The Journal of Neuroscience, March 4, 2009, 29(9):2824-2832; doi:10.1523/JNEUROSCI.6186-08.2009
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Cellular/Molecular
Histone Deacetylase Inhibitors Prevent p53-Dependent and p53-Independent Bax-Mediated Neuronal Apoptosis through Two Distinct Mechanisms
Takuma Uo,1
Timothy D. Veenstra,2 and
Richard S. Morrison1
1Department of Neurological Surgery, University of Washington School of Medicine, Seattle, Washington 98195-6470, and 2Laboratory of Proteomics and Analytical Technologies, Science Applications International Corporation-Frederick, Inc., National Cancer Institute at Frederick, Frederick, Maryland 21702-1201
Correspondence should be addressed to Dr. Richard S. Morrison, Department of Neurological Surgery, University of Washington School of Medicine, Box 356470, Seattle, WA 98195-6470. Email: yael{at}u.washington.edu
Pharmacological manipulation of protein acetylation levels by histone deacetylase (HDAC) inhibitors represents a novel therapeutic strategy to treat neurodegeneration as well as cancer. However, the molecular mechanisms that determine how HDAC inhibition exerts a protective effect in neurons as opposed to a cytotoxic action in tumor cells has not been elucidated. We addressed this issue in cultured postnatal mouse cortical neurons whose p53-dependent and p53-independent intrinsic apoptotic programs require the proapoptotic multidomain protein, Bax. Despite promoting nuclear p53 accumulation, Class I/II HDAC inhibitors (HDACIs) protected neurons from p53-dependent cell death induced by camptothecin, etoposide, heterologous p53 expression or the MDM2 inhibitor, nutlin-3a. HDACIs suppressed p53-dependent PUMA expression, a critical signaling intermediate linking p53 to Bax activation, thus preventing postmitochondrial events including cleavage of caspase-9 and caspase-3. In human SH-SY5Y neuroblastoma cells, however, HDACIs were not able to prevent p53-dependent cell death. Moreover, HDACIs also prevented caspase-3 cleavage in postnatal cortical neurons treated with staurosporine, 3-nitropropionic acid and a Bcl-2 inhibitor, all of which require the presence of Bax but not p53 to promote apoptosis. Although these three toxic agents displayed a requirement for Bax, they did not promote PUMA induction. These results demonstrate that HDACIs block Bax-dependent cell death by two distinct mechanisms to prevent neuronal apoptosis, thus identifying for the first time a defined molecular target for their neuroprotective actions.
Received Dec. 30, 2008;
revised Jan. 29, 2009;
accepted Jan. 30, 2009.
Correspondence should be addressed to Dr. Richard S. Morrison, Department of Neurological Surgery, University of Washington School of Medicine, Box 356470, Seattle, WA 98195-6470. Email: yael{at}u.washington.edu
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