Oral intake of rice overexpressing ubiquitin ligase inhibitory pentapeptide prevents atrophy in denervated skeletal muscle

We previously reported that intramuscular injections of ubiquitin ligase CBLB inhibitory pentapeptide (Cblin; Asp-Gly-pTyr-Met-Pro) restored lost muscle mass caused by sciatic denervation. Here, we detected Cblin on the basolateral side of Caco-2 cells after being placed on the apical side, and found that cytochalasin D, a tight junction opener, enhanced Cblin transport. Orally administered Cblin was found in rat plasma, indicating that intact Cblin was absorbed in vitro and in vivo. Furthermore, transgenic Cblin peptide-enriched rice (CbR) prevented the denervation-induced loss of muscle mass and the upregulation of muscle atrophy-related ubiquitin ligases in mice. These findings indicated that CbR could serve as an alternative treatment for muscle atrophy.

Morin attenuates dexamethasone-mediated oxidative stress and atrophy in mouse C2C12 skeletal myotubes

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.

Crystal structure of inhibitor-bound human MSPL that can activate high pathogenic avian influenza

The structure of extracellular domain of MSPL and inhibitor complex helps to understand the TTSP functions, including TMPRSS2, and provides the insights of the infection of influenza and SARS-CoV.

Infection of certain influenza viruses is triggered when its HA is cleaved by host cell proteases such as proprotein convertases and type II transmembrane serine proteases (TTSP). HA with a monobasic motif is cleaved by trypsin-like proteases, including TMPRSS2 and HAT, whereas the multibasic motif found in high pathogenicity avian influenza HA is cleaved by furin, PC5/6, or MSPL. MSPL belongs to the TMPRSS family and preferentially cleaves [R/K]-K-K-R↓ sequences. Here, we solved the crystal structure of the extracellular region of human MSPL in complex with an irreversible substrate-analog inhibitor. The structure revealed three domains clustered around the C-terminal α-helix of the SPD. The inhibitor structure and its putative model show that the P1-Arg inserts into the S1 pocket, whereas the P2-Lys and P4-Arg interacts with the Asp/Glu-rich 99-loop that is unique to MSPL. Based on the structure of MSPL, we also constructed a homology model of TMPRSS2, which is essential for the activation of the SARS-CoV-2 spike protein and infection. The model may provide the structural insight for the drug development for COVID-19.

Comparison of cerebral cortex activation induced by tactile stimulation between natural teeth and implants

Background

The purpose of this study was to assess the cortical-level sensory differences between natural teeth with a periodontal membrane and dental implants.

Material and Methods

We used functional near-infrared spectroscopy (fNIRS) to measure brain activity in the cerebral cortex of 12 patients who had both natural teeth and dental implants in the lower molar region. Painless vibratory tactile stimulation was performed on both the natural teeth and the dental implants.

Results

Activation was seen in the somatosensory cortex during stimulation of both natural teeth and dental implants. A comparison of cortical activation showed no significant differences between natural teeth and dental implants.

Conclusions

These results indicate the possible existence of sensory input to the cerebral cortex via dental implants as well as natural teeth, and thus suggest that may not only the periodontal membrane be involved in the signaling pathway. The data from this experiment may help us for understanding the neural mechanisms underlying natural teeth and dental implants.

Key words:fNIRS, natural teeth, implants, brain activity, somatosensory cortex.

Longitudinal Findings of MRI and PET in West Syndrome with Subtle Focal Cortical Dysplasia

BACKGROUND AND PURPOSE

Despite the development of neuroimaging, identification of focal cortical dysplasia remains challenging. The purpose of this study was to show the longitudinal changes of MR imaging and FDG-PET in patients with West syndrome and subtle focal cortical dysplasia.

MATERIALS AND METHODS

Among 52 consecutive patients with West syndrome, 4 were diagnosed with subtle focal cortical dysplasia on 3T MR imaging. MR imaging and PET findings were evaluated longitudinally at onset and at 12 and 24 months of age.

RESULTS

At the onset of West syndrome, MR imaging demonstrated focal signal abnormalities of the subcortical white matter in 2 patients. In the other 2 patients, focal subcortical high-intensity signals became visible on follow-up T2WI as myelination progressed. PET at onset showed focal cortical hypometabolism in 3 patients, with 1 of these patients also having focal hypermetabolism and 1 having normal findings. On PET at 24 months, hypometabolism persisted in 2 patients and disappeared in 1, and hypermetabolism disappeared in 1. In 1 patient with normal MR imaging and PET findings at onset, focal hyperintensity and hypometabolism first appeared at 24 months of age. The findings on MR imaging and PET in these patients evolved differently with brain maturation and the clinical course.

CONCLUSIONS

Subtle focal cortical dysplasia can be undetectable on MR imaging at the onset of West syndrome and is not always accompanied by hypometabolism or hypermetabolism on PET. Longitudinal MR imaging and PET studies may be useful for detecting such lesions. Even in West syndrome with a congenital structural abnormality, PET findings evolve differently with brain maturation and the clinical condition.

Antiangiogenic agent sunitinib induces epithelial to mesenchymal transition and accelerates motility of colorectal cancer cells

Although vascular endothelial growth factor receptor (VEGF-R)-targeted antiangiogenic agents are important treatment for a number of human malignancies, there is accumulating evidence that the therapies may promote disease progression, such as invasion and metastasis. How tumors become to promote their evasiveness remains fully uncertain. One of possible mechanisms for the adaptation may be a direct effect of VEGF-R inhibitors on tumor cells expressing VEGF-R. To elucidate a direct effect of VEGF-R-targeting drug (sunitinib), we established a human colorectal cancer cell model adapted to sunitinib. The sunitinib-conditioned cells showed a significant increase in cellular motility and migration activities, compared to the vehicle-treated control cells. Consistent with the phenotype, the sunitinib-conditioned cells decreased the expression levels of E-cadherin (an epithelial marker), while significantly increased the levels of Slug and Zeb1 (mesenchymal markers). Expression profiles of VEGF-R in the sunitinib-conditioned cells showed that only neuropilin-1 (NRP1) expression was significantly increased among all VEGF-R tested. Blockade of NRP1 using its antagonist clearly repressed the migration activation in sunitinib-conditioned cells, but not in the control cells. These results suggest that inhibition of VEGF-R on colorectal cancer cells can drive the epithelial-mesenchymal transition, leading to activation of cell motility in an NRP1-dependent manner. J. Med. Invest. 64: 250-254, August, 2017.

