-Jimenez AL, Zimmermann P. Phospholipase D and phosphatidic acid in the biogenesis and cargo loading of extracellular vesicles. J Lipid Res 2018; 59:1554-1560. [PMID: 29853529 DOI: 10.1194/jlr.r083964] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 05/09/2018] [Indexed: 12/30/2022] Open
Abstract
Extracellular vesicles released by viable cells (exosomes and microvesicles) have emerged as important organelles supporting cell-cell communication. Because of their potential therapeutic significance, important efforts are being made toward characterizing the contents of these vesicles and the mechanisms that govern their biogenesis. It has been recently demonstrated that the lipid modifying enzyme, phospholipase D (PLD)2, is involved in exosome production and acts downstream of the small GTPase, ARF6. This review aims to recapitulate our current knowledge of the role of PLD2 and its product, phosphatidic acid, in the biogenesis of exosomes and to propose hypotheses for further investigation of a possible central role of these molecules in the biology of these organelles.
Collapse
Affiliation(s)
- Antonio Luis Egea-Jimenez
- Centre de Recherche en Cancérologie de Marseille (CRCM), Equipe labellisée LIGUE 2018, Aix-Marseille Université, Marseille F-13284, France and Inserm U1068, Institut Paoli-Calmettes, and CNRS UMR7258, Marseille F-13009, France
| | - Pascale Zimmermann
- Centre de Recherche en Cancérologie de Marseille (CRCM), Equipe labellisée LIGUE 2018, Aix-Marseille Université, Marseille F-13284, France and Inserm U1068, Institut Paoli-Calmettes, and CNRS UMR7258, Marseille F-13009, France; Department of Human Genetics, University of Leuven, B-3000 Leuven, Belgium.
| |
Collapse
|
23
|
Miller TE, Gomez-Cambronero J. A feedback mechanism between PLD and deadenylase PARN for the shortening of eukaryotic poly(A) mRNA tails that is deregulated in cancer cells. Biol Open 2017; 6:176-186. [PMID: 28011629 PMCID: PMC5312095 DOI: 10.1242/bio.021261] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The removal of mRNA transcript poly(A) tails by 3′→5′ exonucleases is the rate-limiting step in mRNA decay in eukaryotes. Known cellular deadenylases are the CCR4-NOT and PAN complexes, and poly(A)-specific ribonuclease (PARN). The physiological roles and regulation for PARN is beginning to be elucidated. Since phospholipase D (PLD2 isoform) gene expression is upregulated in breast cancer cells and PARN is downregulated, we examined whether a signaling connection existed between these two enzymes. Silencing PARN with siRNA led to an increase in PLD2 protein, whereas overexpression of PARN had the opposite effect. Overexpression of PLD2, however, led to an increase in PARN expression. Thus, PARN downregulates PLD2 whereas PLD2 upregulates PARN. Co-expression of both PARN and PLD2 mimicked this pattern in non-cancerous cells (COS-7 fibroblasts) but, surprisingly, not in breast cancer MCF-7 cells, where PARN switches from inhibition to activation of PLD2 gene and protein expression. Between 30 and 300 nM phosphatidic acid (PA), the product of PLD enzymatic reaction, added exogenously to culture cells had a stabilizing role of both PARN and PLD2 mRNA decay. Lastly, by immunofluorescence microscopy, we observed an intracellular co-localization of PA-loaded vesicles (0.1-1 nm) and PARN. In summary, we report for the first time the involvement of a phospholipase (PLD2) and PA in mediating PARN-induced eukaryotic mRNA decay and the crosstalk between the two enzymes that is deregulated in breast cancer cells. Summary: Cell signaling enzyme phospholipase D2 (PLD2) and its reaction product, phospholipid phosphatidic acid (PA), are involved in mediating PARN-induced eukaryotic mRNA decay.
Collapse
Affiliation(s)
- Taylor E Miller
- Department of Biochemistry and Molecular Biology, Wright State University School of Medicine, Dayton, OH 45435, USA
| | - Julian Gomez-Cambronero
- Center for Experimental Therapeutics and Reperfusion Injury, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA .,Department of Biochemistry and Molecular Biology, Wright State University School of Medicine, Dayton, OH 45435, USA
| |
Collapse
|
24
|
Crowell KT, Steiner JL, Coleman CS, Lang CH. Decreased Whole-Body Fat Mass Produced by Chronic Alcohol Consumption is Associated with Activation of S6K1-Mediated Protein Synthesis and Increased Autophagy in Epididymal White Adipose Tissue. Alcohol Clin Exp Res 2016; 40:1832-45. [PMID: 27464336 DOI: 10.1111/acer.13159] [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: 02/15/2016] [Accepted: 06/23/2016] [Indexed: 12/25/2022]
Abstract
BACKGROUND Chronic alcohol consumption leads to a loss of white adipose tissue (WAT) but the underlying mechanisms for this lipodystrophy are not fully elucidated. This study tested the hypothesis that the reduction in WAT mass in chronic alcohol-fed mice is associated with a decreased protein synthesis specifically related to impaired function of mammalian target of rapamycin (mTOR). METHODS Adult male mice were provided an alcohol-containing liquid diet for 24 weeks or an isonitrogenous isocaloric control diet. In vivo protein synthesis was determined at this time and thereafter epididymal WAT (eWAT) was excised for analysis of signal transduction pathways central to controling protein synthesis and degradation. RESULTS While chronic alcohol feeding decreased whole-body and eWAT mass, this was associated with a discordant increase in protein synthesis in eWAT. This increase was not associated with a change in mTOR, 4E-BP1, Akt, or PRAS40 phosphorylation. Instead, a selective increase in phosphorylation of S6K1 and its downstream substrates, S6 and eIF4B was detected in alcohol-fed mice. Alcohol also increased eEF2K phosphorylation and decreased eEF2 phosphorylation consistent with increased translation elongation. Alcohol increased Atg12-5, LC3B-I and -II, and ULK1 S555 phosphorylation, suggesting increased autophagy, while markers of apoptosis (cleaved caspase-3 and -9, and PARP) were unchanged. Lipolytic enzymes (ATGL and HSL phosphorylation) were increased and lipogenic regulators (PPARγ and C/EBPα) were decreased in eWAT by alcohol. Although alcohol increased TNF-α, IL-6, and IL-1β mRNA, no change in key components of the NLRP3 inflammasome (NLRP3, ACS, and cleaved caspase-1) was detected suggesting alcohol did not increase pyroptosis. Plasma insulin did not differ between groups. CONCLUSIONS These results demonstrate that the alcohol-induced decrease in whole-body fat mass resulted in part from activation of autophagy in eWAT as protein synthesis was increased and mediated by the specific increase in the activity of S6K1.
Collapse
Affiliation(s)
- Kristen T Crowell
- Department of Cellular and Molecular Physiology, Penn State College Medicine, Hershey, Pennsylvania.,Department of Surgery, Penn State College Medicine, Hershey, Pennsylvania
| | - Jennifer L Steiner
- Department of Cellular and Molecular Physiology, Penn State College Medicine, Hershey, Pennsylvania
| | - Catherine S Coleman
- Department of Cellular and Molecular Physiology, Penn State College Medicine, Hershey, Pennsylvania
| | - Charles H Lang
- Department of Cellular and Molecular Physiology, Penn State College Medicine, Hershey, Pennsylvania.,Department of Surgery, Penn State College Medicine, Hershey, Pennsylvania
| |
Collapse
|
25
|
Potential Metabolic Biomarkers to Identify Interstitial Lung Abnormalities. Int J Mol Sci 2016; 17:ijms17071148. [PMID: 27438829 PMCID: PMC4964521 DOI: 10.3390/ijms17071148] [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: 03/23/2016] [Revised: 05/25/2016] [Accepted: 06/15/2016] [Indexed: 02/07/2023] Open
Abstract
Determining sensitive biomarkers in the peripheral blood to identify interstitial lung abnormalities (ILAs) is essential for the simple early diagnosis of ILAs. This study aimed to determine serum metabolic biomarkers of ILAs and the corresponding pathogenesis. Three groups of subjects undergoing health screening, including healthy subjects, subjects with ILAs, and subjects who were healthy initially and with ILAs one year later (Healthy→ILAs), were recruited for this study. The metabolic profiles of all of the subjects’ serum were analyzed by liquid chromatography quadruple time-of-flight mass spectrometry. The metabolic characteristics of the ILAs subjects were discovered, and the corresponding biomarkers were predicted. The metabolomic data from the Healthy→ILAs subjects were collected for further verification. The results indicated that five serum metabolite alterations (up-regulated phosphatidylcholine, phosphatidic acid, betaine aldehyde and phosphatidylethanolamine, as well as down-regulated 1-acylglycerophosphocholine) were sensitive and reliable biomarkers for identifying ILAs. Perturbation of the corresponding biological pathways (RhoA signaling, mTOR/P70S6K signaling and phospholipase C signaling) might be at least partially responsible for the pathogenesis of ILAs. This study may provide a good template for determining the early diagnostic markers of subclinical disease status and for obtaining a better understanding of their pathogenesis.
