Co-translational protein aggregation after transient cerebral ischemia

Area of Science:

• Neuroscience
• Molecular Biology
• Biochemistry

Background:

• Transient cerebral ischemia causes irreversible translational inhibition, a key feature of delayed neuronal death.
• The precise mechanism behind this irreversible inhibition remains unclear.

Purpose of the Study:

• To investigate if abnormal aggregation of the translational complex causes irreversible translational inhibition after ischemia.
• To identify the components involved in this aggregation.

Main Methods:

• Utilized a rat transient cerebral ischemia model.
• Examined translational complex aggregation using electron microscopy and biochemical analyses.
• Assessed components such as ribosomal proteins, initiation factors, chaperones, and degradation enzymes.

Main Results:

• Cerebral ischemia (15-20 min) induced severe translational complex aggregation starting 30 min post-reperfusion and lasting until 48 h.
• Neurons destined to die showed clumped ribosomes forming abnormal aggregates, unlike controls.
• Key translational components, including ribosomal proteins, eukaryotic initiation factor-3eta, heat shock cognate protein 70, HSP40-Hdj1, and c-terminus of hsp70-interacting protein, were found in these aggregates and were ubiquitinated.

Conclusions:

• Ischemia damages co-translational chaperone and degradation machinery.
• This damage results in irreversible protein aggregation and destruction of the protein synthesis machinery, leading to neuronal death.