Reactive oxygen species upregulate expression of muscle atrophy-associated ubiquitin ligase Cbl-b in rat L6 skeletal muscle cells

Unloading-mediated muscle atrophy is associated with increased reactive oxygen species (ROS) production. We previously demonstrated that elevated ubiquitin ligase casitas B-lineage lymphoma-b (Cbl-b) resulted in the loss of muscle volume (Nakao R, Hirasaka K, Goto J, Ishidoh K, Yamada C, Ohno A, Okumura Y, Nonaka I, Yasutomo K, Baldwin KM, Kominami E, Higashibata A, Nagano K, Tanaka K, Yasui N, Mills EM, Takeda S, Nikawa T. Mol Cell Biol 29: 4798–4811, 2009). However, the pathological role of ROS production associated with unloading-mediated muscle atrophy still remains unknown. Here, we showed that the ROS-mediated signal transduction caused by microgravity or its simulation contributes to Cbl-b expression. In L6 myotubes, the assessment of redox status revealed that oxidized glutathione was increased under microgravity conditions, and simulated microgravity caused a burst of ROS, implicating ROS as a critical upstream mediator linking to downstream atrophic signaling. ROS generation activated the ERK1/2 early-growth response protein (Egr)1/2-Cbl-b signaling pathway, an established contributing pathway to muscle volume loss. Interestingly, antioxidant treatments such as N-acetylcysteine and TEMPOL, but not catalase, blocked the clinorotation-mediated activation of ERK1/2. The increased ROS induced transcriptional activity of Egr1 and/or Egr2 to stimulate Cbl-b expression through the ERK1/2 pathway in L6 myoblasts, since treatment with Egr1/2 siRNA and an ERK1/2 inhibitor significantly suppressed clinorotation-induced Cbl-b and Egr expression, respectively. Promoter and gel mobility shift assays revealed that Cbl-b was upregulated via an Egr consensus oxidative responsive element at −110 to −60 bp of the Cbl-b promoter. Together, this indicates that under microgravity conditions, elevated ROS may be a crucial mechanotransducer in skeletal muscle cells, regulating muscle mass through Cbl-b expression activated by the ERK-Egr signaling pathway.

VEGF pathway-targeting drugs induce evasive adaptation by activation of neuropilin-1/cMet in colon cancer cells

Anti-angiogenic therapies targeting vascular endothelial growth factor (VEGF) and its receptor (VEGF-R) are important treatments for a number of human malignancies, including colorectal cancers. However, there is increasing evidence that VEGF/VEGF-R inhibitors promote the adaptive and evasive resistance of tumor cells to the therapies. The mechanism by which the cancer cells become resistant remains unclear. One potential mechanism is that VEGF/VEGF-R blockers directly act on tumor cells independently of anti-angiogenic effects. In this study, the direct effects of an anti-VEGF antibody (bevacizumab) and a VEGF-R tyrosine kinase inhibitor (sunitinib) on the evasive adaptation of colon cancer cells were compared. HCT116 and RKO human colon cancer cell lines were chronically exposed (3 months) to bevacizumab or sunitinib in vitro to establish bevacizumab- and sunitinib-adapted cells, respectively. Transwell migration and invasion assays, western blotting, reverse transcription-quantitative polymerase chain reaction, co-immunoprecipitation analysis, cell survival assays and ELISAs were conducted to analyze the adapted cells. Compared with the control vehicle-treated cells, the two cell models exhibited increased migration and invasion activities to different degrees and through different mechanisms. The bevacizumab-adapted cells, but not in the sunitinib-adapted cells, exhibited redundantly increased expression levels of VEGF/VEGF-R family members, including VEGF-A, placental growth factor, VEGF-C, VEGF-R1 and VEGF-R3. In addition, the phosphorylation levels of VEGF-R1 and VEGF-R3 were increased in the bevacizumab-adapted cells compared with the control cells. Thus, the inhibition of VEGF-R1 and VEGF-R3 decreased the evasive activities of the cells, suggesting that they remained dependent on redundant VEGF/VEGF-R signaling. By contrast, the sunitinib-adapted cells exhibited increased neuropilin-1 (NRP1) expression levels compared with the control cells. In the sunitinib-adapted cells, NRP1 interacted with phosphorylated cMet, and the cMet activation was dependent on NRP1. Thus, NRP1 or cMet blockade suppressed the evasive activation of the sunitinib-adapted cells. These results suggest that the sunitinib-adapted cells switched from a VEGF-R-dependent pathway to an alternative NRP1/cMet-dependent one. The findings of the present study indicate that VEGF/VEGF-R inhibitors directly act on colon cancer cells and activate their evasive adaptation via different mechanisms.

Capric Acid Up-Regulates UCP3 Expression without PDK4 Induction in Mouse C2C12 Myotubes

Uncoupling protein 3 (UCP3) and pyruvate dehydrogenase kinase 4 (PDK4) in skeletal muscle are key regulators of the glucose and lipid metabolic processes that are involved in insulin resistance. Medium-chain fatty acids (MCFAs) have anti-obesogenic effects in rodents and humans, while long-chain fatty acids (LCFAs) cause increases in body weight and insulin resistance. To clarify the beneficial effects of MCFAs, we examined UCP3 and PDK4 expression in skeletal muscles of mice fed a MCFA- or LCFA-enriched high-fat diet (HFD). Five-week feeding of the LCFA-enriched HFD caused high body weight gain and induced glucose intolerance in mice, compared with those in mice fed the MCFA-enriched HFD. However, the amounts of UCP3 and PDK4 transcripts in the skeletal muscle of mice fed the MCFA- or LCFA-enriched HFD were similar. To further elucidate the specific effects of MCFAs, such as capric acid (C10:0), on lipid metabolism in skeletal muscles, we examined the effects of various FAs on expression of UCP3 and PDK4, in mouse C2C12 myocytes. Although palmitic acid (C16:0) and lauric acid (C12:0) significantly induced expression of both UCP3 and PDK4, capric acid (C10:0) upregulated only UCP3 expression via activation of peroxisome proliferator-activated receptor-δ. Furthermore, palmitic acid (C16:0) disturbed the insulin-induced phosphorylation of Akt, while MCFAs, including lauric (C12:0), capric (C10:0), and caprylic acid (C12:0), did not. These results suggest that capric acid (C10:0) increases the capacity for fatty acid oxidation without inhibiting glycolysis in skeletal muscle.

