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Endothelin stimulates phospholipase D in striatal astrocytes
S Desagher1, J Cordier, J Glowinski
1Chaire de Neuropharmacologie, INSERM U114, Collège de France, Paris, France.
Journal of Neurochemistry
|January 1, 1997
Summary
Endothelin (ET)-1 activates phospholipase D (PLD) in mouse striatal astrocytes via Gi/Go protein and protein kinase C, independent of cyclic AMP but dependent on extracellular calcium. This mechanism also functions in other brain regions.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Astrocytes play crucial roles in brain function.
- Phospholipase D (PLD) is involved in cellular signaling pathways.
- Endothelin (ET) peptides are potent vasoactive substances with diverse physiological effects.
Purpose of the Study:
- To investigate the role of endothelin (ET)-1 in activating phospholipase D (PLD) in primary mouse striatal astrocytes.
- To elucidate the signaling pathways involved in ET-1-induced PLD activation.
Main Methods:
- Primary cultures of mouse striatal astrocytes were used.
- Cells were prelabeled with [3H]myristic acid.
- PLD activity was assessed by measuring the formation of [3H]phosphatidylethanol in the presence of ethanol.
- The effects of pertussis toxin, protein kinase C inhibitors (Ro 31-8220), phorbol 12-myristate 13-acetate (PMA), and various signaling modulators were examined.
- Extracellular calcium dependence was assessed.
Main Results:
- ET-1 induced a time-dependent formation of [3H]phosphatidic acid and [3H]diacylglycerol, indicating PLD activation.
- ET-1 and ET-3 were equipotent in stimulating PLD activity.
- Pertussis toxin partially inhibited ET-1's effect, suggesting Gi/Go protein involvement.
- Inhibition or down-regulation of protein kinase C abolished ET-1-induced PLD stimulation.
- ET-1-induced PLD activation was independent of cyclic AMP.
- ET-1 and PMA stimulated PLD via distinct, additive pathways.
- ET-1-induced PLD activation, unlike PMA's, was dependent on extracellular calcium.
- ET-1, ET-3, and PMA stimulated PLD in astrocytes from various brain regions.
Conclusions:
- ET-1 activates PLD in striatal astrocytes through at least two distinct mechanisms.
- One pathway involves Gi/Go proteins and protein kinase C and is calcium-independent.
- Another pathway, possibly involving calcium, is also activated by ET-1.
- These findings highlight the complex regulation of PLD by ET-1 in astrocytes and suggest broader implications across different brain regions.