Figure 4. Preplatelets reversibly... | Rockefeller University Press

Figure 4.

$Figure 4. Preplatelets reversibly convert into proplatelets using microtubule-based forces. (A and B) Proplatelet-enriched fractions were probed with a rabbit polyclonal antibody against detyrosinated tubulin and analyzed by immunofluorescence microscopy for different-sized objects. Samples were incubated at 37°C (normal control), 4°C for 1 h, or 4°C for 1 h and returned to 37°C for 1 h. All values were normalized to the 37°C controls. (A) Depolymerization of tubulin at 4°C shifted the proplatelet population into preplatelet forms. *, P < 0.05; **, P < 0.01. Arrows indicate values compared and significance level of difference. (B) The proplatelet population returned to normal upon repolymerization of tubulin at 37°C. Data were subject to one-way ANOVA for three independent samples and Tukey HSD analysis. (C) Released proplatelet/platelet fraction from second gradient sedimentation probed with a rabbit polyclonal antibody against detyrosinated tubulin and analyzed by immunofluorescence microscopy for different-sized objects. Distribution of proplatelet and preplatelet forms after 1 h in culture with 5 µM taxol (promotes microtubule polymerization; left), a vector control (middle), or 5 µM nocodazole (promotes microtubule depolymerization; right). Microtubule stabilization and depolymerization shifted the population toward proplatelet and preplatelet forms, respectively. (D) Representative pictures of cultured intermediates after taxol (proplatelet) or nocodazole (preplatelet) incubations.$

Preplatelets reversibly convert into proplatelets using microtubule-based forces. (A and B) Proplatelet-enriched fractions were probed with a rabbit polyclonal antibody against detyrosinated tubulin and analyzed by immunofluorescence microscopy for different-sized objects. Samples were incubated at 37°C (normal control), 4°C for 1 h, or 4°C for 1 h and returned to 37°C for 1 h. All values were normalized to the 37°C controls. (A) Depolymerization of tubulin at 4°C shifted the proplatelet population into preplatelet forms. *, P < 0.05; **, P < 0.01. Arrows indicate values compared and significance level of difference. (B) The proplatelet population returned to normal upon repolymerization of tubulin at 37°C. Data were subject to one-way ANOVA for three independent samples and Tukey HSD analysis. (C) Released proplatelet/platelet fraction from second gradient sedimentation probed with a rabbit polyclonal antibody against detyrosinated tubulin and analyzed by immunofluorescence microscopy for different-sized objects. Distribution of proplatelet and preplatelet forms after 1 h in culture with 5 µM taxol (promotes microtubule polymerization; left), a vector control (middle), or 5 µM nocodazole (promotes microtubule depolymerization; right). Microtubule stabilization and depolymerization shifted the population toward proplatelet and preplatelet forms, respectively. (D) Representative pictures of cultured intermediates after taxol (proplatelet) or nocodazole (preplatelet) incubations.