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Research Square Jun 2024Inhibition of translation initiation using eIF4A inhibitors like (-)-didesmethylrocaglamide [(-)-DDR] and (-)-rocaglamide [(-)-Roc] is a potential cancer treatment...
Inhibition of translation initiation using eIF4A inhibitors like (-)-didesmethylrocaglamide [(-)-DDR] and (-)-rocaglamide [(-)-Roc] is a potential cancer treatment strategy as they simultaneously diminish multiple oncogenic drivers. We showed that human and dog osteosarcoma cells expressed high levels of eIF4A1/2, particularly eIF4A2. Genetic depletion of eIF4A1 and/or 2 slowed osteosarcoma cell growth. To advance preclinical development of eIF4A inhibitors, we demonstrated the importance of (-)-chirality in DDR for growth-inhibitory activity. Bromination of DDR at carbon-5 abolished growth-inhibitory activity, while acetylating DDR at carbon-1 was tolerated. Like DDR and Roc, DDR-acetate increased the γH2A.X levels and induced G /M arrest and apoptosis. Consistent with translation inhibition, these rocaglates decreased the levels of several mitogenic kinases, the STAT3 transcription factor, and the stress-activated protein kinase p38. However, phosphorylated p38 was greatly enhanced in treated cells, suggesting activation of stress response pathways. RNA sequencing identified as a top upregulated gene in both DDR- and Roc-treated osteosarcoma cells, but the Rho inhibitor Rhosin did not enhance the growth-inhibitory activity of (-)-DDR or (-)-Roc. Nonetheless, these rocaglates potently suppressed tumor growth in a canine osteosarcoma patient-derived xenograft model. These results suggest that these eIF4A inhibitors can be leveraged to treat both human and dog osteosarcomas.
PubMed: 38947012
DOI: 10.21203/rs.3.rs-4494024/v1 -
MedRxiv : the Preprint Server For... Jun 2024Plasma p-tau217 and Tau-PET are strong prognostic biomarkers in Alzheimer's disease (AD), but their relative performance in predicting future cognitive decline among...
Plasma p-tau217 and Tau-PET are strong prognostic biomarkers in Alzheimer's disease (AD), but their relative performance in predicting future cognitive decline among cognitively unimpaired (CU) individuals is unclear. In this head-to-head comparison study including 9 cohorts and 1534 individuals, we found that plasma p-tau217 and medial temporal lobe Tau-PET signal showed similar associations with cognitive decline on a global cognitive composite test (R =0.32 vs R =0.32, p =0.812) and with progression to mild cognitive impairment (Hazard ratio[HR] =1.56[1.43-1.70] vs HR =1.63[1.50-1.77], p =0.627). Combined plasma and PET models were superior to the single biomarker models (R =0.36, p<0.01). Furthermore, sequential selection using plasma p-tau217 and then Tau-PET reduced the number of participants required for a clinical trial by 94%, compared to a 75% reduction when using plasma p-tau217 alone. We conclude that plasma p-tau217 and Tau-PET showed similar performance for predicting future cognitive decline in CU individuals, and their sequential use (i.e., plasma p-tau217 followed by Tau-PET in a subset with high plasma p-tau217) is useful for screening in clinical trials in preclinical AD.
PubMed: 38947004
DOI: 10.1101/2024.06.12.24308824 -
Research Square Jun 2024Tauopathies, including Alzheimer's disease (AD) and Frontotemporal Dementia (FTD), are histopathologically defined by the aggregation of hyperphosphorylated pathological...
Virus-like particle (VLP)-based vaccine targeting tau phosphorylated at Ser396/Ser404 (PHF1) site outperforms phosphorylated S199/S202 (AT8) site in reducing tau pathology and restoring cognitive deficits in the rTg4510 mouse model of tauopathy.
