Cbl-b regulates macrophage activation

Aging and overnutrition cause obesity in rodents and humans. It is well-known that obesity causes various diseases by producing insulin resistance (IR). Macrophages infiltrate the adipose tissue (AT) of obese individuals and cause chronic low-level inflammation associated with IR. Macrophage infiltration is regulated by the chemokines that are released from hypertrophied adipocytes and the immune cells in AT. Saturated fatty acids are recognized by toll-like receptor 4 (TLR4) and induce inflammatory responses in AT macrophages (ATMs). The inflammatory cytokines that are released from activated ATMs promote IR in peripheral organs, such as the liver, skeletal muscle and AT. Therefore, ATM activation is a therapeutic target for IR in obesity. The ubiquitin ligase Casitas b-lineage lymphoma-b (Cbl-b) appears to potently suppress macrophage migration and activation. Cbl-b is highly expressed in leukocytes and negatively regulates signals associated with migration and activation. Cbl-b deficiency enhances ATM accumulation and IR in aging- and diet-induced obese mice. Cbl-b inhibits migration-related signals and SFA-induced TLR4 signaling in ATMs. Thus, targeting Cbl-b may be a potential therapeutic strategy to reduce the IR induced by ATM activation. In this review, we summarize the regulatory functions of Cbl-b in ATMs

トクシマ ダイガク エイヨウ ガッカ ハツ ウチュウ ジッケン ノ アユミ ト コレカラ

Yuri Gagarin said,“The Earth is blue”, in the first manned spacecraft Vostok 1 in April 1961 when he glimpsed the planet from the space. Since then, human beings have been evolving technology of rocket, so that they can stay in space for several months and years. In Japan, JAXA has almost finished constructing“Kibo”, a space experimental module in the International Space Station（ISS）, in August, 2008. The first space research of Japan will be carried out at“Kibo”soon.We are also planning to perform a space experiment in“Kibo”to clarify the molecular mechanism of muscle atrophy caused by micro gravity. In this paper, we report our history and future plan to develop space research

Subcutaneous injection, from birth, of epigallocatechin-3-gallate, a component of green tea, limits the onset of muscular dystrophy in mdx mice: a quantitative histological, immunohistochemical and electrophysiological study

Dystrophic muscles suffer from enhanced oxidative stress. We have investigated whether administration of an antioxidant, epigallocatechin-3-gallate (EGCG), a component of green tea, reduces their oxidative stress and pathophysiology in mdx mice, a mild phenotype model of human Duchenne-type muscular dystrophy. EGCG (5mg/kg body weight in saline) was injected subcutaneously 4× a week into the backs of C57 normal and dystrophin-deficient mdx mice for 8weeks after birth. Saline was injected into normal and mdx controls. EGCG had almost no observable effects on normal mice or on the body weights of mdx mice. In contrast, it produced the following improvements in the blood chemistry, muscle histology, and electrophysiology of the treated mdx mice. First, the activities of serum creatine kinase were reduced to normal levels. Second, the numbers of fluorescent lipofuscin granules per unit volume of soleus and diaphragm muscles were significantly decreased by about 50% compared to the numbers in the corresponding saline-treated controls. Third, in sections of diaphragm and soleus muscles, the relative area occupied by histologically normal muscle fibres increased significantly 1.5- to 2-fold whereas the relative areas of connective tissue and necrotic muscle fibres were substantially reduced. Fourth, the times for the maximum tetanic force of soleus muscles to fall by a half increased to almost normal values. Fifth, the amount of utrophin in diaphragm muscles increased significantly by 17%, partially compensating for the lack of dystrophin expressio

Effects of single administration of Rokumi-gan (TJ-87) on serum amino acid concentration of 6 healthy Japanese male volunteers

Rokumi-gan (TJ-87) has beneficial effects on renal diseases, including pollakisuria, dysuria and edema. We previously reported that its long-term administration clinically improved serum protein concentration and edema in renal failure. In this study, we focused on amino acid/protein contents in Rokumi-gan as one of its effectors. Commercially prepared Rokumi-gan contained arginine, aspartate and glutamate at the high levels, alanine, phenylalanine and serine at the moderate levels, and glycine, histidine, isoleucine, leucine, lysine and valine at the low levels. To examine effects of Rokumi-gan on serum amino acid concentrations, 6 healthy Japanese volunteers were treated with commercially prepared Rokumi-gan, an amino acid mixture, and lactose. In subjects treated with an amino acid mixture containing similar amounts of amino acids in Rokumi-gan (10 g), or lactose, serum amounts of many amino acids, except for arginine, gradually and significantly decreased until 6 hr after their treatments. In contrast, a single treatment with Rokumi-gan (10 g) increased serum levels of several amino acids, alanine, arginine, glutamate, glycine and serine. Serum concentrations of almost of all tested amino acids showed the peak value 1-2 hr after administration, and they were sustained at the basal level even 6 hr after the treatment. Our present results suggest that Rokumi-gan may be a beneficial amino acid supplier, because it could sustain serum amino acid concentration at the higher level than an amino acid mixture supplement

