A Potential Role Of Protein Palmitoylation And ZDHHC16 In DNA Damage Response

Protein palmitoylation,or protein S-acylation,is a post-translational modification of adding a palmitate moiety to specific Cys residues by a family of proteins named protein acyltransferases.A number of cellular proteins have been reported to be palmitoylated,which are involved in different cellular activities such as cell signaling,protein trafficking,and cell adhesion.Recent studies have implicated protein palmitoylation and PATs in cancer development.The expression of some zDHHC genes are altered in various cancer samples.Yet how PATs participate in cancer development remains unclear.Cancer development is driven by accumulation of gene mutations,especially loss-of-function mutations of tumor suppressors and gain-of-function mutations of oncoproteins.Yet the cell has a defense system,the DNA damage response,to monitor DNA damage and to repair the damage or eliminate the cells with irreparable DNA lesions.Thus,a functional DNA damage response is critical for maintaining genome integrity and preventing tumor development.Up to date,it is not known whether protein palmitoylation plays a role in DNA damage response.In the present study,we investigated the roles of protein palmitoylation in DNA damage response,the major tumor suppression pathway.We applied the 2-bromopalmitate,a widely used protein acyltransferases inhibitor,to inhibit protein acyltransferases in primary mouse embryonic fibroblasts.Main techniques used in the research include:1)Western Blot analysis;2)Flow cytometry;3)In Vitro analysis of DNA damage foci positive for γH2AX,TopBP1,and BRCA1;4)RT-PCR.We found that 2-bromopalmitate impeded several aspects of DNA damage response including ATM activation,p53 induction and activation,cell cycle arrest at G2/M phase,and assembly/disassembly of DNA damage foci,most of which were also observed in MEFs deficient of zDHHC16 gene,a palmitoyltransferase.These findings,for the first time,unravel an important function of PATs,in particular zDHHC16,in DNA damage response and in ATM activation,and provide a possible explanation on how some zDHHC proteins participate in tumorigenesis.