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Published March 2014 | Supplemental Material + Published
Journal Article Open

F-box Protein FBXL16 Binds PP2A-B55α and Regulates Differentiation of Embryonic Stem Cells along the FLK1+ Lineage


The programmed formation of specific tissues from embryonic stem cells is a major goal of regenerative medicine. To identify points of intervention in cardiac tissue formation, we performed an siRNA screen in murine embryonic stem cells to identify ubiquitin system genes that repress cardiovascular tissue formation. Our screen uncovered an F-box protein, Fbxl16, as a repressor of one of the earliest steps in the cardiogenic lineage: FLK1+ progenitor formation. Whereas F-box proteins typically form SCF ubiquitin ligases, shotgun mass spectrometry revealed that FBXL16 instead binds protein phosphatase 2A (PP2A) containing a B55 specificity subunit (PP2A^(B55)). Phosphoproteomic analyses indicate that FBXL16 negatively regulates phosphorylation of the established PP2AB55 substrate, vimentin. We suggest that FBXL16 negatively regulates the activity of B55α-PP2A to modulate the genesis of FLK1+ progenitor cells.

Additional Information

© 2014 The American Society for Biochemistry and Molecular Biology, Inc. Received June 26, 2013, and in revised form, December 20, 2013; Published, MCP Papers in Press, January 5, 2014. N.H. is a recipient of American Heart Association Scientist Development Grant 10SDG3290029. This work was supported in part by HHMI. The Proteome Exploration Laboratory is supported by the Gordon and Betty Moore Foundation through Grant No. GBMF775 and the Beckman Institute. We thank Richard Lee and Janet Rossant for providing the αMHC and Flk1 reporter murine ESC lines. We also thank Shirley Pease and members of the Caltech Transgenic and Knockout Core Facility for assistance with murine ESC culture. We also thank Rochelle Diamond and Diana Perez from the Caltech Core Facility for Flow Cytometry for assistance with FACS analysis and Nathan Pierce for his assistance with in vitro protein expression. R.J.D. is an Investigator of the Howard Hughes Medical Institute. Author contributions: N.H. and R.J.D. designed research; N.H., C.M.R., J.B., J.A., R.L.G., and M.J.S. performed research; N.H., C.M.R., and J.B. contributed new reagents or analytic tools; N.H., C.M.R., J.B., S.H., J.J.C., and R.J.D. analyzed data; N.H. and R.J.D. wrote the paper.

Attached Files

Published - Mol_Cell_Proteomics-2014-Honarpour-780-91.pdf

Supplemental Material - mcp.M113.031765-1.pdf

Supplemental Material - mcp.M113.031765-10.zip

Supplemental Material - mcp.M113.031765-11.zip

Supplemental Material - mcp.M113.031765-12.zip

Supplemental Material - mcp.M113.031765-2.pdf

Supplemental Material - mcp.M113.031765-3.pdf

Supplemental Material - mcp.M113.031765-4.pdf

Supplemental Material - mcp.M113.031765-5.xlsx

Supplemental Material - mcp.M113.031765-6.xlsx

Supplemental Material - mcp.M113.031765-7.xlsx

Supplemental Material - mcp.M113.031765-8.zip

Supplemental Material - mcp.M113.031765-9.zip


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August 19, 2023
October 26, 2023