| Shp-2, a widely expressed cytoplasmic tyrosine phosphatase with two src-homology 2(SH2) domains,has received much attention in the signal transduction field recently.Shp-2 was found to interact physically with a variety of ligand-actived receptor protein tyrosine kinases,R-PTKs(5-7).This interaction is apparently mediated through specific recognition of a phosphotyrosine (pTyr) site on areceptor by the SH2 domains of the phosphatase.Shp-2 might be positively required for signal transduction of growth factor , stimulate differentiation and block proliferation.Since Fak is involved in the dynamics rather than the formation of focal adhesion,disruption of Fak dephosphorylation by the Shp-2 mutation should give rise to increased focal adhesion numbers.Physical interaction of Shp-2 with a R-PTK may not only serve to receive a signal to its cellular neighbors.As such,a localized cellular response could be precisely executed. Leukemia inhibitory factor (LIF), a member of the family of multifunctional cytokines, can inhibit the proliferation of leukemia cells, and accelerate the differentiation, such as HL-60, U937 and M1. LIF receptor is multimeric --- shares a (subunit, the low-affinity LIF receptor (gp190), and an additional subunit, IL-6 related signal transducer-gp130. LIF receptor initiates signaling by inducing heterodimerization of gp130 with LIF receptor (component LIFR).In our study,Shp-2(c＞s)is control, in which cypress instead of cysteine of the N-terminal SH2 domain of Shp-2. The SH2 domain shared by kinases and phosphatases directs opposite biochemical reactions,therefor, Shp-2(c＞s)could bind ligand and does not have activation of catalysis.After Shp-2 and Shp-2(c＞s)wereseparately transfected into human leukemia line HL-60 cells with LipofectAmine,Shp-2 and Shp-2(c＞s)were expressed on the membrane of HL-60.Then,to investigate differentiation and proliferation functions of the cell with LIF stimulation.we detected the level of expression of PCNA by polymerase chain reaction,western blotting and immunobiochemistry.we found that higher level of expression of PCNA was determined in the group of HL-60,the group of HL-60 with IL-11 stimulation and the group of HL-60 with LIF stimulation compared with the groups of Shp-2 and Shp-2(c＞s) with same stimulation.the group of HL-60 with LIF stimulation,the group of Shp-2 with LIF stimulation and the group of Shp-2(c＞s) with LIF stimulation were lower than the other group of HL-60,Shp-2 and Shp-2(c＞s).It suggests that the lower level of expression of PCNA was determined in the groups of Shp-2 and Shp-2(c＞s) compared with the groups of HL-60,and it is lowest in the groups with LIF stimulation.Meanwhile,expression level of CD15 was also detected by immunobiochemistry and flow cytometry.It indicates that the level of the groups of Shp-2 and Shp-2(c＞s) were higher than the corresponding group of HL-60.thereinto,the group of Shp-2 with LIF stimulation was signally higher than the groups of Shp-2 without LIF stimulation,the groups of Shp-2(c＞s) and HL-60 with LIF stimulation were lightly higher than the corresponding group of Shp-2(c＞s) and HL-60.It suggested that signally higher expression level of CD15 in the group of Shp-2 with LIF stimulation was signally than the groups of Shp-2 without LIF stimulation.the above results demonstrated:when the expression of Shp-2 strengthen in the cytoplasm,the proliferation of HL-60 was signally inhibited.the groups of HL-60,Shp-2 and Shp-2(c＞s) with LIF stimulation were more restrained,but the difference in the groups of HL-60,Shp-2 and Shp-2(c＞s) were same.It suggests that the connection between Shp-2 and LIF in HL-60 proliferation may not be evidenced.in the groups of Shp-2 and Shp-2(c＞s) the differentiation could be accelerate,the level of accelerating in the Shp-2(c＞s) is light than in Shp-2.But with LIF stimulation,the differentiation in the Shp-2 was signally strengthen.It suggeststhat the mutation of the N-terminal SH2 domain of Shp-2 could affect the...
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