Controlled Reversible N-Terminal Modification of Peptides and Proteins.

A reversible modification strategy enables a switchable cage/decage process of proteins with an array of applications for protein function research. However, general N-terminal selective reversible modification strategies which present site selectivity are specifically limited. Herein, we report a general reversible modification strategy compatible with 20 canonical amino acids at the N-terminal site by the palladium-catalyzed cinnamylation of native peptides and proteins under biologically relevant conditions. This approach broadens the substrate adaptability of N-terminal modification of proteins and shows a potential impact on the more challenging protein substrates such as antibodies. In the presence of 1,3-dimethylbarbituric acid, palladium-catalyzed deconjugation released native peptides and proteins efficiently. Harnessing the reversible nature of this protocol, practical applications were demonstrated by precise function modulation of antibodies and traceless enrichment of the protein-of-interest for proteomics analysis. This novel on/off strategy working on the N-terminus will provide new opportunities in chemical biology and medicinal research.

Serum cytokine biosignatures for identification of tuberculosis among HIV-positive inpatients.

BACKGROUND: Serum cytokines correlate with tuberculosis (TB) progression and are predictors of TB recurrence in people living with HIV. We investigated whether serum cytokine biosignatures could diagnose TB among HIV-positive inpatients. METHODS: We recruited HIV-positive inpatients with symptoms of TB and measured serum levels of inflammation biomarkers including IL-2, IL-4, IL-6, IL-10, tumour necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ). We then built and tested our TB prediction model. RESULTS: 236 HIV-positive inpatients were enrolled in the first cohort and all the inflammation biomarkers were significantly higher in participants with microbiologically confirmed TB than those without TB. A binary support vector machine (SVM) model was built, incorporating the data of four biomarkers (IL-6, IL-10, TNF-α and IFN-γ). Efficacy of the SVM model was assessed in training (n=189) and validation (n=47) sets with area under the curve (AUC) of 0.92 (95% CI 0.88 to 0.96) and 0.85 (95% CI 0.72 to 0.97), respectively. In an independent test set (n=110), the SVM model yielded an AUC of 0.85 (95% CI 0.76 to 0.94) with 78% (95% CI 68% to 87%) specificity and 85% (95% CI 66% to 96%) sensitivity. Moreover, the SVM model outperformed interferon-gamma release assay (IGRA) among advanced HIV-positive inpatients irrespective of CD4+ T-cell counts, which may be an alternative approach for identifying Mycobacterium tuberculosis infection among HIV-positive inpatients with negative IGRA. CONCLUSIONS: The four-cytokine biosignature model successfully identified TB among HIV-positive inpatients. This diagnostic model may be an alternative approach to diagnose TB in advanced HIV-positive inpatients with low CD4+ T-cell counts.

Design and synthesis of novel site-specific antibody-drug conjugates that target TROP2.

The approval of Trodelvy® validates TROP2 as a druggable but challenging target for antibody-drug conjugates (ADCs) to treat metastatic triple-negative breast cancer (mTNBC). Here, based on the TROP2-targeted antibody sacituzumab, we designed and developed several site-specific ADC candidates, which employ MMAE (monomethyl auristatin E) as the toxin, via IgG glycoengineering or affinity-directed traceless conjugation. Systematic evaluation of these site-specific ADCs in homogeneity, hydrophilicity, stability, and antitumor efficiency was conducted. The results indicate that the site-specific ADCs gsADC 3b made from one-step glycoengineering exhibit good aggregation stability and in vivo efficacy, providing a new format of ADCs that target TROP2.

The effects of the renin inhibitor aliskiren on neuronal toxic damage.

