Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 102
Filter
Add more filters










Publication year range
1.
EMBO J ; 41(17): e110698, 2022 09 01.
Article in English | MEDLINE | ID: mdl-35844135

ABSTRACT

The Arf GTPase family is involved in a wide range of cellular regulation including membrane trafficking and organelle-structure assembly. Here, we have generated a proximity interaction network for the Arf family using the miniTurboID approach combined with TMT-based quantitative mass spectrometry. Our interactome confirmed known interactions and identified many novel interactors that provide leads for defining Arf pathway cell biological functions. We explored the unexpected finding that phospholipase D1 (PLD1) preferentially interacts with two closely related but poorly studied Arf family GTPases, ARL11 and ARL14, showing that PLD1 is activated by ARL11/14 and may recruit these GTPases to membrane vesicles, and that PLD1 and ARL11 collaborate to promote macrophage phagocytosis. Moreover, ARL5A and ARL5B were found to interact with and recruit phosphatidylinositol 4-kinase beta (PI4KB) at trans-Golgi, thus promoting PI4KB's function in PI4P synthesis and protein secretion.


Subject(s)
1-Phosphatidylinositol 4-Kinase , Phospholipase D , GTP Phosphohydrolases/metabolism , Golgi Apparatus/metabolism , Phospholipase D/chemistry , Phospholipase D/genetics , Phospholipase D/metabolism
2.
Adv Biol Regul ; 79: 100783, 2021 01.
Article in English | MEDLINE | ID: mdl-33495125

ABSTRACT

Mammalian phospholipase D (PLD) generates phosphatidic acid, a dynamic lipid secondary messenger involved with a broad spectrum of cellular functions including but not limited to metabolism, migration, and exocytosis. As a promising pharmaceutical target, the biochemical properties of PLD have been well characterized. This has led to the recent crystal structures of human PLD1 and PLD2, the development of PLD specific pharmacological inhibitors, and the identification of cellular regulators of PLD. In this review, we discuss the PLD1 and PLD2 structures, PLD inhibition by small molecules, and the regulation of PLD activity by effector proteins and lipids.


Subject(s)
Phospholipase D/chemistry , Phospholipase D/metabolism , Animals , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/metabolism , Humans , Phosphatidic Acids/metabolism , Phospholipase D/antagonists & inhibitors , Phospholipase D/genetics , Signal Transduction
3.
Adv Exp Med Biol ; 1259: 77-87, 2020.
Article in English | MEDLINE | ID: mdl-32578172

ABSTRACT

The lipid-modifying signal transduction enzyme phospholipase D (PLD) has been proposed to have roles in oncogenic processes for well-on 30 years, with most of the early literature focused on potential functions for PLD in the biology of the tumor cells themselves. While such roles remain under investigation, evidence has also now been generated to support additional roles for PLD, in particular PLD1, in the tumor microenvironment, including effects on neoangiogenesis, the supply of nutrients, interactions of platelets with circulating cancer cells, the response of the immune system, and exosome biology. Here, we review these lines of investigation, accompanied by a discussion of the limitations of the existing studies and some cautionary notes regarding the study and interpretation of PLD function using model systems.


Subject(s)
Neoplasms/metabolism , Phospholipase D/metabolism , Tumor Microenvironment , Animals , Humans , Neoplasms/blood supply , Neovascularization, Pathologic , Signal Transduction
4.
Nat Chem Biol ; 16(4): 400-407, 2020 04.
Article in English | MEDLINE | ID: mdl-32198492

ABSTRACT

The signal transduction enzyme phospholipase D1 (PLD1) hydrolyzes phosphatidylcholine to generate the lipid second-messenger phosphatidic acid, which plays roles in disease processes such as thrombosis and cancer. PLD1 is directly and synergistically regulated by protein kinase C, Arf and Rho GTPases, and the membrane lipid phosphatidylinositol-4,5-bisphosphate (PIP2). Here, we present a 1.8 Å-resolution crystal structure of the human PLD1 catalytic domain, which is characterized by a globular fold with a funnel-shaped hydrophobic cavity leading to the active site. Adjacent is a PIP2-binding polybasic pocket at the membrane interface that is essential for activity. The C terminus folds into and contributes part of the catalytic pocket, which harbors a phosphohistidine that mimics an intermediate stage of the catalytic cycle. Mapping of PLD1 mutations that disrupt RhoA activation identifies the RhoA-PLD1 binding interface. This structure sheds light on PLD1 regulation by lipid and protein effectors, enabling rationale inhibitor design for this well-studied therapeutic target.


