Recent studies have demonstrated that the Wnt/β-catenin signaling plays an important role in stem cell aging. However, the mechanisms of cell senescence induced by Wnt/β-catenin signaling are still poorly understood. Our preliminary study has indicated that activated Wnt/β-catenin signaling can induce MSC aging. In this study, we reported that the Wnt/β-catenin signaling was a potent activator of reactive oxygen species (ROS) generation in MSCs. After scavenging ROS with N-acetylcysteine, Wnt/β-catenin signaling-induced MSC aging was significantly attenuated and the DNA damage and the expression of p16(INK4A), p53, and p21 were reduced in MSCs. These results indicated that the Wnt/β-catenin signaling could induce MSC aging through promoting the intracellular production of ROS, and ROS may be the main mediators of MSC aging induced by excessive activation of Wnt/β-catenin signaling.

Continuous turnover of intracellular components by autophagy is necessary to preserve cellular homeostasis in all tissues. Despite recent advances in identifying autophagy-related genes and understanding the functions of autophagy in developmental and pathological conditions, so far, the role of autophagy in platelet, a specific anucleate cell type, is poorly understood. In this study, we showed that human platelets express the autophagy-related proteins ATG5, ATG7, and LC3. The same as in nucleated mammalian cells, autophagy was stimulated by cell starvation or the MTOR inhibitor rapamycin in a phosphatidylinositol 3-kinase (PtdIns3K)-dependent manner. Disruption of autophagic flux led to impairment of platelet aggregation and adhesion. Furthermore, Becn1 heterozygous knockout mice displayed a prolonged bleeding time and reduced platelet aggregation. These results suggest a potential role of autophagy in the regulation of platelet function, and imply that gene transcription may not be an essential prerequisite for adaptive autophagy.

Pyruvate dehydrogenase kinase 1 (PDK1) is overexpressed in ovarian cancer and thus is a promising anticancer therapeutic target. Our previous work suggests that coumarin compounds are potential inhibitors of PDKs. In this study, we used the ovarian cancer cell line SKOV3 as the model system and examined whether dicumarol (DIC), a coumarin compound, could inhibit ovarian cancer through targeting PDK1. We showed that DIC potently inhibited the kinase activity of PDK1, shifted the glucose metabolism from aerobic glycolysis to oxidative phosphorylation, generated a higher level of reactive oxygen species (ROS), attenuated the mitochondrial membrane potential (MMP), induced apoptosis, and reduced cell viability in vitro. The same phenotypes induced by DIC also were translated in vivo, leading to significant suppression of xenograft growth. This study not only identifies a novel inhibitor for PDK1, but it also reveals novel anticancer mechanisms of DIC and provides a promising anticancer therapy that targets the Warburg effect.

Increasing evidences indicate that reactive oxygen species are the main factor promoting stem cell aging. Recent studies have demonstrated that coenzyme Q10 (CoQ10) plays a positive role in organ and cellular aging. However, the potential for CoQ10 to protect stem cell aging has not been fully evaluated, and the mechanisms of cell senescence inhibited by CoQ10 are still poorly understood. Our previous study had indicated that D-galactose (D-gal) can remarkably induce mesenchymal stem cell (MSC) aging through promoting intracellular ROS generation. In this study, we showed that CoQ10 could significantly inhibit MSC aging induced by D-gal. Moreover, in the CoQ10 group, the expression of p-Akt and p-mTOR was clearly reduced compared with that in the D-gal group. However, after Akt activating by CA-Akt plasmid, the senescence-cell number in the CoQ10 group was significantly higher than that in the control group. These results indicated that CoQ10 could inhibit D-gal-induced MSC aging through the Akt/mTOR signaling.

Key Points• MINK1 promotes hemostasis and thrombosis in vivo.• MINK1 specifically regulates platelet dense-granule secretion.The sterile-20 kinase misshapen/Nck-interacting kinase (NIK)-related kinase 1 (MINK1) is involved in many important cellular processes such as growth, cytoskeletal rearrangement, and motility. Here, with MINK1-deficient (MINK1 2/2 ) mice, we showed that MINK1 plays an important role in hemostasis and thrombosis via the regulation of platelet functions. In the tail-bleeding assay, MINK12/2 mice exhibited a longer bleeding time than wild-type (WT) mice (575.2 6 59.7 seconds vs 419.6 6 66.9 seconds). In a model of ferric chloride-induced mesenteric arteriolar thrombosis, vessel occlusion times were twice as long in MINK1 2/2 mice as in WT mice. In an in vitro microfluidic whole-blood perfusion assay, thrombus formation on a collagen matrix under arterial shear conditions was significantly reduced in MINK1 2/2 platelets. Moreover, MINK1 2/2 platelets demonstrated impaired aggregation and secretion in response to low doses of thrombin and collagen. Furthermore, platelet spreading on fibrinogen was largely hampered in MINK1 2/2 platelets. The functional differences of MINK1 2/2 platelets could be attributed to impaired adenosine 59-diphosphate secretion. Signaling events associated with MINK1 appeared to involve extracellular signal-regulated kinase, p38, and Akt. Hence, MINK1 may be an important signaling molecule that mediates mitogen-activated protein kinase signaling and participates in platelet activation and thrombus formation. (Blood. 2016;127(7):927-937)