The neurotoxicity of amyloid-ß (Aß) and its deposition in neurons plays a critical role in the occurrence and development of Alzheimer's disease (AD). Several preclinical experiments have found that the renin inhibitor aliskiren has a wide range of physiological effects, including hindering the progression of atherosclerosis and anti-inflammatory. This study is aimed to explore the effect of aliskiren on neuronal toxic damage and the underlying mechanism. This study established an in vitro nerve injury model through Aß 1-42 induction; the effects of aliskiren on the viability, inflammatory damage and apoptosis of SH-SY5Y cells were examined. For the sake of explore the underlying mechanism; SwissTargetPrediction website and molecular docking were utilized to predict the target of aliskiren. Then the impacts of the target protein overexpression were determined to verify its mediation. The results of the current study demonstrate that aliskiren has no effect on the viability of SH-SY5Y cells while Aß1-42accumulation could significantly downregulate cell viability. In addition, aliskiren could alleviate neuronal inflammatory damage and apoptosis arise from Aß 1-42accumulation. Following confirming the high expression level of the predicted target PDE4B in damaged cells, it was found that PDE4B overexpression can reverse the influence of aliskiren on cell viability, inflammatory damage and apoptosis. In conclusion, aliskiren upregulates cell viability, reduces inflammatory damage and apoptosis induced by Aß accumulation in AD via inhibiting PDE4B. These findings have expanded the scope of future application of aliskiren and provided a theoretical basis.

Progression predictors of clinically isolated syndrome to multiple sclerosis: A prospective study in China.

OBJECTIVES: Clinically isolated syndrome (CIS) is a preclinical phase of multiple sclerosis (MS). The progression rate of CIS to clinical definite MS (CDMS) varies significantly across different populations, and identifying predictors of progression is crucial for early diagnosis and treatment. We aimed to investigate predictors of progression from CIS to CDMS in a Chinese cohort. METHODS: A single-center cohort study was conducted with newly diagnosed patients with CIS in China between 2018 and 2021. All patients underwent a comprehensive clinical evaluation, including neurological examination, magnetic resonance imaging, and laboratory tests. Follow-up assessments were conducted at regular intervals to monitor disease progression. Progression to CDMS was defined according to the 2017 McDonald criteria. Age, sex, Expanded Disability Status Scale (EDSS) score, number of patients with magnetic resonance imaging gadolinium-enhancing (Gd+) lesions, T2 lesions and Gd+ lesions count, CSF cell count, CSF total protein, CSF and serum neurofilament light chain (NfL), progranulin (PGRN) and Th17-related cytokines (IL-6, IL-17, IL-21, IL-22, IL-23 and TGF-ß) were measured for association with risk of progression to CDMS. RESULTS: A total of 96 CIS patients were recruited in the study. During the at least 24 months follow-up period, 57 (59.38 %) CIS patients progressed to CDMS, while 39 (40.62 %) patients without progression remained stable as CIS. Multivariate analysis revealed that younger age at onset (OR= 43.43, 95 % CI= 1.76-1071.68, p<0.021), higher CSF elevated protein (OR=58.64, 95 % CI=2.72-1264.51, p=0.009), higher CSF NfL levels (OR= 97.00, 95 % CI= 4.68-2012.99, p=0.003) and higher CSF IL-23 levels (OR= 412.02, 95 % CI=6.56-25869.60, p=0.004) were associated with high risk of progression to CDMS. CONCLUSION: Younger age at onset, elevated CSF NfL, IL-23 and protein levels might be progression predictors of CIS to CDMS in Chinese population.

Neurotransmitter metabolites in milk ferments of Leuconostoc mesenteroides regulate temperature-sensitive heartbeats in an ex ovo model.

Accumulated evidence has supported the probiotic activity of Leuconostoc mesenteroides (L. mesenteroides) which can yield beneficial metabolites via fermentation. Here, bovine milk rich in phenylalanine（PHE) was used as a source for fermentation of L. mesenteroides. The complexes of PHE with bacterial phenylalanine hydroxylase (PheH) at two temperatures were revealed via molecular dynamics simulation. Two carbon hydrogen bonds and a Pi-Alkyl T-shaped interaction were newly formed at an active site of the PheH-PHE complex. The PheH interacted with two different hydrogen atoms in an amine of PHE via conventional hydrogen bonds at 37 °C, a temperature that accelerated the milk fermentation of L. mesenteroides. Twenty-eight metabolites including various neurotransmitters in fermented milk were identified and quantified by liquid chromatography coupled to quadrupole ion trap (Q-Trap) tandem mass spectrometry. Ex ovo injection of milk ferments into the yolk sac of chicken embryos enhanced a rising temperature-induced increase in heartbeats towards the normal resting level. The neurotransmitter-rich milk ferments hold potential for using to adjust energy metabolism, referred from heart rates, during fluctuating temperature conditions.

