ESCRT-I Component VPS23A Sustains Salt Tolerance by Strengthening the SOS Module in Arabidopsis

The Salt-Overly-Sensitive(SOS)signaling module,comprising the sodium-transport protein SOS1 and the regulatory proteins SOS2 and SOS3,is well known as the central salt excretion system,which helps protect plants against salt stress.Here we report that VPS23A,a component of the ESCRT(endosomal sorting complex required for transport),plays an essential role in the function of the SOS module in conferring plant salt tolerance.VPS23A enhances the interaction of SOS2 and SOS3.In the presence of salt stress,VPS23A positively regulates the redistribution of SOS2 to the plasma membrane,which then activates the antiporter activity of SOS1 to reduce Na+accumulation in plant cells.Genetic evidence demonstrated that plant salt tolerance achieved by the overexpression of SOS2 and SOS3 dependeds on VPS23A.Taken together,our results revealed that VPS23A is a crucial regulator of the SOS module and affects the localization of SOS2 to the cell membrane.Moreover,the strong salt tolerance of Arabidopsis seedlings conferred by the engineered membrane-bound SOS2 revealed the significance of SOS2 sorting to the cell membrane in achieving its function,providing a potential strategy for crop salt tolerance engineering.

生长素介导环境信号调控植物的生长发育

植物是一类营固着生活的自养型生物,如何更好地适应周围环境对植物的生存至关重要。生长素是调控植物生长发育的重要激素之一。近年来的研究发现,生长素不仅能够响应内在的发育信号,而且能够介导各种环境信号,参与植物生长发育和生长反应的调控。该文主要从光信号、温度信号、重力信号、营养元素和金属离子信号等方面重点阐述生长素如何介导上述各种不同的环境信号,从而调控植物的生长发育。

ESCRT-I Component VPS23A Is Targeted by E3 Ubiquitin Ligase XBAT35 for Proteasome-Mediated Degradation in Modulating ABA Signaling

A myriad of abiotic stress responses in plants are controlled by abscisic acid(ABA)signaling.ABA receptors can be degraded by both the 26S proteasome pathway and vacuolar degradation pathway after processing via the endosomal sorting complex required for transport(ESCRT)proteins.Despite being essential for ABA signaling,the upstream regulators of ESCRTs remain unknown.Here,we report that the ESCRT-I component VPS23A is an unstable protein that is degraded via the ubiquitin-proteasome system(UPS).The UEV domain of VPS23A physically interacts with the two PSAP motifs of XBAT35,an E3 ubiquitin ligase,and this interaction results in the deposition of K48 polyubiquitin chains on VPS23A,marking it for degradation by 26S proteasomes.We showed that XBAT35 in plants is a positive regulator of ABA responses that acts via the VPS23A/PYL4 complex,specifically by accelerating VPS23A turnover and thereby increasing accumulation of the ABA receptor PYL4.This work deciphers how an ESCRT component is regulated in plants and deepens our understanding of plant stress responses by illustrating a mechanism whereby crosstalk between the UPS and endosome-vacuole-mediated degradation pathways controls ABA signaling.

Synthesis and characterization of dendronized hyperbranched polymers through the “A_3+B_2” approach

Dendronized hyperbranched polymer(DHP) is a new kind of polymer, which combines the advantages of dendrimers and hyperbranched polymers. In this work, two dendronized hyperbranched polymers, DHPG0 and DHPG1, were successfully prepared through the simple "A_3+B_2" type Sonogashira coupling reaction. The nonlinear optical(NLO) effects of DHPG0 and DHPG1, characterized by the d33 values, were 183 and 220 pm V^(–1) respectively, higher than those of their analogues of dendronized polymers and dendrimers, thanks to the special topological structure. Also, the obtained polymers displayed excellent solubility, good processability, and high thermal stability.

Inhibitory activity of Bifidobacterium adolescent combined with cisplatin on melanoma in mice and its mechanism

The aim of this study is to explore inhibitory activity of Bifidobacterium adolescent combined with cis-platin on the growth of melanoma(B16)in mice and the underlying mechanism.C57 mice were inoculated with B16 cancer cells to construct mouse model of melanoma and treated with bifidobacterium adolescent combined with cisplatin.Ratios of inhibitory activity on the growth of melanoma(B16)were calculated.Pathology changes of the tumor were observed by HE staining.B16 cell cycles were examined on a flow cytometer.Lymphocyte prolif-eration was measured with MTT assay and the T-cell sub-set was measured by double marked fluorescence.When bifidobacterium of 1010 cfu/L was injected,the ratio of inhibitory activity on the growth of melanoma(B16)reached 54%,which was similar to that of cisplatin group.The ratio of inhibitory activity reached 74.45%when the mice were treated by bifidobacterium combined with cis-platin.HE staining shows that bifidobacterium inhibited B16 cell proliferation and enhanced the cisplatin`s killing activity on B16 cells.The results of flow cytometry demonstrated that B16 cell proliferation was arrested at G1 stage after treatment with bifidobacterium.The B16 cell proliferation was arrested at S stage after treatment with cisplatin.The CD4+percentage increased and the difference was significant compared with the normal group after treatment with bifidobacterium,indicating that T-cell immune activity was enhanced.Treatment with bifidobacterium combined with cisplatin can enhance the inhibitory activity on the growth of melanoma(B16)of cisplatin.The mechanism of the inhibitory activity on B16 cell proliferation is correlated with the enhanced immune activity in mice.