The ISR downstream target ATF4 represses long-term memory in a cell type-specific manner.

The integrated stress response (ISR), a pivotal protein homeostasis network, plays a critical role in the formation of long-term memory (LTM). The precise mechanism by which the ISR controls LTM is not well understood. Here, we report insights into how the ISR modulates the mnemonic process by using targeted deletion of the activating transcription factor 4 (ATF4), a key downstream effector of the ISR, in various neuronal and non-neuronal cell types. We found that the removal of ATF4 from forebrain excitatory neurons (but not from inhibitory neurons, cholinergic neurons, or astrocytes) enhances LTM formation. Furthermore, the deletion of ATF4 in excitatory neurons lowers the threshold for the induction of long-term potentiation, a cellular model for LTM. Transcriptomic and proteomic analyses revealed that ATF4 deletion in excitatory neurons leads to upregulation of components of oxidative phosphorylation pathways, which are critical for ATP production. Thus, we conclude that ATF4 functions as a memory repressor selectively within excitatory neurons.

Near-Barrierless CO Oxidation Using Phosphotungstic Acid-Supported Single-Atom Catalysts.

Efficient CO oxidation at ambient or low temperatures is essential for environmental purification and selective CO oxidation in H2, yet achieving this remains a challenge with current methodologies. In this research, we extensively evaluated the catalytic performance of phosphotungstic acid (PTA)-supported 11 M1/PTA single-atom catalysts (SACs) using density functional theory calculations across both gas phase and 12 common solvents. The Rh1/PTA, Pd1/PTA, and Pt1/PTA systems exhibit moderate CO adsorption energies, facilitating the feasibility of oxygen vacancy formation. Remarkably, the Pd1/PTA and Pt1/PTA catalysts exhibited negligible energy barriers and demonstrated exceptionally high catalytic rates, with values reaching up to (1 × 1010)11, markedly exceeding the threshold for room temperature reactions, set at 6.55 × 108. This phenomenon is attributed to a transition from the high-energy barrier processes of oxygen dissociation in O2 and N-O bond dissociation in N2O to the more efficient dissociation of H2O2. Orbital analysis and charge variations at metal sites throughout the reaction process provide deeper insights into the role of the three metal catalytic sites in CO activation. Our findings not only reveal key aspects of SACs in facilitating CO oxidation at low temperatures but also provide valuable insights for future catalytic reaction mechanism studies and environmental applications.

Gender differences in plasma S100B levels of patients with major depressive disorder.

BACKGROUND: Low concentrations of S100B have neurotrophic effects and can promote nerve growth and repair, which plays an essential role in the pathophysiological and histopathological alterations of major depressive disorder (MDD) during disease development. Studies have shown that plasma S100B levels are altered in patients with MDD. In this study, we investigated whether the plasma S100B levels in MDD differ between genders. METHODS: We studied 235 healthy controls (HCs) (90 males and 145 females) and 185 MDD patients (65 males and 120 females). Plasma S100B levels were detected via multifactor assay. The Mahalanobis distance method was used to detect the outliers of plasma S100B levels in the HC and MDD groups. The Kolmogorov-Smirnov test was used to test the normality of six groups of S100B samples. The Mann-Whitney test and Scheirer-Ray-Hare test were used for the comparison of S100B between diagnoses and genders, and the presence of a relationship between plasma S100B levels and demographic details or clinical traits was assessed using Spearman correlation analysis. RESULTS: All individuals in the HC group had plasma S100B levels that were significantly greater than those in the MDD group. In the MDD group, males presented significantly higher plasma S100B levels than females. In the male group, the plasma S100B levels in the HC group were significantly higher than those in the MDD group, while in the female group, no significant difference was found between the HC and MDD groups. In the male MDD subgroup, there was a positive correlation between plasma S100B levels and years of education. In the female MDD subgroup, there were negative correlations between plasma S100B levels and age and suicidal ideation. CONCLUSIONS: In summary, plasma S100B levels vary with gender and are decreased in MDD patients, which may be related to pathological alterations in glial cells.

Worm Generator: A System for High-Throughput in Vivo Screening.

