Cell Surface Receptor Protein Research Articles

Overview of Bacterial Protein Toxins from Pathogenic Bacteria: Mode of Action and Insights into Evolution.

Bacterial protein toxins are secreted by certain bacteria and are responsible for mild to severe diseases in humans and animals. They are among the most potent molecules known, which are active at very low concentrations. Bacterial protein toxins exhibit a wide diversity based on size, structure, and mode of action. Upon recognition of a cell surface receptor (protein, glycoprotein, and glycolipid), they are active either at the cell surface (signal transduction, membrane damage by pore formation, or hydrolysis of membrane compound(s)) or intracellularly. Various bacterial protein toxins have the ability to enter cells, most often using an endocytosis mechanism, and to deliver the effector domain into the cytosol, where it interacts with an intracellular target(s). According to the nature of the intracellular target(s) and type of modification, various cellular effects are induced (cell death, homeostasis modification, cytoskeleton alteration, blockade of exocytosis, etc.). The various modes of action of bacterial protein toxins are illustrated with representative examples. Insights in toxin evolution are discussed.

Abstract LB224: Neoplastic immune mimicry potentiates breast cancer progression

Abstract Dedifferentiation programs are commonly enacted during breast cancer progression where they enable novel cellular phenotypes. Increased cellular plasticity within the neoplastic compartment of tumors correlates with disease aggressiveness, often manifesting as greater resistance to cytotoxic therapies or increased ability to metastasize to distant organs. Here we report that subpopulations of ostensibly stem-like neoplastic breast epithelial cells express canonical leukocyte cell surface receptor proteins, and have named this unique cellular program ‘immune mimicry’ (IM). We have documented neoplastic cells engaging in IM by examination of histopathological breast tumor specimens and their derived cell lines, public human breast tumor single-cell RNA-seq datasets, and in murine transgenic and cell line-derived mammary cancer models. Immune-mimicked neoplastic cells harbor hallmarks of dedifferentiation and appear enriched for developing aggressive and high-grade tumors. Experimental studies with breast cancer cell lines revealed that neoplastic cells expressing leukocyte surface features are elicited by growth-arresting conditions, such as conventional cytotoxic chemotherapeutic treatments and during metastatic dissemination in mice. In addition, using proof-of-concept studies, we leveraged the canonical leukocyte activation marker CD69, to demonstrate how its expression by neoplastic epithelial cells confers a proliferative advantage under low-density conditions. We conclude that neoplastic breast epithelial cells expressing leukocyte surface receptors may signify a particularly malignant and tumor-initiating cell state. Moving forward, neoplastic IM will be evaluated for prognostic utility in breast cancer to determine whether this unique cell state stratifies patients with increased risks for tumor recurrence and metastasis. The authors acknowledge NIH/NCI (K00 CA212132, T32 CA254888, P30 CA069533), the Collins Medical Trust, the Susan G Komen Foundation, and the National Foundation for Cancer Research for funding. Citation Format: Eric B. Berens, Sokchea Khou, Elaine Huang, Amber Hoffman, Briana Johnson, Zena Werb, Laura M. Heiser, Lisa M. Coussens. Neoplastic immune mimicry potentiates breast cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB224.

Complement receptor 1 is the human erythrocyte receptor for Plasmodium vivax erythrocyte binding protein

The discovery that Africans were resistant to infection by Plasmodium vivax (P. vivax) led to the conclusion that P. vivax invasion relied on the P. vivax Duffy Binding Protein (PvDBP) interacting with the Duffy Antigen Receptor for Chemokines (DARC) expressed on erythrocytes. However, the recent reporting of P. vivax infections in DARC-negative Africans suggests that the parasite might use an alternate invasion pathway to infect DARC-negative reticulocytes. To identify the parasite ligands and erythrocyte receptors that enable P. vivax invasion of both DARC-positive and -negative erythrocytes, we expressed region II containing the Duffy Binding-Like (DBL) domain of P. vivax erythrocyte binding protein (PvEBP-RII) and verified that the DBL domain binds to both DARC-positive and -negative erythrocytes. Furthermore, an AVidity-based EXtracelluar Interaction Screening (AVEXIS) was used to identify the receptor for PvEBP among over 750 human cell surface receptor proteins, and this approach identified only Complement Receptor 1 (CR1, CD35, or C3b/C4b receptor) as a PvEBP receptor. CR1 is a well-known receptor for P. falciparum Reticulocyte binding protein Homology 4 (PfRh4) and is present on the surfaces of both reticulocytes and normocytes, but its expression decreases as erythrocytes age. Indeed, PvEBP-RII bound to a subpopulation of both reticulocytes and normocytes, and this binding was blocked by the addition of soluble CR1 recombinant protein, indicating that CR1 is the receptor of PvEBP. In addition, we found that the Long Homology Repeat A (LHR-A) subdomain of CR1 is the only subdomain responsible for mediating the interaction with PvEBP-RII.

