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Functional CB1 cannabinoid receptors in human vascular endothelial cells
J Liu1, B Gao, F Mirshahi
1Department of Pharmacology & Toxicology, Medical College of Virginia of Virginia Commonwealth University, Richmond, VA 23298, USA.
The Biochemical Journal
|March 4, 2000
Summary
Cannabinoid CB1 receptors are present in human vascular endothelial cells and activate mitogen-activated protein (MAP) kinase signaling. Anandamide activates MAP kinase via both CB1-dependent and independent pathways, influencing endothelial cell growth.
Area of Science:
- Endocrinology and Metabolism
- Cell Biology
- Molecular Biology
Background:
- Cannabinoid CB1 receptors are expressed in various tissues, including vascular endothelium.
- Endothelial cells play crucial roles in vascular function and homeostasis.
- Mitogen-activated protein (MAP) kinase pathways are critical for cellular signaling and responses.
Purpose of the Study:
- To investigate the presence and function of cannabinoid CB1 receptors in human vascular endothelial cells.
- To determine the role of CB1 receptors in mediating cellular responses, specifically MAP kinase activation.
- To elucidate the signaling pathways involved in anandamide-induced MAP kinase activation in endothelial cells.
Main Methods:
- Reverse transcription-polymerase chain reaction (RT-PCR) to detect CB1 receptor mRNA.
- Radioligand binding assays using [(125)I]AM-251 to identify CB1 receptor-binding sites.
- Stimulation with cannabinoid agonists (HU-210, anandamide) and antagonists (SR141716A) to assess receptor activity.
- CB1 receptor antisense oligonucleotides to confirm receptor involvement.
- Western blotting or kinase assays to measure MAP kinase activation (ERK, p38, JNK).
Main Results:
- CB1 receptor mRNA and binding sites were detected in human aortic and hepatic artery endothelial cells, and ECV304 cells.
- Synthetic cannabinoid HU-210 and endogenous anandamide activated MAP kinase in ECV304 cells.
- SR141716A (CB1 antagonist) blocked HU-210-induced activation and partially inhibited anandamide-induced activation.
- CB1 receptor antisense oligonucleotides mimicked the inhibitory effect of SR141716A.
- Anandamide-induced MAP kinase activation involved genistein-sensitive tyrosine kinases, protein kinase C (PKC), p38 kinase, and c-Jun kinase.
- Evidence suggests both CB1-dependent and CB1-independent pathways for anandamide-induced MAP kinase activation.
Conclusions:
- Human vascular endothelial cells express functional CB1 receptors coupled to the MAP kinase cascade.
- Anandamide activates MAP kinase in endothelial cells through both CB1 receptor-dependent and independent mechanisms.
- These signaling pathways may play a role in regulating endothelial cell growth and proliferation.