scholarly journals Exploring the role of the various methionine residues in the Escherichia coli CusB adapter protein

2019 ◽  
Author(s):  
Aviv Meir ◽  
Gulshan Walke ◽  
Fabian Schwerdtfeger ◽  
Lada Gevorkyan-Airapetov ◽  
Sharon Ruthstein
Keyword(s):  
Conformational Changes ◽  
Underlying Mechanism ◽  
Modern Medicine ◽  
Proper Function ◽  
Adapter Protein ◽  
Novel Drugs ◽  
Regulation Network ◽  
Methionine Residues

AbstractThe dissemination of resistant pathogenic microbes has become one of the most challenging problems that modern medicine has faced. Developing novel drugs based on new molecular targets that previously were not targeted, is therefore the highest priority in antibiotics research. One approach that has been recently suggested is to inhibit copper transporters in prokaryotic systems. Copper is required for many biological pathways, but sometimes it can harm the cell. Pathogenic systems have a highly sophisticated copper-regulation network; therefore, a better understanding of how this network operates at the molecular level should assist in developing the next generation of antibiotics. The CusB protein is part of the CusCBA periplasmic Cu(I) efflux system in Gram-negative bacteria, and it was recently reported to play a key role in the functioning of the whole CusCBA system, in which conformational changes as well as the assembly/disassembly process control the opening of the transporter. More knowledge of the underlying mechanism is needed to attain a full understanding of CusB functioning, which is associated with targeting specific and crucial residues in CusB. Here, we combine in-vitro structural measurements, which used EPR spectroscopy and UV-Vis measurements, with cell experiments to explore the role of the various methionine residues in CusB. We targeted two methionine residues (M227 and M241) that are essential for the proper function of CusB.

scholarly journals Kindlin-2 mediates mechanotransduction in bone by regulating expression of Sclerostin in osteocytes

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Lei Qin ◽  
Xuekun Fu ◽  
Jing Ma ◽  
Manxia Lin ◽  
Peijun Zhang ◽  
...  
Keyword(s):  
Bone Loss ◽  
Mechanical Stimulation ◽  
Fluid Shear Stress ◽  
Weight Bearing ◽  
Underlying Mechanism ◽  
Long Bones ◽  
Cell Orientation ◽  
Cytoskeleton Organization

AbstractOsteocytes act as mechanosensors in bone; however, the underlying mechanism remains poorly understood. Here we report that deleting Kindlin-2 in osteocytes causes severe osteopenia and mechanical property defects in weight-bearing long bones, but not in non-weight-bearing calvariae. Kindlin-2 loss in osteocytes impairs skeletal responses to mechanical stimulation in long bones. Control and cKO mice display similar bone loss induced by unloading. However, unlike control mice, cKO mice fail to restore lost bone after reloading. Osteocyte Kindlin-2 deletion impairs focal adhesion (FA) formation, cytoskeleton organization and cell orientation in vitro and in bone. Fluid shear stress dose-dependently increases Kindlin-2 expression and decreases that of Sclerostin by downregulating Smad2/3 in osteocytes; this latter response is abolished by Kindlin-2 ablation. Kindlin-2-deficient osteocytes express abundant Sclerostin, contributing to bone loss in cKO mice. Collectively, we demonstrate an indispensable novel role of Kindlin-2 in maintaining skeletal responses to mechanical stimulation by inhibiting Sclerostin expression during osteocyte mechanotransduction.

scholarly journals Obesity-Induced Methylation of Osteopontin Contributes to Adipogenic Differentiation of Adipose-Derived Mesenchymal Stem Cells

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Min Tang ◽  
Rui Chen ◽  
Hao Wang ◽  
Guowei Sun ◽  
Fan Yin ◽  
...  
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Adipogenic Differentiation ◽  
Underlying Mechanism ◽  
Human Beings ◽  
Fatty Livers ◽  
Novel Target ◽  
Adipose Mass