Single-cell transcriptomics of peripheral blood mononuclear cells indicates impaired immune and inflammatory responses in alcohol-associated hepatitis

Alcohol-associated hepatitis (AH) is often diagnosed at advanced stages, and severe AH usually carries poor prognosis and high short-term mortality. In addition, it is challenging to understand the molecular mechanisms of immune dysregulation and inflammation in AH due to the cellular complexity and heterogeneity. Using single-cell RNA sequencing, previous studies found that AH causes dysfunctional innate immune response in monocytes, involving activation of pattern recognition receptors (PRRs) and cytokine signaling pathways. To better understand the coordinated systemic immune response in AH patients, we performed combined single-cell transcriptome, cell-surface protein, and lymphocyte antigen receptor analysis of peripheral blood mononuclear cell (PBMC) samples. Our results showed inflammatory cytokines and chemokines were highly expressed in AH, including IL-2, IL-32, CXC3R1 and CXCL16 in monocytes and NK cells, whereas HLA-DR genes were reduced in monocytes. In addition, we also found altered differentiation of T-helper cells (TH1 and TH17), which could further lead to neutrophil recruitment and macrophage activation. Lastly, our results also suggest impaired NK-cell activation and differentiation in AH with reduced gene expression of KLRC2 and increased gene expression of KLRG1. Our findings indicate different mechanisms may be involved in impaired immune and inflammatory responses for the cellular subtypes of the PBMCs in AH.

Dysregulation of a lncRNA within the TNFRSF10A locus activates cell death pathways

TNFRSF10A (tumor necrosis factor receptor superfamily member 10A) encodes a cell surface receptor protein involved in apoptotic, necroptotic, and inflammatory pathways. Dysregulation of TNFRSF10A has been implicated in sensitization to apoptosis and to the development of multiple diseases, yet little is known of the AC100861.1 long noncoding RNA (lncRNA) that lies head-to-head with TNFRSF10A. Given its genomic positioning, we sought to investigate the function of AC100861.1, focusing on its potential relationship with TNFRSF10A and the role it may play in death receptor signaling. Using knockdown and overexpression strategies, we probed cell viability and examined transcript and protein-level changes in key genes involved in apoptosis, necroptosis, and inflammation. Decreased cell viability was observed upon TNFRSF10A overexpression, regardless of whether the cells were subjected to the chemical stressor tunicamycin. Similarly, overexpression of AC100861.1 led to increased cell death, with a further increase observed under conditions of cellular stress. Knockdown of TNFRSF10A increased cell death only when the cells were stressed, and AC100861.1 knockdown exhibited no effect on cell death. Neither knockdown nor overexpression of either of these genes greatly affected the expression of the other. Manipulating AC100861.1, however, led to marked changes in the expression of genes involved in necroptosis and inflammatory cell-signaling pathways. Additionally, RNA fluorescence in situ hybridization (RNA-FISH) revealed that the AC100861.1 transcript is localized primarily to the cytoplasm. Together, these data suggest that AC100861.1 may have a role in regulating necroptotic and inflammatory signaling pathways and that this function is separate from changes in TNFRSF10A expression. Given the importance of this genomic locus for cell survival, these data provide insight into the function of a poorly understood lncRNA with potential implications regarding disease pathology and treatment.

A phase 2 open-label study of conditionally active biologic ozuriftamab vedotin (BA3021) in failed PD-1/L1 treatment of patients with recurrent or metastatic squamous cell carcinoma of the head and neck.

