Related Experiment Videos
Activations of mitogen-activated protein kinases and phospholipase D in A7r5 vascular smooth muscle cells
L G Jones1, K M Ella, C D Bradshaw
1Department of Cell and Molecular Pharmacology, Medical University of South Carolina, Charleston 29425.
Abstract:
Activation of mitogen-activated protein kinases (MAPKs) was examined in the A7r5 rat vascular smooth muscle cell line. Treatment of A7r5 cells with vasopressin, phorbol ester (PMA), or serum resulted in activation of two MAPKs, Erk-1 and Erk-2. Phosphatidylinositol-specific phospholipase C was activated in response to vasopressin but not to PMA. Vasopressin and PMA both caused maximal activation of PLD within 5 minutes. Application of bacterial phospholipase D (PLD) to A7r5 cells increased phosphatidic acid to levels similar to those seen with vasopressin or PMA. Acute exposure of the cells to vasopressin, PMA, or PLD increased phosphorylation of many of the same cytosolic and membrane proteins. However, bacterial PLD did not promote significant activation of Erk-1 and Erk-2. Phosphatidic acid and lysophosphatidic acid (LPA) likewise did not stimulate MAPK activity in A7r5 cells. Serum and vasopressin stimulated DNA synthesis when present for more than 30 min, while PLD, PMA, phosphatidic acid, and LPA were not mitogenic. These data suggest that activations of MAPKs and PLD are concurrent but independent responses to vasopressin in A7r5 cells. Acute activation of these enzymes is not sufficient to simulate DNA synthesis.
Insights
Vasopressin activates mitogen-activated protein kinases (MAPKs) and phospholipase D (PLD) concurrently but independently in A7r5 cells. However, acute activation of these pathways does not stimulate DNA synthesis.
Area of Science:
- Cellular Biology
- Biochemistry
- Molecular Biology
Background:
- Mitogen-activated protein kinases (MAPKs) are crucial signaling molecules involved in cellular processes.
- Phospholipase D (PLD) plays a role in various cellular functions, including signal transduction.
- Understanding the interplay between MAPKs and PLD in vascular smooth muscle cells is important for cellular signaling research.
Purpose of the Study:
- To investigate the activation of MAPKs and PLD in response to vasopressin in A7r5 cells.
- To determine the relationship between MAPK and PLD activation.
- To assess the role of these pathways in cellular proliferation.
Main Methods:
- A7r5 rat vascular smooth muscle cells were treated with vasopressin, phorbol ester (PMA), or serum.
- Activation of MAPKs (Erk-1 and Erk-2) and PLD was measured.
- Phosphorylation of cytosolic and membrane proteins was analyzed.
- DNA synthesis was assessed following various treatments.
Main Results:
- Vasopressin, PMA, and serum activated Erk-1 and Erk-2 MAPKs.
- Vasopressin and PMA induced rapid PLD activation.
- Bacterial PLD, phosphatidic acid, and lysophosphatidic acid did not activate MAPKs.
- Only vasopressin and serum stimulated DNA synthesis after prolonged exposure.
Conclusions:
- MAPK and PLD activations are concurrent but independent responses to vasopressin in A7r5 cells.
- Acute activation of MAPKs and PLD is insufficient to induce DNA synthesis.
- These findings clarify the signaling pathways involved in vascular smooth muscle cell responses.