Large-scale screening of molecules in organisms requires high-throughput and cost-effective evaluating tools during preclinical development. Here, a novel in vivo screening strategy combining hierarchically structured biohybrid triboelectric nanogenerators (HB-TENGs) arrays with computational bioinformatics analysis for high-throughput pharmacological evaluation using Caenorhabditis elegans is described. Unlike the traditional methods for behavioral monitoring of the animals, which are laborious and costly, HB-TENGs with micropillars are designed to efficiently convert animals' behaviors into friction deformation and result in a contact-separation motion between two triboelectric layers to generate electrical outputs. The triboelectric signals are recorded and extracted to various bioinformation for each screened compound. Moreover, the information-rich electrical readouts are successfully demonstrated to be sufficient to predict a drug's identity by multiple-Gaussian-kernels-based machine learning methods. This proposed strategy can be readily applied to various fields and is especially useful in in vivo explorations to accelerate the identification of novel therapeutics.

Identification and Analysis of lncRNA and circRNA Related to Wheat Grain Development.

The role of lncRNA and circRNA in wheat grain development is still unclear. The objectives of this study were to characterize the lncRNA and circRNA in the wheat grain development and to construct the interaction network among lncRNA, circRNA, and their target miRNA to propose a lncRNA-circRNA-miRNA module related to wheat grain development. Full transcriptome sequencing on two wheat varieties (Annong 0942 and Anke 2005) with significant differences in 1000-grain weight at 10 d (days after pollination), 20 d, and 30 d of grain development were conducted. We detected 650, 736, and 609 differentially expressed lncRNA genes, and 769, 1054, and 1062 differentially expressed circRNA genes in the grains of 10 days, 20 days and 30 days after pollination between Annong 0942 and Anke 2005, respectively. An analysis of the lncRNA-miRNA and circRNA-miRNA targeting networks reveals that circRNAs exhibit a more complex and extensive interaction network in the development of cereal grains and the formation of grain shape. Central to these interactions are tae-miR1177, tae-miR1128, and tae-miR1130b-3p. In contrast, lncRNA genes only form a singular network centered around tae-miR1133 and tae-miR5175-5p when comparing between varieties. Further analysis is conducted on the underlying genes of all target miRNAs, we identified TaNF-YB1 targeted by tae-miR1122a and TaTGW-7B targeted by miR1130a as two pivotal regulatory genes in the development of wheat grains. The quantitative real-time PCR (qRT-PCR) and dual-luciferase reporter assays confirmed the target regulatory relationships between miR1130a-TaTGW-7B and miR1122a-TaNF-YB1. We propose a network of circRNA and miRNA-mediated gene regulation in the development of wheat grains.

First principles calculation of the ZnV2O6(001) surface terminations: the thermodynamic stability and electronic structure study.

We have investigated the surface structure and relative stability of ZnV2O6(001) using a thermodynamic technique based on density functional theory (DFT). We built Zn-V-O surface phase diagrams of various surface terminations using the obtained surface Gibbs free energy. In this study, we selected nine different surface terminations along the (001) crystal plane to elucidate that the E, G, H, and I terminations (as shown in Table 1) are the most stable configurations. We found that although their stability varies widely, the four terminations on the ZnV2O6(001) surface can be stabilized under specific thermodynamic equilibrium circumstances. Furthermore, we calculated the surface electronic structures of the four surface terminations and found that there are surface states conducive to visible light absorption at the G, H, and I terminations. The different termination structures are significant in improving the range and intensity of light absorption of ZnV2O6 in specific regions. The fact that the work functions fluctuate significantly for different surface terminations suggests that the work function of ZnV2O6 can be changed to increase photocatalytic activity by achieving thermodynamically favored surface terminations under appropriate conditions. The obtained surface phase diagram will further lay a foundation for the study of the ZnV2O6 surface. These results may help to explore the inherent properties of the ZnV2O6 surface and provide useful strategies for future experimental research on ZnV2O6-based photocatalysts.

FZD7, Regulated by Non-CpG Methylation, Plays an Important Role in Immature Porcine Sertoli Cell Proliferation.

