Single-cell discovery of m6A RNA modifications in the hippocampus.

N 6-Methyladenosine (m6A) is a prevalent and highly regulated RNA modification essential for RNA metabolism and normal brain function. It is particularly important in the hippocampus, where m6A is implicated in neurogenesis and learning. Although extensively studied, its presence in specific cell types remains poorly understood. We investigated m6A in the hippocampus at a single-cell resolution, revealing a comprehensive landscape of m6A modifications within individual cells. Through our analysis, we uncovered transcripts exhibiting a dense m6A profile, notably linked to neurological disorders such as Alzheimer's disease. Our findings suggest a pivotal role of m6A-containing transcripts, particularly in the context of CAMK2A neurons. Overall, this work provides new insights into the molecular mechanisms underlying hippocampal physiology and lays the foundation for future studies investigating the dynamic nature of m6A RNA methylation in the healthy and diseased brain.

How kelch domain-containing protein 3 distinguishes between the C-end degron of herpesviral protein UL49.5 and its mutants - Insights from molecular dynamics.

The C-terminal residues of proteins can function as degrons recognized by ubiquitin ligases for proteasomal degradation. Kelch domain-containing protein 3 (KLHDC3) is a substrate receptor for E3 ubiquitin ligase (Cullin2-RING ligase) that targets the C-terminal degrons. UL49.5 is 96 amino-acid type 1 transmembrane protein from bovine herpesvirus 1. Herpesviruses have evolved highly effective strategies to evade the antiviral immune response. One of these strategies is inhibition of the antigen processing and presentation pathway by MHC I, thereby reducing the presentation of the antigenic peptides on the surface of the infected cell. Recently, it has been demonstrated that UL49.5 triggers TAP degradation via recruiting the E3 ubiquitin ligase to TAP. Moreover, the mutagenesis revealed that the mutations within the UL49.5 C-degron sequence (93RGRG96) affect binding of UL49.5 to KLHDC3. In this work the molecular dynamics of KLHDC3 in complexes with the C-terminal decapeptide of the herpesviral protein UL4.95 and its three mutants has been employed to provide a framework for understanding molecular recognition of UL49.5 by KLHDC3. The findings of this study give insights into the interactions of the various degrons with KLHDC3. During the molecular dynamics, an active RGKG mutant adopts a conformation similar to that of the wild type decapeptide, whereas the conformations of two inactive mutants, KGRG and RGRD are significantly different. Both R93K and G96D mutations impair the interactions of the C-terminal glycine with KLHDC3. The findings of this study expand the existing knowledge about the mechanism of protein recognition by Cullin2-RING ligases thus contributing to the design of antiviral and anticancer drugs that can selectively promote or inhibit degradation of the proteins of interest.

Three musketeers of PDA-based MRI contrasting and therapy.

Polydopamine (PDA) stands as a versatile material explored in cancer nanomedicine for its unique properties, offering opportunities for multifunctional drug delivery platforms. This study explores the potential of utilizing a one-pot synthesis to concurrently integrate Fe, Gd and Mn ions into porous PDA-based theranostic drug delivery platforms called Ferritis, Gadolinis and Manganis, respectively. Our investigation spans the morphology, magnetic properties, photothermal characteristics and cytotoxicity profiles of those potent nanoformulations. The obtained structures showcase a spherical morphology, robust magnetic response and promising photothermal behaviour. All of the presented nanoparticles (NPs) display pronounced paramagnetism, revealing contrasting potential for MRI imaging. Relaxivity values, a key determinant of contrast efficacy, demonstrated competitive or superior performance compared to established, used contrasting agents. These nanoformulations also exhibited robust photothermal properties under near infra-red irradiation, showcasing their possible application for photothermal therapy of cancer. Our findings provide insights into the potential of metal-doped PDA NPs for cancer theranostics.

Functional maturation and longitudinal imaging of intraportal neonatal porcine islet grafts in genetically diabetic pigs.

