scholarly journals Glycine Induces Migration of Microglial BV-2 Cells via SNAT-Mediated Cell Swelling

2018 ◽  
Vol 50 (4) ◽  
pp. 1460-1473 ◽  
Author(s):  
Michael Kittl ◽  
Heidemarie Dobias ◽  
Marlena Beyreis ◽  
Tobias Kiesslich ◽  
Christian Mayr ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Membrane Potential ◽  
Amino Acid ◽  
Cell Membrane ◽  
Cell Volume ◽  
Cell Membrane Potential ◽  
Microglial Cells ◽  
Cell Swelling ◽  
Electrophysiological Recordings ◽  
A Cell

Background/Aims: The neutral, non-essential amino acid glycine has manifold functions and effects under physiological and pathophysiological conditions. Besides its function as a neurotransmitter in the central nervous system, glycine also exerts immunomodulatory effects and as an osmolyte it participates in cell volume regulation. During phagocytosis, glycine contributes to (local) cell volume-dependent processes like lamellipodium formation. Similar to the expansion of the lamellipodium we assume that glycine also affects the migration of microglial cells in a cell volume-dependent manner. Methods: Mean cell volume (MCV) and cell migration were determined using flow cytometry and trans-well migration assays, respectively. Electrophysiological recordings of the cell membrane potential (Vmem) and swelling-dependent chloride (Cl-) currents (IClswell, VSOR, VRAC) were performed using the whole-cell patch clamp technique. Results: In the murine microglial cell line BV-2, flow cytometry analysis revealed that glycine (5 mM) increases the MCV by ∼9%. The glycine-dependent increase in MCV was suppressed by the partial sodium-dependent neutral amino acid transporter (SNAT) antagonist MeAIB and augmented by the Cl- current blocker DCPIB. Electrophysiological recordings showed that addition of glycine activates a Cl- current under isotonic conditions resembling features of the swelling-activated Cl- current (IClswell). The cell membrane potential (Vmem) displayed a distinctive time course after glycine application; initially, glycine evoked a rapid depolarization mediated by Na+-coupled glycine uptake via SNAT, followed by a further gradual depolarization, which was fully suppressed by DCPIB. Interestingly, glycine significantly increased migration of BV-2 cells, which was suppressed by MeAIB, suggesting that SNAT is involved in the migration process of microglial cells. Conclusion: We conclude that glycine acts as a chemoattractant for microglial cells presumably by a cell volume-dependent mechanism involving SNAT-mediated cell swelling.

Associations between transports of alanine and cations across cell membrane in rat hepatocytes

1986 ◽  
Vol 251 (5) ◽  
pp. G575-G584 ◽  
Author(s):  
L. O. Kristensen
Keyword(s):  
Amino Acid ◽  
Cell Membrane ◽  
Cell Volume ◽  
Driving Force ◽  
Rat Hepatocytes ◽  
The Body ◽  
Cell Swelling ◽  
Molar Ratio ◽  
Regulatory Processes ◽  
Intracellular Content

Alanine transport across the liver cell membrane is a regulated key process in the amino acid metabolism of the body. The majority of alanine influx in hepatocytes is Na+ dependent and is stimulated by intracellular negativity. The molar ratio between cotransported Na+ and alanine is 1:1. Alanine efflux is stimulated by intracellular Na+, whereas the role of the membrane potential is unclear. The transmembrane Na+ electrochemical gradient seems to be the exclusive driving force for cellular alanine accumulation. At a physiological Na+ gradient, intracellular alanine can exceed the extracellular concentration about 20-fold, but metabolism will exert a conspicuous sink effect. Na+-coupled uptake of alanine appears to be a challenge that triggers a sequence of regulatory events: increased cellular Na+ leads to an increase in active Na+-K+-pumping and thus in K+ influx; influx of alanine and cations tends to increase the cellular content of osmotically active substances implying a tendency to water uptake; cell swelling, even when modest, induces an increase in the permeability of a conductive pathway for K+ leading to net efflux of K+ (with accompanying anions) and cellular hyperpolarization. Net efflux of K+ prevents excessive cell volume increase during amino acid accumulation, whereas hyperpolarization tends to support the driving force for alanine influx (and anion efflux). The pathway for K+ efflux needs further characterization, but it may involve single-file diffusion with Ca2+ as an activator. This model suggests that cell volume regulatory processes mainly serve to compensate for changes in intracellular content of ions and metabolites during activation of specialized cellular processes.

