Extracellular release of newly synthesized sphingosine‐1‐phosphate by cerebellar granule cells and astrocytes

• Published in: Journal of neurochemistry 2005-03, Vol.92 (5), p.1204-1215
• Main Authors: Anelli, Viviana, Bassi, Rosaria, Tettamanti, Guido, Viani, Paola, Riboni, Laura
• Format: Article
• Language: English
• Subjects: Animals; Animals, Newborn; astrocytes; Astrocytes - drug effects; Astrocytes - metabolism; Autoradiography - methods; Biological and medical sciences; Cell Differentiation - physiology; Cell Membrane - drug effects; Cell Membrane - metabolism; Cells, Cultured; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; cerebellar granule cells; Cerebellum - cytology; Chromatography, Thin Layer - methods; Culture Media, Conditioned - pharmacology; Dose-Response Relationship, Drug; Electrophoresis, Gel, Pulsed-Field - methods; Extracellular Space - metabolism; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation - drug effects; intercellular mediators; Isolated neuron and nerve. Neuroglia; Lysophospholipids - metabolism; Neurons - drug effects; Neurons - metabolism; Phosphotransferases (Alcohol Group Acceptor) - metabolism; Potassium Chloride - pharmacology; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction - methods; RNA, Messenger - biosynthesis; Sphingosine - analogs & derivatives; Sphingosine - metabolism; Sphingosine - pharmacology; sphingosine kinase; sphingosine‐1‐phosphate; Time Factors; Tritium - metabolism; Vertebrates: nervous system and sense organs
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1111/j.1471-4159.2004.02955.x

Sphingosine‐1‐phosphate (S1P) is a potent biomediator that can act as either an intracellular or an intercellular messenger. In the nervous system it exerts a wide range of actions, and specific membrane receptors for it have been identified in various regions. However, the physiological origin of extracellular S1P in the nervous system is largely unknown. We investigated cerebellar granule cells at different stages of differentiation and astrocytes in primary cultures as possible origins of extracellular S1P. Although these cells show marked differences in S1P metabolism, we found that they can all release S1P and express mRNAs for S1P specific receptors. Extracellular S1P derives from the export of newly synthesized intracellular S1P, and not from the action of a released sphingosine kinase. S1P release is rapid, efficient, and can be regulated by exogenous stimuli. Phorbol ester treatment resulted in an increase in sphingosine kinase 1 activity in the membranes, accompanied by a significant increase in extracellular S1P. S1P release in cells from the cerebellum emerges as a regulated mechanism, possibly related to a specific pool of newly synthesized S1P. To our knowledge, this is the first evidence of the extracellular release of S1P by primary cells from the CNS, which supports a role of S1P as autocrine/paracrine physiological messenger in the cerebellum.