Abstract
Activation of presynaptic cAMP-dependent protein kinase A (PKA) triggers presynaptic long-term plasticity in synapses such as cerebellar parallel fiber and hippocampal mossy fiber synapses. RIM1α, a large multidomain protein that forms a scaffold at the presynaptic active zone, is essential for presynaptic long-term plasticity in these synapses and is phosphorylated by PKA at serine-413. Previous studies suggested that phosphorylation of RIM1α at serine-413 is required for presynaptic long-term potentiation in parallel fiber synapses formed in vitro by cultured cerebellar neurons and that this type of presynaptic long-term potentiation is mediated by binding of 14-3-3 proteins to phosphorylated serine-413. To test the role of serine-413 phosphorylation in vivo, we have now produced knockin mice in which serine-413 is mutated to alanine. Surprisingly, we find that in these mutant mice, three different forms of presynaptic PKA-dependent long-term plasticity are normal. Furthermore, we observed that in contrast to RIM1αKO mice, RIM1 knockin mice containing the serine-413 substitution exhibit normal learning capabilities. The lack of an effect of the serine-413 mutation of RIM1α is not due to compensation by RIM2α because mice carrying both the serine-413 substitution and a RIM2α deletion still exhibited normal long-term presynaptic plasticity. Thus, phosphorylation of serine-413 of RIM1α is not essential for PKA-dependent long-term presynaptic plasticity in vivo, suggesting that PKA operates by a different mechanism despite the dependence of long-term presynaptic plasticity on RIM1α.
Original language | English (US) |
---|---|
Pages (from-to) | 14680-14685 |
Number of pages | 6 |
Journal | Proceedings of the National Academy of Sciences of the United States of America |
Volume | 105 |
Issue number | 38 |
DOIs | |
State | Published - Sep 23 2008 |
Keywords
- Active zone
- Mossy fiber
- Neurotransmitter release
- Rab3
- Synaptic vesicle
ASJC Scopus subject areas
- General