Pressure-induced smooth muscle cell depolarization in pulmonary arteries from control and chronically hypoxic rats does not cause myogenic vasoconstriction

2005 ◽  
Vol 98 (3) ◽  
pp. 1119-1124 ◽  
Author(s):  
Jay S. Naik ◽  
Scott Earley ◽  
Thomas C. Resta ◽  
Benjimen R. Walker
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Cell Membrane ◽  
Pulmonary Vascular Resistance ◽  
Vascular Resistance ◽  
Pulmonary Arteries ◽  
Barometric Pressure ◽  
Cell Membrane Potential ◽  
Intraluminal Pressure ◽  
Dose Dependent

Chronic obstructive pulmonary diseases, as well as prolonged residence at high altitude, can result in generalized airway hypoxia, eliciting an increase in pulmonary vascular resistance. We hypothesized that a portion of the elevated pulmonary vascular resistance following chronic hypoxia (CH) is due to the development of myogenic tone. Isolated, pressurized small pulmonary arteries from control (barometric pressure ≅ 630 Torr) and CH (4 wk, barometric pressure = 380 Torr) rats were loaded with fura 2-AM and perfused with warm (37°C), aerated (21% O2-6% CO2-balance N2) physiological saline solution. Vascular smooth muscle (VSM) intracellular Ca2+ concentration ([Ca2+]i) and diameter responses to increasing intraluminal pressure were determined. Diameter and VSM cell [Ca2+]i responses to KCl were also determined. In a separate set of experiments, VSM cell membrane potential responses to increasing luminal pressure were determined in arteries from control and CH rats. VSM cell membrane potential in arteries from CH animals was depolarized relative to control at each pressure step. VSM cells from both groups exhibited a further depolarization in response to step increases in intraluminal pressure. However, arteries from both control and CH rats distended passively to increasing intraluminal pressure, and VSM cell [Ca2+]i was not affected. KCl elicited a dose-dependent vasoconstriction that was nearly identical between control and CH groups. Whereas KCl administration resulted in a dose-dependent increase in VSM cell [Ca2+]i in arteries taken from control animals, this stimulus elicited only a slight increase in VSM cell [Ca2+]i in arteries from CH animals. We conclude that the pulmonary circulation of the rat does not demonstrate pressure-induced vasoconstriction.

Cell Membrane Potential Model Circuit Lab

2018 ◽  
Vol 56 (8) ◽  
pp. 540-543
Author(s):  
Mickey D. Kutzner ◽  
J. Michael Bryson
Keyword(s):  
Membrane Potential ◽  
Cell Membrane ◽  
Potential Model ◽  
Cell Membrane Potential ◽  
Model Circuit

scholarly journals Signaling mechanism by the Staphylococcus aureus two-component system LytSR: role of acetyl phosphate in bypassing the cell membrane electrical potential sensor LytS

F1000Research ◽  
2016 ◽  
Vol 4 ◽  
pp. 79 ◽  
Author(s):  
Kevin Patel ◽  
Dasantila Golemi-Kotra
Keyword(s):  
Staphylococcus Aureus ◽  
Membrane Potential ◽  
Cell Membrane ◽  
Electrical Potential ◽  
Cell Membrane Potential ◽  
Acetyl Phosphate ◽  
Two Component System ◽  
Component System ◽  
Two Component ◽  
Membrane Electrical Potential

The two-component system LytSR has been linked to the signal transduction of cell membrane electrical potential perturbation and is involved in the adaptation of Staphylococcus aureus to cationic antimicrobial peptides. It consists of a membrane-bound histidine kinase, LytS, which belongs to the family of multiple transmembrane-spanning domains receptors, and a response regulator, LytR, which belongs to the novel family of non-helix-turn-helix DNA-binding domain proteins. LytR regulates the expression of cidABC and lrgAB operons, the gene products of which are involved in programmed cell death and lysis. In vivo studies have demonstrated involvement of two overlapping regulatory networks in regulating the lrgAB operon, both depending on LytR. One regulatory network responds to glucose metabolism and the other responds to changes in the cell membrane potential. Herein, we show that LytS has autokinase activity and can catalyze a fast phosphotransfer reaction, with 50% of its phosphoryl group lost within 1 minute of incubation with LytR. LytS has also phosphatase activity. Notably, LytR undergoes phosphorylation by acetyl phosphate at a rate that is 2-fold faster than the phosphorylation by LytS. This observation is significant in lieu of the in vivo observations that regulation of the lrgAB operon is LytR-dependent in the presence of excess glucose in the medium. The latter condition does not lead to perturbation of the cell membrane potential but rather to the accumulation of acetate in the cell. Our study provides insights into the molecular basis for regulation of lrgAB in a LytR-dependent manner under conditions that do not involve sensing by LytS.

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