Protective effect of increased O-GlcNAc cycling against 6-OHDA induced Parkinson's disease pathology.

This study aimed to elucidate the role of O-GlcNAc cycling in 6-hydroxydopamine (6-OHDA)-induced Parkinson's disease (PD)-like neurodegeneration and the underlying mechanisms. We observed dose-dependent downregulation of O-GlcNAcylation, accompanied by an increase in O-GlcNAcase following 6-OHDA treatment in both mouse brain and Neuro2a cells. Interestingly, elevating O-GlcNAcylation through glucosamine (GlcN) injection provided protection against PD pathogenesis induced by 6-OHDA. At the behavioral level, GlcN mitigated motor deficits induced by 6-OHDA, as determined using the pole, cylinder, and apomorphine rotation tests. Furthermore, GlcN attenuated 6-OHDA-induced neuroinflammation and mitochondrial dysfunction. Notably, augmented O-GlcNAcylation, achieved through O-GlcNAc transferase (OGT) overexpression in mouse brain, conferred protection against 6-OHDA-induced PD pathology, encompassing neuronal cell death, motor deficits, neuroinflammation, and mitochondrial dysfunction. These collective findings suggest that O-GlcNAcylation plays a crucial role in the normal functioning of dopamine neurons. Moreover, enhancing O-GlcNAcylation through genetic and pharmacological means could effectively ameliorate neurodegeneration and motor impairment in an animal model of PD. These results propose a potential strategy for safeguarding against the deterioration of dopamine neurons implicated in PD pathogenesis.

Steady State and Time-Dependent Fluorescent Peptide Assays for Protein Kinases.

Protein kinases catalyze the phosphorylation of proteins most commonly on Ser, Thr, and Tyr residues and regulate many cellular events in eukaryotic cells, such as cell cycle progression, transcription, metabolism, and apoptosis. Protein kinases each have a conserved ATP-binding site and one or more substrate-binding site(s) that exhibit recognition features for different protein substrates. By bringing ATP and a substrate into proximity, each protein kinase can transfer the γ phosphate of the ATP molecule to a hydroxyl group of the target residue on the substrate. In such a way, signaling pathways downstream from the substrate can be regulated based on the phosphorylated versus dephosphorylated status of the substrate. Although there are a number of ways to assay the activity of protein kinases, most of them are technically cumbersome and/or are indirect or based on quenched reactions. This protocol describes an assay employing a fluorescent peptide substrate to detect phosphorylation by protein kinases in real time. The assay is based on the principle that the phosphorylation of the peptide substrate leads to an increase in the fluorescence emission intensity of an appended fluorophore. We extend the application of this assay to an example of how to assess time-dependent covalent inhibition of kinases as well. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Measuring protein kinase activity using fluorescent peptides Alternate Protocol: Measuring protein kinase activity using a fluorescence plate reader Support Protocol: Labeling peptides with sox fluorophore Basic Protocol 2: Measuring time-dependent ATP-competitive inhibition of protein kinases using fluorescent peptides.

Unexpected inhibition of the lipid kinase PIKfyve reveals an epistatic role for p38 MAPKs in endolysosomal fission and volume control.

p38 mitogen-activated protein kinases (MAPKs) participate in autophagic signaling; and previous reports suggest that pyridinyl imidazole p38 MAPK inhibitors, including SB203580 and SB202190, induce cell death in some cancer cell-types through unrestrained autophagy. Subsequent studies, however, have suggested that the associated cytoplasmic vacuolation resulted from off-target inhibition of an unidentified enzyme. Herein, we report that SB203580-induced vacuolation is rapid, reversible, and relies on the class III phosphatidylinositol 3-kinase (PIK3C3) complex and the production of phosphatidylinositol 3-phosphate [PI(3)P] but not on autophagy per se. Rather, vacuolation resulted from the accumulation of Rab7 on late endosome and lysosome (LEL) membranes, combined with an osmotic imbalance that triggered severe swelling in these organelles. Inhibition of PIKfyve, the lipid kinase that converts PI(3)P to PI(3,5)P2 on LEL membranes, produced a similar phenotype in cells; therefore, we performed in vitro kinase assays and discovered that both SB203580 and SB202190 directly inhibited recombinant PIKfyve. Cancer cells treated with either drug likewise displayed significant reductions in the endogenous levels of PI(3,5)P2. Despite these results, SB203580-induced vacuolation was not entirely due to off-target inhibition of PIKfyve, as a drug-resistant p38α mutant suppressed vacuolation; and combined genetic deletion of both p38α and p38ß dramatically sensitized cells to established PIKfyve inhibitors, including YM201636 and apilimod. The rate of vacuole dissolution (i.e., LEL fission), following the removal of apilimod, was also significantly reduced in cells treated with BIRB-796, a structurally unrelated p38 MAPK inhibitor. Thus, our studies indicate that pyridinyl imidazole p38 MAPK inhibitors induce cytoplasmic vacuolation through the combined inhibition of both PIKfyve and p38 MAPKs, and more generally, that p38 MAPKs act epistatically to PIKfyve, most likely to promote LEL fission.