The role of USP7-YY1 interaction in promoting colorectal cancer growth and metastasis.

Colorectal cancer (CRC) remains a significant global health issue with high incidence and mortality. Yin Yang 1 (YY1) is a powerful transcription factor that acts dual roles in gene activation and repression. High expression level of YY1 has been reported in CRC, indicating the existence of stable factors of YY1 in CRC cells. We aimed to identify the key molecules and underlying mechanisms responsible for stabilizing YY1 expression in CRC. Mass spectrometry analysis was utilized to identify USP7 as a potential molecule that interacted with YY1. Mechanically, USP7 stabilizes YY1 expression at the protein level by interfering its K63 linkage ubiquitination. YY1 exerts its oncogenic function through transcriptionally activating TRIAP1 but suppressing LC3B. In addition, at the pathological level, there is a positive correlation between the expression of YY1 and the budding of CRC. This study has revealed the intricate interplay between YY1 and USP7 in CRC, suggesting that they could serve as novel therapeutic targets or predictive biomarkers for CRC patients.

Phosphorylated FOXQ1, a novel substrate of JNK1, inhibits sorafenib-induced ferroptosis by activating ETHE1 in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a highly heterogeneous and malignant cancer with poor overall survival. The application of sorafenib is a major breakthrough in the treatment of HCC. In our study, FOXQ1 was significantly overexpressed in sorafenib-resistant HCC cells and suppressed sorafenib-induced ferroptosis. We found that phosphorylation of FOXQ1 at serine 248 is critical for the suppression of sorafenib-induced ferroptosis. Furthermore, as the upstream phosphorylation kinase of FOXQ1, JNK1, which is activated by sorafenib, can directly phosphorylate the serine 248 site of FOXQ1. Then, the phosphorylated FOXQ1 got a high affinity for the promoter of ETHE1 and activates its transcription. Further flow cytometry results showed that ETHE1 reduced intracellular lipid peroxidation and iron levels. Collectively, our study implicated the JNK1-FOXQ1-ETHE1 axis in HCC ferroptosis induced by sorafenib, providing mechanistic insight into sensitivity to sorafenib therapy of HCC.

Single-Nucleus Landscape of Glial Cells and Neurons in Alzheimer's Disease.

Alzheimer's disease (AD) is a neurodegenerative disease with a projected significant increase in incidence. Therefore, this study analyzed single-nucleus AD data to provide a theoretical basis for the clinical development and treatment of AD. We downloaded AD-related monocyte data from the Gene Expression Omnibus database, annotated cells, compared cell abundance between groups, and investigated glial and neuronal cell biological processes and pathways through functional enrichment analysis. Furthermore, we constructed a global regulatory network for AD based on cell communication and ecological analyses. Our findings revealed increased abundance of Capping Protein Regulator And Myosin 1 linker 1 (CARMIL1)+ astrocytes (AST), Immunoglobulin Superfamily Member 21 (IGSF21)+ microglia (MIC), SRY-Box Transcription Factor 6 (SOX6)+ inhibitory neurons (InNeu), and laminin alpha-2 chain (LAMA2)+ oligodendrocytes (OLI) cell subgroups in tissues of patients with AD, while prostaglandin D2 synthase (PTGDS)+ AST, Src Family Tyrosine Kinase (FYN)+ MIC, and Proteolipid Protein 1 (PLP1)+ InNeu subgroups specifically decreased. We found that the cell phenotype of patients with AD shifted from a simpler to a more complex state compared to the control group. Cell communication analysis revealed strong communication between MIC and NEU. Furthermore, AST, MIC, NEU, and OLI were involved in oxidative stress- and inflammation-related pathways, potentially contributing to disease development. This study provides a theoretical basis for further exploring the specific mechanisms underlying AD.

