Acetylation of RTN-1C regulates the induction of ER stress by the inhibition of HDAC activity in neuroectodermal tumors

Reticulons are a family of highly conserved proteins, localized in the endoplasmic reticulum (ER) and involved in different cellular functions, such as intracellular membrane trafficking, apoptosis and nuclear envelope formation. The reticulon protein family consists of four members, but their specific functions are presently poorly understood. RTN-1C overexpression triggers apoptosis, regulating ER stress versus DNA damage-induced cell death in a mutually exclusive way. The different RTN isoforms share a C-terminal reticulon homology domain containing two hydrophobic segments and a 66-amino acid hydrophilic loop. In the C-terminal region of RTN-1C, a unique consensus sequence (GAKRH) has recently been identified, showing 100% identity with the DNA-binding domain of histone H4. In this study, we show that this sequence is essential for RTN-1C-mediated apoptosis. It is noteworthy that the lysine 204 present in this region is post-translationally modified by acetylation and that this event is associated with a significant decrease in histone deacetylase activity and contributes to RTN-1C binding to DNA. These data demonstrate a molecular mechanism by which RTN-1C controls apoptosis and indicate this protein to be a novel potential target for cancer therapy. Oncogene (2009) 28, 3814-3824; doi:10.1038/onc.2009.233; published online 10 August 2009