Tauopathies, including Alzheimer's disease (AD) and Frontotemporal Dementia (FTD), are histopathologically defined by the aggregation of hyperphosphorylated pathological tau (pTau) as neurofibrillary tangles in the brain. Site-specific phosphorylation of tau occurs early in the disease process and correlates with progressive cognitive decline, thus serving as targetable pathological epitopes for immunotherapeutic development. Previously, we developed a vaccine (Qβ-pT181) displaying phosphorylated Thr181 tau peptides on the surface of a Qβ bacteriophage virus-like particle (VLP) that induced robust antibody responses, cleared pathological tau, and rescued memory deficits in a transgenic mouse model of tauopathy. Here we report the characterization and comparison of two additional Qβ VLP-based vaccines targeting the dual phosphorylation sites Ser199/Ser202 (Qβ-AT8) and Ser396/Ser404 (Qβ-PHF1). Both Qβ-AT8 and Qβ-PHF1 vaccines elicited high-titer antibody responses against their pTau epitopes. However, only Qβ-PHF1 rescued cognitive deficits, reduced soluble and insoluble pathological tau, and reactive microgliosis in a 4-month rTg4510 model of FTD. Both sera from Qβ-AT8 and Qβ-PHF1 vaccinated mice were specifically reactive to tau pathology in human AD post-mortem brain sections. These studies further support the use of VLP-based immunotherapies to target pTau in AD and related tauopathies and provide potential insight into the clinical efficacy of various pTau epitopes in the development of immunotherapeutics.
PubMed: 38946961
DOI: 10.21203/rs.3.rs-4390998/v1 -
International Journal of Nanomedicine 2024It is well-established that osteoclast activity is significantly influenced by fluctuations in intracellular pH. Consequently, a pH-sensitive gated nano-drug delivery...
BACKGROUND
It is well-established that osteoclast activity is significantly influenced by fluctuations in intracellular pH. Consequently, a pH-sensitive gated nano-drug delivery system represents a promising therapeutic approach to mitigate osteoclast overactivity. Our prior research indicated that naringin, a natural flavonoid, effectively mitigates osteoclast activity. However, naringin showed low oral availability and short half-life, which hinders its clinical application. We developed a drug delivery system wherein chitosan, as gatekeepers, coats mesoporous silica nanoparticles loaded with naringin (CS@MSNs-Naringin). However, the inhibitory effects of CS@MSNs-Naringin on osteoclasts and the underlying mechanisms remain unclear, warranting further research.
METHODS
First, we synthesized CS@MSNs-Naringin and conducted a comprehensive characterization. We also measured drug release rates in a pH gradient solution and verified its biosafety. Subsequently, we investigated the impact of CS@MSNs-Naringin on osteoclasts induced by bone marrow-derived macrophages, focusing on differentiation and bone resorption activity while exploring potential mechanisms. Finally, we established a rat model of bilateral critical-sized calvarial bone defects, in which CS@MSNs-Naringin was dispersed in GelMA hydrogel to achieve in situ drug delivery. We observed the ability of CS@MSNs-Naringin to promote bone regeneration and inhibit osteoclast activity in vivo.
RESULTS
CS@MSNs-Naringin exhibited high uniformity and dispersity, low cytotoxicity (concentration≤120 μg/mL), and significant pH sensitivity. In vitro, compared to Naringin and MSNs-Naringin, CS@MSNs-Naringin more effectively inhibited the formation and bone resorption activity of osteoclasts. This effect was accompanied by decreased phosphorylation of key factors in the NF-κB and MAPK signaling pathways, increased apoptosis levels, and a subsequent reduction in the production of osteoclast-specific genes and proteins. In vivo, CS@MSNs-Naringin outperformed Naringin and MSNs-Naringin, promoting new bone formation while inhibiting osteoclast activity to a greater extent.
CONCLUSION
Our research suggested that CS@MSNs-Naringin exhibited the strikingly ability to anti-osteoclasts in vitro and in vivo, moreover promoted bone regeneration in the calvarial bone defect.
