The Journal of Neuroscience, November 15, 1998, 18(22):9386-9393
Novel Domain-Specific Actions of Amyloid Precursor Protein on
Developing Synapses
Takako
Morimoto,
Ikuroh
Ohsawa,
Chizuko
Takamura,
Mariko
Ishiguro,
Yasuko
Nakamura, and
Shinichi
Kohsaka
Department of Neurochemistry, National Institute of Neuroscience,
Kodaira, Tokyo 187-8502, Japan
The effect of the secretory form of amyloid precursor protein
(sAPP) on synaptic transmission was examined by using developing neuromuscular synapses in Xenopus cell cultures. The
frequency of spontaneous postsynaptic currents (SSCs) was reduced by
the addition of sAPP, whereas the amplitude of impulse-evoked
postsynaptic currents (ESCs) was increased by sAPP. These opposing
effects on spontaneous versus evoked release were separated by using
the specific domain of APP. The C-terminal fragment of sAPP (CAPP) only
reduced SSC frequency and did not affect ESCs. By contrast, the
N-terminal fragment of sAPP (NAPP) did not affect SSC frequency but did
increase ESC amplitude. The reduction of SSC frequency by sAPP appears
to be mediated by activation of potassium channels through a
cGMP-dependent pathway, whereas the increase of ESC amplitude is
mediated by a different pathway involving activation of protein
kinase(s). These results suggest the potential role of sAPP as a
modulator of synaptic activity by two specific domains.
Key words:
amyloid precursor protein; spontaneous synaptic currents; evoked synaptic currents; domain-specific; modulator; synaptic
activity; developing synapses
Copyright © 1998 Society for Neuroscience 0270-6474/98/18229386-08$05.00/0