The malignant progression effects of regorafenib in human colon cancer cells

A number of anti-angiogenic drugs targeting vascular endothelial growth factor receptors (VEGF-R) have developed and enabled significant advances in cancer therapy including colorectal cancer. However, acquired resistance to the drugs occurs, leading to disease progression, such as invasion and metastasis. How tumors become the resistance and promote their malignancy remains fully uncertain. One of possible mechanisms for the resistance and the progression may be the direct effect of VEGF-R inhibitors on tumor cells expressing VEGF-R. We investigated here the direct effect of a VEGF-R-targeting agent, regorafenib, which is the first small molecule inhibitor of VEGF-Rs for the treatment of patients with colorectal cancer, on phenotype changes in colon cancer HCT116 cells. Treatment of cells with regorafenib for only 2 days activated cell migration and invasion, while vehicle-treated control cells showed less activity. Intriguingly, chronic exposure to regorafenib for 90 days dramatically increased migration and invasion activities and induced a resistance to hypoxia-induced apoptosis. These results suggest that loss of VEGF signaling in cancer cells may induce the acquired resistance to VEGF/VEGF-R targeting therapy by gaining two major malignant phenotypes, apoptosis resistance and activation of migration/invasion.

Effects of dietary soy protein on skeletal muscle volume and strength in humans with various physical activities

BACKGROUND

In recent years, the number of bedridden people is rapidly increasing due to aging or lack of exercise in Japan. This problem is becoming more serious, since there is no countermeasure against it. In the present study, we designed to investigate whether dietary proteins, especially soy, had beneficial effects on skeletal muscle in 59 volunteers with various physical activities.

METHODS

We subjected 59 volunteers with various physical activities to meal intervention examination. Persons with low and high physical activities were divided into two dietary groups, the casein diet group and the soy diet group. They ate daily meals supplemented with 7.8 g of powdered casein or soy protein isolate every day for 30 days. Bedridden patients in hospitals were further divided into three dietary groups: the no supplementation diet group, the casein diet group and the soy diet group. They were also subjected to a blood test, a urinalysis, magnetic resonance imaging analysis and muscle strength test of the knee before and after the meal intervention study.

RESULTS

Thirty-day soy protein supplementation significantly increased skeletal muscle volume in participants with low physical activity, compared with 30-day casein protein supplementation. Both casein and soy protein supplementation increased the volume of quadriceps femoris muscle in bedridden patients. Consistently, soy protein significantly increased their extension power of the knee, compared with casein protein. Although casein protein increased skeletal muscle volume more than soy protein in bedridden patients, their muscle strength changes by soy protein supplementation were bigger than those by casein protein supplementation.

CONCLUSIONS

The supplementation of soy protein would be one of the effective foods which prevent the skeletal muscle atrophy caused by immobilization or unloading.

Flavones Inhibit LPS-Induced Atrogin-1/MAFbx Expression in Mouse C2C12 Skeletal Myotubes

Muscle atrophy is a complex process that occurs as a consequence of various stress events. Muscle atrophy-associated genes (atrogenes) such as atrogin-1/MAFbx and MuRF-1 are induced early in the atrophy process, and the increase in their expression precedes the loss of muscle weight. Although antioxidative nutrients suppress atrogene expression in skeletal muscle cells, the inhibitory effects of flavonoids on inflammation-induced atrogin-1/MAFbx expression have not been clarified. Here, we investigated the inhibitory effects of flavonoids on lipopolysaccharide (LPS)-induced atrogin-1/MAFbx expression. We examined whether nine flavonoids belonging to six flavonoid categories inhibited atrogin-1/MAFbx expression in mouse C2C12 myotubes. Two major flavones, apigenin and luteolin, displayed potent inhibitory effects on atrogin-1/MAFbx expression. The pretreatment with apigenin and luteolin significantly prevented the decrease in C2C12 myotube diameter caused by LPS stimulation. Importantly, the pretreatment of LPS-stimulated myoblasts with these flavones significantly inhibited LPS-induced JNK phosphorylation in C2C12 myotubes, resulting in the significant suppression of atrogin-1/MAFbx promoter activity. These results suggest that apigenin and luteolin, prevent LPS-mediated atrogin-1/MAFbx expression through the inhibition of the JNK signaling pathway in C2C12 myotubes. Thus, these flavones, apigenin and luteolin, may be promising agents to prevent LPS-induced muscle atrophy.

UCP3 is associated with Hax-1 in mitochondria in the presence of calcium ion

Uncoupling protein 3 (UCP3) is known to regulate energy dissipation, proton leakage, fatty acid oxidation, and oxidative stress. To identify the putative protein regulators of UCP3, we performed yeast two-hybrid screens. Here we report that UCP3 interacted with HS-1 associated protein X-1 (Hax-1), an anti-apoptotic protein that was localized in the mitochondria, and is involved in cellular responses to Ca(2+). The hydrophilic sequences within loop 2, and the matrix-localized hydrophilic domain of mouse UCP3, were necessary for binding to Hax-1 at the C-terminal domain, adjacent to the mitochondrial inner membrane. Interestingly, interaction of these proteins occurred in a calcium-dependent manner. Moreover, the NMR spectrum of the C-terminal domain of Hax-1 was dramatically changed by removal of Ca(2+), suggesting that the C-terminal domain of Hax-1 underwent a Ca(2+)-induced conformational change. In the Ca(2+)-free state, the C-terminal Hax-1 tended to unfold, suggesting that Ca(2+) binding may induce protein folding of the Hax-1 C-terminus. These results suggested that the UCP3-Hax-1 complex may regulate mitochondrial functional changes caused by mitochondrial Ca(2+).