BackgroundSelenoprotein S (SelS) is a transmembrane protein that is expressed in the liver, skeletal muscle, adipose tissue, pancreatic islets, kidney, and blood vessels. In addition to its transmembrane localization, SelS is also secreted from hepatoma HepG2 cells (but not L6 skeletal muscle cells, 3T3-L1 adipocytes, Min6 pancreatic β cells and human embryonic kidney 293 cells) and has been detected in the serum of some human subjects, with a detection rate of 31.1 %. These findings prove that serum SelS is secreted by hepatocytes. However, whether vascularly expressed SelS can be secreted has not been reported. Transmembrane SelS has been suggested to play different roles in the pathogenesis and progression of diabetes mellitus (DM) and atherosclerosis (AS), but the association of secreted SelS with DM and macroangiopathy remains unclear.Research design and methodsSupernatants were collected from human umbilical vein endothelial cells (HUVECs), human aortic vascular smooth muscle cells (HA/VSMCs) and human hepatoma HepG2 cells that were untransfected or transfected with the indicated plasmid and concentrated for western blotting. Serum samples were collected from 158 human subjects with or without type 2 DM (T2DM) and/or AS. Serum SelS levels were measured using an enzyme-linked immunosorbent assay.ResultsSecreted SelS was only detected in the supernatants of hepatoma HepG2 cells. The SelS detection rate among the 158 human serum samples was 100 %, and the average SelS level was 64.81 ng/dl. The serum SelS level in the isolated DM subjects was lower than the level in the healthy control subjects (52.66 ± 20.53 vs 70.40 ± 21.38 ng/dl). The serum SelS levels in the DM complicated with SAS subjects (67.73 ± 21.41 ng/dl) and AS subjects (71.69 ± 27.00 ng/dl) were significantly increased compared with the serum SelS level in the isolated DM subjects. There was a positive interaction effect between T2DM and AS on the serum SelS level (P = 0.002). Spearman correlation analysis showed that the serum SelS level was negatively correlated with fasting plasma glucose.ConclusionsVascular endothelial and vascular smooth muscle cells could not secrete SelS. Serum SelS was primarily secreted by hepatocytes. SelS was universally detected in human serum samples, and the serum SelS level was associated with T2DM and its macrovascular complications. Thus, regulating liver and serum SelS levels might become a new strategy for the prevention and treatment of DM and its macrovascular complications.Electronic supplementary materialThe online version of this article (doi:10.1186/s12933-016-0388-3) contains supplementary material, which is available to authorized users.

Pyruvate dehydrogenase kinases (PDKs) are key enzymes in glucose metabolism, negatively regulating pyruvate dehyrogenase complex (PDC) activity through phosphorylation. Inhibiting PDKs could upregulate PDC activity and drive cells into more aerobic metabolism. Therefore, PDKs are potential targets for metabolism related diseases, such as cancers and diabetes. In this study, a series of computer-aided virtual screening techniques were utilized to discover potential inhibitors of PDKs. Structure-based screening using Libdock was carried out following by ADME (adsorption, distribution, metabolism, excretion) and toxicity prediction. Molecular docking was used to analyze the binding mechanism between these compounds and PDKs. Molecular dynamic simulation was utilized to confirm the stability of potential compound binding. From the computational results, two novel natural coumarins compounds (ZINC12296427 and ZINC12389251) from the ZINC database were found binding to PDKs with favorable interaction energy and predicted to be non-toxic. Our study provide valuable information of PDK-coumarins binding mechanisms in PDK inhibitor-based drug discovery.

Interleukin-8 (IL-8, also named CXCL8) binds to its receptors (CXCR1 and CXCR2) with subsequent recruitment of neutrophils and enhancement of their infiltration into inflamed sites, which exaggerates inflammation in many diseases. Recent studies have proposed that metabolic disorders can be attenuated by counteracting certain inflammatory signal pathways. In this study, we examined whether intervention with G31P, an antagonist of CXCL8, could attenuate tissue inflammation and development of metabolic disorders in db/db mice. The db/m and db/db mice were subcutaneously injected with G31P or equivalent normal saline once a day for 6 wk. The physical and metabolic parameters, glucose tolerance, insulin sensitivity, hepatic lipid accumulation, and inflammation markers were measured. G31P improved hepatic insulin sensitivity by modulating expression of genes related to gluconeogenesis and phosphorylated Akt levels. The expressions of several genes encoding proteins involved in de novo lipogenesis were decreased in G31P-treated db/db mice. Meanwhile, immune cell infiltration and cytokine release were attenuated in db/db mice with G31P treatment. G31P also improved the ratio of proinflammatory M1 and anti-inflammatory M2 macrophages. Furthermore, G31P ameliorates metabolic disturbances via inhibition of CXCR1 and CXCR2 pathways in db/db mice. These data suggest that the selective inhibition of CXC chemokines may have therapeutic effects on symptoms associated with obesity and diabetes.