Heat Shock Transcription Factor 1-activating Compounds Suppress Polyglutamine-induced Neurodegeneration through Induction of Multiple Molecular Chaperones

Nobuhiro Fujikake,Yoshitaka Nagai,H Akiko Popiel,Yuma Okamoto,Masamitsu Yamaguchi,Tatsushi Toda

doi:10.1074/jbc.m710521200

Nobuhiro Fujikake, Yoshitaka Nagai + Show 4 more

Open Access

https://doi.org/10.1074/jbc.m710521200

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Abstract

Many neurodegenerative diseases including Alzheimer, Parkinson, and polyglutamine (polyQ) diseases are thought to be caused by protein misfolding. The polyQ diseases, including Huntington disease and spinocerebellar ataxias (SCAs), are caused by abnormal expansions of the polyQ stretch in disease-causing proteins, which trigger misfolding of these proteins, resulting in their deposition as inclusion bodies in affected neurons. Although genetic expression of molecular chaperones has been shown to suppress polyQ protein misfolding and neurodegeneration, toward developing a therapy, it is ideal to induce endogenous molecular chaperones by chemical administration. In this study, we assessed the therapeutic effects of heat shock transcription factor 1 (HSF1)-activating compounds, which induce multiple molecular chaperones, on polyQ-induced neurodegeneration in vivo. We found that oral administration of 17-(allylamino)-17-demethoxygeldanamycin (17-AAG) markedly suppresses compound eye degeneration and inclusion body formation in a Drosophila model of SCA. 17-AAG also dramatically rescued the lethality of the SCA model (74.1% rescue) and suppressed neurodegeneration in a Huntington disease model (46.3% rescue), indicating that 17-AAG is widely effective against various polyQ diseases. 17-AAG induced Hsp70, Hsp40, and Hsp90 expression in a dose-dependent manner, and the expression levels correlated with its therapeutic effects. Furthermore, knockdown of HSF1 abolished the induction of molecular chaperones and the therapeutic effect of 17-AAG, indicating that its therapeutic effects depend on HSF1 activation. Our study indicates that induction of multiple molecular chaperones by 17-AAG treatment is a promising therapeutic approach for a wide range of polyQ diseases and possibly other neurodegenerative diseases.

Highlights

The accumulation and deposition of misfolded proteins in the brain has been recognized as a common molecular pathogenesis of various neurodegenerative diseases including Alzheimer disease, Parkinson disease, amyotrophic lateral sclerosis, and the polyglutamine4 diseases, and these diseases are called protein misfolding diseases [1]
We found that oral administration of 17-(allylamino)-17-demethoxygeldanamycin (17-AAG) markedly suppresses compound eye degeneration and inclusion body formation in a Drosophila model of SCA. 17-AAG dramatically rescued the lethality of the SCA model (74.1% rescue) and suppressed neurodegeneration in a Huntington disease model (46.3% rescue), indicating that 17-AAG is widely effective against various polyQ diseases. 17-AAG induced Hsp70, Hsp40, and Hsp90 expression in a dose-dependent manner, and the expression levels correlated with its therapeutic effects
Many neurodegenerative diseases including Alzheimer disease, Parkinson disease, amyotrophic lateral sclerosis, and the polyQ diseases are thought to be caused by protein misfolding, and suppression of protein misfolding by molecular chaperones is considered to be a common therapeutic approach for these neurodegenerative diseases [14]

Summary

EXPERIMENTAL PROCEDURES

Fly Stocks and Treatment—Flies were cultured and crossed under standard conditions at 25 °C. The data are expressed as the means Ϯ S.E. For immunohistochemical analysis, eye discs of the MJDtrQ78W flies treated with 17-AAG (1.5 ␮M) were dissected from crawling third instar larvae and fixed in 4% paraformaldehyde. The data are expressed as the means Ϯ S.E. Fly Survival Analyses—To examine the therapeutic effects of 17-AAG on the survival rate during development to adults of flies expressing the MJDtr-Q78 protein in the nervous system, we crossed flies homozygous for the UAS-MJDtr-Q78S transgene with flies bearing the elav-Gal driver transgene in trans to the balancer chromosome (CyO). RT-PCR Analyses—Total RNA was purified from whole bodies or eye-antennal discs of crawling third instar larvae of the MJDtr-Q78S flies and control flies expressing the GAL4 activator protein alone using the RNeasy Mini Kit (Qiagen) according to the manufacturer’s instructions and was reverse transcribed with random hexamer primers. 48 h after transfection, and the cell lysates were subjected to Western blot analyses

RESULTS

A Control

Findings

DISCUSSION