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Light is an important environmental factor for plant growth and development. Phytochrome B (phyB), a classical red/far-red light receptor, plays vital role in controlling plant photomorphogenesis and light-induced stomatal opening. Phytohormone abscisic acid (ABA) accumulates rapidly and triggers a series of physiological and molecular events during the responses to multiple abiotic stresses. Recent studies showed that phyB mutant synthesizes more ABA and exhibits improved tolerance to salt and cold stress, suggesting that a crosstalk exists between light and ABA signaling pathway. However, whether ABA signaling components mediate responses to light remains unclear. Here, we showed that SnRK2.6 (Sucrose Nonfermenting 1-Related Protein Kinase 2.6), a key regulator in ABA signaling, interacts with phyB and participates in light-induced stomatal opening. First, we checked the interaction between phyB and SnRK2s, and found that SnRK2.2/2.3/2.6 kinases physically interacted with phyB in yeast and in vitro. We also performed co-IP assay to support that SnRK2.6 interacts with phyB in plant. To investigate the role of SnRK2.6 in red light-induced stomatal opening, we obtained the snrk2.6 mutant and overexpression lines, and found that snrk2.6 mutant exhibited a significantly larger stomatal aperture under red light treatment, while the two independent overexpression lines showed significantly smaller stomatal aperture, indicative of a negative role for SnRK2.6 in red light-induced stomatal opening. The interaction of SnRK2.6 with red light receptor and the negative role of SnRK2.6 in red light-induced stomatal opening provide new evidence for the crosstalk between ABA and red light in guard cell signaling.

Salidroside (Sal) is a natural antioxidant that elicits cardioprotective and neuroprotective effects in vivo and in vitro; however, its impact on hepatic ischemia/reperfusion (I/R) injury remains unclear. The purpose of this study was to investigate the hepatoprotective effects of salidroside against segmental (70%) warm hepatic I/R injury in rats. Animals were randomized into Sham, Sham+salidroside pretreatment (Sal), Sham+Sal+carboxyatractyloside (CATR), Sham+CATR, I/R, I/R+Sal, I/R+Sal+CATR and I/R+CATR groups. The hepatic artery, left portal vein and median liver lobes were occluded for 60min and then unclamped to allow reperfusion. Pretreatment with salidroside (20mg/kg/day for 7 days, intraperitoneally) significantly decreased serum alanine aminotransferase (sALT) and serum aspartate aminotransferase (sAST) levels after 6h and 24h of reperfusion and protected the liver against I/R-induced injury. However, this protective effect could be reversed by CATR, a mitochondrial permeability transition pore (MPTP) opener (5mg/kg 30min before I/R insult, intraperitoneally). Mechanistic studies have revealed that salidroside inhibits glycogen synthase kinase-3 beta (GSK-3β) activity and enhances the NF-E2-related factor (Nrf2)-dependent antioxidant response by activating the Akt signaling pathway, thereby reducing mitochondrial reactive oxygen species generation, increasing MPTP resistance and preventing apoptosis by suppressing cytochrome c release and caspase activation during reperfusion. Therefore, salidroside ameliorates hepatocyte death and apoptosis through activation of the GSK-3β/Nrf2-dependent antioxidant response and subsequent MPTP inhibition. These results provide experimental evidence supporting the clinical use of salidroside for hepatoprotection in surgical settings.

When plants encounter environmental stresses, phytohormone abscisic acid (ABA) accumulates quickly and efficiently reduces water loss by inducing stomatal closure. Reactive oxygen species (ROS) is an important regulator in ABA-induced stomatal closure, and ROS generation is modulated by multiple components in guard-cell ABA signaling. ROP interactive CRIB-containing protein 7 (RIC7) has been found to negatively regulate ABA-induced stomatal closure. However, the molecular details of the RIC7 function in this process are unclear. Here, by using two RIC7 overexpressing mutants, we confirmed the negative role of RIC7 in ABA-induced stomatal closure and found that guard cells of RIC7 overexpressing mutants generated less H(2)O(2) than the wild type with ABA treatment, which were consistent with the reduced expression levels of ROS generation related NADPH oxidase genes AtRBOHD and AtRBOHF, and cytosolic polyamine oxidase genes PAO1 and PAO5 in the RIC7 overexpressing mutants. Furthermore, external applied H(2)O(2) failed to rescue the defects of stomatal closure in RIC7 overexpressing mutants. These results suggest that RIC7 affects H(2)O(2) generation in guard cells, and the function of H(2)O(2) is dependent on RIC7 in ABA-induced stomatal closure, indicative of interdependency between RIC7 and H(2)O(2) in ABA guard-cell signaling.