Allogeneic intraportal islet transplantation (ITx) has become an established treatment for patients with poorly controlled type 1 diabetes. However, the loss of viable beta-cell mass after transplantation remains a major challenge. Therefore, noninvasive imaging methods for long-term monitoring of the transplant fate are required. In this study, [68Ga]Ga-DOTA-exendin-4 positron emission tomography/computed tomography (PET/CT) was used for repeated monitoring of allogeneic neonatal porcine islets (NPI) after intraportal transplantation into immunosuppressed genetically diabetic pigs. NPI transplantation (3320-15,000 islet equivalents per kg body weight) led to a reduced need for exogenous insulin therapy and finally normalization of blood glucose levels in 3 out of 4 animals after 5 to 10 weeks. Longitudinal PET/CT measurements revealed a significant increase in standard uptake values in graft-bearing livers. Histologic analysis confirmed the presence of well-engrafted, mature islet clusters in the transplanted livers. Our study presents a novel large animal model for allogeneic intraportal ITx. A relatively small dose of NPIs was sufficient to normalize blood glucose levels in a clinically relevant diabetic pig model. [68Ga]Ga-DOTA-exendin-4 PET/CT proved to be efficacious for longitudinal monitoring of islet transplants. Thus, it could play a crucial role in optimizing ITx as a curative therapy for type 1 diabetes.

The herpesvirus UL49.5 protein hijacks a cellular C-degron pathway to drive TAP transporter degradation.

The transporter associated with antigen processing (TAP) is a key player in the major histocompatibility class I-restricted antigen presentation and an attractive target for immune evasion by viruses. Bovine herpesvirus 1 impairs TAP-dependent antigenic peptide transport through a two-pronged mechanism in which binding of the UL49.5 gene product to TAP both inhibits peptide transport and triggers its proteasomal degradation. How UL49.5 promotes TAP degradation has, so far, remained unknown. Here, we use high-content siRNA and genome-wide CRISPR-Cas9 screening to identify CLR2KLHDC3 as the E3 ligase responsible for UL49.5-triggered TAP disposal. We propose that the C terminus of UL49.5 mimics a C-end rule degron that recruits the E3 to TAP and engages the cullin-RING E3 ligase in endoplasmic reticulum-associated degradation.

An intrinsic network of polar interactions is responsible for binding of UL49.5 C-degron by the CRL2KLHDC3 ubiquitin ligase.

Bovine herpesvirus type 1 (BoHV-1) is a pathogen of cattle responsible for infectious bovine rhinotracheitis. The BoHV-1 UL49.5 is a transmembrane protein that binds to the transporter associated with antigen processing (TAP) and downregulates cell surface expression of the antigenic peptide complexes with the major histocompatibility complex class I (MHC-I). KLHDC3 is a kelch domain-containing protein 3 and a substrate receptor of a cullin2-RING (CRL2) E3 ubiquitin ligase. Recently, it has been identified that CRL2KLHDC3 is responsible for UL49.5-triggered TAP degradation via a C-degron pathway and the presence of the degron sequence does not lead to the degradation of UL49.5 itself. The molecular modeling of KLHDC3 in complexes with four UL49.5 C-terminal decapeptides (one native protein and three mutants) revealed their activity to be closely correlated with the conformation which they adopt in KLHDC3 binding cleft. To analyze the interaction between UL49.5 and KLHDC3 in detail, in this work a total of 3.6 µs long molecular dynamics simulations have been performed. The complete UL49.5-KLHDC3 complexes were embedded into the fully hydrated all-atom lipid membrane model with explicit water molecules. The network of polar interactions has been proposed to be responsible for the recognition and binding of the degron in KLHDC3. The interaction network within the binding pocket appeared to be very similar between two CRL2 substrate receptors: KLHDC3 and KLHDC2.

Fat from Hermetia illucens Alters the Cecal Gut Microbiome and Lowers Hepatic Triglyceride Concentration in Comparison to Palm Oil in Obese Zucker Rats.