Collapse
|
26
|
Gao CQ, Zhi R, Yang Z, Li HC, Yan HC, Wang XQ. Low dose of IGF-I increases cell size of skeletal muscle satellite cells via Akt/S6K signaling pathway. J Cell Biochem 2016; 116:2637-48. [PMID: 25923195 DOI: 10.1002/jcb.25212] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 04/22/2015] [Indexed: 12/17/2022]
Abstract
The objective of this study was to investigate the effect of insulin growth factor-I (IGF-I) on the size of pig skeletal muscle satellite cells (SCs). Using microarray, real-time RT-PCR, radioimmunoassay analysis and western blot, we first showed that supplementation of low-dose of IGF-I in culture medium resulted in enlarged cell size of Lantang SCs, only Akt and S6K were up-regulated at both the mRNA and protein levels among almost all of the mTOR pathway key genes, but had no effect on cell number. To elucidate the signaling mechanisms responsible for regulating cell size under low-dose of IGF-I treatment, we blocked Akt and S6K activity with the specific inhibitors MK2206 and PF4708671, respectively. Both inhibitors caused a decrease in cell size. In addition, MK2206 lowered the protein level of p-Akt (Ser473), p-S6K (Thr389), and p-rpS6 (Ser235/236), whereas PF4708671 lowered the protein level of p-S6K (Thr389) and p-rpS6 (Ser235/236). However, low dose of IGF-I didn't affect the protein level of p-mTOR (Ser2448) and p-mTOR (Ser2481). When both inhibitors were applied simultaneously, the effect was the same as that of the Akt inhibition alone. Taken together, we report for the first time that low-dose of IGF-I treatment increases cell size via Akt/S6K signaling pathway.
Collapse
Affiliation(s)
- Chun-qi Gao
- College of Animal Science, South China Agricultural University/National Engineering Research Center for Breeding Swine Industry/Guangdong Provincial Key Laboratory of Agro-Animal Genomics, Guangzhou, Guangdong province, China
| | - Rui Zhi
- College of Animal Science, South China Agricultural University/National Engineering Research Center for Breeding Swine Industry/Guangdong Provincial Key Laboratory of Agro-Animal Genomics, Guangzhou, Guangdong province, China.,Guizhou Agricultural Vocational College, Guiyang, Guizhou, China
| | - Zhou Yang
- College of Animal Science, South China Agricultural University/National Engineering Research Center for Breeding Swine Industry/Guangdong Provincial Key Laboratory of Agro-Animal Genomics, Guangzhou, Guangdong province, China.,College of Science and Engineering, Guangxi Open University, Nanning, Guangxi, China
| | - Hai-chang Li
- Davis Heart & Lung Research Institute, Wexner Medical Center at the Ohio State University, Columbus, Ohio
| | - Hui-chao Yan
- College of Animal Science, South China Agricultural University/National Engineering Research Center for Breeding Swine Industry/Guangdong Provincial Key Laboratory of Agro-Animal Genomics, Guangzhou, Guangdong province, China
| | - Xiu-qi Wang
- College of Animal Science, South China Agricultural University/National Engineering Research Center for Breeding Swine Industry/Guangdong Provincial Key Laboratory of Agro-Animal Genomics, Guangzhou, Guangdong province, China
| |
Collapse
|
27
|
A Repertoire of MicroRNAs Regulates Cancer Cell Starvation by Targeting Phospholipase D in a Feedback Loop That Operates Maximally in Cancer Cells. Mol Cell Biol 2016; 36:1078-89. [PMID: 26787840 DOI: 10.1128/mcb.00711-15] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 01/11/2016] [Indexed: 02/07/2023] Open
Abstract
We report a negative feedback loop between the signaling protein phospholipase D (PLD), phosphatidic acid (PA), and a specific set of microRNAs (miRNAs) during nutrient starvation of breast cancer cells. We show that PLD expression is increased in four breast cancer cell lines and that hypoxia, cell overcrowding, and nutrient starvation for 3 to 6 h increase expression even further. However, after prolonged (>12-h) starvation, PLD levels return to basal or lower levels. The mechanism for this is as follows. First, during initial starvation, an elevated PA (the product of PLD enzymatic activity) activates mTOR and S6K, known to inhibit apoptosis, and enhances cell migration especially in post-epithelial-to-mesenchymal transition (post-EMT) cancer cells. Second, continued PA production in later starvation induces expression of PLD-targeting microRNA 203 (miR-203), miR-887, miR-3619-5p, and miR-182, which reduce PLD translation. We provide direct evidence for a feedback loop, whereby PLD induction upon starvation leads to PA, which induces expression of miRNAs, which in turn inhibits PLD2 translation. The physiological relevance for breast cancer cells is that as PA can activate cell invasion, then, due to the negative feedback, it can deprive mTOR and S6K of their natural activator. It can further prevent inhibition of apoptosis and allow cells to survive nutrient deprivation, which normal cells cannot do.
Collapse
|
28
|
NSCLC cells demonstrate differential mode of cell death in response to the combined treatment of radiation and a DNA-PKcs inhibitor. Oncotarget 2016; 6:3848-60. [PMID: 25714019 PMCID: PMC4414158 DOI: 10.18632/oncotarget.2975] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 12/20/2014] [Indexed: 12/19/2022] Open
Abstract
The current standard of care for lung cancer consists of concurrent chemotherapy and radiation. Several studies have shown that the DNA-PKcs inhibitor NU7441 is a highly potent radiosensitizer, however, the mechanism of NU7441's anti-proliferation effect has not been fully elucidated. In this study, the combined effect of NU7441 and ionizing radiation (IR) in a panel of non-small cell lung cancer cell lines (A549, H460 and H1299) has been investigated. We found that NU7441 significantly enhances the effect of IR in all cell lines. The notable findings in response to this combined treatment are (i) prolonged delay in IR-induced DNA DSB repair, (ii) induced robust G2/M checkpoint, (iii) increased aberrant mitosis followed by mitotic catastrophe specifically in H1299, (iv) dramatically induced autophagy in A549 and (v) IR-induced senescence specifically in H460. H1299 cells show greater G2 checkpoint adaptation after combined treatment, which can be attributed to higher expression level of Plk1 compared to A549 and H460. The enhanced autophagy after NU7441 treatment in A549 is possibly due to the higher endogenous expression of pS6K compared to H1299 and H460 cells. In conclusion, choice of cell death pathway is dependent on the mutation status and other genetic factors of the cells treated.
Collapse
|
29
|
Phosphatidic Acid (PA) can Displace PPARα/LXRα Binding to The EGFR Promoter Causing its Transrepression in Luminal Cancer Cells. Sci Rep 2015; 5:15379. [PMID: 26493292 PMCID: PMC4615983 DOI: 10.1038/srep15379] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 08/24/2015] [Indexed: 12/14/2022] Open
Abstract
The expression of the epidermal growth factor receptor (EGFR) is highly regulated in normal cells, whereas some cancer cells have high constitutive levels. Understanding naturally-occurring ways of downregulating EGFR in cancer cells was investigated. Phosphatidic acid (PA) or Nuclear Receptors (NR) PPARα/RXRα/LXRα, enhance EGFR expression, mediated by the promoter region -856(A) to -226(T). Unexpectedly, the combination of NRs and PA caused repression. PA induces a conformational change in the nuclear receptor PPARα (increase of alpha-helices at the expense of decreasing beta-sheets), as evidenced by circular dichroism. This represses the naturally-enhancing capability of PPARα on EGFR transcription. PPARα-overexpressing cells in the presence of PA > 300 nM or the enzyme that produces it, phospholipase D (PLD), downregulate EGFR expression. The reasons are two-fold. First, PA displaces PPARα binding to the EGFR promoter at those concentrations. Second, NR heterodimer-dependent promoter activity is weakened in the presence of PA in vivo. Since other genes considered (β-catenin, cyclin D3, PLD2 and ACOX-1) are also downregulated with a PA + PPARα combination, the transrepression appears to be a global phenomenon. Lastly, the reported effect is greater in MCF-7 than in MDA-MB-231 breast cancer cells, which could provide a novel basis for regulating excessive expression of EGFR in luminal cancer cells.