Subject(s)
Phosphatidylinositol 4,5-Diphosphate/metabolism , Phospholipase D/metabolism , Phospholipase D/ultrastructure , rhoA GTP-Binding Protein/metabolism , Animals , COS Cells , Catalysis , Catalytic Domain , Chlorocebus aethiops , Humans , Membrane Lipids , Phosphatidylcholines , Protein Binding , Protein Kinase C/metabolism , Second Messenger Systems , Signal Transduction/drug effects
5.
Handb Exp Pharmacol ; 259: 79-88, 2020.
Article in English | MEDLINE | ID: mdl-31541323

ABSTRACT

Functions for phospholipase D1 and D2 (PLD1 and PLD2), the canonical isoforms of the PLD superfamily in mammals, have been explored using cell biological and animal disease models for two decades. PLD1 and PLD2, which are activated as a consequence of extracellular signaling events and generate the second messenger signaling lipid phosphatidic acid (PA), have been reported to play roles in settings ranging from platelet activation to the response to cardiac ischemia, viral infection, neurodegenerative disease, and cancer. Of these, the most tractable as therapeutic targets may be thrombotic disease and cancer, as will be discussed here in the context of ongoing efforts to develop small molecule PLD inhibitors.


Subject(s)
Enzyme Inhibitors/pharmacology , Neoplasms/enzymology , Phospholipase D/antagonists & inhibitors , Thrombosis/enzymology , Animals , Humans , Isoenzymes/antagonists & inhibitors , Signal Transduction
7.
Biomed Opt Express ; 10(1): 29-49, 2019 Jan 01.
Article in English | MEDLINE | ID: mdl-30775081

ABSTRACT

Visualizing diverse anatomical and functional traits that span many spatial scales with high spatio-temporal resolution provides insights into the fundamentals of living organisms. Light-field microscopy (LFM) has recently emerged as a scanning-free, scalable method that allows for high-speed, volumetric functional brain imaging. Given those promising applications at the tissue level, at its other extreme, this highly-scalable approach holds great potential for observing structures and dynamics in single-cell specimens. However, the challenge remains for current LFM to achieve a subcellular level, near-diffraction-limited 3D spatial resolution. Here, we report high-resolution LFM (HR-LFM) for live-cell imaging with a resolution of 300-700 nm in all three dimensions, an imaging depth of several micrometers, and a volume acquisition time of milliseconds. We demonstrate the technique by imaging various cellular dynamics and structures and tracking single particles. The method may advance LFM as a particularly useful tool for understanding biological systems at multiple spatio-temporal levels.

