Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

Phosphoinositide 3-kinase and its downstream effector kinase PKB/Akt have been suggested to have crucial roles in suppressing apoptosis in several classes of neurons. However, few studies have conducted a long-term investigation of either kinase activity, many studies relying instead on use of the phosphoinositide 3-kinase inhibitors wortmannin and LY294002. When we added LY294002 or wortmannin to sympathetic neurons, apoptosis in the presence of nerve growth factor (NGF) was very slow compared to that obtained by NGF deprivation. However, expression of a kinase-inactive mutant of PKB/Akt in the presence of NGF induced apoptosis in a significant proportion of the neurons. To understand this discrepancy, we investigated more closely the regulation of PKB/Akt activity by NGF. NGF stimulation induced a rapid increase in PKB/Akt activity which was sustained at approximately 6-fold up to 24 h. Phosphoinositide 3-kinase was also rapidly activated by NGF. However, concentrations of wortmannin which completely blocked phosphoinositide 3-kinase activity in the neurons inhibited no more than 50-70% of cellular PKB/Akt activity. Similarly, approximately 50% of maximal NGF-stimulated PKB/Akt activity remained elevated at concentrations of LY294002 which completely blocked neurite outgrowth, a process known to be phosphoinositide 3-kinase dependent. We suggest that a proportion of the sustained PKB/Akt activity induced by NGF is mediated by phosphoinositide 3-kinase-independent pathways. These results raise a cautionary note as to the usefulness of LY294002 or wortmannin as tools to dissect the role of PKB/Akt in neuronal survival.


Journal article


Brain Res

Publication Date





127 - 142


Androstadienes, Animals, Apoptosis, Cells, Cultured, Chromones, Enzyme Inhibitors, Kinetics, Morpholines, Nerve Growth Factors, Neurites, Neurons, Phosphatidylinositol 3-Kinases, Protein-Serine-Threonine Kinases, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-akt, Rats, Recombinant Proteins, Signal Transduction, Superior Cervical Ganglion, Transfection