GTDC2 modifies O-mannosylated α-dystroglycan in the endoplasmic reticulum to generate N-acetyl glucosamine epitopes reactive with CTD110.6 antibody

Hypoglycosylation is a common characteristic of dystroglycanopathy, which is a group of congenital muscular dystrophies. More than ten genes have been implicated in α-dystroglycanopathies that are associated with the defect in the O-mannosylation pathway. One such gene is GTDC2, which was recently reported to encode O-mannose β-1,4-N-acetylglucosaminyltransferase. Here we show that GTDC2 generates CTD110.6 antibody-reactive N-acetylglucosamine (GlcNAc) epitopes on the O-mannosylated α-dystroglycan (α-DG). Using the antibody, we show that mutations of GTDC2 identified in Walker-Warburg syndrome and alanine-substitution of conserved residues between GTDC2 and EGF domain O-GlcNAc transferase resulted in decreased glycosylation. Moreover, GTDC2-modified GlcNAc epitopes are localized in the endoplasmic reticulum (ER). These data suggested that GTDC2 is a novel glycosyltransferase catalyzing GlcNAcylation of O-mannosylated α-DG in the ER. CTD110.6 antibody may be useful to detect a specific form of GlcNAcylated O-mannose and to analyze defective O-glycosylation in α-dystroglycanopathies.

Neuronal Loss and Decreased GLT-1 Expression Observed in the Spinal Cord of Pembroke Welsh Corgi Dogs With Canine Degenerative Myelopathy

Canine degenerative myelopathy (DM) is a progressive neurodegenerative disease that is frequently found in Pembroke Welsh Corgi (PWC) dogs. Canine DM is potentially a spontaneous animal model for human amyotrophic lateral sclerosis (ALS) because of similar lesions and the involvement of superoxide dismutase 1 (SOD1) mutation. However, the ventral horn lesion in DM has not been characterized in detail. Glutamate excitotoxicity due to deficiency of the glutamine-glutamate cycle has been implicated in neuron death in ALS. Thus, we examined 5 PWC dogs with an SOD1 mutation that were affected by DM, 5 non-DM PWC dogs, and 5 Beagle dogs without neurologic signs to assess the neuronal changes and the expression levels of 2 glial excitatory amino acid transporters (glutamate transporter 1 [GLT-1] and glutamate/aspartate transporter [GLAST]). The number of neurons in the spinal ventral horns of the DM dogs was significantly decreased, whereas no change was found in the cell size. Chromatolysis, lipofuscin-laden neurons, and marked synapse loss were also observed. GLT-1 expression was strikingly decreased in DM dogs, whereas GLAST expression showed no significant change. The results indicate that excitotoxicity related to the reduced expression of GLT-1, but not GLAST, may be involved in neuron loss in DM, as in human ALS, whereas intraneuronal events may differ between the 2 diseases.

The physico-chemical properties and protein denaturation potential of surfactant mixtures

Synopsis Protein denaturation was investigated to establish an in vitro evaluation method of surfactants in connection with their in vivo irritation potency to human skin. Eventually a new method with simplicity and high reproducibility was established by using quantitative analysis with gel-permeation chromatography (GPC). The protein denaturing potency of the commercially available surfactants was measured by using the developed method. Synergistic reduction in protein denaturation was observed in the mixed systems of anionic and amphoteric surfactants. The synergistic reduction was explained in terms of the physico-chemical properties of the mixed surfactants. A possible mechanism is the remarkable lowering of the total monomer concentration by the formation of hydrophobic complexes between the anionic and amphoteric surfactants.

Terminal complement inhibitor eculizumab in atypical hemolytic-uremic syndrome

BACKGROUND

Atypical hemolytic-uremic syndrome is a genetic, life-threatening, chronic disease of complement-mediated thrombotic microangiopathy. Plasma exchange or infusion may transiently maintain normal levels of hematologic measures but does not treat the underlying systemic disease.

METHODS

We conducted two prospective phase 2 trials in which patients with atypical hemolytic-uremic syndrome who were 12 years of age or older received eculizumab for 26 weeks and during long-term extension phases. Patients with low platelet counts and renal damage (in trial 1) and those with renal damage but no decrease in the platelet count of more than 25% for at least 8 weeks during plasma exchange or infusion (in trial 2) were recruited. The primary end points included a change in the platelet count (in trial 1) and thrombotic microangiopathy event-free status (no decrease in the platelet count of >25%, no plasma exchange or infusion, and no initiation of dialysis) (in trial 2).