8.
J Leukoc Biol ; 103(5): 867-883, 2018 05.
Article in English | MEDLINE | ID: mdl-29656494

ABSTRACT

The uptake of cholesterol carried by low-density lipoprotein (LDL) is tightly controlled in the body. Macrophages are not well suited to counteract the cellular consequences of excess cholesterol leading to their transformation into "foam cells," an early step in vascular plaque formation. We have uncovered and characterized a novel mechanism involving phospholipase D (PLD) in foam cell formation. Utilizing bone marrow-derived macrophages from genetically PLD deficient mice, we demonstrate that PLD2 (but not PLD1)-null macrophages cannot fully phagocytose aggregated oxidized LDL (Agg-Ox-LDL), which was phenocopied with a PLD2-selective inhibitor. We also report a role for PLD2 in coupling Agg-oxLDL phagocytosis with WASP, Grb2, and Actin. Further, the clearance of LDL particles is mediated by both CD36 and PLD2, via mutual dependence on each other. In the absence of PLD2, CD36 does not engage in Agg-Ox-LDL removal and when CD36 is blocked, PLD2 cannot form protein-protein heterocomplexes with WASP or Actin. These results translated into humans using a GEO database of microarray expression data from atheroma plaques versus normal adjacent carotid tissue and observed higher values for NFkB, PLD2 (but not PLD1), WASP, and Grb2 in the atheroma plaques. Human atherectomy specimens confirmed high presence of PLD2 (mRNA and protein) as well as phospho-WASP in diseased arteries. Thus, PLD2 interacts in macrophages with Actin, Grb2, and WASP during phagocytosis of Agg-Ox-LDL in the presence of CD36 during their transformation into "foam cells." Thus, this study provides new molecular targets to counteract vascular plaque formation and atherogenesis.


Subject(s)
CD36 Antigens/metabolism , Foam Cells/pathology , Lipoproteins, LDL/metabolism , Phagocytosis , Phospholipase D/physiology , Plaque, Atherosclerotic/pathology , Animals , CD36 Antigens/genetics , Cells, Cultured , Cholesterol/metabolism , Female , Foam Cells/metabolism , GRB2 Adaptor Protein/genetics , GRB2 Adaptor Protein/metabolism , Humans , Macrophages/metabolism , Macrophages/pathology , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Plaque, Atherosclerotic/genetics , Plaque, Atherosclerotic/metabolism , Wiskott-Aldrich Syndrome Protein/genetics , Wiskott-Aldrich Syndrome Protein/metabolism
9.
Adv Biol Regul ; 67: 134-140, 2018 01.
Article in English | MEDLINE | ID: mdl-29154090

ABSTRACT

Phospholipase D (PLD) activity has been proposed to facilitate multiple steps in cancer progression including growth, metabolism, angiogenesis, and mobility. The canonical enzymes PLD1 and PLD2 enact their diverse effects through hydrolyzing the membrane lipid phosphatidylcholine to generate the second messenger and signaling lipid phosphatidic acid (PA). However, the widespread expression of PLD1 and PLD2 in normal tissues and the additional distinct enzymatic mechanisms through which PA can be generated have produced uncertainty regarding the optimal settings in which PLD inhibition might ameliorate cancer. Recent studies in mouse model systems have demonstrated that inhibition or elimination of PLD activity reduces tumor growth and metastasis. One mechanism proposed for this outcome involves proliferative signaling mediated by receptor tyrosine kinases (RTK) and G protein-coupled receptors (GPCR), which is attenuated when downstream PLD signal propagation is suppressed. The reduced proliferative signaling has been reported to be compounded by dysfunctional energetic metabolism in the tumor cells under conditions of nutrient deprivation. Moreover, cancer cells lacking PLD activity display inefficiencies across multiple steps of the metastatic cascade, limiting the tumor's lethal spread. Using PLD isoform knockout mice, recent studies have reported on the net effects of inhibition and ablation in multiple cancer models through examining the role of PLD in the non-tumor cells comprising the stroma and microenvironment. The promising results of such in vivo studies, combined with the apparent low toxicity of highly-specific and potent inhibitors, highlights PLD as an attractive target for therapeutic inhibition in cancer. We discuss here the array of anti-tumor effects produced by PLD inhibition and ablation in cancer models with a focus on animal studies.