Topics: Flavanones; Animals; Osteoclasts; Bone Regeneration; Silicon Dioxide; Hydrogen-Ion Concentration; Nanoparticles; Rats; Mice; Rats, Sprague-Dawley; Chitosan; Male; Drug Liberation; Porosity; Drug Carriers; Bone Resorption; RAW 264.7 Cells; Drug Delivery Systems; Cell Differentiation
PubMed: 38946884
DOI: 10.2147/IJN.S456545 -
Analytical Cellular Pathology... 2024Biliary atresia (BA) is a devastating congenital disease characterized by inflammation and progressive liver fibrosis. Activation of hepatic stellate cells (HSCs) plays...
BACKGROUND
Biliary atresia (BA) is a devastating congenital disease characterized by inflammation and progressive liver fibrosis. Activation of hepatic stellate cells (HSCs) plays a central role in the pathogenesis of hepatic fibrosis. Our study aimed to investigate the pharmacological effect and potential mechanism of pirfenidone (PFD) and andrographolide (AGP) separately and together on liver fibrosis of BA.
MATERIALS AND METHODS
The bile ducts of male C57BL/6J mice were ligated or had the sham operation. The effects of PFD and/or AGP on liver fibrosis of BA were evaluated. Human hepatic stellate cells (LX-2) were also treated with PFD and/or AGP .
RESULTS
PFD and/or AGP ameliorates liver fibrosis and inflammation in the mice model of BA, as evidenced by significant downregulated in the accumulation of collagen fibers, hepatic fibrosis markers (-SMA, collagen I, and collagen IV), and inflammatory markers (IL-1, IL-6, and TNF-). Moreover, compared with monotherapy, these changes are more obvious in the combined treatment of PFD and AGP. Consistent with animal experiments, hepatic fibrosis markers (-SMA, collagen I, and CTGF) and inflammatory markers (IL-1, IL-6, and TNF-) were significantly decreased in activated LX-2 cells after PFD and/or AGP treatment. In addition, PFD and/or AGP inhibited the activation of HSCs by blocking the TGF-/Smad signaling pathway, and the combined treatment of PFD and AGP synergistically inhibited the phosphorylation of Smad2 and Smad3.
CONCLUSION
The combined application of PFD and AGP exerted superior inhibitive effects on HSC activation and liver fibrosis by mediating the TGF-/Smad signaling pathway as compared to monotherapy. Therefore, the combination of PFD and AGP may be a promising treatment strategy for liver fibrosis in BA.
Topics: Hepatic Stellate Cells; Animals; Liver Cirrhosis; Signal Transduction; Diterpenes; Male; Transforming Growth Factor beta; Mice, Inbred C57BL; Smad Proteins; Humans; Pyridones; Cell Line; Mice; Biliary Atresia; Disease Models, Animal; Drug Therapy, Combination
PubMed: 38946862
DOI: 10.1155/2024/2751280 -
CNS Neuroscience & Therapeutics Jul 2024Glycogen synthase kinase-3 (GSK3), consisting of GSK3α and GSK3β subtypes, is a complex protein kinase that regulates numerous substrates. Research has observed... (Review)
Review
Glycogen synthase kinase-3 (GSK3), consisting of GSK3α and GSK3β subtypes, is a complex protein kinase that regulates numerous substrates. Research has observed increased GSK3 expression in the brains of Alzheimer's disease (AD) patients and models. AD is a neurodegenerative disorder with diverse pathogenesis and notable cognitive impairments, characterized by Aβ aggregation and excessive tau phosphorylation. This article provides an overview of GSK3's structure and regulation, extensively analyzing its relationship with AD factors. GSK3 overactivation disrupts neural growth, development, and function. It directly promotes tau phosphorylation, regulates amyloid precursor protein (APP) cleavage, leading to Aβ formation, and directly or indirectly triggers neuroinflammation and oxidative damage. We also summarize preclinical research highlighting the inhibition of GSK3 activity as a primary therapeutic approach for AD. Finally, pending issues like the lack of highly specific and affinity-driven GSK3 inhibitors, are raised and expected to be addressed in future research. In conclusion, GSK3 represents a target in AD treatment, filled with hope, challenges, opportunities, and obstacles.