Collapse
|
30
|
Bruntz RC, Lindsley CW, Brown HA. Phospholipase D signaling pathways and phosphatidic acid as therapeutic targets in cancer. Pharmacol Rev 2015; 66:1033-79. [PMID: 25244928 DOI: 10.1124/pr.114.009217] [Citation(s) in RCA: 161] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Phospholipase D is a ubiquitous class of enzymes that generates phosphatidic acid as an intracellular signaling species. The phospholipase D superfamily plays a central role in a variety of functions in prokaryotes, viruses, yeast, fungi, plants, and eukaryotic species. In mammalian cells, the pathways modulating catalytic activity involve a variety of cellular signaling components, including G protein-coupled receptors, receptor tyrosine kinases, polyphosphatidylinositol lipids, Ras/Rho/ADP-ribosylation factor GTPases, and conventional isoforms of protein kinase C, among others. Recent findings have shown that phosphatidic acid generated by phospholipase D plays roles in numerous essential cellular functions, such as vesicular trafficking, exocytosis, autophagy, regulation of cellular metabolism, and tumorigenesis. Many of these cellular events are modulated by the actions of phosphatidic acid, and identification of two targets (mammalian target of rapamycin and Akt kinase) has especially highlighted a role for phospholipase D in the regulation of cellular metabolism. Phospholipase D is a regulator of intercellular signaling and metabolic pathways, particularly in cells that are under stress conditions. This review provides a comprehensive overview of the regulation of phospholipase D activity and its modulation of cellular signaling pathways and functions.
Collapse
Affiliation(s)
- Ronald C Bruntz
- Department of Pharmacology (R.C.B., C.W.L., H.A.B.) and Vanderbilt Center for Neuroscience Drug Discovery (C.W.L.), Vanderbilt University Medical Center; Department of Chemistry, Vanderbilt Institute of Chemical Biology (C.W.L., H.A.B.); Vanderbilt Specialized Chemistry for Accelerated Probe Development (C.W.L.); and Department of Biochemistry, Vanderbilt-Ingram Cancer Center (H.A.B.), Vanderbilt University, Nashville, Tennessee
| | - Craig W Lindsley
- Department of Pharmacology (R.C.B., C.W.L., H.A.B.) and Vanderbilt Center for Neuroscience Drug Discovery (C.W.L.), Vanderbilt University Medical Center; Department of Chemistry, Vanderbilt Institute of Chemical Biology (C.W.L., H.A.B.); Vanderbilt Specialized Chemistry for Accelerated Probe Development (C.W.L.); and Department of Biochemistry, Vanderbilt-Ingram Cancer Center (H.A.B.), Vanderbilt University, Nashville, Tennessee
| | - H Alex Brown
- Department of Pharmacology (R.C.B., C.W.L., H.A.B.) and Vanderbilt Center for Neuroscience Drug Discovery (C.W.L.), Vanderbilt University Medical Center; Department of Chemistry, Vanderbilt Institute of Chemical Biology (C.W.L., H.A.B.); Vanderbilt Specialized Chemistry for Accelerated Probe Development (C.W.L.); and Department of Biochemistry, Vanderbilt-Ingram Cancer Center (H.A.B.), Vanderbilt University, Nashville, Tennessee
| |
Collapse
|
31
|
Shad BJ, Smeuninx B, Atherton PJ, Breen L. The mechanistic and ergogenic effects of phosphatidic acid in skeletal muscle. Appl Physiol Nutr Metab 2015; 40:1233-41. [PMID: 26566242 DOI: 10.1139/apnm-2015-0350] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Skeletal muscle mass plays a vital role in locomotion, whole-body metabolic health, and is a positive predictor of longevity. It is well established the mammalian target of rapamycin (mTOR) is a central regulator of skeletal muscle protein turnover. The pursuit to find novel nutrient compounds or functional food sources that possess the ability to activate mTOR and promote skeletal muscle protein accretion has been on going. Over the last decade, a key role has been proposed for the phospholipid phosphatidic acid (PA) in mTOR activation. Mechanical load-induced (i.e., resistance exercise) intramuscular PA can directly bind to and activate mTOR. In addition, PA provided exogenously in cell culture heightens mTOR activity, albeit indirectly. Thus, endogenously generated PA and exogenous provision of PA appear to act through distinct mechanisms that converge on mTOR and, potentially, may amplify muscle protein synthesis. In support of this notion, limited evidence from humans suggests that resistance exercise training combined with oral supplemental PA enhances strength gains and muscle hypertrophy. However, the precise mechanisms underpinning the augmented muscle remodelling response with supplemental PA remain elusive. In this review, we will critically examine available evidence from cell cultures and animal and human experimental models to provide an overview of the mechanisms through which endogenous and exogenous PA may act to promote muscle anabolism, and discuss the potential for PA as a therapeutic tool to maintain or restore skeletal muscle mass in the context of ageing and disease.
Collapse
Affiliation(s)
- Brandon James Shad
- a School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Benoit Smeuninx
- a School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Philip James Atherton
- b MRC-ARUK Centre for Excellence in Musculoskeletal Ageing Research, Birmingham, UK.,c Clinical, Metabolic and Molecular Physiology, University of Nottingham, Royal Derby Hospital, Nottingham, DE22 3DT, UK
| | - Leigh Breen
- b MRC-ARUK Centre for Excellence in Musculoskeletal Ageing Research, Birmingham, UK.,d School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, UK
| |
Collapse
|
32
|
Mobley CB, Hornberger TA, Fox CD, Healy JC, Ferguson BS, Lowery RP, McNally RM, Lockwood CM, Stout JR, Kavazis AN, Wilson JM, Roberts MD. Effects of oral phosphatidic acid feeding with or without whey protein on muscle protein synthesis and anabolic signaling in rodent skeletal muscle. J Int Soc Sports Nutr 2015; 12:32. [PMID: 26279644 PMCID: PMC4537536 DOI: 10.1186/s12970-015-0094-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 08/09/2015] [Indexed: 11/10/2022] Open
Abstract
Background Phosphatidic acid (PA) is a diacyl-glycerophospholipid that acts as a signaling molecule in numerous cellular processes. Recently, PA has been proposed to stimulate skeletal muscle protein accretion, but mechanistic studies are lacking. Furthermore, it is unknown whether co-ingesting PA with other leucine-containing ingredients can enhance intramuscular anabolic signaling mechanisms. Thus, the purpose of this study was to examine if oral PA feeding acutely increases anabolic signaling markers and muscle protein synthesis (MPS) in gastrocnemius with and without whey protein concentrate (WPC). Methods Overnight fasted male Wistar rats (~250 g) were randomly assigned to four groups: control (CON, n = 6-13), PA (29 mg; n = 8), WPC (197 mg; n = 8), or PA + WPC (n = 8). Three hours post-feeding, gastrocnemius muscle was removed for markers of Akt-mTOR signaling, gene expression patterns related to skeletal muscle mass regulation and metabolism, and MPS analysis via the SUnSET method. Results Compared to CON rats, PA, WPC and PA + WPC resulted in a significant elevation in the phosphorylation of mTOR (Ser2481) and rps6 (Ser235/236) (p < 0.05) in the gastrocnemius though there were no differences between the supplemented groups. MPS levels in the gastrocnemius were significantly (p < 0.05) elevated in WPC versus CON rats, and tended to be elevated in PA versus CON rats (p = 0.08), though MPS was less in PA + WPC versus WPC rats (p < 0.05) in spite of robust increases in mTOR pathway activity markers in the former group. C2C12 myoblast data agreed with the in vivo data herein showing that PA increased MPS levels 51 % (p < 0.001) phosphorylated p70s6k (Thr389) levels 67 % (p < 0.001). Conclusions Our results are the first in vivo evidence to demonstrate that PA tends to increases MPS 3 h post-feeding, though PA may delay WPC-mediated MPS kinetics within a 3 h post-feeding window.