PLCγ1 in dopamine neurons critically regulates striatal dopamine release via VMAT2 and synapsin III.

Dopamine neurons are essential for voluntary movement, reward learning, and motivation, and their dysfunction is closely linked to various psychological and neurodegenerative diseases. Hence, understanding the detailed signaling mechanisms that functionally modulate dopamine neurons is crucial for the development of better therapeutic strategies against dopamine-related disorders. Phospholipase Cγ1 (PLCγ1) is a key enzyme in intracellular signaling that regulates diverse neuronal functions in the brain. It was proposed that PLCγ1 is implicated in the development of dopaminergic neurons, while the physiological function of PLCγ1 remains to be determined. In this study, we investigated the physiological role of PLCγ1, one of the key effector enzymes in intracellular signaling, in regulating dopaminergic function in vivo. We found that cell type-specific deletion of PLCγ1 does not adversely affect the development and cellular morphology of midbrain dopamine neurons but does facilitate dopamine release from dopaminergic axon terminals in the striatum. The enhancement of dopamine release was accompanied by increased colocalization of vesicular monoamine transporter 2 (VMAT2) at dopaminergic axon terminals. Notably, dopamine neuron-specific knockout of PLCγ1 also led to heightened expression and colocalization of synapsin III, which controls the trafficking of synaptic vesicles. Furthermore, the knockdown of VMAT2 and synapsin III in dopamine neurons resulted in a significant attenuation of dopamine release, while this attenuation was less severe in PLCγ1 cKO mice. Our findings suggest that PLCγ1 in dopamine neurons could critically modulate dopamine release at axon terminals by directly or indirectly interacting with synaptic machinery, including VMAT2 and synapsin III.

Unleashing the Potential of 1,3-Diketone Analogues as Selective LH2 Inhibitors.

Lysyl hydroxylase 2 (LH2) catalyzes the formation of highly stable hydroxylysine aldehyde-derived collagen cross-links (HLCCs), thus promoting lung cancer metastasis through its capacity to modulate specific types of collagen cross-links within the tumor stroma. Using 1 and 2 from our previous high-throughput screening (HTS) as lead probes, we prepared a series of 1,3-diketone analogues, 1-18, and identified 12 and 13 that inhibit LH2 with IC50's of approximately 300 and 500 nM, respectively. Compounds 12 and 13 demonstrate selectivity for LH2 over LH1 and LH3. Quantum mechanics/molecular mechanics (QM/MM) modeling indicates that the selectivity of 12 and 13 may stem from noncovalent interactions like hydrogen bonding between the morpholine/piperazine rings with the LH2-specific Arg661. Treatment of 344SQ WT cells with 13 resulted in a dose-dependent reduction in their migration potential, whereas the compound did not impede the migration of the same cell line with an LH2 knockout (LH2KO).

GABAergic-like dopamine synapses in the brain.

