Diacylglycerol and ceramide formation induced by dopamine D2S receptors via Gbeta gamma -subunits in Balb/c-3T3 cells.
Diacylglycerol (DAG) and ceramide are important second messengers affecting cell growth, differentiation, and apoptosis. Balb/c-3T3 fibroblast cells expressing dopamine-D2S (short) receptors (Balb-D2S cells) provide a model of G protein-mediated cell growth and transformation. In Balb-D2S cells, apomorphine (EC(50) = 10 nM) stimulated DAG and ceramide formation by 5.6- and 4.3-fold, respectively, maximal at 1 h and persisting over 6 h. These actions were blocked by pretreatment with pertussis toxin (PTX), implicating G(i)/G(o) proteins. To address which G proteins are involved, Balb-D2S clones expressing individual PTX-insensitive Galpha(i) proteins were treated with PTX and tested for apomorphine-induced responses. Neither PTX-insensitive Galpha(i2) nor Galpha(i3) rescued D2S-induced DAG or ceramide formation. Both D2S-induced DAG and ceramide signals required Gbetagamma-subunits and were blocked by inhibitors of phospholipase C [1-(6-[([17beta]-3-methoxyestra-1,2,3[10]-trien- 17yl)amino]hexyl)-1H-pyrrole-2,5-dione (U-73122) and partially by D609]. The similar G protein specificity of D2S-induced calcium mobilization, DAG, and ceramide formation indicates a common Gbetagamma-dependent phospholipase C-mediated pathway. Both D2 agonists and ceramide specifically induced mitogen-activated protein kinase (ERK1/2), suggesting that ceramide mediates a novel pathway of D2S-induced ERK1/2 activation, leading to cell growth.
Liu
Gele
G
Ottawa Health Research Institute (Neuroscience), University of Ottawa, Canada K1H 8M5.
Ghahremani
Mohammad H
MH
Banihashemi
Behzad
B
Albert
Paul R
PR
D016475:3T3 Cells; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D002518:Ceramides / Q000378:metabolism*; D004075:Diglycerides / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005057:Eukaryotic Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051960:GTP-Binding Protein alpha Subunit, Gi2; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000187:drug effects / Q000378:metabolism; D020962:Heterotrimeric GTP-Binding Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism; D037342:Pertussis Toxin; D011518:Proto-Oncogene Proteins / Q000187:drug effects / Q000378:metabolism; D017448:Receptors, Dopamine D2 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D015290:Second Messenger Systems / Q000187:drug effects / Q000235:genetics*; D010738:Type C Phospholipases / Q000187:drug effects / Q000378:metabolism
D002518:Ceramides; D004075:Diglycerides; D011518:Proto-Oncogene Proteins; D017448:Receptors, Dopamine D2; D037342:Pertussis Toxin; D020928:Mitogen-Activated Protein Kinases; D010738:Type C Phospholipases; D051960:GTP-Binding Protein alpha Subunit, Gi2; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; C498016:Gnai2 protein, mouse; D020962:Heterotrimeric GTP-Binding Proteins; D001058:Apomorphine