BACKGROUND: Palm oil (PO) is the most widely utilized plant oil for food production. Owing to the great ecologic problems associated with PO production, sustainably produced fats, such as insect fat, might be a suitable alternative. OBJECTIVES: The hypothesis was tested that fat from Hermetia illucens larvae (HF) compared with PO and soybean oil (SO) has no adverse effects on hepatic lipid metabolism, plasma metabolome, and cecal microbiome in obese Zucker rats. METHODS: Thirty male obese Zucker rats were randomly assigned to 3 groups (SO, PO, HF; n = 10 rats/group) and fed 3 different semisynthetic diets containing either SO, PO, or HF as the main fat source for 4 wk. The effects were evaluated by measurement of liver and plasma lipid concentrations, liver transcriptomics, targeted plasma metabolomics, and cecal microbiomics. RESULTS: Supplementation of HF reduced hepatic triglyceride concentration and messenger ribonucleic acid concentrations of selected genes involved in fatty acid and triglyceride synthesis in comparison to PO (P < 0.05). Pairwise comparison of the Simpson index and Jaccard index showed a higher cecal microbial α- and ß-diversity in rats fed the HF diet than in rats fed the PO diet (P = 0.015 and P = 0.027), but no difference between rats fed the diets with SO or PO. Taxonomic analysis of the cecal microbial community revealed a lower abundance of Clostridium_sensu_stricto_1 and a higher abundance of Blautia, Mucispirillum, Anaerotruncus, Harryflintia, and Peptococcus in rats supplemented with HF than in rats supplemented with PO (P < 0.05). CONCLUSIONS: HF, compared with PO, has liver lipid-lowering effects in obese Zucker rats, which may be caused by a shift in the gut microbial community. Thus, HF might serve as a sustainably produced fat alternative to PO for food production.

Deterministic nuclear reprogramming of mammalian nuclei to a totipotency-like state by Amphibian meiotic oocytes for stem cell therapy in humans.

The ultimate aim of nuclear reprogramming is to provide stem cells or differentiated cells from unrelated cell types as a cell source for regenerative medicine. A popular route towards this is transcription factor induction, and an alternative way is an original procedure of transplanting a single somatic cell nucleus to an unfertilized egg. A third route is to transplant hundreds of cell nuclei into the germinal vesicle (GV) of a non-dividing Amphibian meiotic oocyte, which leads to the activation of silent genes in 24 h and robustly induces a totipotency-like state in almost all transplanted cells. We apply this third route for potential therapeutic use and describe a procedure by which the differentiated states of cells can be reversed so that totipotency and pluripotency gene expression are regained. Differentiated cells are exposed to GV extracts and are reprogrammed to form embryoid bodies, which shows the maintenance of stemness and could be induced to follow new directions of differentiation. We conclude that much of the reprogramming effect of eggs is already present in meiotic oocytes and does not require cell division or selection of dividing cells. Reprogrammed cells by oocytes could serve as replacements for defective adult cells in humans.

Effect of Hermetia illucens Fat, Compared with That of Soybean Oil and Palm Oil, on Hepatic Lipid Metabolism and Plasma Metabolome in Healthy Rats.

Palm oil (PO) is currently the most widely used fat source for food production, but insect fat from Hermetia illucens larvae (HF) might be a suitable alternative fat source, because its production is less harmful to the environment. The present study investigated the effect of HF, as compared to PO and soybean oil (SO), on the hepatic lipid metabolism and the plasma metabolome of healthy rats, which were randomly assigned to three groups (n = 10 rats/group), and fed three different semi-synthetic diets containing either SO, PO, or HF as the main fat source for 4 weeks. Feed intake, body weight gain, liver and plasma lipid concentrations, and the hepatic mRNA levels of genes involved in lipid metabolism and inflammation did not differ between groups. Targeted plasma metabolomics revealed 294 out of 630 metabolites analyzed to be different between groups. Principal component analysis showed a clear separation of the plasma metabolomes of the SO group and the other two groups, but no separation of those of the PO and the HF groups. The present study shows that HF exerts no adverse metabolic effects in healthy rats, compared to PO or SO, indicating that HF is a safe alternative fat source to PO for food production.

