Department of Biochemistry, Stanford University School of Medicine, Stanford, United States; Department of Medicine, Stanford University School of Medicine, Stanford, United States
Ramin Dubey
Department of Biochemistry, Stanford University School of Medicine, Stanford, United States; Department of Medicine, Stanford University School of Medicine, Stanford, United States
Leif R Neitzel
Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, United States
Ofelia Tacchelly-Benites
Department of Molecular and Systems Biology and the Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, Hanover, United States
Eungi Yang
Department of Molecular and Systems Biology and the Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, Hanover, United States
Caleb D Marceau
Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, United States
Eric M Davis
Department of Molecular Cellular, and Developmental Biology, University of Colorado, Boulder, Boulder, United States
Bhaven B Patel
Department of Biochemistry, Stanford University School of Medicine, Stanford, United States; Department of Medicine, Stanford University School of Medicine, Stanford, United States
Zahra Bahrami-Nejad
Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, United States
Kyle J Travaglini
Department of Biochemistry, Stanford University School of Medicine, Stanford, United States
Yashi Ahmed
Department of Molecular and Systems Biology and the Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, Hanover, United States
Ethan Lee
Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, United States
Jan E Carette
Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, United States
Department of Biochemistry, Stanford University School of Medicine, Stanford, United States; Department of Medicine, Stanford University School of Medicine, Stanford, United States
The comprehensive understanding of cellular signaling pathways remains a challenge due to multiple layers of regulation that may become evident only when the pathway is probed at different levels or critical nodes are eliminated. To discover regulatory mechanisms in canonical WNT signaling, we conducted a systematic forward genetic analysis through reporter-based screens in haploid human cells. Comparison of screens for negative, attenuating and positive regulators of WNT signaling, mediators of R-spondin-dependent signaling and suppressors of constitutive signaling induced by loss of the tumor suppressor adenomatous polyposis coli or casein kinase 1α uncovered new regulatory features at most levels of the pathway. These include a requirement for the transcription factor AP-4, a role for the DAX domain of AXIN2 in controlling β-catenin transcriptional activity, a contribution of glycophosphatidylinositol anchor biosynthesis and glypicans to R-spondin-potentiated WNT signaling, and two different mechanisms that regulate signaling when distinct components of the β-catenin destruction complex are lost. The conceptual and methodological framework we describe should enable the comprehensive understanding of other signaling systems.
