Sirtuin 1 activator alleviated lethal inflammatory injury via promotion of autophagic degradation of pyruvate kinase M2.

Upregulation of pyruvate kinase M2 (PKM2) is critical for the orchestration of metabolism and inflammation in critical illness, while autophagic degradation is a recently revealed mechanism that counter-regulates PKM2. Accumulating evidence suggests that sirtuin 1 (SIRT1) function as a crucial regulator in autophagy. The present study investigated whether SIRT1 activator would downregulate PKM2 in lethal endotoxemia via promotion of its autophagic degradation. The results indicated that lethal dose of lipopolysaccharide (LPS) exposure decreased the level of SIRT1. Treatment with SRT2104, a SIRT1 activator, reversed LPS-induced downregulation of LC3B-II and upregulation of p62, which was associated with reduced level of PKM2. Activation of autophagy by rapamycin also resulted in reduction of PKM2. The decline of PKM2 in SRT2104-treated mice was accompanied with compromised inflammatory response, alleviated lung injury, suppressed elevation of blood urea nitrogen (BUN) and brain natriuretic peptide (BNP), and improved survival of the experimental animals. In addition, co-administration of 3-methyladenine, an autophagy inhibitor, or Bafilomycin A1, a lysosome inhibitor, abolished the suppressive effects of SRT2104 on PKM2 abundance, inflammatory response and multiple organ injury. Therefore, promotion of autophagic degradation of PKM2 might be a novel mechanism underlying the anti-inflammatory benefits of SIRT1 activator.

REV-ERBα Agonist GSK4112 attenuates Fas-induced Acute Hepatic Damage in Mice.

Fas-induced apoptosis is a central mechanism of hepatocyte damage during acute and chronic hepatic disorders. Increasing evidence suggests that circadian clock plays critical roles in the regulation of cell fates. In the present study, the potential significance of REV-ERBα, a core ingredient of circadian clock, in Fas-induced acute liver injury has been investigated. The anti-Fas antibody Jo2 was injected intraperitoneally in mice to induce acute liver injury and the REV-ERBα agonist GSK4112 was administered. The results indicated that treatment of GSK4112 decreased the level of plasma ALT and AST, attenuated the liver histological changes, and promoted the survival rate in Jo2-insulted mice. Treatment with GSK4112 also downregulated the activities of caspase-3 and caspase-8, suppressed hepatocyte apoptosis. In addition, treatment with GSK4112 decreased the level of Fas and enhanced the phosphorylation of Akt. In conclusion, treatment with GSK4112 alleviated Fas-induced apoptotic liver damage in mice, suggesting that REV-ERBα agonist might have potential value in pharmacological intervention of Fas-associated liver injury.

A disposable and sensitive non-enzymatic glucose sensor based on 3D graphene/Cu2O modified carbon paper electrode.

Herein, a three-dimensional graphene wall (GWs) and nano-Cu2O modified carbon fiber paper (CFP) electrode were used to develop a disposable and sensitive non-enzymatic glucose sensor. This sensing interface of GWs/Cu2O consists of an interlaced CFP on which intercrossed graphene walls (GWs) were vertically tethered in situ by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD), and Cu2O nanoparticles (NPs) were evenly grew on the 3D GWs layer and skeleton through the complete thermal decomposition of copper acetate (Cu (CH3COO)2) at high temperature. The CFP/GWs/Cu2O shows a large specific surface area and rich solution diffusion channels, which can expose more catalytic active sites without Nafion fixation film, thus greatly improving the electrocatalytic performance of this glucose sensor. The CFP/GWs/Cu2O sensor shows excellent catalytic performance to glucose with a linear detection range of 0.5 µM-5166 µM, LOD of 0.21 µM, and response time <4 s. This kind of disposable and sensitive electrode can capable of controlling uniform growth and accurate quantification, and has great development potential in the field of medical detection and the commercialization of wearable sensors.

Diversity in mitochondrial function explains differences in vascular oxygen sensing.

Renal arteries (RAs) dilate in response to hypoxia, whereas the pulmonary arteries (PAs) constrict. In the PA, O2 tension is detected by an unidentified redox sensor, which controls K+ channel function and thus smooth muscle cell (SMC) membrane potential and cytosolic calcium. Mitochondria are important regulators of cellular redox status and are candidate vascular O2 sensors. Mitochondria-derived activated oxygen species (AOS), like H2O2, can diffuse to the cytoplasm and cause vasodilatation by activating sarcolemmal K+ channels. We hypothesize that mitochondrial diversity between vascular beds explains the opposing responses to hypoxia in PAs versus RAs. The effects of hypoxia and proximal electron transport chain (pETC) inhibitors (rotenone and antimycin A) were compared in rat isolated arteries, vascular SMCs, and perfused organs. Hypoxia and pETC inhibitors decrease production of AOS and outward K+ current and constrict PAs while increasing AOS production and outward K+ current and dilating RAs. At baseline, lung mitochondria have lower respiratory rates and higher rates of AOS and H2O2 production. Similarly, production of AOS and H2O2 is greater in PA versus RA rings. SMC mitochondrial membrane potential is more depolarized in PAs versus RAs. These differences relate in part to the lower expression of proximal ETC components and greater expression of mitochondrial manganese superoxide dismutase in PAs versus RAs. Differential regulation of a tonically produced, mitochondria-derived, vasodilating factor, possibly H2O2, can explain the opposing effects of hypoxia on the PAs versus RAs. We conclude that the PA and RA have different mitochondria.