[Mechanisms of bone formation by primary cilia].

Primary cilia are immotile cilia assembled from the centriole-derived basal body, and they protrude on the cell surface in almost all cell types during the cell cycle G0 phase. Due to the diffusion barrier at the ciliary base, cilia harbor selective G protein-coupled receptors, growth factor receptors, and ion channels on their membrane. Thus, cilia act as sensory organelles, regulating the proliferation and differentiation of the cells and promoting the formation and maturation of various organs including bone, brain, and kidney. It has been unveiled that malformation and dysregulation of cilia cause organ dysplasia, so-called ciliopathy, thus research on primary cilia has become active during the past 20 years. Research on the roles of cilia in bone formation and its regulatory mechanisms have also progressed. It is widely recognized that cilia of preosteoblasts receive hedgehog and promote differentiation of the cells to osteoblasts, resulting in the formation of skulls and long bones. Recently, it has been shown that a membrane-associated protein 4.1G is important in ciliogenesis, hedgehog signaling, and osteoblast differentiation in neonatal bone formation. In this review, we would like to summarize the roles of primary cilia in bone formation and their regulatory mechanisms including the contribution of 4.1G.

Extracellular Vesicles Derived from 3T3-L1 Adipocytes Enhance Procoagulant Activity.

Obesity is associated with the risk of venous thromboembolism. Thrombi are constantly formed via the coagulation cascade and degraded by the fibrinolytic system, so they tend to form in obese individuals. Adipocytes are involved in thrombus formation in obesity, but it is not clear whether bioactive factors from adipocytes directly initiate or enhance coagulation and thrombosis. In this study, we confirmed that adipocyte-derived extracellular vesicles (ADEVs) enhance procoagulant activity in vitro. ADEVs prepared from the culture supernatant of mature 3T3-L1 adipocytes shortened plasma clotting times. Moreover, the effect of ADEVs on clotting time was weakened when using plasma lacking factors of the extrinsic pathway, but not the intrinsic pathway. ADEVs contain tissue factors and phosphatidylserine, which are involved in the extrinsic pathway, and blockade of these molecules diminished the effects of ADEVs on plasma clotting time. Additionally, the effect of ADEVs on plasma clotting time was further enhanced when cells were stimulated with the proinflammatory cytokine tumor necrosis factor-α. Thus, ADEVs may be a factor in thrombus formation in obesity.

Elaidate, a trans fatty acid, suppresses insulin signaling for glucose uptake in a manner distinct from that of stearate.

The dietary intake of elaidate (elaidic acid), a trans-fatty acid, is associated with the development of various diseases. Since elaidate is a C18 unsaturated fatty acid with a steric structure similar to that of a C18 saturated fatty acid (stearate), we previously revealed that insulin-dependent glucose uptake was impaired in adipocytes exposed to elaidate prior to and during differentiation similar to stearate. However, it is still unknown whether the mechanism of impairment of insulin-dependent glucose uptake due to elaidate is similar to that of stearate. Here, we indicate that persistent exposure to elaidate has particular effects on insulin signaling and GLUT4 dynamics. Insulin-induced accumulation of Akt at the plasma membrane (PM) and elevations of phosphorylated Akt and AS160 levels in whole cells were suppressed in adipocytes persistently exposed to 50 µM elaidate. Interestingly, persistent exposure to the same concentration of stearate has no effect on the phosphorylated Akt and AS160 levels. When cells were exposed to these fatty acids, elaidate suppressed insulin-induced fusion, but not translocation, of GLUT4 storage vesicles in the PM, whereas stearate did not suppress the fusion and translocation of GLUT4 storage, indicating that elaidate has suppressive effects on the accumulation of Akt and fusion of GLUT4 storage vesicles and that both elaidate and stearate vary in the mechanisms by which they impair insulin-dependent glucose uptake.

Positions of Hydroxyl Groups in Chrysin are Critical for Inhibiting Plasminogen Activator Inhibitor-1 Release from Human Umbilical Vein Endothelial Cells.

Chrysin suppresses the TNFα-induced increase in the secretion of plasma plasminogen activator inhibitor 1 (PAl-1), a risk factor for thrombotic diseases, from human umbilical vein endothelial cells (HUVECs). The present study aimed to determine the association between the location of the hydroxyl groups in chrysin.to levels of-PAI-1. in the medium of HUVEC stimulated with TNFα. We cultured HUVEC for 3 h in medium containing chrysin or various flavonoids and then stimulated them with TNFα (10 ng/mL) for 12 h. Levels of PAI-1 antigen measured using ELISA showed that chrysin significantly inhibited the PAl- I increase with an IC50 of 15.6 µM. The flavones, galangin, baicalein, 5-hydroxyflavone, 6-hydroxyflavone, 7-hydroxyflavone and quercetin did not significantly inhibit the PAI- increase. Apigenin and luteolin were cytotoxic and thus their ability to inhibit PAI production could not be evaluated. Chrysin also inhibited PAI- mRNA expression whereas the other compounds did not. Hydroxyl groups located in the A-5 and A-7 positions were essential for the inhibitoryactivity, which along with cytotoxicity, was significantly influenced by adding a third hydroxyl group.

Acidic sialidase activity is aberrant in obese and diabetic mice.

Mammalian sialidases (NEU1, NEU2, NEU3 and NEU4) that remove sialic acids from glycoconjugates have been implicated in diverse cellular functions. Human sialidases are involved in the development of various disease states such as cancer, diabetes and arteriosclerosis. Unregulated acidic sialidase NEU1 activity is associated with the pathogenesis of lysosomal storage disorder (LSD) sialidosis, abnormal immune responses and cancer progression. Obesity is closely related to several chronic diseases such as diabetes, cardiovascular diseases, hyperlipidemia or hypertension that are associated with metabolic syndrome. We examined fluctuations in mRNA levels and sialidase activities of NEU1 in two strains of obese and diabetic mice to assess the involvement of NEU1 in obesity. The activity of NEU1 was preferentially higher in epididymal fat and lower in the livers of two strains of obese and diabetic mice. Fluctuations in NEU1 activity might be associated with the pathological status of these tissues in obesity.

Xanthoangelols isolated from Angelica keiskei inhibit inflammatory-induced plasminogen activator inhibitor 1 (PAI-1) production.

The folk medicine Angelica keiskei (Ashitaba) exhibits antitumor, antioxidant and antidiabetic activities and it has recently attracted attention as a health food. Ashitaba is thought to have antithrombotic properties, but this has not yet been scientifically proven. The elevation of plasma plasminogen activator inhibitor 1 (PAI-1), an inhibitor of fibrinolysis results in a predisposition to the risk of thrombosis. The present study showed that Ashitaba exudates injected intraperitoneally and orally administered over long-term suppressed the lipopolysaccharide (LPS) induced PAI-1 increase in mouse plasma. We also found that xanthoangelol, xanthoangelols B and D, the components of Ashitaba exudates, significantly inhibited TNFα-induced PAI-1 production from human umbilical vein endothelial cells (HUVECs). These findings suggest that Ashitaba can decrease elevated PAI-1 production, and that daily consumption of Ashitaba product might maintain anticoagulant status by inhibiting elevations in PAI-1 under inflammatory conditions.