Biomimetic theranostic nanoparticles for effective anticancer therapy and MRI imaging.

Cancer remains a leading cause of mortality worldwide, necessitating the development of innovative therapeutic approaches. Nanoparticle-based drug delivery systems have garnered significant interest due to their multifunctionality, offering the potential to enhance cancer treatment efficacy and improve patient tolerability. Membrane-coated drug delivery systems hold great potential for enhancing the therapeutic outcome of nanoparticle-based anticancer therapies. In this study, we report the synthesis of multifunctional iron-functionalized mesoporous polydopamine nanoparticles (MPDAFe NPs). These nanoformulations demonstrate substantial potential for combining efficient drug delivery and magnetic resonance imaging (MRI) and showcase the advantages of biomimetic coating with tumor cell-derived membranes. This coating confers prolonged circulation and improved the targeting capabilities of the nanoparticles. Furthermore, comprehensive biosafety evaluations reveal negligible toxicity to normal cells, while the combined chemo- and phototherapy exhibited significant cytotoxicity towards cancer cells. Additionally, the photothermal effect evaluation highlights the enhanced cytotoxicity achieved through laser irradiation, showcasing the synergistic effects of the nanomaterials and photothermal therapy. Importantly, our chemotherapeutic effect evaluation demonstrates the superior efficacy of doxorubicin-loaded MPDAFe@Mem NPs (cancer cell membrane-coated MPDAFe NPs) in inhibiting cancer cell viability and proliferation, surpassing the potency of free doxorubicin. This study comprehensively investigates theranostic, membrane-coated drug delivery systems, underlining their potential to increase the efficacy of cancer treatment strategies. The multifunctional nature of the iron-functionalized polydopamine nanoparticles allows for efficient drug delivery and imaging capabilities, while the biomimetic coating enhances their biocompatibility and targeting ability. These findings contribute valuable insights towards the development of advanced nanomedicine for improved cancer therapeutics.

The herpesvirus UL49.5 protein hijacks a cellular C-degron pathway to drive TAP transporter degradation.

The transporter associated with antigen processing (TAP) is a key player in the MHC class I-restricted antigen presentation and an attractive target for immune evasion by viruses. Bovine herpesvirus 1 (BoHV-1) impairs TAP-dependent antigenic peptide transport through a two-pronged mechanism in which binding of the UL49.5 gene product to TAP both inhibits peptide transport and promotes its proteasomal degradation. How UL49.5 promotes TAP degradation is unknown. Here, we use high-content siRNA and genome-wide CRISPR-Cas9 screening to identify CLR2KLHDC3 as the E3 ligase responsible for UL49.5-triggered TAP disposal in human cells. We propose that the C-terminus of UL49.5 mimics a C-end rule degron that recruits the E3 to TAP and engages the CRL2 E3 in ER-associated degradation.

Mesenchymal stem/stromal cells-derived extracellular vesicles as a potentially more beneficial therapeutic strategy than MSC-based treatment in a mild metabolic osteoarthritis model.

