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Elife. 2016 Dec 20;5. pii: e21459. doi: 10.7554/eLife.21459.

Comparative genetic screens in human cells reveal new regulatory mechanisms in WNT signaling.

Author information

1
Department of Biochemistry, Stanford University School of Medicine, Stanford, United States.
2
Department of Medicine, Stanford University School of Medicine, Stanford, United States.
3
Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, United States.
4
Department of Molecular and Systems Biology and the Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, Hanover, United States.
5
Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, United States.
6
Department of Molecular Cellular, and Developmental Biology, University of Colorado, Boulder, Boulder, United States.
7
Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, United States.

Abstract

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.

KEYWORDS:

APC; AXIN; CSNK1A1; GPC4; GPI; HAP1; HUWE1; RSPO; SERBP1; TFAP4; WNT signaling; computational biology; developmental biology; forward genetics; genetic screen; glypican; haploid cells; haploid screen; human; stem cells; suppressor screen; systems biology

PMID:
27996937
PMCID:
PMC5257257
DOI:
10.7554/eLife.21459
[Indexed for MEDLINE]
Free PMC Article

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