Topics: Humans; Alzheimer Disease; Animals; Glycogen Synthase Kinase 3; tau Proteins; Amyloid beta-Protein Precursor
PubMed: 38946682
DOI: 10.1111/cns.14818 -
Critical Reviews in Biochemistry and... Jul 2024The concentration of intracellular and extracellular potassium is tightly regulated due to the action of various ion transporters, channels, and pumps, which reside... (Review)
Review
The concentration of intracellular and extracellular potassium is tightly regulated due to the action of various ion transporters, channels, and pumps, which reside primarily in the kidney. Yet, potassium transporters and cotransporters play vital roles in all organs and cell types. Perhaps not surprisingly, defects in the biogenesis, function, and/or regulation of these proteins are linked to range of catastrophic human diseases, but to date, few drugs have been approved to treat these maladies. In this review, we discuss the structure, function, and activity of a group of potassium-chloride cotransporters, the KCCs, as well as the related sodium-potassium-chloride cotransporters, the NKCCs. Diseases associated with each of the four KCCs and two NKCCs are also discussed. Particular emphasis is placed on how these complex membrane proteins fold and mature in the endoplasmic reticulum, how non-native forms of the cotransporters are destroyed in the cell, and which cellular factors oversee their maturation and transport to the cell surface. When known, we also outline how the levels and activities of each cotransporter are regulated. Open questions in the field and avenues for future investigations are further outlined.
PubMed: 38946646
DOI: 10.1080/10409238.2024.2369986 -
Stroke Jul 2024GPR65 (G protein-coupled receptor 65) can sense extracellular acidic environment to regulate pathophysiological processes. Pretreatment with the GPR65 agonist BTB09089...
BACKGROUND
GPR65 (G protein-coupled receptor 65) can sense extracellular acidic environment to regulate pathophysiological processes. Pretreatment with the GPR65 agonist BTB09089 has been proven to produce neuroprotection in acute ischemic stroke. However, whether delayed BTB09089 treatment and neuronal GPR65 activation promote neurorestoration remains unknown.
METHODS
Ischemic stroke was induced in wild-type (WT) or GPR65 knockout (GPR65) mice by photothrombotic ischemia. Male mice were injected intraperitoneally with BTB09089 every other day at days 3, 7, or 14 poststroke. AAV-Syn-GPR65 (adenoassociated virus-synapsin-GPR65) was utilized to overexpress GPR65 in the peri-infarct cortical neurons of GPR65 and WT mice. Motor function was monitored by grid-walk and cylinder tests. The neurorestorative effects of BTB09089 were observed by immunohistochemistry, Golgi-Cox staining, and Western blotting.
RESULTS
BTB09089 significantly promoted motor outcomes in WT but not in GPR65 mice, even when BTB09089 was delayed for 3 to 7 days. BTB09089 inhibited the activation of microglia and glial scar progression in WT but not in GPR65 mice. Meanwhile, BTB09089 reduced the decrease in neuronal density in WT mice, but this benefit was abolished in GPR65 mice and reemerged by overexpressing GPR65 in peri-infarct cortical neurons. Furthermore, BTB09089 increased the GAP43 (growth-associated protein-43) and synaptophysin puncta density, dendritic spine density, dendritic branch length, and dendritic complexity by overexpressing GPR65 in the peri-infarct cortical neurons of GPR65 mice, which was accompanied by increased levels of p-CREB (phosphorylated cAMP-responsive element-binding protein). In addition, the therapeutic window of BTB09089 was extended to day 14 by overexpressing GPR65 in the peri-infarct cortical neurons of WT mice.