ムジュウリョク ニヨル キンイシュク ト ソノ ショクジ ニヨル ヨボウ

The elucidate the mechanisms of microgravity-induced muscle atrophy, we focused on fast-type myosin heavy chain (MHC) degradation and expression of proteases in atrophied gastrocnemius muscles of neonatal rats exposed to 16-d spaceflight (STS-90). The spaceflight stimulated ubiquitination of proteins, including a MHC molecule, and accumulation of MHC degradation fragments in the muscles. Semi-quantitative RT-PCR revealed that the spaceflight significantly increased mRNA levels of cathepsin L, proteasome components, polyubiquitin, and ubiquitin-conjugating enzyme in the muscles, compared with those of ground control rats. The levels of μ-calpain, m-calpain, cathepsin B, and cathepsin H mRNAs were not changed by the spaceflight. We also found that tail-suspension of rats for 10 d or longer caused the ubiquitination and degradation of MHC in gastrocnemius muscle, as was observed in the spaceflight rats. In the muscle of suspended rats, these changes were closely associated with activation of proteasome and up-regulation of expression of mRNA for the proteasome components and polyubiquitin. Administration of a cysteine protease inhibitor, E-64, to the suspended rats did not prevent the MHC degradation. Our results suggest that spaceflight induces the degradation of muscle contractile proteins, including MHC, possibly through a ubiquitin-dependent proteolytic pathway. To elucidate whether the ubiquitination was accompanied with oxidative stress, we measured markers for oxidative stress, such as thiobarbituric acid-reactive substance (TBARS) and glutathione disulfide (GSSG), in gastrocnemius muscle of tail-suspended rats. Glutathione (GSH) concentration in the muscle significantly decreased from Day 5 and reached a minimum value on Day 10. Tail-suspension reciprocally increased concentrations of TBARS and GSSG in parallel with enhancement of protein ubiquitination, suggesting that oxidative stress may play an important role in protein ubiquitination caused by tail-suspension. To prevent ubiquitination associated with oxidative stress, we also administered an antioxidative nutrient, cysteine, to tail-suspended rats. Intragastric supplementation of 140 mg/rat of cysteine for 2 wks or longer normalized the ratio of GSH to GSSG in the muscle and suppressed protein ubiquitination and MHC fragmentation, compared with supplementation of the equimolar amount of alanine. The cysteine supplementation significantly suppressed the loss of hindlimb muscle weight. Our results also suggest that supplementation of antioxidative nutrients, such as cysteine, may be beneficial to prevent ubiquitination of muscle protein caused by unweighting

Astaxanthin Exerts Immunomodulatory Effect by Regulating SDH-HIF-1α Axis and Reprogramming Mitochondrial Metabolism in LPS-Stimulated RAW264.7 Cells

Astaxanthin (AX) is a carotenoid that exerts potent antioxidant activity and acts in cell membranes and mitochondria, which consist of the bilayer molecules. Targeting mitochondria to ameliorate inflammatory diseases by regulating mitochondrial metabolism has become possible and topical. Although AX has been shown to have anti-inflammatory effects in various cells, the mechanisms are quite different. In particular, the role of AX on mitochondrial metabolism in macrophages is still unknown. In this study, we investigated the effect of AX on mitochondria-mediated inflammation and its mechanisms in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. AX attenuated the mitochondrial O2− production and maintained the mitochondrial membrane potential, implying that AX preserved mitochondrial homeostasis to avoid LPS stimulation-induced mitochondrial dysfunction. Additionally, AX prevented the decrease in mitochondrial complexes I, II, and III, which were caused by LPS stimulation. Especially, AX inhibited the reduction in mitochondrial succinate dehydrogenase (SDH; complex II) activity and upregulated the protein and mRNA level of SDH complex, subunit B. Furthermore, AX blocked the IL-1β expression by regulating the SDH-HIF-1α axis and suppressed the energy shift from an OXPHOS phenotype to a glycolysis phenotype. These findings revealed important effects of AX on mitochondrial enzymes as well as on mitochondrial energy metabolism in the immune response. In addition, these raised the possibility that AX plays an important role in other diseases caused by SDH mutation and metabolic disorders

