Abstract 13742: The Role of PDGF on F-actin Reorganizatio and Proplatelet Formation via PDGF beta-receptors and Erk/akt Pathways
Introduction: Our previous study demonstrated that Platelet-derived growth factor (PDGF) has a promoting effect on thrombopoiesis in an irradiated-mice model (Ye et al, Haematologica, 2010).
Hypothesis: PDGF may enhance platelet function and number via PDGFR and Erk/Akt pathways.
Methods: PDGF receptors were identified on platelets and megakaryocytic cells (MKs) by ELISA, flow cytometry and immunocytochemical staining.
Results: Both PDGFR subtype were identified on platelets and MKs; levels of PDGF beta-receptors exceeded that of alpha-receptors. PDGF-BB significantly stimulated MKs proliferation; this mitogenic effect was partially neutralized by antibodies directed against the PDGF beta-receptors. Western blot also determine that these receptors mediate PDGF-BB-inducible expression of c-fos. In MKs apoptotic model, PDGF had a similar anti-apoptotic effect as TPO. We demonstrated that PDGF activated the Akt pathway, while addition of imatinib mesylate reduced p-Akt expression, suggesting that the PDGF-initiated protective effect is likely to be mediated via PDGF receptors with subsequent activation of the Akt pathway. PDGF also promoted proplatelet formation in MKs and this effect was reduced by PDGFR antibodies. In PDGF-BB and TPO groups had more proplatelet bearing MKs; Proplatelet bearing MKs in PDGF-BB treatment group was (15 % ± 3.2), and in TPO group was (18 % ± 2.5) in 200 MKs, which were significantly more than the control group (7 % ± 2.6) (n=5). Whether PDGF has an effect on cytoskeleton reorganization of MKs, and whether the effect can be reduced by Erk1/2 inhibitor PD98059, MKs were stained with F-actin specific binder rhodamine-phalloidin. We observed that polymerized actin level is lower in control group refer to PDGF-BB group and distributed throughout the cytoplasm with occasionally few aggregation. In contrast, polymerization actin level was higher in PDGF-BB group. Adding PD98059, the fluorescence intensity was reduced (n=5).
Conclusions: Our data demonstrated that treated with PDGF-BB for 30 minutes Erk1/2 was activated in MKs. This study suggests that PDGF has a potent effect on F-actin reorganization and proplatelet formation via PDGF beta-receptors, p-ERK1/2 or p-Akt pathway.
Author Disclosures: M. Yang: Research Grant; Significant; National Natural Science Foundation of China (81270580). Y. Cheng: None. J. Ye: Research Grant; Modest; National Natural Science Foundation of China (81200345). E. Liang: None. L. Zhou: None. Q. Lian: None.
- © 2014 by American Heart Association, Inc.