Subject(s)
Neoplasm Proteins/metabolism , Neoplasms, Experimental/enzymology , Phospholipase D/metabolism , Signal Transduction , Animals , Humans , Isoenzymes/genetics , Isoenzymes/metabolism , Mice , Neoplasm Proteins/genetics , Neoplasms, Experimental/genetics , Neoplasms, Experimental/pathology , Phosphatidic Acids/genetics , Phosphatidic Acids/metabolism , Phospholipase D/genetics
10.
Sci Rep ; 7(1): 9112, 2017 08 22.
Article in English | MEDLINE | ID: mdl-28831159

ABSTRACT

The Phospholipase D (PLD) superfamily is linked to neurological disease, cancer, and fertility, and a recent report correlated a potential loss-of-function PLD2 polymorphism with hypotension. Surprisingly, PLD2 -/- mice exhibit elevated blood pressure accompanied by associated changes in cardiac performance and molecular markers, but do not have findings consistent with the metabolic syndrome. Instead, expression of endothelial nitric oxide synthase (eNOS), which generates the potent vasodilator nitric oxide (NO), is decreased. An eNOS inhibitor phenocopied PLD2 loss and had no further effect on PLD2 -/- mice, confirming the functional relationship. Using a human endothelial cell line, PLD2 loss of function was shown to lower intracellular free cholesterol, causing upregulation of HMG Co-A reductase, the rate-limiting enzyme in cholesterol synthesis. HMG Co-A reductase negatively regulates eNOS, and the PLD2-deficiency phenotype of decreased eNOS expression and activity could be rescued by cholesterol supplementation and HMG Co-A reductase inhibition. Together, these findings identify a novel pathway through which the lipid signaling enzyme PLD2 regulates blood pressure, creating implications for on-going therapeutic development of PLD small molecule inhibitors. Finally, we show that the human PLD2 polymorphism does not trigger eNOS loss, but rather creates another effect, suggesting altered functioning for the allele.


Subject(s)
Blood Pressure/genetics , Nitric Oxide Synthase Type III/metabolism , Phospholipase D/deficiency , Signal Transduction , Animals , Cholesterol/metabolism , Gene Expression , Gene Expression Regulation , Human Umbilical Vein Endothelial Cells/metabolism , Humans , Hydroxymethylglutaryl CoA Reductases/genetics , Hyperlipidemias/etiology , Hyperlipidemias/metabolism , Male , Mice , Mice, Knockout , Mutation , Nitric Oxide/biosynthesis , Nitric Oxide Synthase Type III/genetics , Obesity/etiology , Obesity/metabolism
11.
Mol Cell ; 63(6): 1034-43, 2016 09 15.
Article in English | MEDLINE | ID: mdl-27635761

ABSTRACT

Mitochondria divide to control their size, distribution, turnover, and function. Dynamin-related protein 1 (Drp1) is a critical mechanochemical GTPase that drives constriction during mitochondrial division. It is generally believed that mitochondrial division is regulated during recruitment of Drp1 to mitochondria and its oligomerization into a division apparatus. Here, we report an unforeseen mechanism that regulates mitochondrial division by coincident interactions of Drp1 with the head group and acyl chains of phospholipids. Drp1 recognizes the head group of phosphatidic acid (PA) and two saturated acyl chains of another phospholipid by penetrating into the hydrophobic core of the membrane. The dual phospholipid interactions restrain Drp1 via inhibition of oligomerization-stimulated GTP hydrolysis that promotes membrane constriction. Moreover, a PA-producing phospholipase, MitoPLD, binds Drp1, creating a PA-rich microenvironment in the vicinity of a division apparatus. Thus, PA controls the activation of Drp1 after the formation of the division apparatus.


Subject(s)
Dynamins/genetics , Mitochondria/metabolism , Mitochondrial Dynamics/genetics , Mitochondrial Proteins/genetics , Phosphatidic Acids/metabolism , Phospholipase D/genetics , Testis/metabolism , Animals , Binding Sites , Dynamins/metabolism , Fibroblasts/metabolism , Fibroblasts/ultrastructure , Gene Expression Regulation , Guanosine Triphosphate/metabolism , Male , Mice , Mitochondria/ultrastructure , Mitochondrial Membranes/metabolism , Mitochondrial Membranes/ultrastructure , Mitochondrial Proteins/metabolism , Phospholipase D/metabolism , Protein Binding , Signal Transduction , Stearoyl-CoA Desaturase/genetics , Stearoyl-CoA Desaturase/metabolism , Testis/ultrastructure
12.
Mol Cell ; 63(6): 1021-33, 2016 09 15.
Article in English | MEDLINE | ID: mdl-27618486