[Non-invasive analysis of proteins in living cells using NMR spectroscopy]

NMR spectroscopy enables structural analyses of proteins and has been widely used in the structural biology field in recent decades. NMR spectroscopy can be applied to proteins inside living cells, allowing characterization of their structures and dynamics in intracellular environments. The simplest "in-cell NMR" approach employs bacterial cells; in this approach, live Escherichia coli cells overexpressing a specific protein are subjected to NMR. The cells are grown in an NMR active isotope-enriched medium to ensure that the overexpressed proteins are labeled with the stable isotopes. Thus the obtained NMR spectra, which are derived from labeled proteins, contain atomic-level information about the structure and dynamics of the proteins. Recent progress enables us to work with higher eukaryotic cells such as HeLa and HEK293 cells, for which a number of techniques have been developed to achieve isotope labeling of the specific target protein. In this review, we describe successful use of electroporation for in-cell NMR. In addition, (19)F-NMR to characterize protein-ligand interactions in cells is presented. Because (19)F nuclei rarely exist in natural cells, when (19)F-labeled proteins are delivered into cells and (19)F-NMR signals are observed, one can safely ascertain that these signals originate from the delivered proteins and not other molecules.

A novel myogenic function residing in the 5' non-coding region of Insulin receptor substrate-1 (Irs-1) transcript

Background

There is evidence that several messenger RNAs (mRNAs) are bifunctional RNAs, i.e. RNA transcript carrying both protein-coding capacity and activity as functional non-coding RNA via 5′ and 3′ untranslated regions (UTRs).

Results

In this study, we identified a novel bifunctional RNA that is transcribed from insulin receptor substrate-1 (Irs-1) gene with full-length 5′UTR sequence (FL-Irs-1 mRNA). FL-Irs-1 mRNA was highly expressed only in skeletal muscle tissue. In cultured skeletal muscle C2C12 cells, the FL-Irs-1 transcript functioned as a bifunctional mRNA. The FL-Irs-1 transcript produced IRS-1 protein during differentiation of myoblasts into myotubes; however, this transcript functioned as a regulatory RNA in proliferating myoblasts. The FL-Irs-1 5′UTR contains a partial complementary sequence to Rb mRNA, which is a critical factor for myogenic differentiation. The overexpression of the 5′UTR markedly reduced Rb mRNA expression, and this reduction was fully dependent on the complementary element and was not compensated by IRS-1 protein. Conversely, knockdown of FL-Irs-1 mRNA increased Rb mRNA expression and enhanced myoblast differentiation into myotubes.

Conclusions

Our findings suggest that the FL-Irs-1 transcript regulates myogenic differentiation as a regulatory RNA in myoblasts.

Electronic supplementary material

The online version of this article (doi:10.1186/s12860-015-0054-8) contains supplementary material, which is available to authorized users.

N-myristoylated ubiquitin ligase Cbl-b inhibitor prevents on glucocorticoid-induced atrophy in mouse skeletal muscle

A DGpYMP peptide mimetic of tyrosine(608)-phosphorylated insulin receptor substrate-1 (IRS-1), named Cblin, was previously shown to significantly inhibit Cbl-b-mediated IRS-1 ubiquitination. In the present study, we developed N-myristoylated Cblin and investigated whether it was effective in preventing glucocorticoid-induced muscle atrophy. Using HEK293 cells overexpressing Cbl-b, IRS-1 and ubiquitin, we showed that the 50% inhibitory concentrations of Cbl-b-mediated IRS-1 ubiquitination by N-myristoylated Cblin and Cblin were 30 and 120 μM, respectively. Regarding the DEX-induced atrophy of C2C12 myotubes, N-myristoylated Cblin was more effective than Cblin for inhibiting the DEX-induced decreases in C2C12 myotube diameter and IRS-1 degradation. The inhibitory efficacy of N-myristoylated Cblin on IRS-1 ubiquitination in C2C12 myotubes was approximately fourfold larger than that of Cblin. Furthermore, N-myristoylation increased the incorporation of Cblin into HEK293 cells approximately 10-folds. Finally, we demonstrated that N-myristoylated Cblin prevented the wet weight loss, IRS-1 degradation, and MAFbx/atrogin-1 and MuRF-1 expression in gastrocnemius muscle of DEX-treated mice approximately fourfold more effectively than Cblin. Taken together, these results suggest that N-myristoylated Cblin prevents DEX-induced skeletal muscle atrophy in vitro and in vivo, and that N-myristoylated Cblin more effectively prevents muscle atrophy than unmodified Cblin.

Ubiquitin ligase Cbl-b and obesity-induced insulin resistance

Obesity causes type 2 diabetes, atherosclerosis and cardiovascular diseases by inducing systemic insulin resistance. It is now recognized that obesity is related to chronic low-grade inflammation in adipose tissue. Specifically, activated immune cells infiltrate adipose tissue and cause inflammation. There is increasing evidence that activated macrophages accumulate in the hypertrophied adipose tissue of rodents and humans and induce systemic insulin resistance by secreting inflammatory cytokines. Accordingly, a better understanding of the molecular mechanisms underlying macrophage activation in adipose tissue will facilitate the development of new therapeutic strategies. Currently, little is known about the regulation of macrophage activation, although E3 ubiquitin ligase Casitas B-lineage lymphoma (Cbl)-b was identified recently as a novel negative regulator of macrophage activation in adipose tissue. Cbl-b, which is a suppressor of T- and B-cell activation, inhibits intracellular signal transduction by targeting some tyrosine kinases. Notably, preventing Cbl-b-mediated macrophage activation improves obesity-induced insulin resistance in mice. c-Cbl is another member of the Cbl family that is associated with insulin resistance in obesity. These reports suggest that Cbl-b and c-Cbl are potential therapeutic targets for treating obesity-induced insulin resistance. In this review, we focus on the importance of Cbl-b in macrophage activation in aging-induced and high-fat diet-induced obesity.

