Rapid phosphorylation of phospholipase C gamma 1 by brain-derived neurotrophic factor and neurotrophin-3 in cultures of embryonic rat cortical neurons.
Phospholipase C gamma 1 (PLC-gamma 1) is involved at an early step in signal transduction of many hormones and growth factors and catalyzes the hydrolysis of phosphatidylinositol (PI) 4,5-bisphosphate to diacylglycerol and inositol trisphosphate, two potent intracellular second messenger molecules. The transformation of PC12 cells into neuron-like cells induced by nerve growth factor is preceded by a rapid stimulation of PLC-gamma 1 phosphorylation and PI hydrolysis. The present study analyzed the effects of brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) on phosphorylation of PLC-gamma 1 in primary cultures of embryonic rat brain cells. BDNF and NT-3 stimulated the phosphorylation of PLC-gamma 1, followed by hydrolysis of PI. The stimulation of PLC-gamma 1 phosphorylation occurred within 20 s after addition of BDNF or NT-3 and lasted up to 30 min, with a peak after 4 min. ED50 values were similar for BDNF and NT-3, with approximately 25 ng/ml. Phosphorylation of PLC-gamma 1 by BDNF and NT-3 was found in cultures from all major brain areas. K-252b, a compound known to inhibit selectively neutrophin actions by interfering with the phosphorylation of trk-type neutrophin receptors, prevented the BDNF- and NT-3-stimulated phosphorylation of PLC-gamma 1. Receptors of the trk type were coprecipitated with anti-PLC-gamma 1 antibodies. The presence of trkB mRNA in the cultures was substantiated by northern blot analysis. The action of BDNF and NT-3 seems to be neuron specific because no phosphorylation of PLC-gamma 1 was observed in cultures of nonneuronal brain cells. The results provide evidence that developing neurons of the cerebral cortex and other brain areas are responsive to BDNF and NT-3, and they indicate that the transduction mechanism of BDNF and NT-3 in the brain involves rapid phosphorylation of PLC-gamma 1 followed by PI hydrolysis.
Widmer
H R
HR
Division of Neurogerontology, Ethel Percy Andrus Gerontology Center, University of Southern California, Los Angeles 90089-0191.
Kaplan
D R
DR
Rabin
S J
SJ
Beck
K D
KD
Hefti
F
F
Knüsel
B
B
D000818:Animals; D019208:Brain-Derived Neurotrophic Factor; D002217:Carbachol / Q000494:pharmacology; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000201:enzymology* / Q000378:metabolism; D003342:Corpus Striatum / Q000378:metabolism; D004622:Embryo, Mammalian; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D007700:Kinetics; D008636:Mesencephalon / Q000378:metabolism; D009414:Nerve Growth Factors / Q000494:pharmacology*; D009419:Nerve Tissue Proteins / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects / Q000201:enzymology*; D020933:Neurotrophin 3; D009928:Organ Specificity; D016716:PC12 Cells; D010716:Phosphatidylinositols / Q000378:metabolism*; D010766:Phosphorylation; D011149:Pons / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000494:pharmacology; D010738:Type C Phospholipases / Q000378:metabolism*
D019208:Brain-Derived Neurotrophic Factor; D007527:Isoenzymes; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D020933:Neurotrophin 3; D010716:Phosphatidylinositols; D011994:Recombinant Proteins; D002217:Carbachol; D010738:Type C Phospholipases