Wang, Chenji

Interplay between cell polarity module Scribble‐Lethal Giant Larvae‐Discs Large 1 (DLG1) and Yes‐associated protein (YAP) appears critical in tumor metastasis. We identified zinc finger protein 191 (ZNF191) as a metastasis suppressor acting through DLG‐YAP crosstalk in hepatocellular carcinoma (HCC). Overexpression of ZNF191 in HCC cells impaired cell motility, while ZNF191 depletion promoted cell migration in vitro and metastasis in vivo through triggering YAP signaling. Chromatin immunoprecipitation‐sequencing revealed that ZNF191 specifically bound to the promoter of DLG1, a cell polarity maintainer and a negative regulator of YAP. The binding sequence of ZNF191 at the DLG1 promoter is a seven‐repeat of TCAT motif. Double‐knockdown experiments inferred that DLG1 was not only the mediator of the function of ZNF191 to suppress migration but also a link between ZNF191 and YAP signaling. Decreased expression of ZNF191 in human metastatic HCC specimens correlated positively with DLG1 levels but inversely with YAP activation. Our findings illustrate a YAP‐targeting, antimetastasis function of ZNF191, thereby representing a possible prognostic marker and a potential target for metastasis therapy. Conclusion: ZNF191 directly binds to the DLG1 promoter at a typical TCAT repeating motif and activates the expression of DLG1; through up‐regulating DLG1, ZNF191 inhibits cell migration and YAP activation in HCC cells and eventually inhibits metastasis. (Hepatology 2016;64:1148‐1162)

ASPP2 is an important tumor suppressor protein promoting p53‐dependent and‐independent apoptosis. However, it has been unclear how ASPP2 protein is regulated. Here, we identified Itch as the E3 ubiquitin ligase for ASPP2. Itch interacts with ASPP2 and mediates its degradation and ubiquitination in vivo. The PPXY motif of ASPP2 interacts with the WW domains of Itch. Yap1 competes with Itch for binding to ASPP2, and prevents Itch‐mediated degradation and ubiquitination of ASPP2. Together, these observations reveal that Itch and Yap1 have antagonistic roles in the regulation of ASPP2 protein stability through competing post‐translational regulatory mechanism of ASPP2.