Cbl-b is a critical regulator of macrophage activation associated with obesity-induced insulin resistance in mice

We previously reported the potential involvement of casitas B-cell lymphoma-b (Cbl-b) in aging-related murine insulin resistance. Because obesity also induces macrophage recruitment into adipose tissue, we elucidated here the role of Cbl-b in obesity-related insulin resistance. Cbl-b(+/+) and Cbl-b(-/-) mice were fed a high-fat diet (HFD) and then examined for obesity-related changes in insulin signaling. The HFD caused recruitment of macrophages into adipose tissue and increased inflammatory reaction in Cbl-b(-/-) compared with Cbl-b(+/+) mice. Peritoneal macrophages from Cbl-b(-/-) mice and Cbl-b-overexpressing RAW264.7 macrophages were used to examine the direct effect of saturated fatty acids (FAs) on macrophage activation. In macrophages, Cbl-b suppressed saturated FA-induced Toll-like receptor 4 (TLR4) signaling by ubiquitination and degradation of TLR4. The physiological role of Cbl-b in vivo was also examined by bone marrow transplantation and Eritoran, a TLR4 antagonist. Hematopoietic cell-specific depletion of the Cbl-b gene induced disturbed responses on insulin and glucose tolerance tests. Blockade of TLR4 signaling by Eritoran reduced fasting blood glucose and serum interleukin-6 levels in obese Cbl-b(-/-) mice. These results suggest that Cbl-b deficiency could exaggerate HFD-induced insulin resistance through saturated FA-mediated macrophage activation. Therefore, inhibition of TLR4 signaling is an attractive therapeutic strategy for treatment of obesity-related insulin resistance.

Soy Glycinin Contains a Functional Inhibitory Sequence against Muscle-Atrophy-Associated Ubiquitin Ligase Cbl-b

Background. Unloading stress induces skeletal muscle atrophy. We have reported that Cbl-b ubiquitin ligase is a master regulator of unloading-associated muscle atrophy. The present study was designed to elucidate whether dietary soy glycinin protein prevents denervation-mediated muscle atrophy, based on the presence of inhibitory peptides against Cbl-b ubiquitin ligase in soy glycinin protein. Methods. Mice were fed either 20% casein diet, 20% soy protein isolate diet, 10% glycinin diet containing 10% casein, or 20% glycinin diet. One week later, the right sciatic nerve was cut. The wet weight, cross sectional area (CSA), IGF-1 signaling, and atrogene expression in hindlimb muscles were examined at 1, 3, 3.5, or 4 days after denervation. Results. 20% soy glycinin diet significantly prevented denervation-induced decreases in muscle wet weight and myofiber CSA. Furthermore, dietary soy protein inhibited denervation-induced ubiquitination and degradation of IRS-1 in tibialis anterior muscle. Dietary soy glycinin partially suppressed the denervation-mediated expression of atrogenes, such as MAFbx/atrogin-1 and MuRF-1, through the protection of IGF-1 signaling estimated by phosphorylation of Akt-1. Conclusions. Soy glycinin contains a functional inhibitory sequence against muscle-atrophy-associated ubiquitin ligase Cbl-b. Dietary soy glycinin protein significantly prevented muscle atrophy after denervation in mice.

Isoflavones derived from soy beans prevent MuRF1-mediated muscle atrophy in C2C12 myotubes through SIRT1 activation

Proinflammatory cytokines are factors that induce ubiquitin-proteasome-dependent proteolysis in skeletal muscle, causing muscle atrophy. Although isoflavones, as potent antioxidative nutrients, have been known to reduce muscle damage during the catabolic state, the non-antioxidant effects of isoflavones against muscle atrophy are not well known. Here we report on the inhibitory effects of isoflavones such as genistein and daidzein on muscle atrophy caused by tumor necrosis factor (TNF)-α treatment. In C2C12 myotubes, TNF-α treatment markedly elevated the expression of the muscle-specific ubiquitin ligase MuRF1, but not of atrogin-1, leading to myotube atrophy. We found that MuRF1 promoter activity was mediated by acetylation of p65, a subunit of NFκB, a downstream target of the TNF-α signaling pathway; increased MuRF1 promoter activity was abolished by SIRT1, which is associated with deacetylation of p65. Of interest, isoflavones induced expression of SIRT1 mRNA and phosphorylation of AMP kinase, which is well known to stimulate SIRT1 expression, although there was no direct effect on SIRT1 activation. Moreover, isoflavones significantly suppressed MuRF1 promoter activity and myotube atrophy induced by TNF-α in C2C12 myotubes. These results suggest that isoflavones suppress myotube atrophy in skeletal muscle cells through activation of SIRT1 signaling. Thus, the efficacy of isoflavones could provide a novel therapeutic approach against inflammation-related muscle atrophy.

p53 status and prognosis in stage I-IIIa non-small cell lung cancer

To investigate the role of p53 abnormalities in predicting the survival of patients with non-small cell lung cancer (NSCLC), polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and immunohistochemical analyses were performed on 74 and 67 tumor samples, respectively, from patients with pathological stage I-IIIa NSCLC. An abnormally migrating SSCP band was observed in 21 of 74 (28%) tumor specimens. DNA sequence analysis revealed 23 intragenic mutations including 3 small deletions and 20 point mutations. Immunohistochemical analysis using the DO-7 monoclonal antibody showed abnormal expression of p53 in 27 of 67 (40%) patients. The concordance rate between immunohistochemical and PCRSSCP analyses was 73% (49/67) in this study. Univariate and multivariate analyses demonstrated that abnormal expression of p53 may be associated with prolonged survival (p=0.0997 and 0.0099, respectively). In contrast, no relationship was observed between p53 mutation and overall survival (0.6968). These results suggest that p53 status and the survival outcome changes between immunohistochemical and mutational analyses in stage I-IIIa NSCLC.

