PT  - JOURNAL ARTICLE
AU  - Hyungju Park
AU  - Jin-A Lee
AU  - Changhoon Lee
AU  - Min-Jeong Kim
AU  - Deok-Jin Chang
AU  - Hyoung Kim
AU  - Seung-Hee Lee
AU  - Yong-Seok Lee
AU  - Bong-Kiun Kaang
TI  - An &lt;em&gt;Aplysia&lt;/em&gt; Type 4 Phosphodiesterase Homolog Localizes at the Presynaptic Terminals of &lt;em&gt;Aplysia&lt;/em&gt; Neuron and Regulates Synaptic Facilitation
AID  - 10.1523/JNEUROSCI.1989-05.2005
DP  - 2005 Sep 28
TA  - The Journal of Neuroscience
PG  - 9037--9045
VI  - 25
IP  - 39
4099  - http://www.jneurosci.org/content/25/39/9037.short
4100  - http://www.jneurosci.org/content/25/39/9037.full
SO  - J. Neurosci.2005 Sep 28; 25
AB  - The cAMP-dependent signaling pathway is critically involved in memory-related synaptic plasticity. cAMP-specific type 4 phosphodiesterases (PDE4) play a role in this process by regulating the cAMP concentration. However, it is unclear how PDE4 is involved in regulating synaptic plasticity. To address this issue in Aplysia sensory-to-motor synapses, we identified a long isoform of the PDE4 homolog in Aplysia kurodai (apPDE), with genetic and biochemical properties similar to those of mammalian PDE4s. Furthermore, apPDE is localized to the membrane and presynaptic region. Both apPDE overexpression and knock-down impaired short- and long-term facilitation, indicating that an appropriate expression level of apPDE in synaptic regions is required for normal synaptic facilitation. By using fluorescence resonance energy transfer-based measurement of in vivo protein kinase A (PKA) activation, we found that the PKA activation by 5-hydroxytryptamine (5-HT) was impaired in both apPDE-overexpressed and knock-down synapses. Analogous to the inhibition of apPDE by RNA interference, chronic rolipram treatment before 5-HT stimulation also impaired the PKA activation by 5-HT, suggesting that regulation of the synaptic cAMP level by PDE4 is critical for normal synaptic facilitation. Together, we suggest that PDE4s localized in the synapses play a critical role in regulating the optimum cAMP level required for normal synaptic plasticity.