Obesity is a major risk factor for many chronic diseases, including diabetes, fatty livers, and cancer. Expansion of the adipose mass has been shown to be related to adipogenic differentiation of adipose-derived mesenchymal stem cells (ASCs). However, the underlying mechanism of this effect has yet to be elucidated. We found that osteopontin (OPN) is downregulated in ASCs and adipose tissues of obese mice and overweight human beings because of methylation on its promoter, indicating that OPN may affect the development of obesity. Silencing of OPN in wild-type ASCs promotes adipogenic differentiation, while reexpression of OPN reduced adipogenic differentiation in OPN−/− ASCs. The role of extracellular OPN in ASC differentiation was further demonstrated by supplementation and neutralization of OPN. Additionally, OPN suppresses adipogenic differentiation in ASCs through the C/EBP pathways. Consistent with these in vitro results, by intravenous injection of OPN-expressing adenovirus to the mice, we found OPN can delay the development of obesity and improve insulin sensitivity. Therefore, our study demonstrates an important role of OPN in regulating the development of obesity, indicating OPN might be a novel target to attenuate obesity and its complications.

scholarly journals Overview of RNA G-quadruplex structures

2017 ◽  
Vol 63 (4) ◽  
Author(s):  
Magdalena Małgowska
Keyword(s):  
Three Dimensional ◽  
Telomere Maintenance ◽  
Structural Studies ◽  
Biological Functions ◽  
Cellular Processes ◽  
Novel Drugs ◽  
G Quadruplex ◽  
Conformational Diversity

G-quadruplexes are non-canonical secondary structures which may be formed by guanine rich sequences, both in vitro and in living cells. The number of biological functions assigned to these structural motifs has grown rapidly since the discovery of their involvement in the telomere maintenance. Knowledge of the three-dimensional structures of G-quadruplexes plays an important role in understanding their conformational diversity, physiological functions, and in the design of novel drugs targeting G-quadruplexes. For the last decades, structural studies have been mainly focused on the DNA G-quadruplexes. Their RNA counterparts gained an increased interest along with still-emerging recognition of the central role of RNA in multiple cellular processes. In this review we focus on structural properties of RNA G-quadruplexes, based on high-resolution structures, available in RCSB PDB data base and on structural models. In addition, we point out to the current challenges in this field of research.

Potential role of multiple members of the kallikrein-related peptidase family of serine proteases in activating latent TGFβ1 in semen

2010 ◽  
Vol 391 (1) ◽  
Author(s):  
Nashmil Emami ◽  
Eleftherios P. Diamandis
Keyword(s):  
Conformational Changes ◽  
Seminal Plasma ◽  
Serine Proteases ◽  
Transforming Growth Factor ◽  
Ex Vivo ◽  
Transforming Growth Factor Β1 ◽  
Peptide Fragments ◽  
Biochemical Mechanisms

Abstract Transforming growth factor β1 (TGFβ1) has been implicated as a key contributor of immunosuppression in seminal plasma. The biochemical mechanisms that lead to production of active seminal TGFβ1 are not fully understood. It is plausible that TGFβ1 activation is partly induced simultaneously with the release of motile spermatozoa following liquefaction of the semen coagulum. Several members of the kallikrein-related peptidase (KLK) family are involved in the regulation of semen liquefaction. This study examines the involvement of these KLKs in TGFβ1 activation in vitro and ex vivo, in seminal plasma. Latent TGFβ1 was rapidly activated by KLK14. The latency-associated propeptide (LAP) was shown to be cleaved by KLK14 into small peptide fragments, providing a possible mechanism for TGFβ1 activation. KLK14 also cleaved the latent TGFβ binding protein 1 (LTBP1). KLK1, 2, and 5 might also contribute to TGFβ1 activation by nicking the LAP motif and inducing conformational changes that aid in subsequent processing of LAP or through LTBP1 cleavage. Our study provides strong evidence for the involvement of multiple members of the seminal KLK cascade in activation of latent TGFβ1 in seminal plasma. These findings might have clinical implications in infertility treatment of cases with concurrent delayed liquefaction and TGFβ1-related semen antigenicity.

