Lysosphingomyelin-elicited Ca2+ mobilization from rat brain microsomes.
We have examined the Ca2+ release activity of sphingolipid-derivatives from rat brain microsomes using a Fura-2 cytofluorometric assay. Sphingosylphosphorylcholine, lysosphingomyelin, elicited a rapid Ca2+ release from both cerebral and cerebellar microsomes. Other compounds including sphingosine and sphingosine-1-phosphate were incapable of causing the Ca2+ release. The pharmacological properties suggest that the sphingosylphosphorylcholine-elicited Ca2+ mobilization is not mediated by inositol 1,4,5-triphosphate receptors. Immunocytochemical study showed the occurrence of sphingomyelin, a putative precursor for sphingosylphosphorylcholine, in the somatodendritic membrane domains of cerebellar neurons. These observations imply that sphingosylphosphorylcholine is a potent Ca2+ releaser in brain neurons.
Laboratory for Cellular Glycobiology, Institute of Physical and Chemical Research (RIKEN), Saitama, Japan. furuyash@postman.riken.go.jp
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Furuya
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Kurono
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Hirabayashi
D000818:Animals; D001921:Brain / Q000378:metabolism* / Q000648:ultrastructure; D002118:Calcium / Q000378:metabolism*; D005456:Fluorescent Dyes; D016257:Fura-2; D017136:Ion Transport / Q000187:drug effects; D008861:Microsomes / Q000378:metabolism*; D010767:Phosphorylcholine / Q000031:analogs & derivatives* / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology
D005456:Fluorescent Dyes; C005356:sphingosine phosphorylcholine; D010767:Phosphorylcholine; D013110:Sphingosine; D002118:Calcium; D016257:Fura-2