Exploration of novel biomarkers in Alzheimer's disease based on four diagnostic models.

Background: Despite tremendous progress in diagnosis and prediction of Alzheimer's disease (AD), the absence of treatments implies the need for further research. In this study, we screened AD biomarkers by comparing expression profiles of AD and control tissue samples and used various models to identify potential biomarkers. We further explored immune cells associated with these biomarkers that are involved in the brain microenvironment. Methods: By differential expression analysis, we identified differentially expressed genes (DEGs) of four datasets (GSE125583, GSE118553, GSE5281, GSE122063), and common expression direction of genes of four datasets were considered as intersecting DEGs, which were used to perform enrichment analysis. We then screened the intersecting pathways between the pathways identified by enrichment analysis. DEGs in intersecting pathways that had an area under the curve (AUC) > 0.7 constructed random forest, least absolute shrinkage and selection operator (LASSO), logistic regression, and gradient boosting machine models. Subsequently, using receiver operating characteristic curve (ROC) and decision curve analysis (DCA) to select an optimal diagnostic model, we obtained the feature genes. Feature genes that were regulated by differentially expressed miRNAs (AUC > 0.85) were explored further. Furthermore, using single-sample GSEA to calculate infiltration of immune cells in AD patients. Results: Screened 1855 intersecting DEGs that were involved in RAS and AMPK signaling. The LASSO model performed best among the four models. Thus, it was used as the optimal diagnostic model for ROC and DCA analyses. This obtained eight feature genes, including ATP2B3, BDNF, DVL2, ITGA10, SLC6A12, SMAD4, SST, and TPI1. SLC6A12 is regulated by miR-3176. Finally, the results of ssGSEA indicated dendritic cells and plasmacytoid dendritic cells were highly infiltrated in AD patients. Conclusion: The LASSO model is the optimal diagnostic model for identifying feature genes as potential AD biomarkers, which can supply new strategies for the treatment of patients with AD.

C-terminal modification and functionalization of proteins via a self-cleavage tag triggered by a small molecule.

The precise modification or functionalization of the protein C-terminus is essential but full of challenges. Herein, a chemical approach to modify the C-terminus is developed by fusing a cysteine protease domain on the C-terminus of the protein of interest, which could achieve the non-enzymatic C-terminal functionalization by InsP6-triggered cysteine protease domain self-cleavage. This method demonstrates a highly efficient way to achieve protein C-terminal functionalization and is compatible with a wide range of amine-containing molecules and proteins. Additionally, a reversible C-terminal de-functionalization is found by incubating the C-terminal modified proteins with cysteine protease domain and InsP6, providing a tool for protein functionalization and de-functionalization. Last, various applications of protein C-terminal functionalization are provided in this work, as demonstrated by the site-specific assembly of nanobody drug conjugates, the construction of a bifunctional antibody, the C-terminal fluorescent labeling, and the C-terminal transpeptidation and glycosylation.

The Integrative and Conjugative Element ICECspPOL2 Contributes to the Outbreak of Multi-Antibiotic-Resistant Bacteria for Chryseobacterium Spp. and Elizabethkingia Spp.