TPS6107 Background: Ozuriftamab vedotin (BA3021) is a conditionally active biologic (CAB) anti-receptor tyrosine kinase orphan receptor 2 (ROR2) humanized monoclonal antibody (IgG1) conjugated to monomethyl auristatin E (MMAE) using a cleavable linker (CAB ROR2 ADC) (Short, et al., 2014, Chang, et al. 2021). Conditional and reversible binding by CABs is designed to reduce off-tumor toxicity and immunogenicity, avoid tissue-mediated drug deposition, and improve pharmacokinetics (PK). ROR2 is a cell-surface transmembrane receptor protein tyrosine kinase highly expressed in several tumor types including head and neck squamous cell cancer (HNSCC). Increased ROR2 expression has been associated with tumor resistance to chemotherapy, programmed death-1 (PD-1) inhibitors, molecular targeted therapy, and radiation therapy. A pronounced unmet need exists as the majority of patients with recurrent or metastatic HNSCC experience disease progression with existing therapies (Chow 2020). Methods: BA3021-002 is a multi-center, open-label, single-arm Phase 2 study (n=40) designed to evaluate the efficacy and safety of BA3021 in patients previously treated with PD-(L)1 with ROR-2 expressing recurrent or metastatic HNSCC. Eligible patients include those with measurable disease by Response Evaluation Criteria in Solid Tumors (RECIST) Version 1.1 criteria. Failure to prior treatment is defined as documented disease progression after no more than one PD-1/L1 inhibitor either administered as monotherapy or in combination therapy. Pharmacokinetic (PK), pharmacodynamic (PD), immunogenicity, and biomarker assessments will be performed. Enrollment is ongoing (NCT05271604)

Distribution of Glycolipids in the Plasma Membrane Monitored by Specific Probes in Combination with Sodium Dodecyl Sulfate-Digested Freeze-Fracture Replica Labeling (SDS-FRL).

Glycolipids are mainly distributed in the outer leaflet of the plasma membrane and are involved in cellular signaling by modulating the activity of cell surface receptor proteins. Glycolipids themselves also work as cell surface receptors of bacterial toxins. Anti-glycolipid antibodies are associated with various pathological conditions. The cellular distribution of glycolipids has been studied using specific toxins or antibodies. However, these proteins are multivalent and thus potentially induce the artificial aggregation of glycolipids. Since chemical fixative such as paraformaldehyde does not fix glycolipids, an alternative methodology is required to localize glycolipids with multivalent probes. Sodium dodecyl sulfate-digested freeze-fracture replica labeling (SDS-FRL) physically fixes glycolipids on the cast after quick freezing. Thus, SDS-FRL provides the opportunity to observe the natural distribution of glycolipids using multivalent probes. Here, we describe the application of SDS-FRL on the cell surface distribution of phosphatidylglucoside.

Discovery of natural products to block SARS-CoV-2 S-protein interaction with Neuropilin-1 receptor: A molecular dynamics simulation approach.

Neuropilin-1 (NRP1) is a widely expressed cell surface receptor protein characterized by its pleiotropic function. Recent reports highlighted NRP1 as an additional entry point of the SARS-CoV-2 virus, enhancing viral infectivity by interacting with the S-protein of SARS-CoV-2. The ubiquitous distribution and mechanism of action of NRP1 enable the SARS-CoV-2 virus to attack multiple organs in the body simultaneously. Therefore, blocking NRP1 is a potential therapeutic approach against SARS-CoV-2 infection. The current study screened the South African natural compounds database (SANCDB) for molecules that can disrupt the SARS-CoV-2 S protein-NRP1 interaction as a potential antiviral target for SARS-CoV-2 cellular entry. Following excessive screening and validation analysis 3-O-Methylquercetin and Esculetin were identified as potential compounds to disrupt the S-protein-NRP1 interaction. Furthermore, to understand the conformational stability and dynamic features between NRP1 interaction with the selected natural products, we performed 200 ns molecular dynamics (MD) simulations. In addition, molecular mechanics-generalized Born surface area (MM/GBSA) was utilized to calculate the free binding energies of the natural products interacting with NRP1. 3-O-methylquercetin showed an inhibitory effect with binding energies ΔG of −25.52 ± 0.04 kcal/mol to NRP1, indicating the possible disruption of the NRP1-S-protein interaction. Our analysis demonstrated that 3-O-methylquercetin presents a potential antiviral compound against SARS-CoV-2 infectivity. These results set the path for future functional in-vitro and in-vivo studies in SARS-CoV-2 research.

