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Suppression of long-term facilitation by Rab3-effector protein interaction
Jin-Hee Han1, Changhoon Lee, Yehwang Cheang
1National Research Laboratory of Neurobiology, Institute of Molecular Biology and Genetics, School of Biological Sciences, College of Natural Sciences, Seoul National University, San 56-1 Silim-dong Kwanak-gu, Seoul 151-742, South Korea.
Brain Research. Molecular Brain Research
|June 7, 2005
Summary
Aplysia long-term facilitation (LTF) is inhibited by Rab3, a neuronal protein. Rab3 likely acts as a negative clamp on LTF by interacting with effector proteins like Rim.
Area of Science:
- Neuroscience
- Cell Biology
- Molecular Biology
Background:
- Long-term facilitation (LTF) in Aplysia involves presynaptic release modulation.
- The precise mechanisms regulating synaptic vesicle release during LTF are not fully understood.
- Rab3, a neuronal GTP-binding protein, is a known regulator of synaptic vesicle fusion.
Purpose of the Study:
- To investigate the role of Rab3 in the molecular mechanisms underlying LTF in Aplysia.
- To determine if Rab3 modulates synaptic vesicle release during LTF.
Main Methods:
- Overexpression of wild-type Aplysia Rab3 (apRab3) and its mutant forms in Aplysia neurons.
- Assessment of the effects of apRab3 variants on LTF.
- Analysis of apRab3 interactions with effector molecules like Rim and Rabphilin.
Main Results:
- Overexpression of wild-type apRab3 or a constitutively active mutant (apRab3 Q80L) completely inhibited LTF.
- A double mutant (apRab3 Q80L, V54E) unable to bind effectors like Rim or Rabphilin did not affect LTF.
- A triple mutant (apRab3 Q80L, F18L, D19E) with reduced Rim binding enhanced basal release and occluded LTF.
Conclusions:
- Aplysia Rab3 (apRab3) acts as a negative regulator of LTF.
- apRab3 likely exerts its inhibitory effect through interaction with effector proteins, potentially Rim.
- These findings elucidate a novel mechanism controlling synaptic plasticity in Aplysia.