scholarly journals Citrulline directly modulates muscle protein synthesis via the PI3K/MAPK/4E-BP1 pathway in a malnourished state: evidence from in vivo, ex vivo, and in vitro studies

2017 ◽  
Vol 312 (1) ◽  
pp. E27-E36 ◽  
Author(s):  
Servane Le Plénier ◽  
Arthur Goron ◽  
Athanassia Sotiropoulos ◽  
Eliane Archambault ◽  
Chantal Guihenneuc ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Ex Vivo ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Fold Increase ◽  
Underlying Mechanism ◽  
Muscle Homeostasis

Citrulline (CIT) is an endogenous amino acid produced by the intestine. Recent literature has consistently shown CIT to be an activator of muscle protein synthesis (MPS). However, the underlying mechanism is still unknown. Our working hypothesis was that CIT might regulate muscle homeostasis directly through the mTORC1/PI3K/MAPK pathways. Because CIT undergoes both interorgan and intraorgan trafficking and metabolism, we combined three approaches: in vivo, ex vivo, and in vitro. Using a model of malnourished aged rats, CIT supplementation activated the phosphorylation of S6K1 and 4E-BP1 in muscle. Interestingly, the increase in S6K1 phosphorylation was positively correlated ( P < 0.05) with plasma CIT concentration. In a model of isolated incubated skeletal muscle from malnourished rats, CIT enhanced MPS (from 30 to 80% CIT vs. Ctrl, P < 0.05), and the CIT effect was abolished in the presence of wortmannin, rapamycin, and PD-98059. In vitro, on myotubes in culture, CIT led to a 2.5-fold increase in S6K1 phosphorylation and a 1.5-fold increase in 4E-BP1 phosphorylation. Both rapamycin and PD-98059 inhibited the CIT effect on S6K1, whereas only LY-294002 inhibited the CIT effect on both S6K1 and 4E-BP1. These findings show that CIT is a signaling agent for muscle homeostasis, suggesting a new role of the intestine in muscle mass control.

EDD1 predicts prognosis and regulates gastric cancer growth in vitro and in vivo via miR-22

2016 ◽  
Vol 0 (0) ◽  
Author(s):  
Min Yang ◽  
Nan Jiang ◽  
Qi-wei Cao ◽  
Qing Sun
Keyword(s):  
Gastric Cancer ◽  
Cancer Cells ◽  
Cancer Progression ◽  
Patient Survival ◽  
Underlying Mechanism ◽  
Gastric Cancer Cells ◽  
Cancer Tissues

Abstract Gastric cancer is the most common digestive malignant tumor worldwild. EDD1 was reported to be frequently amplified in several tumors and played an important role in the tumorigenesis process. However, the biological role and potential mechanism of EDD1 in gastric cancer remains poorly understood. In this study, we are aim to investigate the effect of EDD1 on gastric cancer progression and to explore the underlying mechanism. The results showed the significant up-regulation of EDD1 in -gastric cancer cell tissues and lines. The expression level of EDD1 was also positively associated with advanced clinical stages and predicted poor overall patient survival and poor disease-free patient survival. Besides, EDD1 knockdown markedly inhibited cell viability, colony formation, and suppressed tumor growth. Opposite results were obtained in gastric cancer cells with EDD1 overexpression. EDD1 knockdown was also found to induce gastric cancer cells apoptosis. Further investigation indicated that the oncogenic role of EDD1 in regulating gastric cancer cells growth and apoptosis was related to its PABC domain and directly through targeting miR-22, which was significantly down-regulated in gastric cancer tissues. Totally, our study suggests that EDD1 plays an oncogenic role in gastric cancer and may be a potential therapeutic target for gastric cancer.

