scholarly journals Unprocessed serum glycosylphosphatidylinositol-anchored proteins are correlated to metabolic states

2018 ◽  
Author(s):  
Günter A. Müller ◽  
Andreas W. Herling ◽  
Kerstin Stemmer ◽  
Andreas Lechner ◽  
Matthias H. Tschöp
Keyword(s):  
Body Weight ◽  
Phase Shift ◽  
Acoustic Waves ◽  
Plasma Membranes ◽  
Surface Acoustic Waves ◽  
Chip Surface ◽  
Metabolic States ◽  
Isolated Adipocytes ◽  
Adipocyte Plasma Membranes ◽  
Isolated Rat

To study the possibility that components of eukaryotic plasma membranes are released in spontaneous or controlled fashion, a chip-based sensor was developed for complete glycosylphosphatidylinositol-anchored proteins (GPI-AP), which may form together with (phospho)lipids so far unknown (non-vesicular) extracellular complexes (GLEC). The sensor relies on changes in phase shift and amplitude of surface acoustic waves propagating over the chip surface upon specific capturing of the GPI-AP and detection of associated phospholipids and renders isolation of the labile GLEC unnecessary. GLEC were found to be released from isolated rat adipocyte plasma membranes immobilized on the chip, dependent on the flow rate and composition of the buffer stream. Moreover, incubation medium of isolated adipocytes and serum of rats are sources for GLEC which enables their differentiation according to cell size and genotype or body weight, respectively, as well as human serum.

scholarly journals Chip-based sensing for release of unprocessed cell surface proteins in vitro and in serum and its (patho)physiological relevance

2019 ◽  
Vol 317 (2) ◽  
pp. E212-E233 ◽  
Author(s):  
Günter A. Müller ◽  
Andreas W. Herling ◽  
Kerstin Stemmer ◽  
Andreas Lechner ◽  
Matthias H. Tschöp
Keyword(s):  
Cell Surface ◽  
Acoustic Waves ◽  
Plasma Membranes ◽  
Surface Acoustic Waves ◽  
Microfluidic Channel ◽  
Surface Proteins ◽  
Chip Surface ◽  
Cell Surface Proteins ◽  
Adipocyte Plasma Membranes

To study the possibility that certain components of eukaryotic plasma membranes are released under certain (patho)physiological conditions, a chip-based sensor was developed for the detection of cell surface proteins, which are anchored at the outer leaflet of eukaryotic plasma membranes by a covalently attached glycolipid, exclusively, and might be prone to spontaneous or regulated release on the basis of their amphiphilic character. For this, unprocessed, full-length glycosylphosphatidylinositol-anchored proteins (GPI-AP), together with associated phospholipids, were specifically captured and detected by a chip- and microfluidic channel-based sensor, leading to changes in phase and amplitude of surface acoustic waves (SAW) propagating over the chip surface. Unprocessed GPI-AP in complex with lipids were found to be released from rat adipocyte plasma membranes immobilized on the chip, which was dependent on the flow rate and composition of the buffer stream. The complexes were identified in the incubation medium of primary rat adipocytes, in correlation to the cell size, and in rat as well as human serum. With rats, the measured changes in SAW phase shift, reflecting specific mass/size or amount of the unprocessed GPI-AP in complex with lipids, and SAW amplitude, reflecting their viscoelasticity, enabled the differentiation between the lean and obese (high-fat diet) state, and the normal (Wistar) and hyperinsulinemic (Zucker fatty) as well as hyperinsulinemic hyperglycemic (Zucker diabetic fatty) state. Thus chip-based sensing for complexes of unprocessed GPI-AP and lipids reveals the inherently labile anchorage of GPI-AP at plasma membranes and their susceptibility for release in response to (intrinsic/extrinsic) cues of metabolic relevance and may, therefore, be useful for monitoring of (pre-)diabetic disease states.

Stimulation of phosphatidylcholine synthesis by insulin and ATP in isolated rat adipocyte plasma membranes

1986 ◽  
Vol 137 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Frederick L. Kiechle ◽  
Halina Malinski ◽  
Donald R. Strandbergh ◽  
Joseph D. Artiss
Keyword(s):  
Plasma Membranes ◽  
Adipocyte Plasma Membranes ◽  
Phosphatidylcholine Synthesis ◽  
Isolated Rat ◽  
Stimulation Of

Characterization of high-density lipoprotein binding to rat adipocytes and adipocyte plasma membranes

1988 ◽  
Vol 66 (9) ◽  
pp. 986-997 ◽  
Author(s):  
Eva Zsigmond ◽  
Bessie Fong ◽  
Aubie Angel
Keyword(s):  
Adipose Tissue ◽  
Plasma Membranes ◽  
Density Lipoprotein ◽  
Membrane System ◽  
Rat Plasma ◽  
High Density ◽  
High Density Lipoproteins ◽  
Binding Characteristics ◽  
Isolated Adipocytes ◽  
Adipocyte Plasma Membranes

The interaction of high-density lipoproteins (HDL) with adipocytes is important in the regulation of cellular cholesterol flux. To study the mechanisms of HDL binding and cellular processing, we incubated adipocytes isolated from epididymal and perirenal adipose tissue of male Wistar rats (300 g) with HDL1 (1.07–1.10 g/mL) and HDL2 (1.10–1.14 g/mL) fractions separated from rat plasma by gradient ultracentrifugation. Freshly isolated adipocytes were incubated with 125I-labeled HDL for 2 h at 37 °C to determine cell-associated uptake and degradation. Adipocytes from both fat regions showed significant cell-associated HDL1 and HDL2 uptake and very high medium degradation (2- to 6-fold higher than uptake). To assess 125I-labeled HDL binding independent of cellular metabolism, we purified adipocyte plasma membranes from isolated adipocytes and used them in binding assays. Binding of HDL1 and HDL2 in the membrane system was 85–95% specific, sensitive to high NaCl concentrations, and abolished by pronase treatment. In contrast to HDL2 binding, the maximum HDL1 binding to perirenal plasma membranes was significantly higher than its binding to epididymal membranes (7.2 ± 1.3 vs. 4.4 ± 0.2 μg/mg, n = 6, p < 0.05). This increment in HDL1 binding to perirenal membranes represented an EDTA- sensitive, calcium-dependent component. These results indicate that HDL binding to adipocyte plasma membranes depends on both adipose tissue region and HDL subtype. The membrane binding characteristics, taken together with the cellular uptake results, suggest that adipocytes bind and metabolize HDL and that this interaction may involve a protein receptor.

