SUMOylation mediates CtIP’s functions in DNA end resection and replication fork protection

Double-strand breaks and stalled replication forks are a significant threat to genomic stability that can lead to chromosomal rearrangements or cell death. The protein CtIP promotes DNA end resection, an early step in homologous recombination repair, and has been found to protect perturbed forks from excessive nucleolytic degradation. However, it remains unknown how CtIP’s function in fork protection is regulated. Here, we show that CtIP recruitment to sites of DNA damage and replication stress is impaired upon global inhibition of SUMOylation. We demonstrate that CtIP is a target for modification by SUMO-2 and that this occurs constitutively during S phase. The modification is dependent on the activities of cyclin-dependent kinases and the PI-3-kinase-related kinase ATR on CtIP’s carboxyl-terminal region, an interaction with the replication factor PCNA, and the E3 SUMO ligase PIAS4. We also identify residue K578 as a key residue that contributes to CtIP SUMOylation. Functionally, a CtIP mutant where K578 is substituted with a non-SUMOylatable arginine residue is defective in promoting DNA end resection, homologous recombination, and in protecting stalled replication forks from excessive nucleolytic degradation. Our results shed further light on the tightly coordinated regulation of CtIP by SUMOylation in the maintenance of genome stability.     

DARPin Ec1-LMWP protein scaffold in targeted delivery of siRNA molecules through EpCAM cancer stem cell marker

Molecular Biology Reports - This study is to investigate the binding ability of Designed Ankyrin Repeat Proteins type Ec1that was fused to Low Molecular Weight Protamine (DARPin Ec1-LMWP) protein...     

Application of zinc oxide and sodium alginate for biofouling mitigation in a membrane bioreactor treating urban wastewater

Abstract

This research aimed to mitigate fouling in membrane bioreactors (MBR) through concurrent usage of zinc oxide as an antibacterial agent (A) and sodium alginate as a hydrophilic agent (H) within a polyacrylonitrile membrane (PM) structure. The antibacterial polymeric membranes (APM) and antibacterial hydrophilic polymeric membranes (AHPM) synthesized showed a higher porosity, mechanical strength and bacterial inhibition zone, and a lower contact angle in comparison with PM membranes. EDS, SEM and AFM analyses were used to characterize the chemical, structural, and morphological properties of PM, APM, and AHPM. The flux of PM, APM, and AHPM in MBR was 37, 48, and 51?l m^?2 h^?1 and COD removal was 81, 93.5, and 96.7%, respectively. After MBR operation for 35?days in an urban wastewater treatment, only 50% of the flux of PM was recovered, while the antibacterial and hydrophilic agents yielded a flux recovery of 72.7 and 100% for APM and AHPM, respectively.     

Concomitant Up-Regulation of Hsa- Mir-374 and Down-Regulation of Its Targets,GSK-3β and APC,in Tissue Samples of Colorectal Cancer

Background:The WNT-pathway is involved in several cancers, including colorectal cancer (CRC). Many cell signaling components and pathways are controlled by microRNAs. The main purpose of the present study was to investigate the expression of hsa-miR-374, and its two target genes of the Wnt-pathway in CRC clinical samples.Methods:In this study, we predicted the miRNAs targeting key genes of WNT-pathway using bioinformatics algorithms. The expression levels of hsa-miR-374, APC and GSK-3β on 48 pairs of Formalin-Fixed Paraffin-Embedded (FFPE) CRC tumors and marginal-tumors were evaluated using real time-PCR. Additionally, the hsa-miR-374a-5p precursor sequence was amplified by whole-blood DNA as a template. This amplicon was cloned into pEGFP-c1 expression vector and transfected into SW742 cells. Aside from this, MTT assay was performed to evaluate the effect of miR-374 on cell viability. Results:The bioinformatics analysis indicated that hsa-miR-374 binds to the regulatory region the key components of WNT-pathway, including APC and GSK-3β considering the recognition elements and mirSVR scores. Our results revealed significant down-regulation of GSK-3β (0.94 times, p= 0.0098) and APC (0.96 times, p= 0.03) and up-regulation of miR-374 (1.22 times, p= 0.0071) on tumor samples compared with their normal pairs. Meanwhile, the results of the over-expression of miR-374 showed down-regulation of APC and GSK-3β. MTT-assay also indicated that the miR-374 increased cell survival.Conclusion:The results of our study indicated a concomitant change in the expression of miR-374 and its two related target genes, in clinical samples of CRC. Hsa-miR-374 might be as a helpful biomarker or therapeutic target in CRC.Key Words: Colorectal cancer, GSK-3β, miR-374, WNT     

