Anandamide induces cell death independently of cannabinoid receptors or vanilloid receptor 1: possible involvement of lipid rafts.
Anandamide triggers various cellular activities by binding to cannabinoid (CB1/CB2) receptors or vanilloid receptor 1 (VR1). However, the role of these receptors in anandamide-induced apoptosis remains largely unknown. Here, we show that SR141716A, a specific inhibitor of cannabinoid receptor (CB1-R), did not block anandamide-induced cell death in endogenously CB1-R expressing cells. In addition, CB1-R-lacking Chinese hamster ovary (CHO) cells underwent cell death after anandamide treatment. SR144528, a specific inhibitor of CB2-R also failed to block anandamide-induced cell death in HL-60 cells. Capsazepine, a specific antagonist of VR1 could not prevent anandamide-induced cell death in constitutively and endogenously VR1 expressing PC12 cells. Moreover, anandamide noticeably triggered cell death in VR1-lacking human embryonic kidney (HEK) cells. In contrast, methyl-beta cyclodextrin (MCD), a membrane cholesterol depletor, completely blocked anandamide-induced cell death in a variety of cells, including PC12, C6, Neuro-2a, CHO, HEK, SMC, Jurkat and HL-60 cells. MCD also blocked anandamide-induced superoxide generation, phosphatidyl serine exposure and p38 MAPK/JNK activation. Thus, our data imply a novel role for of membrane lipid rafts in anandamide-induced cell death.
Sarker
K P
KP
Department of Laboratory and Molecular Medicine, Faculty of Medicine, Kagoshima University, Kagoshima 890, Japan. kpsarker@ucalgary.ca
Maruyama
I
I
D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D001095:Arachidonic Acids / Q000378:metabolism / Q000494:pharmacology*; D001483:Base Sequence; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D003505:Cyclodextrins / Q000494:pharmacology; D018076:DNA, Complementary / Q000235:genetics; D063388:Endocannabinoids; D018922:HL-60 Cells; D006801:Humans; D019169:Jurkat Cells; D021962:Membrane Microdomains / Q000378:metabolism; D008954:Models, Biological; D016716:PC12 Cells; D053284:Polyunsaturated Alkamides; D051381:Rats; D043885:Receptor, Cannabinoid, CB2; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D047392:beta-Cyclodextrins
D001095:Arachidonic Acids; C469526:Cnr2 protein, rat; D003505:Cyclodextrins; D018076:DNA, Complementary; D063388:Endocannabinoids; D053284:Polyunsaturated Alkamides; D043885:Receptor, Cannabinoid, CB2; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; C078814:anandamide