Fig. 7: The interaction of zyxin with VASP is required for zyxin-mediated GPIbα expression and platelet production.

A Cartoons for the constructs of zyxin mutants lacking α-actinin and NMMHC-IIA (Zyx^43–564), and VASP (Zyx^4F > A) binding sites. NES, nuclear export signals. B Zyx^−/− FL HPCs were infected with adenoviruses expressing WT zyxin (Zyx^1–564), zyxin mutants Zyx^43-564 and Zyx^4F > A, and vehicle vector (control). The expression levels of WT zyxin and zyxin mutants were determined by Western blot with an anti-flag tag antibody. The green fluorescence (GFP) indicates the introduction of the plasmids into HPC-derived MKs. Blots are representative of five independent experiments. C–F The expression of CD41 (C) and GPIbα (D) on culture-derived MKs was determined on day 4 by flow cytometry. The presence of CD41⁺ (E) and GPIbα⁺ (F) platelet-sized particles released from culture-derived MKs was determined on day 5 by flow cytometry. FC, fold-change. Data are from five independent experiments, and means are indicated by horizontal lines in (B–F). *P < 0.05, **P < 0.01, compared with control by one-way ANOVA followed by Dunnett’s post hoc test. NS, not significant. G Representative fluorescent microscopy images of proplatelet formation from five independent experiments (original magnification ×200). Scale bar: 40 μm. Proplatelet protrusions were indicated with arrows.