Highly active selenium nanotherapeutics combined with metformin to achieve synergistic sensitizing effect on NK cells for osteosarcoma therapy

Abstract NK cells-based cancer therapy combined with chemotherapeutic drugs for the treatment of tumors can enhance the immunosensitivity of NK cells, increase the expression of NK cell receptors, and eventually boost the killing effect of NK cells on cancer cells. Selenium (Se) with different chemical structures can be metabolized into selenoproteins to regulate tumor and immune cells’ fate and functions. Herein, we found that, functionalized Se nanoparticles (SeNPs) combining with metformin (met) could amply the immunotherapeutic effects of NK92 cells against osteosarcoma cancer. The results revealed that TW80-SeNPs combined with met had the optimum performance on NK92 cells for HepG2 cells, owing to the increased ROS in HepG2 cells and the augmented expression of cell surface receptor proteins ULBP-3/4, PD-L1, MICA, and NK92 cell surface receptor proteins PD-1 and FasL. Additionally, TW80-SeNPs were gradually metabolized into selenoproteins (Gpx4 and TR1) into human osteosarcoma MG63 cells to reinforce the anticancer effect of NK92 cells by regulating the redox balance in the tumor microenvironment. This study provides a therapeutic approach in treating cancer itself or diabetes coupled with cancer. Moreover, it provides a multidrug strategy to improve immune cell function in practical applications, especially for synergistic immunotherapy of osteosarcoma.

What Makes GPCRs from Different Families Bind to the Same Ligand?

G protein-coupled receptors (GPCRs) are the largest class of cell-surface receptor proteins with important functions in signal transduction and often serve as therapeutic drug targets. With the rapidly growing public data on three dimensional (3D) structures of GPCRs and GPCR-ligand interactions, computational prediction of GPCR ligand binding becomes a convincing option to high throughput screening and other experimental approaches during the beginning phases of ligand discovery. In this work, we set out to computationally uncover and understand the binding of a single ligand to GPCRs from several different families. Three-dimensional structural comparisons of the GPCRs that bind to the same ligand revealed local 3D structural similarities and often these regions overlap with locations of binding pockets. These pockets were found to be similar (based on backbone geometry and side-chain orientation using APoc), and they correlate positively with electrostatic properties of the pockets. Moreover, the more similar the pockets, the more likely a ligand binding to the pockets will interact with similar residues, have similar conformations, and produce similar binding affinities across the pockets. These findings can be exploited to improve protein function inference, drug repurposing and drug toxicity prediction, and accelerate the development of new drugs.

Abstract 4081: Leveraging single-cell RNA sequencing data to design multi-targeting SeekRRNA therapeutics

Abstract SeekR™ chimeric molecules consist of dual flanking RNA aptamers designed to bind specific proteins (BINDERS), joined by a double stranded RNA bridge that encodes multiple siRNAs designed to silence select disease target genes (SILENCERS). Aptamers are folded nucleic acid chains that act much like chemical antibodies in that they can bind proteins in a sequence-specific manner. By identifying RNA aptamers capable of seeking and binding to specific cell surface protein receptors, SeekR™ RNA therapeutics can be engineered to self-deliver to a particular receptor defined tissue type. For example, a SeekR™ can be directed to prostate tumors that selectively express PSMA. The combination of two RNA aptamer binders with two siRNA silencers thus enables the selective delivery of the siRNAs to tumor cells expressing the binder target, wherein it directs sequence-specific silencing of cancer target genes. To identify and prioritize the right combination of SeekR targets, we have taken advantage of single-cell sequencing (scRNA-seq) data sets. By analyzing scRNA-seq data, we can identify specific cell populations within tumors to co-target with an aptamer and siRNA. We leveraged several publicly available colon and non-small cell lung cancer scRNA data sets for this analysis. A custom analysis pipeline was applied to these data to identify specific cell types within tumor samples. We then profiled specific cancer targets and determined percentages of target co-expression within a single tumor compared to normal cells. This provides information for cell-type-specific targeting to reduce potential toxicity within non-tumor tissue. In addition to targeting aptamers, we performed ligand-receptor analyses to prioritize specific siRNA targets in particular cell types within the tumor environment. This analysis revealed novel combinations of binders and silencers that will more precisely deliver the right multi-targeted gene silencing to the correct cell types. In summary, scRNA-seq data provide a rich resource of data to direct SeekR™ development and optimization. Citation Format: Susan Massey, Richard Hsiao, Shweta Yadav, David Azorsa, Spyro Mousses, Jeffrey A. Kiefer. Leveraging single-cell RNA sequencing data to design multi-targeting SeekRRNA therapeutics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4081.

