Alkylindole-sensitive receptors modulate microglial cell migration and proliferation.
Ligands targeting G protein-coupled receptors (GPCR) expressed by microglia have been shown to regulate distinct components of their activation process, including cell proliferation, migration and differentiation into M1 or M2 phenotypes. Cannabinoids, including the active component of the Cannabis plant, tetrahydrocannabinol (THC), and the synthetic alkylindole (AI) compound, WIN55212-2 (WIN-2), activate two molecularly identified GPCRs: CB1 and CB2 . Previous studies reported that WIN-2 activates an additional unknown GPCR that is not activated by plant-derived cannabinoids, and evidence indicates that microglia express these receptors. Detailed studies on the role of AI-sensitive receptors in microglial cell activation were difficult as no selective pharmacological tools were available. Here, three newly-developed AI analogues allowed us to determine if microglia express AI-sensitive receptors and if so, study how they regulate the microglial cell activation process. We found that mouse microglia in primary culture express functional AI-sensitive receptors as measured by radioligand binding and changes in intracellular cAMP levels, and that these receptors control both basal and ATP-stimulated migration. AI analogues inhibit cell proliferation stimulated by macrophage-colony stimulating factor (M-CSF) without affecting basal cell proliferation. Remarkably, AI analogues do not control the expression of effector proteins characteristic of M1 or M2 phenotypes; yet activating microglia with M1 and M2 cytokines reduces the microglial response to AI analogues. Our results suggest that microglia express functional AI-sensitive receptors that control select components of their activation process. Agonists of these novel targets might represent a novel class of therapeutics to influence the microglial cell activation process.
Department of Pharmacology, University of Washington, 1959 NE Pacific Way, Seattle, Washington.|Graduate Program in Neurobiology and Behavior, University of Washington, 1959 NE Pacific St., Seattle, Washington.
Susan
S
Fung
Department of Pharmacology, University of Washington, 1959 NE Pacific Way, Seattle, Washington.
Allison E
AE
Cherry
Department of Pharmacology, University of Washington, 1959 NE Pacific Way, Seattle, Washington.
Cong
C
Xu
Department of Pharmacology, University of Washington, 1959 NE Pacific Way, Seattle, Washington.|Graduate Program in Neurobiology and Behavior, University of Washington, 1959 NE Pacific St., Seattle, Washington.|Department of Psychiatry and Behavioral Sciences, University of Washington, 1959 NE Pacific Way, Seattle, Washington.
Nephi
N
Stella
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D048588:Benzoxazines / Q000494:pharmacology; D001921:Brain / Q000166:cytology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D049109:Cell Proliferation / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D054357:Chemokine CXCL10 / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D016207:Cytokines / Q000494:pharmacology; D013759:Dronabinol / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000187:drug effects / Q000502:physiology*; D009025:Morpholines / Q000494:pharmacology; D009281:Naphthalenes / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*
D048588:Benzoxazines; D002121:Calcium Channel Blockers; D054357:Chemokine CXCL10; D016207:Cytokines; D009025:Morpholines; D009281:Naphthalenes; D043562:Receptors, G-Protein-Coupled; D009569:Nitric Oxide; C070417:(3R)-((2,3-dihydro-5-methyl-3-((4-morpholinyl)methyl)pyrrolo-(1,2,3-de)-1,4-benzoxazin-6-yl)(1-naphthalenyl))methanone; D013759:Dronabinol; D000255:Adenosine Triphosphate; D000242:Cyclic AMP
GPCR; cannabinoid; cell migration and cell proliferation; microglia