Dopamine synapses play a crucial role in volitional movement and reward-related behaviors, while dysfunction of dopamine synapses causes various psychiatric and neurological disorders. Despite this significance, the true biological nature of dopamine synapses remains poorly understood. Here, we show that dopamine transmission is strongly correlated with GABA co-transmission across the brain and dopamine synapses are structured and function like GABAergic synapses with marked regional heterogeneity. In addition, GABAergic-like dopamine synapses are clustered on the dendrites, and GABA transmission at dopamine synapses has distinct physiological properties. Interestingly, the knockdown of neuroligin-2, a key postsynaptic protein at GABAergic synapses, unexpectedly does not weaken GABA co-transmission but instead facilitates it at dopamine synapses in the striatal neurons. More importantly, the attenuation of GABA co-transmission precedes deficits in dopaminergic transmission in animal models of Parkinson's disease. Our findings reveal the spatial and functional nature of GABAergic-like dopamine synapses in health and disease.

Melatonin and Exercise Counteract Sarcopenic Obesity through Preservation of Satellite Cell Function.

Sarcopenic obesity (SO) is characterized by atrophic skeletal muscle impairment (sarcopenia) and obesity, which is associated with adverse outcomes of morbidity and mortality in elderly people. We investigated the effects of melatonin and exercise training on SO in 32-week-old senescence-accelerated mouse-prone-8 (SAMP8) mice fed a normal diet or a high-fat diet for 16 weeks. Melatonin, exercise, or melatonin and exercise for 8 weeks displayed reductions in the SO-induced impairment of skeletal muscle function and atrophy. Specifically, a decrease in mitochondrial calcium retention capacity in skeletal muscles observed in the HFD-con group was attenuated in melatonin and/or exercise intervention groups. More importantly, HFD-con mice displayed a lower number of Pax7+ satellite cells (SCs) and higher expression of p16ink than P8ND mice, which were attenuated by melatonin and/or exercise interventions. The cellular senescence in SC-derived primary myoblasts from HFD-con mice was significantly attenuated in myoblasts from the melatonin and/or exercise groups, which was reproduced in a senescence model of H2O2-treated C2C12 myoblasts. Our results suggest that melatonin and exercise training attenuate SO-induced skeletal muscle dysfunction, at least in part, through preserving the SC pool by inhibiting cellular senescence and attenuating mitochondrial dysfunction.

Unexpected inhibition of the lipid kinase PIKfyve reveals an epistatic role for p38 MAPKs in endolysosomal fission and volume control.

p38 mitogen-activated protein kinases (MAPKs) regulate early endocytic trafficking, but their effects on late endocytic trafficking remain unclear. Herein, we report that the pyridinyl imidazole p38 MAPK inhibitors, SB203580 and SB202190, induce a rapid but reversible Rab7-dependent accumulation of large cytoplasmic vacuoles. While SB203580 did not induce canonical autophagy, phosphatidylinositol 3-phosphate [PI(3)P] accumulated on vacuole membranes, and inhibition of the class III PI3-kinase (PIK3C3/VPS34) suppressed vacuolation. Ultimately, vacuolation resulted from the fusion of ER/Golgi-derived membrane vesicles with late endosomes and lysosomes (LELs), combined with an osmotic imbalance in LELs that led to severe swelling and a decrease in LEL fission. Since PIKfyve inhibitors induce a similar phenotype by preventing the conversion of PI(3)P to PI(3,5)P2, we performed in vitro kinase assays and found that PIKfyve activity was unexpectedly inhibited by SB203580 and SB202190, corresponding to losses in endogenous PI(3,5)P2 levels in treated cells. However, vacuolation was not entirely due to 'off-target' inhibition of PIKfyve by SB203580, as a drug-resistant p38α mutant suppressed vacuolation. Moreover, genetic deletion of both p38α and p38ß rendered cells dramatically more sensitive to PIKfyve inhibitors, including YM201636 and apilimod. In subsequent 'washout' experiments, the rate of vacuole dissolution upon the removal of apilimod was also significantly reduced in cells treated with BIRB-796, a structurally unrelated p38 MAPK inhibitor. Thus, p38 MAPKs act epistatically to PIKfyve to promote LEL fission; and pyridinyl imidazole p38 MAPK inhibitors induce cytoplasmic vacuolation through the combined inhibition of both PIKfyve and p38 MAPKs.

Early Invasive Strategy Based on the Time of Symptom Onset of Non-ST-Segment Elevation Myocardial Infarction.

