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Journal of Oleo Science 2021Muscle atrophy refers to skeletal muscle loss and dysfunction that affects glucose and lipid metabolism. Moreover, muscle atrophy is manifested in cancer, diabetes, and...
Muscle atrophy refers to skeletal muscle loss and dysfunction that affects glucose and lipid metabolism. Moreover, muscle atrophy is manifested in cancer, diabetes, and obesity. In this study, we focused on lipid metabolism during muscle atrophy. We observed that the gastrocnemius muscle was associated with significant atrophy with 8 days of immobilization of hind limb joints and that muscle atrophy occurred regardless of the muscle fiber type. Further, we performed lipid analyses using thin layer chromatography, liquid chromatography-mass spectrometry, and mass spectrometry imaging. Total amounts of triacylglycerol, phosphatidylserine, and sphingomyelin were found to be increased in the immobilized muscle. Additionally, we found that specific molecular species of phosphatidylserine, phosphatidylcholine, and sphingomyelin were increased by immobilization. Furthermore, the expression of adipose triglyceride lipase and the activity of cyclooxygenase-2 were significantly reduced by atrophy. From these results, it was revealed that lipid accumulation and metabolic changes in specific fatty acids occur during disuse muscle atrophy. The present study holds implications in validating preventive treatment strategies for muscle atrophy.
Topics: Animals; Chromatography, Liquid; Chromatography, Thin Layer; Cyclooxygenase 2; Lipase; Male; Mass Spectrometry; Muscle, Skeletal; Muscular Atrophy; Phosphatidylcholines; Phosphatidylserines; Rats, Sprague-Dawley; Restraint, Physical; Sphingomyelins; Triglycerides; Rats
PubMed: 34193670
DOI: 10.5650/jos.ess21045 -
Journal of Biochemistry Apr 2003In mammalian cells, phosphatidylserine (PtdSer) is synthesized through the action of the endoplasmic reticulum enzymes, PtdSer synthase 1 and 2, and the decarboxylation... (Review)
Review
In mammalian cells, phosphatidylserine (PtdSer) is synthesized through the action of the endoplasmic reticulum enzymes, PtdSer synthase 1 and 2, and the decarboxylation of PtdSer accounts for the majority of phosphatidylethanolamine (PtdEtn) synthesis. PtdSer decarboxylation for PtdEtn formation occurs in the mitochondria. In addition, the transport of PtdSer from the endoplasmic reticulum to the mitochondria is probably a rate limiting step for PtdEtn synthesis through the decarboxylation pathway. Therefore, the regulation of PtdSer synthesis and its intracellular transport appear to be essential events for the maintenance of normal cellular PtdSer and PtdEtn levels. Here we describe the current understanding of the regulation of PtdSer biosynthesis and the transport of PtdSer from the ER to the mitochondria in mammalian cells.
Topics: Animals; Biological Transport; CHO Cells; Cricetinae; Cricetulus; Decarboxylation; Endoplasmic Reticulum; Intracellular Membranes; Mitochondria; Mutation; Nitrogenous Group Transferases; Phosphatidylcholines; Phosphatidylethanolamines; Phosphatidylserines
PubMed: 12761285
DOI: 10.1093/jb/mvg052 -
FEBS Letters Jul 2000Active maintenance of membrane phospholipid asymmetry is universal in normal cell membranes and its disruption with subsequent externalization of phosphatidylserine is a... (Review)
Review
Active maintenance of membrane phospholipid asymmetry is universal in normal cell membranes and its disruption with subsequent externalization of phosphatidylserine is a hallmark of apoptosis. Externalized phosphatidylserine appears to serve as an important signal for targeting recognition and elimination of apoptotic cells by macrophages, however, the molecular mechanisms responsible for phosphatidylserine translocation during apoptosis remain unresolved. Studies have focused on the function of aminophospholipid translocase and phospholipid scramblase as mediators of this process. Here we present evidence that unique oxidative events, represented by selective oxidation of phosphatidylserine, occur during apoptosis that could promote phosphatidylserine externalization. We speculate that selective phosphatidylserine oxidation could affect phosphatidylserine recognition by aminophospholipid translocase and/or directly result in enzyme inhibition. The potential interactions between the anionic phospholipid phosphatidylserine and the redox-active cationic protein effector of apoptosis, cytochrome c, are presented as a potential mechanism to account for selective oxidation of phosphatidylserine during apoptosis. Thus, cytochrome c-mediated phosphatidylserine oxidation may represent an important component of the apoptotic pathway.
