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Using Live Cell STED Imaging to Visualize Mitochondrial Inner Membrane Ultrastructure in Neuronal Cell Models
Published on: June 30, 2023
Expression of polyalanine stretches induces mitochondrial dysfunction.
Kazuya Toriumi1, Yoko Oma, Yoshihiro Kino
1Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan.
Journal of Neuroscience Research
|January 25, 2008
Summary
Polyalanine diseases involve toxic protein stretches that aggregate in cells. This study reveals these stretches damage mitochondria, suggesting a new mechanism for cell death in these genetic disorders.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- Polyalanine diseases are a class of genetic disorders characterized by expanded triplet repeats in specific genes.
- These expansions lead to aberrantly elongated polyalanine stretches in translated proteins.
Purpose of the Study:
- To investigate the cellular localization, aggregation, and toxicity of elongated polyalanine stretches.
- To identify proteins that bind to polyalanine stretches and may mediate cytotoxicity.
- To elucidate the mechanism by which polyalanine stretches induce cell death.
Main Methods:
- Expression of yellow fluorescent protein (YFP)-fused polyalanine stretches in cells.
- Localization and aggregation studies using microscopy.
- Protein-binding assays to identify interacting partners.
- Mitochondrial function assays, including assessment of succinate dehydrogenase activity and mitochondrial membrane potential.
Main Results:
- Elongated polyalanine stretches localized to the cytoplasm and formed aggregates.
- Polyalanine stretches were found to be toxic and directly associated with mitochondria.
- Several mitochondrial proteins were identified as binding partners, including succinate dehydrogenase subunit A.
- Expression of polyalanine stretches led to decreased succinate dehydrogenase activity and reduced mitochondrial membrane potential.
Conclusions:
- Polyalanine stretches induce cytotoxicity through direct association with and dysfunction of mitochondria.
- Mitochondrial dysfunction, including impaired oxidative activity and reduced membrane potential, is a key mechanism in polyalanine disease pathogenesis.
- This mitochondrial-based mechanism may be common to all polyalanine diseases.
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Lesson: Translation
Translation is the process of synthesizing proteins from the genetic information carried by messenger RNA (mRNA). Following transcription, it constitutes the final step in the expression of genes. This process is carried out by ribosomes, complexes of protein and specialized RNA molecules. Ribosomes, transfer RNA (tRNA), and other proteins produce a chain of amino acids—the polypeptide—as the end product of translation.
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