UBE2I (UBC9) interacts with TFAP2A, TFAP2B and TFAP2C, and the interaction site has been mapped to the C terminal region of TFAP2C; SUMOylation occurs on lysine-10 (Eloranta and Hurst 2002). As lysine-10 is conserved in TFAP2A and TFAP2B, SUMOylation of these factors is assumed to be on lysine-10 (Eloranta and Hurst 2002; Impens et al. 2014). SUMOylation causes a reduction in AP-2 transcriptional activation function but is required for its repressive function. A dominant negative mutant of UBC9 led to increased activation and reduced repressor function of TFAP2A and C, supporting the role of UBC9 in SUMOylation (Eloranta and Hurst 2002; Berlato et al. 2011). Isoform 1a of TFAP2A is SUMOylated, isoforms 1b and 1c lack lysine 10 and are not SUMOylated (Berlato et al. 2011). TFAP2D and TFAP2E lack lysine-10 and are thus assumed not to be SUMOylated. SUMOylation of TFAP2A blocked its ability to induce the expression of luminal genes and repression of basal genes (Bogachek et al. 2014). Disruption of the sumoylation pathway by knockdown of sumoylation enzymes, mutation of the SUMO-target lysine of TFAP2A, or treatment with sumoylation inhibitors induced MET in basal breast cancers, which was dependent on TFAP2A(Bogachek et al. 2014).
Eloranta, JJ, Hurst, HC
Li, T, Li, Y, Spanheimer, PM, Weigel, RJ, Park, JM, Kulak, MV, Bogachek, MV, Chen, Y, Cyr, AR, Woodfield, GW
Berlato, C, Hurst, HC, Scibetta, AG, Chan, KV, Price, AM, Canosa, M
Impens, F, Cossart, P, Radoshevich, L, Ribet, D
SUMO transferase activity of SUMO1:C93-UBE2I [cytoplasm]
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