BACKGROUND: A limitation of the current guidelines regarding the timing of invasive coronary angiography for patients with non-ST-segment elevation acute coronary syndrome is the randomization time. To date, no study has reported the clinical outcomes of invasive strategy timing on the basis of the time of symptom onset. OBJECTIVES: The aim of this study was to investigate the effect of invasive strategy timing from the time of symptom onset on the 3-year clinical outcomes of patients with non-ST-segment elevation myocardial infarction (NSTEMI). METHODS: Among 13,104 patients from the Korea Acute Myocardial Infarction Registry-National Institutes of Health, 5,856 patients with NSTE myocardial infarction were evaluated. The patients were categorized according to symptom-to-catheter (StC) time (<48 or ≥48 hours). The primary outcome was 3-year all-cause mortality. RESULTS: Overall, 3,919 patients (66.9%) were classified into the StC time <48 hours group. This group had lower all-cause mortality than the group with StC time ≥48 hours (7.3% vs 13.4%; P < 0.001). The lower risk for all-cause mortality in the group with StC time <48 hours group was consistent in all subgroups. Notably, emergency medical service use (HR: 0.31; 95% CI: 0.19-0.52) showed a lower risk for all-cause mortality than no emergency medical service use (HR: 0.54; 95% CI: 0.46-0.65; P value for interaction = 0.008). CONCLUSIONS: An early invasive strategy on the basis of StC time was associated with a decreased risk for all-cause mortality in patients with NSTEMI. Because the study was based on a prospective registry, the results should be considered hypothesis generating, highlighting the need for further research. (iCReaT Study No. C110016).

Post-PCI Risk Assessment by Inflammation Activity According to Disease Acuity and Time from Procedure.

BACKGROUND: High-sensitivity C-reactive protein (hs-CRP) has been proposed as an indicator of inflammation and cardiovascular risk. However, little is known of the comparative temporal profile of hs-CRP and its relation to outcomes according to the disease acuity. METHODS: We enrolled 4,263 East Asian patients who underwent percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI) and stable disease. hs-CRP was measured at baseline and 1 month post-PCI. Major adverse cardiovascular events (MACE: the composite occurrence of death, myocardial infarction, or stroke) and major bleeding were followed up to 4 years. RESULT: The AMI group (n = 2,376; 55.7%) had higher hs-CRPbaseline than the non-AMI group (n = 1,887; 44.3%) (median: 1.5 vs. 1.0 mg/L; p < 0.001), which remained higher at 1 month post-PCI (median: 1.0 vs. 0.9 mg/L; p = 0.001). During 1 month, a high inflammatory-risk phenotype (upper tertile: hs-CRPbaseline ≥ 2.4 mg/L) was associated with a greater MACE in the AMI group (adjusted hazard ratio [HRadj]: 7.66; 95% confidence interval [CI]: 2.29-25.59; p < 0.001), but not in the non-AMI group (HRadj: 0.74; 95% CI: 0.12-4.40; p = 0.736). Between 1 month and 4 years, a high inflammatory-risk phenotype (upper tertile: hs-CRP1 month ≥ 1.6 mg/L) was associated with greater MACE compared to the other phenotype in both the AMI (HRadj: 2.40; 95% CI: 1.73-3.45; p < 0.001) and non-AMI groups (HRadj: 2.67; 95% CI: 1.80-3.94; p < 0.001). CONCLUSION: AMI patients have greater inflammation during the early and late phases than non-AMI patients. Risk phenotype of hs-CRPbaseline correlates with 1-month outcomes only in AMI patients. However, the prognostic implications of this risk phenotype appears similar during the late phase, irrespective of the disease acuity.

Reshaping tumor immune microenvironment by Epstein-Barr virus activation in the stroma of colorectal cancer.

