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[en] Highlights: • The expression level of ACC2 is up-regulated in the mutant of BPG2. • GUN1 and GUN5-mediated plastid signals play a role in the upregulation of ACC2 in the bpg2 mutant. • The level of ACC2 is markedly increased in a GUN-dependent manner under plastid gene expression inhibitor treatment. In Arabidopsis thaliana (Arabidopsis), Acetyl-CoA Carboxylase 2 (ACC2) is a nuclear DNA-encoded and plastid-targeted enzyme that catalyzes the conversion of acetyl-CoA to malonyl-CoA. ACC2 improves plant growth and development when chloroplast translation is impaired. However, little is known about the upstream signals that regulate ACC2. Here, through analyzing the transcriptome changes in brz-insensitive-pale green (bpg) 2-2, a pale-green mutant with impaired chloroplast gene expression resulting from loss of the BPG2 function, we found that the level of ACC2 was significantly up-regulated. Through performing genetic analysis, we further demonstrated that loss of the GENOMES UNCOUPLED 1 (GUN1) or GUN5 function partly perturbed the up-regulation of ACC2 in the bpg2-2 mutant, whereas ABA INSENSITIVE 4 (ABI4)-function-loss had no clear effect on the ACC2 expression. Furthermore, when plants were treated with plastid translation inhibitors, such as lincomycin and spectinomycin, the ACC2 transcriptional level was also markedly increased in a GUN-dependent manner. In conclusion, our results suggested that the GUN-involved plastid-to-nucleus retrograde communication played a role in regulating ACC2 in Arabidopsis.
[en] Gas-permeable polymeric membranes containing carboxyl groups which are suitable for enzyme immobilization were investigated in order to use them as gas electrode membranes in biosensors. Carboxylated polyurethane (CPU) was synthesized via a reaction between 2,2-bis(hydroxymethyl)propionic acid as a chain extender and prepolymers prepared from polycarprolactone (Mn=2,000) and 4,4'-diphenylmethane diisocynate. It was difficult to prepare membranes from the pure CPU because of its high elasticity and cohesion. However, transparent free-standing membranes were easily prepared from the blend solutions of CPU and carboxylated poly(vinyl chloride) (CPVC) in tetrahydrofuran. Both elasticity and cohesion of the CPU/CPVC membranes were decreased with increasing the content of CPVC. DSC experiment suggests that CPU and CPVC may be well mixed. Permeability coefficients for O2 and CO2 (PO2 and PCO2) in the membranes increased as the proportion of CPU increased. The addition of dioctyl phthalate (DOP), a plasticizer, significantly enhanced the PO2 and PCO2 which were 4.4 and 30 Barrer, respectively, in the CPU/CPVC (80/20 wt/wt) membranes containing 20% of DOP at 25 .deg. C and 100 psi. Thus this type of membranes may have a potential for the use as gas electrode membranes in biosensors
[en] Highlights: • α-LA reduces oxidative stress in diabetic mouse retinas. • α-LA increases p-AMPK, p-ACC, PPARδ, and SIRT3 in diabetic mouse retinas. • α-LA decreases OGT, TXNIP, and cleaved-PARP and -caspase-3 in diabetic mouse retinas. • α-LA decreases AMPK interaction with OGT, reducing retinal injuries in diabetic mice. Oxidative stress plays an important role in the development of diabetic retinopathy. Here, we examined whether α-lipoic acid (α-LA), a natural antioxidant, attenuated retinal injury in diabetic mice. The α-LA was orally administered to control mice or mice with streptozotocin-induced diabetes. We found that α-LA reduced oxidative stress, decreased and increased retinal 4-hydroxy-2-nonenal and glutathione peroxidase, respectively, and inhibited retinal cell death. Concomitantly, α-LA reversed the decreased activation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase, and increased the levels of peroxisome proliferator-activated receptor delta and sirtuin3 in diabetic mouse retinas, similar to results shown after metformin treatment of retinal pigment epithelial cells (RPE) exposed to high glucose. Moreover, α-LA lowered the levels of O-linked β-N-acetylglucosamine transferase (OGT) and thioredoxin-interacting protein (TXNIP) in diabetic retinas that were more pronounced after metformin treatment of RPE cells. Importantly, α-LA lowered interactions between AMPK and OGT as shown by co-immunoprecipitation analyses, and this was accompanied by less cell death as measured by double immunofluorescence staining by terminal deoxynucleotide transferase-mediated dUTP nick-end labelling and OGT or TXNIP in retinal ganglion cells. Consistently, α-LA lowered the levels of cleaved poly(ADP-ribose) polymerase and pro-apoptotic marker cleaved caspase-3 in diabetic retinas. Our results indicated that α-LA reduced retinal cell death partly through AMPK activation or OGT inhibition in diabetic mice.