Antibiotic resistance genes (ARGs) and horizontal transfer of ARGs among bacterial species in the environment can have serious clinical implications as such transfers can lead to disease outbreaks from multidrug-resistant (MDR) bacteria. Infections due to antibiotic-resistant Chryseobacterium and Elizabethkingia in intensive care units have been increasing in recent years. In this study, the multi-antibiotic-resistant strain Chryseobacterium sp. POL2 was isolated from the wastewater of a livestock farm. Whole-genome sequencing and annotation revealed that the POL2 genome encodes dozens of ARGs. The integrative and conjugative element (ICE) ICECspPOL2, which encodes ARGs associated with four types of antibiotics, including carbapenem, was identified in the POL2 genome, and phylogenetic affiliation analysis suggested that ICECspPOL2 evolved from related ICEEas of Elizabethkingia spp. Conjugation assays verified that ICECspPOL2 can horizontally transfer to Elizabethkingia species, suggesting that ICECspPOL2 contributes to the dissemination of multiple ARGs among Chryseobacterium spp. and Elizabethkingia spp. Because Elizabethkingia spp. is associated with clinically significant infections and high mortality, there would be challenges to clinical treatment if these bacteria acquire ICECspPOL2 with its multiple ARGs, especially the carbapenem resistance gene. Therefore, the results of this study support the need for monitoring the dissemination of this type of ICE in Chryseobacterium and Elizabethkingia strains to prevent further outbreaks of MDR bacteria. IMPORTANCE Infections with multiple antibiotic-resistant Chryseobacterium and Elizabethkingia in intensive care units have been increasing in recent years. In this study, the mobile integrative and conjugative element ICECspPOL2, which was associated with the transmission of a carbapenem resistance gene, was identified in the genome of the multi-antibiotic-resistant strain Chryseobacterium sp. POL2. ICECspPOL2 is closely related to the ICEEas from Elizabethkingia species, and ICECspPOL2 can horizontally transfer to Elizabethkingia species with the tRNA-Glu-TTC gene as the insertion site. Because Elizabethkingia species are associated with clinically significant infections and high mortality, the ability of ICECspPOL2 to transfer carbapenem resistance from environmental strains of Chryseobacterium to Elizabethkingia is of clinical concern.

miR-34a knockout attenuates cognitive deficits in APP/PS1 mice through inhibition of the amyloidogenic processing of APP.

The noncoding miRNA-34a (miR-34a) is involved in Alzheimer's disease (AD) pathologenesis and shows potential for application as a biomarker for early diagnosis and intervention. Here, we established miR-34a knockout mice in an APP/PS1 background (APP/PS1-miR-34a KO mice) by crossbreeding miR-34a-/- mice with APP/PS1 mice. We then investigated cognitive impairment and related pathologies. The results showed that the level of miR-34a was increased at about 6months in APP/PS1 mice, consistent with the increase in amyloid ß (Aß), and cognitive function was significantly improved in mice when miR-34a was knocked out in 9-month-old and 12-month-old mice, indicating that miR-34a is a potential candidate for determining the progression of AD. Furthermore, we assessed the processing of amyloid precursor protein (APP) and the results suggest that cognitive improvement by miR-34a knock out was mainly triggered by depression of γ-secretase activity, without affecting ß- and α-secretase activities, indicating that miR-34a plays an important role in AD pathology, mainly by inhibiting the amyloidogenic processing of APP, without altering the non-amyloidogenic processing of APP.

Hierarchically biomimetic scaffold of a collagen-mesoporous bioactive glass nanofiber composite for bone tissue engineering.

Mesoporous bioactive glass nanofibers (MBGNFs) were prepared by a sol-gel/electrospinning technique. Subsequently, a collagen-MBGNF (CM) composite scaffold that simultaneously possessed a macroporous structure and collagen nanofibers was fabricated by a gelation and freeze-drying process. Additionally, immersing the CM scaffold in a simulated body fluid resulted in the formation of bone-like apatite minerals on the surface. The CM scaffold provided a suitable environment for attachment to the cytoskeleton. Based on the measured alkaline phosphatase activity and protein expression levels of osteocalcin and bone sialoprotein, the CM scaffold promoted the differentiation and mineralization of MG63 osteoblast-like cells. In addition, the bone regeneration ability of the CM scaffold was examined using a rat calvarial defect model in vivo. The results revealed that CM is biodegradable and could promote bone regeneration. Therefore, a CM composite scaffold is a potential bone graft for bone tissue engineering applications.

Hyperbaric oxygen suppresses hypoxic-ischemic brain damage in newborn rats.

