LAUSR

Dear editor, ADP-ribosylation is a post-translational modification catalysed by poly(ADP-ribose) polymerases (PARPs) and plays important roles in diverse biological processes, such as DNA repair, chromatin remodelling, telomere homeostasis, transcription, chromosome segregation, cell proliferation, and cell death [1, 2]. While much is known about the cellular roles of PARPs that catalyse polyADP ribosylation, the function of the PARPs that catalyse monoADP ribosylation is substantially less understood. PARP10 is a mono-ADP-ribosyltransferase and has been found to be involved in diverse biological processes, such as nuclear factor-κB (NF-κB) signalling and tumor development [3, 4].More recently,we identified PARP10 as a tumor metastasis suppressor [5]. We demonstrated that PARP10 interacted with and mono-ADP-ribosylates Aurora A, and then inhibited its kinase activity, thereby regulating Aurora A downstream signalling to suppress tumor cell epithelial-mesenchymal transition processes and tumor metastasis. Moreover, the expression level of PARP10 was lower in intrahepatic metastatic hepatocellular carcinoma (HCC) than in corresponding primary HCC and adjacent non-tumor tissues [5]. Although PARP10 plays important roles in physiological and pathological processes, the regulation and modification mechanisms of PARP10 remain largely unclear. In addition to Aurora A, RING finger 114 (RNF114), a ubiquitin E3 ligase [6], was also found in the PARP10 complex [5], suggesting that RNF114 might also be a PARP10interacting protein. Then, we performed exogenous and endogenous reciprocal immunoprecipitation assays to verify the interaction between PARP10 and RNF114. As expected, exogenously expressed HA-RNF114 interacted with S-Flag-SBP (SFB)-PARP10, and vice versa (Supplementary Figure S1). Endogenous PARP10 also interacted with RNF114, as determined by a co-immunoprecipitation