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Phosphorylation of synaptic proteins in chick forebrain: changes with development and passive avoidance training
Insights
This study investigated protein phosphorylation in chick brain synapses, finding distinct patterns in synaptic plasma membranes (SPMs) and postsynaptic densities (PSDs) during development and after learning. PSD phosphorylation showed significant developmental changes, suggesting roles in synaptic plasticity.
Area of Science:
- Neuroscience
- Molecular Biology
- Biochemistry
Background:
- Synaptic plasticity underlies learning and memory.
- Protein phosphorylation is a key regulatory mechanism in synaptic function.
- Distinct synaptic fractions, like SPMs and PSDs, have unique molecular compositions.
Purpose of the Study:
- To investigate endogenous protein phosphorylation patterns in synaptic plasma membranes (SPMs) and postsynaptic densities (PSDs) from chick forebrain.
- To examine developmental changes in SPM and PSD phosphorylation.
- To analyze the impact of passive avoidance learning on synaptic protein phosphorylation.
Main Methods:
- Preparation of SPMs and PSDs from chick forebrain using n-octylglucoside extraction.
- In vitro phosphorylation of isolated SPMs and PSDs using [32P]ATP.
- Separation of phosphoproteins via SDS-PAGE and detection by autoradiography and densitometry.
- Comparison of phosphorylation patterns across different developmental stages and behavioral training conditions.
Main Results:
- Phosphate incorporation was observed in several SPM components (52, 37, 29 kDa), but not in similar molecular mass bands within PSD fractions.
- SPM phosphorylation patterns remained consistent during development, while PSD phosphorylation exhibited significant developmental changes.
- Passive avoidance training led to a nonsignificant decrease in the phosphorylation of a 52 kDa SPM band 10 minutes post-training.
Conclusions:
- SPMs and PSDs display differential protein phosphorylation patterns, suggesting distinct roles in synaptic regulation.
- PSD phosphorylation is dynamic and undergoes significant changes during brain development.
- While not statistically significant, the observed decrease in 52 kDa SPM phosphorylation post-training hints at a potential role in learning-related synaptic modifications.
Abstract:
We have used synaptic plasma membranes (SPMs) and postsynaptic densities (PSDs) to study protein phosphorylation at the synapse in the developing chick forebrain and in 1-day-old chick forebrain following training on a passive avoidance task. Endogenous phosphorylation patterns in SPMs and PSDs prepared by extraction with n-octylglucoside isolated from chick forebrain were investigated by labelling with [32P]ATP. The phosphoprotein components of the SPM and PSD fractions were separated using sodium dodecyl sulphate gradient polyacrylamide gel electrophoresis. Autoradiography and densitometry of the Coomassie Blue protein staining pattern revealed phosphate incorporation into several SPM components including those of molecular mass 52, 37, and 29 kilodaltons (kDa). Bands of similar molecular mass were not phosphorylated in PSD fractions. This difference in phosphorylation between SPMs and PSDs was not due to the detergent n-octylglucoside. In a developmental study in which SPM and PSD fractions were prepared from 1-day-old, 14-day-old, and 21-day-old chickens, the phosphorylation patterns of SPMs were similar throughout, but striking differences occurred in PSDs, both in the level of phosphorylation and in the components phosphorylated. A time-course study was carried out in which phosphorylation of SPMs and PSDs from 1-day-old chicks trained on a passive avoidance task was compared with patterns from control chicks trained on a water-coated bead and untrained chicks. In SPMs prepared from forebrains removed 10 mins following training, a consistent but nonsignificant decrease (-21%) in phosphorylation of a 52 kDa band occurred in chicks with passive avoidance training compared with water-trained and untrained chicks.(ABSTRACT TRUNCATED AT 250 WORDS)