ABSTRACT

Twist has been shown to cause treatment failure, cancer progression, and cancer-related death. However, strategies that directly target Twist are not yet conceivable. Here we reveal that K63-linked ubiquitination is a crucial regulatory mechanism for Twist activation. Through an E3 ligase screen and biochemical studies, we unexpectedly identified that RNF8 functions as a direct Twist activator by triggering K63-linked ubiquitination of Twist. RNF8-promoted Twist ubiquitination is required for Twist localization to the nucleus for subsequent EMT and CSC functions, thereby conferring chemoresistance. Our histological analyses showed that RNF8 expression is upregulated and correlated with disease progression, EMT features, and poor patient survival in breast cancer. Moreover, RNF8 regulates cancer cell migration and invasion and cancer metastasis, recapitulating the effect of Twist. Together, our findings reveal a previously unrecognized tumor-promoting function of RNF8 and provide evidence that targeting RNF8 is an appealing strategy to tackle tumor aggressiveness and treatment resistance.


Subject(s)
Breast Neoplasms/genetics , DNA-Binding Proteins/genetics , Drug Resistance, Neoplasm/genetics , Gene Expression Regulation, Neoplastic , Neoplastic Stem Cells/metabolism , Nuclear Proteins/genetics , Twist-Related Protein 1/genetics , Animals , Antineoplastic Agents/therapeutic use , Breast Neoplasms/drug therapy , Breast Neoplasms/mortality , Breast Neoplasms/pathology , Cell Line, Tumor , DNA Damage , DNA-Binding Proteins/antagonists & inhibitors , DNA-Binding Proteins/metabolism , Disease Progression , Epithelial-Mesenchymal Transition , Female , Genes, Reporter , Humans , Luciferases/genetics , Luciferases/metabolism , Lysine/metabolism , MCF-7 Cells , Mice, Nude , Neoplasm Invasiveness , Neoplasm Transplantation , Neoplastic Stem Cells/drug effects , Neoplastic Stem Cells/pathology , Nuclear Proteins/antagonists & inhibitors , Nuclear Proteins/metabolism , RNA, Small Interfering/genetics , RNA, Small Interfering/metabolism , Signal Transduction , Survival Analysis , Twist-Related Protein 1/antagonists & inhibitors , Twist-Related Protein 1/metabolism , Ubiquitin-Protein Ligases , Ubiquitination
13.
Neuron ; 88(5): 941-956, 2015 Dec 02.
Article in English | MEDLINE | ID: mdl-26606998

ABSTRACT

NG2-expressing glia (NG2 glia) are a uniformly distributed and mitotically active pool of cells in the central nervous system (CNS). In addition to serving as progenitors of myelinating oligodendrocytes, NG2 glia might also fulfill physiological roles in CNS homeostasis, although the mechanistic nature of such roles remains unclear. Here, we report that ablation of NG2 glia in the prefrontal cortex (PFC) of the adult brain causes deficits in excitatory glutamatergic neurotransmission and astrocytic extracellular glutamate uptake and induces depressive-like behaviors in mice. We show in parallel that chronic social stress causes NG2 glia density to decrease in areas critical to Major Depressive Disorder (MDD) pathophysiology at the time of symptom emergence in stress-susceptible mice. Finally, we demonstrate that loss of NG2 glial secretion of fibroblast growth factor 2 (FGF2) suffices to induce the same behavioral deficits. Our findings outline a pathway and role for NG2 glia in CNS homeostasis and mood disorders.