Propofol pretreatment before reperfusion, or propofol conditioning, has been shown to be cardioprotective, while its mechanism is unclear. The current study investigated the roles of endocannabinoid signaling in propofol cardioprotection in an in vivo model of myocardial ischemia/reperfusion (I/R) injury and in in vitro primary cardiomyocyte hypoxia/reoxygenation (H/R) injury. The results showed that propofol conditioning increased both serum and cell culture media concentrations of endocannabinoids including anandamide (AEA) and 2-arachidonoylglycerol (2-AG) detected by LC-MS/MS. The reductions of myocardial infarct size in vivo and cardiomyocyte apoptosis and death in vitro were accompanied with attenuations of oxidative injuries manifested as decreased reactive oxygen species (ROS), malonaldehyde (MDA), and MPO (myeloperoxidase) and increased superoxide dismutase (SOD) production. These effects were mimicked by either URB597, a selective endocannabinoids degradation inhibitor, or VDM11, a selective endocannabinoids reuptake inhibitor. In vivo study further validated that the cardioprotective and antioxidative effects of propofol were reversed by selective CB2 receptor antagonist AM630 but not CB1 receptor antagonist AM251. We concluded that enhancing endogenous endocannabinoid release and subsequent activation of CB2 receptor signaling represent a major mechanism whereby propofol conditioning confers antioxidative and cardioprotective effects against myocardial I/R injury.

In our previous study, osteopontin (OPN) was identified as one of the leading genes that promote the metastasis of hepatocellular carcinoma (HCC). However, the mechanism by which OPN promotes metastasis of HCC is not understood. In this study, RNA interference mediated by viral vectors-which could induce a long-lasting down-regulation in gene expression-was applied to analyze the role of OPN in metastasis of HCC. Three lentiviral vectors encoding microRNA against OPN, Lenti.OPNi-1, Lenti.OPNi-2, and Lenti.OPNi-3, were constructed and found to down-regulate the OPN level by 62%, 78%, and 95%, respectively, in HCCLM3 cells which had an overexpression of OPN and a higher metastatic potential. Consequently, both Lenti.OPNi-2 and Lenti.OPNi-3 induced a significant decrease in matrix metalloproteinase (MMP)-2 and urokinase plasminogen activator expression, and led to an obvious inhibition of both in vitro invasion and in vivo lung metastasis of HCCLM3 cells (P0.001). Moreover, Lenti.OPNi-3, rather than Lenti.OPNi-2, could also suppress in vitro proliferation and in vivo tumor growth of HCCLM3. Smaller detectable tumors were found in only 50% of mice after implantation of Lenti.OPNi-3-transfected HCCLM3 cells (341 +/- 502.6 mm(3) versus3500 mm(3) in controls; P0.001). Lenti.OPNi-3, not Lenti.OPNi-2, significantly suppressed the MEK/ERK1/2 pathway in HCCLM3 cells. Recombinant OPN was found to induce translocation of p65 into the nucleus of HCC cells and activation of MMP-2 and MEK/ERK/1/2, which were suppressed by the nuclear factor kappaB (NF-kappaB) inhibitor pyrrolidine dithiocarbamate.OPN plays an important role in metastasis as well as tumor growth of HCC, in which different minimum threshold levels of OPN are needed. These effects may occur through activation of the mitogen-activated protein kinase and NF-kappaB pathways, and MMP-2. OPN could be a hopeful target for the control of HCC.