The optimal therapeutic time-window and protective mechanism of hyperbaric oxygen in hypoxic-ischemic brain damage remain unclear. This study aimed to determine the neuroprotective effects of hyperbaric oxygen. Following hypoxic-ischemic brain damage modeling in neonatal rats, hyperbaric oxygen was administered at 6, 24, 48, and 72 hours and 1 week after hypoxia, respectively, once daily for 1 week. Fourteen days after hypoxic-ischemic brain damage, cell density and apoptosis rate, number of Fas-L+, caspase-8+, and caspase-3+ neuronal cells, levels of nitric oxide, malondialdehyde, and superoxide dismutase in hippocampus were examined. Morris water maze test was conducted 28 days after insult. Significant improvements were found in cell density, rate of apoptosis, oxidative stress markers, FasL, and caspases in rats treated with hyperbaric oxygen within 72 hours compared to hypoxic-ischemic injury. Similarly, time-dependent behavioral amelioration was observed in pups treated with hyperbaric oxygen. Our findings suggest that hyperbaric oxygen protects against hypoxic-ischemic brain damage by inhibiting oxidative stress and FasL-induced apoptosis, and optimal therapeutic time window is within 72 hours after hypoxic-ischemic brain damage.

ABCD² score may discriminate minor stroke from TIA on patient admission.

With the advent of time-dependent thrombolytic therapy for ischemic stroke, it has become increasingly important to differentiate transient ischemic attack (TIA) from minor stroke patients after symptom onset quickly. This study investigated the difference between TIA and minor stroke based on age, blood pressure, clinical features, duration of TIA, presence of diabetes, ABCD² score, digital subtraction angiography (DSA) and blood lipids. One hundred seventy-one patients with clinical manifestations as transient neurological deficits in Nanjing Drum Tower Hospital were studied retrospectively. All patients were evaluated by ABCD² score, blood lipid test, fibrinogen, and Holter electrocardiograph and DSA on admission. Patients were categorized into TIA group or minor stroke group according to CT and MRI scan 24 h within symptom onset. The study suggested that minor stroke patients were more likely to have a higher ABCD² score (odds ratio (OR) 2.060; 95% confidence interval (CI) 1.293-3.264). Receiver-operating characteristic curves identified ABCD² score >4 as the optimal cut-off for minor stroke diagnosis. Total serum cholesterol seemed a better diagnostic indicator to discriminate minor stroke from TIA (OR 4.815; 95% CI 0.946-1.654) than other blood lipids in simple logistic regression, but not valuable for the differentiation between TIA and minor stroke in multivariate logistic regression. Higher severity of intracranial internal carotid stenosis, especially >90%, were more likely to have minor stroke, but was not a reliable diagnostic indicator (P > 0.05). ABCD² could help clinicians to differentiate possible TIA from minor stroke at hospital admission while blood lipid parameters and artery stenosis location offer limited help.

Hydroxysafflor yellow A suppresses inflammatory responses of BV2 microglia after oxygen-glucose deprivation.

Inflammation is a pivotal pathological progress in the development of ischemic stroke. Modulating inflammatory cytokines released by microglia is thought to be a potential strategy for the treatment of ischemic stroke. Hydroxy-safflor yellow A (HSYA), a chemical component of the safflower yellow pigments, was reported to protect against brain injury in experimental stroke through anti-inflammation. However, the direct effect of HSYA on microglia following ischemia is unknown. This study confirmed whether HSYA could suppress inflammatory responses of BV2 microglia after oxygen glucose deprivation (OGD). BV2 microglia viability after OGD with or without HSYA was measured by MTT assay, PI/Annexin staining and LDH assay. Pro-inflammatory cytokines including 1L-1ß, TNF-α, iNOS, COX-2, MCP-1 were determined by RT-PCR and western blotting. Activity of NF-κB and MAPK pathway were detected by western blotting. The results demonstrated that HSYA improved the viability of BV2 cells 12h after OGD with the profound dosage at 100mg/L by MTT assay. This observation was also confirmed by PI/Annexin staining and LDH assay. HSYA decreased the mRNA level of 1L-1ß, TNF-α, iNOS, COX-2, MCP-1 and protein level of iNOS, COX-2 in BV2 microglia 12h after OGD. OGD enhanced the phosphorylation of p38 and nuclear translocation of p65 in BV2 microglia, which was partially reserved by HSYA. Our results suggested that HSYA suppressed inflammatory responses in BV2 microglia induced by OGD, which is probably associated with the inhibition of the NF-κB signaling pathway and phosphorylation of p38.