BACKGROUND: Mesenchymal stromal/stem cells (MSCs) and MSC-derived extracellular vesicles (MSC-EVs) hold promise as a disease modifying treatment in osteoarthritis (OA). Obesity, and its associated inflammation, contribute to OA development and metabolic OA represents a specific and significant group of the OA patient population. Given their immunomodulatory properties, MSC and MSC-EVs are especially interesting for this group of patients as a therapeutic option. Here, we were the first to compare the therapeutic efficacy of MSCs and MSC-EVs in a mild OA model taking these metabolic aspects into consideration. METHODS: Male Wistar-Han rats (Crl:WI(Han) (n = 36) were fed a high fat diet for 24 weeks, with unilateral induction of OA by groove surgery after 12 weeks. Eight days after surgery rats were randomized in three treatment groups receiving MSCs, MSC-EVs or vehicle injection. Pain-associated behavior, joint degeneration, and local and systemic inflammation were measured. RESULTS: We demonstrated that despite not having a significant therapeutic effect, MSC-EV treatment results in lower cartilage degeneration, less pain behaviour, osteophytosis and joint inflammation, than MSC treatment. Suggesting that MSC-EVs could be a more promising therapeutic strategy than MSCs in this mild metabolic OA model. CONCLUSION: In summary, we find that MSC treatment has negative effects on the joint in metabolic mild OA. This is an essential finding for the significant group of patients with metabolic OA phenotype, and might help to understand why clinical translation of MSC treatment shows varying therapeutic efficacy thus far. Our results also suggest that MSC-EV-based treatment might be a promising option for these patients, however MSC-EV therapeutic efficacy will need improvement.

m6 A promotes planarian regeneration.

Regeneration is the regrowth of damaged tissues or organs, a vital process in response to damages from primitive organisms to higher mammals. Planarian possesses active whole-body regenerative capability owing to its vast reservoir of adult stem cells, neoblasts, providing an ideal model to delineate the underlying mechanisms for regeneration. RNA N6 -methyladenosine (m6 A) modification participates in many biological processes, including stem cell self-renewal and differentiation, in particular the regeneration of haematopoietic stem cells and axons. However, how m6 A controls regeneration at the whole-organism level remains largely unknown. Here, we demonstrate that the depletion of m6 A methyltransferase regulatory subunit wtap abolishes planarian regeneration, potentially through regulating genes related to cell-cell communication and cell cycle. Single-cell RNA-seq (scRNA-seq) analysis unveils that the wtap knockdown induces a unique type of neural progenitor-like cells (NP-like cells), characterized by specific expression of the cell-cell communication ligand grn. Intriguingly, the depletion of m6 A-modified transcripts grn, cdk9 or cdk7 partially rescues the defective regeneration of planarian caused by wtap knockdown. Overall, our study reveals an indispensable role of m6 A modification in regulating whole-organism regeneration.

Injectable hydrogels for sustained delivery of extracellular vesicles in cartilage regeneration.

Extracellular vesicles (EVs) are a population of small vesicles secreted by essentially all cell types, containing a wide variety of biological macromolecules. Due to their intrinsic capabilities for efficient intercellular communication, they are involved in various aspects of cellular functioning. In the past decade, EVs derived from stem cells attracted interest in the field of regenerative medicine. Owing to their regenerative properties, they have great potential for use in tissue repair, in particular for tissues with limited regenerative capabilities such as cartilage. The maintenance of articular cartilage is dependent on a precarious balance of many different components that can be disrupted by the onset of prevalent rheumatic diseases. However, while cartilage is a tissue with strong mechanical properties that can withstand movement and heavy loads for years, it is virtually incapable of repairing itself after damage has occurred. Stem cell-derived EVs (SC-EVs) transport regenerative components such as proteins and nucleic acids from their parental cells to recipient cells, thereby promoting cartilage healing. Many possible pathways through which SC-EVs execute their regenerative function have been reported, but likely there are still numerous other pathways that are still unknown. This review discusses various preclinical studies investigating intra-articular injections of free SC-EVs, which, while often promoting chondrogenesis and cartilage repair in vivo, showed a recurring limitation of the need for multiple administrations to achieve sufficient tissue regeneration. Potentially, this drawback can be overcome by making use of an EV delivery platform that is capable of sustainably releasing EVs over time. With their remarkable versatility and favourable chemical, biological and mechanical properties, hydrogels can facilitate this release profile by encapsulating EVs in their porous structure. Ideally, the optimal delivery platform can be formed in-situ, by means of an injectable hydrogel that can be administered directly into the affected joint. Relevant research fulfilling these criteria is discussed in detail, including the steps that still need to be taken before injectable hydrogels for sustained delivery of EVs can be applied in the context of cartilage regeneration in the clinic.