Unloading stress disturbs muscle regeneration through perturbed recruitment and function of macrophages

Skeletal muscle is one of the most sensitive tissues to mechanical loading, and unloading inhibits the regeneration potential of skeletal muscle after injury. This study was designed to elucidate the specific effects of unloading stress on the function of immunocytes during muscle regeneration after injury. We examined immunocyte infiltration and muscle regeneration in cardiotoxin (CTX)-injected soleus muscles of tail-suspended (TS) mice. In CTX-injected TS mice, the cross-sectional area of regenerating myofibers was smaller than that of weight-bearing (WB) mice, indicating that unloading delays muscle regeneration following CTX-induced skeletal muscle damage. Delayed infiltration of macrophages into the injured skeletal muscle was observed in CTX-injected TS mice. Neutrophils and macrophages in CTX-injected TS muscle were presented over a longer period at the injury sites compared with those in CTX-injected WB muscle. Disturbance of activation and differentiation of satellite cells was also observed in CTX-injected TS mice. Further analysis showed that the macrophages in soleus muscles were mainly Ly-6C-positive proinflammatory macrophages, with high expression of tumor necrosis factor-α and interleukin-1β, indicating that unloading causes preferential accumulation and persistence of proinflammatory macrophages in the injured muscle. The phagocytic and myotube formation properties of macrophages from CTX-injected TS skeletal muscle were suppressed compared with those from CTX-injected WB skeletal muscle. We concluded that the disturbed muscle regeneration under unloading is due to impaired macrophage function, inhibition of satellite cell activation, and their cooperation.

A carrier fusion significantly induces unfolded protein response in heterologous protein production by Aspergillus oryzae

In heterologous protein production by filamentous fungi, target proteins are expressed as fusions with homologous secretory proteins, called carriers, for higher production yields. Although carrier fusion is thought to overcome the bottleneck in transcriptional and (post)translational processes during heterologous protein production, there is limited knowledge of its physiological effects on the host strain. In this study, we performed DNA microarray analysis by comparing gene expression patterns of two Aspergillus oryzae strains expressing either carrier- or non-carrier-fused bovine chymosin (CHY). When CHY was expressed as a fusion with α-amylase (AmyB), the production level increased by approximately 2-fold as compared with the non-carrier-fused CHY. DNA microarray analysis revealed that the carrier fusion significantly up-regulated many genes involved in endoplasmic reticulum (ER) protein-folding and secretion. Consistently, hacA transcripts were efficiently spliced in the strain expressing the carrier-fused CHY, indicating an unfolded protein response (UPR). The carrier-fused CHY was detected intracellularly without processing at the Kex2 cleavage site, which is likely recognized in the Golgi, and the carrier fusion delayed extracellular CHY production in the early growth phase as compared with the non-carrier-fused expression. Taken together, our data suggest a proposal that the carrier fusion temporarily accumulates the carrier-fused CHY in the ER and significantly induces UPR.

Application of NMR spectroscopy in medicinal chemistry and drug discovery

"In-cell nuclear magnetic resonance (NMR)" is a unique method for characterization of conformation, interaction and dynamics of proteins inside living cells at atomic level. Since the method was proposed by Dötch and co-workers in 2001 [1], its application had been limited to bacterial cells and oocytes of Xenopus laevis [2]. Recently, we reported a method for efficient delivery of (15)N-labeled proteins into human HeLa cells using cell-penetrating peptides, and measured high-resolution two-dimensional (1)H-(15)N correlation spectra of proteins in the cells. The in-cell NMR spectroscopy in human cells is capable of analyzing structures, interactions, dynamics and stability of proteins inside cells. Of its possible applications, we propose that in-cell NMR spectroscopy can be utilized as an effective step in protein-targeted drug development process, by demonstrating that interaction of FKBP12 with immunosuppressants administered extracellularly was successfully observed in living cells. This observation suggests that drug delivery and capability of target proteins inside cells for interaction with drugs can be investigated by in-cell NMR spectroscopy. More recently, an alternative way for intracellular delivery of labeled proteins for in-cell NMR was reported on 293F cells by Shimada and co-workers. Here, we review recent technical developments of in-cell NMR spectroscopy, and discuss potential usefulness for protein chemistry and drug screening process.

An increased dose of insulin detemir improves glycaemic control and reduces body weight of Japanese patients with diabetes

AIMS

The aim of study was to evaluate the safety and efficacy of insulin detemir as a basal insulin switching from neutral protamine Hagedorn insulin (NPH) and insulin glargine in patients with diabetes on an intensive insulin therapy regimen.

METHODS

This 6-month multicentre, prospective, treat-to-target [glycosylated haemoglobin (HbA(1c) ) less than 6.5%] trial included 92 people with diabetes (61 type 1, 29 type 2 and two unknown diabetes types). Detemir was administered first with fixed dose and injection times and then adapted to optimal dose after 3 months.

RESULTS

Mean HbA(1c) (%) of all the subjects at months 4 to 6 of the study was improved compared with month 0 (7.34 ± 0.87, 7.28 ± 0.88, 7.25 ± 0.93 vs. 7.55 ± 1.18; p < 0.05 paired t-test). However, significant improvement was seen only among the patients who had previously used NPH as a basal insulin. Twice-daily injection of basal insulin increased among people in the type 1 previously injected insulin glargine. Total insulin dose increased in the type 1 glargine group. The mean body weight change in the highest quartile body mass index (BMI) group was from 70.7 to 69.3 kg over the 6 months. Quality of life (QoL) relating to the patients' glycaemic control tended to improve without a change in frequency of hypoglycaemia.

CONCLUSIONS

The results suggest that insulin detemir has a greater effect on glycaemic control in subjects with poor glycaemic control using NPH; can reduce or maintain body weight in obese patients; and obtains perceptive stability for patients with unstable glycaemic control.