Collapse
Affiliation(s)
| | - Troy A Hornberger
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI USA
| | - Carlton D Fox
- School of Kinesiology, Auburn University, Auburn, AL USA
| | - James C Healy
- School of Kinesiology, Auburn University, Auburn, AL USA
| | | | - Ryan P Lowery
- Department of Health Sciences and Human Performance, University of Tampa, Tampa, FL USA
| | - Rachel M McNally
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI USA
| | | | - Jeffrey R Stout
- Human Performance Laboratory, University of Central Florida, Orlando, FL USA
| | | | - Jacob M Wilson
- Department of Health Sciences and Human Performance, University of Tampa, Tampa, FL USA
| | | |
Collapse
|
33
|
Phosphatidic Acid Increases Epidermal Growth Factor Receptor Expression by Stabilizing mRNA Decay and by Inhibiting Lysosomal and Proteasomal Degradation of the Internalized Receptor. Mol Cell Biol 2015; 35:3131-44. [PMID: 26124282 DOI: 10.1128/mcb.00286-15] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2015] [Accepted: 06/22/2015] [Indexed: 12/18/2022] Open
Abstract
Overexpression of epidermal growth factor receptor (EGFR) is one of the frequent mechanisms implicated in cancer progression, and so is the overexpression of the enzyme phospholipase D (PLD) and its reaction product, phosphatidic acid (PA). However, an understanding of how these signaling molecules interact at the level of gene expression is lacking. Catalytically active PLD enhanced expression of EGFR in human breast cancer cells. Overexpression of the PLD2 isoform increased EGFR mRNA and protein expression. It also negated an EGFR downregulation mediated by small interfering RNA targeting EGFR (siEGFR). Several mechanisms contributed to the alteration in EGFR expression. First was the stabilization of EGFR transcripts as PLD2 delayed mRNA decay, which prolonged their half-lives. Second, RNase enzymatic activity was inhibited by PA. Third, protein stabilization also occurred, as indicated by PLD resistance to cycloheximide-induced EGFR protein degradation. Fourth, PA inhibited lysosomal and proteasomal degradation of internalized EGFR. PLD2 and EGFR colocalized at the cell membrane, and JAK3 phosphorylation at Tyr980/Tyr981 followed receptor endocytosis. Further, the presence of PLD2 increased stabilization of intracellular EGFR in large recycling vesicles at ∼15 min of EGF stimulation. Thus, PLD2-mediated production of PA contributed to the control of EGFR exposure to ligand through a multipronged transcriptional and posttranscriptional program during the out-of-control accumulation of EGFR signaling in cancer cells.
Collapse
|
34
|
Two sites of action for PLD2 inhibitors: The enzyme catalytic center and an allosteric, phosphoinositide biding pocket. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1851:261-72. [PMID: 25532944 DOI: 10.1016/j.bbalip.2014.12.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 12/02/2014] [Accepted: 12/09/2014] [Indexed: 12/17/2022]
Abstract
Phospholipase D (PLD) has been implicated in many physiological functions, such as chemotaxis and phagocytosis, as well as pathological functions, such as cancer cell invasion and metastasis. New inhibitors have been described that hamper the role of PLD in those pathologies but their site of action is not known. We have characterized the biochemical and biological behavior of the PLD1/2 dual inhibitor 5-Fluoro-2-indolyl des-chlorohalopemide (FIPI), and the specific PLD2 inhibitor, N-[2-[1-(3-Fluorophenyl)-4-oxo-1,3,-8-triazaspiro[4.5]dec-8-yl]ethyl]-2-naphthalenecarboxamide (NFOT), and found that both FIPI and NFOT are mixed-kinetics inhibitors. Mutagenesis studies indicate that FIPI binds at S757 of PLD2, which is within the HKD2 catalytic site of the enzyme, whereas NFOT binds to PLD2 at two different sites, one being at S757/S648 and another to an allosteric site that is a natural site occupied by PIP2 (R210/R212). This latter site, along with F244/L245/L246, forms a hydrophobic pocket in the PH domain. The mechanism of action of FIPI is a direct effect on the catalytic site (and as such inhibits both PLD1 and PLD2 isoforms), whereas PLD2 affects both the catalytic site (orthosteric) and blocks PIP2 binding to PLD2 (allosteric), which negates the natural enhancing role of PIP2. Moreover, NFOT prevents cell invasion of cancer cells, which does not occur in cells overexpressing PLD2-F244A/L245A/L246A, or PLD2-R210A/R212A, or PLD2-S757/S648 mutants. This study provides new specific knowledge of enzyme regulation and mechanisms of activation and inhibition of PLD2 that are necessary to understand its role in cell signaling and to develop new inhibitors for cancer cell invasion and metastasis.
Collapse
|
35
|
Henkels KM, Mallets ER, Dennis PB, Gomez-Cambronero J. S6K is a morphogenic protein with a mechanism involving Filamin-A phosphorylation and phosphatidic acid binding. FASEB J 2014; 29:1299-313. [PMID: 25512366 DOI: 10.1096/fj.14-260992] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 11/18/2014] [Indexed: 01/13/2023]
Abstract
Change of cell shape in vivo plays many roles that are central to life itself, such as embryonic development, inflammation, wound healing, and pathologic processes such as cancer metastasis. Nonetheless, the spatiotemporal mechanisms that control the concerted regulation of cell shape remain understudied. Here, we show that ribosomal S6K, which is normally considered a protein involved in protein translation, is a morphogenic protein. Its presence in cells alters the overall organization of the cell surface and cell circularity [(4π × area)/(perimeter)(2)] from 0.47 ± 0.06 units in mock-treated cells to 0.09 ± 0.03 units in S6K-overexpressing macrophages causing stellation and arborization of cell shape. This effect was partially reversed in cells expressing a kinase-inactive S6K mutant and was fully reversed in cells silenced with small interference RNA. Equally important is that S6K is itself regulated by phospholipids, specifically phosphatidic acid, whereby 300 nM 1,2-dioleoyl-sn-glycero-3-phosphate (DOPA), but not the control 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), binds directly to S6K and causes an ∼ 2.9-fold increase in S6K catalytic activity. This was followed by an increase in Filamin A (FLNA) functionality as measured by phospho-FLNA (S(2152)) expression and by a subsequent elevation of actin nucleation. This reliance of S6K on phosphatidic acid (PA), a curvature-inducing phospholipid, explained the extra-large perimeter of cells that overexpressed S6K. Furthermore, the diversity of the response to S6K in several unrelated cell types (fibroblasts, leukocytes, and invasive cancer cells) that we report here indicates the existence of an underlying common mechanism in mammalian cells. This new signaling set, PA-S6K-FLNA-actin, sheds light for the first time into the morphogenic pathway of cytoskeletal structures that are crucial for adhesion and cell locomotion during inflammation and metastasis.