Feeding of Hermetia illucens Larvae Meal Attenuates Hepatic Lipid Synthesis and Fatty Liver Development in Obese Zucker Rats.

The present study tested the hypothesis that dietary insect meal from Hermetia illucens (HI) larvae attenuates the development of liver steatosis and hyperlipidemia in the obese Zucker rat. To test the hypothesis, a 4-week trial with male, obese Zucker rats (n = 30) and male, lean Zucker rats (n = 10) was performed. The obese rats were assigned to three obese groups (group O-C, group O-HI25, group O-HI50) of 10 rats each. The lean rats served as a lean control group (L-C). Group L-C and group O-C were fed a control diet with 20% casein as protein source, whereas 25% and 50% of the protein from casein was replaced with protein from HI larvae meal in the diets of group O-HI25 and O-HI50, respectively. The staining of liver sections with Oil red O revealed an excessive lipid accumulation in the liver of group O-C compared to group L-C, whereas liver lipid accumulation in group O-HI25 and O-HI50 was markedly reduced compared to group O-C. Hepatic concentrations of triglycerides, cholesterol, C14:0, C16:0, C16:1, C18:0, C18:1, the sum of total fatty acids and hepatic mRNA levels of several genes associated with lipid synthesis and plasma concentration of cholesterol were markedly higher in group O-C than in group L-C, but lower in group O-HI50 than in group O-C (p < 0.05). In conclusion, partial replacement of casein by HI larvae meal attenuates liver steatosis and dyslipidemia in obese Zucker rats. This suggests that HI larvae meal serves as a functional food protecting from obesity-induced metabolic disorders.

The N-terminal Proline Hinge Motif Controls the Structure of Bovine Herpesvirus 1-encoded Inhibitor of the Transporter Associated with Antigen Processing Required for its Immunomodulatory Function.

Due to unique features, proline residues may control protein structure and function. Here, we investigated the role of 52PPQ54 residues, indicated by the recently established experimental 3D structure of bovine herpesvirus 1-encoded UL49.5 protein as forming a characteristic proline hinge motif in its N-terminal domain. UL49.5 acts as a potent inhibitor of the transporter associated with antigen processing (TAP), which alters the antiviral immune response. Mechanisms employed by UL49.5 to affect TAP remain undetermined on a molecular level. We found that mutations in the 52PPQ54 region had a vast impact on its immunomodulatory function, increasing cell surface MHC class I expression, TAP levels, and peptide transport efficiency. This inhibitory effect was specific for UL49.5 activity towards TAP but not towards the viral glycoprotein M. To get an insight into the impact of proline hinge modifications on structure and dynamics, we performed all-atom and coarse-grained molecular dynamics studies on the native protein and PPQ mutants. The results demonstrated that the proline hinge sequence with its highly rigid conformation served as an anchor into the membrane. This anchor was responsible for the structural and dynamical behavior of the whole protein, constraining the mobility of the C-terminus, increasing the mobility of the transmembrane region, and controlling the accessibility of the C-terminal residues to the cytoplasmic environment. Those features appear crucial for TAP binding and inhibition. Our findings significantly advance the structural understanding of the UL49.5 protein and its functional regions and support the importance of proline motifs for the protein structure.

Factors associated with high-level endurance performance: An expert consensus derived via the Delphi technique.

