Partitioning of the serotonin transporter into lipid microdomains modulates transport of serotonin.
The serotonin transporter (SERT) is an integral membrane protein responsible for the clearance of serotonin from the synaptic cleft following the release of the neurotransmitter. SERT plays a prominent role in the regulation of serotoninergic neurotransmission and is a molecular target for multiple antidepressants as well as substances of abuse. Here we show that SERT associates with lipid rafts in both heterologous expression systems and rat brain and that the inclusion of the transporter into lipid microdomains is critical for serotonin uptake activity. SERT is present in a subpopulation of lipid rafts, which is soluble in Triton X-100 but insoluble in other non-ionic detergents such as Brij 58. Disaggregation of lipid rafts upon depletion of cellular cholesterol results in a decrease of serotonin transport capacity (V(max)), due to the reduction of turnover number of serotonin transport. Our data suggest that the association of SERT with lipid rafts may represent a mechanism for regulating the transporter activity and, consequently, serotoninergic signaling in the central nervous system, through the modulation of the cholesterol content in the cell membrane. Furthermore, SERT-containing rafts are detected in both intracellular and cell surface fractions, suggesting that raft association may be important for trafficking and targeting of SERT.
Magnani
Francesca
F
Department of Biochemistry, Trinity College, Dublin 2, Ireland.
Tate
Christopher G
CG
Wynne
Samantha
S
Williams
Clive
C
Haase
Jana
J
D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry; D001692:Biological Transport; D019921:Biotinylation; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002490:Central Nervous System / Q000378:metabolism; D002592:Cetomacrogol / Q000494:pharmacology; D002784:Cholesterol / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D003902:Detergents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007700:Kinetics; D008055:Lipids / Q000737:chemistry; D008562:Membrane Glycoproteins / Q000737:chemistry*; D021962:Membrane Microdomains / Q000378:metabolism*; D026901:Membrane Transport Proteins; D008856:Microscopy, Fluorescence; D009419:Nerve Tissue Proteins / Q000737:chemistry*; D017830:Octoxynol / Q000494:pharmacology; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism*; D050486:Serotonin Plasma Membrane Transport Proteins; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000378:metabolism
D000911:Antibodies, Monoclonal; D002352:Carrier Proteins; D018076:DNA, Complementary; D003902:Detergents; D008055:Lipids; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins; C493232:Slc6a4 protein, rat; D012701:Serotonin; D017830:Octoxynol; D002592:Cetomacrogol; D002784:Cholesterol