1. Hematopoietic cells expressing the peripheral cannabinoid receptor migrate in response to the endocannabinoid 2-arachidonoyglycerol
- Author
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Ruud Delwel, Sandra E. Verbakel, M. Maccarrone, Meritxell Alberich Jordà, Peter J. M. Valk, Allessandro Finazzi-Agrò, Yolanda Vankan-Berkhoudt, Bob Löwenberg, and Hematology
- Subjects
medicine.medical_specialty ,Cannabinoid receptor ,Myeloid ,Receptors, Drug ,Immunology ,Arachidonic Acids ,Thymus Gland ,Biology ,Ligands ,Transfection ,Biochemistry ,Glycerides ,Mice ,Internal medicine ,Cannabinoid Receptor Modulators ,medicine ,Cannabinoid receptor type 2 ,Tumor Cells, Cultured ,Animals ,Drug Interactions ,Myeloid Cells ,Receptor ,Receptors, Cannabinoid ,B-Lymphocytes ,Cannabinoids ,Chemotaxis ,Myeloid leukemia ,Cell Biology ,Hematology ,medicine.disease ,Molecular biology ,Leukemia ,Haematopoiesis ,medicine.anatomical_structure ,Endocrinology ,Leukemia, Myeloid ,Cytokines ,lipids (amino acids, peptides, and proteins) ,Spleen ,Endocannabinoids - Abstract
Cb2 is a novel protooncogene encoding the peripheral cannabinoid receptor. Previous studies demonstrated that 2 distinct noncoding first exons exist: exon-1A and exon-1B, which both splice to protein-coding exon-2. We demonstrate that in retrovirally induced murine myeloid leukemia cells with proviral insertion in Cb2, exon-1B/exon-2 Cb2 messenger RNA levels have been increased, resulting in high receptor numbers. In myeloid leukemia cells without virus insertion in this locus, low levels of only exon-1A/exon-2 Cb2 transcripts were present and receptors could not be detected. To elucidate the function of Cb2 in myeloid leukemia cells, a set of in vitro experiments was carried out using 32D/G-CSF-R (granulocyte colony-stimulating factor receptor) cells transfected with exon-1B/exon-2 Cb2 complementary DNA and a myeloid cell line carrying a virus insertion in Cb2 (ie, NFS 78). We demonstrate that a major function of the Cb2 receptor is stimulation of migration as determined in a transwell assay. Exposure of Cb2-expressing cells to different cannabinoids showed that the true ligand for Cb2 is 2-arachidonoylglycerol (2-AG), which may act as chemoattractant and as a chemokinetic agent. Furthermore, we observed a significant synergistic activity between 2-AG and interleukin-3 or G-CSF, suggesting cross-talk between the different receptor systems. Radioactive-ligand binding studies revealed significant numbers of Cb2 receptors in normal spleen. Transwell experiments carried out with normal mouse spleen cells showed 2-AG-induced migration of B220-, CD19-, immunoglobulin M-, and immunoglobulin D-expressing B lymphocytes. Our study demonstrates that a major function of Cb2 receptor expressed on myeloid leukemia cells or normal splenocytes is stimulation of migration.
- Published
- 2002