Topics: Animals; Apoptosis; Cell Membrane; Cytochrome c Group; Humans; Hydrogen Peroxide; Oxidants; Oxidative Stress; Phosphatidylserines; Signal Transduction; Substrate Specificity
PubMed: 10899301
DOI: 10.1016/s0014-5793(00)01707-5 -
Biochimica Et Biophysica Acta.... Feb 2018Most biomembranes have an asymmetric structure with regard to phospholipid distribution between the inner and outer leaflets of the lipid bilayers. Control of the...
Most biomembranes have an asymmetric structure with regard to phospholipid distribution between the inner and outer leaflets of the lipid bilayers. Control of the asymmetric distribution plays a pivotal role in several cellular functions such as intracellular membrane fusion and cell division. The mechanism by which membrane asymmetry and its alteration function in these transformation processes is not yet clear. To understand the significance of membrane asymmetry on trafficking and metabolism of intracellular vesicular components, a system that experimentally reproduces the asymmetric nature of biomembranes is essential. Here, we succeeded in obtaining asymmetric vesicles by means of transphosphatidylation reactions with phospholipase D (PLD), which acts exclusively on phosphatidylcholine (PC) present in the outer leaflet of vesicles. By treating PC vesicles with PLD in the presence of 1.7M serine and 0.3M ethanolamine, we obtained asymmetric vesicles that are topologically similar to intracellular vesicles containing phosphatidylserine and phosphatidylethanolamine in the cytosolic leaflet. PLD and other unwanted compounds could be removed by trypsin digestion followed by dialysis. Our established technique has a great advantage over conventional methods in that asymmetric vesicles can be provided at high yield and high efficiency, which is requisite for most physicochemical assays.
Topics: Cell Membrane; Cytoplasmic Vesicles; Lipid Bilayers; Membrane Fusion; Models, Chemical; Molecular Structure; Phosphatidylcholines; Phosphatidylethanolamines; Phosphatidylserines; Phospholipase D; Phospholipids; Spectrometry, Fluorescence
PubMed: 29032301
DOI: 10.1016/j.bbamem.2017.10.011 -
Journal of Cellular Physiology Nov 2016Extracellular vesicles released from cells are under intense investigation for their roles in cell-cell communication and cancer progression. However, individual...
Extracellular vesicles released from cells are under intense investigation for their roles in cell-cell communication and cancer progression. However, individual vesicles have been difficult to probe as their small size renders them invisible by conventional light microscopy. However, as a consequence of their small size these vesicles possess highly curved lipid membranes that offer an unconventional target for curvature-sensing probes. In this article, we present a strategy for using peptide-based biosensors to detect highly curved membranes and the negatively charged membrane lipid phosphatidylserine, we delineate several assays used to validate curvature- and lipid-targeting mechanisms, and we explore potential applications in probing extracellular vesicles released from sources such as apoptotic cells, cancer cells, or activated platelets. J. Cell. Physiol. 231: 2327-2332, 2016. © 2016 Wiley Periodicals, Inc.