Subject(s)
Antigens/metabolism , Depression/pathology , Fibroblast Growth Factor 2/metabolism , Neuroglia/metabolism , Prefrontal Cortex/pathology , Proteoglycans/metabolism , Stress, Psychological/physiopathology , Amino Acid Transport System X-AG/genetics , Amino Acid Transport System X-AG/metabolism , Animals , Antigens/genetics , Depression/etiology , Diphtheria Toxin/administration & dosage , Disease Models, Animal , Down-Regulation/genetics , Exploratory Behavior/physiology , Fibroblast Growth Factor 2/genetics , Heparin-binding EGF-like Growth Factor/genetics , Humans , Membrane Potentials/drug effects , Membrane Potentials/genetics , Mice , Mice, Inbred C57BL , Mice, Transgenic , Neurons/drug effects , Neurons/metabolism , Phosphopyruvate Hydratase/metabolism , Protein Transport/drug effects , Protein Transport/genetics , Proteoglycans/genetics , Receptors, Glutamate/genetics , Receptors, Glutamate/metabolism , Signal Transduction/drug effects , Signal Transduction/genetics , Synaptic Transmission/drug effects , Synaptic Transmission/genetics
14.
J Lipid Res ; 56(12): 2229-37, 2015 Dec.
Article in English | MEDLINE | ID: mdl-25926691

ABSTRACT

Individual members of the mammalian phospholipase D (PLD) superfamily undertake roles that extend from generating the second messenger signaling lipid, phosphatidic acid, through hydrolysis of the membrane phospholipid, phosphatidylcholine, to functioning as an endonuclease to generate small RNAs and facilitating membrane vesicle trafficking through seemingly nonenzymatic mechanisms. With recent advances in genome-wide association studies, RNA interference screens, next-generation sequencing approaches, and phenotypic analyses of knockout mice, roles for PLD family members are being uncovered in autoimmune, infectious neurodegenerative, and cardiovascular disease, as well as in cancer. Some of these disease settings pose opportunities for small molecule inhibitory therapeutics, which are currently in development.


Subject(s)
Phospholipase D/metabolism , Animals , Mice , Neoplasms/genetics , Neoplasms/metabolism , Phosphatidic Acids/metabolism , Phospholipase D/genetics , Signal Transduction/genetics , Signal Transduction/physiology
15.
J Clin Invest ; 125(3): 1347-61, 2015 Mar 02.
Article in English | MEDLINE | ID: mdl-25689250

ABSTRACT

Maintenance of mitochondrial structure and function is critical for preventing podocyte apoptosis and eventual glomerulosclerosis in the kidney; however, the transcription factors that regulate mitochondrial function in podocyte injury remain to be identified. Here, we identified Krüppel-like factor 6 (KLF6), a zinc finger domain transcription factor, as an essential regulator of mitochondrial function in podocyte apoptosis. We observed that podocyte-specific deletion of Klf6 increased the susceptibility of a resistant mouse strain to adriamycin-induced (ADR-induced) focal segmental glomerulosclerosis (FSGS). KLF6 expression was induced early in response to ADR in mice and cultured human podocytes, and prevented mitochondrial dysfunction and activation of intrinsic apoptotic pathways in these podocytes. Promoter analysis and chromatin immunoprecipitation studies revealed that putative KLF6 transcriptional binding sites are present in the promoter of the mitochondrial cytochrome c oxidase assembly gene (SCO2), which is critical for preventing cytochrome c release and activation of the intrinsic apoptotic pathway. Additionally, KLF6 expression was reduced in podocytes from HIV-1 transgenic mice as well as in renal biopsies from patients with HIV-associated nephropathy (HIVAN) and FSGS. Together, these findings indicate that KLF6-dependent regulation of the cytochrome c oxidase assembly gene is critical for maintaining mitochondrial function and preventing podocyte apoptosis.