Plasma Membrane-Derived Liposomes Exhibit Robust Antiviral Activity against HSV-1.

Plasma membranes host a plethora of proteins and glycans on their outer surface that are exploited by viruses to enter the cells. In this study, we have utilized this property to limit a viral infection using plasma membrane-derived vesicles. We show that plasma membrane-derived liposomes are prophylactically and therapeutically competent at preventing herpes simplex virus type-1 (HSV-1) infection. Plasma membrane liposomes derived from human corneal epithelial (HCE) cells, which are natural targets of HSV-1 infection, as well as Vero and Chinese hamster ovary (CHO) cells were used in this study. Our study clearly demonstrates that HCE and Vero-derived cellular liposomes, which express the viral entry-specific cell surface protein receptors, exhibit robust antiviral activity especially when compared to CHO-derived liposomes, which lack the relevant HSV-1 entry receptors. Further experimentation of the plasma membrane-derived liposomes with HSV type-2 (HSV-2) and pseudorabies virus yielded similar results, indicating strong potential for the employment of these liposomes to study viral entry mechanisms in a cell free-environment.

Assessing the Chemosensitizing Effect of Neferine on Cisplatin-Resistant Colorectal Cancer Cells through Molecular Docking Studies

Colorectal cancer (CRC) is the second deadliest diseases next to lung cancer. Cisplatin is the first generation platinum based alkylating agent using for treatment of advance CRC patients. Continuous usages of cisplatin lead to resistance which limits its therapeutic efficacy. Recent research is focused on studying the chemotherapeutic efficacy of the phytochemicals as they are less toxic compared to the conventional chemotherapeutic drugs. Neferine is a bisbenzylisoquinoline alkaloid extracted from the embryo of Nelumbo nucifera. The anticancer and chemosensitizing effect of neferine has been well reported in several cancer cells. However, there are no reports on the chemosensitizing effect of neferine on cisplatin-resistant colorectal cancer cells (CRCs). Hence, the present study aims at identification of target proteins responsible for cisplatin-resistance in colorectal cancer cells. The present investigation elucidates the specific interaction of neferine with various cell surface receptor proteins related to cisplatin-resistance, multi-drug resistance (MDR) proteins, signal transduction protein and transcription factors via molecular docking approach. The interaction between neferine and the target proteins of cisplatin-resistant colorectal cancer was analyzed through Schrodinger Maestro 11.9 module. From our docking studies we could suggest that neferine is most active for insulin-like growth factor-1 receptor (IGF1R), fibroblast growth factor receptor-2 (FGFR2), zinc finger protein SNAI1 (SNAIL1), signal transducer and activator of transcription-3 (STAT3) and transforming growth factor beta receptor-1 (TGFβR1) when sorted according to their docking score.

CRISPA: A Non-viral, Transient Cas9 Delivery System Based on Reengineered Anthrax Toxin.

Translating the CRISPR/Cas9 genome editing technology into clinics is still hampered by rather unspecific, unsafe and/or inconvenient approaches for the delivery of its main components - the Cas9 endonuclease and a guide RNA - into cells. Here, we describe the development of a novel transient and non-viral Cas9 delivery strategy based on the translocation machinery of the Bacillus anthracis anthrax toxin, PA (protective antigen). We show that Cas9 variants fused to the N-terminus of the lethal factor or to a hexahistidine tag are shuttled through channels formed by PA into the cytosol of human cells. As proof-of-principle, we applied our new approach, denoted as CRISPA, to knock out lipolysis-stimulated lipoprotein receptor (LSR) in the human colon cancer cell line HCT116 and green-fluorescent protein (GFP) in human embryonic kidney 293T cells stably expressing GFP. Notably, we confirmed that the transporter PA can be adapted to recognize specific host cell-surface receptor proteins and may be optimized for cell type-selective delivery of Cas9. Altogether, CRISPA provides a novel, transient and non-viral way to deliver Cas9 into specific cells. Thus, this system is an additional step towards safe translation of the CRISPR/Cas9 technology into clinics.

