Efficient sucrose loading in rubber-producing cells (laticifer cells) is essential for retaining rubber productivity in Hevea brasiliensis, but the molecular mechanisms underlying the regulation of this process remain unknown. Here, we functionally characterized a putative Hevea SUT member, HbSUT3, mainly in samples from regularly exploited trees. When expressed in yeast, HbSUT3 encodes a functional sucrose transporter that exhibits high sucrose affinity with a Km value of 1.24 mM at pH 4.0, and possesses features typical of sucrose/H + symporters. In planta, when compared to the expression of other Hevea SUT genes, HbSUT3 was found to be the predominant member expressed in the rubber-containing cytoplasm (latex) of laticifers. The comparison of HbSUT3 expression among twelve Hevea tissues demonstrates a relatively tissuespecific pattern, i.e. expression primarily in the latex and in female flowers. HbSUT3 expression is induced by the latex stimulator Ethrel (an ethylene generator), and relates to its yield-stimulating effect. Tapping (the act of rubber harvesting) markedly increased the expression of HbSUT3, whereas wounding alone had little effect. Moreover, the expression of HbSUT3 was found to be positively correlated with latex yield. Taken together, our results provide evidence favouring the involvement of HbSUT3 in sucrose loading into laticifers and in rubber productivity.

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Ezrin is highly expressed in metastatic tumors and is involved in filopodia formation as well as promotion of tumor metastasis. Thus, Ezrin may serve as a potential target for anti-metastatic therapy. This study demonstrates that berberine reduces filopodia formation of a nasopharyngeal carcinoma (NPC) cell line, 5-8F, at non-cytotoxic concentrations. Furthermore, invasion and motility of 5-8F cells are decreased in a dose-and time-dependent manner, resulting in 73.0% invasion and 67.0% motility inhibition at 20 M. The inhibitory effects of berberine on 5-8F cell metastasis were further confirmed in a mouse model of metastasis. Berberine treatment in vivo resulted in a 51.1% inhibition of tumor metastasis to the lymph nodes and decreased Ezrin phosphorylation at threonine 567 in metastatic samples. Berberine suppressed the presence of phosphorylated Ezrin (phospho-Ezrin) in a dose-and time-dependent manner but had no effect on total Ezrin protein expression at non-cytotoxic concentrations. Furthermore, the inhibitory effects of berberine on phospho-Ezrin were dependent on the suppression of Rho kinase activity. Reduction of Ezrin phosphorylation at Thr 567 by berberine was associated with its inhibitory effect on filopodia formation in 5-8F cells. However, berberine did not effectively inhibit the motility and invasion of NPC cells containing Ezrin Thr 567 mutants. These results confirm that berberine inhibits Ezrin phosphorylation at Thr 567 . Nonetheless, berberine reduces motility and invasion of cells and inhibits tumor metastasis. The reduction of Rho kinase-mediated Ezrin phosphorylation mediated by berberine may be a novel anti-metastatic pathway in NPC 5-8F cells.