Sphingosine and Its Analog, the Immunosuppressant 2-Amino-2-(2-[4-octylphenyl]ethyl)-1,3-propanediol, Interact with the CB₁ Cannabinoid Receptor

Abstract

Sphingosine-1-phosphate (S1P) and cannabinoid receptors are G-protein-coupled receptors that mediate the effects of S1P and endocannabinoids, respectively. Cannabinoid receptors also mediate the effects of ⌬ 9 -tetrahydrocannabinol, the primary psychoactive ingredient in marijuana, whereas S1P receptors contribute to the immunosuppressant effects of 2-amino-2-(2-[4-octylphenyl]ethyl)-1,3-propanediol (FTY720). FTY720 is a sphingosine analog that can prevent renal graft rejections and suppress a variety of autoimmune disorders in animal models and clinical trials. We now report that both FTY720 and sphingosine interact with CB 1 but not CB 2 cannabinoid receptors. FTY720 and sphingosine inhibited the binding of the CB 1 -selective antagonist -2) in a concentration-dependent manner, and this antagonist effect was not mimicked by S1P. FTY720 and sphingosine also inhibited activation of extracellular signal-regulated kinases 1 and 2 and Akt by WIN55,212-2 in intact Chinese hamster ovary (CHO) cells expressing CB 1 receptors and attenuated WIN55,212-2-stimulated internalization of a fluorescence-tagged CB 1 receptor in CHO cells. Moreover, both FTY720 and sphingosine produced rightward shifts in the concentration-effect curves of cannabinoid agonists for G-protein activation, indicating that they act as competitive CB 1 antagonists. These results suggest that the CB 1 receptor could be a novel target of FTY720 and that sphingosine could be an endogenous CB 1 antagonist.Sphingosine-1-phosphate (S1P) and cannabinoid receptors belong to the lysolipid family of GPCRs (Toman and Spiegel, 2002). Subtypes for each receptor, S1P 1-5 and CB 1 and CB 2 , have been identified and exhibit unique tissue distributions and functional profiles. There are a number of similarities between S1P and cannabinoid receptors with a notably significant sequence homology of approximately 35% (Toman and Spiegel, 2002). S1P and cannabinoid receptors are actiThese studies were supported by National Institutes of Health grants DA05274, DA14277, and GM43880. Imaging was supported in part by National Institutes of Health grant P30-CA16059.A preliminary version of this work was presented previously in abstract form: Selley DE, Cassidy MP, Milstein S, He HJ, Sim-Selley LJ, Spiegel S, and Paugh SW. ABBREVIATIONS: S1P, sphingosine-1-phosphate; BSA, bovine serum albumin; CNS, central nervous system; ERK, extracellular signal regulated kinase; p-, phosphorylated; GPCR, G-protein-coupled receptor; CHO, Chinese hamster ovary; Pen-Strep, penicillin/streptomycin; FBS, fetal bovine serum; DMEM, Dulbecco's modified Eagle's medium; mCB 1 -CHO, Chinese hamster ovary-K1 cells stably expressing the mouse CB 1 receptor; HEK, human embryonic kidney; hCB 1 -HEK, human embryonic kidney-293 cells stably transfected with the human CB 1 receptor; GFP, green fluorescent protein; rCB 1 -GFP, green fluorescent protein-tagged rat CB 1 receptor; GTP␥S, guanosine

Inhibition of de novo ceramide biosynthesis by FTY720 protects rat retina from light-induced degeneration

“…Activation of these receptors determines T-cell egression from the lymph node and migration into the blood, responding to an S1P gradient ( 61,62,68 ). However, recent fi ndings showed that FTY720 has a pleotropic effect in cell action and signaling, such as inhibiting ceramide synthesis, inhibiting the cannabinoid CB1 receptor, and inhibiting S1P lyase ( 35,36,69,70 ).…”

Endogenous bioactive lipids and the regulation of conventional outflow facility

“…For example, S1P has been shown to stimulate COX-2 expression in vascular smooth muscle cells, which controls the generation of prostaglandins [134]. Moreover, recent studies report that S1P binds to CB1 cannabinoid receptors, acting as a competitive antagonist [135]. Since anadamide and S1P produce the opposite effects on actin organization and outflow facility, unknown is whether S1P reduces outflow facility via stimulating S1P receptors or via antagonizing CB1 receptors.…”

Sphingosine-1–Phosphate, FTY720, and Sphingosine-1–Phosphate Receptors in the Pathobiology of Acute Lung Injury

“…GPCRs comprise a large and diverse family of receptors with varying homologies to the S1P receptors that could potentially participate in transducing FTY720 responses (76). For example, FTY720 interacts with the cannabinoid family of GPCRs (77), but the primary cannabinoid receptors, CB 1 and CB 2 , are not involved in the EC barrier-enhancing response (70). In addition, FTY720 (but not S1P) inhibits S1PL (78), cytosolic phospholipase A 2 (79), and ceramide synthases (80,81), and activates protein phosphatase 2A (82).…”