RNF146 is a poly(ADP-ribose)-directed E3 ligase that regulates axin degradation and Wnt signalling

Abstract

The Wnt/β-catenin signalling pathway plays essential roles in embryonic development and adult tissue homeostasis, and deregulation of this pathway has been linked to cancer. Axin is a concentration-limiting component of the β-catenin destruction complex, and its stability is regulated by tankyrase. However, the molecular mechanism by which tankyrase-dependent poly(ADP-ribosyl)ation (PARsylation) is coupled to ubiquitylation and degradation of axin remains undefined. Here, we identify RNF146, a RING-domain E3 ubiquitin ligase, as a positive regulator of Wnt signalling. RNF146 promotes Wnt signalling by mediating tankyrase-dependent degradation of axin. Mechanistically, RNF146 directly interacts with poly(ADP-ribose) through its WWE domain, and promotes degradation of PARsylated proteins. Using proteomics approaches, we have identified BLZF1 and CASC3 as further substrates targeted by tankyrase and RNF146 for degradation. Thus, identification of RNF146 as a PARsylation-directed E3 ligase establishes a molecular paradigm that links tankyrase-dependent PARsylation to ubiquitylation. RNF146-dependent protein degradation may emerge as a major mechanism by which tankyrase exerts its function.

Regulation of NF-κB signalling by the mono-ADP-ribosyltransferase ARTD10

“…Recent studies have demonstrated that ARTD5-and 6-(formerly Tankyrase1 and 2) dependent PARylation of axin results in the recruitment of the ubiquitin E3 ligase RNF146 and subsequent pUb-dependent proteasomal degradation of axin, a negative regulator of WNT signalling 9,10,25 . Similarly, 3BP2 is substrate of ARTD5 and RNF146.…”

“…PARylation regulates various cellular processes, such as DNA repair, specific signalling processes and gene transcription 5 . The functional consequences of PARylation are mediated by distinct protein domains, including macrodomains, WWE (named after two conserved tryptophan residues and a glutamate residue) and PAR-binding zinc-finger (PBZ) domains [6][7][8][9][10] . In contrast to the function of class 1 ARTD enzyme-mediated PARylation, little is known about the biological relevance of mono-ADP-ribosyltransferases.…”

HectD1 E3 Ligase Modifies Adenomatous Polyposis Coli (APC) with Polyubiquitin to Promote the APC-Axin Interaction

“…The stabilities of Axin and Dishevelled, an upstream positive component of the pathway, are regulated by the E3 ligase activities of RNF146 and KLHL12, respectively. The KLHL12-mediated proteasomal degradation of Dishevelled is a Wnt-regulated event, but it is unclear whether the same is true of RNF146-mediated Axin degradation (15)(16)(17). Like KLHL12, the recently described ZNRF3 represents another E3 ubiquitin ligase that negatively regulates proximal events in the Wnt pathway.…”

Reversible Modification of Adenomatous Polyposis Coli (APC) with K63-linked Polyubiquitin Regulates the Assembly and Activity of the β-Catenin Destruction Complex

“…1D). We suspect that the high-molecular-weight smears of co-precipitated endogenous and Myc-Axin (AXIN1 * ), could represent PARsylated/K48-polyubiquitylated populations that have accumulated in MG132-treated cells (28,30). The total precipitated APC pool also resolved with a retarded electrophoretic mobility (APC * ), as revealed by immunoblotting with a rabbit polyclonal APC antibody (clone H-290), but the reason for this is unclear (Fig.…”

“…K48-linked adducts controls not only the stability of ␤-catenin, but also that of several Wnt pathway components including Axin, Dvl, and APC (27)(28)(29)(30). Interestingly, Dvl and APC are also modified with K63-linked ubiquitin chains, as inferred from loss-of-function studies of the deubiquitylating enzymes CYLD and Trabid, respectively (31,32).…”