Characterization of human multicentric osteosarcoma using newly established cells derived from multicentric osteosarcoma

PURPOSE

Human multicentric osteosarcoma (HMOS) is a rare, aggressive variant of osteosarcoma, and its etiology is not clear. We used newly established HMOS cells, which were derived from primary (HMOS-A) and secondary (HMOS-P) lesions, respectively, to perform a basic study analyzing the cellular biology and gene expression of HMOS.

METHODS

We performed a cell growth assay, an invasion assay, DNA microarray analysis, quantitative real-time RT-PCR (Qrt-PCR), and a telomerase assay and compared the results between HMOS-A, HMOS-P, and human osteosarcoma (HOS) cell lines (MNNG-HOS and Saos-2).

RESULTS

The cell biological analysis revealed that HMOS-A and HMOS-P had similar characteristics to Saos-2, and the invasion assay showed that they had similar characteristics to MNNG-HOS. The DNA microarray study showed that the gene expression profiles of HMOS-A and HMOS-P were similar to that of MNNG-HOS, but the overexpression of MMP-2, MMP-9, and MT1-MMP was observed in HMOS-A and HMOS-P, which was correlated with the invasiveness of the extracellular matrix, and collagen type-4 (COL-4) and VEGF were also detected. HMOS-A and HMOS-P showed low telomerase activity similar to Saos-2, which are known to be telomerase negative, but a similar telomere length and telomerase protein to MNNG-HOS.

CONCLUSIONS

HMOS-A and HMOS-P demonstrated strong invasive ability, and their gene expression profiles correlated with the invasiveness of the extracellular matrix. Their telomerase activity was low, but they did not shown the typical features of alternative lengthening of telomeres (ALT). HMOS-A and HMOS-P are useful models for further study of various biological aspects and therapeutic manipulation of HMOS.

Delirious behavior in children with acute necrotizing encephalopathy

OBJECTIVE

To clarify the features of delirious behavior in patients with acute necrotizing encephalopathy.

METHODS

We retrospectively evaluated the clinical course of 38 children with acute necrotizing encephalopathy diagnosed on the basis of neuroradiological findings. The patients were divided into two groups according to the presence or absence of delirious behavior. We compared clinical features, laboratory data, neuroimaging findings, and outcome between those with and without delirious behavior. In patients with delirious behavior, chronological sequence of neurological symptoms and the characteristics of delirious behavior were investigated.

RESULTS

Delirious behavior was observed in 8 patients. Patient characteristics or most laboratory data on admission were not significantly different between those with and without delirious behavior. Brainstem lesions were more frequent in patients with delirious behavior than in those without. In contrast, lesions in lentiform nuclei, cerebral hemisphere, or cerebellum were relatively more frequent in patients without delirious behavior. It was the initial neurological symptom in 7 of 8 patients. Stupor and seizures were observed after delirious behavior in most patients.

CONCLUSIONS

Delirious behavior was not uncommon in children with acute necrotizing encephalopathy. Brainstem lesions may be related to the development of delirious behavior of children with acute necrotizing encephalopathy.

[Frequency and prevention of childhood domestic injury according to age]

OBJECTIVE

This study aimed to: 1) obtain data about occurrence of childhood domestic injuries in Gunma prefecture according to children's age; 2) ascertain parental awareness of injury prevention; and 3) develop ideas for creating concrete strategies of childhood injury prevention.

METHODS

The participants were 551 parents of children living in 14 cities/towns in Gunma prefecture that showed interest in cooperating with this survey. A self-reported questionnaire was handed to parents when they took their children to health check-ups provided by the cities/towns either during the child's first year, at 18 months, or at 3 years. Parents completed the questionnaire asking whether their child had been injured at home during the past year, and if so, they were asked about the type of injury, the cause of injury, and what action they took. We also asked whether the parents took specific injury prevention measures at home. Data were analyzed statistically.

RESULTS

The injury experienced most frequently during the first year of life was "fall" (30.8%), followed by "ingestion of a foreign body" (22.7%), and then "choking" (11.5%). For children around the age of 18 months, the most frequently experienced injury was "fall" (41.0%), followed by "burn" (20.3%), and "ingestion of a foreign body" (19.3%). At 3 years, "burn" was reported most frequently (32.3%), followed by "fall" (31.0%), and "choking" (14.5%). Chi2-test revealed significant correlations among the three age groups concerning the rate of burn injury, foreign body ingestion, and drowning. The rate of burn injury was higher at 3 years than at 18 months, and also higher at 18 months as compared to under the age of one. In contrast, the rate of foreign body ingestion was higher under the age of one than at 18 months, and also higher at 18 months as compared to the age of 3 years. Drowning was more common at 18 months and 3 years than under the age of one. As for prevention of domestic injury, investigation of preventive means taken according to type of injury revealed that parents taking any of the measures to prevent an injury were significantly more likely to also take other means to prevent that injury.

CONCLUSION

Characteristics of injury differed according to children's age. Furthermore, it was clarified that parents' performance of injury prevention depends on their awareness of preventive measures.

The solution structure of the C-terminal domain of NfeD reveals a novel membrane-anchored OB-fold

Nodulation formation efficiency D (NfeD) is a member of a class of membrane-anchored ClpP-class proteases. There is a second class of NfeD homologs that lack the ClpP domain. The genes of both NfeD classes usually are part of an operon that also contains a gene for a prokaryotic homolog of stomatin. (Stomatin is a major integral-membrane protein of mammalian erythrocytes.) Such NfeD/stomatin homolog gene pairs are present in more than 290 bacterial and archaeal genomes, and their protein products may be part of the machinery used for quality control of membrane proteins. Herein, we report the structure of the isolated C-terminal domain of PH0471, a Pyrococcus horikoshii NfeD homolog, which lacks the ClpP domain. This C-terminal domain (termed NfeDC) contains a five-strand beta-barrel, which is structurally very similar to the OB-fold (oligosaccharide/oligonucleotide-binding fold) domain. However, there is little sequence similarity between it and previously characterized OB-fold domains. The NfeDC domain lacks the conserved surface residues that are necessary for the binding of an OB-fold domain to DNA/RNA, an ion. Instead, its surface is composed of residues that are uniquely conserved in NfeD homologs and that form the structurally conserved surface turns and beta-bulges. There is also a conserved tryptophan present on the surface. We propose that, in general, NfeDC domains may interact with other spatially proximal membrane proteins and thereby regulate their activities.

