Phosphoproteomic analysis of human embryonic stem cells.
Protein phosphorylation, while critical to cellular behavior, has been undercharacterized in pluripotent cells. Therefore, we performed phosphoproteomic analyses of human embryonic stem cells (hESCs) and their differentiated derivatives. A total of 2546 phosphorylation sites were identified on 1602 phosphoproteins; 389 proteins contained more phosphorylation site identifications in undifferentiated hESCs, whereas 540 contained more such identifications in differentiated derivatives. Phosphoproteins in receptor tyrosine kinase (RTK) signaling pathways were numerous in undifferentiated hESCs. Cellular assays corroborated this observation by showing that multiple RTKs cooperatively supported undifferentiated hESCs. In addition to bFGF, EGFR, VEGFR, and PDGFR activation was critical to the undifferentiated state of hESCs. PDGF-AA complemented a subthreshold bFGF concentration to maintain undifferentiated hESCs. Also consistent with phosphoproteomics, JNK activity participated in maintenance of undifferentiated hESCs. These results support the utility of phosphoproteomic data, provide guidance for investigating protein function in hESCs, and complement transcriptomics/epigenetics for broadening our understanding of hESC fate determination.
Brill
Laurence M
LM
Genomics Institute of the Novartis Research Foundation, San Diego, CA 92109, USA. lbrill@burnham.org
Xiong
Wen
W
Lee
Ki-Bum
KB
Ficarro
Scott B
SB
Crain
Andrew
A
Xu
Yue
Y
Terskikh
Alexey
A
Snyder
Evan Y
EY
Ding
Sheng
S
D053595:Embryonic Stem Cells / Q000378:metabolism*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D020543:Proteome / Q000378:metabolism*; D040901:Proteomics; D015398:Signal Transduction / Q000502:physiology
D036341:Intercellular Signaling Peptides and Proteins; D010750:Phosphoproteins; D020543:Proteome; D011494:Protein Kinases