Physiological Functions of Nedd4-2: Lessons from Knockout Mouse Models

Publication date: Available online 29 June 2018
Source:Trends in Biochemical Sciences
Author(s): Jantina A. Manning, Sharad Kumar
Protein modification by ubiquitination plays a key evolutionarily conserved role in regulating membrane proteins. Nedd4-2, a ubiquitin ligase, targets membrane proteins such as ion channels and transporters for ubiquitination. This Nedd4-2-mediated ubiquitination provides a crucial step in controlling the membrane availability of these proteins, thus affecting their signaling and physiological outcomes. In one well-studied example, Nedd4-2 fine-tunes the physiological function of the epithelial sodium channel (ENaC), thus modulating Na⁺ reabsorption by epithelia to maintain whole-body Na⁺ homeostasis. This review summarizes the key signaling pathways regulated by Nedd4-2 and the possible implications of such regulation in various pathologies.



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Quality Control in the Endoplasmic Reticulum: Crosstalk between ERAD and UPR pathways

Publication date: Available online 29 June 2018
Source:Trends in Biochemical Sciences
Author(s): Jiwon Hwang, Ling Qi
Endoplasmic reticulum (ER)-associated degradation (ERAD) and the unfolded protein response (UPR) are two key quality-control machineries in the cell. ERAD is responsible for the clearance of misfolded proteins in the ER for cytosolic proteasomal degradation, while UPR is activated in response to the accumulation of misfolded proteins. It has long been thought that ERAD is an integral part of UPR because expression of many ERAD genes is controlled by UPR; however, recent studies have suggested that ERAD has a direct role in controlling the protein turnover and abundance of IRE1α, the most conserved UPR sensor. Here, we review recent advances in our understanding of IRE1α activation and propose that UPR and ERAD engage in an intimate crosstalk to define folding capacity and maintain homeostasis in the ER.



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Ultrasensitive detection of trypsin activity and inhibitor screening based on the electron transfer between phosphorescence copper nanocluster and cytochrome c

Publication date: 1 November 2018
Source:Talanta, Volume 189
Author(s): Shiyu Zhang, Can Chen, Xiaofei Qin, Qianchen Zhang, Jinhua Liu, Jixin Zhu, Yongqian Gao, Lin Li, Wei Huang
Trypsin, as one of important proteases, is specific for catalyzing the hydrolysis of peptide and ester bonds containing lysine and arginine residues at the C-terminus. The level of trypsin in biological fluids can serve as a reliable and specific diagnostic biomarker for pancreatic function and its pathological changes. Herein, we demonstrate the application of phosphorescent Cu NCs for trypsin detection for the first time depending on the electron transfer between Cu NCs and cyt c. Cyt c and Cu NCs were selected as the quencher and the fluorophore, respectively. Cu NCs could bind to the positively charged cyt c through electrostatic and hydrophobic interactions, and the phosphorescence of Cu NCs was efficiently quenched by the metal-containing heme of cyt c. In the presence of trypsin, cyt c was digested, thus phosphorescence of Cu NCs remained. Therefore, a new and continuous phosphorescence assay for the detection of trypsin activity and its inhibitor screening was established. The plot of relative fluorescence versus trypsin concentration obtains a good linear detection range from 0 to 20 ng/mL (R² = 0.9657), and a detection limit of 2 ng/mL, which is much lower than 20 ng/mL of the sensor in buffer solution because of urine amplifying the phosphorescence signal of Cu NCs based on the FRET strategy. This assay still has been successfully applied to trypsin inhibitor screening, demonstrating its potential application in drug discovery.

Graphical abstract

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Mimicking peroxidase activity of Co2(OH)2CO3-CeO2 nanocomposite for smartphone based detection of tumor marker using paper-based microfluidic immunodevice

Publication date: 1 November 2018
Source:Talanta, Volume 189
Author(s): Negar Alizadeh, Abdollah Salimi, Rahman Hallaj
We present a paper-based microfluidic colorimetric immunosensor for the detection of carcinoembryonic antigen (CEA), using Co2(OH)2CO3-CeO2 nanocomposite with extraordinary intrinsic peroxidase like activity. The morphology and composition of the nanocomposite characterized with Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques. The proposed immunosensor facilely fabricated by loading mixture of ionic liquid and chitosan functionalized primary antibodies (Ab1) on the surface of paper. Compared to traditional paper based immunodevice, when ionic liquid was used the nonspecific binding protein from the paper surface was more effectively removed. Secondary antibodies (Ab2) were stacked on the surface of the carboxylated Co2(OH)2CO3-CeO2 nanocomposite. The immunosensor response was obtained by a color change resulting from Co2(OH)2CO3-CeO2 nanocomposite catalyzing the oxidation of 3,3′,5,5′-tetramethyl benzidine in the presence of H2O2. The colorimetric sensing was accomplished on the paper, using smartphone for taking a photo and then analyzing the colors with an installed application. Detection of CEA was performed by this method with a linear range from 0.002 to 75.0 ng mL⁻¹ and a detection limit of 0.51 pg mL⁻¹. In this paper we developed simple, cost-effective and portable design for sensitive immunoassay and point-of-care diagnostics of cancer marker.