Topics: Cell Membrane; Extracellular Vesicles; Lipids; Models, Biological; Molecular Probes; Peptides; Phosphatidylserines
PubMed: 26909741
DOI: 10.1002/jcp.25354 -
The Biochemical Journal Nov 1976The synthesis and turnover of cerebrosides and phospholipids was followed in microsomal and myelin fractions of developing and adult rat brains after an intracerebral... (Comparative Study)
Comparative Study
The synthesis and turnover of cerebrosides and phospholipids was followed in microsomal and myelin fractions of developing and adult rat brains after an intracerebral injection of [U-14C]serine. The kinetics of incorporation of radioactivity into microsomal and myelin cerebrosides indicate the possibility of a precursor-product relationship between cerebrosides of these membranes. The specific radioactivity of myelin cerebrosides was corrected for the deposition of newly formed cerebrosides in myelin. Multiphasic curves were obtained for the decline in specific radioactivity of myelin and microsomal cerebrosides, suggesting different cerebroside pools in these membranes. The half-life of the fast turning-over pool of cerebrosides of myelin was 7 and 22 days for the developing and adult rat brain respectively. The half-life of the slowly turning-over pool of myelin cerebrosides was about 145 days for both groups of animals. The half-life of the rapidly turning-over microsomal cerebrosides was calculated to be 20 and 40 h for the developing and adult animals respectively. The half-life of the intermediate and slowly turning-over microsomal cerebrosides was 11 and 60 days respectively, for both groups of animals. The amount of incorporation of radioactivity into microsomal cerebrosides from L-serine was greatly decreased in the adult animals, and greater amounts of the precursor were directed towards the synthesis of phosphatidylserine. In the developing animals, considerable amounts of cerebrosides were synthesized from L-serine, besides phosphatidylserine. The time-course of incorporation indicated that a precursor-product relationship exists between microsomal and myelin phosphatidylserine. The half-life of microsomal phosphatidylserine was calculated to be about 8 h for the fast turning-over pool in both groups of animals.
Topics: Animals; Brain; Cerebrosides; Female; Half-Life; Male; Microsomes; Myelin Sheath; Phosphatidylserines; Phospholipids; Rats; Serine; Sulfoglycosphingolipids; Time Factors
PubMed: 1008849
DOI: 10.1042/bj1600195 -
Structure (London, England : 1993) Jul 2020In both prokaryotes and eukaryotes, phosphatidylethanolamine (PE), one of the most abundant membrane phospholipids, plays important roles in various membrane functions...
In both prokaryotes and eukaryotes, phosphatidylethanolamine (PE), one of the most abundant membrane phospholipids, plays important roles in various membrane functions and is synthesized through the decarboxylation of phosphatidylserine (PS) by PS decarboxylases (PSDs). However, the catalysis and substrate recognition mechanisms of PSDs remain unclear. In this study, we focused on the PSD from Escherichia coli (EcPsd) and determined the crystal structures of EcPsd in the apo form and PE-bound form at resolutions of 2.6 and 3.6 Å, respectively. EcPsd forms a homodimer, and each protomer has a positively charged substrate binding pocket at the active site. Structure-based mutational analyses revealed that conserved residues in the pocket are involved in PS decarboxylation. EcPsd has an N-terminal hydrophobic helical region that is important for membrane binding, thereby achieving efficient PS recognition. These results provide a structural basis for understanding the mechanism of PE biosynthesis by PSDs.
Topics: Binding Sites; Carboxy-Lyases; Cell Membrane; Conserved Sequence; Escherichia coli; Escherichia coli Proteins; Mutation; Phosphatidylethanolamines; Phosphatidylserines; Protein Binding
PubMed: 32402247
DOI: 10.1016/j.str.2020.04.006 -
The Journal of Clinical Investigation Jul 2013Apoptotic cells are rapidly phagocytosed by macrophages, a process that represents a critical step in tissue remodeling, immune responses, and the resolution of...
Apoptotic cells are rapidly phagocytosed by macrophages, a process that represents a critical step in tissue remodeling, immune responses, and the resolution of inflammation. In 1998, Peter Henson, Donna Bratton, and colleagues at National Jewish Health demonstrated that phagocytosis of apoptotic cells actively suppresses inflammation by inhibiting the production of inflammatory cytokines and inducing production of antiinflammatory factors, including TGF-β and prostaglandin E2. Here they discuss the evolving relationship among apoptosis, phagocytosis, and inflammation.
Topics: Animals; Apoptosis; Cell Membrane; Dinoprostone; Humans; Inflammation Mediators; Macrophages; Phagocytosis; Phosphatidylserines; Receptors, Cell Surface; Transforming Growth Factor beta
PubMed: 23863635
DOI: 10.1172/JCI69344 -
PloS One 2021The phospholipid phosphatidylserine (PS) is a key signaling molecule and binding partner for many intracellular proteins. PS is normally found on the inner surface of...
