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Quantitative Analysis of Alternative Pre-mRNA Splicing in Mouse Brain Sections Using RNA In Situ Hybridization Assay
Published on: August 26, 2018
Subcellular localization and function of alternatively spliced Noxo1 isoforms
Takehiko Ueyama1, Kristen Lekstrom, Satoshi Tsujibe
1Molecular Defenses Section, Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA. tueyama@kobe-u.ac.jp
Free Radical Biology & Medicine
|December 27, 2006
Summary
The four Nox organizer 1 (Noxo1) isoforms, generated by alternative splicing, exhibit distinct subcellular localizations due to their unique PX domains. These localizations critically influence their ability to support Nox1 enzyme activity.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Nox organizer 1 (Noxo1) is a p47(phox) homolog involved in regulating NADPH oxidase (Nox) enzyme activity.
- Noxo1 is produced in four isoforms (alpha, beta, gamma, delta) through alternative mRNA splicing, resulting in unique N-terminal PX domains.
Purpose of the Study:
- To investigate the subcellular distribution of Noxo1 isoforms and their isolated PX domains.
- To determine how Noxo1 isoform localization affects Nox1 enzyme activity.
- To elucidate the role of variant PX domains in Noxo1 function and localization.
Main Methods:
- Transfection of HEK293 and COS-7 cells with GFP-fusion proteins of Noxo1 isoforms and their PX domains.
- Analysis of subcellular localization using fluorescence microscopy.
- Measurement of Nox1 activity in transfected cells.
- Phospholipid binding assays for PX domains.
Main Results:
- Noxo1 isoforms display differential subcellular localization (plasma membrane, nucleus, intracellular vesicles) dictated by their PX domains.
- Noxo1beta and Noxo1gamma show plasma membrane localization and support higher Nox1 activity in HEK293 cells.
- Noxo1 isoform localization and subsequent Nox1 activity can vary between cell types (e.g., HEK293 vs. COS-7).
- PX domains of Noxo1beta and Noxo1gamma bind similar phospholipids, including phosphatidic acid.
Conclusions:
- Variant PX domains are key determinants of Noxo1 isoform subcellular localization.
- Noxo1 localization directly impacts its ability to modulate Nox1 enzyme activity.
- Noxo1 isoforms do not alter p22(phox) localization, but Nox1 is required for p22(phox) transport to the plasma membrane.
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