Graphical abstract

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Bioluminescent SNP genotyping technique: Development and application for detection of melanocortin 1 receptor gene polymorphisms

Publication date: 1 November 2018
Source:Talanta, Volume 189
Author(s): Eugenia E. Bashmakova, Vasilisa V. Krasitskaya, Alexander A. Bondar, Ekaterina N. Eremina, Eugene V. Slepov, Ruslan A. Zukov, Ludmila A. Frank
SNP genotyping based on the reaction of specific primer extension with the following bioluminescent detection of its products was shown to be potentially applicable for biomedical exploration. The paper describes its elaboration and first application in extensive biomedical research concerning MC1R gene variants' frequency and associations with clinical characteristics in melanoma patients of Eastern Siberia (Krasnoyarsk region, Russia). Polymorphisms rs 1805007 (R151C), rs 1805008 (R160W), and rs 1805009 (D294H) were detected in 174 DNA samples from patients with histologically proved diagnosis of cutaneous melanoma and in 200 samples from healthy individuals. All the results on bioluminescent SNP genotyping were confirmed by Sanger sequencing. Some features characteristic of the population were found, i.e. melanoma is mostly associated with R160W or R151C while variant D294H is extremely rare; simultaneous carriage of any two investigated variants is also strongly associated with melanoma; R151C is associated with ulceration and consequently the disease course is more aggressive, etc.The design of the technique allows fast evaluation of any known diagnostically important SNP frequencies and associations across population.

Graphical abstract

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A novel air-assisted liquid-liquid microextraction based on in-situ phase separation for the HPLC determination of bisphenols migration from disposable lunch boxes to contacting water

Publication date: 1 November 2018
Source:Talanta, Volume 189
Author(s): Qinghua Zhou, Zanhui Jin, Jia Li, Bin Wang, Xiuzhen Wei, Jinyuan Chen
In this study, a novel air-assisted liquid-liquid microextraction (AALLME) method was developed for the HPLC determination of bisphenols migration from disposable plastic lunch box to contacting water. The AALLME was carried out in commercially-available medical plastic syringes with low-density extraction solvent (n-octanol), and the reaction of NaHCO3 and HCl was introduced to simultaneously induce the in-situ phase separation and salt effect. After the AALLME processes, the upper organic phase was pushed into the end of syringes (narrow tube) by moving the piston so that it could be readily collected for the HPLC analysis. The factors including the type and volume of extraction solvent, NaHCO3 addition and extraction cycles were optimized. Under the optimal conditions, the limits of detection (LODs) for target bisphenols were evaluated to be 0.2–0.7 μg L⁻¹, and good linearities with correlation coefficients higher than 0.9955 were obtained. The recoveries for target bisphenols ranged from 80% to 106%, with the relative standard deviations (RSDs) of 4.4–14.1%. The proposed method was successfully applied to investigate the migration of bisphenols from the disposable plastic lunch boxes to the contacting water, revealing that compared to the conventional water-bath heating, the microwave heating could induce the significant migration of bisphenols in a much shorter time.

Graphical abstract

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Increasing the structural energy dissipation of laminated fibre composite materials by delamination control

Publication date: 15 October 2018
Source:Materials & Design, Volume 156
Author(s): M. Kuhtz, A. Hornig, J. Richter, M. Gude
In this paper an approach to increase the energy absorption capacity of laminated composites is investigated. The interlaminar interfaces of two different composite materials, a 2/2 twill weave of glass fibre reinforced polypropylene and a plain weave of carbon reinforced epoxy, are modified. Perforated, non adhesive polytetrafluorethylene (PTFE-) foils were interleaved between the composite layers leading to different interlaminar contact area (ICA) set-ups. The energy absorption capacity, impact resistance as well as the damage and failure behaviour, especially delamination, are evaluated in Charpy drop weight experiments. Based on the resulting force-displacement-response, initiation and propagation energies as well as the ductility index are evaluated. High speed camera imaging is used to correlate failure phenomena to structural response. It can be shown, that the failure behaviour of textile reinforced composites is significantly influenced by the interface modification concept. As a result, the delamination initiation and propagation is enhanced with lower ICA leading to higher energy absorption capacity on the one hand and higher propagation-to-initiation-energy-ratio on the other hand. Consequently, the already high energy absorption capacity of composite materials can be further increased up to 65% while the ductility index rises up to ten times.

Graphical abstract

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