Our previous studies have shown that serotonin (5-hydroxytryptamine; 5-HT) is a growth factor for hematopoietic stem/progenitor cells. In this study, we proposed a possible mechanism: 5-HT may enhance megakaryopoiesis and proplatelet formation via Erk1/2 pathway and cytoskeleton reorganization. Here, 5-HT 2B R was first identified in megakaryocytic cells. 5-HT also promoted the megakaryocytes (MKs) proliferation and reduced the cell apoptosis via the activation of 5-HT 2B R and Akt pathway. The effects were reduced by the 5-HT 2B R inhibitor ketanserin. The effect of 5-HT on proplatelet formation in bone marrow MKs were further confirmed: the 5-HT treated group had more proplatelet bearing MKs compared with the control group. To determine whether 5-HT has effects on cytoskeleton reorganization of MKs, and whether these effects could be reduced by ketanserin or Erk1/2 inhibitor PD98059, MKs were stained with the F-actin specific binder rhodamine-phalloidin. The polymerized actin level was lower in the control group than the 5-HT group and was distributed throughout the cytoplasm with occasional aggregations. Our data demonstrated that Erk1/2 was activated in MKs treated with 5-HT. This study suggests that 5-HT has a potent effect on platelet formation and this effect is likely mediated via 5HT 2B R with subsequent activation of p-Erk1/2 and consequent F-actin reorganization and proplatelet formation. We also demonstrated that melatonin, the metabolite of 5-HT, exerts a protective effect on MK and platelet recovery in the irradiated mouse model. This study suggested that 5-HT plays an important role in platelet formation via 5HT 2B R, p-Erk1/2, and F-actin reorganization.
Cysteine (Cys) plays an important role in many physiological
activities
of human beings. Various diseases are always accompanied by abnormal
levels of Cys. A series of Cys-responsive probes were recently developed.
However, most fluorescent probes have many disadvantages and exhibit
poor in vivo imaging. Therefore, a near-infrared
fluorescence (NIRF)/photoacoustic (PA) dual-mode probe with high selectivity
and sensitivity (limit of detection = 10.6 nM) toward Cys was developed
in this study. The new Probe I interacted with Cys to activate NIRF/PA
signals, detecting Cys in vitro with a large emission
wavelength (851 nm) and Stokes shift (191 nm), monitoring the occurrence
of liver cancer in vivo. This work not only presented
an effective NIRF/PA dual-mode dicyanoisophorone probe for the first
time in the imaging of Cys but also provided a comprehensive and accurate
tool for detecting different analytes and tumors in deeper tissues,
which could be conducive to the early diagnosis of diseases.
Leucine aminopeptidase (LAP) is involved in tumor cell proliferation, invasion, and angiogenesis, which is a well-known tumor marker. In recent years, chemiluminescence has been widely used in the field of...
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