Abstract 11248: 5-HT Enhances Proplatelet Formation via p-ERK1/2 Pathway and F-actin Reorganization
Serotonin (5-HT) has been recently identified as a novel growth factor for many cell types. We have showed that 5-HT is a growth factor for megakaryocytic progenitor (Yang et al, Stem Cells, 2007). We further proposed a possible mechanism of 5-HT on platelet formation: 5-HT may enhance proplatelet formation and actin re-organization via 5-HT2BR and p-ERK1/2 pathway. Here, 5-HT2BR were firstly identified in Megakaryocytic cell line Meg-01. 5-HT also promoted proplatelet formation in these cells and this effect could be reduced by 5-HT2BR inhibitor ketanserin. Effects of 5-HT in human BM megakaryocytes (MK) was further conformed: in 5-HT (200nM) and TPO (50 ng/ml) groups had more proplatelet bearing MKs; in 200 MKs, proplatelet bearing MKs in 5-HT treatment group was (12 % ± 4.9), and in TPO group was (15 % ± 1.5), which were significantly more than the control group (6 % ± 3.6) (n=4). To determine whether 5-HT has effects on cytoskeleton reorganization of MKs, and whether the effect can be reduce by ketanserin or ERK1/2 inhibitor PD98059, Meg-01 cells were staining with F-actin specific binder rhodamine-phalloidin. We observed that polymerized actin level is lower in control group refer to 5-HT group and distributed throughout the cytoplasm with occasionally few aggregation. In contrast, polymerization actin level was higher in 5-HT group. Adding ketanserin and PD98059, the fluorescence intensity was reduced. TPO group was much weaker compared with 5-HT group. Our data demonstrated that treated with 5-HT for 30 minutes ERK1/2 was activated in Meg-01 cells. The adding of ketanserin to 5-HT cultures nullified the effect of 5-HT (p=0.014, n=6). This study suggests that 5-HT has a potent effect on platelet formation. This effect is likely mediated via 5HT2B receptors with subsequent activation of p-ERK1/2, which leads to F-actin reorganization and proplatelet formation.
- © 2013 by American Heart Association, Inc.