The regulatory role of non-CpG methylation in mammals has been important in whole-genome bisulfite sequencing. It has also been suggested that non-CpG methylation regulates gene expression to affect the development and health of mammals. However, the dynamic regulatory mechanisms of genome-wide, non-CpG methylation during testicular development still require intensive study. In this study, we analyzed the dataset from the whole-genome bisulfite sequencing (WGBS) and the RNA-seq of precocious porcine testicular tissues across two developmental stages (1 and 75 days old) in order to explore the regulatory roles of non-CpG methylation. Our results showed that genes regulated by non-CpG methylation affect the development of testes in multiple pathways. Furthermore, several hub genes that are regulated by non-CpG methylation during testicular development-such as VEGFA, PECAM1, and FZD7-were also identified. We also found that the relative expression of FZD7 was downregulated by the zebularine-induced demethylation of the first exon of FZD7. This regulatory relationship was consistent with the results of the WGBS and RNA-seq analysis. The immature porcine Sertoli cells were transfected with RNAi to mimic the expression patterns of FZD7 during testicular development. The results of the simulation test showed that cell proliferation was significantly impeded and that cell cycle arrest at the G2 phase was caused by the siRNA-induced FZD7 inhibition. We also found that the percentage of early apoptotic Sertoli cells was decreased by transfecting them with the RNAi for FZD7. This indicates that FZD7 is an important factor in linking the proliferation and apoptosis of Sertoli cells. We further demonstrated that Sertoli cells that were treated with the medium collected from apoptotic cells could stimulate proliferation. These findings will contribute to the exploration of the regulatory mechanisms of non-CpG methylation in testicular development and of the relationship between the proliferation and apoptosis of normal somatic cells.

Comprehensive Analysis of the Transcriptome-Wide m6A Methylome in Shaziling Pig Testicular Development.

RNA N6-methyladenosine (m6A) modification is one of the principal post-transcriptional modifications and plays a dynamic role in testicular development and spermatogenesis. However, the role of m6A in porcine testis is understudied. Here, we performed a comprehensive analysis of the m6A transcriptome-wide profile in Shaziling pig testes at birth, puberty, and maturity. We analyzed the total transcriptome m6A profile and found that the m6A patterns were highly distinct in terms of the modification of the transcriptomes during porcine testis development. We found that key m6A methylated genes (AURKC, OVOL, SOX8, ACVR2A, and SPATA46) were highly enriched during spermatogenesis and identified in spermatogenesis-related KEGG pathways, including Wnt, cAMP, mTOR, AMPK, PI3K-Akt, and spliceosome. Our findings indicated that m6A methylations are involved in the complex yet well-organized post-transcriptional regulation of porcine testicular development and spermatogenesis. We found that the m6A eraser ALKBH5 negatively regulated the proliferation of immature porcine Sertoli cells. Furthermore, we proposed a novel mechanism of m6A modification during testicular development: ALKBH5 regulated the RNA methylation level and gene expression of SOX9 mRNA. In addition to serving as a potential target for improving boar reproduction, our findings contributed to the further understanding of the regulation of m6A modifications in male reproduction.

Nursing students' experiences of workplace violence based on the perspective of gender differences: a phenomenological study.

BACKGROUND: Workplace violence is a worldwide concern, and particularly affects nursing students. It has a seriously negative impact on nursing students' clinical learning experience and their physical and mental health. This study explored whether there are differences in psychological responses and coping styles among different gender nursing students after exposure to workplace violence, and investigated the causes for these differences. METHODS: We enrolled 22 nursing undergraduates from Guangzhou Medical University and Zunyi Medical University, China. Phenomenological qualitative research and online semi-structured interviews were conducted. The data were analyzed by the Colaizzi seven-step content analysis method. RESULTS: Two categories were collated: psychological experience and coping styles. Three themes of the former were extracted: negative emotional experience, low level of professional identity, and negative effect on self-efficacy. Two themes of the latter: responses to violence and adjustment after violence. In addition, fourteen subthemes were extracted. CONCLUSIONS: Different gender nursing students have different psychological experience and coping styles in the face of workplace violence. The causes of the differences are likely related to sociocultural factors and psychological gender status.

Injectable Black Phosphorus Nanosheets for Wireless Nongenetic Neural Stimulation.

Neurons can be modified to express light-sensitive proteins for enabling stimulation with a high spatial and temporal resolution, but such techniques require gene transfection and systematical implantation. Here, a black phosphorus nanosheet-based injectable strategy is described for wireless neural stimulation both in vitro and in vivo without cell modifications. These nanosheets, with minimal invasiveness, high biocompatibility, and biodegradability, are anchored on cell membranes as miniature near-infrared (NIR) light transducers to create local heating for neural activity excitation. Based on cultured multielectrode-array recording, in vivo electrophysiology analysis, and open field behavioral tests, it is demonstrated that remotely applied NIR illumination can reliably trigger spiking activity in cultured neurons and rat brains. Excitingly, reliable regulation of brain function to control animal behaviors is also described. Moreover, this approach has shown its potential for future clinical use by successful high-frequency stimulation in cells and animals in this proof-of-concept study. It is believed that this new method will offer a powerful alternative to other neural stimulation solutions and potentially be of independent value to the healthcare system.

N6-Methyladenosine dynamic changes and differential methylation in wheat grain development.

