Daxx (Phospho-Ser668) Antibody

Description: Acts as an adapter protein in a MDM2-DAXX-USP7 complex by regulating the RING-finger E3 ligase MDM2 ubiquitination activity. Under non-stress condition, in association with the deubiquitinating USP7, prevents MDM2 self-ubiquitination and enhances the intrinsic E3 ligase activity of MDM2 towards TP53, thereby promoting TP53 ubiquitination and subsequent proteasomal degradation. Upon DNA damage, its association with MDM2 and USP7 is disrupted.
Function: Transcription corepressor known to repress transcriptional potential of several sumoylated transcription factors. Down-regulates basal and activated transcription. Its transcription repressor activity is modulated by recruiting it to subnuclear compartments like the nucleolus or PML/POD/ND10 nuclear bodies through interactions with MCSR1 and PML, respectively. Seems to regulate transcription in PML/POD/ND10 nuclear bodies together with PML and may influence TNFRSF6-dependent apoptosis thereby. Inhibits transcriptional activation of PAX3 and ETS1 through direct protein-protein interactions. Modulates PAX5 activity; the function seems to involve CREBBP. Acts as an adapter protein in a MDM2-DAXX-USP7 complex by regulating the RING-finger E3 ligase MDM2 ubiquitination activity. Under non-stress condition, in association with the deubiquitinating USP7, prevents MDM2 self-ubiquitination and enhances the intrinsic E3 ligase activity of MDM2 towards TP53, thereby promoting TP53 ubiquitination and subsequent proteasomal degradation. Upon DNA damage, its association with MDM2 and USP7 is disrupted, resulting in increased MDM2 autoubiquitination and consequently, MDM2 degradation, which leads to TP53 stabilization. Acts as histone chaperone that facilitates deposition of histone H3.3. Acts as targeting component of the chromatin remodeling complex ATRX:DAXX which has ATP-dependent DNA translocase activity and catalyzes the replication-independent deposition of histone H3.3 in pericentric DNA repeats outside S-phase and telomeres, and the in vitro remodeling of H3.3-containing nucleosomes. Does not affect the ATPase activity of ATRX but alleviates its transcription repression activity. Upon neuronal activation associates with regulatory elements of selected immediate early genes where it promotes deposition of histone H3.3 which may be linked to transcriptional induction of these genes. Required for the recruitment of histone H3.3:H4 dimers to PML-nuclear bodies (PML-NBs); the process is independent of ATRX and facilitated by ASF1A; PML-NBs are suggested to function as regulatory sites for the incorporation of newly synthesized histone H3.3 into chromatin. In case of overexpression of centromeric histone variant CENPA (as found in various tumors) is involved in its mislocalization to chromosomes; the ectopic localization involves a heterotypic tetramer containing CENPA, and histones H3.3 and H4 and decreases binding of CTCF to chromatin. Proposed to mediate activation of the JNK pathway and apoptosis via MAP3K5 in response to signaling from TNFRSF6 and TGFBR2. Interaction with HSPB1/HSP27 may prevent interaction with TNFRSF6 and MAP3K5 and block DAXX-mediated apoptosis. In contrast, in lymphoid cells JNC activation and TNFRSF6-mediated apoptosis may not involve DAXX. Shows restriction activity towards human cytomegalovirus (HCMV). Plays a role as a positive regulator of the heat shock transcription factor HSF1 activity during the stress protein response (PubMed:15016915).
Subunit Structure: Homomultimer. Interacts (via C-terminus) with TNFRSF6 (via death domain). Interacts with PAX5, SLC2A4/GLUT4, MAP3K5, TGFBR2, phosphorylated dimeric HSPB1/HSP27, CENPC, ETS1, sumoylated PML, UBE2I, MCRS1 and TP53. Interacts (via N-terminus) with HIPK2 and HIPK3. Interacts with HIPK1, which induces translocation from PML/POD/ND10 nuclear bodies to chromatin and enhances association with HDAC1. Interacts (non-phosphorylated) with PAX3, PAX7, DEK, HDAC1, HDAC2, HDAC3, acetylated histone H4 and histones H2A, H2B, H3, H3.3 and H4. Interacts with SPOP; mediating CUL3-dependent proteosomal degradation. Interacts with CBP; the interaction is dependent the sumoylation of CBP and suppresses CBP transcriptional activity via recruitment of HDAC2 directly in the complex with TP53 and HIPK2. Interacts with AXIN1; the interaction stimulates the interaction of DAXX with TP53, stimulates 'Ser-46' phosphorylation of TP53 on and induces cell death on UV irradiation. Interacts with MDM2; the interaction is direct. Interacts with USP7; the interaction is direct and independent of MDM2 and TP53. Part of a complex with DAXX, MDM2 and USP7 under non-stress conditions. Interacts (via N-terminus) with RASSF1 (via C-terminus); the interaction is independent of MDM2 and TP53; RASSF1 isoform A disrupts interactions among MDM2, DAXX and USP7, thus contributing to the efficient activation of TP53 by promoting MDM2 self-ubiquitination in cell-cycle checkpoint control in response to DNA damage. Interacts with ATRX to form the chromatin remodeling complex ATRX:DAXX. Interacts with human cytomegalovirus/HHV-5 tegument phosphoprotein pp71 and protein UL123. Interacts with Epstein-Barr virus protein BNRF1. Interacts with human adenovirus 5 E1B-55K protein; this interaction might alterate the normal interactions of DAXX, PML, and TP53, which may contribute to cell transformation (PubMed:14557665). Interacts with HSF1 (via homotrimeric form preferentially); this interaction relieves homotrimeric HSF1 from repression of its transcriptional activity by HSP90-dependent multichaperone complex upon heat shock (PubMed:15016915).
Post-translational Modifications: Sumoylated with SUMO1 on multiple lysine residues. Phosphorylated by HIPK1 upon glucose deprivation. Polyubiquitinated; which is promoted by CUL3 and SPOP and results in proteasomal degradation. Ubiquitinated by MDM2; inducing its degradation. Deubiquitinated by USP7; leading to stabilize it.
Similarity: The Sumo interaction motif mediates Sumo binding, and is required both for sumoylation and binding to sumoylated targets. Belongs to the DAXX family.