TY - JOUR
T1 - Differential inhibition of nerve growth factor responses by purine analogues
T2 - Correlation with inhibiton of a nerve growth factor-activated protein kinase
AU - Volonte, C.
AU - Rukenstein, A.
AU - Loeb, D. M.
AU - Greene, L. A.
PY - 1989
Y1 - 1989
N2 - Purine analogues were used in this study to dissect specific steps in the mechanism of action of nerve growth factor (NGF). Protein kinase N (PKN) is an NGF-activated serine protein kinase that is active in the presence of Mn++. The activity of PKN was inhibited in vitro by purine analogues, the most effective of which was 6-thioguanine (apparent K(i) = 6 μM). Several different criteria indicated that 6-thioguanine is not a general inhibitor of protein kinases and that it is relatively specific for PKN. For instance, it did not affect protein kinases A or C and was without effect on the overall level and pattern of protein phosphorylation by either intact or broken PC12 cells. Since purine analogues rapidly and effectively enter cells, they were also assessed for their actions on both transcription-dependent and -independent responses of PC12 cells to NGF. NGF-promoted neurite regeneration was reversibly suppressed by the analogues and at concentrations very similar to those that inhibit PKN. Comparable concentrations of the analogues also blocked NGF-stimulated induction of ornithine decarboxylase activity. In contrast to its inhibition of neurite regeneration and ornithine decarboxylase induction, 6-thioguanine did not suppress NGF-dependent induction of c-fos mRNA expression. Thus, purine analogues such as 6-thioguanine appear capable of differentially suppressing some, but not other actions of NGF. These findings suggest the presence of multiple pathways in the NGF mechanism and that these can be dissected with purine analogues. Moreover, these data are compatible with a role for protein kinase N in certain of these pathways.
AB - Purine analogues were used in this study to dissect specific steps in the mechanism of action of nerve growth factor (NGF). Protein kinase N (PKN) is an NGF-activated serine protein kinase that is active in the presence of Mn++. The activity of PKN was inhibited in vitro by purine analogues, the most effective of which was 6-thioguanine (apparent K(i) = 6 μM). Several different criteria indicated that 6-thioguanine is not a general inhibitor of protein kinases and that it is relatively specific for PKN. For instance, it did not affect protein kinases A or C and was without effect on the overall level and pattern of protein phosphorylation by either intact or broken PC12 cells. Since purine analogues rapidly and effectively enter cells, they were also assessed for their actions on both transcription-dependent and -independent responses of PC12 cells to NGF. NGF-promoted neurite regeneration was reversibly suppressed by the analogues and at concentrations very similar to those that inhibit PKN. Comparable concentrations of the analogues also blocked NGF-stimulated induction of ornithine decarboxylase activity. In contrast to its inhibition of neurite regeneration and ornithine decarboxylase induction, 6-thioguanine did not suppress NGF-dependent induction of c-fos mRNA expression. Thus, purine analogues such as 6-thioguanine appear capable of differentially suppressing some, but not other actions of NGF. These findings suggest the presence of multiple pathways in the NGF mechanism and that these can be dissected with purine analogues. Moreover, these data are compatible with a role for protein kinase N in certain of these pathways.
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U2 - 10.1083/jcb.109.5.2395
DO - 10.1083/jcb.109.5.2395
M3 - Article
C2 - 2553745
AN - SCOPUS:0024425111
SN - 0021-9525
VL - 109
SP - 2395
EP - 2403
JO - Journal of Cell Biology
JF - Journal of Cell Biology
IS - 5
ER -