Collapse
Affiliation(s)
- Karen M Henkels
- *Wright State University School of Medicine, Department of Biochemistry and Molecular Biology, Dayton, Ohio, USA; and Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio, USA
| | - Elizabeth R Mallets
- *Wright State University School of Medicine, Department of Biochemistry and Molecular Biology, Dayton, Ohio, USA; and Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio, USA
| | - Patrick B Dennis
- *Wright State University School of Medicine, Department of Biochemistry and Molecular Biology, Dayton, Ohio, USA; and Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio, USA
| | - Julian Gomez-Cambronero
- *Wright State University School of Medicine, Department of Biochemistry and Molecular Biology, Dayton, Ohio, USA; and Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio, USA
| |
Collapse
|
36
|
Joy JM, Gundermann DM, Lowery RP, Jäger R, McCleary SA, Purpura M, Roberts MD, Wilson SM, Hornberger TA, Wilson JM. Phosphatidic acid enhances mTOR signaling and resistance exercise induced hypertrophy. Nutr Metab (Lond) 2014; 11:29. [PMID: 24959196 PMCID: PMC4066292 DOI: 10.1186/1743-7075-11-29] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 06/07/2014] [Indexed: 01/03/2023] Open
Abstract
Introduction The lipid messenger phosphatidic acid (PA) plays a critical role in the stimulation of mTOR signaling. However, the mechanism by which PA stimulates mTOR is currently unknown. Therefore, the purpose of this study was to compare the effects of various PA precursors and phospholipids on their ability to stimulate mTOR signaling and its ability to augment resistance training-induced changes in body composition and performance. Methods In phase one, C2C12 myoblasts cells were stimulated with different phospholipids and phospholipid precursors derived from soy and egg sources. The ratio of phosphorylated p70 (P-p70-389) to total p70 was then used as readout for mTOR signaling. In phase two, resistance trained subjects (n = 28, 21 ± 3 years, 77 ± 4 kg, 176 ± 9 cm) consumed either 750 mg PA daily or placebo and each took part in an 8 week periodized resistance training program. Results In phase one, soy-phosphatidylserine, soy-Lyso-PA, egg-PA, and soy-PA stimulated mTOR signaling, and the effects of soy-PA (+636%) were significantly greater than egg-PA (+221%). In phase two, PA significantly increased lean body mass (+2.4 kg), cross sectional area (+1.0 cm), and leg press strength (+51.9 kg) over placebo. Conclusion PA significantly activates mTOR and significantly improved responses in skeletal muscle hypertrophy, lean body mass, and maximal strength to resistance exercise.
Collapse
Affiliation(s)
- Jordan M Joy
- Department of Health Sciences and Human Performance, The University of Tampa, 401 W. Kennedy Blvd., Box 30 F, Tampa, FL 33606, USA
| | - David M Gundermann
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Ryan P Lowery
- Department of Health Sciences and Human Performance, The University of Tampa, 401 W. Kennedy Blvd., Box 30 F, Tampa, FL 33606, USA
| | - Ralf Jäger
- Increnovo LLC, 2138 E Lafayette Pl, Milwaukee, WI 53202, USA
| | - Sean A McCleary
- Department of Health Sciences and Human Performance, The University of Tampa, 401 W. Kennedy Blvd., Box 30 F, Tampa, FL 33606, USA
| | - Martin Purpura
- Increnovo LLC, 2138 E Lafayette Pl, Milwaukee, WI 53202, USA
| | | | | | - Troy A Hornberger
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Jacob M Wilson
- Department of Health Sciences and Human Performance, The University of Tampa, 401 W. Kennedy Blvd., Box 30 F, Tampa, FL 33606, USA
| |
Collapse
|
37
|
Moore SF, Hunter RW, Hers I. Protein kinase C and P2Y12 take center stage in thrombin-mediated activation of mammalian target of rapamycin complex 1 in human platelets. J Thromb Haemost 2014; 12:748-60. [PMID: 24612393 PMCID: PMC4238809 DOI: 10.1111/jth.12552] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 02/25/2014] [Indexed: 01/24/2023]
Abstract
BACKGROUND Rapamycin, an inhibitor of mammalian target of rapamycin complex-1 (mTORC1), reduces platelet spreading, thrombus stability, and clot retraction. Despite an important role of mTORC1 in platelet function, little is known about how it is regulated. The objective of this study was to determine the signaling pathways that regulate mTORC1 in human platelets. METHODS Mammalian target of rapamycin complex-1 activation was assessed by measuring the phosphorylation of its downstream substrate ribosomal S6 kinase 1 (p70S6K). RESULTS Thrombin or the protein kinase C (PKC) activator phorbal 12-myristate 13-acetate stimulated activation of mTORC1 in a PKC-dependent, Akt-independent manner that correlated with phosphorylation of tuberin/tuberous sclerosis 2 (TSC2) (Ser939 and Thr1462). In contrast, insulin-like growth factor 1 (IGF-1)-stimulated TSC2 phosphorylation was completely dependent on phosphoinositide 3 kinase (PI3 kinase)/Akt but did not result in any detectable mTORC1 activation. Early (Ser939 and Thr1462) and late (Thr1462) TSC2 phosphorylation in response to thrombin were directly PKC dependent, whereas later TSC2 (Ser939) and p70S6K phosphorylation were largely dependent on paracrine signaling through P2Y(12). PKC-mediated adenosine diphosphate (ADP) secretion was essential for thrombin-stimulated mTORC1 activation, as (i) ADP rescued p70S6K phosphorylation in the presence of a PKC inhibitor and (ii) P2Y(12) antagonism prevented thrombin-mediated mTORC1 activation. Rescue of mTORC1 activation with exogenous ADP was completely dependent on the Src family kinases but independent of PI3 kinase/Akt. Interestingly, although inhibition of Src blocked the ADP rescue, it had little effect on thrombin-stimulated p70S6K phosphorylation under conditions where PKC was not inhibited. CONCLUSION These results demonstrate that thrombin activates the mTORC1 pathway in human platelets through PKC-mediated ADP secretion and subsequent activation of P2Y(12), in a manner largely independent of the canonical PI3 kinase/Akt pathway.
Collapse
Affiliation(s)
- S F Moore
- School of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol, UK
| | | | | |
Collapse
|
38
|
Abstract
Phosphatidic acid (PA) is recognized as an important class of lipid messengers. The cellular PA levels are dynamic; PA is produced and metabolized by several enzymatic reactions, including different phospholipases, lipid kinases, and phosphatases. PA interacts with various proteins and the interactions may modulate enzyme catalytic activities and/or tether proteins to membranes. The PA-protein interactions are impacted by changes in cellular pH and other effectors, such as cations. PA is involved in a wide range of cellular processes, including vesicular trafficking, cytoskeletal organization, secretion, cell proliferation, and survival. Manipulations of different PA production reactions alter cellular and organismal response to a wide range of abiotic and biotic stresses. Further investigations of PA's function and mechanisms of action will advance not only the understanding of cell signaling networks but also may lead to biotechnological and pharmacological applications.
Collapse
|
39
|
Abstract
Markers of cellular senescence depend in part on the MTOR (mechanistic target of rapamycin) pathway. MTOR participates in geroconversion, a conversion from reversible cell cycle arrest to irreversible senescence. Recently we demonstrated that hyper-induction of cyclin D1 during geroconversion was mostly dependent on MEK, whereas rapamycin only partially inhibited cyclin D1 accumulation. Here we show that, while not affecting cyclin D1, siRNA for p70S6K partially prevented loss of RP (replicative/regenerative potential) during p21-induced cell cycle arrest. Similarly, an inhibitor of p70 S6 kinase (PF-4708671) partially inhibited phosphorylation of S6 and preserved RP, while only marginally prevented cyclin D1 induction. Thus S6K and MEK play different roles in geroconversion.
Collapse
Affiliation(s)
- Olga V Leontieva
- Department of Cell Stress Biology; Roswell Park Cancer Institute; Buffalo, NY USA
| | | | | |
Collapse
|
40
|
Liu Y, Käch A, Ziegler U, Ong ACM, Wallace DP, Arcaro A, Serra AL. The role of phospholipase D in modulating the MTOR signaling pathway in polycystic kidney disease. PLoS One 2013; 8:e73173. [PMID: 24009738 PMCID: PMC3751888 DOI: 10.1371/journal.pone.0073173] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 07/17/2013] [Indexed: 12/17/2022] Open
Abstract
The mammalian target of rapamycin (mTOR) signaling pathway is aberrantly activated in polycystic kidney disease (PKD). Emerging evidence suggests that phospholipase D (PLD) and its product phosphatidic acid (PA) regulate mTOR activity. In this study, we assessed in vitro the regulatory function of PLD and PA on the mTOR signaling pathway in PKD. We found that the basal level of PLD activity was elevated in PKD cells. Targeting PLD by small molecule inhibitors reduced cell proliferation and blocked mTOR signaling, whereas exogenous PA stimulated mTOR signaling and abolished the inhibitory effect of PLD on PKD cell proliferation. We also show that blocking PLD activity enhanced the sensitivity of PKD cells to rapamycin and that combining PLD inhibitors and rapamycin synergistically inhibited PKD cell proliferation. Furthermore, we demonstrate that targeting mTOR did not induce autophagy, whereas targeting PLD induced autophagosome formation. Taken together, our findings suggest that deregulated mTOR pathway activation is mediated partly by increased PLD signaling in PKD cells. Targeting PLD isoforms with pharmacological inhibitors may represent a new therapeutic strategy in PKD.