The formation of tumor immune microenvironment (TIM) is complicated and poorly understood. Little is known about the effect of a viral infection potentially inducing an additional immune response in the TIM. Here, we identify Epstein-Barr virus (EBV) expression in the TIM in colorectal cancer (CRC) tissue through EBV-encoded RNA in-situ hybridization and RNA sequencing data and investigate the effects of EBV on TIM composition and clinical outcomes. EBV was detected in tumor-infiltrating lymphocytes, but not in cancer cells. EBV positivity was associated with older age, male sex, and SMAD4 mutations. EBV-positive tumors were characterized by enrichment in chemokine/cytokine signaling pathways and altered immune cell composition, including plasma and CD4 T cells, as well as cancer cells intrinsically enriched pathways related to immune tolerance, leading to poor prognosis. In conclusion, we identified EBV expression in TIM and suggested its association with poor prognosis by altering the TIM in CRC.

A Multi-Center, Prospective Observational Study to Investigate the Safety, Compliance, and Efficacy of Omethyl QTlet Soft Capsule.

Omega-3 fatty acids have been shown to be effective in lowering triglyceride (TG) levels; however, tolerability issues arise due to the large size of the pills. The purpose of this study was to examine the safety, compliance, and efficacy of Omethyl QTlet soft capsules (OQCs). This multi-center, prospective, observational study evaluated the safety, compliance, and efficacy of OQCs. Patients with hypertriglyceridemia with a history of omega-3 fatty acid intake were enrolled in this study and were prescribed OQCs (2 g−4 g/day) for eight weeks. All adverse events (AEs), adverse drug reactions (ADRs), and serious adverse events (SAEs) were recorded for safety evaluation. Adherence to treatment was assessed using questionnaires, and efficacy was assessed by changes in lipid and lipoprotein levels after eight weeks from baseline. The convenience of taking medication was analyzed for 580 patients, and the efficacy test was performed for 563 patients. The AE and ADR rates were 8.2% and 5.7%, respectively. There were only two SAEs. Of the patients, 55.8% responded that the OQC improved medication convenience, and mean changes in TG, total cholesterol, LDL-C, and non-HDL-C from baseline to eight weeks were −37.88 mg/dL, −11.56 mg/dL, −5.55 mg/dL, and −10.87 mg/dL, respectively (p-values < 0.001). In patients who had previously taken omega-3 fatty acids, OQCs showed safety and efficacy in lowering TG, and it was confirmed that compliance with medicine also improved compared to omega-3 fatty acids.

A Multicenter, Randomized, Double-blind, Active-controlled, Factorial Design, Phase III Clinical Trial to Evaluate the Efficacy and Safety of Combination Therapy of Pitavastatin and Ezetimibe Versus Monotherapy of Pitavastatin in Patients With Primary Hypercholesterolemia.

PURPOSE: Pitavastatin is a unique lipophilic statin with moderate efficacy in lowering LDL-C levels by 30% to 50% with a tolerable safety profile. However, the efficacy of adding ezetimibe to pitavastatin in patients with dyslipidemia has not been well investigated. Therefore, the objective of this double-blind, multicenter, randomized, Phase III study was to compare the efficacy and safety of pitavastatin and ezetimibe combination therapy with those of pitavastatin monotherapy in Korean patients with primary hypercholesterolemia. METHODS: Korean men and women aged >19 and <80 years with primary hypercholesterolemia requiring medical treatment were included in this study. During the 8-week screening period, all patients were instructed to make therapeutic lifestyle changes. The screening period consisted of a 4-week washout period and a placebo run-in period (4-8 weeks). During treatment period I, patients were randomly assigned to receive 1 of 4 treatments: pitavastatin 2 mg plus ezetimibe 10 mg, pitavastatin 2 mg, pitavastatin 4 mg plus ezetimibe 10 mg, or pitavastatin 4 mg. The 8-week double-blind treatment period then commenced. Adverse events (AEs), clinical laboratory data, and vital signs were assessed in all patients. FINDINGS: The percentages in LDL-C from baseline after 8 weeks of double-blind treatment decreased significantly in the pooled pitavastatin/ezetimibe (-52.8% [11.2%]) and pooled pitavastatin (-37.1% [14.1%]) groups. Treatment with pitavastatin/ezetimibe resulted in a significantly greater LDL-C-lowering effect than that with pitavastatin (difference, -15.8 mg/dL; 95% CI, -18.7 to -12.9; P < 0.001). The precentages of achieving LDL-C goal in pooled pitavastatin/ezetimibe and pooled pitavastatin groups were 94.2% and 69.1%, respectively (P < 0.001). There were no significant differences in the incidence of overall AEs and adverse drug reactions. Serious AEs were comparable between the groups. IMPLICATIONS: Pitavastatin and ezetimibe combinations effectively and safely decreased LDL-C levels by >50% in patients with dyslipidemia. The safety and tolerability of pitavastatin and ezetimibe combination therapy were comparable with those of pitavastatin monotherapy. CLINICALTRIALS: gov identifier: NCT04584736.

