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Sci. Signal., 26 May 2009
Vol. 2, Issue 72, p. ra25
[DOI: 10.1126/scisignal.2000230]

RESEARCH

Bruton’s Tyrosine Kinase Revealed as a Negative Regulator of Wnt–β-Catenin Signaling

Richard G. James1,2*, Travis L. Biechele1,2*, William H. Conrad1,2, Nathan D. Camp1,2, Daniel M. Fass3{dagger}, Michael B. Major1,2, Karen Sommer4, XianHua Yi5, Brian S. Roberts6, Michele A. Cleary6, William T. Arthur6, Michael MacCoss5, David J. Rawlings4, Stephen J. Haggarty3{dagger}, and Randall T. Moon1,2{ddagger}

1 Department of Pharmacology, Howard Hughes Medical Institute, University of Washington School of Medicine, Box 357370, Seattle, WA 98195, USA.
2 Institute for Stem Cell and Regenerative Medicine, University of Washington School of Medicine, Box 357370, Seattle, WA 98195, USA.
3 The Broad Institute of Harvard University and Massachusetts Institute of Technology, 7 Cambridge Street, Cambridge, MA 02141, USA.
4 Departments of Pediatrics and Immunology, Seattle Children’s Research Institute, 1900 Ninth Avenue, C9S-7, Seattle, WA 98101, USA.
5 Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA 98195, USA.
6 Rosetta Inpharmatics, LLC, a wholly owned subsidiary of Merck & Co Inc., 401 Terry Avenue N, Seattle, WA 98109, USA.

* These authors contributed equally to this work.

{dagger} Present address: Center for Human Genetic Research, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA.

Abstract: Wnts are secreted ligands that activate several receptor-mediated signal transduction cascades. Homeostatic Wnt signaling through β-catenin is required in adults, because either elevation or attenuation of β-catenin function has been linked to diverse diseases. To contribute to the identification of both protein and pharmacological regulators of this pathway, we describe a combinatorial screen that merged data from a high-throughput screen of known bioactive compounds with an independent focused small interfering RNA screen. Each screen independently revealed Bruton’s tyrosine kinase (BTK) as an inhibitor of Wnt–β-catenin signaling. Loss of BTK function in human colorectal cancer cells, human B cells, zebrafish embryos, and cells derived from X-linked agammaglobulinemia patients with a mutant BTK gene resulted in elevated Wnt–β-catenin signaling, confirming that BTK acts as a negative regulator of this pathway. From affinity purification–mass spectrometry and biochemical binding studies, we found that BTK directly interacts with a nuclear component of Wnt–β-catenin signaling, CDC73. Further, we show that BTK increased the abundance of CDC73 in the absence of stimulation and that CDC73 acted as a repressor of β-catenin–mediated transcription in human colorectal cancer cells and B cells.

{ddagger} To whom correspondence should be addressed. E-mail: rtmoon{at}u.washington.edu

Citation: R. G. James, T. L. Biechele, W. H. Conrad, N. D. Camp, D. M. Fass, M. B. Major, K. Sommer, X. Yi, B. S. Roberts, M. A. Cleary, W. T. Arthur, M. MacCoss, D. J. Rawlings, S. J. Haggarty, R. T. Moon, Bruton’s Tyrosine Kinase Revealed as a Negative Regulator of Wnt–β-Catenin Signaling. Sci. Signal. 2, ra25 (2009).

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