Turnover of C99 is Controlled by a Crosstalk between ERAD and Ubiquitin-Independent Lysosomal Degradation in Human Neuroglioma Cells

Alzheimer’s disease (AD) is characterized by the buildup of amyloid-β peptides (Aβ) aggregates derived from proteolytic processing of the β-amyloid precursor protein (APP). Amyloidogenic cleavage of APP by β-secretase/BACE1 generates the C-terminal fragment C99/CTFβ that can be subsequently cleaved by γ-secretase to produce Aβ. Growing evidence indicates that high levels of C99/CTFβ are determinant for AD. Although it has been postulated that γ-secretase-independent pathways must control C99/CTFβ levels, the contribution of organelles with degradative functions, such as the endoplasmic reticulum (ER) or lysosomes, is unclear. In this report, we investigated the turnover and amyloidogenic processing of C99/CTFβ in human H4 neuroglioma cells, and found that C99/CTFβ is localized at the Golgi apparatus in contrast to APP, which is mostly found in endosomes. Conditions that localized C99/CTFβ to the ER resulted in its degradation in a proteasome-dependent manner that first required polyubiquitination, consistent with an active role of the ER associated degradation (ERAD) in this process. Furthermore, when proteasomal activity was inhibited C99/CTFβ was degraded in a chloroquine (CQ)-sensitive compartment, implicating lysosomes as alternative sites for its degradation. Our results highlight a crosstalk between degradation pathways within the ER and lysosomes to avoid protein accumulation and toxicity.     

Associations between Level and Change in Physical Function and Brain Volumes

Background

Higher levels of fitness or physical function are positively associated with cognitive outcomes but the potential underlying mechanisms via brain structure are still to be elucidated in detail. We examined associations between brain structure and physical function (contemporaneous and change over the previous three years) in community-dwelling older adults.

Methodology/Principal Findings

Participants from the Lothian Birth Cohort 1936 (N=694) underwent brain MRI at age 73 years to assess intracranial volume, and the volumes of total brain tissue, ventricles, grey matter, normal-appearing white matter, and white matter lesions. At ages 70 and 73, physical function was assessed by 6-meter walk, grip strength, and forced expiratory volume. A summary ‘physical function factor’ was derived from the individual measures using principal components analysis. Performance on each individual physical function measure declined across the three year interval (p<0.001). Higher level of physical function at ages 70 and 73 was associated with larger total brain tissue and white matter volumes, and smaller ventricular and white matter lesion volumes (standardized β ranged in magnitude from 0.07 to 0.17, p<0.001 to 0.034). Decline in physical function from age 70 to 73 was associated with smaller white matter volume (0.08, p<0.01, though not after correction for multiple testing), but not with any other brain volumetric measurements.

Conclusions/Significance

Physical function was related to brain volumes in community-dwelling older adults: declining physical function was associated with less white matter tissue. Further study is required to explore the detailed mechanisms through which physical function might influence brain structure, and vice versa.     

Virological Efficacy in Cerebrospinal Fluid and Neurocognitive Status in Patients with Long-Term Monotherapy Based on Lopinavir/Ritonavir: An Exploratory Study

Background

Data on suppression of HIV replication in the CNS and on the subsequent risk of neurocognitive impairment using monotherapy with boosted protease inhibitors are limited.

Methods

Ours was an exploratory cross-sectional study in patients on lopinavir/ritonavir-based monotherapy (LPV/r-MT) or standard triple therapy (LPV/r-ART) for at least 96 weeks who maintained a plasma viral load <50 copies/mL. HIV-1 RNA in CSF was determined by HIV-1 SuperLow assay (lower limit of detection, 1 copy/mL). Neurocognitive functioning was assessed using a recommended battery of neuropsychological tests covering 7 areas. Neurocognitive impairment (NCI) was determined and also a global deficit score (GDS) for study comparisons.

Results

Seventeen patients on LPV/r-MT and 17 on LPV/r-ART were included. Fourteen (82.4%) patients on LPV/r-MT and 16 (94.1%) on LPV/r-ART had HIV-1 RNA <1 copy/mL in CSF (p = 0.601). NCI was observed in 7 patients on LPV/r-MT and in 10 on LPV/r-ART (41% vs 59%; p = 0.494). Mean (SD) GDS was 0.22 (0.20) in patients on LPV/r-MT and 0.47 (0.34) in those on LPV/r-ART (p = 0.012).

Conclusions

Suppression of HIV in CSF is similar in individuals with durable plasma HIV-1 RNA suppression who are receiving LPV/r-MT or LPV/r-ART for at least 96 weeks. Findings for HIV-1 replication in CSF and neurocognitive status indicate that this strategy seems to be safe for CNS functioning.     

The History and Advances of Reversible Terminators Used in New Generations of Sequencing Technology

DNA sequencing using reversible terminators, as one sequencing by synthesis strategy, has garnered a great deal of interest due to its popular application in the second-generation high-throughput DNA sequencing technology. In this review, we provided its history of development, classification, and working mechanism of this technology. We also outlined the screening strategies for DNA polymerases to accommodate the reversible terminators as substrates during polymerization; particularly, we introduced the "REAP" method developed by us. At the end of this review, we discussed current limitations of this approach and provided potential solutions to extend its application.     

