Phospho-Ser784-VCP Is Required for DNA Damage Response and Is Associated with Poor Prognosis of Chemotherapy-Treated Breast Cancer

Abstract

Highlights d DNA damage-induced p-Ser 784 -VCP enhances chromatinassociated protein degradation d p-Ser 784 -VCP has reduced interaction with NPL4/UFD1 and polyubiquitinated substrates d VCP phosphorylation on Ser 784 is important for DNA damage response and cell survival d p-Ser 784 -VCP correlates with poor survival of chemotherapytreated cancer patients

Ser 784 phosphorylation: a clinically relevant enhancer of VCP function in the DNA damage response

“…In comparison, the rescuing abilities of these two VCP mutants with regard to the buildup of nucleoplasmic K48-polyubiquitin do not differ significantly. 7 These findings are consistent with the well-known importance of VCP for chromatin-associated degradation during DDR and suggest that Ser 784 phosphorylation may be a selective functional accelerator in this regard ( Figure 1b ). However, the potential effects of Ser 784 phosphorylation on soluble nuclear proteins cannot be ruled out.…”

“…However, this theory remained untested for 15 years until our recent study. 7 Similar to Livingstone et al 4 we serendipitously detected pSer 784 -VCP in human breast cancer samples using a crossreacting phospho-PFN1 antibody. Motivated by the chemotherapy-dependent correlation with patient survival, we identified the unknown nuclear antigen of the phospho-PFN1 antibody to be pSer 784 -VCP.…”

“…Another interesting finding in our study is that Ser 784 phosphorylation, within the C-terminal tail of VCP, decreases its interaction with N-domain-binding cofactors NPL4/UFD1 and K48-polyubiquitins, 7 indicative of long-range inter-domain conformational change. Notably, an early report by Klein et al identified several AKT (AK strain Transforming, also known as protein kinase B) phosphorylation sites in VCP (Ser 352 , Ser 746 , and Ser 748 ), and reported that an increase in cellular AKT activity decreases VCP/polyubiquitin interaction.…”

“…Thus, our data for the first time uncover the functional significance and clinical relevance of Ser 784 phosphorylation of VCP. 7 On a mechanistic level, our study suggests that the functional importance of Ser 784 phosphorylation for DDR is due, at least partially, to the increased VCP activity in chromatin-associated degradation. We found that VCP knockdown causes significant K48-polyubiquitin buildup on chromatin which can be fully rescued by the phospho-mimetic (S784D, serine 784 to aspartate) but not phospho-resistant (S784A, serine 784 to alanine) VCP mutants.…”

“…Thus, our data for the first time uncover the functional significance and clinical relevance of Ser 784 phosphorylation of VCP. 7 …”