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First published online 12 May 2009
doi: 10.1242/jcs.042226
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Research Article |
1 Laboratory of Genetics, Department of Microbiology and Immunology and Institute for Medical Sciences, Chonbuk National University Medical School, Chonju 561-712, South Korea
2 The Geriatric Research Education and Clinical Center, Veteran's Affairs Medical Center, Bedford, MA 01730, USA
3 Department of Neurology, Boston University School of Medicine, Boston, MA 02118, USA
4 Research Division, Jinis Biopharmaceuticals, Chonju 561-360, South Korea
5 Signal Transduction Laboratory, Cancer Research UK London Research Institute, London WC2A 3PX, UK
* Author for correspondence (e-mail: seonghong{at}chonbuk.ac.kr)
Accepted 23 February 2009
The cellular generation of toxic metabolites and subsequent detoxification failure can cause the uncontrolled accumulation of these metabolites in cells, leading to cellular dysfunction. Amyloid-β protein (Aβ), a normal metabolite of neurons, tends to form toxic oligomeric structures that cause neurodegeneration. It is unclear how healthy neurons control the levels of intracellular oligomeric Aβ in order to avoid neurodegeneration. Using immunochemical and biochemical studies, we show that the Aβ-binding serine protease Omi is a stress-relieving heat-shock protein that protects neurons against neurotoxic oligomeric Aβ. Through its PDZ domain, Omi binds preferentially to neurotoxic oligomeric forms of Aβ rather than non-toxic monomeric forms to detoxify oligomeric Aβ by disaggregation. This specific interaction leads not only to mutual detoxification of the pro-apoptotic activity of Omi and Aβ-induced neurotoxicity, but also to a reduction of neurotoxic-Aβ accumulation. The neuroprotective role of Omi is further supported by its upregulation during normal neurogenesis and neuronal maturation in mice, which could be in response to the increase in the generation of oligomeric Aβ during these processes. These findings provide novel and important insights into the detoxification pathway of intraneuronal oligomeric Aβ in mammals and the protective roles of Omi in neurodegeneration, suggesting a novel therapeutic target in neurodegenerative diseases.
Key words: HtrA2 (Omi), Heat-shock protein, Oligomeric amyloid-β protein, Protein interaction, Mutual detoxification, Disaggregation
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