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K-252b selectively potentiates cellular actions and trk tyrosine phosphorylation mediated by neurotrophin-3
B Knüsel1, D R Kaplan, J W Winslow
1Department of Biological Sciences, University of Southern California, Los Angeles 90089.
Abstract:
K-252b, a protein kinase inhibitor, has been shown earlier to inhibit nerve growth factor actions on cholinergic neurons of the basal forebrain. In the present study, K-252b was found to prevent trophic actions of two other neurotrophins, brain-derived neurotrophic factor, and neurotrophin-3, on central cholinergic and dopaminergic neurons, peripheral sensory neurons, and PC12 pheochromocytoma cells, when used at greater than 2 microM concentration. Comparable actions of nonneurotrophin growth factors were not affected. Surprisingly, at 0.1-100 nM, K-252b selectively enhanced the trophic action of neurotrophin-3 on central cholinergic neurons, peripheral sensory neurons, and PC12 cells. In PC12 cells, K-252b potentiated the neurotrophin-3-induced tyrosine phosphorylation of trk, a protein kinase responsible for transmitting neurotrophin signals. Of the three structurally related nerve growth factor inhibitors, K-252a, K-252b, and staurosporine, only the first two also mediated neurotrophin-3 potentiation. These findings indicate that K-252b generally and selectively potentiates the neurotrophic action of neurotrophin-3 and suggest that this action involves trk-type neurotrophin receptors.
Insights
K-252b, a protein kinase inhibitor, can block neurotrophin actions at high concentrations but selectively enhances neurotrophin-3
Area of Science:
- Neuroscience
- Molecular Biology
- Cell Biology
Background:
- K-252b is a known inhibitor of nerve growth factor (NGF) actions.
- Neurotrophins are crucial for neuronal survival and function.
- Understanding neurotrophin signaling is key to developing treatments for neurological disorders.
Purpose of the Study:
- To investigate the effects of K-252b on the actions of brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3).
- To determine the concentration-dependent effects of K-252b on neurotrophin signaling.
- To elucidate the role of K-252b in neurotrophin-3 potentiation and its underlying mechanisms.
Main Methods:
- Treatment of various neuronal cells (central cholinergic, dopaminergic, peripheral sensory, PC12 pheochromocytoma cells) with K-252b and neurotrophins.
- Assessing the trophic actions of neurotrophins.
- Measuring tyrosine phosphorylation of Trk receptors in PC12 cells.
- Comparing the effects of K-252a, K-252b, and staurosporine.
Main Results:
- K-252b ( > 2 microM) inhibited trophic actions of BDNF and NT-3 on multiple neuronal types.
- K-252b (0.1-100 nM) selectively enhanced NT-3's trophic action on central cholinergic neurons, peripheral sensory neurons, and PC12 cells.
- K-252b potentiated NT-3-induced Trk receptor tyrosine phosphorylation in PC12 cells.
- K-252a and K-252b, but not staurosporine, potentiated NT-3 actions.
Conclusions:
- K-252b exhibits dual concentration-dependent effects on neurotrophin actions, inhibiting at high concentrations and potentiating NT-3 at low concentrations.
- The selective potentiation of NT-3 by K-252b suggests a specific interaction with Trk-type neurotrophin receptors.
- These findings highlight K-252b as a valuable tool for studying neurotrophin signaling, particularly NT-3 pathways.