Differences in survival-promoting effects and intracellular signaling properties of BDNF and IGF-1 in cultured cerebral cortical neurons.
Brain-derived neurotrophic factor (BDNF) and insulin-like growth factor-1 (IGF-1) act on various neurons of the CNS as neurotrophic factors promoting neuronal differentiation and survival. We examined the survival-promoting effects of BDNF and IGF-1 on serum deprivation-induced death in cultured cerebral cortical neurons, and compared the intracellular signaling pathways stimulated by BDNF and IGF-1 in the neurons. We found that the survival-promoting effect of BDNF was much weaker than that of IGF-1 in serum deprivation-induced death of cultured cortical neurons. We found no differences in the levels of phosphatidylinositol 3-kinase (PtdIns3-K) activity or Akt (also called PKB) phosphorylation induced by BDNF and IGF-1 in the cultured cortical neurons, although many reports suggest that PtdIns3-K and Akt are involved in survival promotion. In addition, phosphorylation signals of mitogen-activated protein kinase (MAPK) and cAMP responsive element-binding protein (CREB), which have also been reported to be involved in survival promotion, were stimulated by BDNF much more potently than by IGF-1. These results show that there may be, as yet unidentified, intracellular signaling pathways other than the PtdIns3-K-Akt, MAPK and CREB signaling, to regulate survival promotion. These unidentified signaling pathways may be responsible for the distinct strengths of the survival-promoting effects of BDNF and IGF-1.
Yamada
M
M
Institute for Protein Research, Osaka University, Osaka, Japan. yamada@protein.osaka-u.ac.jp
Tanabe
K
K
Wada
K
K
Shimoke
K
K
Ishikawa
Y
Y
Ikeuchi
T
T
Koizumi
S
S
Hatanaka
H
H
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D019208:Brain-Derived Neurotrophic Factor / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D005260:Female; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D008297:Male; D009474:Neurons / Q000166:cytology* / Q000187:drug effects* / Q000201:enzymology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D017208:Rats, Wistar; D019061:src-Family Kinases / Q000378:metabolism
D019208:Brain-Derived Neurotrophic Factor; D017362:Cyclic AMP Response Element-Binding Protein; D007334:Insulin-Like Growth Factor I; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D019061:src-Family Kinases; C494920:Akt1 protein, rat