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Updated: Jun 8, 2026

Preparation of Quality Inositol Pyrophosphates
Published on: September 3, 2011
Inositol hexakisphosphate kinases promote autophagy
Eiichiro Nagata1, Adolfo Saiardi, Hideo Tsukamoto
1Department of Neurology, Tokai University School of Medicine, 143 Shimo-Kasuya, Isehara, Kanagawa 259-1193, Japan.
Inositol hexakisphosphate kinases (InsP(6)Ks) promote autophagy and increase cell death. This study reveals InsP(6)Ks induce caspase-independent cell death, opening new autophagy pathways.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Cellular diphosphoinositol pentakisphosphate (InsP(7)) levels are linked to increased cell death sensitivity.
- Inositol hexakisphosphate kinases (InsP(6)Ks) are enzymes responsible for synthesizing InsP(7).
Purpose of the Study:
- To investigate the relationship between InsP(6)Ks and autophagy.
- To understand the role of InsP(6)Ks in cell death pathways.
Main Methods:
- Overexpression and RNAi systems for InsP(6)Ks.
- Immunoblotting, immunocytochemistry, and immuno-electron microscopy for LC3 conversion (LC3-I to LC3-II).
- Propidium iodide staining for cell death assessment.
- Treatment with staurosporine and z-VAD-fmk (pan-caspase inhibitor).
- Analysis of mammalian target of rapamycin (mTOR) phosphorylation.
Main Results:
- InsP(6)Ks overexpression significantly increased autophagosome formation and cell death.
- RNAi-mediated reduction of InsP(6)Ks suppressed autophagosome formation.
- Stress conditions (staurosporine) further enhanced InsP(6)Ks-induced autophagy and cell death.
- InsP(6)Ks-induced cell death was partially resistant to caspase inhibition.
- mTOR phosphorylation was decreased in cells overexpressing InsP(6)Ks.
Conclusions:
- InsP(6)Ks play a crucial role in promoting autophagy.
- InsP(6)Ks induce a caspase-independent cell death pathway.
- The mTOR pathway is implicated in regulating InsP(6)Ks-driven autophagy.
- This study identifies a novel autophagy pathway mediated by InsP(6)Ks.
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08:07Identification of Inositol Phosphate or Phosphoinositide Interacting Proteins by Affinity Chromatography Coupled to Western Blot or Mass Spectrometry
Published on: July 26, 2019
09:22Absolute Quantitation of Inositol Pyrophosphates by Capillary Electrophoresis Electrospray Ionization Mass Spectrometry
Published on: August 13, 2021
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