Journal: The Journal of Biological Chemistry
Article Title: Activated Platelets Interfere with Recruitment of Mesenchymal Stem Cells to Apoptotic Cardiac Cells via High Mobility Group Box 1/Toll-like Receptor 4-mediated Down-regulation of Hepatocyte Growth Factor Receptor MET *
doi: 10.1074/jbc.M113.530287
Figure Lengend Snippet: Expression of HMGB1 in platelets and release upon platelet activation. A, expression of intracellular HMGB1 in resting (untreated) and activated (5 μg/ml CRP, 15 min; 50 μm ADP, 15 min) platelets was determined by immunofluorescence staining and confocal laser-scanning microscopy. An HMGB1-specific polyclonal antibody and an Alexa Fluor 488-tagged antibody (green) were used. Representative images of three independent experiments. Scale bar, 5 μm. B, HMGB1 protein levels in lysates and conditioned media derived from resting and CRP-activated platelets (5 μg/ml CRP; 5, 15, and 30 min) were deciphered by Western blot analysis, detecting HMGB1 at 25 kDa. An actin polyclonal antibody served as loading control. Statistical significance (*, p < 0.04; **, p < 0.01) of densitometric analysis of HMGB1 bands (normalized to actin) is indicated. C, HMGB1 levels in conditioned media derived from resting (untreated, 5, 15, 30 min) and activated (50 μm ADP, 5, 15, 30 min; 5 μg/ml CRP, 5, 15, 30 min) platelets were also measured by ELISA. In addition, surface expression of P-selectin (CD62P) on platelets was investigated by staining with a CD62P-specific monoclonal antibody and flow cytometry. Error bars, S.E.
Article Snippet: In other experiments, HMGB1-receptors RAGE, TLR-2, and TLR-4 were blocked on MSC prior to MSC preincubation with CM of activated platelets or recombinant HMGB1 by treatment with anti-human RAGE polyclonal antibody (20 μg/ml, goat IgG), anti-human TLR-2 monoclonal antibody (2 μg/ml, mouse IgG2b), or anti-human TLR-4 polyclonal antibody (10 μg/ml, goat IgG) (all from R&D Systems).
Techniques: Expressing, Activation Assay, Immunofluorescence, Staining, Confocal Laser Scanning Microscopy, Derivative Assay, Western Blot, Enzyme-linked Immunosorbent Assay, Flow Cytometry