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. Author manuscript; available in PMC: 2011 Sep 1.
Published in final edited form as: Stem Cells. 2010 Sep;28(9):1476–1486. doi: 10.1002/stem.470

Figure 6. SHP-1 is responsible for the regulation of c-Myc expression.

Figure 6

(A) Phosphorylated Stat3 and c-Myc were analyzed by immunoblotting analysis from mESCs transiently transfected with Zap70 expressing plasmid for 48 hrs. Expression of Zap70 was confirmed by RT-PCR. (B) siSHP-1 or siCont were cotransfected with Zap70 expressing plasmid into mESCs for 48 hrs. Zap70 and SHP-1 expression were analyzed by RT-PCR (bottom panel). Phospho-Stat3 and c-Myc expression in each condition were analyzed by immunoblotting (IB: Top panel). (C) Alkaline phosphatase activity was analyzed from wild type, Zap70KD and mESCs transfected with Zap70 expressing plasmid after LIF-starved for 24 h. *, p < 0.05. (D) Proposed model of Zap70 function in mESCs. Zap70 is a negative regulator of Jak/Stat3 signaling pathway. Interaction of Zap70 with SHP-1 activates SHP-1 phosphatase to suppress Jak/Stat3 signals and subsequent c-Myc expression to maintain the balanced stemness of ESCs. Upregulation of LIFR expression is another mechanism by which Zap70 regulates the balance of self-renewal and pluripotency in mESCs. Abbreviations: Cont, transient expression of GFP; TE, transient expression of Zap70; KD, stable Zap70 knockdown mESC cell line; siSHP1, siRNA targeting SHP-1; siCont, non-specific siRNA