High-Throughput Assay for Identifying Diverse Antagonists of the Binding Interaction between the ACE2 Receptor and the Dynamic Spike Proteins of SARS-CoV-2.

SARS-CoV-2, a coronavirus strain that started a worldwide pandemic in early 2020, attaches to human cells by binding its spike (S) glycoprotein to a host receptor protein angiotensin-converting enzyme 2 (ACE2). Blocking the interaction between the S protein and ACE2 has emerged as an important strategy for preventing viral infection. We systematically developed and optimized an AlphaLISA assay to investigate binding events between ACE2 and the ectodomain of the SARS-CoV-2 S protein (S-614G: residues 1-1208 with a D614G mutation). Using S-614G permits discovering potential allosteric inhibitors that stabilize the S protein in a conformation that impedes its access to ACE2. Over 30,000 small molecules were screened in a high-throughput format for activity against S-614G and ACE2 binding using the AlphaLISA assay. A viral entry assay was used to validate hits using lentiviral particles pseudotyped with the full-length S protein of the Wuhan-1 strain. Two compounds identified in the screen, oleic acid and suramin, blocked the attachment of S-614G to ACE2 and S protein-driven cell entry into Calu-3 and ACE2-overexpressing HEK293T cells. Oleic acid inhibits S-614G binding to ACE2 far more potently than to the receptor-binding domain (RBD, residues 319-541 of SARS-CoV-2 S), potentially indicating a noncompetitive mechanism. The results indicate that using the full-length ectodomain of the S protein can be important for identifying allosteric inhibitors of ACE2 binding. The approach reported here represents a rapidly adaptable format for discovering receptor-binding inhibitors to S-proteins of future coronavirus strains.

GRK3 is a poor prognosticator and serves as a therapeutic target in advanced gastric adenocarcinoma.

BACKGROUND: G protein-coupled receptor (GPCR) is the most targeted protein family by the FDA-approved drugs. GPCR-kinase 3 (GRK3) is critical for GPCR signaling. Our genomic analysis showed that GRK3 expression correlated with poor prognosis of gastric adenocarcinoma (GAC) patients. However, GRK3's functions and clinical utility in GAC progression and metastases are unknown. METHODS: We studied GRK3 expression in normal, primary, and metastatic GAC tissues. We identified a novel GRK3 inhibitor, LD2, through a chemical-library screen. Through genetic and pharmacologic modulations of GRK3, a series of functional and molecular studies were performed in vitro and in vivo. Impact of GRK3 on YAP1 and its targets was determined. RESULTS: GRK3 was overexpressed in GAC tissues compared to normal and was even higher in peritoneal metastases. Overexpression (OE) of GRK3 was significantly associated with shorter survival. Upregulation of GRK3 in GAC cells increased cell invasion, colony formation, and proportion of ALDH1+ cells, while its downregulation reduced these attributes. Further, LD2 potently and specifically inhibited GRK3, but not GRK2, a very similar kinase to GRK3. LD2 highly suppressed GAC cells' malignant phenotypes in vitro. Mechanistically, GRK3 upregulated YAP1 in GAC tissues and its transcriptional downstream targets: SOX9, Birc5, Cyr61 and CTGF. Knockdown (KD) YAP1 rescued the phenotypes of GRK3 OE in GAC cells. GRK3 OE significantly increased tumor growth but LD2 inhibited tumor growth in the PDX model and dramatically suppressed peritoneal metastases induced by GRK3 OE. CONCLUSIONS: GRK3, a poor prognosticator for survival, conferred aggressive phenotype. Genetic silencing of GRK3 or its inhibitor LD2 blunted GRK3-conferred malignant attributes, suggesting GRK3 as a novel therapeutic target in advanced GAC.