Collapse
Affiliation(s)
- Yang Liu
- Institute of Physiology, University of Zurich, Zürich, Switzerland
| | - Andres Käch
- Center for Microscopy and Image Analysis, University of Zurich, Zürich, Switzerland
| | - Urs Ziegler
- Center for Microscopy and Image Analysis, University of Zurich, Zürich, Switzerland
| | - Albert C. M. Ong
- Academic Unit of Nephrology, Department of Infection and Immunity, University of Sheffield, Sheffield, United Kingdom
| | - Darren P. Wallace
- Department of Medicine, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Alexandre Arcaro
- Department of Clinical Research, University of Bern, Bern, Switzerland
| | - Andreas L. Serra
- Institute of Physiology, University of Zurich, Zürich, Switzerland
- * E-mail:
| |
Collapse
|
41
|
Hong-Brown LQ, Brown CR, Navaratnarajah M, Lang CH. Activation of AMPK/TSC2/PLD by alcohol regulates mTORC1 and mTORC2 assembly in C2C12 myocytes. Alcohol Clin Exp Res 2013; 37:1849-61. [PMID: 23895284 DOI: 10.1111/acer.12174] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 04/03/2013] [Indexed: 01/02/2023]
Abstract
BACKGROUND Ethanol (EtOH) decreases muscle protein synthesis, and this is associated with reduced mammalian target of rapamycin complex (mTORC)1 and increased mTORC2 activities. In contrast, phospholipase D (PLD) and its metabolite phosphatidic acid (PA) positively regulate mTORC1 signaling, whereas their role in mTORC2 function is less well defined. Herein, we examine the role that PLD and PA play in EtOH-mediated mTOR signaling. METHODS C2C12 myoblasts were incubated with EtOH for 18 to 24 hours. For PA experiments, cells were pretreated with the drug for 25 minutes followed by 50-minute incubation with PA in the presence or absence of EtOH. The phosphorylation state of various proteins was assessed by immunoblotting. Protein-protein interactions were determined by immunoprecipitation and immunoblotting. PLD activity was measured using the Amplex Red PLD assay kit. PA concentrations were determined with a total PA assay kit. RESULTS PA levels and PLD activity increased in C2C12 myocytes exposed to EtOH (100 mM). Increased PLD activity was blocked by inhibitors of AMP-activated protein kinase (AMPK) (compound C) and phosphoinositide 3-kinase (PI3K) (wortmannin). Likewise, suppression of PLD activity with CAY10594 prevented EtOH-induced Akt (S473) phosphorylation. PLD inhibition also enhanced the binding of Rictor to mSin1 and the negative regulatory proteins Deptor and 14-3-3. Addition of PA to myocytes decreased Akt phosphorylation, but changes in mTORC2 activity were not associated with altered binding of complex members and 14-3-3. PA increased S6K1 phosphorylation, with the associated increase in mTORC1 activity being regulated by reduced phosphorylation of AMPKα (T172) and its target tuberous sclerosis protein complex (TSC)2 (S1387). This resulted in increased Rheb and RagA/RagC GTPase interactions with mTOR, as well as suppression of mTORC2. CONCLUSIONS EtOH-induced increases in PLD activity and PA may partially counterbalance the adverse effects of this agent. EtOH and PA regulate mTORC1 via a PI3K/AMPK/TSC2/PLD signaling cascade. PA stimulates mTORC1 function and suppresses activation of mTORC2 as part of an mTORC1/2 feedback loop.
Collapse
Affiliation(s)
- Ly Q Hong-Brown
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, Pennsylvania
| | | | | | | |
Collapse
|
42
|
Schoenfeld BJ. Potential mechanisms for a role of metabolic stress in hypertrophic adaptations to resistance training. Sports Med 2013; 43:179-94. [PMID: 23338987 DOI: 10.1007/s40279-013-0017-1] [Citation(s) in RCA: 260] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
It is well established that regimented resistance training can promote increases in muscle hypertrophy. The prevailing body of research indicates that mechanical stress is the primary impetus for this adaptive response and studies show that mechanical stress alone can initiate anabolic signalling. Given the dominant role of mechanical stress in muscle growth, the question arises as to whether other factors may enhance the post-exercise hypertrophic response. Several researchers have proposed that exercise-induced metabolic stress may in fact confer such an anabolic effect and some have even suggested that metabolite accumulation may be more important than high force development in optimizing muscle growth. Metabolic stress pursuant to traditional resistance training manifests as a result of exercise that relies on anaerobic glycolysis for adenosine triphosphate production. This, in turn, causes the subsequent accumulation of metabolites, particularly lactate and H(+). Acute muscle hypoxia associated with such training methods may further heighten metabolic buildup. Therefore, the purpose of this paper will be to review the emerging body of research suggesting a role for exercise-induced metabolic stress in maximizing muscle development and present insights as to the potential mechanisms by which these hypertrophic adaptations may occur. These mechanisms include increased fibre recruitment, elevated systemic hormonal production, alterations in local myokines, heightened production of reactive oxygen species and cell swelling. Recommendations are provided for potential areas of future research on the subject.
Collapse
Affiliation(s)
- Brad J Schoenfeld
- Department of Health Sciences, Program of Exercise Science, APEX Building, Room # 265, Lehman College, CUNY, 250 Bedford Park Blvd West, Bronx, NY 10468, USA.
| |
Collapse
|
43
|
Carnevale J, Ross L, Puissant A, Banerji V, Stone RM, DeAngelo DJ, Ross KN, Stegmaier K. SYK regulates mTOR signaling in AML. Leukemia 2013; 27:2118-28. [PMID: 23535559 PMCID: PMC4028963 DOI: 10.1038/leu.2013.89] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 03/11/2013] [Accepted: 03/18/2013] [Indexed: 12/17/2022]
Abstract
Spleen Tyrosine Kinase (SYK) was recently identified as a new target in acute myeloid leukemia (AML); however, its mechanistic role in this disease is poorly understood. Based on the known interaction between SYK and mTOR signaling in lymphoma, we hypothesized that SYK may regulate mTOR signaling in AML. Both small-molecule inhibition of SYK and SYK-directed shRNA suppressed mTOR and its downstream signaling effectors, as well as its upstream activator, AKT. Moreover, the inhibition of multiple nodes of the PI3K signaling pathway enhanced the effects of SYK suppression on AML cell viability and differentiation. Evaluation of the collateral MAPK pathway revealed a heterogeneous response to SYK inhibition in AML with down-regulation of MEK and ERK phosphorylation in some AML cell lines but a paradoxical increase in MEK/ERK phosphorylation in RAS-mutated AML. These studies reveal SYK as a regulator of mTOR and MAPK signaling in AML and demonstrate that inhibition of PI3K pathway activity enhances the effects of SYK inhibition on AML cell viability and differentiation.
Collapse
Affiliation(s)
- J Carnevale
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Children's Hospital Boston, Harvard Medical School, Boston, MA, USA
| | | | | | | | | | | | | | | |
Collapse
|
44
|
Mahankali M, Henkels KM, Gomez-Cambronero J. A GEF-to-phospholipase molecular switch caused by phosphatidic acid, Rac and JAK tyrosine kinase that explains leukocyte cell migration. J Cell Sci 2013; 126:1416-28. [PMID: 23378025 PMCID: PMC3644142 DOI: 10.1242/jcs.117960] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/19/2012] [Indexed: 12/22/2022] Open
Abstract
Phospholipase D2 (PLD2) is a cell-signaling molecule that bears two activities: a guanine-nucleotide exchange factor (GEF) and a lipase that reside in the PX/PH domains and in two HKD domains, respectively. Upon cell stimulation, the GEF activity yields Rac2-GTP and the lipase activity yields phosphatidic acid (PA). In the present study, we show for the first time that these activities regulate one another. Upon cell stimulation, both GEF and lipase activities are quickly (within ∼3 min) elevated. As soon as it is produced, PA positively feeds back on the GEF and further activates it. Rac2-GTP, on the other hand, is inhibitory to the lipase activity. PLD2 would remain downregulated if it were not for the contribution of the tyrosine kinase Janus kinase 3 (JAK3), which restores lipase action (by phosphorylation at Y415). Conversely, the GEF is inhibited upon phosphorylation by JAK3 and is effectively terminated by this action and by the increasing accumulation of PA at >15 min of cell stimulation. This PA interferes with the ability of the GEF to bind to its substrate (Rac2-GTP). Thus, both temporal inter-regulation and phosphorylation-dependent mechanisms are involved in determining a GEF-lipase switch within the same molecule. Human neutrophils stimulated by interleukin-8 follow a biphasic pattern of GEF and lipase activation that can be explained by such an intramolecular switch. This is the first report of a temporal inter-regulation of two enzymatic activities that reside in the same molecule with profound biological consequences in leukocyte cell migration.