A bioinspired 3D shape olibanum-collagen-gelatin scaffolds with tunable porous microstructure for efficient neural tissue regeneration

There are a number of procedures for regeneration of injured nerves; however, tissue engineering scaffolds seems to be a promising approach for recovery of the functionality of the injured nerves. Consequently, in this study, olibanum-collagen-gelatin scaffolds were fabricated by freeze-cast technology. For this purpose, the olibanum and collagen were extracted from natural sources. The effect of solidification gradient on microstructure and properties of scaffolds was investigated. Scanning electron microscopy micrographs showed the formation of lamellar-type microstructure in which the average pore size reduced with an increase in freezing rate. According to the results, the prepared scaffolds at lower freezing rate showed a slight reduction in mechanical strength while the swelling and biodegradation ratio were increased due to the presence of larger pores and unidirectional channels. The composition of scaffolds and oriented microstructure improved cellular interaction. In addition, scaffolds with lower freezing rate exhibited promising results in terms of adhesion, spreading, and proliferation. In brief, the synthesized scaffolds at lower solidification rate have the potential for more in vitro and in vivo analyses to regeneration of neural defects.     

HER-2-based design of pertuzumab mimetic peptides

An in silico peptide design strategy is conducted in order to introduce a novel series of pertuzumab mimetic peptides, aimed to target the extracellular domain of HER-2 and prevent its signal transduction. A combination of alanine scanning and contact surface analysis is employed to assess the pertuzumab paratope, HER-2 epitope and their hot spots. Furthermore, the recognised residues are utilised to construct nine 10-mer peptides. Some of the peptides are modified pertuzumab paratope sequences, whereas the others are designed and modified as strongly binding complementary peptides for HER-2 epitope. Evaluation of the peptides is carried out through homology modelling, molecular dynamics simulation (MDS) and docking. It was revealed that all peptides mimic pertuzumab performance since they exhibit noticeable binding interaction energies, inhibitory efficiencies and number of hot spots. However, YNDSTHGERL with five hot spots and considerable interaction energy has the highest ability in interfering with HER-2-specific epitope. Inhibiting potency of this peptide is verified through MDSs.     

The influence of drinking-water pollution with heavy metal on the expression of IL-4 and IFN-γ in mice by real-time polymerase chain reaction

In recent years, water pollution has been converted to a challenging discussion in health area of human being. Heavy elements are one of the most important water pollutants and their negative adverse effects on body systems have been confirmed. In this study, investigation of effects of two heavy elements including lead (Pb) and copper (Cu) on expression of interlukin-4 (IL-4) and interferon-gamma (IFN-γ) as humoral and cellular immunity biomarkers, respectively, was aimed and PCR, real-time PCR and electrophoresis techniques were used. In this study, BALB/c mice were studied that had free access to drinking water which contained Cu or Pb salts. After 2 weeks, spleens of mice were removed, RNA extracted, and cDNA was prepared for RT-PCR. Then the expression of IL-4 and IFN-γ genes were assessed by real-time PCR. The expression of IFN-γ was up-regulated in both treated groups and the expression of IL-4 was only up-regulated in the group treated with Cu and down-regulated in the group treated with Pb. This study shows that the presence of heavy elements as drinking-water pollutants results in a disproportion of natural cytokines balances, and thus may result in a negative effect on immune system.