Histone deacetylase-related protein inhibits AES-mediated neuronal cell death by direct interaction.
Histone deacetylase-related protein (HDRP), an alternatively spliced and truncated form of histone deacetylase-9 that lacks a C-terminal catalytic domain, protects neurons from death. In an effort to understand the mechanism by which HDRP mediates its neuroprotective effect, we screened for proteins in the brain that interact with HDRP by using a yeast two-hybrid assay. One of the HDRP-interacting proteins identified in this screen was amino enhancer of split (AES), a 197-amino acid protein belonging to the Groucho family. Interaction between HDRP and AES was verified by in vitro binding assays, coimmunoprecipitation, and colocalization studies. To investigate the significance of the HDRP-AES association to the regulation of neuronal survival, we used cultured cerebellar granule neurons, which undergo apoptosis when treated with low potassium (LK) medium. We found that in contrast to HDRP, whose expression is markedly reduced by LK treatment, AES expression was not appreciably altered. Forced expression of AES in healthy neurons results in cell death, an action that is blocked by the coexpression of HDRP. AES is a truncated version of larger Groucho-related proteins, one of which is transducin-like enhancer of split (TLE)-1. We found that the expression of TLE1 is reduced in LK-treated neurons and the forced expression of TLE1 blocks LK-induced neuronal death as well as death induced by AES. Our results show that AES has apoptotic activity in neurons and suggest that neuroprotection by HDRP is mediated by the inhibition of this activity through direct interaction.
Zhang
Xiaoguang
X
Department of Molecular and Cell Biology, University of Texas at Dallas, Richardson, Texas 75080, USA.
Chen
Hsin-Mei
HM
Jaramillo
Eduardo
E
Wang
Lulu
L
D'Mello
Santosh R
SR
D017209:Apoptosis / Q000502:physiology*; D015153:Blotting, Western; D002460:Cell Line; D056970:Co-Repressor Proteins; D006655:Histone Deacetylases / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D009474:Neurons / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D020798:Two-Hybrid System Techniques
D056970:Co-Repressor Proteins; D012097:Repressor Proteins; C499043:TLE1 protein, human; C498445:TLE5 protein, human; C486544:HDAC9 protein, human; D006655:Histone Deacetylases