MAIN CONCLUSION: More methylation changes occur in late interval than in early interval of wheat seed development with protein and the starch synthesis-related pathway enriched in the later stages. Wheat seed development is a critical process to determining wheat yield and quality, which is controlled by genetics, epigenetics and environments. The N6-methyladenosine (m6A) modification is a reversible and dynamic process and plays regulatory role in plant development and stress responses. To better understand the role of m6A in wheat grain development, we characterized the m6A modification at 10 day post-anthesis (DPA), 20 DPA and 30 DPA in wheat grain development. m6A-seq identified 30,615, 30,326, 27,676 high confidence m6A peaks from the 10DPA, 20DPA, and 30DPA, respectively, and enriched at 3'UTR. There were 29,964, 29,542 and 26,834 unique peaks identified in AN0942_10d, AN0942_20d and AN0942_30d. One hundred and forty-two genes were methylated by m6A throughout seed development, 940 genes methylated in early grain development (AN0942_20d vs AN0942_10d), 1542 genes in late grain development (AN0942_30d vs AN0942_20d), and 1190 genes between early and late development stage (AN0942_30d vs AN0942_10d). KEGG enrichment analysis found that protein-related pathways and the starch synthesis-related pathway were significantly enriched in the later stages of seed development. Our results provide novel knowledge on m6A dynamic changes and its roles in wheat grain development.

Interfacial Effect on Dielectric Properties of Self-Assembled Polythiourea-Based Copolymers for Ultrahigh Energy Storage.

Polymer dielectrics are highly desirable in capacitor applications due to their low cost, high stability, and reliability. However, there still remains a lack of feasible methods to prepare polymer dielectrics with high energy density and low dielectric loss, which severely hampers the development of compact and efficient power electronics. Here, an amphiphilic block copolymer, polythiourea-b-polydimethylsiloxane (PTU-b-PDMS), with an extraordinarily high energy density of 29.8 J cm-3 and a low loss is synthesized via polyaddition polymerization. This is highly relevant to the block molecule conformation in the interfacial region of the self-assembled PTU-b-PDMS. The block molecule in the interface adopts an extended conformation when the PTU forms nanodots, whereas the block molecule adopts a coiled conformation when the PTU forms nanostrands. The observation and characterization have proved that the coiled block molecule in the interfacial region can simultaneously induce extra strong charge trapping sites and dipolar polarization. It substantially improves the breakdown strength from 652 to 1166 MV m-1 , while maintaining a high dielectric constant of 5 and a low loss of <0.01. This work offers unprecedented structural insights into the conformation-induced interfacial effect and enables rational design of self-assembled copolymers to boost their dielectric properties and energy density.

Alternating Current Electrolysis Enabled Formal C-O/O-H Cross-Metathesis of 4-Alkoxy Anilines with Alcohols.

While multiple bond metathesis reactions, for example olefin metathesis, have seen considerable recent progress, direct metathesis of traditionally inert C-O single bonds is extremely rare and particularly challenging. Undoubtedly, metathesis reaction of C-O bonds is one of the most ideal routes for the value-added upgrading of molecules involving C-O bonds. Reported here is a new protocol to achieve the formal C-O/O-H cross-metathesis via alternating current electrolysis. Featuring mild reaction conditions, the protocol allows readily available 4-alkoxy anilines and alcohols to be converted into a wide range of valuable products in highly regioselective and chemoselective manner. Moreover, the present strategy can be used in the late-stage modification of pharmaceuticals as well as biologically active compounds, which demonstrated the potential application.

miR-130a promotes immature porcine Sertoli cell growth by activating SMAD5 through the TGF-ß-PI3K/AKT signaling pathway.

Sertoli cells play vital roles in normal spermatogenesis, and microRNAs (miRNAs) participate in regulating Sertoli cell development. However, the functions and mechanisms of action of most identified miRNAs in porcine Sertoli cells remain largely unknown. Herein, we primarily explored the regulatory roles of miR-130a in immature porcine Sertoli cells using EdU-based high-content screening assay. The results demonstrated that 27 miRNAs have potential roles in the promotion of immature porcine Sertoli cell proliferation, and miR-130a was identified as a promising candidate. miR-130a promoted cell cycle progression and cell proliferation, whereas it impeded cell apoptosis in immature porcine Sertoli cells. It also contributed to Sertoli cell proliferation and testis development in vivo. A TMT-based proteomics approach revealed that miR-130a regulated the expression of 91 proteins and multiple pathways, including the TGF-ß and PI3K/AKT signaling. miR-130a did not directly target the 3'-UTR of SMAD5; however, it increased SMAD5 phosphorylation. Moreover, miR-130a enhanced TGF-ß signaling by activating SMAD5 protein, and TGF-ß signaling further activated the PI3K/AKT signaling pathway to promote cell proliferation and inhibit cell apoptosis in porcine immature Sertoli cells. Collectively, miR-130a promoted immature porcine Sertoli cell growth by activating SMAD5 through the TGF-ß-PI3K/AKT signaling pathway. This study, therefore, provides novel insights into the effects of miR-130a on porcine spermatogenesis through the regulation of immature Sertoli cell proliferation and apoptosis.

