Objective: To investigate the effects of panax notoginseng saponins (PNS) on expression, regulation and phosphorylation of multiple protein kinases in mitogen activated protein kinase (MAPK) intracellular signal pathway and GATA transcription factors in hematopoietic cells, so as to explore its mechanism of proliferation and differentiation activity on hematopoiesis.
Methods: The human granulocytic HL-60, erythrocytic K562, megakaryocytic CHRF-288 and Meg-01 cell lines were treated by PNS, the positive control of K562, CHRF-288 cells treated by recombination human erythropoietin (Epo) and thrombopoietin (Tpo) respectively. The total cell lysate and nuclei protein were extracted after being treated by PNS, subsequently, analyzed by both Western blot and immune-precipitation. Meanwhile, the nuclei extract was performed for electrophoretic mobility shift assay (EMSA) by using (32)P radio labeled double-stranded GATA consensus oligonucleotide.
Results: The expression levels of kinase MEK-1, MEK-2, ERK-1, ERK-2, AKT-1, AKT-2 and PI-3K were increased by PNS treatment to different extent in four cell lines, depending on cellular heterogeneity and sensitivity to PNS, also phosphorylation of MEK-1, ERK-1 was differentially promoted by PNS respectively P<0.05, 0.01, 0.001). The expression levels of transcription factors GATA-1 and GATA-2 were increased, moreover, their DNA binding activities were raised dramatically in PNS treated K562, CHRF-288 and Meg-01 cells compared with the controls respectively (P<0.05, 0.01, 0.001). The positive control of K562, CHRF-288 cells treated by Epo or Tpo respectively also displayed up-regulation of protein kinases and GATA transcription factors respectively (P<0.05, 0.01, 0.001).
Conclusion: The results indicated that intracellular signal pathway initiated by PNS was involved in MAPK pathway and transcription factors of GATA family in hematopoietic cells. PNS displayed the role to promote proliferation and differentiation, by means of increasing expression level and phosphorylation status of multiple protein kinases, also inducing synthesis of GATA transcription factors and upregulation its DNA binding activity.