Subject(s)
Glomerulosclerosis, Focal Segmental/metabolism , HIV Infections/complications , Kidney/metabolism , Kruppel-Like Transcription Factors/physiology , Mitochondria/physiology , Proto-Oncogene Proteins/physiology , Animals , Apoptosis , Binding Sites , Cells, Cultured , Electron Transport Complex IV/genetics , Electron Transport Complex IV/metabolism , Female , Glomerulosclerosis, Focal Segmental/pathology , Glomerulosclerosis, Focal Segmental/virology , HIV Infections/metabolism , HIV-1/physiology , Humans , Kidney/pathology , Kruppel-Like Factor 6 , Male , Mice, Inbred C57BL , Mice, Transgenic , Molecular Chaperones , Podocytes/physiology , Promoter Regions, Genetic
16.
Trends Pharmacol Sci ; 36(3): 137-44, 2015 Mar.
Article in English | MEDLINE | ID: mdl-25661257

ABSTRACT

The phospholipase D (PLD) lipid-signaling enzyme superfamily has long been studied for its roles in cell communication and a wide range of cell biological processes. With the advent of loss-of-function genetic mouse models that have revealed that PLD1 and PLD2 ablation is overtly tolerable, small-molecule PLD1/2 inhibitors that do not cause unacceptable clinical toxicity, a PLD2 polymorphism that has been linked to altered physiology, and growing delineation of processes that are subtly altered in mice lacking PLD1/2 activity, the stage is being set for assessment of PLD1/2 inhibition for therapeutic purposes. Based on findings to date, PLD1/2 inhibition may be of more utility in acute rather than chronic settings, although this generalization will depend on the specific risks and benefits in each disease setting.


Subject(s)
Phospholipase D/antagonists & inhibitors , Alzheimer Disease/drug therapy , Animals , Humans , Hypertension/drug therapy , Influenza, Human/drug therapy , Isoenzymes/antagonists & inhibitors , Isoenzymes/metabolism , Multiple Sclerosis/drug therapy , Neoplasms/drug therapy , Phospholipase D/metabolism , Thrombosis/drug therapy
17.
J Mol Med (Berl) ; 93(3): 263-9, 2015 Mar.
Article in English | MEDLINE | ID: mdl-25471483

ABSTRACT

Clinically important links have been established between mitochondrial function and cardiac physiology and disease in the context of signaling mechanisms, energy production, and muscle cell development. The proteins and processes that drive mitochondrial fusion and fission are now known to have emergent functions in intracellular calcium homeostasis, apoptosis, vascular smooth muscle cell proliferation, myofibril organization, and Notch-driven cell differentiation, all key issues in cardiac disease. Moreover, decreasing fission may confer protection against ischemic heart disease, particularly in the setting of obesity, diabetes, and heart failure. The importance of lipids in controlling mitochondrial fission and fusion is increasingly becoming appreciated. Roles for the bulk and signaling lipids cardiolipin, phosphatidylethanolamine, phosphatidic acid, diacylglycerol, and lysophosphatidic acid and the enzymes that synthesize or metabolize them in the control of mitochondrial shape and function are reviewed here. A number of diseases have been linked to loss-of-function alleles for a subset of the enzymes, emphasizing the importance of the lipid environment in this context.


Subject(s)
Membrane Lipids/physiology , Mitochondrial Dynamics , Animals , Cardiolipins/metabolism , Humans , Mitochondria, Heart/physiology
18.
Mol Biol Cell ; 26(3): 506-17, 2015 Feb 01.
Article in English | MEDLINE | ID: mdl-25428992

ABSTRACT

Myoblast differentiation and fusion is a well-orchestrated multistep process that is essential for skeletal muscle development and regeneration. Phospholipase D1 (PLD1) has been implicated in the initiation of myoblast differentiation in vitro. However, whether PLD1 plays additional roles in myoblast fusion and exerts a function in myogenesis in vivo remains unknown. Here we show that PLD1 expression is up-regulated in myogenic cells during muscle regeneration after cardiotoxin injury and that genetic ablation of PLD1 results in delayed myofiber regeneration. Myoblasts derived from PLD1-null mice or treated with PLD1-specific inhibitor are unable to form mature myotubes, indicating defects in second-phase myoblast fusion. Concomitantly, the PLD1 product phosphatidic acid is transiently detected on the plasma membrane of differentiating myocytes, and its production is inhibited by PLD1 knockdown. Exogenous lysophosphatidylcholine, a key membrane lipid for fusion pore formation, partially rescues fusion defect resulting from PLD1 inhibition. Thus these studies demonstrate a role for PLD1 in myoblast fusion during myogenesis in which PLD1 facilitates the fusion of mononuclear myocytes with nascent myotubes.