Molecular mechanism of anti-SARS-CoV2 activity of Ashwagandha-derived withanolides

COVID-19 caused by SARS-CoV-2 corona virus has become a global pandemic. In the absence of drugs and vaccine, and premises of time, efforts and cost required for their development, natural resources such as herbs are anticipated to provide some help and may also offer a promising resource for drug development. Here, we have investigated the therapeutic prospective of Ashwagandha for the COVID-19 pandemic. Nine withanolides were tested in silico for their potential to target and inhibit (i) cell surface receptor protein (TMPRSS2) that is required for entry of virus to host cells and (ii) viral protein (the main protease Mpro) that is essential for virus replication. We report that the withanolides possess capacity to inhibit the activity of TMPRSS2 and Mpro. Furthermore, withanolide-treated cells showed downregulation of TMPRSS2 expression and inhibition of SARS-CoV-2 replication in vitro, suggesting that Ashwagandha may provide a useful resource for COVID-19 treatment.

How to Optimize Treatment With Ustekinumab in Inflammatory Bowel Disease: Lessons Learned From Clinical Trials and Real-World Data.

Ustekinumab is a fully human IgG1 monoclonal antibody that has been approved for the treatment of moderate to severe Crohn's disease, and more recently moderate to severe ulcerative colitis. It binds with high affinity to the p40 subunit of human interleukin-12 and 23. This mechanism of action prevents the bioactivity of both interleukins, thus precluding their interaction with the cell surface receptor protein. The pivotal clinical trials (UNITI-1, UNITI-2 and IM-UNITI) demonstrated its clinical efficacy and safety, in naïve patients and also in those previously exposed to immunosuppressants and/or biologics. There is now an extensive experience with its use worldwide, corroborating its favorable profile even in patients with refractory disease. However, the number of medical treatment options available in inflammatory bowel disease are still limited. Hence, we should prioritize the treatments that have a greater probability of response in an individual patient. Our aim was to review and summarize all the available literature regarding the potential predictors of response to ustekinumab that can increase the success rate with this therapy in clinical practice.

Critical Sequence Hotspots for Binding of Novel Coronavirus to Angiotensin Converter Enzyme as Evaluated by Molecular Simulations.

The novel coronavirus (nCOV-2019) outbreak has put the world on edge, causing millions of cases and hundreds of thousands of deaths all around the world, as of June 2020, let alone the societal and economic impacts of the crisis. The spike protein of nCOV-2019 resides on the virion’s surface mediating coronavirus entry into host cells by binding its receptor binding domain (RBD) to the host cell surface receptor protein, angiotensin converter enzyme (ACE2). Our goal is to provide a detailed structural mechanism of how nCOV-2019 recognizes and establishes contacts with ACE2 and its difference with an earlier severe acute respiratory syndrome coronavirus (SARS-COV) in 2002 via extensive molecular dynamics (MD) simulations. Numerous mutations have been identified in the RBD of nCOV-2019 strains isolated from humans in different parts of the world. In this study, we investigated the effect of these mutations as well as other Ala-scanning mutations on the stability of the RBD/ACE2 complex. It is found that most of the naturally occurring mutations to the RBD either slightly strengthen or have the same binding affinity to ACE2 as the wild-type nCOV-2019. This means that the virus had sufficient binding affinity to its receptor at the beginning of the crisis. This also has implications for any vaccine design endeavors since these mutations could act as antibody escape mutants. Furthermore, in silico Ala-scanning and long-timescale MD simulations highlight the crucial role of the residues at the interface of RBD and ACE2 that may be used as potential pharmacophores for any drug development endeavors. From an evolutional perspective, this study also identifies how the virus has evolved from its predecessor SARS-COV and how it could further evolve to become even more infectious.