Prevalencia de sobrepeso y obesidad en niños y adolescentes de 2 a 16 años

ObjectivesTo estimate the prevalence of obesity and overweight in children and adolescents in our city and to investigate the associated factors.Subjects and methodsA cross-sectional study of 1317 children and adolescents aged 2-16 years. Multistage probability sampling was used to select three groups of subjects: 411 aged 12 to 16 years, 504 aged 6 to 12 years, and 402 aged 2 to 6 years. Body mass index was calculated, and obesity and overweight were diagnosed using the threshold levels of the International Obesity Task Force for children and adolescents. Parents were asked about eating habits, health, social, and demographic aspects. Results are given as percentages (95% confidence interval). The relationship between obesity and overweight and the different variables was studied using multiple logistic regression. The adjusted odds ratio (OR) was calculated.ResultsAmong children and adolescentes aged 2-16 years, 9.5% (8.0%-11.0%) were obese and 22.4% (23.3%-24.6%) were overweight. Of subjects aged 12-16 years, 8.5% (5.9%-11.2%) were obese and 20.5% (16.7%-24.3%) were overweight. In the groups aged 6-12 years and 2-6 years, rates of obesity and overweight were 11.6% (8.9% -14.3%) and 31.0% (27.0-35.0) and 8.0% (5.4%-10.6%) and 13.6% (10.3%-16.9%) respectively. Obesity or overweight was associated to age (OR 1.21; P< 0.001), maternal obesity (OR 10.99; P= 0.008), a birthweight higher than 4 kg (OR 2.91; p 0.002), and formula feeding (OR 1.82; P= 0.005).ConclusionObesity and overweight in children and adolescents are highly prevalent problems in our city.     

Regeneration of Soft Tissues Is Promoted by MMP1 Treatment after Digit Amputation in Mice

The ratio of matrix metalloproteinases (MMPs) to the tissue inhibitors of metalloproteinases (TIMPs) in wounded tissues strictly control the protease activity of MMPs, and therefore regulate the progress of wound closure, tissue regeneration and scar formation. Some amphibians (i.e. axolotl/newt) demonstrate complete regeneration of missing or wounded digits and even limbs; MMPs play a critical role during amphibian regeneration. Conversely, mammalian wound healing re-establishes tissue integrity, but at the expense of scar tissue formation. The differences between amphibian regeneration and mammalian wound healing can be attributed to the greater ratio of MMPs to TIMPs in amphibian tissue. Previous studies have demonstrated the ability of MMP1 to effectively promote skeletal muscle regeneration by favoring extracellular matrix (ECM) remodeling to enhance cell proliferation and migration. In this study, MMP1 was administered to the digits amputated at the mid-second phalanx of adult mice to observe its effect on digit regeneration. Results indicated that the regeneration of soft tissue and the rate of wound closure were significantly improved by MMP1 administration, but the elongation of the skeletal tissue was insignificantly affected. During digit regeneration, more mutipotent progenitor cells, capillary vasculature and neuromuscular-related tissues were observed in MMP1 treated tissues; moreover, there was less fibrotic tissue formed in treated digits. In summary, MMP1 was found to be effective in promoting wound healing in amputated digits of adult mice.     

Locking the 150-Cavity Open: In Silico Design and Verification of Influenza Neuraminidase Inhibitors

Neuraminidase (NA) of influenza is a key target for virus infection control and the recently discovered open 150-cavity in group-1 NA provides new opportunity for novel inhibitors design. In this study, we used a combination of theoretical methods including fragment docking, molecular linking and molecular dynamics simulations to design ligands that specifically target at the 150-cavity. Through in silico screening of a fragment compound library on the open 150-cavity of NA, a few best scored fragment compounds were selected to link with Zanamivir, one NA-targeting drug. The resultant new ligands may bind both the active site and the 150-cavity of NA simultaneously. Extensive molecular dynamics simulations in explicit solvent were applied to validate the binding between NA and the designed ligands. Moreover, two control systems, a positive control using Zanamivir and a negative control using a low-affinity ligand 3-(p-tolyl) allyl-Neu5Ac2en (ETT, abbreviation reported in the PDB) found in a recent experimental work, were employed to calibrate the simulation method. During the simulations, ETT was observed to detach from NA, on the contrary, both Zanamivir and our designed ligand bind NA firmly. Our study provides a prospective way to design novel inhibitors for controlling the spread of influenza virus.     

Distinguishing the effects of vegetation restoration on runoff and sediment generation on simulated rainfall on the hillslopes of the loess plateau of China

Aims

Since the 1970s, extensive croplands were converted to forest and pasture lands to control severe soil erosion on the Loess Plateau of China. We quantify the direct and indirect effects of vegetation restoration on runoff and sediment yield on hillslopes in the field to improve environmental governance.

Methods

An artificial rainfall experiment at a rainfall intensity of 120 mm h⁻¹ and a slope gradient of 22° were used to distinguish the effects of vegetation restoration on runoff and sediment yield.

Results

Compared to the farmland slopes, vegetation restoration directly prolonged the time-to-runoff by 140%, reduced the runoff rate by 20%, and increased the soil infiltration capacity by 15%. Vegetation restoration indirectly delayed the time-to-runoff by 120%, reduced the runoff rate and sediment yield rate by 50% and 94%, respectively, and increased the soil infiltration capacity by 58% on the hillslopes with vegetation restoration.

Conclusions

The direct effects of vegetation restoration on runoff and sediment yield were lower than its indirect impacts. Vegetation cover, decreases in soil bulk density, and increases in belowground root biomasses and > 0.25 mm aggregate stability were the primary causes of runoff and sediment yield reduction on the slopes with vegetation restoration.

     

Arsenic,Cadmium and Lead Erythrocyte Concentrations in Men with a High,Moderate and Low Level of Physical Training

Biological Trace Element Research - The aim of the present study was to determine changes occurring in the erythrocyte concentrations of arsenic (As), cadmium (Cd) and lead (Pb) in highly trained...