Neutral sphingomyelinase 2 induces dopamine uptake through regulation of intracellular calcium.
Ceramide serves as a second messenger produced from sphingomyelin by the activation of sphingomyelinase (SMase). Here, we suggest that neutral SMase 2 (nSMase2) may regulate dopamine (DA) uptake. nSMase2 siRNA-transfected PC12 cells showed lower levels of nSMase activity and ceramide than scramble siRNA-transfected and control cells. Interestingly, transfection of nSMase2 siRNA or pretreatment with the nSMase2-specific inhibitor GW4869 resulted in decreased DA uptake. Reciprocally, exposure of PC12 cells to cell-permeable C(6)-ceramide induced a concentration-dependent increase in DA uptake. Removal of extracellular calcium by EGTA increased DA uptake in scramble-transfected and control cells, but not in nSMase2 siRNA-transfected or GW4869-pretreated cells. Moreover, siRNA-transfected cells showed higher levels of intracellular calcium than scramble cells, while C(6)-ceramide treatment resulted in decreased intracellular calcium compared to vehicle treatment alone. Taken together, these data suggest that nSMase2 may increase DA uptake through inducing ceramide production and thereby decreasing intracellular calcium levels.
Kim
Seok Kyun
SK
Department of Environmental & Health Chemistry, Chung-Ang University, Dongjak-Ku, Seoul, South Korea.
Ahn
Kyong Hoon
KH
Ji
Jung Eun
JE
Choi
Jong Min
JM
Jeon
Hyung Jun
HJ
Jung
Sung Yun
SY
Jung
Kwang Mook
KM
Kim
Dae Kyong
DK
D000814:Aniline Compounds / Q000494:pharmacology; D000818:Animals; D001597:Benzylidene Compounds / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects; D002463:Cell Membrane Permeability / Q000187:drug effects; D002518:Ceramides / Q000096:biosynthesis; D004298:Dopamine / Q000378:metabolism*; D004533:Egtazic Acid / Q000494:pharmacology; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism*; D020932:Nerve Growth Factor / Q000494:pharmacology; D016716:PC12 Cells; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism*; D014162:Transfection
D000814:Aniline Compounds; D001597:Benzylidene Compounds; D002518:Ceramides; C468773:GW 4869; D034741:RNA, Small Interfering; D004533:Egtazic Acid; D020932:Nerve Growth Factor; C107180:Smpd3 protein, rat; D013108:Sphingomyelin Phosphodiesterase; D002118:Calcium; D004298:Dopamine