Collapse
Affiliation(s)
| | | | - Julian Gomez-Cambronero
- Department of Biochemistry and Molecular Biology, Wright State University School of Medicine, OH 45435, USA
| |
Collapse
|
45
|
Fox TE, Young MM, Pedersen MM, Han X, Gardner TW, Kester M. Diabetes diminishes phosphatidic acid in the retina: a putative mediator for reduced mTOR signaling and increased neuronal cell death. Invest Ophthalmol Vis Sci 2012; 53:7257-67. [PMID: 22952117 DOI: 10.1167/iovs.11-7626] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
PURPOSE We demonstrated previously that pro-survival insulin receptor, PI3K-Akt, and p70 S6K signaling is diminished in models of diabetic retinopathy. As mammalian target of rapamycin (mTOR), an upstream activator of p70 S6Kinase is, in part, regulated by lipid-derived second messengers, such as phosphatidic acid (PA), we sought to determine if diminished mTOR/p70 S6Kinase signaling in diabetic retinas may reflect diminished PA levels. METHODS Alterations in PA mass from retinas of control and streptozotocin-induced diabetic rats were determined by mass spectrometry. The biochemical and biophysical mechanisms underlying the actions of PA on insulin-activated mTOR/p70 S6Kinase signaling were determined using R28 retinal neuronal cells. RESULTS We demonstrate a significant decrease in PA in R28 retinal neuronal cells exposed to hyperglycemia as well as in streptozotocin-induced diabetic rat retinas. Exogenous PA augmented insulin-induced protection from interleukin-1β-induced apoptosis. Moreover, exogenous PA and insulin cooperatively activated mTOR survival pathways in R28 neuronal cultures. Exogenous PA colocalized with activated mTOR/p70 S6kinase signaling elements within lipid microdomains. The biochemical consequences of this biophysical mechanism is reflected by differential phosphorylation of tuberin at threonine 1462 and serine 1798, respectively, by PA and insulin, which reduce this suppressor of mTOR/S6Kinase signaling within lipid microdomains. CONCLUSIONS These results identify PA-enriched microdomains as a putative lipid-based signaling element responsible for mTOR-dependent retinal neuronal survival. Moreover, diabetic retinal neuronal apoptosis may reflect diminished PA mass. Elevating PA concentrations and restoring mTOR signaling may be an effective therapeutic modality to reduce neuronal cell death in diabetic retinopathy.
Collapse
Affiliation(s)
- Todd E Fox
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033, USA
| | | | | | | | | | | |
Collapse
|
46
|
Hoffman JR, Stout JR, Williams DR, Wells AJ, Fragala MS, Mangine GT, Gonzalez AM, Emerson NS, McCormack WP, Scanlon TC, Purpura M, Jäger R. Efficacy of phosphatidic acid ingestion on lean body mass, muscle thickness and strength gains in resistance-trained men. J Int Soc Sports Nutr 2012; 9:47. [PMID: 23035701 PMCID: PMC3506449 DOI: 10.1186/1550-2783-9-47] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 09/26/2012] [Indexed: 01/02/2023] Open
Abstract
UNLABELLED BACKGROUND Phosphatidic acid (PA) has been reported to activate the mammalian target of rapamycin (mTOR) signaling pathway and is thought to enhance the anabolic effects of resistance training. The purpose of this pilot study was to examine if oral phosphatidic acid administration can enhance strength, muscle thickness and lean tissue accruement during an 8-week resistance training program. METHODS Sixteen resistance-trained men were randomly assigned to a group that either consumed 750 mg of PA (n = 7, 23.1 ± 4.4 y; 176.7 ± 6.7 cm; 86.5 ± 21.2 kg) or a placebo (PL, n = 9, 22.5 ± 2.0 y; 179.8 ± 5.4 cm; 89.4 ± 13.6 kg) group. During each testing session subjects were assessed for strength (one repetition maximum [1-RM] bench press and squat) and body composition. Muscle thickness and pennation angle were also measured in the vastus lateralis of the subject's dominant leg. RESULTS Subjects ingesting PA demonstrated a 12.7% increase in squat strength and a 2.6% increase in LBM, while subjects consuming PL showed a 9.3% improvement in squat strength and a 0.1% change in LBM. Although parametric analysis was unable to demonstrate significant differences, magnitude based inferences indicated that the Δ change in 1-RM squat showed a likely benefit from PA on increasing lower body strength and a very likely benefit for increasing lean body mass (LBM). CONCLUSIONS Results of this study suggest that a combination of a daily 750 mg PA ingestion, combined with a 4-day per week resistance training program for 8-weeks appears to have a likely benefit on strength improvement, and a very likely benefit on lean tissue accruement in young, resistance trained individuals.
Collapse
Affiliation(s)
- Jay R Hoffman
- Human Performance Laboratory, University of Central Florida, Orlando, 32186, FL, USA
| | - Jeffrey R Stout
- Human Performance Laboratory, University of Central Florida, Orlando, 32186, FL, USA
| | - David R Williams
- Human Performance Laboratory, University of Central Florida, Orlando, 32186, FL, USA
| | - Adam J Wells
- Human Performance Laboratory, University of Central Florida, Orlando, 32186, FL, USA
| | - Maren S Fragala
- Human Performance Laboratory, University of Central Florida, Orlando, 32186, FL, USA
| | - Gerald T Mangine
- Human Performance Laboratory, University of Central Florida, Orlando, 32186, FL, USA
| | - Adam M Gonzalez
- Human Performance Laboratory, University of Central Florida, Orlando, 32186, FL, USA
| | - Nadia S Emerson
- Human Performance Laboratory, University of Central Florida, Orlando, 32186, FL, USA
| | - William P McCormack
- Human Performance Laboratory, University of Central Florida, Orlando, 32186, FL, USA
| | - Tyler C Scanlon
- Human Performance Laboratory, University of Central Florida, Orlando, 32186, FL, USA
| | - Martin Purpura
- Increnovo LLC, 2138 E. Lafayette Pl, Milwaukee, 53202, WI, USA
| | - Ralf Jäger
- Increnovo LLC, 2138 E. Lafayette Pl, Milwaukee, 53202, WI, USA
| |
Collapse
|
47
|
Martín R, Cordova C, Nieto ML. Secreted phospholipase A2-IIA-induced a phenotype of activated microglia in BV-2 cells requires epidermal growth factor receptor transactivation and proHB-EGF shedding. J Neuroinflammation 2012; 9:154. [PMID: 22747893 PMCID: PMC3488565 DOI: 10.1186/1742-2094-9-154] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 06/04/2012] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Activation of microglia, the primary component of the innate immune response in the brain, is a hallmark of neuroinflammation in neurodegenerative disorders, including Alzheimer's disease (AD) and other pathological conditions such as stroke or CNS infection. In response to a variety of insults, microglial cells produce high levels of inflammatory cytokines that are often involved in neuronal injury, and play an important role in the recognition, engulfment, and clearance of apoptotic cells and/or invading microbes. Secreted phospholipase A2-IIA (sPLA2-IIA), an enzyme that interacts with cells involved in the systemic immune/inflammatory response, has been found up-regulated in the cerebrospinal fluid and brain of AD patients. However, despite several approaches, its functions in mediating CNS inflammation remain unknown. In the present study, the role of sPLA2-IIA was examined by investigating its direct effects on microglial cells. METHODS Primary and immortalized microglial cells were stimulated by sPLA2-IIA in order to characterize the cytokine-like actions of the phospholipase. The hallmarks of activated microglia analyzed include: mitogenic response, phagocytic capabilities and induction of inflammatory mediators. In addition, we studied several of the potential molecular mechanisms involved in those events. RESULTS The direct exposure of microglial cells to sPLA2-IIA stimulated, in a time- and dose-dependent manner, their phagocytic and proliferative capabilities. sPLA2-IIA also triggered the synthesis of the inflammatory proteins COX-2 and TNFα. In addition, EGFR phosphorylation and shedding of the membrane-anchored heparin-binding EGF-like growth factor (pro-HB-EGF) ectodomain, as well as a rapid activation/phosphorylation of the classical survival proteins ERK, P70S6K and rS6 were induced upon sPLA2-IIA treatment. We further demonstrated that the presence of an EGFR inhibitor (AG1478), a matrix metalloproteinase inhibitor (GM6001), an ADAM inhibitor (TAPI-1), and a HB-EGF neutralizing antibody abrogated the phenotype of activated microglia induced by the sPLA2-IIA. CONCLUSION These results support the hypothesis that sPLA2-IIA may act as a potent modulator of microglial functions through its ability to induce EGFR transactivation and HB-EGF release. Accordingly, pharmacological modulation of EGFR might be a useful tool for treating neuroinflammatory diseases characterized by sPLA2-IIA accumulation.