Therapeutics and Research Related to Glioblastoma: Advancements and Future Targets

2020 ◽  
Vol 21 (3) ◽  
pp. 186-198 ◽  
Author(s):  
Vishal Chavda ◽  
Vimal Patel ◽  
Dhananjay Yadav ◽  
Jigar Shah ◽  
Snehal Patel ◽  
...  
Keyword(s):  
Treatment Options ◽  
Graphene Quantum Dots ◽  
Primary Brain Tumor ◽  
In Vitro Models ◽  
Molecular Pathways ◽  
Dismal Prognosis ◽  
Novel Drugs

Glioblastoma, the most common primary brain tumor, has been recognized as one of the most lethal and fatal human tumors. It has a dismal prognosis, and survival after diagnosis is less than 15 months. Surgery and radiotherapy are the only available treatment options at present. However, numerous approaches have been made to upgrade in vivo and in vitro models with the primary goal of assessing abnormal molecular pathways that would be suitable targets for novel therapeutic approaches. Novel drugs, delivery systems, and immunotherapy strategies to establish new multimodal therapies that target the molecular pathways involved in tumor initiation and progression in glioblastoma are being studied. The goal of this review was to describe the pathophysiology, neurodegeneration mechanisms, signaling pathways, and future therapeutic targets associated with glioblastomas. The key features have been detailed to provide an up-to-date summary of the advancement required in current diagnosis and therapeutics for glioblastoma. The role of nanoparticulate system graphene quantum dots as suitable therapy for glioblastoma has also been discussed.

Enhanced β-Catenin/Foxo1 Activity Alleviates Pulmonary Fibrosis by Inhibiting β-Catenin/T Cell Factor Signaling

2020 ◽  
Vol 10 (2) ◽  
pp. 182-188
Author(s):  
Kun Gui ◽  
Yu Huang ◽  
Meijin Wang ◽  
Jun Yang
Keyword(s):  
Extracellular Matrix ◽  
Pulmonary Fibrosis ◽  
Inflammatory Cytokines ◽  
Underlying Mechanism ◽  
Control Group ◽  
Kidney Fibrosis ◽  
Mrc5 Cell

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive fibrosing interstitial pneumonia, resulting in chronic respiratoryfailure and eventually death. β-catenin/Foxo1 showed a protective property in kidney fibrosis, but the role of β-catenin/Foxo1 in IPF was unclear. Our study aimed to investigate the role of β-catenin/Foxo1 in IPF and explore its underlying mechanism. The IPF model was established by injection of bleomycin (BLM) in vivo and stimulation by TGF-β1 in MRC5 cell in vitro. Haematoxylin-eosin staining and Masson’s trichrome staining were performed to examine histopathological injury in lung. Protein expression of corresponding genes was detected using western blot. Immunofluorescence staining assay was carried out to detect the expression of β-catenin, Foxo1, TCF and α-SMA. The expression levels of inflammatory cytokines were determined using ELISA kit assay. The results showed that BLM induced a serious pulmonary injury and proliferated fibroblasts. A higher interaction of β-catenin with TCF and a lower interaction of β-catenin with Foxo1 was found in BLM group compared to the control group. TGF-β1 promoted β-catenin/TCF, whereas ICG-001 inhibited β-catenin/TCF, and promoted β-catenin/Foxo1. Furthermore, ICG-001 reversed TGF-β1 induced largely production of inflammatory cytokines and accumulation of extracellular matrix, as well as high expression of α-SMA. However, AS1842856, a FOXO1 antagonist, strengthened the effects induced by TGF-β1. In summary, our study revealed that β-catenin/Foxo1 protected against IPF through inhibiting inflammatory response and extracellular matrix accumulation, providing an alternative approach to explain the potential mechanism of IPF and seek for more effective therapeutic drugs.

scholarly journals Irisin alleviates obesity-related spermatogenesis dysfunction via the regulation of the AMPKα signalling pathway

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Yang Mu ◽  
Huang-Guan Dai ◽  
Ling-Bo Luo ◽  
Jing Yang
Keyword(s):  
Oxidative Stress ◽  
Sperm Count ◽  
Underlying Mechanism ◽  
Signalling Pathway ◽  
Protective Effects ◽  
Exercise Induced ◽  
Amp Activated Protein Kinase

