Identification of new interacting partners of the shuttling protein ubinuclein (Ubn-1)

Interaction of Ubinuclein-1, a nuclear and adhesion junction protein, with the 14-3-3 epsilon protein in epithelial cells: Implication of the PKA pathway

“…A consensus binding motif for the 14-3-3 family of proteins is present in the Ubn-1 sequence (RXXXSXP type 2 motif; amino acids 348-354) (Muslin et al, 1996). As common partners of the isoform of 14-3-3 were identified among the binding partners of Ubn-1 (Lupo et al, 2012), we investigated whether both proteins could interact in a Fig. 1.…”

“…Comparison of sorted proteins obtained by proteomic approaches used to identify Ubn-1 (Lupo et al, 2012) or 14-3-3 associated proteins (Liang et al, 2009;Zuo et al, 2010) revealed common partners, such as, beta-actin, tropomysosin 3, thioredoxin, tubulin beta-2C chain, hnRNP C and heat shock proteins (90 kDa and 70 kDa). However, we did not identify 14-3-3 as an Ubn-1 partner in our previous work, since the proteomic approach had been carried out with a GST-Ubn-1 recombinant protein produced in bacteria and thus not phosphorylated.…”

“…The other proteins of the TJ plaque are represented by non-PDZ proteins such as cingulin and paracingulin/JACOP protein, angiomotin family proteins, signaling and regulators of small GTPase proteins, and symplekin (Guillemot et al, 2008). Using mass spectrometry, we previously identified LYRIC and spectrin as partners of Ubinuclein (Ubn-1), together with actin (Lupo et al, 2012). It is noteworthy that the former proteins have been shown to belong to the non-PDZ proteins of the TJ plaque (Britt et al, 2004;Mattagajasingh et al, 2000).…”

“…At TJs, several NACos have been described, such as ZO1, ZO2, symplekin, and huASH1, which contribute to the localization of transcription factors (ZONAB/DbpA and AP-1), to mRNA processing, and to chromatin remodeling respectively (Matter and Balda, 2007). We previously reported that Ubn-1 shuttles between the nucleus and the TJs, thus belonging to the NACos (Aho et al, 2009;Lupo et al, 2012). When Ubn-1 is localized in the nucleus, it interacts with cellular transcription factors of the leucine-zipper family such as AP1, C/EBP or the viral transcription factor EB1 of EBV (also called ZEBRA or Zta; Aho et al, 2000;Gruffat et al, 2011).…”

“…Ubn-1 can also play a role as a histone chaperone protein (Balaji et al, 2009;Banumathy et al, 2009;Tang et al, 2012). We have shown that when Ubn-1 is localized at TJs, it interacts with ZO1 and cingulin (Aho et al, 2009;Lupo et al, 2012). However, the role of Ubn-1 as a nuclear and junctional shuttle protein in epithelial cells remains elusive.…”