XAV-939

1 . Chen HC, Zhu YT, Chen SY, Tseng SC.,Wnt signaling induces epithelial-mesenchymal transition with proliferation in ARPE-19 cells upon loss of contact inhibition.,Lab Invest. 2012 May;92(5):676-87.
Abstract
Proliferation and epithelial-mesenchymal transition (EMT) of the retinal pigment epithelium (RPE) are hallmarks of proliferative vitreoretinopathy. This study aims at clarifying the role of growth factors, such as epidermal growth factor (EGF), fibroblast growth factor-2 (FGF-2), and transforming growth factor-β1 (TGF-β1), in controlling how RPE proliferates while undergoing EMT. When contact inhibition of post-confluent ARPE-19 cells was disrupted by EGTA, an increase of BrdU labeling was noted only in the presence of EGF and/or FGF-2, and was accompanied by EMT as evidenced by the loss of a normal RPE phenotype (altered cytolocalization of RPE65, N-cadherin, ZO-1, and Na,K-ATPase) and the gain of a mesenchymal phenotype (increased expression of vimentin, S100A4, and α-smooth muscle actin). EMT with proliferation by EGTA+EGF+FGF-2 was accompanied by activation of canonical Wnt signaling (judged by the TCF/LEF promoter activity, increased nuclear levels of and interaction between β-catenin and LEF1 proteins, and the replication by overexpression of β-catenin), abolished by concomitant addition of XAV939, a Wnt inhibitor, but not associated with suppression of Hippo signaling (negative expression of nuclear TAZ or YAP and cytoplasmic p-TAZ or p-YAP). The causative role of Wnt signaling on EMT with proliferation was confirmed by overexpression of stable S33Y β-catenin with EGTA treatment. In addition, contact inhibition disrupted by EGTA in the presence of TGF-β1 also led to EMT, but suppressed proliferation and Wnt signaling. The Wnt signaling triggered by EGF+FGF-2 was sufficient and synergized with TGF-β1 in activating the Smad/ZEB1/2 signaling responsible for EMT. These findings establish a framework for further dissecting how RPE might partake in a number of proliferative vitreoretinopathies characterized by EMT.

2 . Ao A, Hao J, Hopkins CR, Hong CC.,DMH1, a Novel BMP Small Molecule Inhibitor, Increases Cardiomyocyte Progenitors and Promotes Cardiac Differentiation in Mouse Embryonic Stem Cells.,PLoS One. 2012;7(7):e41627. Epub 2012 Jul 27. bryonic Stem Cells. ,PLoS One. 2012;7(7):e41627. Epub 2012 Jul 27.
Abstract
The possibility of using cell-based therapeutics to treat cardiac failure has generated significant interest since the initial introduction of stem cell-based technologies. However, the methods to quickly and robustly direct stem cell differentiation towards cardiac cell types have been limited by a reliance on recombinant growth factors to provide necessary biological cues. We report here the use of dorsomorphin homologue 1 (DMH1), a second-generation small molecule BMP inhibitor based on dorsomorphin, to efficiently induce beating cardiomyocyte formation in mouse embryonic stem cells (ESCs) and to specifically upregulate canonical transcriptional markers associated with cardiac development. DMH1 differs significantly from its predecessor by its ability to enrich for pro-cardiac progenitor cells that respond to late-stage Wnt inhibition using XAV939 and produce secondary beating cardiomyocytes. Our study demonstrates the utility of small molecules to complement existing in vitro cardiac differentiation protocols and highlights the role of transient BMP inhibition in cardiomyogenesis.

3 . Kirby CA, Cheung A, Fazal A, Shultz MD, Stams T.,Structure of human tankyrase 1 in complex with small-molecule inhibitors PJ34 and XAV939.,Acta Crystallogr Sect F Struct Biol Cryst Commun. 2012 Feb 1;68(Pt 2):115-8. Epub 2012 Jan 21.
Abstract
The crystal structures of tankyrase 1 (TNKS1) in complex with two small-molecule inhibitors, PJ34 and XAV939, both at 2.0 ? resolution, are reported. The structure of TNKS1 in complex with PJ34 reveals two molecules of PJ34 bound in the NAD(+) donor pocket. One molecule is in the nicotinamide portion of the pocket, as previously observed in other PARP structures, while the second molecule is bound in the adenosine portion of the pocket. Additionally, unlike the unliganded crystallization system, the TNKS1-PJ34 crystallization system has the NAD(+) donor site accessible to bulk solvent in the crystal, which allows displacement soaking. The TNKS1-PJ34 crystallization system was used to determine the structure of TNKS1 in complex with XAV939. These structures provide a basis for the start of a structure-based drug-design campaign for TNKS1.

4 . Li Z, Yamauchi Y, Kamakura M, Murayama T, Goshima F, Kimura H, Nishiyama Y. ,Herpes simplex virus requires poly(ADP-ribose) polymerase activity for efficient replication and induces extracellular signal-related kinase-dependent phosphorylation and ICP0-dependent nuclear localization of tankyrase 1. J Virol. 2012 Jan;86(1):492-503. Epub 2011 Oct 19.
Abstract
Tankyrase 1 is a poly(ADP-ribose) polymerase (PARP) which localizes to multiple subcellular sites, including telomeres and mitotic centrosomes. Poly(ADP-ribosyl)ation of the nuclear mitotic apparatus (NuMA) protein by tankyrase 1 during mitosis is essential for sister telomere resolution and mitotic spindle pole formation. In interphase cells, tankyrase 1 resides in the cytoplasm, and its role therein is not well understood. In this study, we found that herpes simplex virus (HSV) infection induced extensive modification of tankyrase 1 but not tankyrase 2. This modification was dependent on extracellular signal-regulated kinase (ERK) activity triggered by HSV infection. Following HSV-1 infection, tankyrase 1 was recruited to the nucleus. In the early phase of infection, tankyrase 1 colocalized with ICP0 and thereafter localized within the HSV replication compartment, which was blocked in cells infected with the HSV-1 ICP0-null mutant R7910. In the absence of infection, ICP0 interacted with tankyrase 1 and efficiently promoted its nuclear localization. HSV did not replicate efficiently in cells depleted of both tankyrases 1 and 2. Moreover, XAV939, an inhibitor of tankyrase PARP activity, decreased viral titers to 2 to 5% of control values. We concluded that HSV targets tankyrase 1 in an ICP0- and ERK-dependent manner to facilitate its replication.

5 . Huang SM et al. Tankyrase inhibition stabilizes axin and antagonizes Wnt signalling. Nature. 2009 Oct 1;461(7264):614-20.
Abstract
The stability of the Wnt pathway transcription factor beta-catenin is tightly regulated by the multi-subunit destruction complex. Deregulated Wnt pathway activity has been implicated in many cancers, making this pathway an attractive target for anticancer therapies. However, the development of targeted Wnt pathway inhibitors has been hampered by the limited number of pathway components that are amenable to small molecule inhibition. Here, we used a chemical genetic screen to identify a small molecule, XAV939, which selectively inhibits beta-catenin-mediated transcription. XAV939 stimulates beta-catenin degradation by stabilizing axin, the concentration-limiting component of the destruction complex. Using a quantitative chemical proteomic approach, we discovered that XAV939 stabilizes axin by inhibiting the poly-ADP-ribosylating enzymes tankyrase 1 and tankyrase 2. Both tankyrase isoforms interact with a highly conserved domain of axin and stimulate its degradation through the ubiquitin-proteasome pathway. ...