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Tyrosine phosphorylation in a model of ischemia using the rat hippocampal slice: specific, long-term decrease in the
Journal of Neurochemistry
|October 1, 1995
Summary
Brief ischemia significantly impacts hippocampal protein tyrosine phosphorylation, particularly PSD-GP180. Calcium levels critically influence the recovery of phosphotyrosine-PSD-GP180 after ischemic events.
Area of Science:
- Neuroscience
- Molecular Biology
- Biochemistry
Background:
- Tyrosine phosphorylation regulates critical cellular functions.
- Hippocampal proteins, including glycoproteins, are targets of tyrosine phosphorylation.
- Postsynaptic density (PSD)-associated glycoprotein PSD-GP180 is a key component of synaptic structures.
Purpose of the Study:
- To investigate the effects of ischemic-like conditions on protein and glycoprotein tyrosine phosphorylation in hippocampal slices.
- To determine the impact of brief ischemia on specific tyrosine-phosphorylated proteins, including GP110 and PSD-GP180.
- To explore the role of calcium in the recovery of tyrosine phosphorylation after ischemia.
Main Methods:
- Incubation of hippocampal slices in oxygenated Krebs-Ringer buffer (KRB) with glucose.
- Induction of in vitro ischemia by transferring slices to N2-equilibrated, glucose-free KRB.
- Analysis of tyrosine phosphorylation levels of proteins and glycoproteins using Western blotting or similar techniques.
- Assessment of calcium dependency on phosphotyrosine recovery.
Main Results:
- Hippocampal slices exhibited baseline tyrosine phosphorylation of proteins and glycoproteins, including GP110 and PSD-GP180.
- Ischemic-like conditions led to the rapid loss of detectable tyrosine-phosphorylated GP110 and PSD-GP180.
- GP110 was rapidly rephosphorylated upon reoxygenation and glucose availability.
- Short ischemic periods caused long-term loss of phosphotyrosine-PSD-GP180, which was calcium-dependent for recovery.
Conclusions:
- Brief ischemia profoundly disrupts tyrosine phosphorylation of specific hippocampal proteins, notably PSD-GP180.
- The loss of phosphotyrosine-PSD-GP180 is a persistent effect of ischemia and is modulated by extracellular calcium.
- These findings highlight the vulnerability of synaptic protein phosphorylation to ischemic insults and suggest calcium-dependent mechanisms in recovery.