The phospholipid phosphatidylserine (PS) is a key signaling molecule and binding partner for many intracellular proteins. PS is normally found on the inner surface of the cell membrane, but PS can be flipped to the outer surface in a process called PS exposure. PS exposure is important in many cell functions, yet the mechanisms that control PS exposure have not been extensively studied. Copines (Cpn), found in most eukaryotic organisms, make up a family of calcium-dependent phospholipid binding proteins. In Dictyostelium, which has six copine genes, CpnA strongly binds to PS and translocates from the cytosol to the plasma membrane in response to a rise in calcium. Cells lacking the cpnA gene (cpnA-) have defects in adhesion, chemotaxis, membrane trafficking, and cytokinesis. In this study we used both flow cytometry and fluorescent microscopy to show that cpnA- cells have increased adhesion to beads and bacteria and that the increased adhesion was not due to changes in the actin cytoskeleton or cell surface proteins. We found that cpnA- cells bound higher amounts of Annexin V, a PS binding protein, than parental cells and showed that unlabeled Annexin V reduced the increased cell adhesion property of cpnA- cells. We also found that cpnA- cells were more sensitive to Polybia-MP1, which binds to external PS and induces cell lysis. Overall, this suggests that cpnA- cells have increased PS exposure and this property contributes to the increased cell adhesion of cpnA- cells. We conclude that CpnA has a role in the regulation of plasma membrane lipid composition and may act as a negative regulator of PS exposure.
Topics: Cell Adhesion; Cell Membrane; Dictyostelium; Mutation; Phosphatidylserines; Protozoan Proteins
PubMed: 34043641
DOI: 10.1371/journal.pone.0250710 -
Revista Da Sociedade Brasileira de... Apr 2016Leishmaniasis is a disease caused by the protozoan Leishmania that resides mainly in mononuclear phagocytic system tissues. Pentavalent antimonials are the main...
INTRODUCTION
Leishmaniasis is a disease caused by the protozoan Leishmania that resides mainly in mononuclear phagocytic system tissues. Pentavalent antimonials are the main treatment option, although these drugs have toxic side effects and high resistance rates. A potentially alternative and more effective therapeutic strategy is to use liposomes as carriers of the antileishmanial agents. The aims of this study were to develop antimonial drugs entrapped into phosphatidylserine liposomes and to analyze their biological and physicochemical characteristics.
METHODS
Liposomes containing meglumine antimoniate (MA) or pentavalent antimony salt (Sb) were obtained through filter extrusion (FEL) and characterized by transmission electron microscopy. Promastigotes of Leishmania infantum were incubated with the drugs and the viability was determined with a tetrazolium dye (MTT assay). The effects of these drugs against intracellular amastigotes were also evaluated by optical microscopy, and mammalian cytotoxicity was determined by an MTT assay.
RESULTS
Liposomes had an average diameter of 162nm. MA-FEL showed inhibitory activity against intracellular L. infantum amastigotes, with a 50% inhibitory concentration (IC50) of 0.9μg/mL, whereas that of MA was 60μg/mL. Sb-FEL showed an IC50 value of 0.2μg/mL, whereas that of free Sb was 9μg/mL. MA-FEL and Sb-FEL had strong in vitro activity that was 63-fold and 39-fold more effective than their respective free drugs. MA-FEL tested at a ten-times higher concentration than Sb-FEL did not show cytotoxicity to mammalian cells, resulting in a higher selectivity index.
CONCLUSIONS
Antimonial drug-containing liposomes are more effective against Leishmania-infected macrophages than the non-liposomal drugs.
Topics: Animals; Antimony Sodium Gluconate; Antiprotozoal Agents; Cricetinae; Dose-Response Relationship, Drug; Inhibitory Concentration 50; Leishmania infantum; Liposomes; Macrophages, Peritoneal; Meglumine; Meglumine Antimoniate; Mice; Mice, Inbred BALB C; Organometallic Compounds; Parasitic Sensitivity Tests; Phosphatidylserines
PubMed: 27192589
DOI: 10.1590/0037-8682-0041-2016