Abstract Background Infertility is a common complication in obese men. Oxidative stress and testicular apoptosis play critical roles in obesity-induced spermatogenesis dysfunction. It has been reported that irisin, an exercise-induced myokine, may attenuate oxidative damage and testicular apoptosis in several diseases; however, its role in obesity-induced spermatogenesis dysfunction remains unclear. The purpose of this study was to investigate the role and underlying mechanism of irisin in obesity-induced dysfunction of spermatogenesis. Methods Male mice were fed a high-fat diet (HFD) for 24 weeks to establish a model of obesity-induced spermatogenesis dysfunction. To explore the effects of irisin, mice were subcutaneously infused with recombinant irisin for 8 weeks beginning at 16 weeks after starting a HFD. To confirm the role of AMP-activated protein kinase α (AMPKα), AMPKα-deficient mice were used. Results The data showed decreased serum irisin levels in obese patients, which was negatively correlated with sperm count and progressive motility. Irisin was downregulated in the plasma and testes of obese mice. Supplementation with irisin protected against HFD-induced spermatogenesis dysfunction and increased testosterone levels in mice. HFD-induced oxidative stress, endoplasmic reticulum (ER) stress and testicular apoptosis were largely attenuated by irisin treatment. Mechanistically, we identified that irisin activated the AMPKα signalling pathway. With AMPKα depletion, we found that the protective effects of irisin on spermatogenesis dysfunction were abolished in vivo and in vitro. Conclusions In conclusion, we found that irisin alleviated obesity-related spermatogenesis dysfunction via activation of the AMPKα signalling pathway. Based on these findings, we hypothesized that irisin is a potential therapeutic agent against obesity-related spermatogenesis dysfunction.

scholarly journals Phosphorylation and O-GlcNAcylation of the PHF-1 Epitope of Tau Protein Induce Local Conformational Changes of the C-Terminus and Modulate Tau Self-Assembly Into Fibrillar Aggregates

2021 ◽  
Vol 14 ◽  
Author(s):  
François-Xavier Cantrelle ◽  
Anne Loyens ◽  
Xavier Trivelli ◽  
Oliver Reimann ◽  
Clément Despres ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Tau Protein ◽  
Posttranslational Modifications ◽  
Self Assembly ◽  
Critical Role ◽  
Small Peptides ◽  
C Terminus ◽  
The Impact

Phosphorylation of the neuronal microtubule-associated Tau protein plays a critical role in the aggregation process leading to the formation of insoluble intraneuronal fibrils within Alzheimer’s disease (AD) brains. In recent years, other posttranslational modifications (PTMs) have been highlighted in the regulation of Tau (dys)functions. Among these PTMs, the O-β-linked N-acetylglucosaminylation (O-GlcNAcylation) modulates Tau phosphorylation and aggregation. We here focus on the role of the PHF-1 phospho-epitope of Tau C-terminal domain that is hyperphosphorylated in AD (at pS396/pS404) and encompasses S400 as the major O-GlcNAc site of Tau while two additional O-GlcNAc sites were found in the extreme C-terminus at S412 and S413. Using high resolution NMR spectroscopy, we showed that the O-GlcNAc glycosylation reduces phosphorylation of PHF-1 epitope by GSK3β alone or after priming by CDK2/cyclin A. Furthermore, investigations of the impact of PTMs on local conformation performed in small peptides highlight the role of S404 phosphorylation in inducing helical propensity in the region downstream pS404 that is exacerbated by other phosphorylations of PHF-1 epitope at S396 and S400, or O-GlcNAcylation of S400. Finally, the role of phosphorylation and O-GlcNAcylation of PHF-1 epitope was probed in in-vitro fibrillization assays in which O-GlcNAcylation slows down the rate of fibrillar assembly while GSK3β phosphorylation stimulates aggregation counteracting the effect of glycosylation.

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