RESUMO
Objective To explore the relative signal transduction pathway of angelica polysaccharide(APS) inducing K562 cells toward erythroid differentiation. Methods K562 cells were divided into control group and ASP group, the control group cells were routinely cultured and APS group cells were treated with APS(final concentration is 100-500mg/L). By using of benzidine staining and spectrophotometry, the characteristics of erythroid differentiation of K562 cell induced by APS were detected;By using of laser confocal microscopy, the distribution of JAK_2 and STAT_5 in K562 cells was observed;By using of Western blotting, the expression of JAK_2 and STAT_5 in nucleus and cytoplasm of K562 cells was detected, By using of imm～uno～pre～cipi～ta～tion, the phosphorylation change of JAK_2 in cytoplasm was tested. Results After being induced by APS, the benzidine staining positive rate of K562 was increased.With increasing the concentration of APS, hemoglobin synthesis in K562 cells was promoted accordingly. After being cultured for 12 hours, 24 hours and 48 hour, the expression of STAT_5 in nucleus of K562 cells induced by APS was significantly higher than that of control group, however, expression of STAT_5 in cytoplasm of K562 cell induced by APS was obviously lower. The expression of JAK_2 in K562 cells was not different between APS group and control group, but the JAK_2 phosphorylation level of APS group was much higher than that of control group.Conclusion APS can induce erythroid differentiation of K562 cells, and the mechanisms may be that APS can promote the phosphorylationthe of JAK_2, then stimulating nuclear translocation of STAT_5.
RESUMO
<p><b>OBJECTIVE</b>To investgate the signal transduction and regulation in erythropoiesis by angelica polysaccharides (APS) to clarify the mechanism for APS promoting hematopoiesis.</p><p><b>METHOD</b>The mononuclear cells were isolated from foetus umbilic cord blood (mononuclear cells, MNCs), after MNCs were incubated in the presence of APS group (APS 200 mg x L(-1)) and control group for 24 h, the cells were stimulated with Epo (5 U x mL(-1)) for 0, 2, 5, 30 min, respectively. STAT5 was measured by ICC and laser confocal scanning microscope. JAK2, STAT5 in nucleus and cytoplasm were measured by western-blotting-ECL.</p><p><b>RESULT</b>Angelica polysaccharide cooperated with Epo has significant impact on the expression of STAT5. The expression of STAT5 has significant difference between APS group and the control group at 4 time points. JAK2, STAT5 expressed in cytoplasm and nuclear of APS group significantly increased as compared to those of control group, and they expressed the strongest at 5 min.</p><p><b>CONCLUSION</b>JAK2, STAT5 signal transduction molecule plays an important role in the effect of APS cooperated with Epo on promoting hematopoiesis.</p>