Subject(s)
Muscle Development , Muscle, Skeletal/growth & development , Muscle, Skeletal/physiology , Myoblasts, Skeletal/physiology , Phospholipase D/genetics , Regeneration , Animals , Cell Differentiation , Cell Fusion , Cobra Cardiotoxin Proteins/toxicity , Gene Expression Regulation , Mice , Mice, Knockout , Muscle, Skeletal/drug effects , Muscle, Skeletal/enzymology , Myoblasts, Skeletal/enzymology , Phospholipase D/physiology , Up-Regulation
19.
J Invest Dermatol ; 135(2): 499-507, 2015 Feb.
Article in English | MEDLINE | ID: mdl-25233074

ABSTRACT

Aquaporin-3 (AQP3) is a water and glycerol channel expressed in epidermal keratinocytes. Despite many studies, controversy remains about the role of AQP3 in keratinocyte differentiation. Previously, our laboratory has shown co-localization of AQP3 and phospholipase D2 (PLD2) in caveolin-rich membrane microdomains. We hypothesized that AQP3 transports glycerol and "funnels" this primary alcohol to PLD2 to form a pro-differentiative signal, such that the action of AQP3 to induce differentiation should require PLD2. To test this idea, we re-expressed AQP3 in mouse keratinocytes derived from AQP3-knockout mice. The re-expression of AQP3, which increased [3H]glycerol uptake, also induced mRNA and protein expression of epidermal differentiation markers such as keratin 1, keratin 10, and loricrin, with or without the induction of differentiation by an elevated extracellular calcium concentration. Re-expression of AQP3 had no effect on the expression of the proliferation markers keratin 5 and cyclin D1. Furthermore, a selective inhibitor of PLD2, CAY10594, and a lipase-dead (LD) PLD2 mutant, but not a LD PLD1 mutant, significantly inhibited AQP3 re-expression-induced differentiation marker expression with calcium elevation, suggesting a role for PLD2 in this process. Thus, our results indicate that AQP3 has a pro-differentiative role in epidermal keratinocytes and that PLD2 activity is necessary for this effect.


Subject(s)
Aquaporin 3/physiology , Cell Differentiation , Keratinocytes/cytology , Phospholipase D/physiology , Animals , Cell Proliferation , Cells, Cultured , Mice , Mice, Knockout , Phospholipase D/antagonists & inhibitors
20.
Nat Commun ; 5: 4744, 2014 Aug 21.
Article in English | MEDLINE | ID: mdl-25144208

ABSTRACT

The small G protein ADP-ribosylation factor 6 (Arf6) plays important roles in a wide variety of membrane dynamics-based cellular events such as neurite outgrowth and spine formation in vitro. However, little is known about physiological function of Arf6 in vivo. Here we generate conditional knockout mice lacking Arf6 in neurons, oligodendrocytes, or both cell lineages, and unexpectedly find that Arf6 expression in neurons, but not in oligodendrocytes, is crucial for oligodendrocyte myelination in the hippocampal fimbria and the corpus callosum during development, and that this is through the regulation of secretion of fibroblast growth factor-2, a guidance factor for migration of oligodendrocyte precursor cells (OPCs). These results suggest that Arf6 in neurons plays an important role in OPC migration through regulation of FGF-2 secretion during neuronal development.


Subject(s)
ADP-Ribosylation Factors/metabolism , Fibroblast Growth Factor 2/metabolism , Oligodendroglia/physiology , ADP-Ribosylation Factor 6 , ADP-Ribosylation Factors/genetics , Animals , Axons/physiology , Cell Movement , Hippocampus/cytology , Hippocampus/metabolism , Mice, Inbred C57BL , Mice, Knockout , Mice, Transgenic , Myelin Sheath/metabolism , Neurons , Oligodendroglia/cytology
SELECTION OF CITATIONS
SEARCH DETAIL
...