Sodium nitrophenolate mediates brassinosteroids signaling to enhance cold tolerance of cucumber seedling

Cold stress (CS) significantly limits cucumber yield. However, it remains unclear whether and how sodium nitrophenolate (CSN) regulates plant responses to cold stress. Here, H2O, CSN, 24-epibrassinolide (EBR), and CSN + EBR were sprayed on cucumber seedlings before or after CS, and on control plants. We found that CSN, EBR, or EBR + CSN pre-treatment improved seedling growth under normal conditions (control condition) and cold tolerance under CS conditions. EBR pre-treatment promoted the expression of approximately half of the genes involved in BR synthesis and signaling and CsICE-CsCBF-CsCOR under CS. However, CSN pre-treatment promoted almost all the expression of BR synthesis and signaling genes, and CsICE-CsCBF-CsCOR genes, which showed the highest expression in early CS, remarkably improving the cold tolerance of cucumber. Interestingly, EBR and CSN had a superimposed effect on the expression of BR synthesis and signaling and CsICE-CsCBF-CsCOR genes, which rapidly increased their expression under normal temperature. Spraying EBR after CS accelerated seedling recovery, whereas CSN had the opposite effect. However, spraying CSN combined with EBR accelerated the recovery of CS-injured seedlings and was better than spraying EBR alone. Although CS-injured seedlings were negatively influenced by CSN, pre-treatment with CSN accelerated seedling growth and increased cold tolerance, suggesting that the effect of CSN was related to whether the seedlings were damaged by CS. In conclusion, we firstly found that CSN enhanced cold tolerance by activating BR signaling, contributing to the gene expression of ICE-CBF-COR and that CSN + EBR contributed to cold tolerance and CS-injured seedling recovery in cucumber.

[Effect of zoledronate on the osteoclast adhesion and gene expression of integrin α(v) and β3]

OBJECTIVE

To explore the effect of zoledronate (ZOL) on the osteoclast adhesion and expression of integrin α(v) and β3 in vitro.

METHODS

Mice RAW264.7 cells were used for osteoclast differentiation in vitro, and osteoclastogenesis was examined by tartrate-resistant acid phosphatase (TRAP) staining and dentin resorption lacunae examination. The cells were then divided into 2 groups, the control group and ZOL treatment group (treated with 1 x 10(-6) mol · L(-1) ZOL for 2 d). The adhesion ability of osteoclasts and mRNA and the protein expressions of integrin α(v) and β3 were examined by crystal violet staining, real-time fluorescence quantitative polymerase chain reaction, Western blot analysis, and immunofluorescent chemistry.

RESULTS

TRAP staining and dentin resorption lacunae examination revealed the formation of multi-nuclear osteoclasts. ZOL treatment significantly decreased the adhesion ability of osteoclasts (P < 0.01). In the ZOL-treated group, the mRNA levels of integrin α(v) and β3 were 0.66 ± 0.05 and 0.59 ± 0.08, respectively. In the control group, the mRNA levels of integrin α(v) and β3, were 1.01 ± 0.01 and 1.01 ± 0.02, respectively; these values were higher than those in the ZOL-treated group (P < 0.01). The protein level of integrin α(v) and β3 in the ZOL-treated group (31,934.84 ± 112.91 and 18,812.79 ± 194.13) was downregulated by approximately 39.19% and 40.17%, respectively, compared with those in the control group (52,517.81 ± 211.72 and 31,441.93 ± 456.87) (P < 0.01). Immunofluorescent examination showed that the fluorescent intensities of integrin α(v) and β3 in the ZOL-treated group (9.491 ± 0.748 and 4.744 ± 0.759) were also significantly decreased compared with those in the control group (15.159 ± 1.143 and 11.418 ± 1.095) (P < 0.01).

CONCLUSION

ZOL significantly inhibits osteoclast adhesion and downregulates integrin α(v) and β3, expression, thus contributing to the ZOL-induced inhibition of osteoclast- mediated bone resorption.