RESULTS

A total of 37 patients (17 in trial 1 and 20 in trial 2) received eculizumab for a median of 64 and 62 weeks, respectively. Eculizumab resulted in increases in the platelet count; in trial 1, the mean increase in the count from baseline to week 26 was 73×10(9) per liter (P<0.001). In trial 2, 80% of the patients had thrombotic microangiopathy event-free status. Eculizumab was associated with significant improvement in all secondary end points, with continuous, time-dependent increases in the estimated glomerular filtration rate (GFR). In trial 1, dialysis was discontinued in 4 of 5 patients. Earlier intervention with eculizumab was associated with significantly greater improvement in the estimated GFR. Eculizumab was also associated with improvement in health-related quality of life. No cumulative toxicity of therapy or serious infection-related adverse events, including meningococcal infections, were observed through the extension period.

CONCLUSIONS

Eculizumab inhibited complement-mediated thrombotic microangiopathy and was associated with significant time-dependent improvement in renal function in patients with atypical hemolytic-uremic syndrome. (Funded by Alexion Pharmaceuticals; C08-002 ClinicalTrials.gov numbers, NCT00844545 [adults] and NCT00844844 [adolescents]; C08-003 ClinicalTrials.gov numbers, NCT00838513 [adults] and NCT00844428 [adolescents]).

Peripheral Quantitative CT (pQCT) Using a Dedicated Extremity Cone-Beam CT Scanner

PURPOSE

We describe the initial assessment of the peripheral quantitative CT (pQCT) imaging capabilities of a cone-beam CT (CBCT) scanner dedicated to musculoskeletal extremity imaging. The aim is to accurately measure and quantify bone and joint morphology using information automatically acquired with each CBCT scan, thereby reducing the need for a separate pQCT exam.

METHODS

A prototype CBCT scanner providing isotropic, sub-millimeter spatial resolution and soft-tissue contrast resolution comparable or superior to standard multi-detector CT (MDCT) has been developed for extremity imaging, including the capability for weight-bearing exams and multi-mode (radiography, fluoroscopy, and volumetric) imaging. Assessment of pQCT performance included measurement of bone mineral density (BMD), morphometric parameters of subchondral bone architecture, and joint space analysis. Measurements employed phantoms, cadavers, and patients from an ongoing pilot study imaged with the CBCT prototype (at various acquisition, calibration, and reconstruction techniques) in comparison to MDCT (using pQCT protocols for analysis of BMD) and micro-CT (for analysis of subchondral morphometry).

RESULTS

The CBCT extremity scanner yielded BMD measurement within ±2-3% error in both phantom studies and cadaver extremity specimens. Subchondral bone architecture (bone volume fraction, trabecular thickness, degree of anisotropy, and structure model index) exhibited good correlation with gold standard micro-CT (error ~5%), surpassing the conventional limitations of spatial resolution in clinical MDCT scanners. Joint space analysis demonstrated the potential for sensitive 3D joint space mapping beyond that of qualitative radiographic scores in application to non-weight-bearing versus weight-bearing lower extremities and assessment of phalangeal joint space integrity in the upper extremities.

CONCLUSION

The CBCT extremity scanner demonstrated promising initial results in accurate pQCT analysis from images acquired with each CBCT scan. Future studies will include improved x-ray scatter correction and image reconstruction techniques to further improve accuracy and to correlate pQCT metrics with known pathology.

Requirement of decreased O-GlcNAc glycosylation of Mef2D for its recruitment to the myogenin promoter

Previously, we demonstrated that the expression of myogenin, a critical transcription factor for myogenesis, is negatively regulated by O-linked β-N-acetylglucosamine (O-GlcNAc) glycosylation in mouse C2C12 cells. In this study, we found that Mef2 family proteins, especially Mef2D which is a crucial transcriptional activator of myogenin, are O-GlcNAc glycosylated. Between the two splice variants of Mef2D, Mef2D1a rather than Mef2D1b appears to drive the initiation of myogenin expression in the early stage of myogenesis. A deletion mutant analysis showed that Mef2D1a is glycosylated both in its DNA-binding and transactivation domains. A significant decrease in the glycosylation of Mef2D was observed in response to myogenic stimulus in C2C12 cells. Inhibition of the myogenesis-dependent decrease in the glycosylation of Mef2D suppressed its recruitment to the myogenin promoter. These results indicate that the expression of myogenin is regulated, at least in part, by the decreased glycosylation-dependent recruitment of Mef2D to the promoter region, and this is one of the negative regulatory mechanisms of skeletal myogenesis by O-GlcNAc glycosylation.

