Volume 17, Number 15,
Issue of August 1, 1997
pp. 5792-5797
Copyright ©1997 Society for Neuroscience
Requirement for Tyrosine Phosphatase during Serotonergic
Neuromodulation by Protein Kinase C
Received March 7, 1997; revised May 6, 1997; accepted May 20, 1997.
Stefano Catarsi and
Pierre Drapeau
Centre for Research in Neuroscience, McGill University, and
Montreal General Hospital Research Institute, Montreal, Quebec, Canada
H3G 1A4
Tyrosine kinases and phosphatases are abundant in the nervous
system, where they signal cellular differentiation, mediate the
responses to growth factors, and direct neurite outgrowth during
development. Tyrosine phosphorylation can also alter ion channel
activity, but its physiological significance remains unclear. In an
identified leech mechanosensory neuron, the ubiquitous neuromodulator serotonin increases the activity of a cation channel by activating protein kinase C (PKC), resulting in membrane depolarization and modulation of the receptive field properties. We observed that the
effects on isolated neurons and channels were blocked by inhibiting tyrosine phosphatases. Serotonergic stimulation of PKC thus activates a
tyrosine phosphatase activity associated with the channels, which
reverses their constitutive inhibition by tyrosine phosphorylation, representing a novel form of neuromodulation.
Key words:
single channel;
serotonin;
protein kinase C;
tyrosine
phosphorylation;
identified neuron;
leech