Preferential activation of microsomal diacylglycerol/protein kinase C signaling during glucose treatment (De Novo phospholipid synthesis) of rat adipocytes.
Glucose has been reported to increase the de novo synthesis of diacylglycerol (DAG) and translocate and activate protein kinase C (PKC) in rat adipocytes. Presently, we examined the major subcellular site of PKC translocation/activation in response to glucose-induced DAG. Glucose rapidly increased DAG content and PKC enzyme activity in microsomes, but not in plasma membranes or other membranes, during a 30-min treatment of rat adipocytes. This glucose-induced increase in microsomal DAG was attended by increases in immunoreactive PKC alpha, beta, and epsilon. Glucose-induced activation of DAG/PKC signaling in microsomes was not associated with a change in the translocation of Glut-4 transporters from microsomes to the plasma membrane, a biological response that is known to be stimulated by agonists, e.g., phorbol esters, which increase DAG/PKC signaling in plasma membranes, as well as in microsomes. In conclusion, an increase in de novo phospholipid synthesis, as occurs during glucose treatment of rat adipocytes, primarily activates DAG/PKC signaling in microsomes; moreover, this signaling response and biological consequences thereof may differ from those of agonists that primarily stimulate DAG/PKC signaling in the plasma membrane.
Farese
R V
RV
James A. Haley Veterans' Hospital, Department of Internal Medicine, University of South Florida, Tampa 33612.
Standaert
M L
ML
Arnold
T P
TP
Yamada
K
K
Musunuru
K
K
Hernandez
H
H
Mischak
H
H
Cooper
D R
DR
D017667:Adipocytes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D004075:Diglycerides / Q000378:metabolism; D004822:Epididymis / Q000166:cytology; D005947:Glucose / Q000494:pharmacology*; D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins; D008566:Membranes / Q000737:chemistry; D008861:Microsomes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D010743:Phospholipids / Q000096:biosynthesis*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction
D004075:Diglycerides; D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes; D008565:Membrane Proteins; D010743:Phospholipids; D011506:Proteins; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D011493:Protein Kinase C; D005947:Glucose