Tumor suppressor protein DAB2IP participates in chromosomal stability maintenance through activating spindle assembly checkpoint and stabilizing kinetochore-microtubule attachments

Defects in kinetochore-microtubule (KT-MT) attachment and the spindle assembly checkpoint (SAC) during cell division are strongly associated with chromosomal instability (CIN). CIN has been linked to carcinogenesis, metastasis, poor prognosis and resistance to cancer therapy. We previously reported that the DAB2IP is a tumor suppressor, and that loss of DAB2IP is often detected in advanced prostate cancer (PCa) and is indicative of poor prognosis. Here, we report that the loss of DAB2IP results in impaired KT-MT attachment, compromised SAC and aberrant chromosomal segregation. We discovered that DAB2IP directly interacts with Plk1 and its loss inhibits Plk1 kinase activity, thereby impairing Plk1-mediated BubR1 phosphorylation. Loss of DAB2IP decreases the localization of BubR1 at the kinetochore during mitosis progression. In addition, the reconstitution of DAB2IP enhances the sensitivity of PCa cells to microtubule stabilizing drugs (paclitaxel, docetaxel) and Plk1 inhibitor (BI2536). Our findings demonstrate a novel function of DAB2IP in the maintenance of KT-MT structure and SAC regulation during mitosis which is essential for chromosomal stability.     

Targeting secreted cytokine BMP9 gates the attenuation of hepatic fibrosis

Liver fibrosis is overly exuberant wound healing that leads to portal hypertension or liver cirrhosis. Recent studies have demonstrated the functions of bone morphogenetic protein 9 (BMP9) in liver fibrosis, and thus, targeting liver-specific BMP9 abnormalities will become an attractive approach for developing therapeutics to treat liver fibrosis. Here, we reveal that BMP9 serves as a valuable serum diagnostic indicator and efficient therapeutic target to attenuate liver fibrogenesis. Our analysis of biopsies from liver fibrotic patients revealed that higher BMP9 levels accompanied advanced stages of liver fibrosis. In mouse models, recombinant Bmp9 overexpression accelerated liver fibrosis, and adenovirus-mediated Bmp9 knockdown attenuated liver fibrogenesis. Intriguingly, BMP9 directly stimulated hepatic stellate cell activation via the SMAD signaling pathway to enhance hepatic fibrosis. Moreover, an inhibitory monoclonal antibody targeting Bmp9 was efficacious in treatment of mice with liver fibrosis. These observations delineate a novel model in which BMP9 directly drives SMAD/ID1 signaling in hepatic stellate cells, which modulates liver fibrogenesis development. Moreover, the findings unveil a promising surrogate biomarker for the diagnosis of hepatic fibrosis, thereby representing an efficient “BMP9 neutralization” approach in alleviating hepatic fibrosis.     

<Emphasis Type="Italic">Mesorhizobium jarvisii</Emphasis> sv. astragali as predominant microsymbiont for <Emphasis Type="Italic">Astragalus sinicus</Emphasis> L. in acidic soils,Xinyang, China

Background and aims

Common bean (Phaseolus vulgaris L.) nodulates with a wide range of rhizobia. Amongst these is Bradyrhizobium, which is inefficient but able to induce profuse nodulation on this crop. Based on this observation, we tested whether co-inoculating bradyrhizobia with a more standard common bean symbiont, Rhizobium tropici, could stimulate growth and nodulation of common bean, thus contributing to a more effective symbiosis.

Methods

Rhizobium tropici was co-inoculated with two Bradyrhizobium strains applied at three different doses (10⁴, 10⁶, and 10⁸ CFU seed^?1) under sterile conditions, and at a single dose (10⁸ CFU seed^?1) in non-sterile soil. Plant biomass, nodulation, and N accumulation in plant tissues were evaluated.

Results

Co-inoculated plants produced more nodules, and accumulated more shoot dry biomass and nitrogen than plants inoculated with R. tropici alone under gnotobiotic conditions. Significant responses were observed at the highest inoculum dose and a significant correlation between dose and shoot dry weight was observed. Co-inoculation increased biomass and N accumulation in non-sterile soil, although with a smaller magnitude.

Conclusions

Altogether, our findings suggest that the co-inoculation with bradyrhizobia contributed to an improved symbiotic interaction between R. tropici and common beans.