Attenuating effect of Indole-3-Carbinol on gold nanoparticle induced hepatotoxicity in rats

Indole-3-carbinol (I3C) is a plant based compound present in vegetables mostly belonging to cruciferous family. I3C has been shown to possess anticancer, antioxidant and anti-inflammatory properties. Humans are increasingly being exposed to GNPs due an due to their widespread and increased applications in different fields. Consistently, recent animal and cell based studies have found them to be carcinogenic, prooxidant and inflammatory. This study sought to examine the beneficial effects of I3C against oxidative stress, inflammation and histopathological changes in liver tissues of rats administered with GNPs. Forty rats randomly divided into four groups: G1 control G2, rats injected i.p. with a suspension of GNPs (10 nm in size) (20 μg/kg body wgt) for 7 days; G3, rats supplemented orally with I3C (150 mg/kg body wgt) for 7 days; and G4, rats injected with GNPs along with oral supplementation ofI3C. Compared to control, rats administered with GNPs had significantly increased liver functional markers including ALT, AST, ALP, total and direct bilirubin and significantly decreased albumin levels. GNP administered rats also demonstrated increased oxidative stress and inflammatory markers, MDA, 8-OHdG and IL-6 levels and significantly depleted activities of antioxidants such as glutathione reductase (GR) and glutathione S-transferase (GST), and transcription factor, Nrf2 compared to control. GNPs also exerted marked histological changes in liver tissues. Treatment with I3C significantly restored the GNP induced changes in the levels of all the studied parameters and also prevented pathological changes in liver tissues. Molecular docking studies confirm the interaction of I3C with hepatic cell surface receptor protein LT3 and thereby blocking GNPs from binding to I3C, confirming above experimental findings. Collectively, the data demonstrate the hepatoprotective effects of I3C against GNP-induced adverse effects on liver tissue. These protective effects of I3C appear to be mediated by its ability to downregulate oxidative stress and inflammation. Thus dietary intake of plant products rich in I3C may have beneficial health effects.

Unraveling the sugar code: the role of microbial extracellular glycans in plant-microbe interactions.

To defend against microbial invaders but also to establish symbiotic programs, plants need to detect the presence of microbes through the perception of molecular signatures characteristic of a whole class of microbes. Among these molecular signatures, extracellular glycans represent a structurally complex and diverse group of biomolecules that has a pivotal role in the molecular dialog between plants and microbes. Secreted glycans and glycoconjugates such as symbiotic lipochitooligosaccharides or immunosuppressive cyclic β-glucans act as microbial messengers that prepare the ground for host colonization. On the other hand, microbial cell surface glycans are important indicators of microbial presence. They are conserved structures normally exposed and thus accessible for plant hydrolytic enzymes and cell surface receptor proteins. While the immunogenic potential of bacterial cell surface glycoconjugates such as lipopolysaccharides and peptidoglycan has been intensively studied in the past years, perception of cell surface glycans from filamentous microbes such as fungi or oomycetes is still largely unexplored. To date, only few studies have focused on the role of fungal-derived cell surface glycans other than chitin, highlighting a knowledge gap that needs to be addressed. The objective of this review is to give an overview on the biological functions and perception of microbial extracellular glycans, primarily focusing on their recognition and their contribution to plant–microbe interactions.

Engineering G-quadruplex aptamer to modulate its binding specificity.

The use of aptamers in bioanalytical and biomedical applications exploits their ability to recognize cell surface protein receptors. Targeted therapeutics and theranostics come to mind in this regard. However, protein receptors occur on both cancer and normal cells; as such, aptamers are now taxed with identifying high vs. low levels of protein expression. Inspired by the flexible template mechanism and elegant control of natural nucleic acid-based structures, we report an allosteric regulation strategy for constructing a structure-switching aptamer for enhanced target cell recognition by engineering aptamers with DNA intercalated motifs (i-motifs) responsive to the microenvironment, such as pH. Structure-switching sensitivity can be readily tuned by manipulating i-motif sequences. However, structure-switching sensitivity is difficult to estimate, making it equally difficult to effectively screen modified aptamers with the desired sensitivity. To address this problem, we selected a fluorescent probe capable of detecting G-quadruplex in complicated biological media.