The role of polysaccharides functional groups in cadmium binding in root cell wall of a cadmium-safe rice line.

Exploring the mechanism of cadmium (Cd) accumulation in Cd-safe rice lines is beneficial for ensuring rice safety. D62B, a Cd-safe rice line, accumulates less than 0.2 mg Cd kg-1 in the brown rice due to strong capacity of Cd retention in the roots, and the root cell wall (RCW) polysaccharides play important roles. However, specific underlying mechanism of Cd binding on the polysaccharides is little known. In this study, the role of polysaccharides, especially pectin and hemicellulose 1 (HC1), in RCW of D62B was investigated by adsorption experiments and Fourier Transform Infrared Spectroscopy (FTIR) analysis compared with a common rice line (Luhui17). Cadmium was adsorbed on RCW of two rice lines by a multilayer and inhomogeneous chemisorption way with the force of ion transfer or exchange. Cadmium was adsorbed on RCW rapidly at first stage with the limit of internal and external diffusion, and gradually reached saturation. With the removal of pectin, the Cd adsorption rate, maximum Cd adsorption amount and the shift degree of carboxyl groups in the RCW of D62B sharply decreased, which showed advantages compared with Luhui17. Sequential removal of HC1 further decreased the maximum Cd adsorption amount and the shift degree of hydroxyl groups. The results showed that more available functional groups, especially carboxyl groups in pectin and hydroxyl groups in HC1, contributed to Cd immobilization within the RCW of Cd-safe rice line, thus limiting Cd translocation to the shoot and reducing Cd accumulation in the brown rice.

miR-499 promotes immature porcine Sertoli cell growth through the PI3K/AKT pathway by targeting the PTEN gene.

Sertoli cells are indispensable for normal spermatogenesis, and increasing evidence has shown that miRNAs participate in the regulation of Sertoli cell growth. However, the functions and regulatory mechanisms of miRNAs in Sertoli cells of domestic animals have not been fully investigated. In the present study, we mainly investigated the regulatory roles of miR-499 in immature porcine Sertoli cells. The results showed that miR-499 was mainly located in the basement section of seminiferous tubules of prepubertal porcine testicular tissue. Overexpression of miR-499 promoted cell proliferation and inhibited apoptosis, whereas miR-499 inhibition resulted in the opposite effect. The PTEN gene was directly targeted by miR-499, and the expression of mRNA and protein was also negatively regulated by miR-499 in immature porcine Sertoli cells. siRNA-induced PTEN knockdown resulted in a similar effect as an overexpression of miR-499 and abolished the effects of miR-499 inhibition on immature porcine Sertoli cells. Moreover, both miR-499 overexpression and the PTEN knockdown activated the PI3K/AKT signaling pathway, whereas inhibition of the PI3K/AKT signaling pathway caused immature porcine Sertoli cell apoptosis and inhibited cell proliferation. Overall, miR-499 promotes proliferation and inhibits apoptosis in immature porcine Sertoli cells through the PI3K/AKT pathway by targeting the PTEN gene. This study provides novel insights into the effects of miR-499 in spermatogenesis through the regulation of immature Sertoli cell proliferation and apoptosis.

The application of genomic selection in pig cross breeding.

Genomic selection is a form of marker-assisted selection in which genetic markers covering the entire genome are used so that all quantitative trait loci are in linkage disequilibrium with at least one marker. Genomic selection improves the efficiency and accuracy of breeding and it is widely used in purebred breeding across many animal species. However, some studies indicate that the accuracy of genome selection in cross breeding needs to be improved,especially in cross population. As one of the most extensive breeding methods employed in the swine industry, cross breeding has significant, potential research and economic value to further improve its performance by combining with genomic selection. In this review, we summarize the application of genomic selection in pigs, and elucidate the genomic selection deficiencies in breeding hybrid pigs. This review will also provide valuable insights for the future application and improvement of genomic selection in pig cross breeding.

