| 1. |
|
|
| 2. |
|
|
| 3. |
- Gizurarson, Sigfus, et al.
(författare)
-
Electrophysiological Effects of Lysophosphatidylcholine on HL-1 Cardiomyocytes Assessed with a Microelectrode Array System
- 2012
-
Ingår i: Cellular Physiology and Biochemistry. - : S. Karger AG. - 1015-8987 .- 1421-9778. ; 30:2, s. 477-488
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Sudden death due to malignant ventricular arrhythmias is the most important cause of death in acute myocardial infarction. Improved knowledge about the pathophysiology underlying these arrhythmias is essential in the search for new anti-arrhythmic strategies. Lysophosphatidylcholine (LPC), a hydrolysis product of (membrane) phospholipid degradation, is one of the most potent pro-arrhythmic substances that accumulate in the human heart during myocardial ischemia. The aim of this study was to set up and validate an in vitro experimental system for studies on the effects of LPC on electrophysiological parameters in beating cardiomyocytes. Methods and Results: Spontaneously beating HL-1 cardiomyocytes were cultured on multielectrode array microchips for three days for the recording of electrical activities in the form of field potentials (FP). FPs were recorded at baseline and after addition of 2, 4, 8, 12, 16, 20, and 24 mu M of LPC to the cell medium (n=9). We found that LPC could induce rapid effects on electrical parameters in the HL-1 cells. The overall half-maximal effective concentration (EC50) of LPC was around 12 mu M. The beating rate and peak-peak amplitude of FP thus decreased at concentrations >= 12 mu M and were inversely proportional to increased LPC concentration. The duration of FP was significantly prolonged with LPC above 12 mu M and was concentration-dependent. LPC delayed signal propagation, an effect which was mimicked by blocking gap junctions with heptanol and attenuated by pre-treatment with isoprenaline and atropine. Finally, asynchronous activity was induced by LPC at >12 mu M. Conclusions: LPC induced prompt and pronounced electrophysiological alterations that may underlie its observed pro-arrhythmic properties. Our in vitro model with HL-1 cells and microelectrode array system may be a useful tool for preclinical studies of electrophysiological effects of various pathophysiological concepts. Copyright (C) 2012 S Karger AG, Basel
|
|
| 4. |
- Konstantinidis, Georgios, et al.
(författare)
-
Regulation of Myosin Light Chain Function by BMP Signaling Controls Actin Cytoskeleton Remodeling
- 2011
-
Ingår i: Cellular Physiology and Biochemistry. - : S. Karger AG. - 1015-8987 .- 1421-9778. ; 28:5, s. 1031-1044
-
Tidskriftsartikel (refereegranskat)abstract
- Background/Aims: Actin cytoskeleton dynamics support and coordinate signaling events that control cell proliferation, differentiation and migration. Growth factors provide essential signals that act on multi-protein complexes that regulate actin assembly with myosin. We previously analyzed the action of the transforming growth factor β (TGF-β) and now extend our studies to the bone morphogenetic protein (BMP) 7, an important regulator of stem cell function and bone differentiation. Methods: Using a well-established cell model of actin dynamics, Swiss3T3 fibroblasts, we applied cell biological and biochemical approaches to monitor the pathway that links the BMP-7 receptors to the acto-myosin complex. Results: We demonstrate that BMP-7 induces actin and focal adhesion remodeling in starved fibroblasts as potently as TGF-β. BMP-7 mediates changes of actin dynamics via the kinase ROCK1 and induces rapid activation of RhoA and RhoB with concomitant inactivation of Cdc42. These molecular events correlate well with induction of phosphorylation on Ser19 of the myosin light chain, but not with LIMK1 kinase activation. Depletion of endogenous myosin light chain inhibits actin remodeling induced by BMP-7. This novel pathway regulates fibroblast migration without affecting cell proliferation. Conclusion: We establish a BMP-Rho-ROCK1 pathway, which targets myosin light chain to control actin remodeling in fibroblasts.
|
|
| 5. |
- Papadimitriou, Elsa, et al.
(författare)
-
TGFβ-induced early activation of the small GTPase RhoA is Smad2/3-independent and involves Src and the guanine nucleotide exchange factor Vav2
- 2011
-
Ingår i: Cellular Physiology and Biochemistry. - Basel : Karger. - 1015-8987 .- 1421-9778. ; 28:2, s. 229-238
-
Tidskriftsartikel (refereegranskat)abstract
- TGFβ has been shown to induce short- and long-term actin reorganization controlled by Rho-GTPase signaling. A number of direct Smad target genes, rapidly activated by TGFβ, have been previously reported to control the long-term Rho activation and actin reorganization. However, the molecular mechanisms that regulate the prompt stimulation of Rho GTPases by TGFβ remain unknown. In the present study we report that TGFβ rapidly stimulated RhoA and RhoB activation in JEG3 choriocarcinoma cells that lack endogenous Smad3. Inhibition of Smad2 expression via siRNA-mediated silencing or by blocking its phosphorylation using the TβRI inhibitor SB431542 did not prevent the early RhoA/B activation by TGFβ indicating that this effect is Smad2/3-independent. Pre-treatment of the cells with the general tyrosine kinase inhibitor Genistein blocked the TGFβ-induced early RhoA activation. In line with this finding, TGFβ-stimulation resulted in a quick activation of the non-receptor tyrosine kinase Src, followed by activation of the guanine nucleotide exchange factor (GEF) Vav2. Inhibition of Src kinase by the selective inhibitor of the Src family tyrosine kinases PP2 totally blocked the early TGFβ-induced RhoA activation. Similarly, Vav2 silencing via siRNA reduced the TGFβ-induced RhoA activation implying that the rapid Src/Vav2 stimulation was effective in regulating RhoA activation. Our present findings provide for the first time a clear evidence for the role of Src and Vav2-GEF in the early Smad2/3-independent Rho activation by TGFβ.
|
|
| 6. |
|
|
| 7. |
|
|