There is little agreement on the factors influencing endurance performance. Endurance performance often is described by surrogate variables such as maximum oxygen consumption, lactate threshold, and running economy. However, other factors also determine success and progression of high-level endurance athletes. Therefore, the aim was to identify the relevant factors for endurance performance assessed by international experts by adhering to a structured communication method (i.e., Delphi technique). Three anonymous evaluation rounds were conducted initiated by a list of candidate factors (n = 120) serving as baseline input variables. The items that achieved ≥70% of agreement in round 1 were re-evaluated in a second round. Items with a level of agreement of ≥70% in round 2 reached consensus and items with a level of agreement of 40-69% in round 2 were re-rated in a third round followed by a consensus meeting. Round 1 comprised of 27 panellists (n = 24 male) and in round 2 and 3 18 (n = 15 male) of the 27 panellists remained. Thus, the final endurance expert panel comprised of 18 international experts (n = 15 male) with 20 years of experience on average. The consensus report identified the following 26 factors: endurance capacity, running economy, maximal oxygen consumption, recovery speed, carbohydrate metabolism, glycolysis capacity, lactate threshold, fat metabolism, number of erythrocytes, iron deficiency, muscle fibre type, mitochondrial biogenesis, hydrogen ion buffering, testosterone, erythropoietin, cortisol, hydration status, vitamin D deficiency, risk of non-functional overreaching and stress fracture, healing function of skeletal tissue, motivation, stress resistance, confidence, sleep quality, and fatigue. This study provides an expert-derived summary including 26 key factors for endurance performance, the "FENDLE" factors (FENDLE = Factors for ENDurance Level). This consensus report may assist to optimize sophisticated diagnostics, personalized training strategies and technology.

Molecular insights into the mechanism of sugar-modified enkephalin binding to opioid receptors.

Opioid receptors (delta, kappa, and mu) belong to the G protein-coupled receptor (GPCR) superfamily. They are responsible for pain perception - being activated by opioid peptides such as enkephalins, endorphins and dynorphins and by opiates, such as morphine. Enkephalins are naturally occurring endogenous pentapeptides with the amino acid sequence Tyr-Gly-Gly-Phe-Leu/Met. Both enkephalins are potent agonists of the delta receptor, and to a lesser extent the mu receptor, with little to no effect on the kappa receptor. Like most small peptides, enkephalins are easily catabolised via enzymatic degradation and show poor blood-brain barrier penetration. The attachment of sugars to peptides increases their penetration of the blood-brain barrier but also may affect interactions with receptors. In this study, the [Leu5]enkephalin and [Leu5]enkephalin containing the ß-D-glucuronic acid were investigated to explain how the presence of sugar moiety in the peptide molecule influences its interaction with the opioid receptors. In conclusion, the conjugation of an enkephalin molecule with the glucuronic acid has a direct and strong impact on the receptor-ligand interactions. The enhancement of ligand binding is much stronger in the delta receptor than in the mu receptor; thus, enkephalin conjugated with glucuronic acid shows greater selectivity toward the delta opioid receptor than the original peptide.

Retroviral glycoprotein-mediated immune suppression via the potassium channel KCa3.1 - A new strategy for amelioration of inflammatory bowel diseases.

Peptides derived from retroviral envelope proteins have been shown to possess a wide range of immunosuppressive and anti-inflammatory activities. We have previously reported identification of such a peptide derived from the envelope protein coded by a human endogenous retrovirus (HERV). In this study, we identify that in vitro the peptide inhibits the KCa3.1 potassium channel, a potential target for therapy of immune diseases. We describe in vitro ENV59-GP3 effects with respect to potency of inhibition on KCa3.1 channels and calcium influx. Furthermore, we asses in vivo the effect of blocking KCa3.1 with ENV59-GP3 peptide or KCa3.1-blocker NS6180 on protection against DSS-induced acute colitis. ENV59-GP3 peptide treatment showed reduction of the disease score in the DSS-induced acute colitis mice model, which was comparable to effects of the KCa3.1 channel blocker NS6180. Analysis of cytokine production from DSS-mice model treated animals revealed equipotent inhibitory effects of the ENV59-GP3 and NS6180 compounds on the production of IL-6, TNF-α, IL-1ß. These findings altogether suggest that ENV59-GP3 functions as a KCa3.1 channel inhibitor and underline the implications of using virus derived channel blockers for treatment of autoimmune diseases. Additionally, they open the possibilities whether KCa3.1 inhibition is efficacious in patients with inflammatory bowel diseases.