Validation, Identification, and Biological Consequences of the Site-specific O-GlcNAcylation Dynamics of Carbohydrate-responsive Element-binding Protein (ChREBP).

O-GlcNAcylation of carbohydrate-responsive element-binding protein (ChREBP) is believed as an important modulator of ChREBP activities, however little direct evidence of O-GlcNAcylation on ChREBP and no exact O-GlcNAcylation sites have been reported so far. Here, we validate O-GlcNAcylation on ChREBP in cell-free coupled transcription/translation system and in cells by chemoenzymatic and metabolic labeling, respectively. Moreover, for the first time, we identify O-GlcNAcylation on Ser614 in the C-terminus of ChREBP by mass spectrometry and validate two important sites, Thr517 and Ser839 for O-GlcNAcylation and their function via molecular and chemical biological method. Under high glucose conditions, Ser514 phosphorylation enhances ChREBP O-GlcNAcylation, maintaining the transcriptional activity of ChREBP; Ser839 O-GlcNAcylation is essential for Mlx-heterodimerization and DNA-binding activity enhancement, consequently inducing transcriptional activity. Ser839 O-GlcNAcylation is also crucial for ChREBP nuclear export partially by strengthening interactions with CRM1 and 14-3-3. This work is a detailed study of ChREBP O-GlcNAcylation and highlights the biological consequences of the site-specific O-GlcNAcylation dynamics of ChREBP.

Interference with NTSR1 Expression Exerts an Anti-Invasion Effect via the Jun/miR-494/SOCS6 Axis of Glioblastoma Cells.

BACKGROUND/AIMS: Glioblastoma is the most common and aggressive brain tumor and carries a poor prognosis. Previously, we found that neurotensin receptor 1 (NTSR1) contributes to glioma progression, but the underlying mechanisms of NTSR1 in glioblastoma invasion remain to be clarified. The aim of this study was to investigate the molecular mechanisms of NTSR1 in glioblastoma invasion. METHODS: Cell migration and invasion were evaluated using wound-healing and transwell assays. Cell proliferation was detected using CCK-8. The expression of NTSR1, Jun, and suppressor of cytokine signaling 6 (SOCS6) was detected using western blotting. The expression of miR-494 was detected by Quantitative real-time PCR. Chromatin immunoprecipitation assay was performed to examine the interaction between Jun and miR-494 promoter. Dual-luciferase reporter assay and western blotting were performed to identify the direct regulation of SOCS6 by miR-494. An orthotopic xenograft mouse model was conducted to assess tumor growth and invasion. RESULTS: NTSR1 knockdown attenuated the invasion of glioblastoma cells. Jun was positively regulated by NTSR1, which promoted miR-494 expression through binding to miR-494 promoter. SOCS6 was confirmed as a direct target of miR-494, thus, NTSR1-induced miR-494 upregulation resulted in SOCS6 downregulation. Both miR-494 and SOCS6 were involved in the NTSR1-induced invasion of glioblastoma cells. In vivo, tumor invasion and growth were inhibited by NTSR1 knockdown, but were restored with miR-494 overexpression. CONCLUSION: NTSR1 knockdown inhibited glioblastoma invasion via the Jun/miR-494/SOCS6 axis.

A new GLP-1 analogue with prolonged glucose-lowering activity in vivo via backbone-based modification at the N-terminus.

Glucagon-like peptide-1 (GLP-1) is an endogenous insulinotropic hormone with wonderful glucose-lowering activity. However, its clinical use in type II diabetes is limited due to its rapid degradation at the N-terminus by dipeptidyl peptidase IV (DPP-IV). Among the N-terminal modifications of GLP-1, backbone-based modification was rarely reported. Herein, we employed two backbone-based strategies to modify the N-terminus of tGLP-1. Firstly, the amide N-methylated analogues 2-6 were designed and synthesized to make a full screening of the N-terminal amide bonds, and the loss of GLP-1 receptor (GLP-1R) activation indicated the importance of amide H-bonds. Secondly, with retaining the N-terminal amide H-bonds, the ß-peptide replacement strategy was used and analogues 7-13 were synthesized. By two rounds of screening, analogue 10 was identified. Analogue 10 greatly improved the DPP-IV resistance with maintaining good GLP-1R activation in vitro, and showed approximately a 4-fold prolonged blood glucose-lowering activity in vivo in comparison with tGLP-1. This modification strategy will benefit the development of GLP-1-based anti-diabetic drugs.