Ultra-high-purity iron is a novel and very compatible biomaterial

Metals and alloys are used widely in bone prosthetic materials, stents and dental tissue reconstructions. The most common materials are stainless steels and cobalt-chromium-nickel and titanium alloys. These alloys can be easily deformed but are hard to break. However, their affinity for cells and tissues is very low. In addition, they can sometimes provoke unexpected metal allergies. Iron is an abundant trace element essential for humans. However, excess amounts in particular of Fe2+ ions are toxic. We previously succeeded in obtaining 99.9996% ultra-high-purity iron (ABIKO iron). The chemical properties of ABIKO iron are completely different from that of conventional pure iron. For example, the reaction rate in hydrochloric acid is very slow and there is barely any corrosion. Here, we found that, in the absence of any type of coating, mammalian cells could easily attach to, and normally proliferate and differentiate on, ABIKO iron. On the other hand, cell densities and proliferation rate of the surfaces of plates made from Co–Cr–Mo or Ti–6Al–4V were significantly reduced. In addition, several stress and iron response genes, HSP70, SOD1, ATM and IRP2 did not change in the cells on ABIKO iron, while these genes were induced with exogenous application of FeSO4. Cells also secreted and fastened some organics on ABIKO iron. In vitro collagen binding assay showed that ABIKO iron binds higher amount of collagens. These findings highlight ABIKO iron as a novel biocompatible prosthetic material

C2C12筋管細胞においてモリンはデキサメタゾン誘導性の酸化ストレスと筋萎縮を抑制する

Glucocorticoids are the drugs most commonly used to manage inflammatory diseases. However, they are prone to inducing muscle atrophy by increasing muscle proteolysis and decreasing protein synthesis. Various studies have demonstrated that antioxidants can mitigate glucocorticoid-induced skeletal muscle atrophy. Here, we investigated the effect of a potent antioxidative natural flavonoid, morin, on the muscle atrophy and oxidative stress induced by dexamethasone (Dex) using mouse C2C12 skeletal myotubes. Dex (10 μM) enhanced the production of reactive oxygen species (ROS) in C2C12 myotubes via glucocorticoid receptor. Moreover, Dex administration reduced the diameter and expression levels of the myosin heavy chain protein in C2C12 myotubes, together with the upregulation of muscle atrophy-associated ubiquitin ligases, such as muscle atrophy F-box protein 1/atrogin-1, muscle ring finger protein-1, and casitas B-lineage lymphoma proto-oncogene-b. Dex also significantly decreased phosphorylated Foxo3a and increased total Foxo3a expression. Interestingly, Dex-induced ROS accumulation and Foxo3a expression were inhibited by morin (10 μM) pretreatment. Morin also prevented the Dex-induced reduction of myotube thickness, together with muscle protein degradation and suppression of the upregulation of atrophy-associated ubiquitin ligases. In conclusion, our results suggest that morin effectively prevents glucocorticoid-induced muscle atrophy by reducing oxidative stress

Balenine, Imidazole Dipeptide Promotes Skeletal Muscle Regeneration by Regulating Phagocytosis Properties of Immune Cells

Balenine is one of the endogenous imidazole dipeptides derived from marine products. It is composed of beta-alanine and 3-methyl-L-histidine, which exist mainly in the muscles of marine organisms. The physiological functions of dietary balenine are not well-known. In this study, we investigated whether the supplementation of dietary balenine was associated with muscle function in a cardiotoxin-indued muscle degeneration/regeneration model. Through morphological observation, we found that the supplementation of balenine-enriched extract promoted the regeneration stage. In addition, the expression of regeneration-related myogenic marker genes, such as paired box protein 7, MyoD1, myogenin, and Myh3, in a group of mice fed a balenine-enriched extract diet was higher than that in a group fed a normal diet. Moreover, the supplementation of balenine-enriched extract promoted the expression of anti-inflammatory cytokines as well as pro-inflammatory cytokines at the degeneration stage. Interestingly, phagocytic activity in the balenine group was significantly higherthan that in the control group in vitro. These results suggest that balenine may promote the progress of muscle regeneration by increasing the phagocytic activity of macrophages

Cbl-b ケッソン ニ ヨル マクロファージ ノ カッセイカ オ カイシタ タイトウノウ イジョウ

Obesity is a major cause of insulin resistance and is considered a chronic low-grade inflammatory disease. Substantial evidence has accumulated in recent years that chronic infiltration and activation of macrophages in white adipose tissue underlie the obesity-related component of these insulin resistant states. In the present study, we examined the role of Cbl-b, ubiquitin ligase, in insulin action. Elderly Cbl-b-deficient mice（Cbl-b－/－mice）developed glucose intolerance and peripheral insulin resistance. Deficiency of Cbl-b gene was associated with infiltration of macrophages into the WAT and expression of cytokines, such as tumor necrosis factor-α, interleukin-6 and monocyte chemoattractant protein-1. Furthermore, Vav1, a key factor in macrophage activation, was highly phosphorylated in peritoneal Cbl-b－/－macrophages, compared with wild type macrophages, suggesting that Cbl-b deficiency induces macrophage activation. Our results suggest that Cbl-b is a negative regulator of macrophage activation, and that macrophage activation by Cbl-b deficiency, at least in part, contributes to the peripheral insulin resistance and glucose intolerance