CONCLUSIONS
Our findings indicated that delayed BTB09089 treatment improved neurological functional recovery and brain tissue repair poststroke through activating neuronal GRP65. GPR65 overexpression may be a potential strategy to expand the therapeutic time window of GPR65 agonists for neurorehabilitation after ischemic stroke.
PubMed: 38946544
DOI: 10.1161/STROKEAHA.124.046954 -
Journal of Neurochemistry Jul 2024Alzheimer's disease (AD) is characterized by the accumulation of abnormally folded amyloid β-protein (Aβ) in the brain parenchyma and phosphorylated tau in neurons....
Alzheimer's disease (AD) is characterized by the accumulation of abnormally folded amyloid β-protein (Aβ) in the brain parenchyma and phosphorylated tau in neurons. Presenilin (PS, PSEN) 1 and PS2 are essential components of γ-secretase, which is responsible for the cleavage of amyloid precursor protein (APP) to generate Aβ. PSEN mutations are associated with tau aggregation in frontotemporal dementia, regardless of the presence or absence of Aβ pathology. However, the mechanism by which PS regulates tau aggregation is still unknown. Here, we found that tau phosphorylation and secretion were significantly increased in PS double-knock-out (PS1/2) fibroblasts compared with wild-type fibroblasts. Tau-positive vesicles in the cytoplasm were significantly increased in PS1/2 fibroblasts. Active GSK-3β was increased in PS1/2 fibroblasts, and inhibiting GSK3β activity in PS1/2 fibroblasts resulted in decreased tau phosphorylation and secretion. Transfection of WT human PS1 and PS2 reduced the secretion of phosphorylated tau and active GSK-3β in PS1/2 fibroblasts. However, PS1D257A without γ-secretase activity did not decrease the secretion of phosphorylated tau. Furthermore, nicastrin deficiency also increased tau phosphorylation and secretion. These results suggest that deficient PS complex maturation may increase tau phosphorylation and secretion. Thus, our studies discover a new pathway by which PS regulates tau phosphorylation/secretion and pathology independent of Aβ and suggest that PS serves as a potential therapeutic target for treating neurodegenerative diseases involving tau aggregation.
PubMed: 38946496
DOI: 10.1111/jnc.16155 -
Plant, Cell & Environment Jul 2024Plant pathogens cause devastating diseases, leading to serious losses to agriculture. Mechanistic understanding of pathogenesis of plant pathogens lays the foundation...
Plant pathogens cause devastating diseases, leading to serious losses to agriculture. Mechanistic understanding of pathogenesis of plant pathogens lays the foundation for the development of fungicides for disease control. Mitophagy, a specific form of autophagy, is important for fungal virulence. The role of cardiolipin, mitochondrial signature phospholipid, in mitophagy and pathogenesis is largely unknown in plant pathogenic fungi. The functions of enzymes involved in cardiolipin biosynthesis and relevant inhibitors were assessed using a set of assays, including genetic deletion, plant infection, lipidomics, chemical-protein interaction, chemical inhibition, and field trials. Our results showed that the cardiolipin biosynthesis-related gene MoGEP4 of the rice blast fungus Magnaporthe oryzae regulates growth, conidiation, cardiolipin biosynthesis, and virulence. Mechanistically, MoGep4 regulated mitophagy and Mps1-MAPK phosphorylation, which are required for virulence. Chemical alexidine dihydrochloride (AXD) inhibited the enzyme activity of MoGep4, cardiolipin biosynthesis and mitophagy. Importantly, AXD efficiently inhibited the growth of 10 plant pathogens and controlled rice blast and Fusarium head blight in the field. Our study demonstrated that MoGep4 regulates mitophagy, Mps1 phosphorylation and pathogenesis in M. oryzae. In addition, we found that the MoGep4 inhibitor, AXD, displays broad-spectrum antifungal activity and is a promising candidate for fungicide development.
PubMed: 38946254
DOI: 10.1111/pce.15021