Effect of insulin, S-adenosylhomocysteine, phospholipase C, n-butanol and Triton X-114 on alkaline phosphatase from isolated rat adipocyte plasma membranes

1987 ◽  
Vol 169 (1) ◽  
pp. 133-139 ◽  
Author(s):  
Elizabeth Sykes ◽  
Sandhya Ghag ◽  
Emanuel Epstein ◽  
Frederick L. Kiechle
Keyword(s):  
Alkaline Phosphatase ◽  
Phospholipase C ◽  
Plasma Membranes ◽  
Adipocyte Plasma Membranes ◽  
Triton X ◽  
Isolated Rat

Generation and detection of gigahertz surface acoustic waves using an elastomeric phase-shift mask

2013 ◽  
Vol 114 (14) ◽  
pp. 143102 ◽  
Author(s):  
Dongyao Li ◽  
Peng Zhao ◽  
Ji-Cheng Zhao ◽  
David G. Cahill
Keyword(s):  
Phase Shift ◽  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Phase Shift Mask

Deflecting Rayleigh surface acoustic waves by a meta-ridge with a gradient phase shift

2018 ◽  
Vol 51 (17) ◽  
pp. 175106 ◽  
Author(s):  
Yanlong Xu ◽  
Zhichun Yang ◽  
Liyun Cao
Keyword(s):  
Phase Shift ◽  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Gradient Phase

scholarly journals Insulin stimulation of phospholipid methylation in isolated rat adipocyte plasma membranes.

1984 ◽  
Vol 81 (4) ◽  
pp. 1089-1092 ◽  
Author(s):  
K. L. Kelly ◽  
F. L. Kiechle ◽  
L. Jarett
Keyword(s):  
Plasma Membranes ◽  
Insulin Stimulation ◽  
Adipocyte Plasma Membranes ◽  
Isolated Rat ◽  
Stimulation Of

Focal transformation and the Gouy phase shift of converging one-cycle surface acoustic waves excited by femtosecond laser pulses

2005 ◽  
Vol 30 (15) ◽  
pp. 2019 ◽  
Author(s):  
Al. A. Kolomenskii ◽  
S. N. Jerebtsov ◽  
H. A. Schuessler
Keyword(s):  
Phase Shift ◽  
Femtosecond Laser ◽  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Gouy Phase

scholarly journals Transportation of single cell and microbubbles by phase-shift introduced to standing leaky surface acoustic waves

2011 ◽  
Vol 5 (4) ◽  
pp. 044104 ◽  
Author(s):  
Long Meng ◽  
Feiyan Cai ◽  
Zidong Zhang ◽  
Lili Niu ◽  
Qiaofeng Jin ◽  
...  
Keyword(s):  
Phase Shift ◽  
Single Cell ◽  
Acoustic Waves ◽  
Surface Acoustic Waves

Enhanced binding of phospholipase-A2-modified low density lipoprotein by human adipocytes

1990 ◽  
Vol 68 (11) ◽  
pp. 1243-1249 ◽  
Author(s):  
Madhu K. Natarajan ◽  
Bessie S. Fong ◽  
Aubie Angel
Keyword(s):  
Membrane Protein ◽  
Plasma Membranes ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Low Density ◽  
Human Adipocytes ◽  
Binding Studies ◽  
Modified Ldl ◽  
Isolated Adipocytes ◽  
Adipocyte Plasma Membranes

Recognition of low density lipoprotein (LDL) by human adipocytes is not dependent on the classical LDL (apoprotein B–E) receptor. To assess whether LDL phospholipids have a role in adipocyte-LDL interactions, binding studies were carried out with human LDL modified with cobra venom phospholipase A2 (PLA2) and freshly isolated adipocytes and purified adipocyte plasma membranes prepared from surgical biopsies. LDL incubated with PLA2 showed increased monoacylphospholipid content, decreased diacylphospholipid content, and increased anodic migration on agarose gel electrophoresis. LDL cholesterol, triglyceride, and protein content remained unchanged. Typically, modification of 16 and 47% of LDL phospholipids enhanced specific binding of 125I-labelled LDL to plasma membranes progressively from 3.1 μg LDL bound/mg membrane protein (control) to 5.8 and 28.2 μg LDL bound/mg membrane protein, respectively. Nonspecific binding was not altered significantly. Excess unlabelled native LDL and high density lipoprotein (HDL3) effectively inhibited binding of PLA2-modified LDL. Freshly isolated adipocytes also showed enhanced binding and uptake of PLA2-modified LDL (0.1 vs. 0.9 μg LDL/(106 cells∙2 h), control vs. modified). The results demonstrate that alterations of LDL phospholipids significantly enhance LDL binding and suggest a regulatory role for phospholipids in lipoprotein–cell interaction. Furthermore, the results support the view that human adipose tissue may be involved in the metabolism of modified lipoproteins, in vivo.Key words: low density lipoprotein, adipocyte, phospholipase, lipoprotein receptors.

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