Elevations of serum C-reactive protein occur independently of circulating interleukin-6 concentrations in patients with lung-cancer

It has been suggested that a proportion of patients with cancer have an ongoing acute phase response indicated by a raised C-reactive protein (CRP). To examine whether an acute phase protein response is associated with circulating interleukin-6 (IL-6) concentrations in patients with lung cancer, we measured serum levels of CRP and interleukin (IL)-6 in 176 patients with lung cancer and 48 patients with other pulmonary diseases (28 diffuse pulmonary infiltrates, 15 benign lung tumors, and 5 bronchial asthmas). Serum CRP was detectable (greater-than-or-equal-to 2.5 mg/liter) in 57.4% of patients with lung cancer, 78.6% of patients with diffuse pulmonary infiltrates, 46.7% of patients with benign lung tumors, and 40.0% of patients with bronchial asthma. Serum IL-6 was detectable in all patients by a highly sensitive enzyme-immunoassay, the concentration ranging from 0.126 to 35.115 pg/ml. Although there was no significant difference in serum IL-6 levels among the histologic types of lung cancer, the IL-6 concentration was significantly higher in patients with advanced cancers than in those with early ones. Correlation analyses showed that there was no significant relationship between the CRP and IL-6 concentrations in the 176 patients with lung cancer (r=0.212, P=0.1243), while a highly significant correlation between both levels was observed in the 28 patients with diffuse pulmonary infiltrates (r=0.783, P=0.0005). These results indicate that the serum IL-6 level in patients with lung cancer is closely associated with the disease stage, but that a raised CRP concentration occurs independently of circulating IL-6 concentrations in patients with lung cancer.

Cell biologic factors and cancer spread

There is an increasing body of literature linking expression of cell biologic factors such as proteases and bioactive peptides with tumor malignancy. Cancer cells and/or the surrounding stromal cells produce and secrete a series of different factors which may facilitate tumor cell invasion and subsequent metastasis. Several reviews that cover the literature on the role of these factors are available. Therefore in this report, we focus on the work in our own laboratories. We will review our previous studies of five cell biologic factors which are differentially involved in cancer progression, including urokinase, tissue-type plasminogen activator, polymorphonuclear leukocyte elastase, group II phospholipase A(2), and endothelin-1.

Primary tumor levels of interleukin-6 in relation to tumor burden in human breast-cancer

To examine whether tissue levels of interleukin 6 (IL-6) are associated with the clinicopathologic status in human breast cancer, immunoreactive IL-6 concentration was measured in tumor extracts of 75 breast cancer patients. IL-6 was detectable in 69 of 75 tumor extracts by enzyme-linked immunosorbent assay, the concentration ranging from 10 to 10.690 pg/mg protein. When breast cancer specimens were categorized into four groups in terms of clinical stage of disease at diagnosis, IL-6 concentration (mean +/- SE) in tissue extracts was significantly higher in stage IV patients (2859 +/- 840 pg/mg protein) than in stage I-III patients (344 +/- 117, 350 +/- 150 and 564 +/- 230 pg/mg protein, respectively). Correlation analyses between IL-6 concentration and clinicopathologic factors showed that tissue levels of IL-6 were significantly higher in patients with distant metastasis compared with those without. Furthermore, IL-6 concentration was significantly higher in tumors of more than 5.0 cm in size as compared to less than 5.0 cm. However, no significant association was found between IL-6 concentration and age, histological type, histological grade, lymph node involvement, or hormone receptor status. These results suggest that primary tumor levels of IL-6 are closely associated with clinical stage in human breast cancer.

Controlling the topology of Fermi surfaces in metal nanofilms

The properties of metal crystals are governed by the electrons of the highest occupied states at the Fermi level and determined by Fermi surfaces, the Fermi energy contours in momentum space. Topological regulation of the Fermi surface has been an important issue in synthesizing functional materials, which we found to be realized at room temperature in nanometer-thick films. Reducing the thickness of a metal thin film down to its electron wavelength scale induces the quantum size effect and the electronic system changes from three to two-dimensional, transforming the Fermi surface topology. Such an ultrathin film further changes its topology through one-dimensional (1D) structural deformation of the film when it is grown on a 1D substrate. In particular, when the interface has 1D metallic bands, the system is additionally stabilized by forming an electron energy gap by hybridization between 1D states of the film and substrate.

Depression of mitochondrial metabolism by downregulation of cytoplasmic deacetylase, HDAC6

Mitochondria perform multiple functions critical to the maintenance of cellular homeostasis. Here we report that the downregulation of histone deacetylase 6 (HDAC6) causes a reduction in the net activity of mitochondrial enzymes, including respiratory complex II and citrate synthase. HDAC6 deacetylase and ubiquitin-binding activities were both required for recovery of reduced mitochondrial metabolic activity due to the loss of HDAC6. Hsp90, a substrate of HDAC6, localizes to mitochondria and partly mediates the regulation of mitochondrial metabolic activity by HDAC6. Our finding suggests that HDAC6 regulates mitochondrial metabolism and might serve as a cellular homeostasis surveillance factor.