Functional adaptation of Nef to the immune milieu of HIV-1 infection in vivo

Nef-mediated down-regulation of MHC class I (MHC-I) molecules on HIV-1-infected cells has been proposed to enhance viral persistence through evasion of host CTLs. This conclusion is based largely on demonstrations that Nef from laboratory HIV-1 strains reduces the susceptibility of infected cells to CTL killing in vitro. However, the function and role of Nef-mediated MHC-I down-regulation in vivo have not been well described. To approach this issue, nef quasispecies from chronically HIV-1-infected individuals were cloned into recombinant reporter viruses and tested for their ability to down-regulate MHC-I molecules from the surface of infected cells. The level of function varied widely between individuals, and although comparison to the immunologic parameters of blood CD4(+) T lymphocyte count and breadth of the HIV-1-specific CTL response showed positive correlations, no significant correlation was found in comparison to plasma viremia. The ability of in vivo-derived Nef to down-regulate MHC-I predicted the resistance of HIV-1 to suppression by CTL. Taken together, these data demonstrate the functionality of Nef to down-regulate MHC-I in vivo during stable chronic infection, and suggest that this function is maintained by the need of HIV-1 to cope with the antiviral CTL response.

Structural characterization of the MIT domain from human Vps4b

The microtubule interacting and trafficking (MIT) domain is a small protein module of unknown function that is conserved in proteins of diverse function, such as Vps4, sorting nexin 15 (SNX15), and spastin. One non-synonymous single nucleotide polymorphism was reported, which results in a Ile58-to-Met (I58M) substitution in hVps4b. Here, we have determined the solution structure of the MIT domain isolated from the NH(2)-terminus of human Vps4b, an AAA-ATPase involved in multivesicular body formation. The MIT domain adopts an 'up-and-down' three-helix bundle. Comparison with the sequences of other MIT domains clearly shows that the residues involved in inter-helical contacts are well conserved. The Ile58-to-Met substitution resulted a substantial thermal instability. In addition, we found a shallow crevice between helices A and C that may serve as a protein-binding site. We propose that the MIT domain serves as a putative adaptor domain for the ESCRT-III complex involved in endosomal trafficking.

Structure of the UBA domain of Dsk2p in complex with ubiquitin molecular determinants for ubiquitin recognition

The ubiquitin-associated (UBA) domain is one of the most frequently occurring motifs that recognize ubiquitin tags. Dsk2p, a UBA-containing protein from Saccharomyces cerevisiae, is involved in the ubiquitin-proteasome proteolytic pathway and has been implicated in spindle pole duplication. Here we present the solution structure of the UBA domain of Dsk2p (Dsk2(UBA)) in complex with ubiquitin. The structure reveals that the UBA domain uses a mode of ubiquitin recognition that is similar to that of the CUE domain, another ubiquitin binding motif that shares low sequence homology but high structural similarity with UBA domains. These two domains, as well as the structurally unrelated ubiquitin binding motif UIM, provide a common, crucial recognition site for ubiquitin, comprising a hydrogen-bonding acceptor for the amide group of Gly-47, and a methyl group that packs against the hydrophobic pocket of ubiquitin formed by Leu-8, Ile-44, His-68, and Val-70.

Dermatomyositis associated with Sjögren's syndrome: VEGF involvement in vasculitis

Two patients with dermatomyositis complicated with Sjögren's syndrome (SjS), are reported. Both patients exhibited sensory-dominant polyneuropathy, compatible with neurologic involvement in SjS. Vascular endothelial growth factor (VEGF) levels were increased in their plasma. Histological examination demonstrated vasculitic changes in biopsied specimens of muscle and salivary glands from the patients, and VEGF was overexpressed in the vasculitic lesions. These findings suggest that VEGF overexpression was associated with the development of vasculopathy in skeletal muscle and salivary glands and possibly in the peripheral nervous system.

Functional characterization of three human cytochrome p450 2E1 variants with amino acid substitutions

1. Cytochrome p450 (p450) 2E1 is a hepatic enzyme of importance for the metabolism of xenobiotics such as drugs and environmental toxicants. Genetic polymorphisms of CYP2E1 in 5'-flanking and coding regions have been found previously in Caucasian and Chinese populations. 2. In order to investigate the effects of amino acid substitutions on the function of CYP2E1, the enzymes of all known CYP2E1 variants in the coding region (CYP2E1.2, CYP2E1.3 and CYP2E1.4) with Arg76His, Val389Ile and Val179Ile substitutions, respectively, as well as the wild-type CYP2E1 (CYP2E1.1) were expressed in COS-1 cells, and their chlorzoxazone 6-hydroxylation and 4-nitrophenol 2-hydroxylation activities were determined. 3. The protein level of CYP2E1.2 was reduced to 29% compared with that of CYP2E1.1. The profiles of the level of activity relative to CYP2E1.1 for chlorzoxazone 6-hydroxylation (300 microM substrate) and 4-nitrophenol 2-hydroxylation (150 microM substrate) were very similar. 4. Although the K(m) values were not significantly different among wild-type and variant CYP2E1s in any oxidation metabolism, the V(max) and V(max)/K(m) of CYP2E1.2 on the basis of the CYP2E1 protein level were 2.7-3.0-fold higher than those of CYP2E1.1. In contrast, the levels of CYP2E1 protein and catalytic activity of CYP2E1.3 and CYP2E1.4 were not affected by the corresponding amino acid substitutions. 5. The findings suggest that Arg76 is closely associated with the function of CYP2E1, and that the genetic polymorphism of CYP2E1 is one cause of interindividual differences in the toxicity of xenobiotics.