Collapse
Affiliation(s)
- Rubén Martín
- Instituto de Biología y Genetica Molecular (IBGM), CSIC-UVa, Valladolid, Spain
- ICICOR, Hospital Clínico, Valladolid, Spain
| | - Claudia Cordova
- Instituto de Biología y Genetica Molecular (IBGM), CSIC-UVa, Valladolid, Spain
| | - Maria L Nieto
- Instituto de Biología y Genetica Molecular (IBGM), CSIC-UVa, Valladolid, Spain
| |
Collapse
|
48
|
Jang JH, Lee CS, Hwang D, Ryu SH. Understanding of the roles of phospholipase D and phosphatidic acid through their binding partners. Prog Lipid Res 2011; 51:71-81. [PMID: 22212660 DOI: 10.1016/j.plipres.2011.12.003] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Phospholipase D (PLD) is a phosphatidyl choline (PC)-hydrolyzing enzyme that generates phosphatidic acid (PA), a lipid second messenger that modulates diverse intracellular signaling. Through interactions with signaling molecules, both PLD and PA can mediate a variety of cellular functions, such as, growth/proliferation, vesicle trafficking, cytoskeleton modulation, development, and morphogenesis. Therefore, systemic approaches for investigating PLD networks including interrelationship between PLD and PA and theirs binding partners, such as proteins and lipids, can enhance fundamental knowledge of roles of PLD and PA in diverse biological processes. In this review, we summarize previously reported protein-protein and protein-lipid interactions of PLD and PA and their binding partners. In addition, we describe the functional roles played by PLD and PA in these interactions, and provide PLD network that summarizes these interactions. The PLD network suggests that PLD and PA could act as a decision maker and/or as a coordinator of signal dynamics. This viewpoint provides a turning point for understanding the roles of PLD-PA as a dynamic signaling hub.
Collapse
Affiliation(s)
- Jin-Hyeok Jang
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang, Kyungbook 790-784, South Korea
| | | | | | | |
Collapse
|
49
|
Gomez-Cambronero J. The exquisite regulation of PLD2 by a wealth of interacting proteins: S6K, Grb2, Sos, WASp and Rac2 (and a surprise discovery: PLD2 is a GEF). Cell Signal 2011; 23:1885-95. [PMID: 21740967 PMCID: PMC3204931 DOI: 10.1016/j.cellsig.2011.06.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Accepted: 06/21/2011] [Indexed: 11/28/2022]
Abstract
Phospholipase D (PLD) catalyzes the conversion of the membrane phospholipid phosphatidylcholine to choline and phosphatidic acid (PA). PLD's mission in the cell is two-fold: phospholipid turnover with maintenance of the structural integrity of cellular/intracellular membranes and cell signaling through PA and its metabolites. Precisely, through its product of the reaction, PA, PLD has been implicated in a variety of physiological cellular functions, such as intracellular protein trafficking, cytoskeletal dynamics, chemotaxis of leukocytes and cell proliferation. The catalytic (HKD) and regulatory (PH and PX) domains were studied in detail in the PLD1 isoform, but PLD2 was traditionally studied in lesser detail and much less was known about its regulation. Our laboratory has been focusing on the study of PLD2 regulation in mammalian cells. Over the past few years, we have reported, in regards to the catalytic action of PLD, that PA is a chemoattractant agent that binds to and signals inside the cell through the ribosomal S6 kinases (S6K). Regarding the regulatory domains of PLD2, we have reported the discovery of the PLD2 interaction with Grb2 via Y169 in the PX domain, and further association to Sos, which results in an increase of de novo DNA synthesis and an interaction (also with Grb2) via the adjacent residue Y179, leading to the regulation of cell ruffling, chemotaxis and phagocytosis of leukocytes. We also present the complex regulation by tyrosine phosphorylation by epidermal growth factor receptor (EGF-R), Janus Kinase 3 (JAK3) and Src and the role of phosphatases. Recently, there is evidence supporting a new level of regulation of PLD2 at the PH domain, by the discovery of CRIB domains and a Rac2-PLD2 interaction that leads to a dual (positive and negative) effect on its enzymatic activity. Lastly, we review the surprising finding of PLD2 acting as a GEF. A phospholipase such as PLD that exists already in the cell membrane that acts directly on Rac allows a quick response of the cell without intermediary signaling molecules. This provides only the latest level of PLD2 regulation in a field that promises newer and exciting advances in the next few years.
Collapse
Affiliation(s)
- Julian Gomez-Cambronero
- Department of Biochemistry and Molecular Biology, Wright State University School of Medicine, Dayton, OH 45435, USA.
| |
Collapse
|
50
|
Di Fulvio M, Frondorf K, Henkels KM, Grunwald WC, Cool D, Gomez-Cambronero J. Phospholipase D2 (PLD2) shortens the time required for myeloid leukemic cell differentiation: mechanism of action. J Biol Chem 2011; 287:393-407. [PMID: 22094461 DOI: 10.1074/jbc.m111.259465] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cell differentiation is compromised in acute leukemias. We report that mammalian target of rapamycin (mTOR) and S6 kinase (S6K) are highly expressed in the undifferentiated promyelomonocytic leukemic HL-60 cell line, whereas PLD2 expression is minimal. The expression ratio of PLD2 to mTOR (or to S6K) is gradually inverted upon in vitro induction of differentiation toward the neutrophilic phenotype. We present three ways that profoundly affect the kinetics of differentiation as follows: (i) simultaneous overexpression of mTOR (or S6K), (ii) silencing of mTOR via dsRNA-mediated interference or inhibition with rapamycin, and (iii) PLD2 overexpression. The last two methods shortened the time required for differentiation. By determining how PLD2 participates in cell differentiation, we found that PLD2 interacts with and activates the oncogene Fes/Fps, a protein-tyrosine kinase known to be involved in myeloid cell development. Fes activity is elevated with PLD2 overexpression, phosphatidic acid or phosphatidylinositol bisphosphate. Co-immunoprecipitation indicates a close PLD2-Fes physical interaction that is negated by a Fes-R483K mutant that incapacitates its Src homology 2 domain. All these suggest for the first time the following mechanism: mTOR/S6K down-regulation→PLD2 overexpression→PLD2/Fes association→phosphatidic acid-led activation of Fes kinase→granulocytic differentiation. Differentiation shortening could have a clinical impact on reducing the time of return to normalcy of the white cell counts after chemotherapy in patients with acute promyelocytic leukemia.
Collapse
Affiliation(s)
- Mauricio Di Fulvio
- Department of Biochemistry and Molecular Biology, Wright State University School Medicine, Dayton, Ohio, 45435
| | - Kathleen Frondorf
- Department of Biochemistry and Molecular Biology, Wright State University School Medicine, Dayton, Ohio, 45435
| | - Karen M Henkels
- Department of Biochemistry and Molecular Biology, Wright State University School Medicine, Dayton, Ohio, 45435
| | - William C Grunwald
- Department of Pharmacology and Toxicology, Wright State University School Medicine, Dayton, Ohio 45435
| | - David Cool
- Department of Pharmacology and Toxicology, Wright State University School Medicine, Dayton, Ohio 45435
| | - Julian Gomez-Cambronero
- Department of Biochemistry and Molecular Biology, Wright State University School Medicine, Dayton, Ohio, 45435.
| |
Collapse
|