[en] Highlights: • PF-06409577 protects retinal pigment epithelium (RPE) cells from ultra-violet radiation (UVR). • PF-06409577 activates AMPK signaling in RPE cells. • AMPK activation mediates PF-06409577-induced RPE cytoprotection against UVR. • PF-06409577 activates NADPH and Nrf2 signaling in RPE cells. • PF-06409577 inhibits UVR-induced oxidative injury in RPE cells. Ultra-violet (UV) radiation (UVR) to human retinas induces oxidative injury to the resident retinal pigment epithelium (RPE) cells. PF-06409577 a novel, potent and direct AMP-activated protein kinase (AMPK) activator. In ARPE-19 cells and primary murine RPE cells, PF-06409577 significantly inhibited UVR-induced viability reduction, cell death and apoptosis. PF-06409577 activated AMPK signaling in RPE cells by increasing AMPKα1-acetyl-CoA carboxylase phosphorylation and AMPK activity. AMPK inhibition, by AMPKα1-shRNA, -CRISPR/Cas9 knockout or -T172A dominant negative mutation, almost abolished PF-06409577-induced RPE cytoprotection against UVR. PF-06409577 enhanced nicotinamide adenine dinucleotide phosphate (NADPH) activity and expression levels of Nrf2-dependent genes in RPE cells. Furthermore, UVR-induced reactive oxygen species (ROS) production, lipid peroxidation and DNA damage were largely inhibited by the AMPK activator. In summary, PF-06409577 inhibits UVR-induced oxidative stress and RPE cell death by activating AMPK signaling.
[en] Lactococcus lactis, a gram-positive bacterium, encounters various environmental stresses, especially acid stress, during fermentation. Small RNAs (sRNAs) that serve as regulators at post-transcriptional level play important roles in acid stress response. Here, a novel sRNA S042 was identified by RNA-Seq, RT-PCR and Northern blot. The transcription level of s042 was upregulated 2.29-fold under acid stress by Quantitative RT-PCR (qRT-PCR) analysis. Acid tolerance assay showed that overexpressing s042 increased the survival rate of L. lactis F44 and deleting s042 significantly inhibited the viability under acidic conditions. Moreover, the targets were predicted by online software and four genes were chosen as candidates. Among them, argR (arginine regulator) and accD (acetyl-CoA carboxylase carboxyl transferase subunit beta) were validated to be the direct targets activated by S042 through reporter fusion assay. The regulatory mechanism between S042 and its targets was further investigated through Bioinformatics and qRT-PCR. This study served to highlight the role of the novel sRNA S042 in acid resistance of L. lactis and provided new insights into the response mechanism of acid stress.
[en] Highlights: • Podocyte-specific ACCβ overexpression causes severe podocyte injury in diabetic mice. • Podocyte-specific ACCβ overexpression increased proteinuria in diabetic mice. • AMPK activation ameliorates ACCβ overexpression-related podocyte injury. • Inhibition of ACCβ activity may serve as a therapy for diabetic nephropathy. A single nucleotide polymorphism (SNP) within the acetyl CoA carboxylase (ACC) β gene (ACACB), rs2268388, has been shown to be associated with susceptibility to development of proteinuria in patients with type 2 diabetes. To investigate the biological roles of ACCβ in the pathogenesis of diabetic nephropathy, we examined the effects of overexpression of ACACB using podocyte-specific ACACB-transgenic mice or ACACB-overexpressing murine podocytes. Podocyte-specific ACACB-transgenic mice or littermate mice were treated with streptozotocin (STZ) to induce diabetes, and 12 weeks after induction of diabetes, we examined the expression of podocyte markers to evaluate the degree of podocyte injury in these mice. We also examined the effects of ACCβ on podocyte injury in ACACB- or LacZ-overexpressing murine podocytes. Podocyte-specific ACACB overexpression did not cause visible podocyte injury in non-diabetic mice. In STZ-induced diabetic mice, ACACB-transgenic mice showed a significant increase in urinary albumin excretion, accompanied by decreased synaptopodin expression and podocin mislocalization in podocytes, compared with wild-type mice. In cultured murine podocytes, overexpression of ACACB significantly decreased synaptopodin expression and reorganized stress fibers under high glucose conditions, but not in normal glucose conditions. The decrease of synaptopodin expression and reorganized stress fibers observed in ACACB overexpressing cells cultured under high glucose conditions was reversed by a treatment of 5-aminoimidazole-4-carboxamide-1-beta-4-ribofuranoside (AICAR), activator of AMP-activated protein kinase (AMPK). The excess of ACCβ might contribute to exacerbation of podocyte injury in the kidney of an animal model for diabetes mellitus, and the AMPK/ACCβ pathway may be a novel therapeutic target for the prevention of diabetes-related podocyte injury.
[en] New liquid-crystalline biphenyl carboxylates with an achiral swallow-tail derived from 1,3-dialkoxy-2- propanol [(ROCH2)2CHOH] where R is methyl, ethyl, propyl, butyl, CH2CF3, and CH2CF2CF3 were prepared. These achiral liquid crystals having 1,3-dialkoxy-2-propyl moieties exhibit diverse phase sequences [I-SmA- (SmC)-(SmCalt)-Cr] depending on the substituent R group of the swallow-tail. The compounds carrying a fluorinated swallow-tail exhibit antiferroelectric-like smectic C phases, and their temperature ranges are broader than the corresponding non-fluorinated swallow-tailed ones
[en] In natural medium, it has been comparatively studied the activities of the enzymes of carboanhydrase (CA, CF 184.108.40.206), phosphoenolpyruvate carboxylase (PEPC, CF 220.127.116.11) and ribulose 1.5-bisphosphate carboxylase (RBPC, CF 18.104.22.168) in the leaves during active growth of ontogenesis of plants of ordinary bean (Phaseolus vulgaris L.), eggplant (Solanum melongena L.), cucumber (Cucumis sativus L.) and tomato (Solanum lycopersicum L.), of which seeds irradiated at 1, 5, 10, 50, 100, 200, 300 and 400 Gy doses (irradiation rate was p=0.19 Gy/sec). It has been established that CA and RBPC enzymes in the studied plants exhibit similar activity under radiation exposure. The enzyme PEPC has a low catalytic activity due to the photosynthesis mechanism of the plants.