Bruton's tyrosine kinase revealed as a negative regulator of Wnt-beta-catenin signaling.
Wnts are secreted ligands that activate several receptor-mediated signal transduction cascades. Homeostatic Wnt signaling through beta-catenin is required in adults, because either elevation or attenuation of beta-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-beta-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-beta-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-beta-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 beta-catenin-mediated transcription in human colorectal cancer cells and B cells.
James
Richard G
RG
Department of Pharmacology, Howard Hughes Medical Institute, University of Washington School of Medicine, Box 357370, Seattle, WA 98195, USA.
Biechele
Travis L
TL
Conrad
William H
WH
Camp
Nathan D
ND
Fass
Daniel M
DM
Major
Michael B
MB
Sommer
Karen
K
Yi
XianHua
X
Roberts
Brian S
BS
Cleary
Michele A
MA
Arthur
William T
WT
MacCoss
Michael
M
Rawlings
David J
DJ
Haggarty
Stephen J
SJ
Moon
Randall T
RT
D000077329:Agammaglobulinaemia Tyrosine Kinase; D000818:Animals; D002460:Cell Line; D002846:Chromatography, Affinity; D006801:Humans; D013058:Mass Spectrometry; D011505:Protein-Tyrosine Kinases / Q000302:isolation & purification / Q000378:metabolism*; D015398:Signal Transduction; D051153:Wnt Proteins / Q000378:metabolism*; D051176:beta Catenin / Q000378:metabolism*
D051153:Wnt Proteins; D051176:beta Catenin; D011505:Protein-Tyrosine Kinases; D000077329:Agammaglobulinaemia Tyrosine Kinase; C000625949:BTK protein, human