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Modulation of olfactory bulb neuron potassium current by tyrosine phosphorylation
1Biochemistry Department and Volen Center for Complex Systems, Brandeis University, Waltham, Massachusetts 02254, USA.
Summary
Insulin suppresses neuronal potassium currents by affecting Kv1.3 channels. This process involves tyrosine phosphorylation, with distinct residues mediating suppression by insulin and pervanadate.
Area of Science:
- Neuroscience
- Molecular Biology
- Biochemistry
Background:
- Voltage-dependent outward currents in olfactory bulb neurons are modulated by insulin.
- The C-type inactivation properties suggest involvement of Kv1.3 potassium channels.
- Kv1.3 channels are identified as prominent in cultured olfactory bulb neurons.
Purpose of the Study:
- To investigate the molecular mechanisms underlying insulin-induced suppression of neuronal potassium currents.
- To identify specific tyrosine residues in Kv1.3 channels critical for modulation by insulin and pervanadate.
Main Methods:
- Whole-cell patch-clamp electrophysiology on cultured rat olfactory bulb neurons.
- Expression of wild-type and mutant Kv1.3 channels in HEK 293 cells.
- Treatment with insulin, pervanadate, and margatoxin; immunocytochemistry and tyrosine phosphorylation analysis.
Main Results:
- Insulin and pervanadate suppressed whole-cell outward currents in olfactory bulb neurons.
- Kv1.3 channels are implicated, as margatoxin blocked most of the current.
- Mutational analysis revealed distinct tyrosine residues required for pervanadate and insulin-mediated suppression of Kv1.3 current.
- Insulin stimulated tyrosine phosphorylation of Kv1.3 channels.
Conclusions:
- Kv1.3 channels are key targets for insulin-mediated modulation of neuronal potassium currents.
- Complex phosphorylation patterns involving specific tyrosine residues regulate Kv1.3 channel activity.
- Both receptor and nonreceptor tyrosine kinases likely contribute to this regulation.