Panaxdiol saponins component promotes hematopoiesis by regulating GATA transcription factors of intracellular signaling pathway in mouse bone marrow.

Background: Our research team has identified a biological active component, panaxadiol saponins component (PDS-C) isolated from total saponins of panax ginseng as a potential targeted drug for treating hemocytopenia. PDS-C possesses dual activities, namely that of promoting hematopoiesis and regulating immune function. Our study is to observe effects of PDS-C on promoting hematopoiesis in normal and aplastic anemia (AA) mice, furthermore, to explore its possible mechanism. Methods: Bone marrow nucleated cells were cultured for colony forming assay of CFU-GM, CFU-E and CFU-MK in the presence of PDS-C at different concentration. The proliferation and differentiation-related genes expression profile was analyzed with DNA membrane microarray. The mRNA expression levels and protein phosphorylated state of GATA-1, GATA-2 transcription factors and AKT-1, MAPK14 protein kinases were detected by RT-qPCR and Western blot, the DNA binding activity and components of GATA-DNA complex were analyzed by EMSA and antibody gel supershift assay. Results: In response to PDS-C at 10, 25 and 50 mg/L, the bone marrow colony numbers of CFU-GM, CFU-E and CFU-MK increased significantly by 25.7%±3.1% to 42.4%±4.5% respectively in normal mice, and 29.7%±3.7% to 53.2%±7.1% in AA mice. The gene microarray profile initiated by PDS-C provided the up-regulated genes by more than 3 times, which can be classified into 11 categories according to their functions, including GATA-1, GATA-2, and AKT-1, MAPK14. The mRNA expression levels of GATA-1, GATA-2 were consistent with their gene microarray profile in PDS-C treated erythroid and megakaryocytic hematopoietic cells. Meanwhile, PDS-C could not only up-regulate expression levels of GATA-1, GATA-2 proteins, but also enhance phosphorylated activity state. Furthermore, PDS-C obviously enhanced binding activity of GATA protein with DNA in erythroid and megakaryocytic cells, and the main composition of GATA-DNA complex was GATA-2 and GATA-1. Conclusions: PDS-C displays the role to promote proliferation and induce differentiation for hematopoietic cells. Its action mechanism may involve in GATA-1, GATA-2 transcription factors, including up-regulating mRNA and protein expression, enhancing DNA binding activity, phosphorylated functional activity and up-regulating AKT-1, MAPK14 protein kinases as the upstream signaling molecule for activation GATA-1, GATA-2 respectively in hematopoietic cells.

[Apoptosis of Endothelial Cells Induced by Anti-Platelet Integrin ß3 Antibody].

OBJECTIVE: To investigate the damaging of human umbilical vein endothelial cells (HUVEC) induced by antiplatelet integrin ß3 antibodies in vitro. METHODS: The serum from 36 chronic ITP patients were collected, flow cytometry and monoclonal antibody specific immobilization of platelet antigen (MAIPA) assay were used to collect antiplatelet integrin ß3 antibodies from the serum of the patients. After HUVEC were treated by ITP patient serum (PS) containing anti-integrin ß3 antibodies, the cell damage was detected by Lactate dehydrogenase (LDH) assay, cell apoptosis was detected by flow cytometry, the expression of apoptosis-related gene Bax was detected by Reverse transcription-Quantitative real-time PCR (RT-qPCR), and expression of Apoptosis-related signaling pathway protein Akt and related protein Bax were detected by Western blot. HUVEC were treated by PS combined with Akt activator SC79, the cells damage were detected by LDH assay, apoptosis of the cells were detected by flow cytometry, the expression of apoptosis-related gene Bax was detected by RT-qPCR. RESULTS: Among 36 cases of serum from the chronic ITP patients, 5 patients' serum containing anti-integrin ß3 antibodies were collected. After HUVEC was treated by PS, the viability of LDH was significant increased（P<0.05）, so as for the apoptosis of the cells（P<0.05）, the expression of gene and protein of Bax was increased up-regulated（P<0.05）, the protein expression of pAkt was down-regulated（P<0.05）. Comparing with HUVEC cultured with PS alone, the viability of LDH of HUVEC treated by PS combined with SC79 was significantly reduced（P<0.05）, so as for the apoptosis of the cells（P<0.05）, and gene expression of Bax was significantly decreased（P<0.05）. CONCLUSION: Anti-integrin ß3 serum can cause the damage and apoptosis of HUVEC through Akt signaling pathway，the apoptotic effects of anti-integrin ß3 antibodies to HUVEC was effectively reversed by SC79.

[Differentiation of Cultivated CD45-/CD31+ Mouse Lung Side Population Cells into Vascular Smooth Muscle Cells in vitro].

OBJECTIVES: To investigate the characteristics of differentiation of lung side population cells (LSP cells)in vitro. METHODS: CD45-/CD31+ LSP cells sorted by flow cytometry were taken from mouse lung tissues and cultured for 14 d. The cultured LSP cells were observed with colony formation assay and flow cytometryin vitro. The mRNA expressions of ATP-binding cassette transporter G2 (ABCG2), smooth muscle actin (SMA) and α-smooth muscle tropomyosin (α-SMT) in both freshly isolated LSP cells and cultured LSP cells were examined. The expressions of ABCG2 and stem cell antigen 1 (Sca1) in LSP cells were detected using immunofluorescence. RT-PCR tests were performed to detect the expressions of ABCG2, SMA and α-SMT in LSP cells. RESULTS: The isolated CD45-/CD31+ lung side population cells expressed ABCG2, SMA and Sca1, but not α-SMT. A large number of LSP in aggregated state were observed after 14 d of culture. Before induction of differentiation, the CD45-/CD31+ LSP cells expressed ABCG2 and SMA, but not α-SMT. After induction of differentiation, the CD45-/CD31+ lung side population cells expressed α-SMT and SMA, but not ABCG2. CONCLUSIONS: CD45-/CD31+ LSP cells might be progenitor cells of vascular smooth muscle cells, possessing the characteristics of stem cell differentiations.